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HomeMy WebLinkAboutSEPA EPIC-180-82 - VALLEY VIEW ESTATESALLENBAGH DEIS RESPONSES TO VALLEY VIEW ESTATES L.r' (:) .C3 U`. 0 0 Subject From 0 0 Date 513 19 41S c WOlsoWJon ®s GRAYLINE FORM 44 -900 2 -PART fi1983 • PRINTED IN U.S.A. R.W. Thorpe & Associates, Inc. Planning • Landscape • Environmental • Economics October 25, 1985 Rick Beeler City of Tukwila Planning Dept. City Hall 6200 Southcenter Blvd. Tukwila, WA 98188 ,. - - RE: Valley View FEIS Dear Rick: FC.CT2 _ . 1985 ray ti T 17., %A•II. A P1. ANMN G DEPT. Principals: Jon Potter Robert W. Thorpe, AICP Associates: Mary Cole Enclosed, please find the following graphics extracted from the Valley View DEIS. Figures Graphic Title 1 Location of Site 2 Aerial Photograph 3 Site Plan 4 Site Plan 5 Zoning Map 6 Slope Analysis 7 Landscape Plan 8 Noise Measurement Locations 9 Existing Land Use 10 Vicinity Street System 11 Existing Traffic Volumes 12 Projected Generated Traffic Volumes 13 1987 Daily Traffic Volume With and Without Proposed Project 14 Average Annual Accidents 15 Childrens Play Area Blow -Up 16 Site Utility Plan 17 Aerial Photograph 18 Cross Section 19 View from Tukwila Hill 20 Plan View 21 Sections of Site I have included all of the originals except for xerox copies of Figures 3, 7, 18, 19 and 21. The originals were sent to Puget Western upon request last January. Although the xerox copies are of a good quality we are searching for the originals and will transmit them when found. Please return the originals once you are through with them. We hope these are of use to you. If we can be of any further help please feel free to call. '-- ncerely n Potter, Principal Enclosure cc: Tom Russell Seattle: 1300 Alaska Bldg. • 2nd & Cherry • Seattle, WA 98104 • (206) 624 -6239 Anchorage: Suite 503 • 1110 West Sixth Avenue • Anchorage, AK 99503 • (907) 276 -6846 • TO RAY. Thom. & Associates, Inc. LETTER OF TRANSMITTAL 816 8•attt• Tow•r 3rc-•*a Unrv•rany S•attlo, 'rrastlinpton 88101 (204) 1324 -8239 8urt• 603.1110 W•st sixth Av•nu• Anchorap., AK 00603 (DOT) 27e -004e c r eL III 1:1.5 RteL Cileir- C_t , cDI - rr.kr.� I��- - �,►�r,� Cdy s • !e 001. WE AXE SENDING: Q Report ❑ Copy of letter Dace 1 Joo tio. 2-/Cla c--- Attention ire: veley titPil S _ ❑ Attached ❑ Under separate cover via ❑ Prints ❑ Plans ❑ Maps the following items Copies I Dace I No. Description 1 C , eD- Trrc.,scr, pile, I / z,/c:kS demo -, yS 1 ( TaESE ARE TRANSHI::ED as checked below: ❑ For approval ❑ Approved as •ubmitted 0 Resubmit copies for approval ❑ For your use 0 Approved as noted ❑ Submit copies for distribution o As requested ❑ Returned for corrections a Return corrected prints ❑ For review and comment ❑ 0 For Froposal RD4.ASR S due 19 G PRINTS RETURNED Ali :a LCA.N TO CS a COPT TO SIGNED SPE:: \': Go. ernu' • i • STATE OF V ■ 3HINGTON DEPARTMENT OF ECOLOGY Mail Stop PV -11 • Olympia. It astiington 98504 • (206) 459 -6000 January 15, 1985 Mr. Brad Collins City of Tukwila Planning Department. 6200 Southcenter Boulevard Tukwila, WA 98188 Dear Mr. Collins: DO CrrY i 4• ! •.re- r Thank you for the opportunity to comment on the draft environmental impact statement for the Valley View Estates. We reviewed the EIS and have the following comment. The Renton Sewage Treatment Plant (STP) is currently operating above desig capacity much of the time and it will be 'several years before it is ex- panded. There is no guarantee that sewer service will be available at the time desired for this development. If the treatment plant continues to operate well and meets the required effluent limits until the expanded facilities are operating, no restrictions will be placed on sewer connecti or extensions. If you have any questions, please call the Northwest Regional Office at (206) 885 -1900. BJR :pk Sincerely, Barbara J. itchie Environmental Review Section REPLY TO ATTENTION OF Planning Branch DEPARTMENT OF THE ARMY SEATTLE DISTRICT. CORPS OF ENGINEERS P.O. BOX C -3755 SEATTLE. WASHINGTON 98124 Bradley Collins, Director City of Tukwila Planning Department City Hall 6200 Southcenter Boulevard Tukwila, Washington 98188 Dear Mr. Collins: t1_50 5[1�`��..� HAI 2 8 1985 .. Ci°'t Y Ur' .i tl&dt'iL A PLANNING DEPT. We have reviewed the draft environmental impact statement (EIS) for Valley View Estates, Tukwila, Washington. With respect to the U.S. Army Corps of Engineers areas of responsibility for flood control, navigation, and regulatory functions, we do not have any comments. We do have some concerns regarding the proposed project and offer the following general comments. a. The geotechnical report appended to the draft EIS concludes that ". . . development of the property as planned is feasible . . . ." We have no disagreement with this statment, and we are in general agreement with all of the technical recom- mendations given. However, we believe that there is a question of whether or not development of homesites on this landslide - prone site is advisable. In our experience, control of landslides is an inexact and difficult task, and it often takes many years before a slide will completely react to changes such as vegetation removal, regrading, and installation or deterioration of drainage facilities. We are concerned that, if instability occurs at some future time, the developers will be gone, and the individual homeowners will find themselves in an unforseen, and possibly very expensive controversy. b. As stated in the report, the long -term stability of the site is dependent upon existing deep- drainage facilities which were installed by, and are apparently maintained by, the State of Washington. There appears to be no clear -cut agreement with the State regarding responsibility for this drainage system. This could result in serious disagreements later on. If sliding even- tually occurs again, or is eminent due to rising piezometric levels, how will responsibility be determined? Is it due to deterioration of the State's drainage system, or due to increased infiltration from vegetation loss and regrading of the site? Who -2- is responsible for remedial measures and /or drainage? This seems to us to be a very serious question which should be answered by formal agreement between the developer and the State of Washington. c. In our opinion there should be a clearly stated commit- ment by the developer that piezometric levels and slope movements will be monitored and evaluated throughout the entire life of the proposed project by a qualified geotechnical engineer who is familiar with the project. Thank you for the opportunity to review this statement. If you have any questions regarding our comments, please contact Mr. Steven F. Dice of my staff at the above address or by telephone (206) 764 -3624. Sincerely, !l�aa Et te a §44 44 SC' EVIS O[� //zet/85 .0)e wirn bleadir CITY OF TUKWILA CENTRAL PERMIT SYSTEM ENVIRONMENTAL REVIEW ROUTING FORM TO; PROJECT LOCATION 53 ,10 .,.e DATE TRANSMITTED I7EX., 2$ i41$44" STAFF COORDINATOR Flog: 1' THE ATTACHED ENVIRONMENTAL CHECKLIST WAS RECEIVED REGARDING THIS PROJECT. PLEASE REVIEW AND COMMENT BELOW TO ADVISE THE RESPONSIBLE OFFICIAL REGARDING THE THRESHOLD DETERMINATION. THE ENVIRONMENTAL REVIEW FILE IS AVAILABLE IN THE PLANNING DEPART- MENT THROUGH THE ABOVE STAFF COORDINATOR. COMMENTS REGARDING THE PROJECT YOU WISH CARRIED TO THE PLANNING COMMISSION, BOARD OF ADJUSTMENT, AND CITY COUNCIL SHOULD BE MADE ON THE ATTACHED CENTRAL PERMIT SYSTEM ROUTING FORM. BLDG n PLNG P.W. FIRE CN EPIC2 83 FILE POLICE P & R FILE NO. RESPONSE REQUESTED BY JPi , J5, I BT RESPONSE RECEIVED ITEM COMMENT ) 6 e, tJ .a�•.� �=�' fix ,. L` %�2 414.4v ?let"-47 AgZA 4_12La DATE /- '7� -�� COMMENTS PREPARED BY C.P.S. Form 11 City of Tukwila 6200 Southcenter Boulevard Tukwila Washington 98188 MEMORANDUM TO: Rick Beeler, Associate Planner FROM: Don Williams, Parks & Recreation Director DATE: February 13., 1985 SUBJECT: Dept. concerns regarding Valley View Estates E.I.S. and eventual dev. Concerning the Valley View Estates project I believe there are several items in the E.I.S. that should be addressed before any approvals or permits should be issued. As the coordinating department I assume you will be sure appropriate Building and Public Works staff will address my concerns, as well as your own. My convents should be conside- red•not as a response to the E.I.S. but to the conditions that must be met prior to the issuance of any permits. My concerns are as follows: A. p. 19 -The 6,175 sq, ft. play area meets only a 4 of the required recreation space. B. p. 44 & 125 - Sidewalk or trail construction is mentioned in several city documents. Because of these plans and the Sidewalk Ordinance it is an absolute necessity the developer construct a sidewalk all along Slade Way and 53rd Ave. So. In order to have safe access to Crestview Park and Trail #9.a properly constructed sidewalk should be required. A future trail is planned from Slade Way to the sidewalk under I -5 to the east of this devel- pment using W.S.D.O.T. land. This trail connection should also be considered. C. p. 121 -125 - Much of the developer's recreation space is to be the areas between and around the housing units. According to the E.I.S. the slopes in these areas will vary from 0 to 40 %. The only identified recreation facility is the children's play area at 6,175 sq. ft. and it assumed this area will be satisfactory concerning the degree of slope, although a detailed review should be done. The other recreation areas, approximately 15,000 sq. ft. will be in areas around the buildings - in the sloped areas. According' to Section 1. d. of Tukwila's Zoning Code no more than 50% of the uncovered recreation space may be located on slopes greater than 4 horizontal to 1 vertical (4 to 1 slope). In addition, under Section 1. e., the front, rear, and side yard setback required by the applicable zoning district shall not qualify as recreation space. Taking these two sections into consideration and not seeing other designated recreation areas I question if the developer meets the required on site recreation space. Please keep me informed as to how my concerns will be addressed. QTY OF TUKWILA CENTRAL PERMIT SYSTEM ENVIRONMENTAL REVIEW ROUTING FORM TO; (l BLDG n PLNG P.W. FIRE CN FILE POLICE n P & R P ROJECT\] a 41 45ISTPillEES 142t l 4, LOCATION 53 g) 4. suite wINNI FILE NO. DATE TRANSMITTED pet. 219,14841- RESPONSE REQUESTED BYXML145114,Bir STAFF COORDINATOR gi(I, �. RESPONSE RECEIVED THE ATTACHED ENVIRONMENTAL CHECKLIST WAS RECEIVED REGARDING THIS PROJECT. PLEASE REVIEW AND COMMENT BELOW TO ADVISE THE RESPONSIBLE OFFICIAL REGARDING THE THRESHOLD DETERMINATION. THE ENVIRONMENTAL REVIEW FILE IS AVAILABLE IN THE PLANNING DEPART- MENT THROUGH THE ABOVE STAFF COORDINATOR. COMMENTS REGARDING THE PROJECT YOU WISH CARRIED TO THE PLANNING COMMISSION, BOARD OF ADJUSTMENT, AND CITY COUNCIL SHOULD BE MADE ON THE ATTACHED CENTRAL PERMIT SYSTEM ROUTING FORM. ITEM COMMENT /t\1 a/4-71-- CD V-61(0) 93 \-1 111'4 1111/S rn�mdt Nnl h- . S7jLL -Avi rn ci. C.c�NC.�NS , / _ G3CA.jW L 14911 Trz c-o cu EA. -TIM LINJ77/?-45. PoaotroNsT Lk)t11,1 \to u r aVin .TT 1y T7DyNI TI//L5."" • car - 41 KA A V 4 U i cam Ur LN1 SCE V AL vu-k- czAps vi9-m -e5 F moG2L Tz LE-TrdtS r ) 1Q J \ C1C ' .«tCt L. ?k-c-'"‘• DATE I /Q(18S-- COMMENTS PREPARED BY C.P.S. Form 11 CITY OF TUKWILA CENTRAL PERMIT SYSTEM ENVIRONMENTAL REVIEW ROUTING FORM TO; 1.--1 BLDG PROJECT LOCATION53 SUIttee N6 DATE TRANSMITTEDpr , 2 Vi a+ STAFF COORDINATOR !I _ A, F--1 PLNG n P.W. FILE �PCJ.5 M. FILE NO. RESPONSE REQUESTED BY L , rigs' • RESPONSE RECEIVED THE ATTACHED ENVIRONMENTAL CHECKLIST WAS RECEIVED REGARDING THIS PROJECT. PLEASE REVIEW AND COMMENT BELOW TO ADVISE THE RESPONSIBLE OFFICIAL REGARDING THE THRESHOLD DETERMINATION. THE ENVIRONMENTAL REVIEW FILE IS AVAILABLE IN THE PLANNING DEPART- MENT THROUGH THE ABOVE STAFF COORDINATOR. COMMENTS REGARDING THE PROJECT YOU WISH CARRIED TO THE PLANNING COMMISSION, BOARD OF ADJUSTMENT, AND CITY COUNCIL SHOULD BE MADE ON THE ATTACHED CENTRAL PERMIT SYSTEM ROUTING FORM. ITEM COMMENT The information contained in this most recent DEIS has answered many of the concerns 1 voiced with "the contents of the previous document.. Still unanswered is my deep seated concern for the safety of human life and the preservation of property when the report itself Points up the fact that some lending institutions may not accept the buildings'a's collateral and insuring agencies may require a "rate higher than average. The immediate impact upon police services wili'be most visible in the increased calls for service and a longer response time in responding to these calls. This impact will be minimal. I am most appreciative of the Developers agreement to work in. close harmony. 'with the Crime Prevention Practioneer. Security costs at the building stage are approximately 50% lower than in the completed structure. Crime Prevention through better environmental design is a proven fact. DATE COMMENTS PREPARED BY fi1'! k » C.P.S. Form 11 Pv-Pco • • Subject x Pal LV�4 � J Speed Message From VCAC- • • Date JM Z8 19 17i lT c A1(40 (IUIeii i u Psre \ t fl<C_ SS il)O S %Ag COMM t5Ni W • 3, awl OA IMC - --S . PEL-2 L mac' IS I \t, IIVG Signed WilsonJones GRAYLINE FORM44 -900 2 -PART C1983 • PRINTED IN U.S.A. OFFICE MEMO CITY or TUKWILA TO: EPIC - 205 -83 FRO^": Bradley J. Collins DATE: January 24, 1985 SUBJECT: Extension of January 27, 1985, comment period on the Draft EIS. Today the U.S. Army Corps of Engineers requested a one day extension to the comment period in order for written comments to be delivered to the City. Based upon the fact that they received the DEIS on January 7, 1985, and have substantive comments on the slope stability and geology of the subject property, I hereby exercise the discretion under WAC 197.11.455 permitted to the Responsible Official to grant a one day extension to the comment period. Comments on the DEIS are now due by close of business on January 28, 1985. ns TO: FROM: DATE: SUBJECT: OFFICE MEMO CITY or TUKWILA. EPIC - 205 -83 Bradley J. Collins January 24, 1985 Extension of January 27, 1985, comment period on the Draft EIS. Today the U.S. Army Corps of Engineers requested a one day extension to the comment period in order for written comments to be delivered to the City. Based upon the fact that they received the DEIS on January 7, 1985, and have substantive comments on the slope stability and geology of the subject property, I hereby exercise the discretion under WAC 197.11.455 permitted to the Responsible Official to grant a one day extension to the comment period. Comments on the DEIS are now due by close of business on January 28, 1985. ns ........ ............................... ............... .............................. • ................ .............. .................... ............................... •190 City of Tukwila 6200 Southcenter Boulevard Tukwila Washington 98188 • . Gary L VanDusen, Mayor TO: FROM: DATE: SUBJECT: MEMORANDUM City Attorney Planning Department January 24, 1985 Valley View Estates DEIS During the January 22, 1985 public hearing on the draft environmental impact statement two issues were raised which require your review relative to the State Environmental Policy Act. Your opinion will be incorporated into the final EIS. 1. If someone wishes:to appeal the adequacy of the FEIS, when must this be done following issuance of the document? Section 25.2, Ordinance 1331, connects such an appeal to the "...decision appealed from." WAC 197.11.680(3)(v) requires consolidating an appeal with any appeal of a City decision, "...if both appeals are allowed in agency procedures." This concept appears reinforced by RCW 43.21C.075.3.(b). Since Board of Architecture Review will occur on this project (which has a ten day appeal period) and a building permit is required (no appeal period), it appears that an adequacy challenge of the FEIS must be made within 10 days of the BAR decision. Issuance of the FEIS is predicted to be 1 - 2 weeks prior to the BAR meeting. 2. Uphill property owners fear development /construction activity on the property will cause sluffage or sliding of parts of their properties. If this occurs, who is liable and what legal rights do these people have? The DEIS public comment period expires on January 27, 1985, and we anticipate providing your opinion and a summary of the comments to the applicant on the above within two days thereafter. 3. w w 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 1C l Pl C -2O5'� 3, v V I . W 3DATE //iii/ /'5 ORGANIZATION ADDRESS PHONE 1-7154 F/ A,/ 14 75-0 sZ4- AVE So 7-41-C-/ 721- /s46_ ?//Et /6Z CD .C2 4 ArE 50 -z4F- /72 4- .sue .4 1%e veil__ - ` ,.., rt-4,eni,cz l oa _ 760 5 a - --/ Gl ,?'-ii 3 -751 Et,, -f l 'llok S7 17o & .s-3 e S- 04/- re-si" i pD ,, rr ►4.,,c- WI`tc 16Hk3tri , /760.0 .--E-° 4a S .(0-5.--sits--- Fes l�Qlow 5,201 s [C--L\ 3( 2/77 j,./40" Gaiti1.- J.04._, sg.7/.. se) /0 a.--7e/o QC( 1 6 N N lbw AP2mbi a. /(,2_51 S L S° ,�,� ►s h ,Rot tlA vy\ • 1003% 0k‘% eve, So. all Z -03`73 QNanw Q. CLQ, t 62t'1''3 S 2'"d. 00.K.. so 241 6 - 2 8 4' Vd44 Po ./C -Y r1% Ave, A. z�'6- z l'92 p,, r,i Gam „//3 So /63_,,,,,.. 0/ 02vr /.340-' 12. 13. 14. 15. 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OS ."Cie.1/f-r-ter■teti - - 43 - ■•■ CITY OF TUKWILA CENTRAL PERMIT SYSTEM JAN 9 1985 BY TUKWILA FIRE PREVENTION BUREAU ENVIRONMENTAL REVIEW ROUTING FORM • TO; n BLDG (n PLNG n P.W. PROJECT - LOCATION5ag) SL,Pbe, DATE TRANSMITTED pe . , Z8, Iag4 STAFF COORDINATOR 14 CN E P I C2006 FILE 1::12OUL N4, POLICE n P & R FILE NO. RESPONSE REQUESTED BYMMLS.4111141115b RESPONSE RECEIVED THE ATTACHED ENVIRONMENTAL CHECKLIST WAS RECEIVED REGARDING THIS PROJECT. PLEASE REVIEW AND COMMENT BELOW TO ADVISE THE RESPONSIBLE OFFICIAL REGARDING THE THRESHOLD DETERMINATION. THE ENVIRONMENTAL REVIEW FILE IS AVAILABLE IN THE PLANNING DEPART- MENT THROUGH THE ABOVE STAFF COORDINATOR. COMMENTS REGARDING THE PROJECT YOU WISH CARRIED TO THE PLANNING COMMISSION, BOARD OF ADJUSTMENT, AND CITY COUNCIL SHOULD BE MADE ON THE ATTACHED CENTRAL PERMIT SYSTEM ROUTING FORM. ITEM COMMENT _ee-pvme4-7/5 M,///-2ei 74 1049s-74 /-ii/e4z- C 4-11--4-eA DATE ///4--/g5-- f 05-- COMMENDS PREPARED BY C.P.S. Form 11 CITY OF TUKWILA CENTRAL PERMIT SYSTEM FaGi6W0r fizETUNtAllN ets 4l ENVIRONMENTAL REVIEW RO R TO: ri BLDG ` PL P.W. FIRE PROJECT LOCATION 55142 400. 6 /604- 53 /tic Se.FILE,NO. DATE TRANSMITTED le11901114 STAFF COORDINATOR CN720 "QC15 EPIC 205 "TS FILE 1=1.axk M. (POLICE nP &R • RESPONSE REQUESTED BY RESPONSE RECEIVED THE ATTACHED ENVIRONMENTAL CHECKLIST WAS RECEIVED REGARDING THIS PROJECT. PLEASE REVIEW AND .COMMENT BELOW TO ADVISE THE RESPONSIBLE OFFICIAL REGARDING THE. THRESHOLD DETERMINATION. THE ENVIRONMENTAL REVIEW FILE IS AVAILABLE IN THE PLANNING DEPART- MENT THROUGH. THE ABOVE STAFF COORDINATOR. COMMENTS REGARDING THE PROJECT, YOU WISH CARRIED TO THE PLANNING COMMISSION, BOARD OF ADJUSTMENT, AND CITY COUNCIL SHOULD BE E 0 TEE ,TTACH D CE P�F IT SY M ROUjI�G��'`+�ie� • MME NT Q•'; �� ITEM fr-Thr-et ine4isfr ti rid h la na 54-111;1 /11-mA- ° 42-i l f 1 I -� �f04J r---eG`Lt (v--€ M- Q-VV+S Su %50 Q tive-s'11-- S CA. ,vi (1-1-1:1-.1 0-4 'J/74 rtPh cc-4-1 0 `. f -2 lri.-4 si y --ta t2, ld,,�r9 Qxyesctre) Co,..t btis k 6,l,' f -o,A0. -4 _/Z2pd- ►t.,er►T a CCeSS ,.b�� I / /li 9y/e C74ee4. 77 a 67;/-7 VV C � .(U�bbs nevi- ) dict -J 7 —pec,-84 (- k -o.e -1 Ire ();.0. ) kJ-'W S /2- -- ?c- .T (-! I OQa--f' -e 9 — /S — 8:3 DATE /0/4/C. COMMENTS PREPARED BY dahl C.P.S. Form 11 meimmonvasiftigiir OF T UKWI LA .:EN7nAl PERMIT � �iT �; � � E tau ti . By (MI. 2 - 1284 • ENV I RONME NT AL. f/41Tat... _.._....'...._ ]'b'6irl3l�O1REA'U T0: (i BLDG . n PLNG n .P. W. PROJECT LOCATION 3tZb Ji, S DATE TRANSMITTED -7124184' STAFF COORDINATOR' 1(!V: 5, RESPONSE RECEIVED THE ATTACHED ENVIRONMENTAL CHECKLIST WAS RECEIVED REGARDING THIS PROJECT. PLEASE REVIEW AND COMMENT BELOW TO ADVISE THE RESPONSIBLE OFFICIAL REGARDING-THE THRESHOLD DETERMINATION. THE ENVIRONMENTAL REVIEW FILE IS AVAILABLE IN .THE PLANNING DEPART-- MENT THROUGH THE ABOVE STAFF COORDINATOR.. COMMENTS REGARDING THE PROJECT YOU--WISH CARRIED TO THE PLANNING COMMISSION, BOARD OF ADJUSTMENT, AND CITY COUNCIL SHOULD BE MADE ON THE ATTACHED CENTRAL PERMIT SYSTEM ROUTING FORM. ITEM COMMENT • /74/641 1 • ur ed p/CD, • / i`naim 7 8/-4h. is ,s% .. �rivQ/ - /--k AGC455 te-Q 0141.e:4-4nel i° 51140M �S � /it PRu lyd l// /10`1- • Sid tS W� • laosn S_ Cn' 6 -s —Oct 3 .EP]c_ZOS— g3 FILE FIRE (i POLICE n P & R 5 IN FILE NO. RESPONSE REQUESTED BY '-i [ 31 184- DATE 7 -26 -ef¢ COMMENTS PREPARED BY OF TUKWI LA • • PERMIT NUMBER CONTROL NUMBER F 613 CENTRAL PERMIT SYSTEM - PLAN CHECK ROUTING FORM .� TO: 111 BLDG. PLNG, ill P1148 . FIRE POLICE . P, & R. PROJECT Vd., V_A ,-- ADDRESS. 53 %1,c4f,� DATE TRANSMITTED ftL0 / l7'- RESPO SE REQUESTED BY /-c -2 -C 1C. P. S, STAFF COORDINA _ � RESPONSE RECEIVED PLEASE REVIEW THE ATTACHED. PROJECT PLANS AND RESPOND WITH APPROPRIATE COMMENTS IN THE SPACE BELOW, INDICATE CRUCIAL CONCERNS. BY CHECKING THE. BOX NEXT TO THE LINE(S) ON WHICH THAT CONCERN IS NOTED: • . 1) P''ovolt Q1� L L� p-Or Gil 2) Pr", a e- 5 -4Ofrt. I /le tec4n -5 3) l i'e _��„ k. re g�lr e., e fs 9-0 sveyt 1/ 9 k/'l J/114) f3vr -e4 ` • E1 Pr;nr• C n 5 7'. �11 -e X i'1715h e-- j /1 eic4 1 v N� T P vgc Sec. (Z/c. j -e- e( c- t- r.”,it 41 z/I/ash • 6` .r� ye,/ - L 1 7 Y/) C e.- 4-/,..i. el ri ✓; I F fi�.)h5 a-- e4 S 0 "Fir-4-.1-.41a -- Ng ,2 rlr, ir" p f— 11r r.11714# c c 6 p 20 1 lv c e_ V s o ,c1 lc. y- L r, V t n q 1 . -P004 +vrhia9 r q,fi. r e-.9' 1.-ire,/ / 710 pr I.-o ec 71. c ,1, y 1N ,Lhro,,ho ,/• 543 /— -� D.R.C. REVIEW REQUESTED E PLAN CHECK DATE .5---/2 COMMENTS PREPARED BY (2-4/. FOPJI Tukwila • 0epartment Gary VanDusen Mayor Mr. Jor, ,Potter R. W. Thorpe & Associates • 815 Seattle Tower Third $ University Seattle, Washington 98101 Ser- tember 15, 1983 Dear Mr. Potter: In reply to your.letter of August 30, 1983: 1. Total number of responses by the Tukwila Fire Dept. during 1982 was; 896 Medical Aid 694 Fire 8 Service 2. Adeouacy of fire -flow in the area is not known. A flow -test will need to be conducted. 3. Tukwila Fire Dept. employs 24 firefighters .and officers, 3 staff personnel and one secretary. 4. Emergency response time to this area is estimated at 3 to 4 minutes, average. 5. Fire rating of the City is - Class 4 6. Refer to the enclosed cop of the May 12, 1982 plans review sheet for further comments and concerns. Yours truly, The Tukwila Fire Prevention Bureau cc :TFD file City Attorney Planning Dept. Encl.: May 12 Plan Review City Of Tukwila Fire Department, 444 Andover Park F..,, T. A....A_ _ _401t_ IS a5 151-6 V-NA - +- 2( 5. _U-V2cr_f e3F-016-1-1)12x 4L) (cO\L.s r-rL NQknicr.The c.0.191"Tl(WiS _ 'Cf3q24MCivr Prg MaSntS NjL r-t.„\1._ 00(NIOHILLT ,'IkLL \Acuc,s-e-na.)s7 st-4-vt_Ln mAgi3 10-rum_44.Ep..,__5 mtiu2iT _1(.1osmic t; Ile- 0 TETUE WslaE_ ROsT sToris Mit1(:).?„ 4-tiM Neigr -LCTQ31- RY-SUQO _utsRa elat-ELF ; bir ir-F-cooLess_csa9f_eri _Mar lea.) (F 1 elgr UP4.5)LA (M&) 1144-S 11-2-141-U-11_ 0 f t sr6NSIP ILo-7` C treir Off-• / k SU+ �4. 2PegrE (963sti3.- Water srtsvf f2-se(3 (LW7 1\14:gr7- 4*(0 716 ik.31(z-K, ON ., 113Q. vk Icr Z (._s Pfe4s- rv--€E--A--t \-cis ez-ceQOTY fa,(4-viAkS-Wv d? SlksTE. L11- u P ycss%-NA tthi- .1;6W ifr7 ryte( LcLet)c) 14( ctztb lir.s ht.10 Cr*, (v s6t4J 4d1 c..L Sl.l t7E • b (..lfilES 16\14b10 SUrS? Uk.)D� W 12UJmlB13CE:s 13. � 6wMkW4s L fili1.ON t?al2. dot T, efea. 13u1L1 14 . \Nbt\$r OM 1s51 CANS ? g�Ly1QCa SizopF. VALLEY VIEW ESTATES SLADE WAY & 53 AVE S EPIG180 -82 CITY OF TUKWILA OFFICE OF COMMUNITY DEVELOPMENT FINAL DECLARATION OF SIGNIFICANCE Description of proposal 108 - Unit Condominium Proponent H.M. Allenbach /Puget Western Location of Proposal Slade Way @ 53rd Ave. So. Lead Agency City of Tukwila File No. EPIC - 180 -82 This proposal has been determined to (have /R&ec) a significant adverse impact upon the environment. An EIS (is /beemak-) required under RCW 43.21C.030(2)(c). This decision was made after review by the lead agency of a completed environmental checklist and other information on file with the lead agency. Responsible Official Brad Collins Position /Title Date 5 -27 -82 Planning Director COMMENTS: Signature a • ,.�r►t ,. •_ C:t� y f Tukwila 6200 Southcenter Boulevard o Tukwila Washington 98188 1908 Frank Todd, Mayor MEMORANDUM TO: Larry Hard, City Attorney FROM: Brad Collins, Planning Director DATE: August 18, 1982 • SUBJECT: Al l enbach Building Permit Application Plan Review Reports Per your request, the attached materials are copies of the various Department review comments and a file list of deficiencies and code references. Will you be sending this information to Joel. Haggard or do you want this to go from the Planning Department? BC /blk 1908 Citf Tukwila 6200 Southcenter Boulevard Tukwila Washington 98188 Frank Todd, Mayor MEMORANDUM TO: Brad Collins, Planning Director FROM: Mark Caughey, Associate Planner DATE: 27 May 1982 SUBJECT: EPIC- 180 -82: Valley View Estates This memorandum is a follow -up to the Declaration of Environmental Significance issued this date for the Valley View Project. As provided in Section 11 of Tukwila Ordinance 1211, the responsible official may, at the time a Declaration of Significance is issued, direct that additional elements of review be included in the E.I.S. document. In reference to the concerns identifed in the Threshold Determination Document, we suggest that the following additional elements from the list in Section 11 be included in the Valley View Draft E.I.S. Elements (2) and (3): Economy /Tax Base - The content should be focused on a cost /revenue analysis of extending municipal services or upgrading existing services to this project site which is located at the urban fringe. Elements (5), (6) and (7): Quality of Life /Neighborhood Cohension/ Sociological Factors Currently, there are no multiple - family developments in the incor- porated area of McMi'cken Heights. The proposed project, if implemented, represents a significant departure from the prevailing low- density residential land use'pattern. The social implications and growth- inducing impacts of this project relative to the policies of the Comprehensive Plan should be analyzed. I suggest that we communicate the need to prepare these additional elements in the E.I.S. at such time as a pre -draft consultation is held with the project proponents. MC /blk i Threshold. Determination File WEPIC- 180 -82: Puget Western Condominiums (Valley View Estates) INTRODUCTION The proposed development, consisting of 108 condominium units on 5.3 acres, constitutes a major action within the language of RCW 43.21C.030(e) and as such is subject to compliance with the provisions of the State Environmental Policy Act. An environmental checklist form prepared by the project proponent was circulated to the various departments of the City administra- tion, and a number of comments were received. DISCUSSION . The following is a summary, by department, of comments received in response to the S.E.P.A. Checklist: A) Public Works 1) Checklist Section I, Item 11: Future impact of planning by Val -vue sewer District and Tukwila Six -Year Street Plan should be analyzed. 2) Section II, Item 1 (Earth): Historic slide conditions not given satisfactorally - complete discussion; preliminary soils report gives insufficient details on feasibility of construction bearing capacity and scope of grading. See Fraser letter of 5 -17 -82 attached. 3) Section II, Item 13 (Transportation): Disagree with statement that increase in,,project traffic will not affect the existing transporta- tion system._ The City's Six -year Street Plan recognizes Slade Way to- be substandard. Comprehensive traffic study needed per 5 -17 -82 letter. 4) Section II, Item 16 (Utilities): Water service and storm water management demands not quantified - comprehensive . study required per 5 -17- •2 letter. Recreation'Department: 1) Checklist Section II, Item 19: Disagree with negative response on recreational opportunity impacts. No useable recreational facilities provided on -site in relation to the anticipated expansion of neighbor- hood population. Adequacy of recreation space and diversity within the project context needs further investigation. 2) Potential recreational trail connections should be explored. C) Fire Department:. 1) Checklist.Section II, Item 14 (Public Services): Adequate water supply from District W75 facilities for fire suppression purposes is questionable; further study required. D) Police Department: 1) Checklist Section II, Item 13(.c & d): Adequacy of access /site distance relative to increase of project- related traffic on adjoining streets is not clear. 2) Checklist Section II, Item 14(b): Increased population and change in land use will increase demand for police services; impact investigation required. CONCLUSION It appears that there are a number of topic areas which have not been investi- gated to the level of adequacy expected under SEPA. In addition, the Washington State Supreme Court, in its decision in the Norway Hill v. King County Council case (87 WN 2d. 267) articulated a series of criteria under which a Declaration of Significance is obligatory: 1) Change of use type from existing use: In the present case, the site is to be transformed from a wooded, unpopulated area into a suburban multi- family neighborhood, similar to the Norway Hill circumstance. 2) Scale of the project: The number of units proposed in this project is substantial, both in absolute terms and relative to other residential developments in the neighborhood. 3) Degree of change in use: As there is .no multiple- family use in McMicken Heights at this time, the proposal represents a shift in the present use configuration of the general vicinity. For these reasons, a Declaration of Significance and requirement for an Environmental Impact Statement in accordance with WAC- 197 -10 -350 is recommended. MC /blk City of Tukwil' 6200 Sou h ;enter Boulevard Tukwila V►asgton 98188 ^' . PLANNING DEPARTMENT T R A N S M I :.T T A.L • `7'Y •:-iz �t i:r.�..� •i a. -4 -:Y, v' Srrki•'..'� � .��- ..he -I�a:~: _�..•�i•C -arty, cry - - u"e�•tj .± - ,t- r�s �<ft sa51 e t„LSLa.t.1:t ter!7- :E ° �G....0 ��ar;� • POLICE DEPT .'T DATE OF = TRANSMITTAL BUILDING' • FIRE • PUBLIC WORKS DEPT: L, r ECREATION,DEP PROJECT_rs jal✓� LOCATION C 2 J0.6 Lb�� Wa 'The :above .mentioned applicant has' submitted the ,following plans or materials .... for the above. r'eference project. ^T =ir=` - � 7 7._ - - - _..vi ronmental -Checklist == - LJ.Prel imi nary —Plat' Environmental Impact State Final P1 at ment Site /Development Plans �'_: 0 Rezone__ Request;, Shoreline Permit Application Variance Request D Conditional Use Permit QOther:`. ------ Application The attached materials are sent to you for your - review and comment. - -- The Planning Dept. needs your comments to satisfy review procedures and to complete ,the project . file. Please use the space provided below for your - comments or attach a separate sheet. Requested response date: 4 : / 17 '/ e5 Review Department comments: 4s.0-s.� 3 o /-p/ o -B --°- -- Citylgf Tukwila 6200 Southcenter Boulevard Tukwila Washington 98188 Frank Todd, Mayor M EMORANDUM TO: MARK CAUGHEY FROM: Don Williams 0,2371/ DATE: May 17., 1982 ' SUBJECT: E.C.F. RESPONSE REGARDING PUGET WESTERN CONDOS. The E.C.F. contained a small plat map and, of course, the developer's responses to the various questions asked. This response is based on the limited information before me at this time. Question #19 asks if the project will have an impact upon the quality or quantity of existing recreational opportunities. The answer indicated is "no." I cannot agree and would add the developer must assume the 110 to 200 residents will seek recreation opportunities from within this community. The need for parks and recreation programs will certainly be by the new residents. With this need in mind, I have reviewed the developer's plans and see no "usable" recreation facilities such as picnic areas, tennis courts, play courts, swimming pool or recreation building. I request the developer be encouraged to develop "usable" recreation facilities for the condo residents. Currently this part of the City has no developed park, but is served by the Tukwila Community Center's programs. If some nearby park land isdevel- oped, .i t would satisfy most .of the resident's needs, .however., there a strong potential that other such projects in this general area, when developed, will also place demands on the potential park. I will request that any such development in the McMicken community provide such "usable" space. The potential Leavy use of the new park exists now with both the single family residential area and nearby commercial area presently seeking the development of the park. Residents who will live in developments such as Puget Western's will certainly add to the park's usage. I did recognize the 1.7 acres of green belt which will help separate and screen noise, light, glare, etc., however, it is not "usable" space from my point of view. MARK CAUGHEY May 17, 1982 Page 2 E.C.F. RESPONSE REGARDING PUGET WESTERN CONDOS. Also, on the north end of the project, we have Trail #9 on Seattle's large pipe - Tine R/W. A possible trail connection exists from the development to the trail, however, approval would be needed from the Seattle Water Department. On the south end of the project, we would like to talk to the developer with regard to an easement for the development of a foot trail from Slade Way to Klickitat Drive. Presently this potential trail is part of our new park plan. I would like to discuss this idea with the developer at the ap- propriate.time. DW /co L1 PLANNING DEPARTMENT TRANSMITTAL • 7901 DATE OF TRANSMITTAL. `i . / 1 TO:= ..::_:v_:: ❑ BUILDING .DEPT.:: FIRE DEPT.:: PUBLIC 'WORKS DEPT. OPOLICE DEPT. ❑ RECREATION DEPT. PROJECT: LOCATION:-- W0s 1,ON G27� The above mentioned applicant has submitted for the•above reference project: nvironmental Checklist ❑ Preliminary Plat ❑ Environmental Impact State- ❑ Final Plat ment. the following plans or Site /Development Plans". ❑ Rezone Request_: ❑ Shoreline Permit ApplicationD Variance Request ❑ Conditional Use Permit ❑ 0ther: Application The attached materials are sent to you for your review and comment. The Planning Dept. needs your comments to satisfy review procedures and to complete the project file. Please use the space provided below for your comments or attach a separate sheet. Requested response date: / (7 8Z Review Department comments: ( 'TAAL, Ct71'.�.ti/4,#.14/ 5/11/82 POLICE DEPARTMENT'S RESPONSE TO PUGET WESTERN CONDO ENVIRONMENTAL CHECKLIST. We disagree with the developer's response to Question #13, Sections (c) & (d). It appears to us that the addition of an additional 108 living units in a rather small area will have a major impact on the existing transportation sys- tem in the area. Slade Way, 53rd Ave. So., & So. 160th Streets will probably have to be upgraded to handle the increased traffic. Access to and from this project will have to be carefully planned to avoid traffic accident problems since the driveways appear to be located in a hilly, curvy area where sight distances could create a problem. If entrances /exits are not carefully planned, there will be a substantially increased risk of traffic accidents which will cause people to seek alternate routes. We would also like to see at least one more point of ingress /egress, preferably near the middle of the complex. We also disagree with the answer provided to Question #E14 (b): It is our opinion that the addition of 108 living units will definately have an im- pact on police protection. Traffic in the area will certainly increase causing an increased load on the traffic enforcement and accident investigation people. One hundred and eight additional living places in the City means an increased load on the department to provide routine patrol services as well as criminal investigations of incidents that will inevitably increase because of having buildings where none now exist. Residential property will increase the number of burglaries, auto thefts, domestic incidents and other crimes to which the department must respond and investigate. The problem is not in- surmountable but it will most assuredly have a negative affect on police pro- ' tection City wide unless police manpower allocations are increased. We would also like to request that the-architect make contact with the Tukwila Police Crime Prevention Officer prior to final approval of landscaping and lighting plans so that we can make specific suggestions from a Crime Preven- tion viewpoint. City of Tukwi 6200 Sou:hcenter Boulevard Tukwila Y►7s.+u^ on .98188 PLANNING DEPARTMENT TRANSMITTAL DATE :OF_:TRANSMITTAL . / / $2 TO:- - -- PROJECT: LOCATION: The be for the -above reference project: nvi ronmen.tal Checklist ❑Preliminary _Plat ❑ Environmental Impact State -. ❑Final Plat ment Q Site /Development Plans ❑ Rezone Request.. ❑ Shoreline Permit Application0 Variance Request Conditional Use Permit DOther: App)ication The attached materials are sent to you for your review and comment. The Planning Dept. needs your comments to satisfy review procedures and to complete the project file. Please use the space provided below for your comments or attach a separate sheet. BUILDING DEPT::-: FIRE: DEPT.`_`: >: PUBLIC WORKS _DEPT. U POLICE DEPT: ❑ RECREATION .DEP.T. fkier Requested response date: 4 / I/ Review Department comments: P/ J 2 csS r0a /s v ,b_o1�" �� ..�X ctc � 1 S �o hi9Ji, � q7 ° ��h)z� ,„�r'tJ' Ivor"- $ ' '/Y i • -F- w. p. r 5 i 4 71'4 �, / / 5 h o c PLANNING DEPARTMENT TRANSMITTAL POLICE . DEPT. - - -= f6*-A.11f:=!STrAc*31:7 A : • The above mentioned applicant has'submitted the following plans or materials.. _ for`the •above: reference project: Environmental Checklist ❑Preliminary Plat Environmental Impact State-. ❑ Final Plat ment ❑ Site /Development Plans ❑Rezone Request ['Shoreline Permit Application❑ Variance Request ❑Conditional Use Permit ❑Other: Application The attached materials are sent to you for your review and comment. The Planning Dept. needs your comments to satisfy review procedures and to complete.the project file. Please use the space provided below for your comments or attach a separate sheet. Requested response date: 4 / I1 ,'j 82/ Review Department comments: •_‘/ 7H /7 Z? 7909 City a Tukwila 6200 Southcenter Boulevard Tukwila Washington 98188 Frank Todd, Mayor MEMORANDUM To: Brad Collins, Planning Director FROM: Phillip. R. Fraser, Senior. Engineer DATE: 5/17/82 SUBJECT: Public Works Department Review. of Valley View Estates /53rd Avenue South and Slade Way The Public Works Department has provided a preliminary review to determine the completeness of the subject site development per plan submittal A -1, C -1, C -2 and C-3 and the report GeoTechnical Design Consultation Proposed Condominium Development, Slade Way and 53rd Avenue South from Mithune Associates - submitted 5/3/82. Per this review a resubmittal of the report and plan documents is required of the developer to address the following deficiencies: 1. Report GeoTechnical Design Consultation Proposed Condominium Develop - ment, Slade Way and 53rd Avenue South a. The submitted Geotechnical Design Consultation Report is considered preliminary in nature and not a final soils report document. This particular site is adjacent to and /or the site itself has been in- volved in large earth slides in both the recent and distant past. b. Because substantial drainage problems have existed with the site which may limit the type of developments which can be proposed, it is con- sidered appropriate (as stated in "further studies" portion of the report), that several borings and sub - surface investigations be carried out in a final soils report. A hydraulogical study and field investi- gation are considered necessary prior to final conclusions as to the number, type, size and location of the sitings of the building struct- ures and required utilities on -site and in the adjacent public right - of -way. Included in the hydraulogical analysis shall be a survey of the exist- ing 12 -inch City storm system traversing the property through easements A determination shall be made as to the adequacy of the existing storm system to accomodate the proposed development. Valley View EstatAl(Continued) Page 2 of 4 2. Hydrant /Fire Loop /Sprinkler and Domestic Service a. Plan C -3, outline specification ;'3 - violation of the Tukwila Munici- ple Code 14.04.060. Per A.P.W.A. Specification Requirement 95% com- paction shall be substituted for 90% stated compaction. Excavation trench material may be.used as back -fill if it conforms to A.P.W.A.'s 73- 2.02A. b. Plan C -3 outline specification n6 - violation of Tukwila Municipal Code 14.04.060. Mechanical joints for water mains in Tukwila are not allowed. Non- restrained joints shall be rubber gasket, push -on type, (i.e., Tyton Joint). c. Plan C-3 outline specification n7 violation �tandardsaofuWateraDistric' Code 14.04.060. Number 7 states construction #75 should read construction standards of the City of Tukwila. d. Plan C -3 outline specification r9.- violation of Tukwila Municipal Code 14.24.030. Inadequate spacing and number of fire hydrants. e. Plan C -3, outline specification #10 - violation of Tukwila.Municipal Code 14.04.060. 1. The proposal is to connect to the main on the West Valley Highway is over one mile, as the crow flies, from the job site, is unreal- istic. 2. Proposed use of the Mueller H -610 tapping sleeve is for cast iron water mains in the 14 -inch to 48 -inch size only, therefore inappro- priate in terms of size for the water mains indicated on the pro - posed development. An H -610 also is a chaulked tapping sleeve which is not allowed. f. Plan C -3 outline specification violates Tukwila Municipal Code 14.04.06 This plan is deficient in number of gate valves required by the Public Works Department. g. Plan C -3 violates Tukwila Municipal Code 14.04.230 and Tukwila Municipa Code 14.04.250 (C) - location of the water meters and recorded easement or letter of intent to provide recorded easements shall be provided wit final plan submittal for'the purpose of allowing Public Works Departmer staff access to the water meters. h. Plan C -3 outline specifications violation f "Water systems and exten- sions Submittal Policy 05 -12, Item t1 which states, sions for both domestic, irrigation and fire service. Fire services shall be approved by insurance underwriters and the Tukwila Fire Depar. ment prior to submittal to the Public Works Department for review." Th development of Slade Way to current City standards will include mains and hydrants. Valley View Estill (Continued) Page 3 of 4 • 3. Sanitary Sewerate System a. Plan C -3 outline specification r2.- violation of City Ordinance W1250, per A.P.W.A. 1981 Edition, Division III, 61 -5, and Standard.Plan W62, all rigid pipe shall be Class "B" bedding and all flexible pipe shall be Type "F" bedding. Tukwila design requirements, where questionable soils conditions and history of sliding have occurred, such as this site, the bedding requirements revert to those equal or better to "under paved areas ". b. The existing sewerage system for site development will connect into is the Val -Vue Sewer District. A letter from Val -Vue District offices . as to their requirements is required to complete the plan submittal. At some in the future this sewerage system may be turned over .to the City. Therefore, requirements of the Tukwila Municipal Code and the Public Works Department design requirements shall be met with the proposal. The Public Works.Department currently requires that no. structures be • placed over existing sewer lines or easements, (i.e., Buildings 3, 6, '7,.10.& 11). Those structures sited over existing Val -Vue sewer.mains shall be relocated and /or the existing mains relo.cated as part of the proposal. c. Plan C -2 outline specifications and plans fail to call out a minimum 2% grade per Tukwila Municipal Code 14.12.150 for Sanitary Side Sewers. d. Plan C -3, proposed prefabrication sewerage life station: this submittal is deficient in the following submittals, 1) complete plan set_ of sewer • age lift station drawings, .2) hydraulic calculations, 3) pump curves, 4) letter from D.O.E. indicating that requirements for construction in- cluding storage and stand -by requirements have been met. Per the City' of Tukwila's requirements the 4 -inch force main shall be ductile iron pipe, Class 52. 4. Curb Cuts /Access /Sidewalks - including public roadway 'improvements a. A traffic study to allow for this type of development outlining private and public improvements in Slade Way and 53rd, is required as part of a complete submittal. b. Plan C -1, C-2 and C -3, per Tukwila Municipal Code Chapter 11.64, OrdinE #1233, 1217 and 1158 - whenever building permit application is made for the construction of a multi- residential, commercial or industrial structures within the City, the party seeking such permits shall submii a sidewalk construction plan for approval by the departments of Public Works and Planning. In lieu of such a plan submittal per Tukwila Muni- cipal Code 11.64.040 exceptions or waivers to this requirement may be granted by the City Council. As final grade and configuration of Slack Way. is not known by Public Works, it is recommended that the developer agree to participate in a future L.I.D. to improve the roadway includ- ing sidewalks or improve the portion of the road fronting his property when the final grade and configuration is known. Valley View Estes (Continued) Page 4 of 4 411 5: Storm Drainage a. Accompanying-the plan documents shall be the hydraulic calculations and analysis including a survey of.the existing City.storm system relative to the feasibility for the site development. Included in this •hydraulic report shall be the needed .upgrading of.the storm :system within the property and also to.the public right -of -way in.Slade Way .and 53rd Avenue South. (The recent..cave -in of over. '..100.feet of Slade Way adjacent to the:property may require special considerations for.the siting of structures and, utilities.) Per past. practices, a violation of Tukwila design requirements - - al.l;:.storm.: pipe .provided at. over .20% grade (i .e. , :Building r2 - 46%; :grade',and:._Buildings.#8,_and r9 - 40% grade).shall be provided • with:;ductile iron pipe and 'anchors. r -_ - _ Plan `:C -1 outline specification r2 - .viol.ation of.Tukwila•design -specifications for. providing... underground: utilities. and unsuitable 'or. :prior slide areas compaction. shall. be 95% throughout. • er,A:P.W :A..- 1981 Edition, Division III 61 -5 and Standard Plan 62 'a11 rigid pipe shall be Class "B" bedding and'.all: flexible pipe shall be Type. "F" bedding. • xc: Byron G.- Sneva, Public Works Director Ted Freemire, Public Works Superintendent Dave Grage,, Water Department Crew Chief Ray Do11,-Sewer Department Crew Chief Ralph Trepanier, Street Department Crew Chief PF:jst " -• • -- • Reques t 1 • PUBCfC.7i46 2 , - • • • - - • . • • • , _Impact State- : Pr - el minay Plat Environmental ---- nvironmental Checklist ment_ Site/Development Plans [1] Rezone Request.- - - - Shoreline Permit ApplicationE Variance Request Conditional Use Permit DOther: Application The attached materials are sent to you for your review and comment. The Planning Dept. needs your comments to satisfy review procedures and to complete . the project file. - Please use the space provided below for your comments or attach a separate sheet. ed -esponse date: / 17 • / Review Department comments: (/ (:s2 (-) 0-tt_ ‹->(--e-Ar, rx-c,,y 7 1fira'— CITY OF TUKWILA i ENVIRONMENTAL CHECKLIST FORM 01-.3 1 3 1982 GUiL D!ItG. Gc'r T,T This questionnaire must be completed and submitted with the application for permit. This questionnaire must be completed by all persons applying for a permit from the City of Tukwila, unless it is determined by the Responsible, Official that the permit is exempt or unless the applicant and Responsible Ufficial previously agree an Environmental Impact Statement needs to be completed. A fee of $50.00 must accompany the filling of the Environmental Questionnaire to cover costs of the threshold determination. I. BACKGROUND 1. Name of Proponent: Mr. & Mrs. Herman M. Allenbach 2. Address and Phone Number of Proponent: c/o The Mithun.Associates, P.S. 2000. 112th Avenue NE, Bellevue, WA 98004 454 -3344 3. Date Checklist Submitted: May 3, 1982 4. Agency Requiring Checklist: City of Tukwila 5. .Name of Proposal, if applicable: Valley View Estates 6. Nature and Brief Description of the Proposal (includingi but not limited to its size, general desion elements, and other factors that willaive an accurate understanding of its scope and nature): A condominium complex, geared to young professionals, consisting of 18 buildings of 6 units each. Units will step across the hill. Each building will be a maximum footprint of 36' wide x 63' long. Minimum distance between buildings shall be 20'. Materials will be a combination of stucco and horizontal cedar siding. Roofs will be composition. 7 Location of Proposal (describe the physical setting of the proposal, as weli as .the extent of the land area affected by any environmental im- pacts, including any other information needed to give an accurate under- standing of the environmental setting of the proposal): The site is located west of the I -5 corridor bounded by Slade Way to the south. The area affected is approximately 2.5 acres of R -4 zone and 2.9 acres of RMH zone. The R -1 zone of approximately 1.7 . acres will remain intact as green belt. The site slopes from 8% to 36%. Althou•h soils are of sound material the water runor , •ot su•sur ace an sur ace, as cause • previous sli•es. green belt corridor varying from 45' wide to 225' wide will be maintained between the existing single famiiy housing to the west and this development. 8. Estimated Date for Completion of the Proposal:. End 1983 9. List•of all Permits, Licenses or Government Approvals Required for the Proposal (federal, state and local): (a) Rezone, conditional use, shoreline permit, etc. YES NO X (b) King County Hydraulics Permit YES X NO (c). Building permit YES x N0 • (d) Puget Sound Air Pollution Control Permit YES NO x (e) Sewer hook up permit YES x NO (f) Sign permit YES x NO (g) Water hook up permit YES x NO (h) Storm water system permit YES x NO (i) Curb cut permit YES x NO (j) Electrical permit (State of Washington) YES x NO (k) Plumbing permit (King County). YES x NO (1) Other: 10. Do you have any plans for future .additions, expansion, or futher activity related to or connected with this proposal? If yes, explain: No expansion to occur. 11. Do you know of any plans by others which may affect the property covered by your proposal? If yes, explain: No 12. Attach any other application form that has been completed regarding the pro- posal; if none has been completed, but is expected to be filed at some future date, describe the nature of such application form: Application for building permit, also see above. II. ENVIRONMENTAL IMPACTS (Explanations of all "yes" and "maybe" answers are required) YES MAYBE NO 1. Earth. Will the proposal result in: (a) Unstable earth conditions or in changes in geologic substructures? (b) Disruptions, displacements, compaction or overcover- ing of the soil? x (c) Change in topography or ground surface relief fea- tures? (d) The destruction, covering or modification of any unique geologic or physical features? _ x 1. EARTH Seven of the 18 proposed buildings are located in existing slopes in excess of 20% and reaching a maximum of 37 %. These are building numbers 1, 2, 5, 6, 7, 10 and 11. Of the seven buildings placed on these slopes, building numbers 2, 5, 6, 7 and 11 will have the grades adjacent to them adjusted. All grading work will be performed per soils engineers recommendation. All work to be performed during normal business hours. Site contouring will direct water away from the building and will be controlled to eliminate erosion. 3. WATER The addition of buildings to this site would create changes to the water absorption rate as well as changes to the drainage pattern. For this reason narrow (36' wide) buildings have been designed to minimize hydraulic problems. A storm detention system has been designed to catch all existing and new run -off before crossing the parking lot and driveway spline. 5. FAUNA Although smaller buildings have been designed and it is the intent of the proponent to phase construction with sales of units the completed project would reduce the number of land animals and birds. YES MAYBE NO ■ (e) Any increase in wind or water erosion of soils, either on or off the site? x (f) Changes in deposition or erosion of beach sands, or changes in siltation, deposition or erosion which may modify the channel of a river or stream or the bed of the ocean or any bay, inlet or lake? x Explanation: 2. Air. Will the proposal result in: (a) Air emissions or deterioration of ambient air quality? (b)' The creation of. objectionable odors? (c) Alteration of air movement, moisture or temperature, or any change in climate, either locally or regionally? Explanation: For approximately three working days, asphalt paving will occur. Otherwise no odors will be emitted by occupants. 3. Water. Will the proposal result in: (a) Changes in currents, or the course or direction of water movements, in either marine or fresh waters? (b) Changes in absorption rates, drainage patterns, Dr the rate and amount of surface water runoff? x _ (c) Alterations to the course or flow of flood waters? x (d) Change in the amount of surface water' in any water body? x (e) Discharge into surface waters, or in any alteration of surface water quality, including but not limited to temperature, dissolved oxygen or turbidity? (f) Alteration of the direction or rate of flow of ground waters? ' (g) Change in the quantity of ground waters, either through direct additions or withdrawals, or through interception of an aquifer by cuts or excavations? YES MAYBE NO (h) Deterioration in ground water quality, either through direct injection, or through the seepage of leachate, phosphates, detergents, waterborne virus or bacteria, or other substances into the ground waters? x (i) Reduction in the amount of water otherwise avail- able for public water supplies? x Explanation: See attached. 4. Flora. Will the proposal result in: (a) Change in the diversity of species, or numbers of any species of flora (including trees, shrubs, grass, crops, microflora and aquatic plants)? (b) Reduction of the numbers of any unique, rare or . endangered species of flora? (c) Introduction of new species of flora into an area, or in a barrier to the normal replenishment of existing species? (d) Reduction in acreage of any agricultural crop? x Explanation: The proponent will be adding landscaping to offset the selective removal of vegetation. 5. Fauna. ` Will the proposal result in: (a) Changes in the diversity of species, or numbers of any species of fauna (birds, land animals including reptiles, fish and shellfish, benthic organisms, insects or microfauna)? (b) Reduction of the numbers of any unique, rare or endangered species of fauna? (c) Introduction of new species of fauna into an area, or result .in a barrier to the migration or movement of fauna? x (d) Deterioration to existing fish or wildlife habitat? X Explanation: See attached YES 'MAYBE NO 6. Noise. Will the proposal increase existing noise levels? Explanation: . Automobiles will be brought on to the site Cmaximum 162 for this project). 7. Light and Glare. Will the proposal produce new light or glare? X Explanation: The parking lot will u,e non -glare lighting on 20' poles.. The low reflective glass have been set 45 to the street to maximize view and minimize reflectance. However, cars will be coming onto the site after dark, projecting light beams. 8. Land Use. Will the proposal result in the altera- tion of the present or planned land use of an area? Explanation:._ The planned use for this parcel of property is R -1 even though the parcel is adjacent to I -5 freeway and. i s buffered from existing R -1 via +40.' grade change and mature vegetation. 9. Natural Resources. Will the proposal result in: (a) Increase in the rate of use of any natural resources? x (b) Depletion of any nonrenewable natural resource? x Explanation: A. Electricity will be used for heating. B. Concrete, gypsum drywall, glass and roofing are non - replenishable materials. 10. Risk of Upset. Does the proposal involve a risk of an explosion or the release of hazardous substances (including, but not limited to, oil, pesticides, chemicals or radi- ation) in the event of an accident or upset conditions? Explanation: x 11. Population. Will the proposal alter the location, distribution, density, or growth rate of the human population of an area? YES MAYBE NO x Explanation: Although many of the units are one bedroom units geared for young professionals the growth rate will be affected. The addition of 108 units will alter the existing distribution of people as well as density. 12. Housing. Will the proposal affect existing housing, or create a demand for additional housing? Explanation: 13. Transportation /Circulation. Will the proposal result in: (a) Generation of additional vehicular movement? (b) Effects on existing parking facilities, or demand for new parking? _x (c) Impact upon existing transportation systems? x (d) Alterations to present patterns of circulation or movement of people and /or goods? x (e) (f) Alterations to waterborne, rail or air traffic? Increase in traffic hazards to motor vehicles, bicyclists or pedestrians? x •x Explanation: The site presently does not have any cars on it. The increase in auto movement will increase hazards. The increase in cars will not affect existing transportation systems. It is expected that at peak hours 1/2 to 2/3 of all vehicles . will be accessing onto public roads. 14. Public Services. Will theproposal have an effect upon, or result in a need for.new or altered governmental services in any of the following areas: (a) Fire protection? x (b) Police protection? x — (c) Schools? x (d) Parks or other recreational facilities? x (e) Maintenance of public facilities, including roads? (f) Other governmental services? YES MAYBE NO Explanation: Slade Road is planned for future improvements. Additional maintenance would be required. Buildings will be sprinklered for fire safety. A possible increase in police protection may be necessary. However each unit will be wired for alarm system. 15. Energy. Will•the proposal result in: (a) Use of substantial amounts of fuel or energy? (b) Demand upon existing sources of energy, or require the development of new sources of energy? Explanation: Puget Power indicates adequate power supply.. 16. Utilities. Will the proposal result in a need for new systems, or alterations to the following utilities: (a) Power or natural gas? _ (b) Communications systems? — (c) Water? x (d) Sewer or serstic tanks? (e) Storm water drainage? (f) Solid waste and disposal? Explanation: .Other than utility hook -ups, the only alterations will be the addition of a detention system. 1 17. Human Health. Will the proposal result in the crea- tion of any health hazard or potential health hazard (excluding mental health)? Explanation: x x x x x x • �i 18. Aesthetics. Will the proposal result in the obstruc- tion of any scenic vista or view open to the public, or will the proposal result in the creation of an aesthetically of- fensive site open to public view? YES MAYBE NO Explanation: A subjective question. However the adjacent properties are above roof heights of this project. Site will be screened from west by existing mature vegetation. 19. Recreation. Will the proposal result in an impact upon the quality or quantity of exist- ing recreational opportunities? Explanation: 20. Archeological /Histroical. Will the proposal result in an alteration of a signifi- cant archeological or his- torical site, structure, object or building? Explanation: CERTIFICATION BY APPLICANT: I, the undersigned, state that to the best of my knowledge the above information is true and complete. It is understood that the lead agency may withdraw any.declaration of non - significance that it might issue in reliance upon this checklist should there be any willful misrepresentation or willful lack of full disclosure on my part. Signature and Title // Date x x J11Lq 1906 City f Tukwila 6200 Southcenter Boulevard Tukwila Washington 98188 Frank Todd, Mayor July 13, 1982 Dr. and Mrs. Herman M. Allenbach C/0 Mithun Associates, P.S. 2000 112th Avenue N.E. Bellevue, WA 98004 Attn: Vince Ferrese SUBJECT: Valley View Estates Building Permit Application 'City of Tukwila File Numbers 82 -093 and EPIC- 180 -82 Dear Mr. Ferrese: Per our meeting on June 16, 1982, the City of Tukwila has been proceeding with drafts of a possible agreement between the City and the applicant Allenbachs. In our discussion of July 9, 1982, I indicated that the attached draft agreement would be sent to you early this week. We agreed to meet July 20, 1982, after you have had a chance to review this draft and the City Attorney has completed his review of the City's legal position and interests in this matter. I have scheduled a meeting for 3:00 p.m. here at City Hall. If that is not convenient for you, please call my office and reschedule with my secretary Becky Kent. Sincerely, . L . Bradley J. Collins Planning Director BJC /blk attachment xc: Larry Hard, City Attorney Joel Haggard 1. AGREEMENT (Preliminary Draft) V -``o'er Wh mss, applicant has filed an appplication for a building permit (File a; 82 -093) for "Valley View Estates "; and Whereas, in the event that e<ty agrees to proceed with the preparation of an E.I.S. regarding the ()Sett described in Building Permit application File No. 82- 093 /EPIC- 180 -82 O and called "Valley View Estates "; the parties agree to the following: This agreement between the City of Tukwila (hereinafter "the City ") and the building permit applicant Dr. Herman M. Allenbach, (hereinafter "applicant ") is entered into on , 1982. Applicant agrees to place ten thousand dollars ($10,000) in a trust account, which account will be called "Trust Account of the City of Tukwila in Trust for Herman M. Allenbach." The [who can sign] Funds from the trust account may be used for thefollowing costs and expenses, in a reasonable amount at the discretion of the Tukwila Planning Director, who is the Responsible Official of the Lead Agency: • (1) Material and labor for drafing the Environmental Impact Statement, producing the required documents, copying and distributing the draft and final E.I.S., coordinating any technical studies, attending meetings,and presenting the E.I.S. as necessary. ) Material and labor for technical studies including but not limited to: transportation /traffic, noise, air quality, soils, hydraulics, utilities, and fiscal impact. ( The Planning Director may require the applicant to provide data and information which is not in the possession of the City relevant to any or all areas to be covered by the E.I.S. per TMC 21:04.100. It will be the responsibility of the applicant to cover costs reasonably incurred by the City in the preparation of the E.I.S. This agreement advises the applicant of the. projected costs of the E.I.S. It is understood and agreed to by the parties that in the event that the reasonable cost of the E.I.S. preparation will exceed $10,000y`.the :applicant will be obligated to pay that excess amount upon demand by the City. It is understood and agreed to by the parties that if the reasonable cost of E.I.S. preparation is, in total, less than $10,000, the City will refund the balance of the trust fund to the applicant within a reasonable period of time. The Planning Director may determine that the City will contract directly,,; with a consultant for preparation of environmental documents in lieu of assigning City. staff. Such consultants shall be selected by the City afters' requests for proposals in consultations with the applicant. This agreement will become effective when signed by both part es'and upo the deposit of $10,000 by applicant in the above described tr;us`. count. FA. LESOURD WOOLVIN PATTEN DONALD D. FLEMING GEORGE M. HARTUNG MEADE EMORY LEON C. MISTEREK DWAYNE E. COPPLE THOMAS O. McLAUGHLIN JOHN F. COLGROVE C. DEAN LITTLE LAWRENCE E. HARD RODNEY J. WALDBAUM BRUCE G. HANSON RICHARD P.MATTHEWS D. WILLIAM TOONE DANIEL D. WOO LESOURD, PATTEN, FLEMING, HARTUNG & EMORY ATTORNEYS AT LAW 3900 SEATTLE-FIRST NATIONAL BANK BUILDING SEATTLE. WASHINGTON 98154 TELEPHONE: 12061 624-1040 TELECOPIER: 1206) 624.3087 TELEX /TWX: 910 444 -4180 CABLE ADDRESS: LESOURD LAW June 21, 1982 Mr. Vincent Ferrese Mithun Associates, P.S. 2000 - 112th Ave. N.E. Bellevue, Washington 98004 RE: Valley View Estates Dear Mr. Ferrese: CARL J. CARLSON P. WARREN MAROUARDSON LAWRENCE A.M. ZELENAK JULIE G. WADE MARIANNE SCHWARTZ O'BARA DANIEL W. FERM WILLIAM S. WEINSTEIN PATRICIA A. FOISIE ROBERT L PALMER ARDEN C. McCLELLAND COUNSEL Brad Collins, Mark Caughey and I were pleased to meet with you on June 16 to discuss Mr. Collins' letter of June 3, 1982, regarding Valley View Estates. I trust that your questions were answered to your satisfaction. Also discussed at that meeting were some preliminaries to the possible in -house EIS preparation which may occur regarding the property in question. As we all agreed at the start of the meeting, no commitment was made by the City of Tukwila to proceed with the SEPA process. At this time, Mr. Collins has stated that the City cannot issue a building permit based on the application as submitted. If, based on legal advice, the City decides to accept further submittals, an EIS will be required. Although proceeding with SEPA is only a possibility, the City is willing to spend time to enter into preliminary negotiations regarding areas such as scope, technical studies, and costs. It is my impression that the following occurred at the meeting: You agreed, on behalf of your clients, to enter into pre -draft consultation even though the SEPA process may not begin. In a general manner, the scope, technical reports and costs were discussed. You, on behalf of your clients, indicated willingness to expend money now in spite of the fact • Mr. Vincent Ferrese June 21, 1982 Page 2 that the SEPA process may not take place. Drafting of possible documents is to be initiated by the City. No formal agreements were reached. Sincerely, LeSOURD, PATTEN, FLEMING, HARTUNG & EMORY at-1 CA ��� Q. Patricia A. Foisie PAF /mmp cc: Mr. Brad Collins Mr. Mark Caughey Mr. Joel Haggard Dr. and Mrs. Herman Allenbach 1 2 3 4 5 6 7 8 9 10 11 12 13 14 16 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 '07 .t • -10- is accomplished by the responsible official of the City transmitting a notice of the transfer together with any relevant information available on the proposal to the appropriate state agency with jurisdiction. The responsible official of the City shall also give notice of the transfer to the private applicant and any other agencies with jurisdiction over the proposal. Section 9. ENVIRONNEENrAL CHECKLIST. (1) Except as provided in WAC 197 -10- 300(2), a completed environmental checklist, or a copy thereof, substantially in the form provided in WAC 197 -10 -365 shall be filed at the same time as an application for a permit, license, certificate, or other entitlement for use not specifically exempted herein. No application shall-be considered ..complete without the Environmental Checklist. This checklist shall be the basis for a determina- tion by the City as to lead agency status and if the City is determined to be the lead agency, then for the threshold determination. (2) For all proposals for which the City is the lead agency, the responsible official of the City shall make the threshold determination pursuant to the criteria and procedures of WAC 197 -10 -300 through -365. Section 10. PREPARATION OF EIS. (1) The draft and final EIS shall be prepared either by the respon- sible official or his designee, or by a private applicant or a consultant retained by the private applicant. In t nt the responsible official determines that the applicant will be required to prepare an EIS, the applicant shall be so- totified"immediately; after completion of the thres- hold determination. • (2) In the.event that an EIS is to be prepared by a private applicant, the responsible official shall assure that the EIS is prepared in a responsible manner and with appropriate methodology. The responsible offi- cial shall direct the areas of research and examination to be undertaken, as well as the organization of the resulting document. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 (3) In t e v t that the responsible official or his designee is pre- paring an EIS, the - responsible official maykrequire -a private - applicant tro provide_ data -- and-- information which is not in the-possession of- the _City- - - -- relevant to -any or -all areas to be covered by the EIS: (4) No matter who participates in the preparation of an EIS, it must be approved by the responsible official prior to distribution. Section 11. ADDITIONAL ELEMENTS TO BE COVERED IN AN EIS. The.followin additonal elements are part of the environment for the purpose of EIS content, but do not add to the criteria for threshold determinations or perform any other function or purpose under these rules: (1) Employment (2) Economy (3) Tax base (4) Cultural factors (5) Quality of life (6) Neighborhood cohesion (7) So itgical factors The responsible official shall, at the time of making a declaration of significance, ;designate which-of: -the foregoing additional - elements shall. ,be.required-to be; included in:the EIS contents in :order-,to fully carry out, the' polw c,ies: of the,.:Stateis,En*inTorit-ridntralk#POiltirdrAdVfalkliiitlitridikkanee, except for economy, which shall be included in all EIS's as required per Senate Bill 3097 (Ch. 117, Laws of 1975 - 1976, 2nd Ex. Sess.). Section 12. DESIGNATION OF OFFICIAL TO PERFORM CONSULTED AGENCY RESPONSIBILITIES FOR THE CITY. The Planning Department shall be responsible for the preparation of the written comments for the City in response to a consultation request prior to a threshold determination, participation in predraft consultation, or reviewing a draft EIS. Section 13. DESIGNATION OF RESPONSIBLE OFFICIAL. -14- 1 may be commenced after the expiration of the applicable time period for gov- 2 ernmental or nongovernment projects. 3 Section 16. ENVIRONMENTAL POLICIES. 4 • (1) The `City of Tukwila hereby adopts by reference the general policie- 5 of the State Environmental Policy Act (SEPA) as set forth in RCW 43.21C.010 6 and RCVI 43.21C.020. 7 (2) The City of Tukwila hereby adopts the following local policies 8 which pertain to .the physical development of the City: 9 (a) The (goals_, objectives; acid policies of_ the Comprehensive-Land Use. 10 Policy Plan -as adopted -by Ordi,:nance #1039;-and: _:as- may be amended; in the 11 future by revision or addition of plan elements; 12 (b) The goals and policies of the City Shoreline Master Plan as adopt 13 by Ordinance #898 and as may be amended by resolution or drdinance in the 14 • future; 15 (c) Any other policy plan or document officially adopted by the City 16 either by resolution or ordinance which is related to the physical or social 17 development of the City. 18 (3) The decision of the responsible official to condition or deny any 19 proposal shall be based upon the environmental policies as stated in subsec- 20 tion (2) above. The written decision of the responsible official shall 21 reference the applicable policies, as required:.in Section 14 of this ordi -. 22 nance. 23 Section 17. RESPONSIBILITY OF AGENCIES - SEPA Public Information. 24 All documents required by the SEPA Guidelines shall be retained by the City 25 and made available in accordance with Chapter 42.17 RCW. 26 Section 18.' FEES. Fees shall be required for actions by the City in 27 accordance with the provisions of this Ordinance and in the amounts provided 28 for in current City Ordinance establishing fee schedule. 29 (1) The -City_ may • requite a fe -e for, 7every - environmental_, checklist -and') 30 directly_ related- items- filed7wi _th--t}id-City- _when:__the:C ty is the:lead agency? 31 32 1 2 3 4 6 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 Said fee shall be included in a general fee ordinance. (2) Environmental Impact Statements. (a) For all proposals requiring an EIS for which the City is the lead agency and for which the responsible official determines that the EIS shall be prepared by employees of the City, the_ City may charge and collect a) reasonable _fee from any applicant to" cover costs incurred by the City in the, preparation of an EIS. If it is determined that an EIS is required, -applis cants shall be_advised_of projected costs -of the-Statement-prior to actua 'preparation and shall post bond or otherwise -insure payment-of-such costs/4 (b) The responsible official ray" -determine- that -the City wi11-;contract. directly with a 'consultant for preparation-of environmental-documents for activities initiated by persons or "entities other than the City and magi, bill such costs and - expenses directly to the applicant: Such consultants • shall be selected by the -City after requests for proposals -in-consultations, with the applicant_: -- Applicants -stay be required to post -bond or-- otherwiset" insure_ payment. -of -such costs. '(c) In the event that a proposal is modified so that an EIS is no longer required, the responsible official shall refund any fees collected under (a) and (b) of this subsection which were collected for costs not incurred. (3) No fee shall be collected by the City for performing its duties as a consulted agency. (4) The City may charge any person for copies of any document prepared pursuant to the requirements of this Ordinance, and for mailing thereof, in a manner provided by Chapter 42.17 RCW. Section 19. NOTICE /STATUTE OF 'LIMITATIONS. (1) The City, as applicant for or proponent of an action, may publish notice of action pursuant to RCW 43.21C.080 for any action. (2) The form of the notice shall be as prescribed by the Department of Ecology and /or substantially in the form and manner set forth in RCOI MIS I9 A LEGALLY BINDING CONTRACT. READ BOTH FRONT AND BACK CAREFULLY ULI OI1L SIGNING •(VACANT LAND FORM) Des MoirieS Washington N9Ve9T1ber 23, — . 19 81 - 11,,, tiircielr;igtu,d Buyer Herman M. & Veloy S. Allenbach, Husband & wife & /or Assigns and .Seiler agrees to sell, on the following terms. the property commonly known as / at / near S. 160th & 53rd Ave S. - ._ in the City of Tukwila Kinq County. Washington. legally described as: Lot 7, Block 1 Nkndcken Heights Division #1 unrecorded, less the East 170 feet less State Highway • •• (Buyer and Seller authorize agent to insert and /or to correct, over their signatures, the legal description of the property.) • 1. PURCHASE PRICE. The total purchase price is 3. S fl 4. All cash on closing including earnest money. ($ 5,600.00 lars -- ) payable as toiiows ,rted-K;•t5-eour,t ,• Pt t. on 5. CONDITION OF TITLE. Title to the property is to be free of all encumbrances or defects, except• None Rights reserved in federal patents or state deeds building or use restrictions general to the area; utility and other easements not inconsistent with Buyer's intended use: and reserved o;' a :nirrerai rights; shall not be deemed encumbrances or defects. Encumbrances to be discharged by Seller shall be paid from the purchase m,:'e: at the date of closing. =se IF nort h;,. -. .-days-fronr eni-- het -any -utr♦it f IE ronEGOING, it IS ,I,c PL Ief A.SEFI'S n:ZPONStS1L+'': TC V«_ 7. CLOSING OF SALE. This sale shall be closed on or before march 19, 19 gam_ by —Transamerica--Title' or such other Closing Agent as Buyer shall designate. Buyer and Seller will. rmmec.ateiy on demand, deposit with Closing Agent all instruments and monies required to complete the purchase in accordance with this Agreemer: 8. CLOSING COSTS & PRO - RATION. Seller and Buyer shall each pay one -half of escrow fee. Seller shall pay for the real estate excise taa : c revenue stamps. Closing year taxes, rent, interest, mortgage reserves. and utilities constituting liens, shall be pro -rated as of closing. 9. POSSESSION. Buyer shall be entitled to possession on closing. "Closing" means the date on which all documents are recorded and the sale p-;.• ceeds are available to Seller. • 10. DEFAULT AND ATTORNEY'S FEES. In the event of default by Buyer, Seller shall have the election to retain the earnest money' as liquidated dam- ages, or to institute suit to enforce any rights Seller has. In the event that either the Buyer, Seller, or Agent. shall institute suit to enforce any rights hereunder. the successful party shall be entitled to court costs and a reasonable attorney's fee. 11.. SPECIAL PROVISIONS. THE FOLLOWING PROVISIONS ON THE REVERSE SIDE HEREOF ARE PART OF THIS AGREEMENT: PURCHASERS INSPECTION; TITLE INSURANCE; CONVEYANCING; GENERAL PROVISIONS; CONDITION OF WELL; and (if applicable) COUNTEROFFERS. 12. EARNEST MONEY RECEIPT. Agent acknowledges receipt from Bu er of 1, 000.00 9 _ 9 P X $ in the form of ❑ cash ,�" personal check ❑ cashier's check y -- - -- - -- --- - -_ --, . c as earnest money. AGENT Lascn & 13. AGREEMENT Seller shall Agent. If thi BUY, rtes Tnc BY `1John P_ Lason URCHASE —AND TIME' LIMIT ntil midnight of Nov fer �s�not $6 acce 17/ tei •ted Fr, ADDRESS: HONE: Home ‘? ' �`� Office R ACCEPTANCE. Buyer offers to purchase the property on the above terms and conditions 25 19 81 to accept this offer by delivering a signed copy hereof to the laps nd t JAgent shall refund the earnest money to the Buyer. // / • 14 SELLER'S ACC TANC- -E n.:; ND BROKERAG AGREEMENT. Seller agree- to sell the property on the terms and conditions specified herein; a �` Ten Per Cent further agreed to pay a commission ot� ($ to the Agent for services rendered. If earnest money is retained as liquidated damages, any advances by Agent for Buyer or Seller shall be re -rm- bursed and the'balance shall be divided equally between Seller and Agent. Seller acknowledges receipt of a copy of this agreement. signed by both parties. _ SELLER 1 SELLER PRINT SELLER'S NAME(S): PHONE: Home - Office DATE ADDRESS• • .% •,• . ., . • •,4 15. BUYER'S RECEIPT. Buyer acknowfedges'r,eceipt of, arSeier; Signed copy of this a BUYER BUYER MLS ^CSIGNED 5/78 mpnt, on _; 10 / • MIS CODE NO. LISTING AGENT . • S: i'iOKEg'S COPY AGREEI T FOR EXTENSION OF CLOSOF ESCROW The undersigned Purchaser and Seller, having heretofore executed an Agreem nt of Sale dated NrwU1 er 23, 1982 xffxx trlllil(r III Illy rr. -11 IlroptIlly siln�ll:d in Illy City III `I - -44 riT'Ie5s , County of King State of Washington tlt ctil�utl.IS IA.A. II 1, Ii1 . .I Mtl�lltktal 11ii lltl:: I�ivi.:clutt 1-11 tnu*xt,l.(.k.x.i, .11:;:: llu• 170 feet less State Highway hereby agree to extend the period for close of escrow until midnight of May 3 , 19 82 Other dates set forth in said Agreement of Sale shall be extended as follows: All other terms and conditions of said Agreement of Sale shall remain the same. 3 -18 -82 Dated. Purchaser .- / teaser Seller Agent Agent By By Broker Broker FORM 118 (2- 1e -72) ©COPYRIGHT, 1972. BY PROFESSIONAL PUBLISHING CORP.. 12; PAUL DRIVE, SAN RAFAEL, CALIFORNIA 9.9C7 ft� PROAaawnu MIWJ�N184 CORPOUTKM1 • • AGREE NT FOR EXTENSION OF. CLOSIIIIOF ESCROW The undersigned Purchaser and Seller, having heretofore executed an Agreement of Sale dated liavarther_23, , 19.81., relating to the real property situated in the City of ...Tukwila , County of King , State of Washington described as ..14t..24...131ock.1..of Nii.cic.en _Heights .12trisionn #1 __Unrecorrled,.. less.. the east 170 feet less the State Highway hereby agree to extend the period for close of escrow until midnight of July..94. ,1982... Other dates set forth in said Agreement of Sale shall be extended as follows: . . • All other terms and conditions of said Agreement of Sale shall remain the same. :2 4W Purchaser Dated. April 29, 1982 PAL- eller Seller Agent Agent By By Broker Broker FORM 118 (2-16.72) ©COPYRIGHT. 1972. BY PROFILISSIONAL ru•LismiNG COR•.. 132 PAUL DRIVE, SAN R AAAAA CALIFORNIA 54903 PRORESSOCIal COOPOILII1100 18.60.200 Recreation space in multiple - family distric In all R -2, R -3, R -4, and RMH zoning districts, any proposer multiple - family structure, complex, or development shall pro- vide on the premises and for the use of the tenants a minim amount of recreation space according to the following provi- sions: (1) For each proposed dwelling unit in the multiple - family structure complex or development, a minimum of two hundred square feet of recreation space shall be provided_ Any multiple - family structure, complex, or development shall provide at least one thousand square feet of recreation space. (a) No more than fifty percent of the required recre- ation space may be indoor or covered space. • (b) No more than. f i f ty percent of the required space may be used for single - purpose permanent facilities such as Secti The t (whet the c sion swimming pools, tennis courts, and similar facilities._(;;.e. = �ucs . ) Noi LJ Apartment complexes which provide dwelling units in t? mvr. with two or more bedrooms shall provide adequate recreation inju space for children. Such space shall be at least twenty -five confc percent but not more than fifty percent of the total recrea- clud: tion space required under subsection (1) above and. shall be designed,.located, and maintained in a safe condition:, Ord. (d) No more than fifty percent of the .open or. un- covered recreation space requirement may be located -on slopes greater than four horizontal to one vertical (four -to -one slope). 18.6 (e) The front, rear, and side yard setbacks required by the applicable zoning district shall not qualify as recrea- dist tion space. • (f) In the event the total area required under sub- section (1) above is less than three thousand square feet, that portion required to be outdoor and uncovered shall be one continuous parcel of land. (g) Adequate fencing, plant screening, or other ' buffer shall separate the recreation space from•public streets, parking areas, or driveways. mar (2) It shall be the duty of the planning commission, acting as a board of architectural review, to review all' recreation space plans for design, location, function, ade- quacy, and compliance with the above - stated standards prior to issuance of the building permit for any multiple - family structure, complex, or development. (Ord. 1040 §3, 1977). 308 -1 (Tukwila 12/15/77) limi vert trac leum buri tric nark insE tior ing ria: • , :VeU.r✓ V0// .- - r-4T14 - AL Tr/A.C.- I8. 6o . Z-0 c7 �1. Dif Top& - izec, 3f - e..traNeeo = dos 0141rs x Wo cf = o4o0 t - -r ;.' /ILt? .e 101 }( 5270 /k17( -1N AU 2W U� I o� S-Oo 12E04 A.6Gwls 4 X /eve,. Lot y 15 3� " P62, rp(L C!1ILpR P 5 paZ1 A> = 5440 c�? ) 6070 0r ` arrai Mk d t5% sLoft 1.3 9.$` 5400 tf (TI Fier) 35406(0'7 t7 s58.37 • �-i w a po ft o1n 3540067 THZ G1tANTOR8, DK GRIMBLEY -and MARGUERITE GRIMBLEY !, his wife, = fir i.a 1: m aetltfer — Pnsr'8iuttilre6' ireiti- ti`vi —i i3"6/100 - 1011„, - (II 426.00 _).. ••W!d paid, Convey /+m arananitto _MERVILL STEVENS , site following described red mats, situate in the Canty of ' K 1.. N G State of Waiiugwn: . •• Beginning Ht the northerist corner of the nurtnv:est quarter of'the nort:.i.cst quhrt.:r of eeotion twenty-11z (26), town- ship twenty -three (23) north, range tour (4) east ••s • and atom u-ner-ear aim,- or sari northe.eet quarter of ti.e north%est quarter, south -0009' ' east u9.60. .feet; thence :.:.rth 89 °31'13' west 614.81 feet along a line parallel to the ^orth.line of the northveet quarter c(. said section; • tnenc'e north 21010'20' west .74.76 feet to tt:e north line of the n;.rtr. ^est quarter of said section; thence south U90b1'131 e;st .ssia•nort)r line, 641.63 feet to the point of beginning; • •� (Being i nown as lot s even (7)', bloca one (1), wc, lcken . Heights Division . %o. 1, aocordin,; to the unrecorded plat tnereof). • this .'.'lnd day of June, ,A.D.1945. (Seal) . STATE OF WASHINGTON. On this•dtiy_p oaigj appeared Wore me D. K.• .'rimeley and. Marguerite Lirlcesley, hie wife, • to we knows to be the individiuI s described in and who_c setvoed- the_wfthin_and- foregoing- inetroe>ent, -and - `ultmisita Id flue._. they signed the same as .their free and iolentary act and deed. for the • mss acid penibscs therein mentioned. • nadir my hand and official seal this Aril, of June,, .46. • 5372503 mervill stevens statutory warranty deed 9 ' , pipeline try dssd s a�rdat ens last 171 foot of fps Soliowlso dsaarlbod test of„la s ' -. 1 at tbi Iloedrast sonar 1/4 t►lt r M ; lmo! istdo t a 4 r1 of doe host! mast 1/4, �� i Nowt 4!•31'13" V.st f+Ui.$1 • 4 1 Borth 11w of ielre* st of. 11•21" Most 74.71 foot to Ste N said Swiss; Osseo Soo* N• ` x. i 341.13 foot to the Ositt of 3 '+ 171 fast of Lot 7 l• 4lNk 1 as ru+soosdst plat); _ - 5372503 mervill stevens 5655837 WARRANTY DEED In the Natter of Primary State Highway No. 1, South 178th Street KNOW ALL MEN BY THESE PRESENTS, That the Grantor to South 126th Street f MERVILL STEVENS, as his separate estate and other va ider a caoside runs of • • - TEN and N0 /100 - - - (510.00) - - - Dollars, hereby convey s and warrants to the STATE or WAStnxsron, the following described real estate situated in King same extent and purpose as if the County, in the State of Washington, to the e rights herein granted had been acquired under Eminent Domain statute of the State of Washington: All of the following described Parcel "A "; EXCEPT that portion lying westerly and southerly of the following described line: Beginning at a point on the southerly boundary of said Parcel "A" and 235 feat westerly, when measured at right angles from the bl Ilene center line of Primary State Highway No. 1, South 178th Street to South 126th Street; thence northerly parallel with said center lino to a point 45 feet southerly from the northerly Parcel "A" Aofto said Parcel thence way ppafrallel with sold northerly line of said Avenue along said right of way line to its point of intersection withh the ncrthorlyrboundaarylline of said Parcel "A ", and the end of this line description. PARCEL "0 ": Beginning of the northeast corner of the northwest quarter of the northwest quarter of section 26,tmwnship 23 north, range 4 east, M.M., in King County, Washington; thence along the east line of said northwest quarter of the northwest quarter, south 0 °09'36' east 69.50 feet; thence Borth 89°31'13" west 614.81 feet along a line penile, to the north line of the northwest quarter of said section; thence north 21°10'20 - oast 74.78 feet to the north line of the northwest uarter of said section; thence south 89 °31'13" east along said north lino 641.63 feet to the point of beginning; EXCEPT the east 170 feet thereof; (Being known as Lot 7, Block 1, McIicken Heights Division No. 1, according to the unrecorded plat, EXCEPT the east 170 feet thereof). Tho lands being conveyed herein contain an area of 24,50J square feet, more or lost, the specific details concerning all of which are to be found within that certain map of definite location now of record and on file in the office of the Director of High- ways, at Olympia, and bearing date of approval January 30, 1962, revised August 20, 1963, and the center line of which is also shown of record in Volume 2, page 200, of Highway Plats, records of King County. • ,1',1 1 .Vt% .!, e3 • YH I MES"'%HI • • • •�I' KVTAH1 • 1 It is understood and agreed that the delivery of this deed is hereby tendered and that the terms and obligations hereof shall not become binding upon the State of Washington unless and until accepted and approved hereon in writing for the State of Washington, Department of Highways, by the Chief Right of Way Agent. Dated this_ 26 . day of_Septerisrp_1963 ..fittit-44.e/ Accepted and approved_/‘...)"..4. STATE • WASHINGTON if • HIGHWAYS By. Ctilef Right of Wiz; Asest.„7 STATE or WASHINGTON. County of._ King 1, the undersigned, a notary public in and for the State of Washington, hereby certify that on this 26th . _day of... lirlsobar, 1463 _personally appeared before vise G. Storms to me known to be the individual__ described in and who executed the forego.ng instrument, and acknowledged that_ he . signed and sealed the same as. his free and voluntary act and deed, for the uses and purposes therein mentioned. Given under my hand aid official seal the day and year last ,fit • Public Wend f Slav af Washingolk (1 co .. in a g is :I) ir) " 'OCT 24 1963 RECORDED VOL . PAGE .......... 1963 11,4. • 24 ' ROPEAi c-• "hrY r145q RtSiding at Seat t , 1 t . • „ - "e, , • \ • 41. 1 ')1 Ni ,\ ,USUSSOR I• ET., r.:1-4".■ • ",- ! • , ' ''• I:7;7 . - • ••• 145) a 4 .04 NW 26 23 — 4s SCA LE 1 a 400' o '970 .1)0 na• 54.0 ro 1 ■40 SC. 1 0 „ „ I I0 2 .01 — _ 4.0 r__141- LI :sr If 9 Ro•O L." assoiro0.4i 12 : .p.o.v. bv, lilao 0643 g 00 00.' • v. lb 4614 4411 4 04'1 4 SOD•Ve 4 0 0 0 e %0„1, • do a $3 — s a • • 0.0 K1 0 INO • do. *Oat z1 4 —11•1241, 9 16340. PL. oi aa�p a 2.000 1 H 1570.80 1 61,110 54151.132 21820.70 TOTAL AV IS1Y SOFT YR DEL lITAR wi1�6°.% 3 1 X03 1440 09 537620 -MC LELLANS ADD 0005-- 06OCARL�VEEP& TLE WA 98136 7150 45TH AV 5W 0010 -09 TOOMIr4TER NE VF 7144 45TH Av SW 7144 45TH AVE 5 WSEATTLE VA 98136 0010 1 1 • sw-26 0010 1 SFD 1 2r 514- 26 -24 -03 D2 SEATTLE * * * * * * * 18,600 49,600 1610281.0e 1920 48 18,600 42.900 65491.08 2120 48 WASHINGTON REA%1.1ESTATEIREGISTER BELIEVES THE INFORMATREGISTER, N 14 TOCBESCORRECT WASHINGTON 1 00E NOT0WARRAN131T5 ACCURACY. THIS INFORMATION 1S LEASED FROM AND REMAINS THE PROPERTY 01 WASHINGTON REAL ESTATE REGISTER. INC. 537620-MC LELLANS ADD ACC1 -NO OWNER NAME MAILING ADDRESS 0015 -04 KOROIAK JOSEPH N 7138 45TH AVE S•SEATTLE WA 98116 0020 -07 HAW HENRY 7132 4144 AVE 5 WSEATTLE WA 98116 0025 -02 MANGINI GEORGE R 77 451H AVE S•SEATTLE WA 98136 0026-01 KWA51 JULIUS 7145 45TH AVE $ WSEATTLE WA 98116 0035-00 T110TTER, 10981E LESTER JR 7 51 45TN AVE SWSEATTLE WA 98136 537920 -MC MICKEN HEIGHTS SEATTLE S1TUS ADDRESS 7138 45TH AV SW 7132 451m AV SW 7137 45TH AV SW 7145 45TH AV SW 7151 45T4 AV SW 000} SCHM1D ALFRED 1 5 TAYLOR AVE N 0101•SEATTLE WA 98109 0006 -02 SCM1D ALFRED 1 5 TAYLOR AVE N *SEATTLE WA 98109 0010 -06 PUGET WESTERN INC PUGET POWER 8LD80IELLEVIA: W 98004 0015-01 PUGET WESTEN NC PUGET POWER ILD8.8ELLEVUE W 98004 �30� JOEY POMP STEM INC _ _ W 230 0 1040J0 AVE.E00JACK S WWA�98020020 0060-05 ITER LEONARD G JR 16024 SS11ST S *SEATTLE _j`TAL /1 A TV OSTY SOFT TI �e 2144 2, 2200.43 220,97 54174 87 �nN1.18f 1560.65 21110271.08 1920 05 361.01 1920 0$ 1T60,bs 11571°.12 36.30 WA 901884 0061-04 LAWRENCE THOMAS E 16010 1601..y�551ST AVE S ►SEA TLE WA 98188 �2.1p6601t4 1511iTWAYE SSEATTLE W 98188 16014 °� 160300S1STTAVE $' UATTLE WA 98188 16030 0067 -08 0001011 JACOUELL,,FE K 16036 7p1p6036 5151 AVE S *7!111!.1 WA 98188 00 31131 AMMU IOSTOST SE•OLYMIPIA WA 98501 410711605NOSTSTKAVSES SEATTLE WA 98188 VOL 45 P; 5 LEVY 1 USE uN L01•BLOCK 0- 5- T- R 0010 1 SFD 3. SW -26 -24-03 0010 1 SFD 4. 5W -26 -24-03 0010 1 SFD 5- SW- 26 -24 -03 0010 1 SFD 5-6. 5W- 26 -24 -03 0010 1 5F0 T. 5W- 26 -24 -03 DIV # 1 UNREC 5300 AV S S 160TH 5T i 53RD AV $ 53RD AV 5 53RD AV 5 53RD AV S 51ST AV S SIP Av S 51ST AV 5 51ST Av S 51ST AV S 16050 5151 AV $ 2320 202 10w-26-23-04 53RD AV 52320 902 1.1 NW -26 -223- -024 3.12N4-26 -23-04 2320 202 4.1 Nw26 -2231 -204 50 N3A-26 -23-04 � 6S -23204 1•22N3220-26 -23-04 2320 1 F0 4 1.2 NW-26 -25S3 -00 1•2 4126-23 -04 SOLD PRICE LAND 4MP 1011E AV 0S11 SOFT 11 LEGAL DESCRIPTION 115 DEL 81111 1 7005 27,500 18,600 48,200 66.600 1.08 1920 49 119 566.19 1 20.100 47.300 67 400 1.08 2120 49 ppr, 601.54 710 F1 22,000 23.300 45.500 68,800 1.08 2180 49 LESS 5 614.04 1 20,100 46,900 67 000 1.08 1840 48 5 10 F1 01 5 1 ALL 6 57.07 1 7408 27.500 18.600 50,800 69,40Q_1.08 2180 49 69.3 COUNTY * * * *pp * * * LESS FOR 8EG AT SE C0R 114 4*.!0I175 FT TN 1p579 112123.32 P0R BEG AT SE C0R TN 4*.Y 174 TN W PLTSYR 338161.181 LOT 3 811 1 i P011 VAC CO RD LESS PARCEL 10976.80 i FOR VAC RD LESS PARCEL i /6R00PARCELS PER U 2190554 1 P0R VAC RD i POP VAC NO ADJ00LOT 6 LESSOPA 1098 LESS E 170 FT 1E55 5T HW7 2.500 0 22440.42 1 7610 52 000 12.300 76.100 S 80 FT OF W 120 (T 161 • b3 491.41 2990 73 1 7305 29 500 741.08 2280 62 P01 OF W 150 F1 0f NW 1/410i52 1/451(1.i72601 LESS W 120 F1 i N 20 FT 0165 100 115013w°12 2•22NW0-26.123F -004 PARCEL 8 OF TUKWILA SP 792442 -1515 REC4MIb2 2.22 *4- 26-23 -04 PARCEL8A004 TUKY814AOSP 79-43 -55 REC5446 2320 1 7712 10.300 3.2 NW -26- 25g3-04 E 150 11 3.214122612304 14 150 FT OF S 70 FT E2 2 66110131.0 1790 62 6 ;110131.0 1240 60 65•;00.1.0. 2660 40 0 tObi1 12.900 50,700 00 651¢0041.0. 1980 SS WASMINGTOTNIS {��IONi� TIE D 8011 A �ORIFNIST1i IS14.014 0 0 CORNEC1t 010 00TEQSMINOT204REGANTEATSIAACC CURACY. 537920 -9C MICKEN HEIGHTS DIV 0 1 UMEC COUNTY ACCT -PC MINER NAME QQ�2.p� 1MW11LING ADDRESS 160101151 AVECS SEATTLE W 98188 16044 SI1U5 ADDRESS 10202 MI AVE SEATTLE VA 98188 (16764410 51�Sp1FN*141 US•*S►EAAITLE WA 98188 0 - 11�1s11A88TN.SEATTLE WA 98188 116210 S11TFAV1ME SSEATTLE W 95188 16202 16210 16226 16218 9114 S1iT AVE11001EATTLE WA 98188 16256 *".722,01f1 SOSEATTLE WA 98188 (111°M111111111 PIMEO L 16418 AYE 1OSEATTLE WA 98188 0 1 1 1111 4 4� 1121-*141 SS•' 1�TTLE W 98188 16444 011 Ali - 111999 $ 11MM1N• RUKW1lA W 98188 0111441 f11tEMWCE� R c80 TATLTLE WA 98188 16428 011f•00�/ 5117711 AAt1E11*SEATTLE WA 98181 16430 5151 Av 5 5151 Av 5 51ST AV S SISI AV S 51ST Av S 51ST AV S .,I51 AV 5 5151 AV 5 515T AV S 5151 Av 5 LEVY 2 USE UN SOLD PRICE L0T•BLOCK 0- 5- 1- R 3.224 2 21026- F -04 LESS E 4.22N?1�26�2gS33F -04 14 1/2 LEGAL DESCRIPTION 4.22g226!2124 04 511 /2 5.2241226 -25S3- -904 511/2 5.2241 26- 2SS3p -04 14 1/2 7.224126-23 -04 511/2 LAND IMP YRS 30,600 159 FT LESS S 70 FT2DKR 17,400 17,400 17,400 7101 8,000 17,400 43,900 27,200 31,700 26,300 TOTAL AV 0STY SOFT YR DEL 81TAK 4!,50111.5 1330 40 .'. 6 61.3061.08 1880 57 442299#651.08 1880 31 49L100 1.08 2120 43 479.61 44700.1.08 1480 43 44 80008661.08 2040 37 437'.61 1033101061 00 55210.871.58 1840 30 51;00111.05 1800 42 2xx 1 14..442 00 LESS POR PLATTED PLEASI� HEIGHTS 2 2320 1 8-9.2 NW- 26 -2gs3� -004 14 100 FT 01 8-9.224126 -23-04 11100 F1 1 9- 10.2243211026- 23F-04 2320 1 9.2 NW- 26.23 -04 FOLG S 46.67 11 00 1 8 L N 53.471 OF W 200 FT OF 5144367 pp0 FT 0F,8801 E 13, SO ;2494 900 41,800 101 LESS 2p11 TGW N 22. 802,7 O1 N 134.33 FT 0 5171.67811 OF 7110 E 317 FT OF 5 9.22N126-123 -04 5180 F T N 1 4311 18$$ 10317 P1311155 W 91110242.0 2050 79 02320 1 510 1 7411 •x uu -xA -x .J'L C .0 ., 141841°9. e• nc ..124 2(1 -- 631600 _ ?S, 20Q_1.08 2570 74 0920-02 PRICE OREN A 16205 42ND AVE S•SEATTLE W 0925-07 !I1M1Y1D SNSEAITLI 0930 8ERPA R08ERT C JR 16204 M1L1TAR7 RD 5.5EATTLI ism WASN1NNNMIl *4 E 1 G10 IIIEI 537980 -NC MICKEN FEIGNIS DI ACCT -ND ONNER NAME NAILING ADDRESS 0935-05 GLINDEL COMP 1610 35TH AVE SE•AUBURN W 0940 -08 SENGSIOCK EUGENE E 16219 42 AVE S•SEATTLEE W 9 097601p6221�9 4422SAVEKS•SS1ATTLE W 9 p�q�p- 1162219 42SS'SSEATTLEE WE 98188 16219 4 ND AVEES•�SEATTLE W 0980 -62 C4EVR0N USA INC PR0PER1 PO 8011 7611•SAN FRANCISCO C 1000-03 RrALS JOHN E 16016 341H AVE S•SEATTLE NA 1005-06 ELLIS ALLEN 13330 MILITAR7 RD S•SEATTLE 1010 -01 11687 DEVELOPMENT CO 18601 PACIFIC ANY S 011•5E 1020 -09 R1G8Y DEVELOPMENT CO 18601 PACIFIC HW S 01105E 1040.05 IIRCNWOOD AIR MOTEL LTD 9900 LAKH•300 8LV0■001/Ev co 1050-02 11RC111460D AIR MOTEL LTD 9900 LAKEWOOD BLVD•D01REY G 1090.04 ENK1NS OL1VER E 16033 MILITARY RD.5EATTLE 1100 -02 N*ADA CHARLES 1 7033 S LAKE RIDGE DR.SEATTLI 110112 2ESE 2533TIO.KENT WA 96031 111 KAUT2 ERNEST C 3702 5 162N3 STSEATTLE W 1 1115-07 KAU12 ERNEST C i Dd115 3702 $ 162ND STSEATTLE WA S 1116 -04 REGAN NORMAN 3425 5 176TH 0117.5EA1TLE W 1120.08 KIN D00 YOUNG 3460 5 162ND 5.5EATTLE WA 98 1911 opyoupg WASN1NGTON Utah loN 1 TM1S IiM�ON1A1 1 537980 -01C MICKEN HEIGHTS DIV ACCI -NO OMEN NNE MAILING ADDRESS 1130- 05.81s116280.5EAITLE WA 98181 1140-04040091888E AGNES 3456 5 162MD•5EATILE WA 9818! 1145-09 OREEC AGNES 1 3456 S 16•SEATTLE WA 98181 1150 -01 JENSEN LG 3436 $ 16210.SEATTLE WA 11606636 116144 5E*REMTON W 98055 1170 -8__j COOPER PAUL D 4422 S 16210 - SEATTLE WA 98188 1180.03 WA111 N D 16120 34TH AVE S- SEATTLE W 9 1190.3 111E Opl�l` CO PO IOK 99007*11*174.E WA 98199 1210-09 :111114 U1A NC PROPERTY PO 80% 7611•8AN FRANCISCO CA mown=126011= 1.140 W1 LTD RVD 8!111 2100 1270-06 6001 1401N4ME1 1080146 WA 9805. 1300:00 M P_M115S_CHAROLOTTE __ 0 a us NI11Lq ;1908 City of Tukwila 6200 Southcenter Boulevard Tukwila Washington 98188 Frank Todd, Mayor MEMORANDUM To: Byron G. Sneva, Public Works Director FROM: Phillip R. Fraser, Senior Engineer DATE: 6/1/82 SUBJECT: Valley View Condominiums.- Meeting with Mr. Terry Kostlerich, Val -Vue Sewer District, and Mark Caughey, Planning Department on 6/1/82 Per your request,. . Mark Caughey and I met with Mr.. Terry Kostlerich of the Val -Vue Sewer. District, to gather information with respect to the recent plan review for the Valley View Condominium project. . Mr. Kostlerich look- ed at a set of plans including the plan indicating existing Val -Vue sewer mains with easements. It was his opinion that the easements and sewer mains appeared to be approximately as constructed. He also indicated that the easements were on file with Val -Vue Sewer. District and, that he would send a copy of these easements to Public Works within the next couple of days. When asked if Val -Vue Sewer District was approached by the developer with a plan set such as this or one similar; Mr. Kostlerich indicated that he was not approached by the developer with any plan set, at any time prior to this meeting. However, he indicated that individuals do call without identifying themselves, asking general questions. With respect to the procedure Val -Vue Sewer District would use in such a building site plan on such property, Mr. Kostlerich stated the following, (I paraphrase): the site itself, according to Mr. Kostlerich, has a history of sliding, localized unstable soils conditions and hydraulic problems which would cause Mr. Kostlerich, in the plan review, to have his engineers and /or the developer's engineer carry out extensive engineering analyses respective of the proposed development. For such a plan site review, a minimum of 30 days would be anticipated. The final decision to allow such a development to proceed would rest with the Board, and be dependent on recommendations from his engineers according to Mr. Kostlerich. In terms of requirements by the Val -Vue Sewer District, Mr. Kostlerich indicated that his engineers would provide requirements to allow any building to be placed over the existing sewer easements or mains. Under some circumstances, Val -Vue Sewer District has allowed for either buildings to be sited over sewer mains and /or the relocation of sewer mains to allow for the building developments. xc: Mark Caughey, Associate Planner Terry Kostlerich, Val -Vue Sewer District Larry Hard, City Attorney *ALA .S 4 City of Tukwila J% 6200 Southcenter Boulevard 1 Tukwila Washington 98188 ttl TO: FROM: DATE: Frank Todd, Mayor MEMORANDUM Brad Collins, Planning Director Mark Caughey, Associate Planner 27 May 1982 SUBJECT: EPIC- 180 -82: Valley View Estates This memorandum is a follow -up to the Declaration of Environmental Significance issued this date for the Valley View Project. As provided in Section 11 of Tukwila Ordinance 1211, the responsible official may, at the time a Declaration of Significance is issued, direct that additional elements of review be included in the E.I.S. document. In reference to the concerns identifed in the Threshold Determination Document, we suggest that the following additional elements from the list in Section 11 be included in the Valley View Draft E.I.S. Elements (2) and (3): Economy /Tax Base - The content should be focused on a cost /revenue analysis of extending municipal services or upgrading existing services to this project site which is located at the urban fringe. Elements (5), (6) and (,7).: Quality of Life /Neighborhood Cohension/ Sociological Factors - Currently, there are no multiple - family developments in the incor- porated area of McMicken Heights. The proposed project, if implemented, represents a significant departure from the prevailing low- density residential land use pattern. The social implications and growth - inducing impacts of this project relative to the policies of the Comprehensive Plan should be analyzed. I suggest that we communicate the need to prepare these additional elements in the E.I.S. at such time as a pre -draft consultation is held with the project proponents. MC /blk • • Threshold' Determinati on File #EPIC- 180 -82: Puget Western Condominiums (Valley View Estates) INTRODUCTION The proposed development, consisting of 108 condominium units on 5.3 acres, constitutes a major action within the language of RCW 43.21C.030(e) and as such is subject to compliance with the provisions of the State Environmental Policy Act. An environmental checklist form prepared by the project proponent was circulated to the various departments of the City administra- tion, and a number of comments were received. DISCUSSION The following is a summary, by department, of comments received in response to the S.E.P.A. Checklist: A) Public Works 1) Checklist Section I, Item 11: Future impact of planning by Val -vue sewer District and Tukwila Six -Year Street Plan should be analyzed. 2) Section II, Item 1 (Earth): Historic slide conditions not given satisfactorally - complete discussion; preliminary soil's report gives insufficient details on feasibility of construction bearing capacity and scope of grading. See Fraser letter of 5 -17 -$2 attached. 3) Section II, Item 13 (Transportation): Disagree with statement that increase iniproject traffic will not affect the existing transporta- tion system. The City's Six -year Street Plan recognizes Slade Way to be substandard. Comprehensive traffic study needed per 5 -17 -82 letter. 4) Section II, Item 16 (Utilities): Water service and storm water management demands not quantified - comprehensive study required per 5 -17- 2 letter. B) Recreation Department: 1) Checklist Section II, Item 19: Disagree with negative response on recreational opportunity impacts. No useable recreational facilities provided on -site in relation to the anticipated expansion of neighbor- hood population. Adequacy of recreation space and diversity within the project context needs further investigation. 2) Potential recreational trail connections should be explored. C) Fire Department.:. 1) Checklist Section II, Item 14 (Public Services): Adequate water supply from District #75 facilities for fire suppression purposes is questionable; further study required. D) Police Department: 1) Checklist Section II, Item 13(_c & d): Adequacy of access /site distance relative to increase of project - related traffic on adjoining streets is not clear. 2) Checklist Section II, Item 14(b): Increased population and change in land use will increase demand for police services; impact investigation required. CONCLUSION It appears that there are a number of topic areas which have not been investi- gated to the level of adequacy expected under SEPA. In addition, the Washington State Supreme Court, in its decision in the Norway Hill v. King County Council case (87 WN 2d. 267) articulated a series of criteria under which a Declaration of Significance is obligatory: 1) Change of use type from existing use: In the present case, the site is to be transformed from a wooded, unpopulated area into a suburban multi- family neighborhood, similar to the Norway Hill circumstance. 2) Scale of the project: The number of units proposed in this project is substantial, both in absolute terms and relative to other residential developments in the neighborhood. 3) Degree of change in use: As there is no multiple - family use in McMicken Heights at this time, the proposal represents a shift in the present use configuration of the general vicinity. For these reasons, a Declaration of Significance and requirement for an Environmental Impact Statement in accordance with WAC- 197 -10 -350 is recommended. MC /blk • City of Tukwila 6200 Southcenter Boulevard Tukwila Washington 98188 PLANNING DEPARTMENT TRANSMITTAL DATE OF TRANSMITTAL 4 / 7 / 82- TO: 1SBUILDING DEPT. ❑ POLICE DEPT. ❑ FIRE DEPT. ❑ RECREATION DEPT. ❑ PUBLIC WORKS DEPT. ❑ PROJECT: rUlr \4 G+�1J1 9 LOCATION: 53r »J ( S 44 7 . WAT The above mentioned applicant has submitted the following plans or materials for the -above reference project: vironmental Checklist ❑Preliminary Plat ❑ Environmental Impact State- ❑ Final Plat ment ❑Site /Development Plans ❑ Rezone Request- ❑ Shoreline Permit Application❑ Variance Request ❑ Conditional Use Permit ❑Other: Application The attached materials are sent to you for your review and comment. The Planning Dept. needs your comments to satisfy review procedures and to complete the project file. Please use the space provided below for your comments or attach a separate sheet. Requested response date: 1 / / 8Z Review Department comments: 9 (5) �� (.-) p67 /'r,r •19oa • City of Tukwila 6200 Southcenter Boulevard Tukwila Washington 98188 PLANNING DEPARTMENT TRANSMITTAL DATE OF TRANSMITTAL 4 / / 82 TO: ❑ BUILDING DEPT. ❑ FIRE DEPT. ❑ PUBLIC WORKS DEPT. OPOLICE DEPT. ❑ RECREATION DEPT. PROJECT: AMer VJOsitiN LOIJ22S LOCATION: The above mentioned applicant has'submitted the following plans or materials for the -above reference project: Environmental Checklist ❑Preliminary Plat DEnvironmental Impact State- ❑Final Plat ment ❑Site /Development Plans ❑Rezone Request- 0 Shoreline Permit Application❑ Variance Request ❑Conditional Use Permit ❑Other: Application The attached materials are sent to you for your review and comment. The Planning Dept. needs your comments to satisfy review procedures and to complete the project file. Please use the space provided below for your comments or attach a separate sheet. Requested response date: 4/ 17/SZ Review Department comments: s7,1.s,•. 5/11/82 POLICE DEPARTMENT'S RESPONSE TO PUGET WESTERN CONDO ENVIRONMENTAL CHECKLIST. We disagree with the developer's response to Question #13, Sections (c) & (d). It appears to us that the addition of an additional 108 living units in a rather small area will have a major impact on the existing transportation sys- tem in the area. Slade Way, 53rd Ave. So., & So. 160th Streets will probably have to be upgraded to handle the increased traffic. Access to and from this project will have to be carefully planned to avoid traffic accident problems since the driveways appear to be located in a hilly, curvy area where sight distances could create a problem. If entrances /exits are not carefully planned, there will be a substantially increased risk of traffic accidents which will cause people to seek alternate routes. We would also like to see at least one more point of ingress /egress, preferably near the middle of the complex. We also disagree with the answer provided to Question #14 (b). It is our opinion that the addition of 108 living units will definately have an im- pact on police protection. Traffic in the area will certainly increase causing an increased load on the traffic enforcement and accident investigation people. One hundred and eight additional living places in the City means an increased load on the department to provide routine patrol services as well as criminal investigations of incidents that will inevitably increase because of having buildings where none now exist. Residential property will increase the number of burglaries, auto thefts, domestic incidents and other crimes to which the department must respond and investigate. The problem is not in- surmountable but it will most assuredly have a negative affect on police pro- tection City wide unless police manpower allocations are increased. We would also like to request that the architect make contact with the Tukwila Police Crime Prevention Officer prior to final approval of landscaping and lighting plans so that we can make specific suggestions from a Crime Preven- tion viewpoint. City of Tukwila 6200 Southcenter Boulevard Tukwila Washington 98188 PLANNING DEPARTMENT TRANSMITTAL DATE OF TRANSMITTAL q' / 7 / S2 TO: ❑ BUILDING DEPT. ❑ POLICE DEPT. FIRE DEPT. ❑ RECREATION DEPT. ❑ PUBLIC WORKS DEPT. ❑ ? k r f Nwellw 6/ % A.N) vAT The above mentioned applicant has'submitted the following plans or materials for the -above reference project: Environmental Checklist ❑Preliminary Plat OEnvironmental Impact State- ❑Final Plat ment ❑Site /Development Plans ❑Rezone Request- 0 Shoreline Permit Application❑ Variance Request ['Conditional Use Permit ❑Other: Application The attached materials are sent to you for your review and comment. Planning Dept. needs your comments to satisfy review procedures and complete the project file. PROJECT: LOCATION: Please use the space provided below for your sheet. Requested response date: nReview Department comments: \� ) / _ , 5/5 ',1-- A7 -c ,J '- , J -c-e= r0e s ; ,1;.--,;v e 5 I 1 /M. / b et- doh/ I. „. • Z•a1 d. 5” .S e r .,j c `,.1 The to comments or attach a separate 7101" to •e)C c e e s o/ ✓ / i 7/'%;:s /1 -e A / 5 1 S17o Me V -To LS 1ewi 71/417 edeal. J,�wIL4 %� City of Tukwila 6200 Southcenter Boulevard �o Tukwila Washington 98188 _19oa PLANNING DEPARTMENT TRANSMITTAL DATE OF TRANSMITTAL 4 / 7 / 82 TO: ❑ BUILDING DEPT. ❑ POLICE DEPT. ❑ FIRE DEPT. ❑ RECREATION DEPT. UBLIC WORKS DEPT. PROJECT: N.ue,Ir4zp L cr) LOCATION: 5'0 AVF, 2 wAT The above mentioned applicant has submitted the following plans or materials for the above reference project: J�1 Environmental Checklist ❑Preliminary Plat / DEnvironmental Impact State- ❑ Final Plat ment ❑Site /Development Plans ❑Rezone Request - ❑ Shoreline Permit Application❑ Variance Request ❑Conditional Use Permit ❑Other: Application The attached materials are sent to you for your review and comment. The Planning Dept. needs your comments to satisfy review procedures and to complete the project file. Please use the space provided below for your comments or attach a separate sheet. Requested response date: 4 / 11 182 Review Department comments: OfFICE MEMO (� CITY of TUKWILA TO : pr201,1 els 941 L FROM: µp,1214 G. DATE: W /Awl 82 SUBJECT: FUG(' \tiEsm1zt.) COOP - SEM G +E.cr-.ISf TO t wth t,e. ( Nagy ON /our, 1 ►.IEEt, `(DU1C. StPth GOIAH WrS . Ask? :7 WERE- DoE oc) 5 -.I -7. 0. City. of Tukwila 6200 Southcenter Boulevard Tukwila Washington 98188 Frank Todd, Mayor M EMORANDUM TO: Brad.Collins, Planning Director FROM: Phillip R. Fraser, Senior. Engineer DATE: 5/17/82 SUBJECT: Public Works Department Review. of Valley View Estates /53rd Avenue South and Slade Way The Public Works Department has provided a preliminary review to determine the completeness of the subject site development per plan submittal A -1, C -1, C -2 and C-3 and the report GeoTechnical Design Consultation Proposed Condominium Development, Slade Way and 53rd Avenue South from Mithune Associates - submitted 5/3/82. Per this review a resubmittal of the report and plan documents is required of the developer to address the following deficiencies: 1. Report GeoTechnical Design Consultation Proposed Condominium Develop- ment, Slade Way and 53rd Avenue South a. The submitted Geotechnical Design Consultation Report is considered preliminary in nature and not a final soils report document. This particular site is adjacent to and /or the site itself has been in- volved in large earth slides in both the recent and-distant past. b. Because substantial drainage problems have existed with the site which may limit the type of developments which can be proposed, it is con - sidered appropriate (as stated in "further studies" portion of the report), that several borings and sub - surface investigations be carried out in a final soils report. A hydraulogical study and field investi- gation are considered necessary prior to final conclusions as to the number, type, size and location of the sitings of the building struct- ures and required utilities on -site and in the adjacent public right- of -way. Included in the hydraulogical analysis shall be a survey of the exist- ing 12 -inch City storm system traversing the property through easements. A determination shall be made as to the adequacy of the existing storm system to accomodate the proposed development. • Valley View Estates (Continued) Page 2 of 4 2. Hydrant /Fire Loop /Sprinkler and Domestic Service a. Plan C -3, outline specification #3 - violation of the Tukwila Munici- ple Code 14.04.060. Per A.P.W.A. Specification Requirement 95% com- paction shall be substituted for 90% stated compaction. Excavation trench material may be used as back -fill if it conforms to A.P.W.A.'s 73- 2.02A. b. Plan C -3 outline specification #6 - violation of Tukwila Municipal Code 14.04.060. Mechanical joints for water mains in Tukwila are not allowed. Non- restrained joints shall be rubber gasket, push -on type, (i.e., Tyton Joint). c. Plan C -3 outline specification #7 - violation of Tukwila Municipal Code 14.04.060. Number 7 states construction standards of Water District #75 should read construction standards of the City of Tukwila. d. Plan C -3 outline specification #9 - violation of Tukwila Municipal Code 14.24.030. Inadequate spacing and number of fire hydrants.. e. Plan C -3, outline specification #10 - violation of Tukwila Municipal Code 14.04.060. 1. The proposal is to connect to the main on the West Valley Highway is over one mile, as the crow flies, from the job site, is unreal- istic. 2. Proposed use of the Mueller H -610 tapping sleeve is for cast iron water mains in the 14 -inch to 48 -inch size only, therefore inappro- priate in terms of size for the water mains indicated on the pro- posed development. An H -610 also is a chaulked tapping sleeve which is not allowed. f. Plan C -3 outline specification violates Tukwila Municipal Code 14.04.060. This plan is deficient in number of gate valves required by the Public Works Department. g. Plan C -3 violates Tukwila Municipal Code 14.04.230 and Tukwila Municipal Code 14.04.250 (C) — location of the water meters and recorded easements or letter of intent to provide recorded easements shall be provided with final plan submittal for the purpose of allowing Public Works Department staff access to the water meters. h. Plan C -3 outline specifications - violation of Public Works Department Submittal Policy 05 -12, Item #1 which states, Water systems and exten- sions for both domestic, irrigation and fire service. Fire services shall be approved by insurance underwriters and the Tukwila Fire Depart- ment prior to submittal to the Public Works Department for review." The development of Slade Way to current City standards will include mains and hydrants. 1, • C Valley View Estates (Continued) Page 3 of 4 3. Sanitary Sewerate System a. Plan C -3 outline specification _ #2. - violation of City Ordinance #1250, per A.P.W.A. 1981 Edition, Division III, 61 -5, and Standard Plan #62, all rigid pipe shall be Class "B" bedding and all flexible pipe shall be Type "F" bedding. Tukwila design requirements, where questionable soils conditions and history of sliding have occurred, such as this site, the bedding requirements revert to those equal or better to "under paved areas ". b. The existing sewerage system for site development will connect into is the Val -Vue Sewer District. A letter from Val -Vue District offices as to their requirements is required to complete the plan submittal. At some in the future this sewerage system may be turned over to the City. Therefore, requirements of the Tukwila Municipal Code and the Public Works Department design requirements shall be met with the proposal. The Public Works. Department currently requires that no structures be placed over existing sewer lines or easements, (i.e., Buildings 3, 6, 7, 10.& 11). Those structures sited over existing Val -Vue sewer mains shall be relocated and /or the existing mains relocated as part of the proposal. c. Plan C -2 outline specifications and plans fail to call out a minimum 2% grade per Tukwila Municipal Code 14.12.150 for Sanitary Side Sewers. d. Plan C -3, proposed prefabrication sewerage life station: this submittal is deficient in the following submittals, 1) complete plan set of sewer- age lift station drawings, 2) hydraulic calculations, 3) pump curves, 4) letter from D.O.E. indicating that requirements for construction in- cluding storage and stand -by requirements have been met. Per the City of Tukwila's requirements the 4 -inch force main shall be ductile iron pipe, Class 52. 4. Curb Cuts /Access /Sidewalks - including public roadway improvements a. A traffic study to allow for this type of development outlining private and public improvements in Slade Way and 53rd, is required as part of a complete submittal. b. Plan C -1, C -2 and C -3, per Tukwila Municipal Code Chapter 11.64, Ordinani #1233, 1217 and 1158 - whenever building permit application is made for the construction of a multi - residential, commercial or industrial structures within the City, the party seeking such permits shall submit . a sidewalk construction plan for approval by the departments of Public Works and Planning. In lieu of such a plan submittal per Tukwila Muni- cipal Code 11.64.040 exceptions or waivers to this requirement may be granted by the City Council. As final grade and configuration of Slade Way is not known by Public Works, it is recommended that the developer agree to participate in a future L.I.D. to improve the roadway includ- ing sidewalks or improve the portion of the road fronting his property when the final grade and configuration is known. •i Valley View Estates (Continued) Page 4 of 4 5: Storm Drainage a. Accompanying-the plan documents shall be the hydraulic calculations and analysis including a survey .of.the existing City storm system relative to the::'feasibility for the site development. Included in this hydraulic report shall be the needed upgrading of the storm :system within the property and also to the public right -of -way in. Slade. Way and 53rd Avenue South. (The recent cave -in of over 100 feet of Slade Way adjacent to the property may require special considerations for the siting of structures and utilities.) er -.past practices, a violation of Tukwila design requirements - all;storm: pipe provided at over 20% grade (i.e., Building #2 - `46 %-grade and Buildings. #8,and #9 - 40% grade) shall be provided i th�ductile iron pipe and h • 1'an;:_C -1: outline specification #2 - violation of. Tukwila design -specifications for providing underground utilities and unsuitable ors prior slide areas : compaction shall - be 95% throughout. Per A: P. W.A...- 1981 Edition, Division III 61-5 and Standard Plan #62`all':rigid pipe shall be Class "B" bedding and all flexible -pipe-shall be .Type . " F" bedding. xc: PF:jst Byron G .- Sneva, Public Works Director Ted Freemire, Public Works Superintendent Dave Grage;.:.Water Department Crew Chief Ray Doll,'Sewer Department Crew Chief Ralph Trepanier, Street Department Crew Chief w "A 4, City of Tukwila • 6200 Southcenter Boulevard 2p Tukwila Washington 98188 • Frank Todd, Mayor 1908 TO: MARK CAUGHEY FROM: Don Williams DATE: May 17, 1982 SUBJECT: E.C.F. RESPONSE REGARDING PUGET WESTERN CONDOS. MEMORANDUM The E.C.F. contained a small plat map and, of course, the developer's responses to the various questions asked. This response is based on the limited information before me at this time. Question #19 asks if the project will have an impact upon the quality or quantity of existing recreational opportunities. The answer indicated is "no." I cannot agree and would add the developer must assume the 110 to 200 residents will seek recreation opportunities from within this community. The need for parks and recreation programs will certainly be sought by the new residents. With this need in mind, I have reviewed the developer's plans and see no "usable ". recreation facilities such as picnic areas, tennis courts, play courts, swimming pool or recreation building. I request the developer be encouraged to develop "usable" recreation facilities for the condo residents. Currently this part of the City has no developed park, but is served by the Tukwila Community Center's programs. If some nearby park land isdevel- , oped, it would satisfy most:of1;the, resident's needs, ,however, there .is, a strong potential that other such projects in this general area, when developed, will also place demands on the potential park. I will request that any such development in the McMicken community provide such "usable" space. The potential heavy use of the new park exists now with both the single family residential area and nearby commercial area presently seeking the development of the park. Residents who will live in developments such as Puget Western's will certainly add to the park's usage. I did recognize the 1.7 acres of green belt which will help separate and screen noise, light, glare, etc., however, it is not "usable" space from my point of view. MARK CAUGHEY May 17, 1982 Page 2 E.C.F. RESPONSE REGARDING PUGET WESTERN CONDOS. Also, on the north end of the project, we have Trail #9 on Seattle's large pipe - line:R /W. A possible trail connection exists from the development to the trail, however, approval would be needed from the Seattle Water Department. On the south end of the project, we would like to talk to the developer with regard to an easement for the development of a foot trail from Slade Way to Klickitat Drive. Presently this potential trail is part of our new park plan. I would like to discuss this idea with the developer at the ap- propriate_time. DW /co CITY OF TU KW I LA CT i" c.7 7unrt :LA, ENVIRONMENTAL CHECKLIST FORM MAY 3 1232 WILDING DEPT, This questionnaire must be completed and submitted with the application for permit. This questionnaire must be completed by all persons applying for a permit from the City of Tukwila, unless it is determined by the Responsible Official that the permit is exempt or unless the applicant and Responsible Ufficial previously agree an Environmental Impact Statement needs to be completed. A fee of $50.00 must accompany the filling of the Environmental Questionnaire to cover costs of the threshold determination. I. BACKGROUND 1. Name of Proponent: Mr. & Mrs. Herman M. Allenbach 2. Address and Phone Number of Proponent: c/o The Mithun Associates, P.S. 2000.112th Avenue NE, Bellevue, WA 98004 454 -3344 3. Date Checklist Submitted: May 3, 1982 4. Agency Requiring Checklist: City of Tukwila 5. Name of Proposal, if applicable: Valley View Estates 6. Nature and Brief Description of the Proposal (including but not limited to its size, general design elements, and other factors that will give an accurate understanding of its scope and nature): A condominium complex, geared to young professionals, consisting of 18 buildings of 6 units each. Units will step across the hill. Each building will be a maximum footprint of 36' wide x 63' long. Minimum distance between buildings shall be 20'. Materials will be a combination of stucco and horizontal cedar siding. Roofs will be composition. 7: Location of Proposal (describe the physical setting of the proposal, as well as the extent of the land area affected by any environmental im- pacts, including any other information needed to give an accurate under- standing of the environmental setting of the proposal): The site is located west of the I -5 corridor bounded by Slade Way to the south. The area affected is approximately 2.5 acres of R -4 zone and 2.9 acres of RMH zone. The R -1 zone of approximately 1.7 acres will remain intact as green belt. The site slopes from 8% to 36 %. Althou•h soils are of sound material the water runo , •o su•sur ace an sur ace, as cause • previous s i•es. green belt corridor varying from 45' wide to 225' wide will be maintained between the exis ing sing e ami y ousing o e wes an is •eve opmen End 1983 Estimated Date for Completion of the Proposal: 9. List of all Permits, Licenses or Government Approvals Required for the Proposal (federal, state and local): (a) Rezone, conditional use, shoreline permit, etc. YES !SOX (b) King County Hydraulics Permit YES X NO (c) Building permit YES NO (d) Puget Sound Air Pollution Control Permit YES NO x (e) Sewer hook up permit YES x NO (f) Sign permit YES x NO (g) Water hook up permit YES x NO (h) Storm water system permit YES x NO (i) Curb cut permit YES x NO (j) Electrical permit (State of Washington) YES x NO (k) Plumbing permit (King County) YES x NO (1) Other: 10. Do you have any plans for 'future additions, expansion, or futher activity related to or connected with this proposal? If yes, explain: No expansion to occur. 11. Do you know of any plans by others which may affect the property covered by your proposal? If yes, explain: —Ne— V MIL S < J t\ 07s7-- 1-wcvs - - 12.4c s (17/ °2 mew , 12. 'Attach any other application form that has been completed regarding the pro- posal; if none has been completed, but is expected to be filed at some future date, describe the nature of such application form: Application for building permit, also see above. II. ENVIRONMENTAL IMPACTS (Explanations of all "yes" and "maybe" answers are required) 1.. Earth. Will the proposal result in: (a) Unstable earth conditions or in changes in geologic substructures? (b) Disruptions, displacements, compaction or overcover- ing of the soil? (c) Change in topography or ground surface relief fea- tures? YES MAYBE NO (d) The destruction, covering or modification of any unique geologic or physical features? 1. EARTH Seven of the 18 proposed buildings are located in existing slopes in excess of 20% and reaching a maximum of 37 %. These re building • numbers 1, 2, 5, 6, 7, lO and 11. Of the s Oen buildings placed on these slopes, building numbers 2, 5, 6, 7 and 11 will have the grades adjacent to them adjusted. A11 arading work will be performed per soils engineers recommendationtO All work to be performed during normal business hours. Site contouring will dire water away from the building and will be controlled to eliminate erosion. -d 2) 3. WATER The addition of buildings to this site would create changes to 6. the water absorption rate as -well as changes to the drainage pattern. For this reason arrow (36' wide) buildings have been -0 designed to minimize hydro ulic problems. A storm detention system has been designed to cath'a•ll existing and new run -off before crossing the parking lot and driveway spline. 5. FAUNA GAlthough smaller buildings have been designed and it is the LA . intent of the proponent to phase construction with sales of units C the completed project would reduce the number of land animals and birds. (e) Any increase in wind or water erosion of soils, either on or off the site? (f) Changes in deposition or erosion of beach sands, or changes in siltation, deposition or erosion which may modify the channel of a river or stream or the . bed of the ocean or any bay, inlet or lake? Explanation:. 2. Air. Will the proposal result in: (a) Air emissions or deterioration of ambient air quality? (b)* The creation of'objectionable odors? (c) Alteration of air movement, moisture or temperature, or any change in climate, either locally or regionally? YES MAYBE NO x Explanation: For approximately three working days, asphalt paving will occur. Otherwise no odors will be emitted by occupants. 3. Water. Will the proposal result in: (a) Changes in currents, or the course or direction of water movements, in either marine or fresh waters? (b) Changes in absorption rates, drainage patterns, Dr the rate and amount of surface water runoff? _('c) -Alterations to the course or flow of flood waters? (d) Change in the amount of . surface water in any water body? (e) Discharge into surface waters, or in any alteration of surface water quality, including but not limited to temperature, dissolved oxygen or turbidity? (f) (g) Alteration of the direction or rate of flow of ground waters? • Change in the quantity of ground waters, either through direct additions or withdrawals, or through interception of an aquifer by cuts or excavations? x x x x (h) Deterioration in ground water quality, either through direct injection, or through the seepage of leachate, phosphates, detergents, waterborne virus or bacteria, or other substances into the ground waters? x Reduction in the amount of water otherwise avail- able for public water supplies? x Explanation: See attached. (i) YES MAYBE NO 4. Flora. Will the proposal result in: (a) Change in the diversity of species, or numbers of any species of flora (including trees, shrubs, grass, crops, microflora and aquatic plants)? (b) Reduction of the numbers of any unique, rare or . endangered species of flora? (c) Introduction of new species of flora into an area, or in a barrier to the normal replenishment of existing species? (d) Reduction in acreage of any agricultural crop? Explanation: The proponent will be adding landscaping to offset the selective removal of vegetation. 5. Fauna. Will the proposal result in: (a). Changes in the diversity of species, or numbers of any species of fauna (birds, land animals including reptiles, fish and shellfish, benthic organisms, insects or microfauna)? (b) Reduction of the numbers of any unique, rare or endangered species of fauna? (c) Introduction of new species of fauna into an area, or result in a barrier to the migration or movement of fauna? (d) Deterioration to existing fish or wildlife habitat? Explanation: See attached. x x x x x 6. Noise. Will the proposal increase existing noise levels? YES MAYBE NO Explanation: Automobiles will be brought on to the site (maximum .162 for th.i.s proj:ect).. 7. Light and Glare. Will the proposal produce new light or glare? -x Explanation: The parking lot will uAe non -glare lighting on 2Q' poles.. The low reflective glass have been set 45 to the street to maximize view and minimize reflectance. However, cars will be coming onto the site after dark, projecting light beams. 8. Land Use. Will the proposal result in the altera- tion of the present or planned land use of an area? Explanation: • x The planned use for this parcel of property is R -1 even though the parcel is adjacent to I -5 freeway and. is buffered from existing R -1 via +40' grade change and mature vegetation. 9. Natural Resources. Will the proposal result in: (a) Increase in the rate of use of any natural resources? (b) Depletion of any nonrenewable natural resource? x x Explanation: A. Electricity will be used for heating. B. Concrete, gypsum drywall, glass and roofing are non - replenishable materials. 10. Risk of Upset. Does the proposal involve a risk of an explosion or the release of hazardous substances (including, but not limited to, oil, pesticides, chemicals or radi- ation) in the event of an accident or upset conditions? Explanation: x • 11. Population. Will the proposal alter the location, distribution, density, or growth rate of the human population of an area? YES MAYBE NO x Explanation:. Although many of the units are one bedroom units geared for young professionals the growth rate will be affected. The addition of 108 units will alter the existing distribution of people as well as density. 12. Housing. Will the proposal affect existing housing, or create a demand for additional housing? Explanation: Transportation /Circula ion. Will the proposal result in: (a) Generation of additio al vehicular movement? (b) Effects on existing parking facilities, or demand for new parking? x (c) Impact upon existing transportation systems? x (d) ,Alterations to present patterns of circulation ..=, ) or movement of people and /or goods? x — (e) •Alterations to waterborne, rail or air traffic? x d (f) Increase in traffic hazards to motor vehicles, 121 p - 3 bicyclists or pedestrians? x _ Explanation: t have any cars on it. The increase in auto movement will increase ha The increase in cars will not affect existing transportation systems. It is expected that at peak hours 1/2 to 2/3 of all vehicles will be accessing onto public roads. X14. Public Services. Will the proposal have an effect upon, or result in a need for.new or altered governmental services in any of the following areas: (a) Fire protection? (b) Police protection? (c) Schools? (d) Parks or other recreational facilities? (e) Maintenance of public facilities, including roads? x x x x x • YES MAYBE NO (f) Other governmental services? x Explanation: $.11a.de_Road= s_plannedfor future improvements., Additional maintenance would be required. Buildings wiii- beTspri`nklered` for fire safety. A possible increase in police protection may be necessary., However each unit will be wired for alarm system. 15. Energy. Will the proposal result in: (a) Use of substantial amounts of fuel or energy? (b) Demand upon existing sources of energy, or require the development of new sources of - energy? Explanation: Puget Power indicates adequate power supply. 16. Utilities. Will the proposal result in a need for new systems, or alterations to the following utilities: (a) Power or natural gas? (b) Communications systems? (c) Water? (d) Sewer or septic tanks? (e) Storm water drainage? x x x (f) Solid waste and disposal? x Explanation: .Other than utility hook -ups, the only alterations will be the addition of a detention system. 17. Human Health. Will the proposal result in the crea- tion of any health hazard or potential health hazard (excluding mental health)? Explanation: x • • 18. Aesthetics. Will the proposal result in the obstruc- tion of any scenic vista or view open to the public, or will the proposal result in the creation of.an aesthetically of- fensive site open to public view? YES MAYBE NO Explanation: A subjective question. However the adjacent properties are above roof heights of this project. Site will be screened from west by existing mature vegetation. 19. Recreation. Will the proposal result in an impact upon the quality or quantity of exist - ing recreational opportunities? Explanation: 20.. Archeological /Histroical. Will the proposal result in an alteration of a signifi- cant archeological or his - torical site, structure, object or building? Explanation: CERTIFICATION BY APPLICANT: I, the undersigned, state that to the best of my knowledge the above information is true and complete. It is understood that the lead agency may withdraw any declaration of non - significance that it might issue in reliance upon this checklist should there be any willful misrepresentation or willful lack of full disclosure on my part. ✓li'i'G�rix/�T�'Y Ae--41:‘4" Signature and Titl e ��• / 6.• Date ' //e Aa4 -8- S-2-- 07- x x • RECEIVED CITY OF TUKWILA MA 1982 PUBLIC 16GOAKS DEPT. Rit ■ / ' �// // / / .ice i' / '\ / / • /� ' / / / / --- - / / / / i / 1 / . / I ' " // '/ / / // �'"' �\\ i ' i 1 / / // \ -i `\ ' \`� \ / ,/ ! - -- / (we. I'°% 4-Off!) 3? �T - ---�_� N ao enr rb`W 213.83' eflvva lS•�rsMS..ri' jPxIMU.14 cAM> i A•7bJ 'LEGAL DESCRIPTION; That portion of Lots 3, 4 and 5, Block 1, and that portion of / 'Lots 23, 24, 25 and 26, Block 2, McMicken Heights Division 81 Unrecorded, and that portion of vacated South 161st Street and 54th Ave. 8., lying East of 53rd Ave. South and North and East t of Slade Way, and Nest of the right of way of Interstate rreevay ( 95, situated in the Northwest Quarter of Section 26, Township Id. 23 North, Range 4 East, N.M., in Xing County, Washington; EXCEPT highway drainage line right of way lying within • strip of land having a width of 40 feet being 20 feet wide on each side when measured at right angles from the following described D) Line Survey, Begin on said N -Line Survey at Station N- 99 *60,.thence North 38.40' West 30.50 feet, thence North 62•l0" Neat 108.00 feat, to the True -Point of Beginning of this 03 Line description; thence South 51.06' Nest 159.10 feet, thence South 63.36' 80.50 feet, thence South 43.56'50" Nest 119.20 feet, thence South 16'66'30" Nest 67.0 feet, thence South.3•14'30• Nest 274.20 feet to a point and the and of this 03 Line description and begin at Station 03 3.58.6 on said D3 Line Survey, thence North 78'33'30' Nest 70 feet to • point, and the and of this line description. 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Sae,c7✓-'AL C.94, /J6-S FaK rie 7/rw/ NOTE : KLiLAI T.•. .z4 krraer R� Cc,A- Iµ1C1•61, Lncrcric.L_ M4rrX'.4 110.6 p 2mvn F sweet Q Axel; Fema Lj RECEIVED aTY OP TUXWN ► MAY 91982 WILDING OEM L_J Pen log E.° =y -> loot JOB NO ems, DATE: y•q -bz PUGET WESTERN, INC. Puget Power Building, Bellevue, WA 98009 (206) 454 -6363 Mr. Brad Collins Planning Director City of Tukwila 6200 Southcenter Blvd. Tukwila, WA. 98188. Reference: Valley View Estates May 4, 1982 VALL -1/82 -CAUS Attached per your request is a copy of the Earnest Money Agreement between Herman M. and Veloy S. Allenback and Jack and Helen A. Jamison. This agreement is for the purchase of Lot 7, Block 1 McMicken Heights Division #1, unrecorded, less the East 170' less State Highway. Also attached is a copy of the Agreement for Extension of Close of Escrow for your use. Should you have any questions concerning this matter feel free to call me at 451 -3027. ck Causey Manager Develop nt Planning Enclosures DC:cf WORKING DRAFT ENVIRONMENTAL IMPACT STATEMENT VALLEY VIEW ESTATES CITY OF TUKWILA PLANNING DEPARTMENT R.W. THORPE AND ASSOCIATES, INC. PFIELIMISUgJECT , '" �o REViSI DRAFT ENVIRONMENTAL IMPACT STATEMENT FOR VALLEY VIEW ESTATES PREPARED BY R.W. THORPE AND ASSOCIATES, INC. FOR CITY OF TUKWILA PLANNING DEPARTMENT TUKWILA, WASHINGTON Prepared in Compliance with The State Environmental Policy Act of 1971 Chapter 43.21c, Revised Code of Washington, as amended SEPA Guidelines, Effective January 16, 1976 Chapter 197 -10, Washington Administrative Code, as revised City of Tukwila Ordinance Number 1211 1984 0 F w J 0 1— cc 0 z TABLE OF CONTENTS Page # Introduction 1/1 Distribution List d I. Summary 1 A. The Proposed Action 1 B. Summary of Potential and Indirect Environmental Impacts C. Alternatives Sot. D. Summary of Mitigating Measures (� E. Unavoidable Adverse Impacts !S II. Description of the Proposal t A. Name of the Proposal 1'7 B. Project Sponsor l7 C. Project Location 17 D. File Numbers of other Agencies involved NA E. Site Description 17 F. Description of the Surrounding, Area L 7 G. Major Physical and Engineering Aspects of the Proposal 1-7 H. Relationship to Existing Laws, Plans and Policies.. 1$ III. Existing Conditions, Impacts and Mitigating Measures.... zl A. Index of Elements of the Environment ZI B. Elements of the Physical Environment Z4- C. Elements of the Human Enviroment Sb IV. Unavoidable Adverse Impacts q 3 V. Short Term Use vs. Long Term Productivity 4`f VI. Irreversible and Irretrievable Commitment of Resources`fig VII. Alternatives to the Proposal 9E7 VIII.Appendices A. Zoning Regulations B. Noise Impact Analysis C. Geo- technical and Hydrological Studies D. Letters from Fire and Police Departments E. Traffic Study LIST OF FIGURES AND TABLES FIGURES TABLES INTRODUCTION Name of Proposal Valley View Estates Pro sect Sponsor Dr. Herman Allenbach 1018 SW 144th Seattle, WA 98166 Nature of Proposal Construction of an eighteen building development containing 108 -unit condominiums on a 7.08 acre site. The condominiums would be clustered with 6 units per building. Project development will require a service area agreement or deannexation from Water District #75 in order to tie into the City of Tukwila pressure reducing station. Project Location The 7.08 acre site is located in Tukwila, lying east of 53rd Avenue South; south, north, and east of Slade Avenue, and west'of the R.O.W. of Inter- state 5. The undeveloped site is located on the hillside above the freeway overlooking the Green River Valley. Lead Agency City of Tukwila Planning Department Responsible Official Brad Collins, Planning Director Planning Department City of Tukwila Contact Person Brad Collins, Planning Dir. City of Tukwila Planning Dept. City Hall 6200 Southcenter Boulevard Tukwila, WA 98188 (206) 433 -1849 Authors and Principal Contributors This EIS was prepared under the direction of the City of Tukwila Planning Department. Research and analysis were provided by the following firms: R.W. Thorpe and Associates i 815 Seattle Tower 3rd and ,University 4 Seattle,; k ' 98101 (206) 624 -6239 Contact: Robert W. Thorpe, AICP; Project Manager, Jon Potter Stepan and Associates 930 South 336th Street - Suite A Federal Way, WA 98003 Contact: Glen McKinney (206) 682 -4771 Mithun and Associates 2000 112th Ave NE Bellevue, WA Contact: Vince Ferese, A.I.A. (206) 454 -3344 The TRANSPO Group 23 -148th Ave SE Bellevue, WA 98007 Contact: Kurt Gahnberg (206) 641 -3881 Town, Richards, and Chaudier 105 NE 56th Seattle, WA Contact: Jan Hauge (206) 523 -3350 Geo Engineers 2020 124th NE Bellevue, WA Contact: Jack Tuttle (206) 881 -7900 iv Actions; Permits; and Licenses Required Building Permits Engineering Plan Approvals Site Plan Approval Board of Architectural Review City Hydraulics Permit Electrical Permits Occupancy Permit All other permits necessary to construct buildings and improvements proposed on the site. Location of EIS Background Data R.W. Thorpe and Associates 815 Seattle Tower 3rd and University Seattle, WA 98101 Tukwila Planning Department City of Tukwila City Hall 6200 Southcenter Boulevard Tukwila, WA 98188 Bate of Issue of Draft EIS June , 1984 Date Responses on Draft EIS Must be Received by. the Lead Agency , 1984 Cost of Document: Mail Comments to: All comments on this Draft EIS should be addressed to: Brad Collins, Planning Director City of Tukwila Planning Department (at the above address) V DISTRIBUTION LIST Federal Agencies Environmental Evaluation Branch EPA Attn: Ms. Lisa Corbyn Director 1200 6th Avenue MS 443 Seattle, WA 98101 Environmental Protection Agency Attn: Mr. Walt Jaspers Director of Federal Affairs 1200 6th Avenue MS 623 Seattle, WA 98101 Office of Community Planning & Development Attn: Mr. Charles Bickley, Director Dept of Housing and Urban Development Arcade Plaza Building MS 427 Seattle, WA 98101 Department of Energy Attn: Ms. Nan Evans, Room 1992, Federal Building 915 Second Avenue Seattle, WA 98104 U.S. Army Corps of Engineers Attn: Col. Leon Moraski Seattle District NPSEN -PL -RP PO Box C -3755 Seattle, WA 98124 State Agencies Environmental Review Section Attn: Ms. Debbie Kneeland Department of Ecology, MS PV -11 Olympia, WA 98504 Washington State Dept of Game Habitat Management Division Attn: Mr. Bob Zeigler 600 North Capitol Way Olympia, WA 98504 Washington State Dept of Natural Resources Attn: Mr. Harry Anderson Public Land Building MS ER -11 Olympia, WA 98504 Washington State Dept of Ecology Attn: Mr. Stan Springer, Head Environmental Review St. Martin's College Campus Lacey, WA 98504 Washington State Dept of Transportation vi Washington State Dept of Transportation Attn: Mr. Bernie Chaplin Environmental Planner Highway Administration Bldg MS KF -01 Olympia, WA 98504 Washington State Historic Preservation Office Attn: Ms. Jeanne M. Welch, Director 111 W. 21st Ave. MS KL -11 Olympia, WA 98504 Office of Public Archaeology University of Washington Attn: Mr. Jerry Jermann, Director 213 Engineering Annex, FM -12 Seattle, WA 98195 Regional Agencies Dept of Transportation Attn: Mr. Jerry Zirkle District Engineer, District #1 6431 Corson Ave S Seattle, WA 98108 Environmental Planning Division Attn: Rodney G. Proctor, Manager Metro, MS 63 821 Second Avenue Seattle, WA 98104 Metro - Sewerage 1200 Monster Road SW Renton, WA 98055 Metro - Transit 821 Second Seattle, WA 98101 Puget Sound Air Pollution Control Agency Attn: Mr. A.R. Dammkoehler, Air Pollution Control Officer PO Box 9863 Seattle, WA 98109 Puget Sound Council of Governments Attn: Ms. Barbara Hastings 216 First Avenue S Seattle, WA 98104 Seattle/King County Commuter Pool Program Attn: Mr. William T. Roach, Program Manager Arctic Building, Room 600 704 Third Avenue Seattle, WA 98104 Bob Grieve Ring County Council 4th Floor /King County Courthouse Seattle, WA 98104 Local Agencies Ring County Dept of Public Works Surface Water Management Attn: Mr. George Wannamaker, Director 969 Ring County Adminstration Building Seattle, WA 98104 Ring County Dept of Budget & Program Development EIS Review Attn: Mr. Bob Edmundson 400 Ring County Courhouse Seattle, WA 98104 Ring County Drainage District #1 Attn: Mr. Jack Nelson 25403 104th Ave SE #3 Rent, WA 98031 Ring County Dept of Community Development Building and Land Development 410 Ring County Administration Building Seattle, WA 98104 King County Dept of Planning & Community Development Planning Division Attn: Ms. Karen Rahm, Manager W217 Ring County Courthouse Seattle, WA 98104 Ring County Soil and Water Conservation Service 35 S. Grady Way Renton, WA 98055 Renton Planning Department Attn: Mr. Dave Clemens, Acting Director 200 Mill Street Renton, WA 98055 Seattle Water Department 821 2nd Avenue Seattle, WA 98104 Val -Vue Sewer District P.O. Box 68063 Seattle, WA 98168 Ring County Water District No. 75 P.O. Box 68100 Seattle, WA 98168 City of Tukwi +a Mayor City Council (7 copies) Planning Commission (9 copies) Public Works Department Parks and Recreation Department Police Department Fire Department City Attorney SEPA Information Center Ut ilia iesl-Services South Central School District #406 9690 South 144th Seattle, WA 98168 Puget Sound Power and Light Attn: Mr. Dick Causey Puget Power Building Bellevue, WA 98009 Washington Natural Gas Company 815 Mercer Seattle, WA 98109 Pacific Northwest Bell 107 N. Division Auburn, WA 98002 Newspapers Kent News Journal Attn: EIS Review PO Box 130 Kent, WA 98031 Highline Times PO Box 518 Seattle, WA 98166 Renton Record Chronicle Attn: Real Estate /Urban Affairs 801 Houser Way South Renton, WA 98055 Seattle Times Fairview & John Seattle, WA 98121 Seattle Post - Intelligencer 6th & Wall Seattle, WA 98121 Daily Journal of Commerce 83 Columbia Seattle, WA 98104 IX Private Organizations and Others Washington Environmental Council 107 S. Main Seattle, LWA 98104 Greater Tukwila Chamber of Commerce 950 Andover Park E Tukwila, WA 98188 Green River Study Group Attn: Ms. Carol Stoner PO Box 772 Kent, WA 98031 Rainier Audubon Society Conservation Committee Attn: Mr. Keith Bechard PO Box 778 Auburn, WA 98002 Neighborhood Residents Mr. Alfred Schmid 1525 Taylor Ave N #101 Seattle, WA 98109 Puget Western, Inc. Puget Power Building Bellevue, WA 98004 Bel Crest Realty, Inc.. 12431 Kingsgate Way NE Kirkland, WA 98033 Mr. Robert C. Christensen 16241 54th Ave S Seattle, WA 98188 Mr. Heinz Ritter 5213 S 164th Seattle, WA 98188 Mr. Jack R. Nyholm 5215 S 164th Seattle, WA 98188 Mr. Patrick Mitchell 16227 54th Ave S Seattle, WA 98188 Mr. Thomas C. Johanson 16231 54th Ave S Seattle, WA 98188 Ms.. Ruby A. Mitchell Mr. John D. Mitchell PO Box 68015 Seattle, WA 98188 Mr.. Gerard A Mcelholm 5156 S 160th St Seattle, WA 98188 Mr. Gordon M. Solem 5155 S 160th Seattle, WA 98188 M.D. Shawley 15811 53rd S Seattle, WA 98168 J.L. Barnes 15814 51st Ave S Seattle, WA 98188 Mr.. and. Mrs. W.. Lester Warehine 12016 26th Ave S Seattle, WA 98188 McNamara Investment Co., Inc. 1600 Dexter Ave N Suite #1 Seattle, WA 98109 Mr. John Y. Back 4439 S 170th Seattle, WA 98188 Mr. Raymond Nielson 5108 S 163rd P1 Seattle, WA 98188 Mr. Calvin M. Johnson 5110 S. 163rd P1 Seattle, WA 98188 Mr. Richard A. Goe 5112 S. 163rd P1 Seattle, WA 98188 Mr. Steven Welsh 5113 S. 163rd P1 Seattle, WA 98188 Mr. Robert T. Amundson 5111 S. 163rd P1 Seattle, WA 98188 Mr. David E. Yankee 5109 S. 163rd PL Seattle, WA 98188 Mr. James F. Rial 16243 52nd Ave .S Seattle, WA 98188 Mr. John E Schwarzmann 16251 52nd Ave S Seattle, WA 98188 R.H. Small 16244 52nd Ave S Seattle, WA 98188 Mr. Herbert W. Phalan 16250 52nd Ave S Seattle, WA 98188 Mr. Edgar D. Bauch 16603 53rd S. Seattle, WA 98188 Mr. Robert L. Crain 5105 S. 163rd P1 Seattle, WA 98188 Mr. Hans B West 5212 S. 164th Seattle, Wa. 98188 Mr. and Mrs. Richard McLester 5118 S 164th Tukwila, Wa. 98188 Mr. and Mrs. Leo Sowinski 16050 51st Ave S. Tukwila, Wa. 98188 Mr. and Mrs. Dennis Robinson 16038 48th Ave S. Seattle, Wa. 98188 John Barnes 15828 51st Ave S. Tukwila, Wa. 98188 Bearnie Onorati 5102 S. 163rd P1. Tukwila, Wa. 98188 Mrs. Ethel Mae Cole 16030 51st Ave S. Tukwila, Wa. 98188 Xi Al Pieper 17083 53rd Ave S. Tukwila, Wa. 98188 I. SUMMARY A. The Proposed Action The project sponsors propose to develop a 7.08 acre parcel with a 108 unit condominium. The development would be clustered with 18 - 6 plexes located along the east side of the property. The proposed buildings would occupy approximately 29 percent of the site. Based on the City's 1.5 parking stalls per dwelling unit requirement, 162 parking stalls would be provided on site. The buildings are designed to stairstep up the sloped site. Approximately 32 percent of the site would remain in its natural state. Two accesses would be provided from 53rd Avenue South and Slade Way. B. Summary of Potential Direct and Indirect Environmental Impacts 1 • Physical Environment Earth o Potentially unstable soils on slopes in excess of 40 percent in dry conditions and 20 percent in wet conditions. o Potential erosion during grading. o Alteration of topograhy to minimize potential development. Air o Short term generation of particulates during construction. o Short term generation of noxious odors from diesel powered vehicles and from asphalt paving during construction. o Slight increase in motor vehicle generated pollutants. o Significant increase in violation of Washington State Standards for levels of hydrocarbons. Water o Increased level of pollutants typical of residential developments in surface and ground water. o Reduction in ground water recharge. o Increased volume of storm water runoff from the site. Flora. o Removal of approximately 68 percent of the natural vegetation from the site. Fauna o Loss of approximately 68 percent of the natural habitat from the site with a corresponding loss of wildlife. Noise o Noise levels will increase during construction with frequent noise peaks, depending on the type of equipment used. o Negligible increase in traffic noise with the additional traffic generated. Light and Glare o Increased in low level lights at night due to parking and building lights. Land Use o The proposed action would preclude alternative land uses for the site during the life of the project. o Changes in the land use of the site from an undeveloped wooded site to condominium development. Natural Resources o Consumption of some natural resources for the construction of the project. Z 2. Human Environment Population o Increase in population by approximately 212 residents. Housing o Increase in housing stocks by 108 dwelling units. Transportation /Circulation o Vehicular traffic would increase by approximately 900 daily vehicle trips and 9 evening peak hour vehicle trips. Local streets and intersections would not experience a significant decrease in the level of service. o Potential of overflow parking onto the street during a few days of the year during possible social activities. o Insignificant increase in the potential of vehicular accidents in the vicinity. Fire o The proposed condominium project represents an increase in the fire service demand. Police o The proposed development would not necessitate the need for additional personnel but may be reflected in slightly increased response times throughout the City. Schools o Slight increase in demand for an additional classroom or portable classroom at Tyee High School. Parks and Recreation o Slight increase in demand for a neighborhood park. 3 Maintenance o A slight increase demand of city of Tukwila to maintain roadways and water system in the vicinity of the site. Slight increase in demand of Val Vue Sewer District to maintain sewer lines in vicinity of site. Energy o The proposed development would increase the consumption of electricity and petroleum products during construction and upon occupancy. Communication o Demand for a cable unit capable of carrying 216 lines to the site. Water o Extension of water lines to the site and dedicated to the city. Easements along the private road would be granted for access to maintain the system. o Possible brief interruption of water service to the vicinity during connection of the system. o Service area agreement or deannexation from Water District #75 in order to tie into City of Tukwila pressure reducing station. Sewer o Increased of up to 0.06 mgd to the Renton Treatment Plant. Stormwater o Increased volume of stormwater runoff. o Urban pollutant levels will increase in stormwater runoff. Solid. Waste o Increased demand for solid waste collection. Aesthetics o The existing wooded hillside would be converted to a condominium development featuring 18 -6 plexes covering approximately 29 percent of the site, parking lot, recreation area, and landscaped area covering approximately 39 percent of the site and; retention of approximately 32 percent of the natural vegetative landscape. Human Health o Short term annoyance and irritation to area residents during construction. Archaeological /Historical. o Remote possibility of uncovering archaeological resource. C• ALTERNATIVES TO THE PROPOSAL 1. No Development: Description The site would remain in its undeveloped state and continue to serve as a part of the wooded hillside. Impact All adverse environmental impacts of the project would be eliminated. Feasibility The proponent desires to construct a multiple family development, which would not be met by this alternative. Although the site is currently undeveloped, it is highly improbable the site would remain undeveloped unless it is acquired by the City of Tukwila or King County for park use or greenbelt. It is not shown as a park or greenbelt in the Comprehensive Plan nor designated for acquisition in the City's Capital Improvement Program. 2. Development to Single Family: Description Up to 21 detached dwelling units could be constructed under this zone. Impacts Overall, implementation of the single family density alternative would impact all elements of both the physical and human environments to a lesser degree than the proposed action. Traffic generation would be approximately 23 percent of the proposed action. Residential population would also be only 20 percent of that of the proposal. Feasibility Construction of a lower density single family alternative would not meet the objectives of the proponent of providing a multiple family residential development. Further, the necessary site improvements would in all probability, price the single family homes higher than their market value. 3. Development of More Intensive Us -e: Description Under the R -4 District - Low Apartments and RMH District - Multiple Residence High Density, the following uses are permitted: R -4 District: Apartment houses, row houses, boarding houses, childrens boarding homes, lodging houses, clinics for people only, convalescent homes, nursing homes, convents, private clubs or fraternal orders, schools other than those permitted in the R -2 District. RMH District: Any use permitted in the RMH District, Apartment House, hotels; offices and clinics provided they do not exceed the first two stories. Based on the listed permitted uses, a development scenario could include the following: Density Use Besiftnation Acres Yield Convalescent Home 2.52 @ 300 SF /patient 350 patients or lot area or Apartment Building 2.52 @ 30 DU /Ac. 75 DU's. and and Office (2 story) 2.86 @ 40% Site Coverage 50,000 s.f. Impacts Overall, implementation of this alternative would impact both the physical and human environments to a greater degree than that of the proposed action. Open space would be significantly reduced. Traffic generation would be roughly double that of the proposal. Feasibility This scenario would not meet the proponent's objective. Lower Density Multiple Family Development Description: Five fewer buildings would be constructed providing a total of 13 buildings with a total of 78 dwelling units. Impact Adverse environmental impacts would be less than those created by the proposed action. The parking lot would proportionately be reduced. Traffic generation would be reduced by approximately 28 percent. The site could support slightly more than one —half acre more of undeveloped open space than under the proposed action. Feasibility Construction of a lower density multiple family development would not meet the proponent's objective. Due to higher site improvement costs and infrastructure cost per dwelling unit compared to the proposed action, condominium prices would be higher than the proposed action and in all probability, price them higher than their market value. 5G D. Summary of Mitigating Measures Note: When the Draft EIS states that mitigating measures "will" be under- taken, it indicates that such measures are already planned as part of the proposal or that the Action Sponsor will provide them. Use of other language (such as "could" or "should ") indicates that the City, in its discretion, and in conformance with SEPA policies, will consider these mitigating measures as possible conditions in association with the issuance of the building permit. All recommendations contained within the geotechnical report will be complied with by the project sponsor, including the following summarized below: Earth: o The existing deep drainage facilities on State Highway right -of- way shall continue to be monitored by the State of Washington and maintained to prevent deterioration. o Slope movement shall be monitored through an instrumentation program which is to be maintained through to the construction phase and beyond. o Site grading shall be undertaken during the late summer - early fall months when the least amounts of rainfall can be expected and surface runoff and seepage from springs should be somewhat diminished. o All cuts steeper than 3:1 horizontal to vertical (33 percent) shall be supported by retaining structures constructed and backfilled per specifications of the geotechnical report. o Building foundations and drains shall be constructed per specifications of the geotechnical report. 6 o City of Tukwila requirements for grading and excavation will be followed to avoid erosion. o Plastic sheets and mulch should be used on portions of the ex- posed soil areas during construction to minimize erosion. o Landscaping shall be installed as soon as possible subsequent to completion of construction and should include plants suitable for the stabilization of the surface of steep slopes. o See related Mitigating Measures listed under "Geology and Soils ", page -, and "Surface Water Movement, Quantity, Quality, Runoff /Absorption ", page - -- o Collection of seepage and springs will be done during construction to minimize surface flow that could cause erosion. o Clearing and foundation constructon for buildings shall be done alternately in order to reduce erosion impacts. Air: o Low- emission construction equipment could be used whenever feasible. o Measures to control construction dust such as: watering, cleaning and sweeping of streets at the end of hauling activities could be performed by the contractor. o Unnecessary motor vehicle engine idling during construction could be eliminated; engines csIALLii.be shut off except when moving vehicles. Water: o A stormwater detention system for a 10 year storm capable of detaining 2,500 cubic feet of water is proposed to be installed. Stormwater will be stored in underground storage pipes for a 10 year storm. The proposed stormwater collection and detention 7 from runoff by controlling the rate of release to that which occurs under existing conditions. The length of time over which peak discharge would occur would be prolonged. All required temporary sedimentation and control facilities 274uld be constructed and in operation prior to paving and building con- struction. The City of Tukwila must approve stormwater drainage plans prior to issuance of the building permit. o Catch basins and oil /water separators are proposed within the on- site drainage collection system to separate sediments and petroleum residues from stormwater. On -site detention and the outlet control structure would further allow for separation of these pollutants from stormwater before release from the site. o Permanent French drains should be installed along the upslope sides of all parking areas, and along the east side of the condominium units. o Foundation drains should be installed and connected to drain lines along the east property line so the flow can be disposed of off the site. o A temporary storm management and erosion control measures will be employed during construction. Where possible, natural vegetation for silt control shall be maintained. Proposed interim drainage control measures include placing strawbales in drainage ditches and directing runoff to two interim detention ponds. o All temporary siltation ponds shall be maintained in a satisfactory condition until such time as cleaning and /or con- struction is completed and permanent drainage facilities are operational. 8 o Prior to site clearing, an interceptor trench should be installed at the toe of the roadway fill along the western boundary of the site. o Temporary drainage swale should be installed to collect runoff immediately following'site clearing and grubbing. o A portion of the existing perforated deep storm system will be abandoned and replaced by a new storm line to handle off -site runoff. The existing storm line that is above ground and leaking will be repaired. o The proponent xould have maintenance responsibility for the drainage control facilities during construction, and it is proposed that the City assume maintenance responsibility for these facilities after completion of the development. Catch basins and oil /water separators should be cleaned frequently and properly maintained to assure maximum attainable pollution separation. o Cleaning of streets and parking areas shall be undertaken whenever necessary during construction. o See related Mitigating Measures listed under "Geology and Soils ", page - - -, and "Erosion ", page - -- Flora: o Ornamental vegetation shall include sycamore along Slade Way and along the parking lot. Vine, maple and flowering cherry would be interspersed among the buildings. Other plant materials would include platinia, rhododendron, mahonia, vibrurnum Davidi, ivy and lawn. o The southwestern portion of the site,NgyjA,remain in its natural state. Disturbed areas not proposed to be landscaped would be seeded with clover and rye. Area which would remain in its undisturbed state amounts to approximately 2.3 acres. 9 o Approximately 2.3 acres or 32 percent of the site will remain in its natural state. Noise: o Double wall construction and 1/2 inch gypsum wall boards shall be utilized. o Insulation shall include R -11 fiberglass o Double glazed aluminum windows shall be included. o An exterior -to- interior attenuation of 30 dBA, about 5 dBA better than conventional construction, would provide generally acceptable interior noise levels according to the criteria cited. The additional 5 dBA attenuation can be achieved by using windows and glass doors having at least 5 dB better acoustical performance than conventional thermal insulated windows, as measured using sound transmission class (STC) rating or sound transmission loss curves. The windows and glass doors should, have a minimum overall outside -to- inside thickness of 1 ", which can be achieved by using either double or triple glazing, since the middle glazing of a triple glazed window does not contribute significantly to acoustical performance. Each glazing should have a minimum thickness of 3/16 ", and the outside and inside glazings should have different thicknesses in order to avoid acoustic coupling. For example, a window can consist of 1/4" glass, 9/16" air space, and 3/16" glass. The glass should be set in resilient gaskets. Operable windows and exterior doors (including glass doors) should be hinged rather than sliding, and should have resilient seals. Exterior doors should have automatic threshold drops or compressible neoprene threshold seals. These measures apply to north, south, and east facing windows and exterior doors. o East facing decks can be glass - enclosed, to effectively provide double windows between the outside and inside of the residential unit. If this construction is used, the 1" thickness is not necessary for the exterior or interior windows of the deck area. I0 o Forced -air ventilation could be provided, especially to bedrooms, so that windows would not have to be opened for ventilation. Open windows provide only about 10 to 15 dBA outside -to- inside noise attenuation. o Noise levels could be reduced for some exterior spaces by use of barriers. For example, an eight foot high solid continuous fence around the eastern half of the proposed children's area would reduce the average noise levels by about 10 dBA, to about 55 dBA or less, which is an acceptable level for preventing noise - induced speech interference and annoyance outdoors. The barriers would have the disadvantage of reducing views from this area. However, noise levels on the outdoor decks Sgald_bs reduced by about 5 dBA by using a solid barrier around the deck. The barrier should be high enough to block views of the freeway from a typical user location (presumably seated), but need not be so .high that it blocks views of the valley and mountains to the east. Acoustic barriers may be constructed of wood with minimum thickness of 3/4 inch. Plywood, board - and - batten, or tongue -and- groove construction are acoustically acceptable. Barriers should have no gaps or openings, including the base. Construction should not occur before 7 a.m. on weekdays and 9 a.m. on weekends, or after 10 p.m., to prevent State noise code violations. In addition, any diesel or gasoline powered equipment used at the site could be required to have a proper muffler that is in good condition. Light and Glare: o Perimeter landscaping will reduce light spillage. o Parking lot lighting could be directed so that no direct light spills off the site. o Light fixtures have been selected which walsCULlimit light spillage to 20 feet in height. 11 Land Use: o The proposed development of 18 6- plexes would occur adjacent to the 405/I -5 interchange in a predominately single family and undeveloped area of the Tukwila Planning Area. Commercial land uses exist across 405 and 1-5 from the project. Please refer to the Existing Land Use Map, page xx of this DEIS. Project development would add 108 dwelling units representing a 5.3 percent increase in the City's housing stock. The proposed density would be 15.25 dwelling units per acre. Transportation /Circulation o A left -turn lane for westbound -to- southbound left turns from Klickitat Drive to 53rd Avenue South would be desirable to eliminate conflicts between left- turning traffic and westbound thru traffic. Traffic accidents over the last three years shows a consistent pattern of rear -end accidents at this location which would be addressed and reduced significantly by such an improvement. This improvement would be considered desirable to improve existing intersection operation as well as in the future with and without the project. Project generated traffic will add about 2 percent additional traffic on this intersection and during peak hour it will increase the left turn of this approach volume about 25 percent. o Assure that project driveway locations are at least 150 feet away from the nearest intersection. The most current site plan available indicates that this condition is met by the current design. o Provide on -site parking overflow areas to accommodate frequent parking demand conditions in excess of 1.5 per dwelling unit. There appear to be capacity for about 20 vehicles in the area designated RMH in the Western portion of the site adjacent to 53rd Avenue. o Do not allow parking spaces on -site to be reserved for any particular residential unit. This will allow flexibility to accommodate fluctuating demand in the primary designated parking areas. IZ o Parking of recreational vehicles or trailers should be accommodated off -site to ensure the residential and visitor parking flexibility is maintained. o Work with Metro Transit to ensure a safe, convenient bus stop location for project transit patrons adjacent to the Valley View Estates site. Public Services: o A close working relationship between the developers and the Police department's Crime Prevention Officer should be maintained throughout the planning and building phases of this project. With the Crime Prevention Officer's assistance, crime and personal safety risks can be held at a minimum. o Adequate parking on site should provided to minimize the need for street parking - a source of vehicle accidents, pedestrian accidents, auto thefts and car prowl accidents. o Total recreation area provided on site will be 23,400 square feet, 1800 square feet more than required. o A 6,175 square foot children's play area is proposed which would include an open play area, sandbox, and other play equipment. o All requirements under Section 18.60.200, "Recreation Space in Multiple Family Districts" will be complied with. o Cover the trucks carrying excavation loads with canvas or tarp. o The developer could provide regular street cleaning during construction. Energy: o Insulated walls, floors, roof and glass could bq used through the structures. o An energy analysis of building design elements could bq undertaken to assess the feasibility of reducing long -term demand, e.g. passive solar energy systems. 13 Utilities: o All telephone lines shall be installed underground. o Installation of telephone lines shall be coordinated with installation of electrical lines. o Existing vegetation will be maintained along the western portion of the site. o Ornamental vegetation shall include Sycamore, along Slade Way and along the parking lot. Vine, maple and flowering cherry would be interspersed among the buildings. Other plant materials would include photinia, rhododendron, mahonia, vibrurnum Davidi, ivy and lawn. Historical /Archaeological: o In the event that cultural materials are disclosed during construction, work in the immediate area w°ul_ be discontinued and the Office of Archaeology and Historic Preservation would be notified. 14 E. Unavoidable Adverse~ Impacts Alteration of topography in order to minimize potential slope movement. o Short term odors during construction. o Removal of all natural vegetation from approximately 68 percent of the site. o Removal of vegetation will result in the loss of animal habitat. Most species that currently utilize the area proposed for grading and development will be eliminated. Urban tolerant species will replace those species which are not. o The project. would,, result in moderate unavoidable noise impacts to residents of the development because of the freeway noise which exists at the site. Construction activities would cause temporary noise impacts at the closest adjoining residences. o Consumption of building materials and energy. Potential spillover onto 53rd Avenue South, Rlickitat Drive or Slade Way due to possible social activity. o Traffic accidents may be expected to increase in some proportion to the increase in traffic volumes on streets surrounding the proposed development. o Increased demand for fire service. o Increased demand for police service. 15 o Increased demand for neighborhood park area in the Crestview neigborhood by approximately nine percent. o Increased demand for long -term city maintenance. o Increased energy demand on the site in both the short and long - terms. o Short -term impacts on vehicular travel at South 158th Street /53rd Avenue South if trendin: is required within the R.O.W. or across the road. o Sewage generated by the development would contribute to above capacity discharges at the Renton Metro Sewage Treatment Plant. o Short -term annoyance and irritation to area residents during construction. II. DESCRIPTION OF THE PROPOSAL A. Name of the Proposal: Valley View Estates B. Project Sponsor: Dr. H. M. Allenbach C. Project Location: The 7.08 acre site is generally located southwest of the Interstate 5 and Interstate 405 intersection in the City of Tukwila. Specifically, it is located east and north of Slade Way and west of 1-5. D. City of Tukwila File Number: i L," 2,05 - 63 • E. Site Description: The site is on an undeveloped hillside above the freeway overlooking Green River Valley. The property is heavily vegetated with small caliper alder with dense blackberry and some horsetails. F. The vicinity of the site is largely undeveloped and wooded. Single family homes are located west and south west of the site. The Interstate 5 corridor is east of the site. Please refer to aerial photo page f this DEIS. G. Major Physical and Engineering Aspects of the Proposal: The project sponsors propose to construct a 108 unit clustered condominium development. The development would contain 18 6- plexes. Each of the eighteen buildings would have two - two bedroom townhouses, two - one bedroom flats and, two - one bedroom townhouses. The buildings would be located along the eastern half of the property along the eastern half of the property on the down slope. 108 parking stalls would be provided between the buildings and Slade Way. Two 17 access points would be provided at either end of the site on Slade Way. Exterior treatment would be stained wood siding and stucco with Cedar trim composition shingles are also proposed. Planting would include sycamore along Slade Way and the parking lot. Vine, maple, and flowering cherry would be interspersed among the buildings. Other plant materials would include platinia, rhododendron, mahonia, vibrurnum Davidi, ivy and lawn. Areas which would remain in its undisturbed state amounts to approximately 2.3 acres. H. Relationship to Existing Lawsi Policies; and Plans 1. City of Tukwila Comprehensive Policy Plan The City of Tukwila Comprehensive Land Use Plan Map shows the site suitable for Low Density Residential. These areas' are characterized by single family residential uses; 0 -5 units per gross acre. A portion of the site is also shown as having special development considerations, due primarily to steep slopes and nearby springs. The Environmental Base Map, although general in nature, does indicate that the site contains natural amenities (i.e., woodlands) and environmental constraints (i.e., steep slopes, and unstable slopes). Please refer to the following section on "Earth" for detailed analysis of slope stability. 2. City of Tukwila Zoning Code Although the newly adopted Tukwila Zoning Code, 1982 designates the entire site Single Family Residential R -1 -12.0 District, the proponent had applied for a building permit prior to the adoption of the new zoning ordinance when the site was zoned Multiple Residence High (RMH) District; Low Apartments (R -4) District and One Family Dwellings (R -1) District. Consequently, the proposed project is regulated by the earlier zoning ordinance. This vested right to develop under the previous zoning designation was upheld by the Supreme Court in Allenbach v. Tukwila 101 Wn.2d 193 (1984), The proposed development conforms to the use regulations of the previous zoning designations. Please refer to Appendix A for description of the RMH, R -4 and R -1 Districts. 18 1961 CITY OF TUKWILA + NORTH LEGEND 0-1-9.6 ONE FAMILY DWELLINGS ONE FAMILYDWELLINGS THREEFAM,DWELLINGS LOW APARTMENTS MULT RES HIGH DENSITY NEIGHBORHOOD RETAIL BUSINESS LOCAL RETAIL BUSINESS PLANNED BUSINESS CENTERS RMH c-1 4-2 C-P-R ZONING. R.W. THORPE AND ASSOCIATES Approximately 2.9 acres of the north portion of the site is zoned RMH. The southeast 2.5 acres is zoned R -4 and the southwest 1.7 acres is zoned R -1. Zo III. EXISTING CONDITIONS, IMPACTS AND MITIGATING MEASURES A. INDEX GP ELEMENTS GP THE ENVIRONMENT B. ELEMENTS OF THE PHYSICAL ENVIRONMENT Page # Earth Geology Lif Soils Z4 Topography z7 Unique Features Z7 Erosion z-S Accretion /Avulsion NA Air Climate Quality Odor Microclimate Water 3'f 30 33 Surface water movement VS- Surface water quantity -SS- Surface water quality Runoff /Absorption 3 S Floods Groundwater quantity 3 g Public water supplies Sp Elora Numbers or diversity of species Unique species Agricultural Crops 21 Page # Fauna Numbers or diversity of species �Z- Unique species �2- Barriers and /or corridors 2r Fish or wildlife habitat NA Noise bitht and Glare SZ Land Tee S3 Natural Resources Rate of use Nonrenewable resources SS SS Risk of Explosion or Hazardous. Emissions �(Q B. ELEMENTS GE THE REMkN ENVIRGNMEN Population S6 Housinx 577 Employment NA Transpertat-ionfGircu1ation Vehicular transportation generated SS Parking facilities CaS Transportation systems 6"7 Movement /circulation of people and goods (,g Waterborne, rail and air traffic I/,A Traffic hazards 68 Public Services Fire 22. Page # Police 72 Schools '7 Z Parks and other recreational facilities 7 Maintenance '77 Other governmental services NA Eaerxv Amount required 79 Source /availability 79 Utilities Energy 79 Communications 4210 Water So Sewer $ L Solid Waste 634 Human Health Q Z Aesthetics MS- Archaeological/Historical ,/ 23 A. ELEMENTS OF THE PHYSICAL ENVIRONMENT Earth Geology and Soils Existing Conditions A geotechnical analysis of the site has been conducted by the soils engineering consultants (GeoEngineers, Inc). A copy of the report has been included as Appendix C. The site is located within a large, prehistoric, landslide zone. A substantial portion of property was affected by a landslide which occurred in 1960, as the result of excavation of borrow material which was used for fill in the Andover Industrial Park. Since construction of Interstate Highway 5, the stability of this property and adjacent properties have been improved by the remedial drainage measures which were installed and is maintained by the Washington State Department of Transportation during freeway construction. These facilities include systems of horizontal drains and vertical wells, a number of which exist along the eastern limits of the site. There are three benches on the site that appear to be manmade (See following "Topography" section). The presence of the benches is significant in that they may signify previous slide activity. Subsurface conditions were explored at the site by GeoEngineers, Inc., by CL drilling 8 borings. The records of borings taken previously in 1960 and 1961 were also examined. Three major soil units were identified as follows: Please refer to Geotechnical and Hydrological Study in Appendix C. UNIT A: (Upper Layer). Fill and /or slope debris, probably native to the site and consisting of loose to medium dense silty fine to medium sands. Thickness varies between 5 and 10 feet. 11111111111111111111111 NORTH SLOPE ANALYSIS R.W. THORPE AND ASSOCIATES UNIT B: (Middle Layer). Gray silt interbedded with fine to medium sand. The silt has some zones which contain a trace to some clay. Slicken sides are present throughout the Unit. UNIT C: (Lower Layer). Gray sandy silty gravel and gray gravelly sand with some silt. Consistency varies from dense to very dense and unit is generally saturated. The three units vary significantly both in depth and elevation across the site. The units tend to follow the existing topography and slope down to the east. Impacts Construction of the proposed development will require clearing and removal of vegetation, cutting, filling and reworking of soils to varying depths. The greatest depths of elevation are expected in building areas. Development of the property from a geotechnical standpoint is feasible providing that adequate maintenance of the existing deep drainage facilities is accomplished and that the installation of shallow drains on the upper portion of the site is accomplished. There are two principal mechanisms of slope instability which could damage the property. These include deep— seated sliding in a zone of soil from 30 to 50 feet below the surface and surficial sliding in the upper unit of soil, generally extending to a depth of about 10 feet below the present ground surface. Typically, for the soils encountered at the site, slopes should be stable up to 40 percent (2 1/2 to 1) in dry conditions and 20 percent (5 to 1) in wet conditions. Slopes at the site are generally on the order of 20 percent, steepening in places to 35 percent. Minimizing infiltration and subsurface flow will significantly improve the stability of the slopes. A uniform slope provides the mat favorable circumstances to minimize slope movements. The geotechnical consultants recommend that freestanding road- way cuts should be avoided and all cuts steeper than 3:1 (horizontal to vertical) (33 percent) should be supported by retaining walls. Only clean 26 granular soils are recommended for use behind the retaining walls. There- fore, it is anticipated that much of the backfill behind the walls will have to be imported to the site. Mitigating Measures All recommendations contained within the geotechnical report will be com- plied with by the project sponsor, including the following summarized below: a. The existing deep drainage facilities on State Highway right -of -way shall be continued to be monitored by the State of Washington Department of Transportation and maintained to prevent deterioration. b. Slope movement shall be monitored through an instrumentation program which is to be maintained through to the construction phase and beyond. c. Site grading shall be undertaken during the late summer - early fall months when the least amounts of rainfall can be expected and surface runoff and seepage from springs should be somewhat diminished. d. All cuts steeper than 3:1 horizontal to vertical (33 percent) shall be supported by retaining structures constructed and backfilled per specifications of the geotechnical report. e. Building foundations and drains shall be constructed per specifications of the geotechnical report. 2. See related Mitigating Measures listed under "Erosion ", page - , and "Surface Water Movement, Quantity, Quality, Runoff /Absorption ", page Unavoidable Adverse Impacts None., Topography Existing Conditions The site slopes moderately to the east and northeast with isolated areas becoming moderately steep. A large drainage swale transects the southern 2.% portion of the site. Slopes at the site are generally on the order of 20 percent, steepening in places to 35 percent. Three manmade benches are located on the site. The first bench was constructed during the installation of a sanitary sewer line which runs along the contour near the eastern boundary of the site. This bench essentially follows the sewer alignment to a point where the sewer line crosses the property line at the center of the eastern property line. Slopes downslope from the sewer bench in the southeast corner of the site are moderately steep. A second bench starts at the southern property line slightly upslope from the sewer bench and is oriented approximately parallel to the sewer bench for approximately one —third the length of the site at which point it disappears. The third bench is located in 'the center of the site and may have been constructed during installation of an old surface drain in this area. Impacts. The topography of the site will be altered in order to provide relatively level surfaces for construction purposes and through incorporation of retaining walls necessary to minimize potential slope movement. It has been recommended by the geotechnical consultants that cuts steeper than 33 percent be supported by retaining walls. A discussion of slope stability as a function of both slope and subsurface soil conditions is given under "Geology /Soils ", page - - -. Mitigating Measures Please refer to mitigating measures listed under "Geology /Soils ", page---. Unavoidable Adverse Impacts Alteration of topography in order to minimize potential slope movement: Erosion Existing Conditions Flow from spring activity on the moderately steep slopes has led to the development of several erosion gullies on the site. Dense vegetation assists in minimizing surface erosion on the majority of the site. 28 Evidence of previous slope instability is discussed under "Geology /Soils ", page - --- m raets Erosion will increase during the construction stages due to the removal of soil stabilizing vegetation and the disturbance of surficial soils. The greatest potential for erosion will be on the steeper slopes, particularly during periods of precipitation. Mitigating Measures 1. City of Tukwila requirements for grading and excavation will be followed to avoid erosion. 2. Plastic sheets and mulch should be used on portions of the exposed soil areas during construction to minimize erosion. 3. Landscaping shall be installed as soon as possible subsequent to completion of construction and should include plants suitable for the stabilization of the surface of steep slopes. 4. See related Mitigating Measures listed under "Geology and Soils ", page - - -, and "Surface Water Movement, Quantity, Quality, Runoff /Absorption ", page 5. Collection of seepage and springs will be done during construction to minimize surface flow that could cause erosion. 29 Air Air QualityfParticulates Existinz Conditions Particulates are minute particles of matter (often referred to as "dust ") suspended in the atmosphere.. The particles may be toxic or irritating to lung tissue. Particulates represent the visible component of air pollution locally, often seen as a "haze" during periods of air stagnation. Prevailing winds can play a role in distributing particulates from high concentration areas in central Seattle and Tacoma to the general vicinity within which the project site is located. Data accumulated by the Puget Sound Air Pollution Control Agency (PSAPCA) indicates that the concentration of suspended particulates in the Tukwila area has generally increased with increased urbanization of the Valley. The following table summarizes particulate data collected at an air monitoring station in the general vicinity: TABLE 1 Summary of Suspended Particulate 6oucentrations Tukwila Area Annual Geometrie Mean micrograms per cubic meter WA. State Location 1981 1980 1979 1978 1977 1976 1975 Std. Southcenter 47 48 50 46 48 45 34 60 (Source: Puget Sound Air Pollution Control Agency, Air Pollution Control Agency, Air Quality Data Summary - -1977, 1978, 1979, 1980 and 1981. No monitoring was done at the Southcenter site after 1981. The table indicates the particulate levels have been below the Washington State Ambient Air Quality Standards. Based on the proximity of the site to the monitoring stations, it is expected that the air quality conditions are similar to those recorded at the Southcenter monitoring site. 30 Automobile Generated Pollutants Existing Conditions Carbon Monoxide (CO) is a by- product of internal combustion and accumulates in areas of heavy, slowly moving traffic. CO can reduce the oxygen carrying capacity of blood, resulting in drowsiness and loss of vigor. Levels of CO vary by location more readily than particulates. Therefore, it is difficult to interpolate accurate readings to unmonitored. sites. In addition to carbon monoxide, automobiles emit two other chemicals, hydrocarbons, and nitrogen oxides, which react in the presence of sunlight to produce ozone. This reaction occurs over a period of time; therefore ozone concentrations are highest near major urban areas. Table 2 outlines the three automobile generated pollutants as measured at a monitoring station nearest the site by the State Department of Transportation. TABLE 2 Summary of- Automobile Generated Pollutant Levels General Vicinity of Protect Site kin PP10- Location Hydro Nitrogen Period Carbon Monoxide Carbons Dioxide (mo., yr) 1 Hour 8 Hour 6 -9 AM Study Period Max. Max. Avg. Avg. Puget Power 6/7 , 1977 3.2 2.0 0.37 0.02 Transformer Yd 3/4, 1977 4.2 3.3 0.28 (Renton) 10 /11, 1976 8.1 6.6 0.01 6/7 , 1976 2.2 1.3 -- 0.04 State Ambient Air Quality Standard 35.0 9.0 0.24 0.05/ Annual Average (Source: Washington State Department of Transportation 1977 Monitoring). No monitoring done after 1977. 1 31 Sulfur Dioxide Existing Conditions Sulfur Dioxide (SO2) pollution is produced through the burning of fossil fuels and is associated with a variety of respiratory ailments. The nearest station monitoring sulfur dioxide is located at the Duwamish Pump Station, 4500 East Marginal Way, Seattle, approximately 8 miles from the site. The sulfur dioxide levels measured (for 1980) are well below Washington State standards. According to Stuart Clark of DOE, sulfur dioxide is not anticipated to be a problem in Tukwila. Levels there should be equal or better than those recorded at the Duwamish Pump Station. Sulfur dioxide levels are typically high near pulp mills, or smelters; automobiles emit very little sulfur dioxide and are not considered as a source by the Department of Ecology. Impacts 1. Short -term generation of particulates will occur as construction commences. Dust particles would be raised by earthmoving activities. Suspended particulate concentrations will further increase due to project development. 2. Noxious odors would be emitted by diesel powered vehicles and from asphalt paving operations. 3. Some long -term increases in motor vehicle generated pollutants will occur due to the traffic generated by the proposed projects. Impacts would be greatest at identified points of congestion. 4. Insignificant increase in violation of Washington State standards for levels of hydrocarbons will occur due to the cumulative effects of this and other projects which generate automobile traffic. However, air quality impacts are not localized and would occur regardless of project site location. Mitigating Measures 1. Low- emission construction equipment could be used whenever feasible. 2. ' Measures to control construction dust such as: watering, cleaning and sweeping of streets at the end of hauling activities could be performed by the contractor. 3. Unnecessary motor vehicle engine idling during construction co„ uld be elminated; engines could be shut off except when moving vehicles. Unavoidable Adverse Impacts 1. Increased air pollution from automobile emissions will contribute insignificantly to hydrocarbon levels which already exceed Washington State Standards. 2. Insignificant increased particulate levels, which already exceed Washington State Standards, due to construction activity and additional traffic volumes. Odor Existing Conditions The site is currently devoid of any discernible ordors. Impacts 1. Automobile exhaust fumes may be perceived along the entrance driveway and parking areas. 2. Over the short term, odors will be attributable to construction vehicles, dust and asphalt paving during the construction phase. Mitigating Measures None. Unavoidable Adverse Environmental Impacts Short -term odors during construction. 33 Gate Existing Conditions The site is located in the Green River valley and has a typical Northwest Pacific Coast marine climate. During the fall and winter, prevailing winds are from the south and southwest, and during the late spring and summer from the north and northwest. Low level temperature inversions may occur in the Valley which, coupled with low wind speed, can result in the trapping of pollutants. This condition is most prevalent during the winter months. The Washington State Department of Ecology (DOE) has been designated as the responsible agency to obtain statewide air quality monitoring data needed to determine the status of compliance with the National Ambient Air Quality Standards. DOE's monitoring sites are located where worst air quality conditions are expected to exist. faets None. Mitigating Measures None. Unavoidable Adverse Impacts- None. Water Surface Water Movement; Quantity; Qnality; RnnofflAbsorption Exist-ins Conditions The drainage basin within which the site lies is bounded by Slade Way on the south and the extension of 158th Street on the north. The basin is 7.2 acres in area and is divided into two sub-basins. The south sub -basin is 4.4 acres in area, the north sub -area basin is 2.8 acres in area. The site is currently devoid of developed impervious surfaces. Surface runoff from the site flows to a lined ditch just east of the site. This ditch discharges to the existing deep storm system downstream of the site. Please refer to the Geotechnical and Hydrological Study, Appendix C of this EIS. A large drainage swale transects the southern portion of the site. Evidence of surface runoff during periods of precipitation is evident from the several erosional gullies observed at the site. Several seeps or springs have been observed on the site, some of which may' be originating from old horizontal drains. The other seeps may be natural or may also be originating from covered horizontal drains. A stormwater drain is located near the intersection of Slade Way and Southeast 53rd Street. A 15 inch storm sewer parallels Slade Way, transporting runoff to an existing deep storm system that was installed during the construction of 1-5. The 15 inch storm sewer runs above ground part of the way and was leaking several gallons per minute at the time it was observed, causing ponding in the immediate area. The deep drainage system consists of perforated drain pipe and runs generally in a north -south direction and terminates on site. No flow was observed in the portion of the perforated pipe system upstream of the point that the 15 inch culvert intersects the deep system. The stability of the slope of the site is largely influenced by surface runoff and near - surface infiltration of rainfall into the upper soils. h Based on the approximately 200 foot long scarp which was observed just east of Slade Way in 1982 and which is considered to be indicative of recent movement, it is evident that surficial movements are still relatively active in the southern portion of the property. fmpaets- l' Existing runoff and absorption characteristics would be altered by two aspects of the proposed development: removal of vegetation during site preparation, and introduction of impervious surfaces on the site in the foim of roads, parking areas and structures. Absorption would be reduced, and the rate and volume of runoff would be increased. Construction of the proposed development will not alter the existing drainage basin boundaries. Changes in potential peak flow of storm runoff due to building construction and paving will be controlled by the drainage retention and runoff control system. Surface water would be collected in a subsurface conduit system. The proposed drainage system includes storm drainage retention pipes and control structures which would store storm water and control the runoff rate to that which presently exists. Therefore, surface water would exit the site at approximately the same rate as it does under existing conditions. The introduction of impervious surfaces over a portion of the proposed development would reduce the area of exposed soils. Therefore, reduced quantities of sediment, nutrients and organic material, contained in the soil would be expected to leave the site in surface runoff. However, in place of these would be insignificant levels of contaminants more typical of residential developments: petroleum residues, traces of heavy metals, and sediments washed from roads and driveways. The increased quantity of impervious surfaces would increase the volume of stormwater runoff from the site. Use of pesticides, herbicides and fertilizers (if any) on yards or landscaping in common areas may occasionally contribute slight quantities of contaminants to stormwater that would not be removed by the proposed pollution separation devices. Also, the partial coverage of soils with asphalt paving and structures may result in slight elevation of temperature of runoff from these surfaces. Construction procedures, especially excavation, will result in slightly increased levels of suspended sediments, within the stormwater runoff. Clearing and grading would expose soils on the site to potential erosion b rainfall. Mitigating Measures 1. A stormwater detention system for a 10 year storm capable of detaining 2,500 cubic feet of water is proposed to be installed. Stormwater will be stored in underground storage pipes designed for a 10 year storm. The proposed stormwater collection and detention system would reduce the potential for adverse off -site impacts from runoff by controlling the rate of release to that which occurs under existing conditions. The length of time over which peak discharge would occur would be prolonged. All required temporary sedimentation and control facilities would be constructed and in operation prior to paving and building construction. The City of .Tukwila must approve stormwater drainage plans prior to issuance of the building permit. 2. Catch basins and oil /water separators are proposed within the on -site drainage collection system to separate sediments and petroleum residues from stormwater. On -site detention and the outlet control structure would further allow for separation of these pollutants from stormwater before release from the site. 3. Permanent French drains should be installed along the upslope sides of all parking areas, and along the east side of the condominium units. 4. Foundation drains should be installed and connected to drain lines along the east property line so the flow can be disposed of off the site. 37 5. A temporary storm management system and erosion control measures will be employed during construction. Where possible, natural vegetation for silt control shall be maintained. Proposed interim drainage control measures include placing strawbales in drainage ditches and directing runoff to two interim detention ponds. 6. All temporary siltation ponds shall be maintained in a satisfactory condition until such time as cleaning and /or construction is completed and permanent drainge facilities are operational. 7. Prior to site clearing, an interceptor trench should be installed at the toe of the roadway fill along the western boundary of the site. 8. Temporary drainage swale should, be installed to collect runoff immediately following site clearing and grubbing. 9. A portion of the existing perforated deep storm system will be abandoned and replaced by a new storm line to handle offsite runoff. The existing storm line that is above ground and leaking will be repaired. 10. The proponent would have maintenance responsibility for the drainage control facilities during construction, and it is proposed that the city assume maintenance responsibility for these facilities after completion of the development. Catch basins and oil /water separators should,be cleaned frequently and properly maintained to assure maximum attainable pollution separation. 11. Cleaning of streets and parking areas shall be undertaken whenever necessary during construction. 12. See related Mitigating Measures listed under "Geology and Soils ", page - -, and "Erosion ", page Groundwater Groundwater Movement,- Quantity; Quality Existing 6ondtttoas Groundwater levels at the proposal site have been measured by Geo Engineers, Inc. (See Appendix C) through the installation and monitoring of piezometers instrumentation within soil borings. The level of the water table at the site varies from 6 to approximately 40 feet below the ground surface, depending on the location of the boring. The groundwater surface 38 slopes downward to the north and east across the site. Groundwater conditions in the Unit C area changed significantly after installation of the vertical well and horizontal drain system during con- struction of I -5,1At the time previous borings (in 1960 and 1961) were observed at the site artesian conditions (groundwater levels above the ground surfaces) were reported. Data from piezometers northeast of the site indicates that the groundwater level was lowered between 15 and 65 feet between December 1966 and June 1968, due to the installation of the I- 5 drainage facilities. Data from the recent test borings indicate that the water levels across the site are lower than existed when the slide occurred in 1960. From the review of available data, there appears to have been no deep- seated instability on the site in the approximately 20 years since the deep drainage system was installed. As mentioned under "Water ", page ( / several seeps or springs have been observed at the site. Because the site is underlain by previously installed horizontal drains, it is possible that certain of the seeps may be originating from drains as well as natural sources. Groundwater quality has not been measured at the site. Impaet s- Direct surface runoff will increase and direct infiltration into the ground surface will decrease as a result of the introduction of proposed paved areas and structures. It could be expected that lawn areas and 39 landscaping, which would be periodically watered (particularly during dry weather), would introduce additional water to groundwater resources. The total contribution of the site itself to the groundwater supply is probably very small (although detailed investigations have not been conducted to define the extent of the groundwater basin). It is unlikely that the general direction of groundwater movement below the site will be altered by the proposal. From a geotechnical standpoint, it is of prime importance that the vertical well /horizontal drain system which was installed during construction of 1-5 be maintained in continued good working order. If the drainage system should deteriorate so that artesian pressures can again increase beneath the hillside, the risk of deep- seated and extensive earth movements can be expected to significantly increase. Mi t i�atta� Measures 1. See Mitigating Measures listed under "Geology /Soils ", page - - -, regarding maintenance of existing deep drainage facilities. 2. See Mitigating Measures listed under "Surface Water Movement, Quanity, Quality, Runoff /Absorption ", page - -, regarding surface drainage and storm water detention facilities (which will contribute to absorption and infiltration). 40. . Flora &xi st -into Conditions The site is largely vegetated with alder. According to the soils report, it appears the alder in the middle and eastern portions of the site have grown since the slide between 1960 and 1961. Undergrowth includes dense blackberry and some horsetails. Impacts All existing vegetation along the eastern portion of the site would be cleared and replaced with buildings, parking and ornamental vegetation. The western portion of the site would remain in its natural state. The appearance of a wooded valley wall would proportionately be reduced. Mitixating Measures 1. Ornamental vegetation shall include sycamore along Slade Way and along the parking lot. Vine, maple and flowering cherry would be interspersed among the buildings. Other plant materials would include platinia, rhododendron, mahonia, vibrurnum Davidi, ivy and lawn. 2. The southwestern portion of the site would remain in its natural state. - . Disturbed areas not proposed to be landscaped would be seeded with clover and rye. Area which would remain in its undisturbed sta approximately 2.3 acres. amounts to Unavoidable Adverse Impacts Removal of all natural vegetation from approximately 68 percent of the site. 41 Fauna Rxtstintt Conditions Wildlife on the site consists of birds, squirrels, rodents and possible raccoons. Though the wooded hillside is of considerable length, it is already impacted by automobile traffic along the freeway. Impacts The clearing of the vegetation for buildings, parking lots and landscaping will result in a loss of approximately 68 percent of the wildlife habitat on site. Present inhabitants of� site will be pressed into other areas of the wooded hillside. Some 'may perish in competition for the remaining habitat. Mitigating Measures 1. Approximately 2.3 acres or 32 percent of the site will remain in its natural state. Unavoidable Adverse impacts Removal of vegetation will result in the loss of animal habitat. Most species that currently utilize the area proposed for grading and development will be eliminated. Urban tolerant species will replace those species which are not. 42 Noise Existing Conditions Traffic on 1 -5 is the predominant source of noise affecting the site and adjoining properties. Existing day -night (dn) sound levels on the site are 65 to 72 dBA, and maximum nighttime sound levels are about 77 dBA. Archi- tectural noise mitigation is generally required to prevent significant impacts at sites where exterior day -night sound levels exceed 65 dBA. Day - night sound levels at the closest residential properties west of the site are 63 to 65 dBA, and maximum nighttime levels are about 72 dBA. These properties experience some noise impacts from 1 -5 traffic, although day - night sound levels below 65 dBA are considered acceptable according to EPA and HUD criteria. Existing noise levels were measured between Thursday, October 20 and Tuesday, October 25, 1983 at four locations shown in Figure 1. The measurements consisted of full 24 hour noise monitoring at three locations and 19 hours noise monitoring at the fourth location, where adverse weather curtailed the measurement. A Digital Acoustics- DA &O7P noise monitoring aystem was used for the measurements. Results of the measurements in hourly Leg, hourly Ldn are shown in appendix B, Figures 2 and 3. Locations 1 and 2 are on the site, and Locations 3 and 4 are off -site residences immediately west of the site which have views across the site toward 1 -5. The following is a summary of the measured day -night sound levels, Ldn, and nighttime maximum sound levels, Lmax: Existing exterior noise levels- dBA Location Description Ldn Night Lmax 1 SE part of site 72 77 2 NE part of site 65 (68 *) 77 3 Residence W of site 65 72 4 Residence SW of site 63 72 *Location 2 had partial topographic shielding of highway noise, which is estimated to have reduced Ldn by about 3 dBA compared to noise levels at a future upper story elevation. 43. I► tI 11 \\ —�i gi2111 ti • \\� '1 I4 • 1 ..... s, . hi \ _ ...: \-,.. • •.= tWa uI� M • It i1 EISKIP i ENNVii wwiefirio 114-al Inn 4111 senal II • a 1 �lii .Q�► f l i t Ml SCALE 0 100 200 900 V00 600 1 fah I • FEET 10111•1 ■11•11, Figure 1. Existing Noise Measurement Locations TOWNE, RICHARDS & CHAUDIERE, INC. Consultants in Sound & Vibration Ldn Site Acceptability Standard Not exceeding 65 dBA Acceptable Above 65 dBA but not exceeding 75 dBA Normally Unacceptable Above 75 dBA Unacceptable The standards require 5 dBA additional sound attenuation (reduction) for housing constructed on sites above 65 dBA but not exceeding 70 dBA, and 10 dBA additional attenuation for sites above 70 dBA but not exceeding 75 dBA. To prevent the probability of sleep interference from exceeding approximately 50 percent, studies* indicate that interior maximum sound levels, Lax, should be limited to about 50 dBA in bedrooms. *Miller, J.D., Effects of noise on people, Jeurnal of the Acoustical Society of America, 56, 3, September, 1974. Impacts - Exterior day -night sound levels on the site are in a range above 65 dBA where significant impacts on interior and exterior uses could occur unless mitigation is provided. An exterior -to- interior attenuation (noise reduction) of 30 dBA, about 5 dBA better than conventional construction, would provide generally acceptable interior noise levels according to EPA and sleep interference criteria. In addition, forced -air ventilation would be desirable so that windows would not have to be open for ventilation. Some exterior spaces could be shielded from freeway noise to prevent speech interference and annoyance, especially the proposed children's area. Physical site modifications and traffic generated by the project would result in negligible noise changes at off -site properties. Construction noise would largely be masked by the existing freeway noise. Interior Noise Levels On -Site Exterior noise levels at the proposed building locations were described in the Existing Noise Levels section. On the southeast part of the site (measurement Location 1), exterior day -night sound level, Ldn, was 72 dBA. On the northeast part of the site (measurement Location 2), exterior Ldn was 65 dBA at a first story elevation and about 68 dBA at higher 45 elevations. Nighttime maximum sound levels, Lmax, were 77 dBA at both locations. On the southern half of the site, exterior Ldn is in the range of 70 to 75 dBA were 10 dBA of additional exterior -to- interior sound attenuation would be required by the HUD standards cited previously if this were a HUD project. On the northern half of the site, exterior Ldn is in the range 65 to 70 dBA where 5 dBA of additional exterior -to interior sound attenuation would be required by the HUD standards. The HUD regional office considers the attenuation of conventional Northwest housing to be 25 dBA. Construction to meet the HUD standards must therefore provide exterior -to- interior attenuation of 35 dBA on the southern half of the site and 30 dBA on the northern half. A comparison of interior sound levels with and without added attenuation, and with open windows, is shown in the following table. 46 Interior sous& leve s dB Construction Part of site Ldn Night Lmax 10 dBA added attenuation* South 1/2 37 42 5. dBA added attenuation 42 47 Conventional construction 47 52 Open windows 62 67 5 dBa added attenuation* Conventional construction Open windows *HUD standard. North 1/2 38 47 43 52 58 67 This comparison indicates that an exterior -to- interior attenuation of 30 dBA (representing 5 dBA added attenuation) would provide generally acceptable interior noise levels (interior Ldn below 45 dBA and interior nighttime Lmax below 50 dBA). The construction to achieve this attenuation is discussed in the Mitigating Measures section. Because of the high interior noise levels with windows open, some form of forced -air ventilation wou_ ld be desira le_ especially for bedrooms, so that windows would not have to be opened for ventilation. Exterior Noise Levels On -Sete Exteriorr day -night sound levels, Ldn, were found to be 72 dBA on the southern part of the site and 65 to 68 dBA (depending on elevation) on the northern part of the site. These levels are in a range above 65 dBA where impacts (primarily speech interference and annoyance) are significant according to the criteria discussed previously. It is therefore recommended that noise mitigation for exterior spaces be considered, especially for the proposed children's area on the northeast part of the site. Possible mitigation is discussed in the Mitigating Measures section. Noise Level Changes Off -Site The proposed project is expected to cause negligible long -term noise changes at off -site properties. 47 The site currently has narrow -trunk alder growth which provides slight excess attenuation (reduction) of 1-5 freeway noise for properties west of the site. The trees were bare when monitored, and are estimated to provide at most 3 dBA of excess attenuation per 100 meters,* or about 2 to 3 dBA excess attenuation for properties west of the site. In summer, the excess attenuation would be slightly higher because of foliage. Construction of buildings on the site would provide partial shielding of views of the freeway, reducing freeway noise levels at properties to the west by about 3 dBA due to an approximate 50 percent shielding. This attenuation by the buildings would offset the loss of attenuation resulting from removal of existing trees on the site. The project would result in negligible noise increases along local streets due to increased traffic. It should be noted that highway traffic noise from 1-5 and SR 518 is predominant near the site, and that noise from the low to moderate traffic volumes on local streets is insignificant by comparison. Day -night sound levels, Ldn, from street traffic were computed using estimated 1987 daily traffic volumes with and without the proposed project as described in the Traffic Impact Analysis. It was assumed that 10 per- cent of traffic occurs during nighttime hours of 10 p.m. to 7 a.m., and that traffic speed is about 30 mph. The noise prediction was for a setback of 50 feet from street traffic. Where appropriate, the street traffic noise was combined with the noise from 1-5. *Beranek, L.L., Noise and Vibration Control, McGraw -Hill, New York, N.Y., 1971. 118 1987 day -night sound levels, dBA S treet noise bomb inert noise Street Freeway no-rae withoutfwith project wttheut/with proleet 53rd Ave. S. 65 55/56 66/66 north of site S. 160th St. west of site Slade Way and 54th Ave. S. south of site 54/55 54/55 72 44/45 72/72 The largest noise increase, 1 dBA, would occur along S. 160th Street west of the site. This amount of noise increase would not be noticeable. Noise increases on other more distant streets would also be negligible (less than 1 dBA increase). Construction Noise There would be temporary noise impacts during construction of the project. These impacts would be minimized by the fact that most construction would occur along the eastern part of the site, away from residences, and also because the existing freeway noise would mask much of the construction noise. The highest construction noise levels would be received at a residence at the corner of Slade Way and 54th Avenue S., about 100 feet from the southernmost proposed building. At this distance, construction noise levels could average between 59 and 82 dBA, depending on the activity and phase of construction, according to EPA data. Existing daytime noise levels from 1-5 average about 70 dBA in this area, as shown in Figure 2. It is therefore expected that the noisiest activities could exceed the existing traffic noise by up to 12 dBA, but that the typical construction noise would be close to the levels of existing noise. The closest residences west of the site would be about 200 feet or more from construction activity, and would receive estimated construction noise 49 levels between 53 and 76 dBA, again depending on the activity and phase of construction. Typical construction noise levels would also be similar to the existing freeway noise levels (about 60 to 65 dBA) at these locations. Construction could no.t occur before 7 a.m. on weekdays and 9 a.m. on weekends, or after 10 p.m., because of stringent State of Washington (WAC Chapter 173 -60) noise code restrictions on construction in residential areas during nighttime hours. Mitizatint Measures The following measures could be used to mitigate the noise impacts of the project : 1. Double wall construction and 1/2 inch gypsum wall boards shall be utilized. 2. Insulation shall include R -11 fiberglass batt. 3. Double glazed alumninum windows shall be included. 4. An exterior -to- interior sound attenuation of 30 dBA, about 5 dBA better than conventional construction, would provide generally acceptable interior noise levels according to the criteria cited. The additional 5 dBA attenuation can be achieved by using windows and glass doors having at least 5 dB better acoustical performance than conventional thermal insulated windows, as measured using sound transmission class (STC) rating or sound transmission loss curves. The windows and glass doors should have a minimum overall outside -to- inside thickness of 1 ", which can be achieved by using either double or triple glazing, since the middle glazing of a triple glazed window does not contribute significantly to acoustical performance. Each glazing should have a minimum thickness of 3/16 ", and the outside and inside glazings should have different thicknesses in order to avoid acoustic coupling. For example, a window can consist of 1/4" glass, 9/16" air space, and 3/16" glass. The glass should be set in resilient gaskets. Operable windows and exterior doors (including glass doors) show d be hinged rather than sliding, and shauld have resilient seals. Exterior doors sho d have automatic threshold drops or compressible neoprene threshold seals. These measures apply to rO north, south, and east facing windows and exterior doors. 5. East facing decks can be glass - enclosed, to effectively provide double windows between the outside and inside of the residential unit. If this construction is used, the 1" thickness is not necessary for the exterior or interior windows of the deck area. 6. Forced -air ventilation could be provided, especially to bedrooms, so that windows would not have to be opened for ventilation. Open win- dows provide only about 10 to 15 dBA outside -to- inside noise attenuation. 7. Noise levels could be reduced for some exterior spaces by use of barriers. For example, an eight foot high solid continuous fence around the eastern half of the proposed children's area would reduce the average noise levels by about 10 dBA, to about 55 dBA or less, which is an acceptable level for preventing noise - induced speech interference and annoyance outdoors. The barriers would have the disadvantage of reducing views from this area, however. Noise levels on the outdoor decks could be reduced by about 5 dBA by using a solid barrier around the deck. The barrier should be high enough to block views of the freeway from a typical user location (presumably seated), but need not be so high that it blocks views of the valley and moun- tains to the east. Acoustic barriers ma b constructed of wood with minimum thickness of 3/4 inch. Plywood, board - and - batten, or construction are acoustically acceptable. Barriers should have no gaps or openings, including the base. f3) 8. Construction should not occur before 7 a.m. on weekdays and 9 a.m. on weekends, or after 10 p.m., to prevent State noise code violations. In addition, any diesel or gasoline powered equipment used at the site could be required to have a proper muffler that is in good condition. Unavoidable Adverse Impacts The project would result in moderate unavoidable noise impacts to residents of the development because of the freeway noise which exists at the site. Construction activities would cause temporary noise impacts at the closest adjoining residen es. 5I Light- and Glare Existing Conditions There currently are not sources of light or glare on the site. Impacts The proposed development would result in the addition of light visible from the valley floor and the immediate vicinity. Light spill from residences should not be significant. Due to the distance between the valley floor and the site, glare resulting from reflections from windows is not expected to be a problem. The entrance driveway will feature entry lights. Headlights of vehicles entering and leaving the site will emit light at night. However, this light should not impact existing residences located to the south and southwest due to vegetation. Mitigating Measures 1. Perimeter landscaping will reduce light spillage. 2. Parking lot lighting could be directed so that no direct light spills off the site. 3. Light fixtures have been selected which would limit light spillage to 20 feet in height. Unavoidable Adverse Impacts None. Land Use Existinz Conditions The 7.08 acre site is presently undeveloped and heavily vegetated mainly with small caliper 2nd and /or 3rd growth alder. The general vicinity is comprised of single family residences and undeveloped land. The site is adjacent to the 405/1 -5 interchange. Commercial land uses exist across 405 and I -5 from tt} project. Impacts All proposed development is within the R -4 and RMH designated area. No development is planned under this proposal in the area designated R -1. The proposed development will be under the zoning ordinance in effect prior to the 1982 Zoning Code and map and will prevent development of anything more intense than single family residences in the vicinity of the site. Please refer to Zoning Map, page xx of this DEIS. The proposed project 'might be expected to exert pressure on surrounding property owners to upzone adjacent properties. However, due to the City's Comprehensive Land Use Plan Map and Zoning Map's single family designation of the surrounding area in 1982, it is highly improbable such potential comprehensive plan amendments and rezone requests would be successful. Mitizatinz Measures The buildings are sited along the east half of the property which provides a 15 to 35 foot topographic buffer from 53rd Avenue South. The grade for southern most buildings would be at nearly the same elevation as Slade Way. The proposed site plan provides a landscaped buffer along the western edge of the property partially screening the housing from commuters on Slade Way and 53rd Avenue South and residences in the McMicken Heights vicinity. Unavoidable Adverse Impacts None. ss J PUBLIC /SEMI PUBLIC FACILITY. lUNDEVELOPED LAND' LAND USE STUDY Natural Resources Existing Conditions There are no significant natural resources on site. Given that the site is undeveloped, there is currently no use of natural resources nor any depletion of non — renewable natural resources at the site. Impacts Construction of the buildings will consume natural resources, including energy and raw materials used in concrete, steel, aluminum, glass, copper and other materials of varying scarcity. Unavoidable Adverse Impacts Consumption of building materials and energy. 55 C. ELEMENTS AP THE HUMAN ENVIRONMENT Pope }ation Existing Conditions The 1980 population census count for the City of Tukwila was 3,578 representing only a 2 percent increase since 1970 compared to a 9.5 percent increase for Ring County. Comparatively, the vicinity (defined by SR 518, Interstate 5, S. 178th Street, Military Road and 42nd Avenue) in which the site is located has a population of 2,578, approximately 300 less than existed in 1976. Impact Population estimates for the proposed project were calculated by multiplying the number of dwelling units proposed, times 1.96 people per unit, (the 1980 average household size recorded for the City of Tukwila). The estimated population is 212. This figure assumes full occupancy. The project would average approximately 1 -1/3 bedrooms per unit. The estimated population increase due to the project represents a 5.6 percent increase in the total number of residents residing within the City. This is approximately 3 times the increase in population the City experienced between 1970 and 1980. Mitigating Measures None. Unavoidable Adverse Impacts None. Housing Existing F,onditions The site is presently undeveloped. The 1980 Housing count in the City of Tukwila was 1938 dwelling units, 265 more than recorded in 1970, an in- crease in housing stock of approximately 16 percent. The vacancy rate of the City of Tukwila was approximately 6 percent. This is comparable to King County's vacancy rate of 5 percent. Impacts The proposed development of 18 6- plexes would occur in a predominately single family and undeveloped area of the Tukwila Planning Area. The site is adjacent to the 405/1 -5 interchange. Commercial land uses exist across 405 and I -5 from to project. Please refer to the Existing Land Use Map, page xx of this DEIS. Project development would add 108 dwelling units representing a 5.3 percent increase in the City's housing stock. The proposed density would be 15.25 dwelling units per acre. Mitigating Measures The proposed site plan provides a landscaped buffer along the western edge of the property, partially screening the housing from commuters on Slade Way and 53rd Avenue South and residences in the McMicken Heights Area. The proposed design with the housing along the easterly portion of the site will provide between a 15 and 35 foot grade differential from 53rd Avenue South. Rooflines will extend up to 15 feet above street grade on 53rd and up to 35 feet above street grade on Slade Way. Unavoidable Adverse Impacts None. 57 Transportation/Circulation Vehicular Transportation Generated Extstin= Conditions depicts the street system in the site vicinity which provides access from the Puget Sound /Seattle area region as well as the local Tukwila /McMicken Heights neighborhood. Interstate 5 (I -5) provides the major north -south traffic corridor for regional travel in the site vicinity while Pacific Highway S., west of the site, provides some regional and more local through travel in the area. To the north of the site, SR 518/I -405 provides an east -west traffic link between Burien and Renton as well as direct access into Jackson International Airport. The City of Bellevue and other points on the east side are reached via 1-405. More immediate to the site, Klickitat Drive provides a collector arterial function between and including 51st Avenue S. north of SR 518 and Southcenter Parkway. It is a two -lane street with 4 -6' paved and gravel shoulders in the vicinity of 53rd Avenue S., and the project site. Its roadway surface is in good condition. Except for the SR 518 eastbound off - ramp, 53rd Avenue S., and the 1-5 southbound on -ramp, there are no other direct access locations onto Klickitat Drive. Adjacent land use to the north and east of Klickitat is primarily state highway right of way, while that to the south and west is nondirect access residential land use. 53rd Avenue S., south of Klickitat, rises southbound at approximately 4 -6 percent to S. 158th Street. It is in fair to good condition with adequate gravel shoulders. Its intersection with S. 158th Street is a "T" intersection with the south and west legs controlled by STOP signs. South of 158th Street, the roadway curves to the east, becoming Slade Way which continues on a downgrade to the east and narrows as it turns sharply to the south near I -5. The section of Slade Way on the 54th Avenue South alignment is a very narrow section, little more than one lane in width. Additionally, shoulders are narrow to nonexistent with a tree growing near the edge of the pavement along the east side of the road. Farther south, Slade Way /54th Avenue South, swings west again and becomes 53rd Avenue South, which provides local access to an established residential area. The section of roadway near 166th Street has recently been widened by the City of Tukwila to a standard 26 -foot wide section. South 160th Street, South 164th Street and South 170th Street provide the primary east -west local access roads in the McMicken Heights area between the project site, Military Road and Pacific Highway South. These streets are generally two -lane residential roadways in fair to good condition with some local exceptions such as potholes and /or poor pavement. Shoulder width, although not narrow, is often used for residential vehicular parking. In general, residences in the vicinity front relatively close to the roadway edge, typical of numerous established medium density residential neighborhoods throughout the Puget Sound area. Military Road is generally a 2 -lane roadway, running northwest to southeast, with left -turn channelization provided at selected intersections. Traffic signals control intersections with South 164th Street /42nd Avenue South as well as South 176th Street. It is currently in good condition within the project study area. Traffic Volumes. Current traffic count information was collected from the City of Tukwila and King County. The traffic volumes represent counts taken in 1981, 1982 and 1983. Where available information was incomplete, the TRANSPO Group estimated the current traffic volume based on neighboring volumes and field observations. Figure 3 illustrates these existing daily traffic volumes. As shown on volumes are in the vicinity streets carrying the highest traffic Southcenter Parkway /Southcenter Boulevard area where volumes are typically in excess of 20,000 vehicles per day (vpd). West of the project site, traffic volumes on most local streets range from 200 vpd to about 4000 vpd. Most fall within the 500 to 2100 vpd range. This is 59 typical of established residential neighborhood traffic patterns where some streets function as neighborhood collectors, such as South 160th Street, South 170th Street and 53rd Avenue South, adjacent to the project site. Other streets such as South 164th and South 166th Streets function in a more locally- oriented manner, primarily serving the transportation needs of residents on that street. 53rd Avenue South, adjacent to the project site carries about 2200 vpd; however, south of South 158th Street, where 53rd Avenue transitions into Slade Way, the volume drops sharply to about 200 vpd. This indicates that the primary travel pattern is to the west from 53rd Avenue to South 158th /160th Street. 158th /160th Street carries about 2100 vpd near 53rd Avenue South. Rlickitat Drive near 53rd Avenue South and the project site carries between 13,000 - 15,000 vpd, growing to over 20,000 vpd south of the 1-5 southbound on -ramp. These volumes are consistent with those observed on many other collector arterials. The TRANSPO Group made evening peak period traffic counts at the intersections of 53rd Avenue South with South 158th Street and Klickitat Drive as well as Klickitat Drive with the southbound 1-5 on -ramp adjacent to the project. These volumes were generally about 9 to 10 percent of the daily traffic volume estimates shown on Figure 3 of appendix E. Techniques have been developed to assess the levels of congestion that result with different street and traffic volume conditions. These techniques are described in the Ritthway Gapaeity Manual and the Traffic Lngineerint Handbook and are referred to as levels of service (LOS) which range from LOS A which is very good, to LOS F which reflects a traffic flow that has deteriorated to a start- and -stop condition. In urban areas most traffic engineers design improvements to operate at LOS C, but consider LOS D acceptable during peak periods as long as these conditions do not extend longer than one hour within the peak period. Currently, it is estimated that the intersections counted by the TRANSPO Group operate at acceptable levels of service during the PM peak hour. The busiest of these intersections was the intersection of 53rd Avenue South with Klickitat Drive. Using TRB Gircular 21.2 Techniques for Unsitnalized T- intersections, the resulting level of service calculation indicated that right and left turns from northbound 53rd Avenue South are currently operating at LOS C. This indicates that delays experienced by drivers attempting to make these movements are within an average range, and not uncommon to numerous other locations throughout the area. Left turns from Klickitat onto southbound 53rd Avenue were calculated to operate at LOS A, indicating little or no delay. While these calculations indicate average conditions within the peak hour, observations by the TRANSPO Group indicated that sporadic backups behind left- turning traffic from Klickitat to 53rd Avenue extended to as many as 8 or 9 vehicles at times; however, these backups only lasted a minute or less as a maximum, typically clearing within a few seconds after the lead left -turn vehicle completed its movement. In addition, the wide lane and shoulder for westbound traffic on Klickitat allowed some vehicles to pass the left- turning vehicle on the right. While existing striping does not encourage this movement, it would appear that adequate space is available to restripe the east leg of Klickitat with little if any widening to allow for left -turn channelization, thereby eliminating delays to thru traffic as a result of left- turning traffic ahead. All other intersections in the immediate site vicinity operate well within the accepted range of delays for LOS A conditions. Planned and Proxrammed Traffic Improvements- In order to accurately evaluate traffic impacts at the time the project is constructed, an attempt was made to determine the street system which would likely be in place for the project-target year even if the project were not constructed. A review of the current 1984 through 1989 Six Year Transportation Improvement Program (TIP) for the City of Tukwila was made. The following projects in the immediate site vicinity were identified which would impact or be impacted by the proposed Valley View Estates development. The work tasks for all projects involved grading, drainage, light bituminous surface treatment, A.C. or P.C.C. pavement, sealcoat, curb, gutter, sidewalks, lighting and signing. 61. The project limits are shown below: o 160th Street, 51st to 53rd Avenue o 54th Avenue, Slade Way to 166th Street o 53rd Avenue, 160th Street to Klickitat Drive o Slade Way, 54th Avenue to 160th Street Of these, 160th Street from 51st to 53rd Avenue is planned prior to completion of the Valley View Estates project. Most other improvements would be contingent on the formation of.a Local Improvement District .(LID). Portions of 54th Avenue near 166th Street are currently being improved, including widening and curve improvements to eliminate a sharp, narrow curve between 166th and 54th. Figure 6, Project- Generated Traffic volumes, depicts the daily and evening peak hour traffic volumes associated with the distribution of travel described above on the local roadway system. This traffic assignment illustrates the difference in travel patterns between composite daily traffic and evening peak hour traffic. Evening peak hour traffic assignment is generally more heavily oriented toward routes serving primary employment centers (i.e., Seattle 1 -5 N and SR 99 -N), Bellevue /Renton 1- 405 E). Daily traffic, in addition to worker commute trips, reflects social /recreational and retail travel. The daily traffic assignment in Figure 6 therefore reflects travel to and from community retail centers located at SR 99 and 160th, along Military Road at South 164th and in the Southcenter /Parkway Plaza vicinity. Traffic volumes associated with each trip purpose were generally assigned to the one or two primary traffic carrying routes between the development and the trip destination. This technique reflects a worst case traffic volume on these primary traffic - carrying facilities. It is acknowledged that some traffic may use other minor roads in the vicinity (i.e., 164th Street and 166th Street and others); however, these traffic volumes would be very minor and would cause no_ ti�ble increase in either traffic or congestion at intersecting roads. Impacts A trip generation rate of 8.0 daily vehicle trip ends (VTE) per DU was selected for use in this study both to reflect local experience with similar developments and to indicate a worst case assumption with regard to potential traffic impacts. For the purposes of this study, worst case is defined as the high end of the reasonably expected range of conditions. Corresponding to this daily trip generation rate, a PM peak hour rate of 0.8 VTE per DU was selected. This is consistent with numerous observations in residential areas which indicate that approximately 10 percent of the daily- travel occurs during the evening peak hour. The above described trip generation rates per dwelling unit were applied to the 108 units proposed for the Valley View Estates residential project. Based on this, the TRANSPO Group estimates that approximately 900 daily vehicle trips and 90 evening peak hour vehicle trips would be generated by this project at full occupancy. epicts the impact of the project traffic on traffic conditions likely to exist in 1987, showing both 1987 daily traffic volumes with and without the Valley View Estates project. o 53rd Avenue: 158th Street to Klickitat Drive -- +530 vpd, + 23 percent o 158th /160th Street: 53rd Avenue to 51st Avenue + 340 vpd, + 16 percent o 160th Street: 42nd Avenue to 51st Avenue -- 300 vpd, + 16 percent o Slade Way /54th Avenue: 170th Street to project -- + 30 vpd, + 15 percent o 170th Street: 51st Avenue to 53rd Avenue -- + 30 vpd, + 6 percent. It should be noted that the 15 percent and 6 percent increases shown for Slade Way, 53rd Avenue South and 170th Street between 51st Avenue and the project are a result of a total of 30 vehicles assigned to that route on a daily basis. The relatively high percent impacts are due to the low traffic volumes currently using these roadways. The 158th /160th Street corridor would be the primary local street artery for traffic destined or 63 originating locally west of the site, including Pacific Highway South in Burien. Although the 16 percent increase in traffic volumes on this route will be noticeable and would generally be classified as significant, the roadway is fully capable of comfortably carrying the forecasted traffic both with and without the proposed project. Therefore, significant adverse impacts associated with these increased traffic volumes are not anticipated. 53rd Avenue South between Klickitat and the project site is expected to increase in volume by 23 percent over 1987 conditions without the proposed project. Again, however, this increase is well within the traffic-carrying capabilities of the two -lane roadway, and no significant adverse impacts would be anticipated. Typically, 5,000 to 7,000 vpd would be considered desirable maximums for traffic volumes on similarly functioning streets by many jurisdictions. It should be noted, however, that "desirability" varies between neighborhoods and depends on many factors including driver expectations and conflicting pedestrian activity. The location identified in the Existing Conditions section of this report as being a potential problem, 53rd Avenue South, intersecting with Klickitat Drive, would experience no significant decrease in level of service as a result of project - generated traffic. The critical movement from a congestion standpoint as calculated using Circular 212 methodology would be the northbound left turn from 53rd Avenue S., as mentioned in the Existing Conditions section. This movement would operate in the LOS D range both with and without,the proposed project (existing conditions calculations indicated LOS C- operations). The observed westbound left -turn queues which occasionally back up in excess of 7 or 8 vehicles now could become somewhat longer as a result of non - project traffic growth; however, the incremental difference in this queuing situation as a result of this project would be unnoticeable. Traffic volumes on Klickitat Drive both east and west of 53rd Avenue South would be impacted approximately 2 per- cent as a result of project - generated traffic. This is well within the 5 percent rule of thumb associated with the daily variation in traffic volumes. The locations of the proposed driveways to the project both off 53rd Avenue South and Slade Way appear to pose no special problems or concerns relative to either sight distance or traffic volumes. About three - fourths of the total daily project traffic will utilize the northerly driveway along 53rd Avenue South, while about one - fourth will utilize the two driveways along Slade Way. The westerly driveway off Slade Way is a dead end access to 12 of the units, while the easterly driveway is a thru access continuing northward to the 53rd Avenue access point. Mitigating Measures o A left -turn lane for westbound -to- southbound left turns from Rlickitat Drive to 53rd Avenue South would be desirable to eliminate conflicts between left- turning traffic and westbound thru traffic. Traffic acci- dents over the last three years shows a consistent pattern of rear -end accidents at this location which would be addressed and reduced signi- ficantly by such an improvement. This improvement would be considered desirable to improve existing intersection operation as well as in the future with and without the project. Project generated traffic will add about 2 percent additional traffic on the intersection approach both daily and during the peak hour. However, it will increase the left -turn component of this approach volume about 25 percent. o Assure that project driveway locations are at least 150 feet away from the nearest intersection. The most current site plan available indicates that this condition is met by the current design. Unavoidable Adverse Impacts None. Parking Existing Conditions Since the project site is currently undeveloped, there is no parking use of the site. Very sparse on- street parking was observed in the immediate site vicinity as residential development is sparse as well. To the west, in McMicken Heights, between the project site and Military Road, as well as between Military Road and Pacific Highway South, on- street parking was generally sparse and associated with close fronting residences along the various streets. There was little evidence of any parking which encroached into the travel lanes for the vicinity streets. There was no parking observed along Klickitat Drive near the project site as there is currently no frontage of any traffic generating activity. Impacts A total of 162 parking spaces are currently to be supplied on -site. This indicates a ratio of 1.5 spaces per dwelling unit, which is typical for similar suburban residential developments, and consistent with section 18.56 of the zoning code under which this project will be reviewed. The proposed parking supply and its layout should be adequate to contain "everyday" parking demand completely on -site. We would not anticipate any parking "spillover" to 53rd Avenue S., Klickitat Drive or Slade Way. There may be a few days during the year when some overflow parking may be required due to social activities. The site plan indicates that there are some areas on -site which could be designed to accommodate overflow parking should it be required. Allowing for some on -site overflow in the site design would help ensure that project parking demand would not impact Slade Way or 53rd Avenue South, even during peak demand periods. Mitigating Measures o Provide on -site parking overflow areas to accommodate frequent parking demand conditions in excess of 1.5 per dwelling unit. There appears to be capacity for about 20 vehicles in the area designated RMH in the western portion of the site adjacent to 53rd Avenue. o Do not allow parking spaces on -site to be reserved for any particular residential unit. This will allow flexibility to accommodate fluctuating demands in the primary designated parking areas. o Parking of recreational vehicles or trailers should be accommodated off -site to ensure the residential and visitor parking flexibility is maintained. Unavoidable Adverse Impacts Potential spillover onto 53rd Avenue South, Klickitat Drive or Slade Way due to possible social activity. Transportation Systems Existing Conditions The project vicinity is currently well served by existing Metro Transit routes. Two transit routes pass directly adjacent to the site on Rlickitat, routes 240 and 241. Route 240 utilizes 53rd Avenue South, 51st Avenue South and South 170th Street to Pacific Highway South through the McMicken Heights neighborhood. Route 240 serves Bellevue and Burien, running on 1 -hour off -peak headways and 1/2 hour peak headways. Route 241 bypasses McMicken Heights and continues west on Klickitat via SR 518 to Pacific Highway South. These and other transit routes in the general project vicinity are shown on Figure 5. Impacts Although, in order to reflect a worst case traffic impact analysis, all trips were assumed to occur via auto, it is acknowledged that a certain small percentage of the trips to the project site would arrive by transit. Since one transit route passes by the site along 53rd Avenue and others are accessible nearby in the Southcenter vicinity, it would be expected that some riders may find it convenient to utilize this mode. It is estimated that less than 5 percent of the total trips to and from the Valley View projects would be made by transit patrons. This would indicate that no more than 50 daily trips (25 arrivals, 25 departures) would be made by transit users. Metro Transit would likely view this impact as positive rather than adverse. Mitigating Measures o W with Metro Transit to ensure a safe, convenient bus stop location for project transit patrons adjacent to the, Valley View Estates site. Unavoidable Adverse Impacts None. 67 Pedestrian and. Bicycle Travel Existing Conditions Field observations made during peak hours and at various times of the day including weekends, showed that there was no significant numbers of pedestrians or bicyclists in the immediate site vicinity. In areas where traditional activity generation exist, such as community shopping centers, more activity was observed; however, it was still judged to be light. A few pedestrians were observed in the residential neighborhood to the southwest; however, the activity would be again described as very light. The 1979 Transportation Improvement Plan indicated that there are no bikeways along the arterial system within the City and no current plans to add them along major streets in the project vicinity. Physical factors, such as steep terrain, limit bicycle use as a commute mode. Impacts A small percentage of the total travel associated with the Valley View Estates residential development would be expected to be generated by pedestrians or bicyclists. Its relative isolation from any designated pedestrian or bicycle facilities would tend to discourage this type of travel for most trip purposes. The expected level of increased activity of both pedestrian and bicycle travel associated with the Valley View Estates project should not result in significant adverse impacts. Mitigating Measures None. Unavoidable Adverse Impacts None. Traffic Hazards Existing Conditions Traffic accident data over the period from 1980 through September 1983 was examined based on information supplied by the King County Traffic Engineer and the City of Tukwila. The average annual accident occurrence is 68 depicted on Figure 4 for intersections in the project vicinity. Near the site, the intersection of 53rd Avenue South with South 158th Street did not experience a reported accident in the study period. An average experience of 2.7 accidents annually occurred at 53rd Avenue South and Klickitat Drive, while 0.3 accidents per.year occurred at the intersection of Klickitat Drive with the I -5 southbound ramp and the intersection of Klickitat Drive with Southcenter Parkway. In the entire study area depicted on Figure 4, approximately 4 percent of the accidents occurring during the study period involved pedestrians. Of these, nearly half of the pedestrian accidents occurred on 170th Street at Military Road and 51st Avenue South. Since this is a Metro bus route, it is likely that some accidents may be attributable to pedestrians associated with transit, although the accident records were not detailed enough to discern this. Impacts There do not appear to be any unusual safety hazards associated with the design or siting of the Valley View Estates multi - family housing development, and consequently, the development is not expected to measurably increase the safety hazard potential on most surrounding streets. Traffic accidents in the vicinity may be expected to increase in proportion to the increase in traffic volumes on streets surrounding the proposed development. However, it is difficult to estimate exactly how large this increase may be. In addition to accidents at nearby intersections increasing at a constant rate, there will be an increased potential for accidents associated with the driveway openings for the development site, due to new turning movement conflicts. Potential conflicting traffic volumes at these locations indicate that the increase would be very minor. Although pedestrian traffic along streets in the vicinity has been observed to be very light, there would be an increased potential for vehicle - pedestrian conflicts along thesle roadways. The contribution of project traffic along these roadways in the McMicken Heights neighborhood would be very small, however, and therefore the fraction of the small potential increase in accidents attributable to the project - generated traffic would generally be unnoticeably small. 69 Mitigatinx Measures o A left -turn lane for westbound -to- southbound left turns from Klickitat Drive to 53rd Avenue S. would be desirable to eliminate conflicts between left - turning traffic and westbound thru traffic. Traffic accident experience over the last three years shows a consistent pattern of rear -end accidents at this location which would be addressed and reduced significantly by such an improvement. This improvement would be considered desirable to improve existing intersection operation as well as in the future with or without the project. Project - generated traffic will add about 2 percent additional traffic on this intersection approach, both daily and during the peak hour; however, it will increase the left -turn component of this approach volume about 25 percent. Unavoidable Adverse Impacts Traffic accidents may be expected to increase in some proportion to the increase in traffic volumes on streets surrounding the proposed development. 70 Public Services Fire Services Existinz Conditions There is no evidence of any fire on the undeveloped site. Fire protection to the site is provided by the Tukwila-Fire Department. Fire and emergency response time to this area is estimated to average 3 to 4 minutes. The fire rating in Tukwila is Class 4 in a scale of 1 to 10 with 1 as excellent. Impacts The proposed condominium development represents an increase in fire service demand. The proposed on -site system would comply with City of Tukwila fire flow and hydrant- spacing requirements, as well as with the requirements of the Washington State Department of Social and Health Services. According to Washington Survey and Rating Bureau criteria, approximately 2100 gpm (see appendix for calculations) is the required fire flow for multi - family developments of this type. The proposed system would meet the minimum criteria. Projected domestic water usage for the site should not exceed 0.04 mgd on a peak day (see appendix for calculations). Mitigating Measures 1. Provide one approved fire extinguisher in each unit. 2. Provide smoke detectors per the Uniform Building Code Section 1210. 3. Certain driving and parking areas may be declared "fire lane - no parking" areas per Ordinance 1110. 4. A 20 foot wide unobstructed driving lanes with 35 foot turning radius will be required throughout. 5. ,Proud protective curbs or guard posts for all sprinkler valves, hydrants, gas meters and transformers. Unavoidable Adverse Impacts Increased demand for fire service. 71 Police Service Existing Conditions Police protection in the vicinity is provided by the City of Tukwila Police Department. Emergency response time for the area on the average is 3 to 5 minutes. According to the Police Department's operations, the present level of police service in the City is adequate since the site is presently undeveloped, there is no demand for police service. Impacts Owner occupied condominiums have presented little in the way of problems for the Police Department. Should the owners buy the units as investment property, and subsequently rent them out, a different situation exists. Apartment dwellers (renters) seem to be a much above the norm (calls for police services) as the condominium owners are below it. A complex of the size proposed would not necessitate the acquisition of additional personnel, but may be reflected in slightly increased response times throughout the city. Mitigating Measures 1. A close working relationship between the developers and the Police department's Crime Prevention Officer,should maintained throughout the planning and building phases of this project. With the Crime Prevention Officer's assistance, crime and personal safety risks can be held at a minimum. 2. Adequate parking on site should be provided to minimize the need for street parking - a source of vehicle accidents, pedestrian accidents, auto thefts and car prowl accidents. Unavoidable Adverse Impacts Increased demand for police service. Schools Existing Conditions The site is within the Highline School District. The general vicinity is served by Valley View Elementary and Bow Lake Elementary, Chinook Middle 72 School and Tyee High School. The current enrollments and capacities of these schools are indicated in the following table: School3 Schools serving Vicinity of Valley View Site 4 Enrollment (Oct. 1984) • Capacity 2 Valley View Elementary1 292 250 Bow Lake Elementary 363 500 Chinook Middle School 441 875 Tyee High School 780 750 1 Valley View Elementary has an open concept unlike other schools in Dis- trict. Consequently, there is a high demand and there is a waiting list for enrollment. 2 Capacity is based on Highline School District standards of 25 students per classroom. 3 Portable classrooms are utilized in schools where enrollment has exceeded capacity. 4 Phone conversation with Dorris Brown, Facilities and Planning Office for Highline School District. June 18, 1984. Impacts Based on the population distribution by age provided in the 1980 census, it is estimated approximately 27 school aged children could be expected to reside in the proposed development. Bow Lake Elementary and Chinook Middle School can easily absorb the estimated increase in enrollment created by the proposed development. Approximately 7 high school aged children could be expected to reside in the proposed development representing an increase in enrollment at Tyee High School of less than one percent. 7 students represents a twenty -eight percent increase in demand for one additional classroom or portable classroom. Mitigating Measures None. -verse Impacts - .. increase in demand for an additional classroom at Tyee High School. _73 Parks and Recreation Existing Conditions The neighborhood in which the site is located is called Crestview in the City of Tukwila Park and Open Space Program, 1976 -81. The neighborhood is bounded by 1 -5, SR 518, 42nd Avenue South, Military Road, and South 178th Street. The only recreational facility within the neighborhood is the 6.5 acre Crestwood Elementary School playfield located at the southeast corner of South 160th Street and 42nd Avenue South, approximately one -half mile west of the site. Based on the National Parks and Recreation Standards used in the City's Park Plan, the Crestview Elementary School playfield serves as a neighborhood playfield for the major portion of Crestview neighborhood. Due to the poor pedestrian and bicycle access between the playfield and the subject site, and the lack of any park facility in the neighborhood, a proposed 5 acre neighborhood park was identified within the Park Plan west of Slade Way. Basis for space standards are as follows: Park and Playfield Neighborhood Neighborhood Crestview Space Standard Park Playfield Neighborhood (Crestview Elementary School Playfield) Service radius 1/4 -1/2 mile 1/4 -1/2 mile 0 -1 (walking distance) Population served 3000 -7000 5000 2578 Size range 3 -10 acres 3 -7 acres 6.5 acres Acreage /Population 1 -2 a. /1000 p. 1.25 a /1000 p. 2.52 a. /1000 p. A 25 -acre community park is also proposed at the southern end of the neighborhood which would also serve the McMicken Heights, Highline, and Bow Lake neighborhoods. Neither of the proposed parks have been developed, nor are they identified 71 for development in the foreseeable future. Under section 18.60.200 "Recreation Space in Multiple Family Districts" of the applicable Tukwila Zoning Code, the following minimum requirements shall be required of the proposed project. 1. For each proposed dwelling unit in the multiple family structure com- plex or development, a minimum of two hundred square feet of recreation space shall be provided. Any multiple family structure, complex, or development shall provide at least one thousand square feet of recrea- tion space. a. No more than fifty percent of the required recreation space may be indoor or covered space. b. No more than fifty percent of the required space may be used for single - purpose permanent facilities such as swimming pools, tennis courts, and similar facilities. c. Apartment complexes which provide dwelling units with two or more bedrooms shall provide adequate recreation space for children. Such space shall be at least twenty -five percent, but not more than fifty percent of the total recreation space required under subsection (1) above and shall be designed, located, and maintained in a safe condition. d. No more than fifty percent of the open or uncovered recreation space requirement may be located on slopes greater than four hori- zontal to one vertical (four -to -one slope). e. The front, rear, and side yard setbacks required by the applicable zoning district shall not qualify as recreation space. f. In the event. the total area required under subsection (1) above is less than three thousand square feet, that portion required to be outdoor and uncovered shall be one continuous parcel of land. g. Adequate fencing, plant screening, or other buffer shall separate the recreation space from public streets, parking areas, or driveways. 2. It shall be the duty of the Planning Commission, acting as a Board of Architectural Review, to review all recreation space plans for design, location, function, adequacy, and compliance with the above - stated standards prior to issuance of the building permit for any multiple 76 family structure, complex, or development. (Ordinance 1040 S3, 1977). Impacts The proposed project would attract approximately 212 new residents to the northeast portion of the neighborhood. Although the site is within the service radius of the playfield, pedestrian and bicycle access between the site and playfield is poor. The proposed project will increase the demand for a neighborhood park from a minimum of 3.2 acres to a minimum demand for 3.5 acres.1 1 Based on 1.25 acres of park per 1000 population. Mititatinft Measures 1. A 6,175 square foot children's play area is proposed which would include an open play area, sandbox, and other play equipment. 2. All requirements under Section 18.60.200 "Recreation Space in Multiple Family Districts" will be complied with. Unavoidable Adverse Impacts Increase demand for neighborhood park area in the Crestview neighborhood by approximately nine percent. Maintenance Exist-ine Conditions The City of Tukwila presently maintains the public roads in the vicinity of the site. Impacts The City of Tukwila will maintain roadway and water system facilities. The Val Vue Sewer District will serve the sewer system. During construction, street sweeping and ditch cleaning will be undertaken by the developer. Mitigating Measures 1. Cover the trucks carrying excavation loads with canvas or tarp. 2. The developer could provide regular street cleaning during construction. 77 Unavoidable Adverse Impacts Increased demand for long -term city maintenance. 78 Utilities Energy Existing Conditions There are no existing demands for energy from the site. Impacts During construction, energy will be committed in the form of equipment operation, motor fuels and manufactured materials. Energy consumed during this period will be typical of standard residential construction. However, because of the multiple family density on portions of the site, energy expenditure for construction per dwelling unit would be less than would be expended for a single family development. According to residential consumption data for all- electric apartments provided by Seattle City Light, an average of 950 kilowatt hours (kwh) per month or 11,400 kwh annually are consumed. At this rate, the 108 units of the proposal would consume about 102,600 kwh monthly or 1,231,200 kwh annually if fully occupied. Energy expenditure in terms of transportation related to work, shopping and social purposes will create a long -term energy commitment. Mitigating Measures 1. Insulated walls, floors, roof and glass could be used through the structures. 2. An energy analysis of building design elements could be undertaken . to assess the feasibility of reducing long -term demand, e.g. passive solar energy systems. Unavoidable Adverse Impacts Increased energy demand on the site in both the short and long terms. Communication Existing Conditions Telephone service to the site would be provided by Pacific Northwest Bell Telephone Company. They have the ability to supply the needed line capacity for all development in the area as long as they are aware of the need well in advance. Impacts The proposed development would consist of 108 dwelling units. Assuming the average dwelling unit would require two lines, a cable unit capable of carrying 216 lines would be required. Mitigating Measures 1. All telephone lines shall be installed underground. 2. Installation of telephone lines shall be coordinated with installation of electrical lines. Unavoidable Adverse Impacts None. Water Existing Conditions The project is located near the boundary of the Water District #75 and City of Tukwila service areas. The project is actually in the Water District 75 service area but would be served from the City of Tukwila pressure reducing station on 53rd Avenue South as shown on the site utility plan. This would necessitate a service area agreement with the two, Districts or a deannexation from the Water District 75 area. Impacts The City's water distribution system would be extended to serve the site as shown on the site utility plan with proposed connections to the existing pressure reducing station at 53rd Avenue South, and fire hydrants spaced as required to provide adequate fire protection. The water system within the development would be designed by the proponent's engineer and constructed within the private road rights -of -way. It would be dedicated to the City, and an easement would be granted for access to maintain the system. The proposed system would connect to the pressure reducing station in 53rd Avenue South. This station connects to the existing Cedar River Pipeline #4. Static pressure at fire hydrant No. 112 which is located downstream and to the north of the pressure reducing station was recorded at 69 psi. According to the Tukwila Water Department (David Grage) the static pressure has been increased to approximately 85 psi since that reading was taken. Fire flow should not be a problem in this area according to the City of Tukwila Fire Department (Jim Hole) because the site and pressure reducing station are located so close to the large Cedar River pipe line, required fire flow would be approximately 2100 gpm (see appendix for calculations) based on the site plan and building type. The proposed on —site system would comply with City of Tukwila fire flow and hydrant— spacing requirements, as well as with the requirements of the Washington State Department of Social and Health Services. According to Washington Survey and Rating Bureau criteria, approximately 2100 gpm (see appendix for calculations) is the required fire flow for multi — family developments of this type. The proposed system would meet the minimum criteria. Projected domestic water usage for the site should not exceed 0.04 mgd on a peak day (see appendix for calculations). As mentioned above, a service area agreement between the City of Tukwila and Water District 75 or deannexation from Water District 75 is required to serve the project from the City of Tukwila water system. Mrtieaeioe Measure, Installation of water restrictive fixtures and devices such as flow restrictors in new dwelling units (at the discretion of the builder) could reduce water consumption, if such measures are determined to be necessary or desirable. Unavoidable Adverse Impacts Short —term impact on vehicular travel at South 158th Street /53rd Avenue South if trending is required within the R.O.W. or across the road. During actual connection of the system, water service in the area could be interrupted for brief periods of time. Sewer Eris -tine- Conditions The site would be served by Val Vue sewer district. There is an existing 12 inch cast iron sewage main which runs through the site as shown on the utility site plan. The line connects to Metro at the Val Vue connection. Sewage from the site would be treated at the Renton Sewage Treatment Plant and would be transmitted to the plant via the Interurban Pump Station, Freeway interceptor and Tukwila Interceptor. The proposed project is within Metro's Renton Treatment Plant service area. Metro has prepared a facilities plan for the Renton system with a grant from DOE and EPA, in part because the Renton Treatment plant has reached its "design" capacity and continued development is occurring within the service area. A final plan for the Renton service area was adopted by the Metro council in November 1981 and contains a recommended program for upgrading the Renton system so that water quality and health will continue to be protected. The plan calls for these improvements to be on line in the summer of 1986. Imp-acts - The on —site sewage collection system would be designed by the proponent's engineer and would be installed as shown on the site utility plan. Six and eight inch lines would collect sewage throughout the project and connect into the existing Val Vue sewer line as shown. Projected sewage flow for the site should not exceed 0.05 mgd (including infiltration) on a peak day (see appendix for calculations). Portions of the existing 12 inch cast iron main .would be underneath proposed future building locations. The existing 12 inch line could be cased in a larger carrier pipe where it is underneath these proposed buildings to provide for future maintenance. The development will result in increased sewage flows. As stated above, 81 EXISTING STORM SYSTEM & EASEMENT It / ,y/ 1 / EXISTING STORM CONTROL MH / O VALLEY VIEW ESTATES /S / ,\\ SITE UTILITY PLAN \ EXISTING SEWER & EASEMEN?f LEGEND - (PROPOSED STORM LINE 00ovv PROPOSED WATER LItNE ® ®O ®PROPOSED SANITARY SEWER LINE the Renton Treatment Plant is currently treating more than design capacity but temporary measures are being taken which will accommodate flows. The plant will be upgraded in 1986 if present plans are implemented. Mitigating Measures If water use were reduced by residents implementing water - saving measures in their homes, the volume of sewage that would be discharged from the project area would be also reduced. Unavoidable Adverse Impaets Sewage generated by the development would contribute to above capacity discharges at the Renton Metro Sewage Treatment Plant. Stormwater Existing Conditions (Please refer to previous section covering Water). Solid Waste Existing Conditions The business and residences in the surrounding vicinity are currently served by Sea -Tac Disposal. Dumpsters and compactors can be rented from them. The solid waste is taken to the Ring County Transfer Station. Impacts The proposed development will increase demand for solid waste collection which can adequately be provided by Sea -Tac Disposal. M- ittgating Measures None. Unavoidable Adverse Impacts None. 89 Aesthetics Existing Conditions The site is currently open space. The site is visible from the valley floor and is part of the wooded valley wall between Interstate 5 and single family residences along the hillside. The proposed•site is situated just southwest of the 1-5/405 Interchange and directly west of the Southcenter Shopping Mall. A nearby residential area, McMicken Heights is located to the west of the site. Bordering the site on two sides are existing roads -- 53rd Avenue, S., to the west and Slade. Avenue to the South. The existing site presently consists of a heavily vegetated, moderately steep hillside that is densely vegetated with mature growth of mostly deciduous trees and underbrush. The existing view of the site from the west side of I -5 is of a very dense vegetative buffer adjacent to the freeway. The existing view from 53rd Avenue, South looking east to I -5 and Southcenter Shopping Mall is almost entirely blocked by the height and density of the existing vegetation on the proposed site. Impacts The appearance of the site will be transformed from open space to multi- family residential structures, parking areas and open space. The level of activity on the site will increase and the development will be visible from commuters along Slade Way and 53rd Road South. The development will not result in the blockage of any views from existing residences. The proposal would include an 18 building multiple family complex in a small portion of the existing portion of the existing wooded hillside west of I -5. VIEW FROM TUKWILA HILL LOOKING S.W. The proposed site would have its greatest view impact upon the areas to the east. This includes Southcenter Shopping Mall, Tukwila Hill and to a leser extent, traffic moving southbound on. 1-5. The multiple family complexes are situated high enough on the hill that existing vegetation nearest the freeway may be retained to minimize the visual change to the hillside. The view blockage from 53rd Avenue South would be minimal. Only two buildings on the extreme north and south sides of the site would have rooflines higher than the road grade. In both cases, they would be only 5 feet higher than road grade. All other buildings would be below the road grade. The view blockage from McMiken Heights, above 53rd Avenue South, looking east toward Southcenter Shopping Mall and 1-5 would be minimal. The proposed multi - family building rooflines are at least 45' below finished grade of the residential homes. Due to a bend in the freeway, views from motorists driving northbound on 1 -5 would be minimal. Building exteriors will be mostly natural wood and stucco. Class C composition shingles will be used on the roofs. Landscaping will be introduced in the parking areas and adjacent to the buildings to serve as buffers and soften the visual impact of the developed areas. Mitigating Measures 1. Existing vegetation will be maintained along the western portion of the site. 2. Ornamental vegetation shall include Sycamore, along Slade Way and along the parking lot. Vine, maple and flowering cherry would be interspersed among the buildings. Other plant materials would include photinia, rhododendron, mahonia, vibrurnum Davidi, ivy and lawn. LANDSCAPED BUFFER SECTION 1 PARKING LANDSCAPED BUFFER 53rd. AVE. O m m D z v v 0 0 0 D --1 m cn SECTION 2 Archaeoiogieal}fltstorical Existing Conditions There are no known historical sites or archaeological resources that would require physical preservation in the immediate area of the site. Impacts - The potential of archaeological resources existing on the site is remote. However, proposed mitigating measures are considered adequate to eliminate any potential impacts. Mitigating Measures In the event that cultural materials are disclosed during construction, work in the immediate area would be discontinued and the Office of Archaeology and Historic Preservation would be notified. Unavoidable Adverse Impacts None. 91 HUMAN HEALTH Exist-int Oonditions The human response to noise has been documented by the Environmental Protection Agency. Continuous noise at high decibels is not only irritating, but can cause damage to the hearing mechanism and otherwise impair both physical and mental health. Prolonged noise exceeding 80 decibels (dBA) can result in hearing loss. Noise in excess of 55 dBA can interfere with speech communication, and that above 35 dBA can disrupt sleep. Other physical effects from continuous, excessively loud noise levels are increases in blood pressure, and alterations in heart rate, which are usually temporary but may become chronic. It is improbable that environmental noise itself causes mental illness; however, the continual exposure to noise of a person already suffering in a depressed state may promote stress in that person, which does aggravate the condition of mental illness. Impacts The residents to the west and south of the subject site would be the most sensitive receptors of the construction noise generated from project development. those pag Depending on the position of the noise source in relation to omes, noise levels would approximate those shown on Table of this document. It is anticipated, however, that noise levels generated from construction would be attenuated to some degree by distance, even during the initial phase of construction. Therefore, although construction noise could be a source of annoyance and irritation to area residents, it is not expected to cause significant mental or physical - damage to them. Mitigating Measures Refer to the Mitigating Measures under "Noise ". Unavoidable Adverse Impacts Short —term annoyance and irritation to area residents during construction. 92. IV Unavoidable Adverse Impacts o Alteration of topography in order to minimize potential slope movement. o Short term odors during construction. o Removal of all natural vegetation from approximately 68 percent of the site. o Removal of vegetation will result in the loss of animal habitat. Most species that currently utilize the area proposed for grading and development will be eliminated. Urban tolerant species will replace those species which are not. o The project would result in moderate unavoidable noise impacts to residents of the development because of the freeway noise which exists at the site. Construction activities would cause temporary noise impacts at the closest adjoining residences. o Consumption of building materials and energy. o Potential spillover onto 53rd Avenue South, Klickitat Drive or Slade Way due to possible social activity. o Traffic accidents may be expected to increase in some proportion to the increase in traffic volumes on streets surrounding the proposed development. o Increased demand for fire service. o Increased demand for police service. o Increased demand for neighborhood park area in the Crestview neigborhood by approximately nine percent. o Increased demand for long -term city maintenance. o Increased energy demand on the site in both the short and long - terms. o Short -term impacts on vehicular travel at South 158th Street /53rd Avenue South if trending is required within the R.O.W. or across the road. o Sewage generated by the development would contribute to above capacity discharges at the Renton Metro Sewage Treatment Plant. o Short -term annoyance and irritation to area residents during construction. V. SHORT TERM USE VS. LONG TERM PRODUCTIVITY The condominium development proposed for the site will be a long term use of the land. The buildings can be expected to remain for at least 50 years or the life of the buildings. The development would prevent short term use of the land for open space. However, because the site is conveniently • located near Interstate 5 and Interstate 405 and, due to the nearness of Southcenter Shopping Center and attractiveness of view property, eventual development of the property is likely to occur whether or not this proposed project is implemented. Realization of the project would result in economic benefits to private investors as well as short -term payroll for construction workers. These benefits are balanced against permanent loss of a portion of the wooded valley wall and the unavoidable adverse impacts described on page Deferring development would present some disadvantages. Development at some future time could face increased costs, because of inflation and the potential scarcity and increasing costs of building materials. Further, deferral of the project would not necessarily eliminate or alleviate the level of environmental impacts associated with this project. 94 VI. IRREVERSIBLE AND TRRETRIEVABLE GOMMLTMENf OF RESOURGBS Completion of the proposed action will result in the long -term commitment of the major portion of the 7.08 acre site for buildings, parking lot and landscaped areas, thereby precluding other uses for the site. Due to the longevity and maintenance of structural improvements, land once developed for the proposed uses seldom reverts to a lower economic use or to its natural state. Thus, the proposed development would essentially be an irreversible commitment of land resources. Natural resources that would be expended to construct the proposed development would include aluminum, steel, glass, wood, concrete, sand and gravel. Of these, wood is the only item that is a renewable resource. Some of the others are technically recyclable, but for all practical purposes, they would be irretrievably committeroposed development. Additional quantities of hydroelectric energy and fossil fuels would be required for space heating and lighting, and other energy needs, over the life of the project. Water consumption would increase. Energy is not a renewable resource; as such, its use for the proposal would prevent it from being put to other uses that may or may not be more desirable environmentally. Likewise, implementation of the proposal would require a commitment of labor and financial resources which could potentially be used for different purposes. Additional long -term commitment of public water supply, sanitary sewer capacity, solid waste disposal capacity, communication services and police and fire protection services would be required to maintain the development. However, these services are presently utilized and available to the site and the demand for them will be within the norm for any similar commercial development. 95 vu ALTERNATIVES TO THE PROPOSAL 1. No Development: Des.cript ion The site would remain in its undeveloped state and continue to serve as a part of the wooded hillside. Impact All adverse environmental impacts of the project would be eliminated. Feasibility The proponent desires to construct a multiple family development, which would not be met by this alternative. Although the site is currently undeveloped, it is highly improbable the site would remain undeveloped unless it is acquired by the City of Tukwila or King County for park use or greenbelt. It is not shown as a park or greenbelt in the Comprehensive Plan nor designated for acquisition in the City's Capital Improvement Program. 2. Development to Single Family: Description Up to 21 detached dwelling units could be constructed under this zone. Impacts- Overall, implementation of the single family density alternative would impact all elements of both the physical and human environments to a lesser degree than the proposed action. Traffic generation would be approximately 23 percent of the proposed action. Residential population would also be only 20 percent of that of the proposal. Feasibility Construction of a lower density single family alternative would not meet the objectives of the proponent of providing a multiple family residential development. Further, the necessary site improvements would in all probability, price the single family homes higher than their market value. 3. Development of More Intensive Use Description Under the R -4 District - Low Apartments and RMH District - Multiple Residence High Density, the following uses are permitted: R -4 District: Apartment houses, row houses, boarding houses, childrens boarding homes, lodging houses, clinics for people only, convalescent homes, nursing homes, convents, private clubs or fraternal orders, schools other than those permitted in the R -2 District. RMH District: Any use permitted in the RMH District, Apartment House, hotels; offices and clinics provided they do not exceed the first two stories. Based on the listed permitted uses, a development scenario could include the following: Density Use Desiznation Acres Yield Convalescent Home 2.52 @ 300 SF /patient 350 patients or lot area or Apartment Building 2.52 @ 30 DU /Ac. 75 DU's. and and Office (2 story) 2.86 @ 40% Site Coverage 50,000 s.f. Impacts Overall, implementation of this alternative would impact both the physical and human environments to a greater degree than that of the proposed action. Open space would be significantly reduced. Traffic generation would be roughly double that of the proposal. Feasibility This scenario would not meet the proponent's objective. 97 Lower Density Multiple Family Development Description: Five fewer buildings would be constructed providing a total of 13 buildings with a total of 78 dwelling units. Impact Adverse environmental impacts would be less than those created by the proposed action. The parking lot would proportionately be reduced. Traffic generation would be reduced by approximately 28 percent. The site could support slightly more than one -half acre more of undeveloped open space than under the proposed action. Feasibility Construction of a lower density multiple family development would not meet the proponent's objective. Due to higher site improvement costs and infrastructure cost per dwelling unit compared to the proposed action, condominium prices would be higher than the proposed action and in all probability, price them higher than their market value. 98 APPENDIX A Zoning Regulations — Permitted Uses Chapter 18:12- R-1 District - One Family Dwellings 18:1:819 Additional classifications. The R -1 district is further subdivided into districts differing only in the requirements of lot area per family as follows: R -1 - 7.2 R -1 9.6 R -1 - 12.0 (Ord. 251 4 -1 (part), 1957). Minimum Lot Size Per Dwelling Unit 7,200 square feet 9,600 square feet 12,000 square feet 18:12-:G2G Use reguleeions -- Generally. In the R -1 district, no building or land shall be used and no building shall be erected, altered, or enlarged, which is arranged, intended or designed for other than one of the uses in this chapter, except as otherwise provided in Chapters 18.64 and 18.66. (Ord. 251 4 -1 (part), 1957). 18:13-8 Use regulations -- with special restrictions. Uses without special restrictions shall be as follows: 1. One family dwellings; 2. Publicly owned parks and recreational areas; 3. Golf club houses, including courses, but not including miniature golf courses and driving ranges; 4. Agriculture; 5. Greenhouses, nurseries and truck gardening, propogating and cultivating only, of plants, upon approval of the planning commission, after a public hearing; provided no retail or wholesale business shall be carried on upon the premises so used; and provided further, that no obnoxious fertilizer is stored upon the premises and no obnoxious soil or fertilizer renovation is carried on upon the premises. (Ord. 252 4 -1 (part), 1957). 18.18:018 Use Regulations. In the R -4 district, no building or land shall be used and no building shall be erected, altered, or enlarged, which is arranged, intended or designed for other than one of the following uses, except as otherwise provided in Chapters 18.32 and 18.66; 1. Any use permitted in R -3 district. The specific conditions governing the locations of uses enumerated in Section 18.12.040 of R -1 uses do not apply.. 2. Apartment houses, row houses, and converted dwellings; 3. Boarding houses and children's boarding homes for more than four children; 4. Lodging houses. For the purpose of computing the number of lodgers allowed, a minimum of three hundred square feet of lot area shall be provided for each lodger. 5. Clinics for people only, and offices of surgeons, physicians (including osteopaths and chiropractors) or dentists, when the property is in single ownership, and adjoins or abuts a business or industrial district within the same block, and borders or fronts on a street which is a continuation of a street in .the business or industrial zone, bordering the same block. This use .will be permitted after a public hearing and approval by the planning commission. The commission shall determine that such use will not materially injure the appropriate use of neighboring property. Off street parking shall be provided on the premises as required for office buildings in Chapter 18.56, plus an additional twenty —five percent of that requirement. The commission shall make such restrictions and safeguards as necessary, in its opinion, to keep the property in harmony with the permitted residential uses in this district. 6. Convalescent homes, nursing or old folks' homes, other than for mental patients, alcoholics, or persons having contagious diseases. For the purpose of computing the number of patients or guests allowed, a minimum of three hundred square feet of lot area shall be provided for each patient or guest. 7. Convents, private clubs or fraternal orders, including fraternity or sorority houses, except clubs, the chief activities of which are services, customarily carried on as a business. 8. Office buildings, to be used exclusively for the administrative functions of a single organization, or by a single professional organization or society, after public notice and hearing and approval by the planning commission, when the property is in single ownership, and adjoins or abuts a business or industrial district within the same block and borders or fronts upon a street which is the continuation of a street in the business or industrial zone bordering the same block; Provided that the occupancy has only limited contact with the general public; and provided that no merchandise is handled or merchandising services are rendered on the premises. The commission shall determine that there is ample off street parking space on the property commensurate with the proposed use, using as a. minimum the amount required for office buildings in Chapter 18.56, plus twenty -five percent additional. The commission shall also determine that this use will not affect adversely the present character or future development of the surrounding residential community. The commission may place any additional restrictions or safeguards necessary, in its opinion, to preserve the meaning and intent of this title. Only one sign or nameplate, permanently attached to the building, not over nine square feet in size, and giving the name only of the organization, shall be permitted. 9. Schools, other than those permitted in R -1, and not otherwise classified, after public notice and hearing and approval by the planning commission. 10. Accessory uses customarily incident to the above uses, and located on the same lot therewith, not involving the conduct of a business or industry as follows: a. Any window or other display or sign shall comply with the regulations for such accessory uses in district R -1, except that in this district an unilluminated sign, advertising lodging and /or board, shall be allowed, which sign shall not exceed eighty square inches in size. b. Home occupations as defined in Section 18.06.420 shall be allowed in this district but in this district an unilluminated sign, attached to or within the building, not to exceed eighty square inches, carrying the name and occupation, may be allowed. c. All other limitations governing accessory uses in R -1 district shall apply to R -4 district. (Ord. 251 4 -4 (part), 1957). }81 2 ;GIG Use Reatriations -. In the RMH district no building or land shall be used and no building shall be erected, altered or enlarged, which is arranged, intended or designed for other than one of the following uses, except as otherwise provided in Chapters 18.32 and 18.66. 1. Any use permitted in the R -4 district, as specified and regulated in Section 18.18.010; 2. Apartment house; 3. Hotels; 4. Offices and clinics of physicians, surgeons, dentists, physical therapists, architects, engineers, lawyers, when such offices occupy no more than the first two stories of the building or a cellar of a building and the story next above. (Ord. 298 1 (part), 1960; Ord. 251 4 -4A (part), 1957). APPENDIX B Noise Impact Analysis VALLEY VIEW ESTATES NOISE .IMPACT ANALYSIS Prepared for STEPAN & ASSOCIATES, INC. 930 S. 336th Street, Suite A Federal Way, Washington 98003 Submitted by TOWNE, RICHARDS & CHAUDIERE, INC.' 105 N.E. 56th Street Seattle, Washington 98105 JANUARY 1984 • CONTENTS INTRODUCTION 1 EXISTING NOISE LEVELS 1 Summary of Existing Noise Levels 1 Noise Descriptors and Criteria 1 Existing Measured Noise 4 IMPACTS 9 Summary of Potential Noise Impacts 9 Interior Noise Levels On -Site 9 Exterior Noise Levels On -Site 10 Noise Level Changes Off -Site 11 Construction Noise 12 MITIGATING MEASURES 13 UNAVOIDABLE NOISE IMPACTS 14 TOWNE, RICHARDS 8 CHAUDIERE, INC. Consultants in Sound & Vibration INTRODUCTION The following report is a Draft EIS noise impact analysis for the proposed Palley View Estates multi - family residential development in the McMicken Heights area of Tukwila. The report describes design solutions which can be employed in the control of interior noise levels, especially as influenced by proximity to the I -5 corridor, as well as off -site noise impacts produced by the project. The proposed project is to build 18 buildings containing 108 units on a site located in the southwest quadrant of the interchange of I -5 and SR 518. Further descriptions of the project are contained elsewhere in the Draft EIS. EXISTING NOISE LEVELS Summary of Existing Noise Levels Traffic on I -5 is the predominant source of noise affecting the site and adjoining properties. Existing day -night sound levels on the site are 65 to 72 dBA, and maximum nighttime sound levels are about 77 dBA. Architectural noise mitigation is generally required to prevent significant impacts at sites where exterior day -night sound levels exceed 65 dBA. Day -night sound levels at the closest residential properties west of the site are 63 to 65 dBA, and maximum nighttime levels are about 72 dBA. These properties experience some noise impacts from I -5 traffic, although day -night sound levels below 65 dBA are considered acceptable according to EPA and HUD criteria. Noise Descriptors and Criteria Noise is measured as A- weighted sound level in decibels, dBA. The decibel scale is related to human perception of loudness, with approximately a doubling of subjective loudness for each 10 dBA increase in sound level, which is a tenfold increase in sound energy and intensity. A 5 dBA increase in sound level is considered a significant change. A doubling of sound energy, such as would be produced by a doubling of the number of noise 1 TOWNS, RICHARDS & CHAUDIERE, INC. Consultants in Sound & Vibration sources present, produces a noticeable 3 dBA increase in sound level. Noise increases of 1 to 2 dBA are barely noticeable, and increases of less than 1 dBA are generally not noticeable. Combined sound levels from multiple sources are calculated logarithmically. For example, noise sources of 60 dBA and 62 dBA combine to produce 64 dBA, not 122 dBA. The sound from point noise sources is attenuated (reduced) due to distance by 6 dBA per doubling of distance from "point" noise sources, and by 3 to 4.5 dBA per doubling of distance from "line" sources such as street or highway traffic. Sound is also attenuated by ground absorption, absorption by trees and other vegetation (usually only significant over distances of several hundred feet or more), and by barriers, which may be either topographic or man -made. At distances of thousands of feet or more, atmospheric absorption of sound also becomes significant. Sound levels usually fluctuate over time. Noise descriptors and criteria therefore must take into account the fluctuating nature of sound. The following A- weighted sound level descriptors are commonly used: o Average (or "equivalent ") sound level, Leq, is the energy average sound level of the fluctuating noise over a given time period. o Day -night sound level, Ldn, is the equivalent sound level over 24 hours with a 10 dBA penalty applied to nighttime noise, and is used by EPA and other federal agencies. Maximum sound level, Lmax' is the highest sound level during a given time period. The U.S. Environmental Protection Agency (EPA) Region X Noise Guidelines for Environmental Impact Statements (January 1975) suggest the following qualitative considerations for exterior day -night sound levels affecting residential activity: TOWNE, RICHARDS & CHAUDIERE. INC. 2 Consultants in Sound & Vibration Ldn Below 55 dBA Qualitative considerations applicable to individual actions Levels are generally acceptable: no noise impact is generally associated with these levels. 55 to 65 dBA Adverse noise impacts exist: lowest noise level possible should be strived for. 65 to 70 dBA Significant adverse noise impacts exist: allowable only in unusual cases where lower levels are clearly demonstrated not to be possible. Over 70 dBA Levels have unacceptable public health and welfare impacts. The guidelines consider actions that increase noise levels by 0 to 5 dBA to have slight impact, 5 to 10 dBA significant impact, and over 10 dBA very serious impact. Other EPA documents indicate that interior Ldn should be 45 dBA or less in.order to protect health and welfare with an adequate margin of safety. The U.S. Department of Housing and Urban Development (HUD) Site Acceptability Standards for noise contained in Title 24 CFR Part 51 are as follows: 3 TOWNE, RICHARDS 8 CHAUDIERE, INC. Consultants in Sound & Vibration Ldn Site Acceptability Standard Not exceeding 65 dBA Acceptable Above 65 dBA but not Normally Unacceptable exceeding 75 dBA Above 75 dBA Unacceptable The standards require 5 dBA additional sound attenuation (reduction) for housing constructed on sites above 65 dBA but not exceeding 70 dBA, and 10 dBA additional attenuation for sites above 70 dBA but not exceeding 75 dBA. To prevent the probability of sleep interference from exceeding approximately 50 percent, studies* indicate that interior maximum sound levels, Lmax, should be limited to about 50 dBA in. bedrooms. Existing Measured Noise Existing noise levels were measured between Thursday, October 20 and Tuesday, October 25, 1983 at four locations shown in Figure 1. The measurements consisted of full 24 hour noise monitoring at three locations and 19 hours noise monitoring at the fourth location, where adverse weather curtailed the measurement. A Digital Acoustics DA607P noise monitoring system was used for the measurements. Results of the measurements in hourly Leq, hourly Lax, and Ldn are shown in Figures 2 and 3.. Locations 1 and 2 are on the site, and Locations 3 and 4 are off -site residences immediately west of the site which have views across the site toward I -5. The following is a summary of the measured day -night sound levels, Ldn, and nighttime maximum sound levels, Lmax: *Miller, J.D., Effects of noise on people, Journal of the Acoustical Society of America, 56, 3, September 1974. 4 TOWNE, RICHARDS & CHAUDIERE, INC. Consultants in Sound & Vibration Existing exterior noise levels, dBA Location Description Ldn Night Lmax 1 SE part of site 72 77 2 NE part of site 65 (68 *) 77 3 Residence W of site 65 72 4 Residence SW of site 63 72 *Location 2 had partial topographic shielding of highway noise, which is estimated to have reduced Ldn by about 3 dBA compared to noise levels at a future upper story elevation. Existing noise levels on the site and adjoining properties are dominated by I -5 freeway traffic noise. Day -night sound levels (Ldn) on the site are above 65 dBA, indicating a need for architectural noise mitigation. Ldn at the closest properties to the east are 65 dBA or less, indicating that there are some noise impacts from I -5 traffic, although Ldn up to 65 dBA are acceptable according to the HUD and EPA criteria. The existing noise levels are typical of properties near freeway corridors, and are about 10 to 15 dBA higher than the level of Ldn 55 dBA which is considered desirable for residential areas according to EPA. 5 TOWNE, RICHARDS8 CHAUDIERE, INC. Consultants in Sound & Vibration SCALE 0 CO 200 5,20 MOO 600 1000 FEEr Figure 1. Existing Noise Measurement Locations TOWNE, RICHARDS & CHAUDIERE, INC. Consultants in Sound & Vibration • 24 HOUR AMBIENT NOISE LEVELS AT LOCATION 1 VALLEY VIEW ESTATES • 24 HOUR AMBIENT NOISE LEVELS AT LOCATION 3 VALLEY..V.IEW _ESTATES _ Tf . ; • 1 • .. • 1 :• . .:. : :1'..: "" T .. .1 , . : . '; •':. 1::.: :: i::::: A. - • : m 1 : i • t • ; f: %. 1 , • 1 : ,...,:.: :• . ti, ..,_ -,-s- .4.., _I • LU ' --I , .. 1-7-• CI Z . 60P- m . . . . • : ! . • \Ij ,f .;,. , ..i_T_L...r...,:::,.:::. : ./1: .T.i .. i .. •:, , 17! ---- 7 ...„ ,N ! : • ! ..„, : .• 1% I . • . . , .......77.1.....■ '... , ... ■ I j i. . r : ! . ' . ' :. i 1 1 . • i i.. l''.. . ! I i . • • !: !' : • I. • ... . ... • • , • . • • ; • • - 30-- r 21}: -1 • 7 8 19 • 20 41 42 23 1110-N 1 2 3 . 4. 5 7 8 9 10 1 NOON 13 . 14 15 . 16 . -10/20/93 -".- TIME AT ENO OF HOUR 1 • i• •I • ; . 24 HOUR AMBIENT NOISE LEVELS AT LOCATION 4 YALLEY..VIEW.ESTATES 1 • .:.. • • . . ; . . • T...... . . '... ..• .:- . •••,.. .,. ,., „: ..::+-..--• .--. • r . ----: 71. t. _H-1-7. i . :•;—, f — : I 1 • . , : • -1- I. .—' rl ' '-' - • -.'130--- -.'• -._1.-... „:. !.:. . r-' ,-..... 1- s'.. , 1 : -...._ t - -. . • . . ,.. :.,.. . T I- : , ,,..... ; -; •- !-„--!:..... .! ... . : 1., ,- :•-, i . • I 4,- f--:. -LI - .7_1 .- :- - - 1 1- ' ' "-i. '- *1 • • ; ' • • '• CO ... • . • o■ , ■ • i .., .., ....• ■ : I • ! ■ ._ i • _....i ,] r -.f - ..1-4 ; \-• . ; ; -r•-•.-7-----1-----1---4--. ' 41° A . •....{‘' . ' .; I i., - - ': :. : - 4..--.-14- .1 : : ..:* . ' , - % -I- -,.. 1 ,....'i, ■ i :,r,, . • ; • 7 --'•--- : t 4..i - - ...... - ..-., .....!......i---:-.1...,:.......-r.-1--....-......,_1t..1...c__,_... ; ....„‘F----- i.,;.- ......_.,......-...... 1......... .-.: . . . >. .. . .. A ....:. .... 1.--.----i.„--- i ----I; ' ---T• ----'!-•-- •---r-4"---7 , 1.. .r , , f I c - I - : I ; % it . i, . 1 • i LU ' " i I : • ,. ,.:.,• 1 • ,4,.. e1 t- - -.:' • - • '' l''-'''"!--T7'.•-1-'"P'. .....1,77...:77.7...:L.I.:...A.11,1.M.Jialui,—,71:7 • . - •, i . , i, • •.• .. s!.....,.i.i. , . . -.1_,— • i • i • i - .1 ::.• .si::..:•_1:::•:: . .c.... .; .. . . ... ., L .• :..• LLI 3e • ;• • • . . • ; • - • r•--1 - ! • - • ; - • • r--: —f— • : 1 i• : ..... I 20. ijil 3 4 5 16 17 18 9 20 21 22 23 1110-14 1 2 3 5 6 7 8 9 10/24/83 . . TIME AT ENO OF HOUR ; • i i Figure 3 TOWNE, RICHARDS & CHAUDIERE, INC. 10 11 NOON 10/25/51.; Consultants in Sound & Vibration IMPACTS Summary of Potential Noise Impacts Exterior day -night sound levels on the site are in a range above 65 dBA where significant impacts on interior and exterior uses could occur unless mitigation is provided. An exterior -to- interior attenuation (noise reduction) of 30 dBA, about 5 dBA better than conventional construction, would provide generally acceptable interior noise levels according to EPA and sleep interference criteria. In addition, forced -air ventilation would be desirable so that windows would not have to be open for ventilation. Some exterior spaces could be shielded from freeway noise to prevent speech interference and annoyance, especially the proposed children's area. Physical site modifications and traffic generated by the project would result in negligible noise changes at off-site properties. Construction noise would largely be masked by the existing freeway noise. Interior Noise Levels On -Site Exterior noise levels at the proposed building locations were described in the Existing Noise Levels section. On the southeast part of the site (measurement Location 1), exterior day -night sound level, Ldn, was 72 dBA. On the northeast part of the site (measurement Location 2), exterior Ldn was 65 dBA at a first story elevation and about 68 dBA at higher elevations. Nighttime maximum sound levels, Lmax, were 77 dBA at both locations. On the southern half of the site, exterior Ldn is in the range 70 to 75 dBA were 10 dBA of additional exterior -to- interior sound attenuation would be required by the HUD standards cited previously if this were a HUD project. On the northern half of the site, exterior Ldn is in the range 65 to 70 dBA where 5 dBA of additional exterior -to- interior sound attenuation would be required by the HUD standards. The HUD regional office considers the attenuation of conventional Northwest housing to be 25 dBA. Construction to meet the HUD standards must therefore provide exterior -to- interior attenuation of 35 dBA on the southern half of the site TOWNE, RICHARDS & CHAUDIERE, INC. Consultants in Sound do Vibration A on the if. A comparison of interior sound levels with and 30 d6 o t e northern ha p t and without added attenuation, and with open windows, is shown in the fol 1 owi ng table. Interior sound levels, dBA Construction Part of site Ldn Night Lmax according to the criteria discussed previously. It is therefore recommended that noise mitigation for exterior spaces be considered, especially for the proposed children's area on the northeast part of the site. Possible mitigation is discussed in the Mitigating Measures section. TOWNE. RICHARDS& CHAUDIERE, INC. 10 Consultants in Sound & Vibration Noise Level Changes Off -Site The proposed project is expected to cause negligible long -term noise changes at off -site properties. The site currently has narrow -trunk alder growth which provides slight excess attenuation (reduction) of I -5 freeway noise for properties west of the site. The trees are currently bare, and are estimated to provide at most 3 dBA of excess attenuation per 100 meters,* or about 2 to 3 dBA excess attenuation for properties west of the site. In summer, the excess attenuation would be slightly higher because of foliage. Construction of buildings on the site would provide partial shielding of views of the freeway, reducing freeway noise levels at properties to the west by about 3 dBA due to an approximate 50 percent shielding. This attenuation by the buildings would offset the loss of attenuation resulting from removal of existing trees on the site. The project would result in negligible noise increases along local streets due to increased traffic. It should be noted that highway traffic noise from I -5 and SR 518 is predominant near the site, and that noise from the low to moderate traffic volumes on local streets is insignificant by comparison. Day -night sound levels, Ldn, from street traffic were computed using estimated 1987 daily traffic volumes with and without the proposed project as described in the Traffic Impact Analysis. The FHWA -RD -77 -108 noise prediction methodology was used. It was assumed that 10 percent of traffic occurs during nighttime hours of 10 p.m. to 7 a.m., and that traffic speed is about 30 mph. The noise prediction was for a setback of 50 feet from street traffic. Where appropriate, the street traffic noise was combined with the noise from I -5. *Beranek, L.L., Noise and Vibration Control, McGraw -Hill, New York, N.Y., 1971. 11 TOWNE, RICHARDS 8 CHAUDIERE, INC. Consultants in Sound & Vibration 1987 day -night sound levels, dBA Street noise Combined noise Street Freeway noise without /with project without /with project 53rd Ave. S. 65 55/56 66/66 north of site S. 160th St. 54/55 54/55 west of site Slade Way and 54th Ave. S. 72 44/45 72/72 south of site The largest noise increase, 1 dBA, would occur along S. 160th Street west of the site. This amount of noise increase would not be noticeable. Noise increases on other more distant streets would also be negligible (less than 1 dBA increase). Construction Noise There would be temporary noise impacts during construction of the project. These impacts would be minimized by the fact that most construction would occur along the eastern part of the site, away from residences, and also because the existing freeway noise would mask much of the construction noise. The highest construction noise levels would be received at a residence at the corner of Slade Way and 54th Avenue S., about 100 feet from the southernmost proposed building. At this distance, construction noise levels could average between 59 and 82 dBA, depending on the activity and phase of construction, according to EPA data. Existing daytime noise levels from I -5 average about 70 dBA in this area, as shown in Figure 2. It is therefore expected that the noisiest activities could exceed the existing traffic noise by up to 12 dBA, but that the typical construction noise would be close to the levels of existing noise. 12 TOWNE, RICHARDS & CHAUDIERE, INC. Consultants in Sound do Vibration The closest residences west of the site would be about 200 feet or more from construction activity, and would receive estimated construction noise levels between 53 and 76 dBA, again depending on the activity and phase of construction. Typical construction noise levels would also be similar to the existing freeway noise levels (about 60 to 65 dBA) at these locations. Construction could not occur before 7 a.m. on weekdays and 9 a.m. on weekends, or after 10 p.m., because of stringent State of Washington (WAC Chapter 173 -60) noise code restrictions on construction in residential areas during nighttime hours. MITIGATING MEASURES The following measures could be used to mitigate the noise impacts of the project: o An exterior -to- interior sound attenuation of 30 dBA, about 5 dBA better than conventional construction, would provide generally acceptable interior noise levels according to the criteria cited. The additional 5 dBA attenuation can be achieved by using windows and glass doors having at least 5 dB better acoustical performance than conventional thermal insulated windows, as measured using sound transmission class (STC) rating or sound transmission loss curves. The windows and glass doors should have a minimum overall outside -to- inside thickness of 1 ", which can be achieved by using either double or triple glazing, since the middle glazing of a triple glazed window does not contribute significantly to acoustical performance. Each glazing should have a minimum thickness of 3/16 ", and the outside and inside glazings should have different thicknesses in order to avoid acoustic coupling. For example, a window can consist of 1/4" glass, 9/16" air space, and 3/16" glass. The glass should be set in resilient gaskets. Operable windows and exterior doors (including glass doors) should be hinged rather than sliding, and should have resilient seals. Exterior doors should have automatic threshold drops or compressible neoprene threshold seals. These measures apply to north, south, and east facing windows and exterior doors. 13 TOWNE, RICHARDS & CHAUDIERE, INC. Consultants in Sound & Vibration o East facing decks can be glass- enclosed, to effectively provide double windows between the outside and inside of the residential unit. If this construction is used, the 1" thickness is not necessary for the exterior or interior windows of the deck area. o Forced -air ventilation could be provided, especially to bedrooms, so that windows would not have to be opened for ventilation. Open windows provide only about 10 to 15 dBA outside -to- inside noise attenuation. o Noise levels could be reduced for some exterior spaces by use of barriers. For example, an eight foot high solid continuous fence around the eastern half of the proposed children's area would reduce the average noise levels by about 10 dBA, to about 55 dBA or less, which is an acceptable level for preventing noise- induced speech interference and annoyance outdoors. The barrier would have the disadvantage of reducing views from this area, however. Noise levels on the outdoor decks could be reduced by about 5 dBA by using a solid barrier around the deck. The barrier should be high enough to block views of the freeway from a typical user location (presumably seated), but need not be so high that it blocks views of the valley and mountains to the east. Acoustic barriers may be constructed of wood with minimum thickness of 3/4 inch. Plywood, board - and - batten, or tongue- and - groove construction are acoustically acceptable. Barriers should have no gaps or openings, including the base. o Construction should not occur before 7 a.m. on weekdays and 9 a.m. on weekends, or after 10 p.m., to prevent State noise code violations. In addition, any diesel or gasoline powered equipment used at the site could be required to have a proper muffler that is in good condition. UNAVOIDABLE NOISE IMPACTS The project would result in moderate unavoidable noise impacts to residents of the development because of the freeway noise which exists at the site. Construction activities would cause temporary noise impacts at the closest adjoining residences. TOWNE, RICHARDS 8 CHAUDIERE, INC. 14 Consultants in Sound & Vibration Appendix C Geotechnical and Hydrological Studies REPORT GEOTECHNICAL AND HYDROLOGICAL STUDIES PROPOSED VALLEY VIEW ESTATES SLATE WAY AND 53RD AVENUE SOUTH TUKWILA, WASHINGTON FOR DR. H. M. ALLENBACH T A B L E O F C O N T ENT S INTRODUCTION SCOPE REVIEW OF SITE HISTORY SITE CONDITIONS SUBSURFACE CONDITIONS GEOHYDROLOGICAL AND SURFACE WATER CONDITIONS Page No. 1 1 3 4 6 7 CONCLUSIONS AND RECOMMENDATIONS 7 GENERAL 7 EVALUATION OF 1-5 DRAIN SYSTEM 9 STABILITY 10 SITE GRADING, INTERCEPTOR TRENCH AND SURFACE DRAINAGE 10 STRUCTURAL FILLS AND PAVING 12 RETAINING STRUCTURES 12 FOUNDATION DESIGN 13 MONITORING 15 USE OF THIS REPORT LIST OF FIGURES 15 Figure No. SITE PLAN 1 HORIZONTAL DRAIN AND WELL SYSTEM 2 CROSS SECTION A -A1 APPENDIX 3 Page No. APPENDIX A A -1 FIELD EXPLORATIONS AND LABORATORY TESTING A -1 LABORATORY TESTING A -1 APPENDIX B B -1 PIEZOMETRIC LEVELS B -1 INCLINOMETER DATA B -1 Appendix Plates UNIFIED SOIL CLASSIFICATION SYSTEM AND KEY TO SAMPLE DATA LOGS OF EXPLORATION Plate No. A -1 A -2 thru A -19 GeoEngineers Incorporated REPORT GEOTECHNICAL AND HYDROLOGICAL STUDIES PROPOSED VALLEY VIEW ESTATES SLADE WAY AND 53RD AVENUE SOUTH TUKWILA, WASHINGTON FOR DR. H. M. ALLENBACH INTRODUCTION This report presents the results of our geotechnical and hydrological studies of the site proposed for construction of Valley View Estates, a condominium devel- opment. The site is located adjacent to the west right -of -way for Interstate Highway No. 5 and is bounded on the south by Slade Way and on the west by Slade Way and 53rd Avenue South, as shown on the Site Plan, Figure 1. The proposed development includes construction of 18 six -unit condominium structures together with associated roadways, parking areas and utilities. The units will be stepped into the hillside, requiring varying depths of cut. Some cutting and filling will also be required to construct the roadways and parking areas as well as to establish reasonable grades around the various buildings. Wood frame construction and consequently relatively light foundation loads are expected. The proposed condominium property is located within a very large, prehis- toric, landslide zone.. Also, a substantial portion of property was involved in the landslide which occurred in 1960, as the result of excavation of borrow material which was used for fill in the Andover Industrial Park. Since con- struction of Interstate Highway No. 5, the stability of this property and adja- cent properties on the southwest portion of the interchange of the freeway with State Route 405 have been improved by the remedial drainage measures which were installed by the Washington State Department of Transportation during freeway con- struction to the extent that no evidence of deep seated movement was noted during our site examinations. These facilities include systems of horizontal drains and vertical wells, a number of which exist along the eastern limits of this property. SCOPE The scope of services for these studies was developed following a meeting on August 2, 1983 of the various parties involved in assembling information for GeoEngineers Incorporated the Environmental Impact Statement for this project. The scope of services reflects our assessment of the extent of study which we feel is appropriate for this project, based on studies made for the 1960 landslide by members of our staff and a review of existing surficial site conditions by our firm in 1982. Our proposal describing the services to be provided was submitted in a letter dated August 9, 1983. Authorization to proceed was transmitted to us by Mr. William Snell in September. The purpose of these services is twofold: 1) to develop pertinent informa- tion on soil and ground water conditions for inclusion in the Environmental Impact Statement, and 2) to development further design criteria, as appropriate, for the geotechnical aspects of the project. Our scope of services includes: 1. Exploring subsurface soil and ground water conditions by drilling a series of test borings from which representative soil samples were obtained and in which piezometers were installed to monitor ground water conditions at appropriate levels. 2. Evaluating pertinent physical and engineering characteristics of soils from the results of laboratory tests. 3. Reviewing any information that is available from the Washington State Department of Transportation on the subsurface drainage system which was installed in the site area during construction of Interstate High- way 5. 4. Defining, to the extent possible, past landslide history of the imme- diate area. 5. Evaluating the overall stability of the project site for present geo- technical and hydrological conditions. 6. Evaluating pertinent design criteria for the geotechnical elements of the project, including stability of cut and fill slopes, design criteria for shallow foundations, retaining structure design criteria, earthwork procedures, and site drainage requirements. In addition, our scope of services was expanded to include the installation of a slope indicator casing and obtaining an initial set of readings in Boring F. This installation has been made in an area of past sliding history, but lies above the area of planned development so that information from subsequent readings will provide a means of monitoring any movements of the hillside in the area be- tween Slade Way and the planned condominium units. - 2 - GeoEngineers Incorporated ' REVIEW OF SITE HISTORY The review of the site history included reviewing the files of the Washington State Department of Transportation in Olympia and soils reports pertaining to the site. The soils reports that were reviewed are as follows: - "Report of Stability Investigation, Borrow Area Slide, 54th Avenue South and South 162nd Street; Tukwila, Washington ", by Dames &'Moore,. December 1, 1960. - "Report of Soils Investigation, Earthslide, South 162nd Street Near 53rd Avenue South, Tukwila, Washington ", by Dames & Moore, June 27, 1961. - "Summary Report, Slope Stability Investigation, Tukwila Interchange (SRS) ", Shannon & Wilson, April 14, 1966. - "Summary Report, Soil Conditions and Earth Movements, Vicinity of the Tukwila Interchange ",.by Shannon & Wilson, June 21, 1968. - "Geotechnical Design Consultation, Proposed Condominium Development, Slade Way and 53rd Avenue South, Tukwila, Washington ", by GeoEngineers, Inc., May 3, 1982. The listed reports document a large earth slide that occurred at the site in 1960 as material was being excavated in a borrow area immediately downslope of the site. The extent of the slide is well documented in the 1960 and 1961 reports and is shown in Figure 2. The slide covered the southern two - thirds of the site as well as extending another 200 feet upslope of the western boundary of the site. Measurements during October 1960 reveal that the slide area was moving an average of 0.5 feet per day. The 1960 and 1961 reports concluded that.movement was occurring in a shear zone 25 to 40 feet below the ground surface through the central portion of the slide. In addition, the shear zone was considered to consist of a clayey mate- rial which is underlain by a deposit of waterbearing sand. The slide movement had resulted from the combined effect of excavation and the substantial hydro- static pressures existing in the waterbearing sand layer. The remedial measures considered were based on reducing hydrostatic pressure within the waterbearing sand layer which appeared to immediately underlie the failure surface. Deep wells as well as horizontal drains and drainage trenches were considered. A series of horizontal drains was installed together with some regrading of the borrow pit area. No records have been located to define the number or extent of these drains; however, it is the recollection of Mr. Jack K. Tuttle of our firm, who was involved in the studies at that time, that several horizontal drains 1 - 3 - GeoEngineers Incorporated were installed and that the major movements of the landslide were essentially arrested at that time. The subsequent earthwork in relation to construction of Interstate Highway No. 5 has apparently destroyed most of these horizontal drains. The 1966 and 1968 reports are related more to the overall stability of a larger portion of the hillside immediately west of the interchange prior to the construction of the interchange ramps and related roadways. At that time there had been considerable landslide activity not only at the project site but north and northwest along the hillside. Ten to twelve landslides of various dimensions were observed in these areas. The 1968 report shows several recent slide scarps at the project site. With one exception, all of these are less than 200 feet long and are aligned along the contour; however, one is approximately 700 feet long and is aligned approximately at 45 degrees to the contours in the northern third of the site. This scarp appears to be the :,orthern boundary of a large slide, possibly the 1960 -61 slide. The proposed remedial measures consisted of an extensive subsurface drainage system of vertical wells tied into horizontal drains and cylinder pile wall re- taining structures. These remedial measures were initiated by the State and were subsequently monitored and reported on by Shannon & Wilson. The piezometer records for pre- and post -drain installation are discussed later in this report. The 1966 report summarizes potential failure modes for the landsliding on the hillside and, like the 1960 and 1961 studies, concludes that the mode of failures at the project site is due to the presence of a clayey silt underlain by sands with artesian pressures. The report includes classification and aver- age strength values for the important materials in the hillside. These values were utilized in our studies. Some evidence of near - surface movement, mostly in the form of shallow creep and flow slides, was noted in our examination of the site prior to preparing our consultation report of May 3, 1982. A recent scarp was observed east of Slade Way. The scarp is about 200 feet long and varies from about 12 to 20 inches in height. The downslope extent of the slide appeared to be limited to the upper portion of the property in which no construction is planned. The slide was estimated to have occurred in 1981 or earlier. SITE CONDITIONS A plan of the site is shown in Figure 1. The site covers approximately 7 acres and is nonuniformly shaped, being bounded on the south and west by Slade - 4 - GeoEngineers Incorporated • Way and on the east by the Interstate Highway No. 5 right -of -way. A sanitary sewer runs along contour near the eastern boundary of the site. There are some indications that both surface and subsurface drainage facilities have been con- structed at the site. Cast iron horizontal drains were observed scattered across the site. The site slopes moderately to the east and northeast with isolated areas becoming moderately steep. A large drainage swale transects the southern portion of the site, resulting in the sewer alignment being displaced to the west. There are three benches on the site that appear to be manmade. The presence of the benches is significant in that they may signify previous slide activity. The first bench was constructed during the installation of the sanitary sewer line and essentially follows the sewer alignment to a point where the sewer line crosses the property line at the center of the eastern property line. Slopes downslope from the sewer bench in the southeast corner of the site are moderately steep. A second bench starts at the southern property line slightly upslope from the sewer bench and is oriented approximately parallel to the sewer bench for approximately one -third the length of the site at which point it disappears. The third bench is located in the center of the site and may have been constructed during installation of an old surface drain in this area. Vegetation consists of areas of very dense berry vines, some exceeding 10 feet in height, fairly dense alder groves, scattered evergreen trees, particu- larly on the western portion of the site, and occasional horsetails, which are indicative of wet ground. Most of the alder trees located on the middle to eastern portion of the site appear to be fairly young, indicating that they have grown since the slide in 1960 -61.. Wet'surface conditions were observed over much of the site at the time of our investigation. There appear to be several seeps or springs, some of which may be originating from old horizontal drains. The other seeps may be natural or may also be originating from covered up horizontal drains. Several erosion gullies are evident. A stormwater drain is located near the intersection of Slade Way and Southeast 53rd Street and appears to parallel Slade Way to the south, before proceeding downslope. The drain was leaking several gallons per minute at the time of our explorations. - 5 - GeoEngineers Incorporated SUBSURFACE CONDITIONS Subsurface conditions were explored at the site by drilling 8 borings using a truck - mounted, hollow -stem auger drill rig. The borings were drilled during October 13 to October 21, 1983. Because of wet conditions at the site and rela- tively steep slopes, a dozer was required to assist the drill rig in moving around the site. An engineer from our staff located the borings, maintained logs of the explorations, and obtained relatively undisturbed samples for ob- servation and laboratory testing. The boring locations are shown on Figure 1. Details of the field explorations, along with the boring logs edited to reflect laboratory examination and testing, are presented in Appendix A. Piezometers were installed in all borings except Boring F where an inclinometer casing which will permit future monitoring of slope movements was installed. The piezometer in Boring J has tips placed at two elevations. Details of the piezo- meter and inclinometer instrumentation are presented in Appendix B. Subsurface conditions at the site are defined from borings in the 1960 and 1961 investigations and from the current drilling program. Three major units were identified at the site as follows: UNIT A: Fill and /or slope debris, probably native to the site and consist- ing of loose to medium dense silty fine to medium sands. Thickness varies between 5 and 10 feet. UNIT B: Gray silt interbedded with fine to medium sand. The gray silt varies in consistency between medium stiff to very stiff, generally becoming stiffer with depth. The silt has some zones which contain a trace to some clay. Slickensides are present throughout the unit 'as well as randomly oriented contacts between different gradations of materials. The sand layers appear to vary from 1/8 of an inch to a couple of feet in thickness and are generally saturated. UNIT C: Gray sandy silty gravel and gray gravelly sand with some silt. Consistency varies from dense to very dense and unit is generally saturated. Unit B generally grades into Unit C and is separated by a layer of gray fine to medium silty sand in some of the borings The three units vary significantly both in depth and elevation across the site. As shown in the cross section in Figure 3, the units tend to follow the existing topography and slope down to the east. The thickness of the gray silt (Unit B) is less toward the south (25 feet in Boring C) and increases to the north (89 feet in Boring K). The dip of the surface of Unit C is to the northeast and may represent an erosional feature in Unit B. - 6 - GeoEngineers Incorporated ' GEOHYDROLOGICAL AND SURFACE WATER CONDITIONS The effect of surface runoff during periods of precipitation and spring activity is evident from several erosional gullies at the site. In general, the surface was wet and muddy during our explorations and the vegetation indicates that there is near - surface moisture year- round. The piezometers are installed in Unit C with the exception of the second piezometer tip in Boring J which was installed in Unit B at a depth of 20 feet. The piezometer levels, measured on November 18, 1983, are presented in Appendix B. In general, the water levels in Unit C are significantly deeper on the western side than on the eastern side of the site, as shown in Figure 3. At Borings C and H, the piezometric level is approximately 40 feet below ground surface while at Borings D and G the piezometric level varies between 6 and 11 feet. The two piezometers in Boring J indicate water level depths of 11 and 27 feet for the shallow and deep piezometer tips, respectively. Ground water conditions in Unit C were observed to change significantly after installation of the vertical well and horizontal drain system during con- struction of 1 -5. As noted in the 1960 and 1961 reports, artesian conditions (ground water levels above the ground surface) were reported in most of the borings at the site. While it is difficult to quantify how much effect the drain system has had on ground water levels, it is evident that water levels have decreased by a minimum of 6 feet at the time of our readings. A more important question, in our opinion, is whether the performance of. the drains is deteriorating due to siltation or other causes. This issue is discussed subse- quently. CONCLUSIONS AND RECOMMENDATIONS GENERAL We conclude that development of the property as planned is feasible pro - viding that adequate maintenance of the existing deep drainage facilities is accomplished and that the installation of shallow drains on the upper portion of the site is accomplished. There are two principal mechanisms of slope insta- bility which could damage the property. These include deep- seated sliding in a zone of soil from 30 to 50 feet below the surface and surficial sliding in the upper unit of soil, generally extending to a depth of about 10 feet below the present ground surface. The potential for movement of the hillside in the deeper zone of soils is largely controlled by the continued satisfactory performance of the vertical - 7 - GeoEngineers Incorporated well /horizontal drain system which was installed during construction of Inter- state Highway S. From our review of available information, iti6ppear) that the overall site stability in the approximately 20 years since these drains have been constructed has been good and that, the drainage system continues to be generally effective in preventing deep- seated movements. It is of prime importance, however, that the system remain fully operational. If the drainage system should deteriorate so that artesian pressures can again increase beneath the hillside, the risk of deep - seated and extensive earth movements can be expected to significantly increase. The second mechanism of shallow- seated movements is largely affected by surface runoff and near - surface infiltration of rainfall and runoff from higher ground. Based on the approximately 200 - foot -long scarp that was observed in 1982 and considered to be indicative of recent movement, it is evident that surficial movements are still relatively active in the southern portion of the property. We recommend that surface and near - surface drainage on the site be improved by constructing an interceptor ditch along the westerly limits of the property adjacent to Slade Way, together with installation of various drainage facilities in connection with site grading and building construction which are discussed subsequently. The piezometers and slope indicator which have been installed as a part of this investigation form the basic components of an instrumentation program to monitor long -term behavior of the property. We recommend that this instrumenta- tion program be extended once construction is begun. Immediately after site grading, we recommend that a series of settlement and alignment hubs be installed in areas where they will be relatively safe from subsequent construction activ- ities and destruction. The hubs should be initialized (surveyed in) immediately and monitored on a regular basis thereafter. The system of piezometers con- currently in place should also be maintained and monitored on a regular basis. In particular, the piezometers will need to be maintained during the construc- tion period. Losses should be anticipated due to equipment traffic. A long- term monitoring program should be initiated and we recommend that you assign specific individuals /companies to provide these services. Further details are included in this report. Earthwork on this property will be very difficult. We recommend that site grading be undertaken during the late summer -early fall months when the least amounts of rainfall can be expected and surface runoff and seepage • GeoEngineers Incorporated from springs should be somewhat diminished. Depending upon the overall con- struction schedule for the project, it may not be possible to accomplish all earthwork and drainage - related activities as well as foundation construction in a single dry season. Therefore, we suggest that construction activities be scheduled so that site grading, drainage installation and surface stabilization, if not final paving, is completed in any given area within a single construc- tion season. No area should be left partially graded or without sufficient drainage capability as this could endanger the near - surface stability of that portion of the site if left through a winter and spring season. Several of the planned condominiums will be located above the existing sewer, as shown on the Site Plan, Figure 1. This is significant from two aspects; first, access for repair work will be difficult, and second, we understand that the pipe backfill was not compacted, which will result in some additional over - excavation and replacement of fill beneath the buildings. We understand that the depth of the sewer averages 10 feet and ranges from 6 to 14 feet across the site. At these depths, the 12 -inch ductile pipe is considered to be structurally adequate to withstand foundation loads which are imposed near or at grade. However, the risk of creep displacements and partings at the joints is still present. Placing the pipe in a sleeve will reduce the effects of any soil creep. Also, it will make access to the line easier should repairs be needed. The pipe can be sleeved as a part of the remedial work on the existing backfill. EVALUATION OF I -5 DRAIN SYSTEM The operational life of horizontal drains is not well known. Depending on the soil type into which the drain is installed, the installation method and other factors, drains may operate satisfactorily for many years; however, drains are also known to silt up or clog due to corrosion or growths within the slotted sections of pipe and stop or lose considerable operating effectiveness after a few years. There appear to be no data available to assess the relative perform- ance of the drains at this site over the last few years. However, there are records of the water levels during the period December 1966 to June 1968 for several piezometers located immediately east of the site. The location of these piezometers and the layout of the horizontal drains is shown in Figure 2. The piezometric elevation before and after drain installation during this period are tabulated below: GeoEngineers Incorporated Piezometric Elevations (Feet) Pre and Post I -5 Drain System Installation Pre Drain Post Drain Net Piezo- Tip Water Water Elevation Drawdown meter Elevation Elevation Dec. 66 Oct. 67 June 68 (Feet) Lk 85 155 101 92 90 65 18 103 115 109 97 100 15 • 19 52 149 111 111 122 .27 232 49 72 65 60 77 -5 1 80 162 103 102 110 52 2 86 153 130 122 123 30 3A 90 137 105 99 120 17 The tabulated data indicate that, with the exception of Piezometer 232, the piezometric surface was still lowered between 15 and 65 feet approximately 3 years after installation. More importantly, there appears to be no general degradation of the efficiency of the drains during this period. Based on these data and our experience, we believe that the drains will operate for many more years. However, we also believe that the effectiveness of the drains will deteriorate slowly over a period of years. Should this occur, additional drains should be installed as necessary to control the rise of the water level in Unit C. We consider it important to begin a monitoring program of the piezometric levels at this time so that a general trend in the piezome- tric levels can be established. STABILITY No new information became available during this investigation to supercede the existing evaluated mechanism for sliding at the site, that is, the presence of a silt with a trace to some clay in conjunction with artesian pressures. In general, not much clay was encountered in the subsoils during this investigation and the reason for the flat slopes along which some of the sliding has occurred remains partially unresolved. Typically, for the soils encountered at the site, slopes should be stable up to 40 percent (211 to 1) in dry conditions and 20 percent (5 to 1) in wet conditions. Slopes at the site are generally on the order of 20 percent, steepening in places to 35 percent. Minimizing infiltration and subsurface flow will significantly improve the stability of the slopes. - 10 - GeoEngineers ' Incorporated Under these marginal conditions, a uniform slope provides the most favorable circumstances to minimize slope movements. Thus, local oversteepening due to freestanding roadway cuts should be avoided and all cuts steeper than 3:1 (hori- zontal to vertical) (33 percent) should be supported. SITE GRADING, INTERCEPTOR TRENCH AND SURFACE DRAINAGE A key element of site grading will be the collection and control of surface runoff and near - surface seepage. We recommend that temporary drainage ditches be installed to collect these flows immediately following site clearing and grubbing. In addition, prior to site clearing, we recommend that an interceptor trench be installed at the toe of the roadway fill along the western boundary of the site. The location of the interceptor trench is shown on Figure 1. The trench should be approximately 2 feet wide and not less than 7 feet deep. It should preferably extend to the top of the gray silt which varied between 7 and 12 feet in the three closest borings. The trench should be lined with a mono - filament filter fabric such as Mirafi 700X, with not less than 2 feet of overlap of adjacent sections of fabrics. A 6 -inch smooth -wall perforated pipe should be fully bedded in a well - graded sand or in clean gravel at the bottom of the trench. The remaining trench backfill should be clean,free- draining sand and gravel. The filter fabric should cover the free- draining fill with a fabric overlap of 12 inches below the surface and be covered with the silty native soil. We recommend that permanent French drains be installed along the upslope sides of all parking areas. These drains should be at least 5 feet below fin- ished grades and should consist of perforated pipe fully bedded in a graded sand filter or in clean gravel which is, in turn, enclosed in a filter fabric envelope. The remaining trench backfill should consist of clean, free - draining sand and gravel. A similar drain should be installed in wet areas along the east side of the condominium units. Flow from these drains may be combined with flow from footing drains and downspouts for disposal in a storm drain system; however, the design of connecting pipes should be such to present backflow into sections of perforated pipe. Use of the on -site soils for fill may be limited. We anticipate that the soils in their natural state will be above optimum moisture for effective com- paction. In order to use these soils, drying will be necessary. Also, we rec- omment that only clean granular soils be used for fill behind retaining structures. GeoEngineers Incorporated While careful segregation of the natural soils during excavation may provide a source of suitable backfill, we anticipate that much of the backfill behind walls will have to be imported. We recommend that temporary cut slopes be made no steeper than approximately 11:1 (horizontal to vertical). The stability of these cut slopes will be rela- tively low. Our analyses indicate that the factor of safety under static condi- tions will be on the order of 1.2 to 1.3 (a factor of safety of less than 1.0 indicates an unstable condition). Some sloughing or localized sliding should be anticipated, particularly where zones of seepage are encountered. When the excavations are made for the various buildings, we recommend that the construc- tion be sequenced so that alternate building sites are excavated, retaining walls built and adequately braced, and backfill placed before beginning excava- tion for the intermediate buildings. Permanent cut or fill slopes should be established at no steeper than 3:1. Slopes should be seeded as soon as practical. Localized seeps which are not intercepted by the general drainage facilities may have to be drained and /or excavated and backfilled with gravel or crushed rock to resist damage to the slope face. STRUCTURAL FILLS AND PAVING All structural fill should be placed in relatively thin (8 to 10 inches) layers and uniformly compacted. Backfill against retaining walls, particularly those in the structures, should not be overcompacted. A compaction of 90 to 92 percent of the maximum dry density determined by ASTM D -1557 should be achieved. Fill beneath paved areas or forming slopes should be compacted to 95 percent of maximum density. We understand that access roadways and parking areas will be paved with asphaltic concrete. Prior to placing base course material, we recommend that the exposed subgrade be thoroughly proofrolled. Any soft, loose or wet areas should be excavated and replaced with clean granular fill if the natural soils cannot be satisfactorily recompacted. Based on the existing surficial wet con- ditions, it should be expected that overexcavation and replacement of on -site soils with imported granular fill will be necessary over much of the roadway, parking area and portions of the sewer line. Overexcavation of 12 to 18 inches may be necessary for roadways and parking areas to establish a stable subgrade. All fill placed below subgrade level should be compacted to at least 92 percent - 12 - Incorporated of maximum dry density (ASTM D- 1557). A pavement section of 41 inches of clean pit run subbase, 11 inches of crushed rock base and 2 inches of asphaltic con- crete should be used. The extent of overexcavation and replacement of backfill along the existing sewer in areas to be occupied by buildings should be verified by examination during construction. As a worst case condition, the following may be necessary. Fill used to replace material excavated from the sewer line trenches should consist of clean granular soil. The existing backfill should be excavated from beneath the full building area and beyond for a distance of 4 feet on both sides to a depth of at least 5 feet below the bottom of the footing or to the top of the pipe, whichever is more shallow. The first foot of backfill over the pipe should be compacted to about 92 percent of maximum dry density and the remainder to 95 percent. RETAINING STRUCTURES Retaining structures are expected to be required for all of the buildings because of the sloping hillside. The units will be stepped into the hillside so that each section of retaining wall will be no more than one story high. The setback between walls is expected to be 15 feet or more. In addition, retention of cut slopes and fill embankments will be required along portions of the parking areas and near Unit Nos. 1 and 2. We recommend that lateral pressures on the basement walls be determined using an equivalent fluid pressure (psf) of 35 times the height of the wall in feet. This value applies only if clean, lightly compacted granular backfill is used against the walls and that a perforated drain is installed along the base of the wall to prevent the buildup of hydrostatic pressure. This value also applies only where the ground surface behind the wall is level for a distance equal to the height of the wall. If a sloping ground surface exists closer to the wall, this value may have to be increased. Retaining structures along the parking area and elsewhere outside of the buildings could consist of gabion basket walls, reinforced earth structures, or conventional poured concrete walls. We recommend against the use of rockeries except possibly for protection of low (less than 5 feet) cuts into natural soils. Rockeries should not be used to retain fill embankments. Where backfill behind the walls is level, lateral pressures may be determined using an equivalent fluid pressure (psf) of 35 times the height of the wall in feet. Where the surface slopes - 13 - GeoEngineers Incorporated upward behind the wall, an increased lateral pressure must be used. If a back - slope of 3:1 exists, we recommend that the lateral pressures (psf) be determined using 60 times the height of the wall in feet. We should review design criteria for other backslope configurations. Drainage of the backfill as well as cut slopes behind these retaining struc- tures is critical to their stability. The lateral pressure design criteria given above is based on drained conditions. For solid structures, such as a poured wall, a zone of clean backfill and a perforated drain should be installed. If gabion basket walls are used, we recommend that filter fabric be placed beneath and behind the baskets to prevent the retained soils from washing into the rela- tively open work gabion rock. A perforated base drain located immediately be- hind the baskets is also recommended for gabion installations. Resistance to lateral loads on retaining structures may be developed by passive pressures and base friction. We recommend that passive pressures be determined using an equivalent fluid density of 200 pounds per cubic foot. Base frictional resistance can be determined using a factor of 0.3 times the vertical downward component of long -term loading. These values incorporate a factor of safety of about 1.3. FOUNDATION DESIGN We recommend that the lowest floor grade of each condominium structure be established at an elevation such that a shallow foundation system will bear directly on natural soils below the topsoil layer. We recommend specifically against supporting structures on a combination of cut and fill areas. It may be necessary to overexcavate and replace some of the native materials if soft, wet conditions are encountered during construction. This will probably occur all along the sewer line, as previously discussed. Overexcavation /replacement will be satisfactory providing that any fill which is placed does not extend above the original ground surface elevation. We suggest the use of a foundation system consisting of a thickened slab system that will provide more rigidity and resistance to slight differential moavements across a structure than that which would be provided by continuous wall footings and a slab -on -grade system. The foundation system should consist of thickened edges around the perimeter of the slab and thickened sections beneath bearing walls within the buildings. Continuous reinforcing between the thickened edges and across the slab consisting of reinforcing bar rather than steel mesh should be provided. - 14 - The thickened edge sections should extend at least 18 inches below lowest adjacent finished grade and should have a base width of at least 18 inches. The thickened edge portion of this foundation system may be proportioned using a bearing value of 2,000 pounds per square foot. This value applies to the total of all design loads including wind or seismic, but excluding the weight of the footing and any overlying backfill. Care must be taken in preparing the subgrade for the thickened slab founda- tion system to avoid disturbance to the bearing materials. Any seepage which is encountered should be collected and diverted from the building area. The prepared bearing surfaces should be examined by one of our staff to determine that suitable preparation has been accomplished. It may be necessary to move and replace soft, wet or otherwise disturbed soils and to install localized drainage facilities to handle any seepage within the building area proper. Any soft soil should be replaced with clean granular fill compacted to 95 percent of the maximum dry density. We recommend that the bearing surface be protected from disturbance during reinforcing steel placement and concrete pouring by placing a 4- inch -thick layer of clean sand or sand and gravel compacted to a moderately dense state. Overcompaction should be avoided to prevent pumping if the subgrade soils are wet. We recommend that foundation drains be installed along the outside of the thickened edge sections of the foundation system. These drains, together with the drains for the retaining wall sections of the buildings, should be connected to tight drain lines along the east property lines so that flow can be conducted off -site for disposal in a means which will not adversely affect the stability either of this site or the hillside to the east. Settlement of the foundation system designed and installed as recommended above is expected to be relatively small, probably on the order of 1/2 to 3/4 of an inch. Some differential settlement may occur across units because of the differences of relief of overburden pressure resulting from the varying depths of excavation to establish lowest floor grade levels. MONITORING The purpose of the instrumentation program and long -term monitoring at the site is to establish base line data for the performance of the horizontal drain system and hence to set up an early warning system if a reduction in the stability of the slope occurs. We recommend that the settlement hubs and piezometers be - 15 - GeoEngineers Incorporated initially monitored twice a year, in February and August. Any changes in hub locations or deviations from previous piezometric levels should be considered cause for review of stability conditions by our firm. Additional readings may be needed to monitor whether or not changes reflect seasonal variations or im- pending stability problems. The inclinometer casing should be read annually in conjunction with the February readings. Indications of serious movements could trigger the need for installation of additional drains or maintenance of the existing system. Therefore, it is important that this monitoring program be accomplished in a dependable manner. USE OF THIS REPORT This report has been prepared for use by Dr. H. M. Allenbach and other mem- bers of the design team. This report should be provided to prospective contrac- tors for bidding and estimating purposes. Our report, conclusions and interpre- tations should not be construed as a warranty of subsurface conditions. As noted previously, we have used data developed by others at widely spaced locations. If there are changes in the loads, grades, location, configuration or type of construction planned from that which we have been provided, the conclusions and recommendations presented may not be applicable. If design changes are made, we request that we be given the opportunity to review our conclusions and recom- mendations and to provide a written modification or verification. When the design has been completed, we recommend that the appropriate construction drawings and specifications be reviewed by our firm to see that our recommendations have been interpreted and implemented as intended. The scope of work does not include services related to construction safety precautions and our recommendations are not intended to direct the contractor's methods, techniques, sequences or procedures, except as specifically described in our report for consideration in design. There are possible variations in subsurface conditions between the explora- tions and also with time. A contingency for unanticipated conditions should be included in the budget and schedule. Sufficient monitoring, testing and consul- tation by our firm should be provided during construction to confirm that the conditions encountered are consistent with those indicated by the explorations, to provide recommendations for design changes should the conditions revealed during the work differ from those anticipated, and to evaluate whether or not earthwork and foundation installation activities are completed according to the intent of contract plans and specifications. Within the limitations of scope, schedule and budget for our work, we war- rant that our work has been done in accordance with generally accepted practices followed in this area at the time the report was prepared. No other warranty, express or implied, is made. The conclusions and recommendations in this report should be applied in their entirety. We are available to review the final design and specifications to see that our recommendations are properly interpreted. If there are any questions concerning this report or if we can provide additional services, please call. GMD:JKT:wd �1„a.' . : •rya. • S �•�. 1 • • • a • GO e rsp • Yours very truly, GeoEngineers, Inc. Ac2,% ordon M. Denby Senior Engineer Jack K. Tuttle President - 17 - k Wifie GeoEngineers Incorporated • 12" DIAMETER DUCTILE IRON SEWER LINE NOTE: PROPOSED INTERCEPTOR TRENCH TO BE LOCATED IN THE FIELD. TRENCH TO BE ALIGNED ALONG CONTOUR AND DRAIN FROM NORTH TO SOUTH. REFERENCE: DRAWING ENTITLED "VALLEY VIEW ESTATES" BY WILSEY C HAM INC, DATED 5/3/82 CleoEngineers Inc. D EXPLANATION: BORING LOCATION AND LETTER DESIGNATION 0M -1 9 DAMES 6 MOORE INVESTIGATION 1961 0 80 160 SCALE IN FEET FIGURE 1 SITE PLAN — — — — — — — — — — — — FIGURE 2 4;,un p : -C `1._:- 'o 17..404. _.. 40 60 Project Site Approximate Extent of Slide 4-20-61 0 100 200 300 Scale In Feet Legend: Horizontal Drains (existing) o Original Test Drains o-------Recommended Drain (Grade: 1 -3 %) Cylinder Pile Wall AAA,A,Existing or Proposed Right of Way Reference: Drawing entitled 4. Additional Vertical Drains (6 -9 in. dia.) "Plan of Completed Remedial Measures" by Shannon & Wilson • Large Diameter (5') Deep Well dated March 31, 1966. _L:1___1„. Final Excavated Slope (horizontal:vertical) • Piezometer Installed During 1966 Investigation • GeoEngineers Inc. i HORIZONTAL DRAIN AND WELL SYSTEM FIGURE 3 ELEVATION IN FEET A 240- 200^ 160- 120- PROPERTY LINE .o z ESTIMATED PERCHED WATER TABLE 0 0 WATER TABLE IN UNIT C J yawl IMP- Mil. 0 LL Z 0 z 0 C-4 0 m PROPERTY LINE • • UNIT C AI ^240 -200 - 160 - 120 80- -80 i UNIT A GRAY SILTY SAND AND SANDY SILT (COLLUVIUM AND SLOPE DEBRIS) 'J UNIT B GRAY SILT WITH INTERBEDDED WET SILTY SAND TO SAND LAYERS; SLICKENSIDES TOWARDS BASE OF UNIT. I• UNIT C GRAY SAND AND GRAVEL INTERBEDDED WITH SILT LAYERS; WET. ELEVATION IN FEET HORIZONTAL SCALE: 1" = 20' DATUM: CITY OF TUKWILA GeoEngineers Inc. CROSS SECTION A -A1 APPENDIX A FIELD EXPLORATIONS AND LABORATORY TESTING FIELD EXPLORATIONS Subsurface soil and ground water conditions at the site were explored by drilling 8 borings at the locations shown on the Site Plan, Figure 1. The borings were generally terminated in the waterbearing sand and gravel layer. Total lineal footage was 572 feet. The borings were drilled using a truck - mounted, 4 -inch inside diameter, hollow -stem auger drill rig. Observation wells consisting of 1/2 -inch PVC pipe with a slotted tip were installed in each boring, except Boring F, after drilling was completed. A double installation was used in Boring J where a well tip was installed at the bottom of the hole and at the contact with the silt at 20 feet depth. A slope inclinometer casing was installed in Boring F in order to permit measurement of any future movements in the slope. A geotechnical engineer from our staff was present during the explorations. Our representative assisted in locating the borings, obtained representative soil samples, examined and classified t'he soils encountered, observed ground water conditions and maintained a detailed log of each exploration. The soils were classified in accordance with the Unified Soil Classification System which is described on Plate A -1. The logs of the explorations are presented on Plates A -2 through A -17. Relatively undisturbed soil samples were obtained from the borings using a heavy -duty sampler with 21/2-inch brass liner rings. The sampler was driven using a 250 -pound hammer falling a distance of 30 inches. The driving resistance for one foot of penetration is noted on.the logs adjacent to the sample notations. All samples were sealed in containers to limit moisture loss, labeled and taken to our laboratory for further examination and testing. LABORATORY TESTING Selected samples were tested to determine the field moisture and density and strength characteristics. The moisture - density data are presented on the logs of the explorations next to the appropriate sample notations on Plates A -2 through A -18. A - 1 PLATE A- BORING LOG AND SAMPLE DATA KEY DRIVEN SAMPLES BLOWS REQUIRED TO DRIVE SAMPLER MOISTURE CONTENT 28 11.2% 111 II DRY DENSITY ® IN PCF ❑ ONE FOOT OR INDICATED PENETRATION USING POUND HAMMER FALLING INCHES "P" INDICATES SAMPLER PUSHED WITH WEIGHT OF HAMMER INDICATES LOCATION OF UNDISTURBED SAMPLE INDICATES LOCATION OF DISTURBED SAMPLE INDICATES LOCATION SAMPLING OF ATTEMPT WITH NO RECOVERY GRAPHIC LOG OTHER TYPES OF SAMPLES SM LETTER SYMBOL SOIL TYPE DISTINCT CONTACT BETWEEN SOIL STRATA GRADUAL CHANGE BETWEEN SOIL STRATA INDICATES LOCATION OF THIN WALL, PITCHER, OR OTHER TYPES OF SAMPLES (SEE TEXT) 7 BOTTOM OF BORING UNIFIED SOIL CLASSIFICATION SYSTEM MAJOR DIVISIONS LETTER SYMBOL DESCRIPTIONS COARSE GRAINED SOILS MORE TMwN 50% CF MATERIAL IS L & TW4 NO. zoo SIEVE SIZE GRAVEL AND GRAVELLY SOILS , sox IcRE CF COARSE FRAC- TIONgTAfD ON NO. A SIEVE CLEAN GRAVELS (LITTLE OR NO FINES) GW AEU- c ctuvEls. +AVEL -SAND MIXTURES, LITTLE DR NO FINES GP P tv- GRAOEO canvELS. aAVEL- SMO MIXTLaES. LITTLE DR IC FINES GRAVELS WITH FINES (APPRECIABLE NOWT CF FINES) GM SILTY GRAVELS. GRAVEL -SAO -SILT MIXTRES GC CLAYEY GRAVELS.. GRAVEL -SAND -SILT ■Ii'URES SAND AND SOILS KM T14V4 SOX OF COARSE FRAC- TIM Miklfi C. • SIEVE CLEAN SANDS (LITTLE aR NO FINES) SW WELL 'GRACED SAW ND S. GRAVELLY SAS. LITTLE DR NO FINES SP SP POORLY- GRADED SANDS. GRAVELLY SMQS, LITTLE OR Na FINES SANDS WITH FINES (APPRECIABLE AMOUNT CF FINES) SM SILTY SMOS. SAW -SILT MIXTLRES SC CLAYEY SA OS. SAND-CLAY WI XTIRES FINE GRAINED SOILS MC RE TwN Sox CF MATERIAL INO. SMALLER 1NAN 200 SIEVE SIZE SILTS AND CLAYS LIQUID LIMIT LESS THAN 50 ML INORGANIC SILTS. AND VERY FINE SANDS. ROCK FLOUR. SILTY OR CLAYEY FINE SANDS OR CLAYEY SILTS WTTN SLIGHT PLASTICITY CL INORGANIC CLAYS OF Law TO mEDIw PLASTICITY. GRAVELLY CLAYS. SMOY CLAYS. SILTY CLAYS. LEAN CLAYS OL ORGANIC SILTS Mc ORGANIC SILTY CLAYS OF LOW PLASTICITY SILTS AND CLAYS LIQUID LIMIT GREATER THAN 50 MH INORGANIC SILTS. MICACEOUS OR DIATO- NACEOUS FINE WO DR SILTY SOILS CH INORGANIC CLAYS OF NIGH PLASTICITY FAT (LAY'S OH ORGANIC CLAYS >i WEDIUw TD NIGH PLASTICITY. ORGANIC SILTS HIGHLY ORGANIC SOILS PT PEAT. •AAUS. SWAP SOILS WITH HIGH ORGANIC CU TENTS NOTE. DUAL SYMBOLS INDICATE BORDERLINE SOIL CLASSIFICATION GeoEngineers Inc. 9 UNIFIED SOIL CLASSIFICATION SYSTEM AND KEY TO SAMPLE DATA PLATE A -2 0 5 BOR I , JG C ELEVATION: 237.1 FEET GRAPHIC TEST DATA LOG DATUM: CITY OF TUKWILA DESCRIPTION H 4410 z a 15 20 - 25 30- 35- 40 - 5 23.8% 99.1 9 31.9% 91.5 U 29 31.2% 91.7 11 28.3% 94.2311 32 24.5% 100.9 53 24.6% 100.5 54 6.9% 98.311 53 9.6% 122.811 S M ML ML SP BROWN SILTY SAND WITH GRAVEL (STIFF, MOIST) GRAY SANDY SILT WITI -I RUST STAINS (STIFF, MOIST) GRAY SILT WITH WET FINE SANDY SILT INTERBEDDED (STIFF, MOIST) SLICKENSIDES SLICKENS IDES FINE SANDY SILT LENSES S L I CKENS 1 DES GRAY FINE TO MEDIUM SAND (MEDIUM DENSE TO TO DENSE, MOIST) r HIT GRAVEL AT 38 FEET FOR 2 FEET, THEN SANDY, THEN BACK INTO GRAVEL *SEE KEY FOR EXPLANATION OF SYMBOLS GeoEngineers Inc. LOG OF EXPLORATION PLATE A -3 40 BORING C (CONTINUED) GRAPHIC TEST DATA LOG DESCRIPTION 45- w50-- z 55" 6 0 -r 65 70 75 51 14.30 116.111 93 34.90 82.71 50 4" 26.0% 99.011 50 5" 26.6% 98.711 50 52 16.1% 119.211 89 6" 4.0 159.8 11 7.10 60 6" ML GRAY GRAVELLY SANDY SILT TO SILTY SAND WITH SM WET FINE TO MEDIUM SAND LENSES (STIFF TO DENSE, MOIST) SM GRAY FINE TO MEDIUM SAND WITH SOME SILT, ORGANIC FRAGMENTS AND MICA (DENSE, MOIST TO WET) SHOE CONTAINED WOOD ML GRAY FINE SANDY SILT (STIFF, MOIST TO WET) SM ML GRAY GRAVELLY SILT WITH FINE TO MEDIUM SAND GM LENSES AND OCCASIONAL ORGANIC FRAGMENTS (STIFF TO VERY -STIFF, MOIST) GRAVEL AT 64 FEET BORING COMPLETED AT 73i FEET ON 10/20/83 PIEZOMETER INSTALLED AT 732 FEET ON 10/20/83 GROUND WATER LEVEL AT 64 FEET DURING DRILLING *SEE KEY FOR EXPLANATION OF SYMBOLS BORING D ELEVATION: 178.8 FEET *GRAPHIC *TEST DATA LOG DESCRIPTION 9 26.6% 91.111 14 30.9% 88.811 w 10- z 36 29.6% 93.111 15- 19 23.5% 100.911 20- 32 18.8% 110.611 25- 32 19.7% 110.911 30- 50 5,, 9.6% 35- 50 2" 6.4% 142.4® 40- ML BROWN AND GRAY SILT WITH ORGANIC FRAGMENTS AND ROOTS (STIFF, MOIST TO WET) (FILL ?) ML GRAY SILT WITH SOME RUST STAINS (STIFF, MOIST) LAMINATIONS DIPPING AT 20 °, OCCASIONAL CALCIUM CARBONATE CONCRETION ML GRAY SILT WITH POCKETS OF GRAY FINE SAND SM (STIFF, MOIST) OCCASIONAL GRAVEL WITH FINE SANDY SILT LENSES SLICKENSIDES GP GRAY SANDY GRAVEL (DENSE, WET) *SEE KEY FOR EXPLANATION OF SYM OT.S GeoEngineers Inc. LOG OF EXPLORATION 1 40 BORING D (CONTINUED) *GRAPHIC *TEST DATA LOG DESCRIPTION 45 - E• w 50- z w a 55- 60— 78 6" 7.3% 139.2g 11.50 50 311 g 50 4" 10.6% 130.80 19.7° GP //'/ GRAY SANDY GRAVEL WITH SOME SILT (DENSE, WET) GM 100 GM T g GRAY SILTY SANDY GRAVEL (DENSE, WET) 7 FEET OF HEAVE AT 572 FEET BORING COMPLETED AT 582 FEET ON 10/19/83 PIEZOMETER INSTALLED AT 582 FEET ON 10/19/83 *SEE KEY FOR EXPLANATION OF SYNBOT.S GeoEngineers Inc. LOG OF EXPLORATION 0 5 BORING F ELEVATION: 237.0 FEET *GRAPHIC *TEST DATA LOG DESCRIPTION w 10- z a 15- 20- 25- 30- 35- 40- 5 43.5% 70.911 7 35.0% 86.211 6 27.4% 96.111 14 27.0% 97.911 12 30.3% 93.811 35 30.6% 92.211 51 30.1% 92.511 65 24.3% 101.911 SM SM ML ML ML ML BROWN- BLACK -GRAY SILTY SAND WITH ORGANICS (MEDIUM DENSE, MOIST TO WET) (FILL) GRAY SAND WITH MICA (MEDIUM DENSE, MOIST TO WET) GRAY FINE SANDY SILT (SOFT, WET) GRAY SILT WITH A TRACE OF CLAY WITH SLICKENSIDES AND SOME WET FINE SANDY SILT LAYERS (MEDIUM STIFF, MOIST) GRAY SILT AND FINE SANDY SILT LENSES AND SLICKENSIDES (STIFF, DAMP) SLICKENSIDES GRAY FINE SANDY SILT WITH SLICKENSIDES (STIFF, DAMP) *SEE KEY FOR EXPLANATION OF SYM9OLS GeoEngineers Inc. LOG OF EXPLORATION 40 BORING F (CONTINUED) *GRAPHIC *TEST DATA LOG DESCRIPTION 45 - F V. 50- z a 55- 60- 65 -b 76 26.5% 97.311 34 20.6% 109.511 50 13.5% 122.611 50 2" 9.1% 117.611 50 11" • ML ML SP GM ML GM SOME FINE SANDY SILT LENSES GRAY SILT INTERBEDDED WITH FINE TO MEDIUM SAND (STIFF TO DENSE, MOIST TO WET) INCREASING GRAVEL CONTENT WITH DEPTH GRAY SANDY SILTY GRAVEL TO SANDY GRAVELLY SILT (DENSE TO VERY DENSE, MOIST TO WET) GRAY SANDY SILTY GRAVEL (VERY DENSE, MOIST TO WET) BORING COMPLETED AT 63 FEET 1 INCH ON 10/21/83 GROUND WATER LEVELS MEASURED AT 10.5 AND 53 FEET DURING DRILLING INCLINOMETER CASING INSTALLED AT DEPTH OF 63 FEET 1 INCH ON 10/21/83 *SEE KEY FOR EXPLANATION OF SY*BOLS GeoEngineers Inc. i LOG OF EXPLORATION PLATE A -8 BORING G ELEVATION: 179.2 FEET *GRAPHIC *TEST DATA LOG DESCRIPTION a A 15" 20- 25 30- 35- 40- 20 11.2% 105.011 20 25.9% 98.711 15 32.0% 90.311 16 25.7% 99.811 8 35.0% 86.511 18 32.3% 90.811 31 28.7% 92.711 57 27.7% 95.911 SM SM BROWN GRAVELLY SILTY SAND WITH SOME COBBLES (MEDIUM DENSE TO DENSE, MOIST) BROWN AND GRAY RED - STAINED GRAVELLY SILTY SAND (MEDIUM DENSE, MOIST) ML GRAY SILT WITH FINE SANDY SILT LENSES (STIFF, MOIST) r FINE SANDY SILT LENSES (MOIST TO WET) SLICKENSIDES DIPPING' AT 45° FINE SAND LENSES GRADES TO VERY STIFF AND DAMP SLICKENSIDES SLICKENSIDES WITH FINE SANDY SILT LENSES *SEE KEY FOR EXPLANATION OF SYMBOLS GeoEngineers Inc. LOG OF EXPLORATION PLATE A -9 40 *GRAPHIC_ *TEST DATA LOG BORING G (CONTINUED) DESCRIPTION 45- w 50- z a 55- 60- 65 - 70 -� 75 - 80- 32 25.1% 99.811 42 25.2% 100.311 21 24.8% 101.111 63 6" 24.00 101.211 86 6" 12.40 125.3® 50 1" 13.70 121.9® 70 6" 26.3% 99.411 25.3% 96.5 50 1 ML HIT GRAVEL AT 45 FEET ML GRAY SILT WITH FINE SANDY SILT AND FINE TO MEDIUM SAND LENSES (STIFF, MOIST) SLICKENSIDE SP SM GRAY FINE TO MEDIUM SAND WITH GRAY SILT INTERBEDDED (MEDIUM DENSE, WET) INCREASING'GRAVEL CONTENT GM GRAY SILTY SANDY GRAVEL (DENSE, MOIST TO WET) 2 FEET HEAVE AT 67.5 FEET SP GRAY FINE TO MEDIUM SAND WITH SOME GRAVEL AND OCCASIONAL GRAY SILT LAYER (DENSE, WET) BORING COMPLETED AT 781 FEET ON 10/18/83 GROUND WATER LEVEL AT 492 FEET DURING DRILLING PIEZOMETER INSTALLED AT 78'- FEET *SEE KEY FOR EXPLANATION OF SYMBOLS GeoEngineers Inc. 1 LOG OF EXPLORATION DEPTH IN FEET 0 BORING L ELEVATION: 207.5 FEET *GRAPHIC *TEST DATA LOG DESCRIPTION 10- 15- 20- 25- 30- 35- 40- 18 9.8% 122.511 6 35.4% 84.911 6 33.4% 89.111 8 26.1% 98.011 22 30.7% 92.211 34 29.9% 93.411 51 27.4% 97.011 43 27.6% 96.411 SM ML BROWN GRAVELLY SILTY SAND (MEDIUM DENSE, MOIST) GRAY SILT WITH REDDISH BROWN STAINS AND FINE SAND INTERBEDDED (SOFT, MOIST) r GRADES TO MEDIUM STIFF FRACTURES GRADES TO STIFF 1/8 INCH SAND LENS AT 28Z FEET GRADES TO VERY STIFF, DAMP SLICKENSIDE AT 371 FEET *SEE KEY FOR EXPLANATION OF SYMBOLS GeoEngineers Inc. 1 LOG OF EXPLORATION 40 *GRAPHIC *TEST DATA LOG BORING L (CONTINUED) DESCRIPTION 45- H w'50- z a A 55- 60- 65— 73 22.3% 104.411 86 25.8% 98.411 32 23.5% 104.411 52 6" 13.5% 125.911 Mt. 0 SM GRAY INTERBEDDED SILT AND FINE SAND (VERY STIFF, ML MOIST) FRACTURES AND SLICKENS[DES SP GRAY FINE SAND (LOOSE TO MEDIUM DENSE, WET) GM GRAY SANDY GRAVEL WITH A TRACE TO SOME SILT HEAVE AT 611 FEET BORING COMPLETED AT 63 FEET ON 10/14/83 GROUND WATER LEVEL ESTIMATED AT 49 FEET DURING DRILLING PIEZOMETER INSTALLED AT A DEPTH OF 63 FEET ON 10/14/83 *SEE KEY FOR EXPLANATION OF SYINBOLS GeoEngineers Inc. LOG OF EXPLORATION DEPTH IN FEET BORING H ELEVATION: 229.5 FEET *GFAPHIC *TEST DATA LOG DESCRIPTION 10- 15- 20- 25- 30- 35- 40- 6 21 30.5% 90.811 24 30.2% 92.411 22 28.6% 95.211 30.9% 92.2Il 24 25.6% 100.411 29 26.2% 99.711 SP BROWN SILTY FINE SAND WITH GRAVEL (MEDIUM DENSE, MOIST) (FILL) SP TAN TO BROWN FINE SAND WITH RUST STAINS (LOOSE, MOIST) ML GRAY SILT WITH SAND LENSES (STIFF, MOIST) 21 28.8 95.41 WITH A TRACE OF CLAY *SEE KEY FOR EXPLANATION OF SY?4BOLS GeoEngineers Inc. LOG OF EXPLORATION DEPTII IN FEET 40 *GRAPHIC. *TEST DATA LOG BORING H (CONTINUED) DESCRIPTION 45- 50- 55- 6o- 65- 25 33.1% 90.1. 34 29.9% 93.511 46 28.0% 95.911 66 28.2% 96.111 93 22.6% 102.811 WITH SAND INTERBEDDED, SLICKENSIDES, AND VERTICAL SAND /SILT CONTACT IN SAMPLE GRAY SILT INTERBEDDED WITH SAND VERTICALLY GRAVEL OBSERVED BY DRILLER GRAY SILT INTERBEDDED WITH SAND LENSE AT 70 DEGREE DIP GRAVEL IN BARREL ABOVE SAMPLE BORING COMPLETED AT 621 FEET ON 10/13/82 GROUND WATER OBSERVED AT 55 FEET DURING DRILLING PIEZOMETER INSTALLED AT 622 FEET *SEE KEY FOR EXPLANATION OF SYMBOLS GeoEngineers Inc. LOG OF EXPLORATION 0 BORING J ELEVATION: 195.4 FEET *GRAPHIC *TEST DATA LOG DESCRIPTION SM 50 6' 23.5% 87.011 5 20.- 25 30- 35- 40" ML 7 30.2% 90.411 5 28.2% 95.811 32.2% 17 • 18 31.6% 91.011 18 31.8% 88.011 24 32.4% 90.011 22 32.3% 90.011 BROWN GRAVELLY SILTY SAND WITH WOOD FRAGMENTS (MEDIUM DENSE, MOIST) GRAY SILT INTERBEDDED WITH SAND LENSES (SOFT, MOIST) GRADES TO STIFF WITH SLICKENSIDES AND FRACTURING FRACTURES SLICKENSIDES OCCASIONAL BROWN STAINS SLICKENSIDES *SEE KEY FOR EXPLANATION OF SYM13OT.S GeoEngineers Inc. LOG OF EXPLORATION HLATE A -15 40 *GRAPHIC *TEST DATA LOG BORING J (CONTINUED) DESCRIPTION 45- w 50- z a a 55- 60- 65- 75 - 80 — 25 30.9% 92.611 23 32.0% 90.111 29 33.7% 89.011 2 28.7% 93.71 96 23.6% 100.911 47 25.9% 89.811 106 18.3% 106.111 59 6" 18.7% 110.211 ML ML GP WITH SLICKENSIDES AND BROWN STAINS LARGE SLICKENSIDE GRADES TO VERY STIFF FEW SLICKENSIDES WET SAND LENSES AND RUST STAINS GRAY SILT WITH SOME GRAVEL, .SLICKENSIDES, RUST STAINS, AND SAND LENSES (VERY STIFF, DAMP) / HIT GRAVEL BETWEEN 77 TO 80 FEET *SEE KEY FOR EXPLANATION OF SYMBOLS GeoEngineers Inc. LOG OF EXPLORATION 80 85 DEPTH IN FEET *GRAPHIC *TEST DATA LOG j1LGF SP BORING J (CONTINUED) DESCRIPTION GRAY FINE TO MEDIUM SAND (MEDIUM DENSE, WET) HEAVE AT 821 FEET BORING COMPLETED AT 84 FEET ON 10/15/83 GROUND WATER LEVEL ESTIMATED AT 492 DURING DRILLING PIEZOMETER INSTALLED AT A DEPTH OF 822 FEET AND 20 FEET *SEE KEY FOR EXPLANATION OF SYMBOLS GeoEngineers Inc. LOG OF EXPLORATION PLATE A -17 BORING K ELEVATION: 175.0 FEET *GRAPHIC *TEST DATA LOG DESCRIPTION 13 21.7% 99.611 9 26.3% 97.011 E. 8 w 34.1% 87.711 A 15- 10 28.3% 97.011 20" 5 35.5% 87.311 25 20 29.8% 92.411 30- 20 26.4% 93.50 35- 36 26.1% 98.211 40- SM BROWN GRAVELLY SILTY SAND WITH RED AND DARK BROWN STAINS (LOOSE TO MEDIUM DENSE, MOIST) ML GRAY SILT WITH SAND LENSES AND RUST STAINS (STIFF, MOIST) MOTTLED APPEARANCE GRADES TO SOFT AND WET SLICKENSIDES GRADES TO STIFF AND MOIST TO WET SLICKENSIDES AND BROWN STAINS SLICKENSIDES AND BLOCKY FRACTURES *SEE KEY FOR EXPLANATION OF SYMBOLS GeoEngineers Inc. 1 LOG OF EXPLORATION PLATE A -18 40 BORING K (CONTINUED) *GRAPHIC *TEST DATA LOG DESCRIPTION 32 27.7% 95.911 45- 54 27.9% 96.711 V. 50- z H 31 w 27.1% 96.411 55-1 58 30.1% 93.011 60- 82 25.3% 98.411 65 76 27.0% 98.011 70" 50 4" 24.5% 101.311 75- 65 20.2% 110.011 80- ML MANY SLICKENSIDES VERTICAL COLOR CONTACT IN SILT SLICKENSIDES DISTORTIONS IN SAND LENSE SLICKENSIDES GRADES TO VERY STIFF MANY SLICKENSIDES SLICKENSIDE TRACE OF SOME VERY FINE SANDY WET VERY FINE SANDY SILT LENSES ML GRAY FINE SANDY SILT (STIFF, WET) 'Z'P-JBROWN SILTY SANDY GRAVEL (DENSE, WET) *SEE KEY FOR EXPLANATION OF SYMBOLS GeoEngineers Inc. 1 LOG OF EXPLORATION PLATE A -19 80 BORING K (CONTINUED) *GRAPHIC *TEST DATA LOG DESCRIPTION 70 6" 23.0% 104.011 85- 50 4" 25.9% 98.811 w 90- z a GP ML GRAY FINE SANDY SILT (STIFF, WET) BORING COMPLETED AT 88 FEET 9 INCHES ON 10/17/83 GROUND WATER LEVELS MEASURED AT 14 FEET AND 79.5 FEET DURING DRILLING PIEZOMETER INSTALLED IN GRAVEL LAYER AT 88 FEET *SEE KEY FOR EXPLANATION OF SYMBOLS GeoEngineers Inc. 1 LOG OF EXPLORATION APP END I X B INSTRUMENTATION PIEZOMETRIC LEVELS The piezometric levels as measured on November 18, 1983 are presented in Table B -1. INCLINOMETER DATA The inclinometer was initialized on November 1, 1983. A second set of readings was taken on November 18, 1983. The readings show no discernible movements at this time. The data are available for review or copying from our files. Boring No. C D G H J Top J Bottom K L Ground Surface Elevation Feet 237.1, 178.8 179.2 229.5 195.4 195.4 175.0 207.5 TABLE B -1 PIEZOMETRIC LEVELS Stick Up Feet 0.0 0.80 1.90 2.20 0.0 1.00 0.0 0.50 November 18, 1983 Reading Feet 40.46 6.93 17.80 42.55 11.31 28.61 70.49 30.42 Depth to W.T. Feet 40.46 6.13 15.90 40.35 11.31 27.61 45.49 29.92 Elevation of W. T, Feet 196.6 172.7 163.3 189.1 184.1 167.8 129.5 177.6 Appendix D Letters from Fire and Police Department August 30, 1983 Fire Marshal Jim Hoel Tukwila Fire Department 444 Andover Park E. Tukwila, WA 98188 RE: Valley View Estates EIS Dear Fire Marshal Jim Hoel: We are in the process of preparing an Environmental Impact Statement for a proposed 108 unit condominium development on 5.3 acres located between Slade Way, 53rd Avenue S., and the I -5 R.O.W. (see attached Vicinity Map). Access would be via Slade Way and 53rd Avenue S. Based on the following information, your comments will help us facilitate to produce a Working Draft EIS for the City's preliminary review. The proposed development consists of 18 6- plexes with 36 2- bedroom units and 72 1- bedroom units. Approximately 212 people would reside in the development. Parking would accommodate approximately 162 cars. A traffic engineer has been obtained to determine the adequacy of on and off -site circulation to withstand the demands created by the development. The type of information which would be helpful in addressing adequacy of service and impacts generated by the development are as follows: 1. Number of fire responses in the City; 2. Number of emergency medical service responses; 3. Type of responses (i.e., house fire, emergency medical, etc.) 4. Adequacy of fire flow in the vicinity; 5. Number of staff and type of equipment in affected fire station; 6. Emergency response time; 7. What is Tukwila's fire rating? 8. Would this project create adverse impacts on the service level to the rest of the City (appreciably create adverse impacts)? Fire Marshal Jim Hoel August 30, 1983 Page Two 9. Based on the . information provided, what mitigating measures would you suggest for the project which would lessen the impacts it would have on fire service? 10. Any other information you feel is pertinent to this project. Thank you for your assistance in this matter. Sincerely, Jon Potter JDP:rmc enc City of Tukwila � ��v� K�U "�~v��� ~~. Gary VanDusen Mayor Fire Department Mr. Jon Potter R. W. Thorpe & Associates 815 Seattle Tower Third & University Seattle, WashinE4ton 98101 Dear Mr. Potter: September 15, 1983 In reply to your letter of August 30, 1983: 1^ Total number of responses by the Tukwila Fire Dept. during 1982 was 896 Medical Aid 694 Fire & Service 2. Adeouacy of fire-flow in the area is not known. A flow-test will need to be conducted, 3^ Tukwila Fire Dept. employs 24 firefighters and officers, 3 staff personnel and one secretary. 4. Emer!Jency response time to this area is estimated at 3 to 4 minutes, averae. 5^ Fire ratinst of the City is - Class 4 6^ Refer to the enclosed copy of the May 12, 1982 plans review sheet for further comments and concerns. Yours truly, The Tukwila Fire Prevention Bureau cc:TFD file City Attorney Planning Dept. Encl.: May 12 Plan Review City of Tukwila Fire Dopartment, 444 Andover Park East, Tukwila, Washington 98188 (206) 575-4404 CI`iY OF TUKWILA PERMIT NUMBER - CONTROL NUMBER ?� -'693 • CENTRAL PERMIT SYSTEM - PLAN CHECK ROUTING FORM TO: BLDG, PLNG, P.W. FIRE 1 POLICE �,j. P.& R. PROJECT Va,Jl& — 'ADDRESS S3 P--AV � . DATE TRANSMITTED f� . / / °� RESPO SE REQUESTED BY v6?-f)",(1, �C.P, S, STAFF COORDINA 1' I RESPONSE RECEIVED PLEASE REVIEW THE ATTACHED PROJECT PLANS AND RESPOND WITH APPROPRIATE COMMENTS IN THE SPACE BELOW, INDICATE CRUCIAL CONCERNS. BY CHECKING THE. BOX NEXT TO THE LINE(S) ON WHICH THAT CONCERN IS NOTED: 1)l Oh qp -or ae "fir eXTi�G�v15h 1,, eir [/Yli } .. 2) F 1 L Si,oA detec-44 "s P vg Sec. I Z1C. 3)JI ire. "r /o!,. r ?[i /ren c+h 4-o J - e( L � �ut /A'd /J7 igh • )cvlre4 v • 4 %) 1iv� 4 f7Qw (p /,,.C_ f jo .,) )-€51- I /7r,nr �o CAy5�r•vc_74/bn• 10) ❑z � 111 l i El 13) ❑ lv LIu> wjl) �` •r'- r,,-�- G� C cr. 4 -414 d r;✓ ;i F�A'-,%tiy a'- S 9 dc. cl.e<<a "F re L4,, — No �br/rl,�" Dr.J,'h 44 Ce # ///e. fit— 2 f9O74 ��d V nob. ili- 2 (i cYrivi"A 14,, `S 11i fh • foo4 +vrhitiy r qel/ 15 ref tir tel Ov9�iov7e• fr L I r"o &C oy v L •C �. ♦ h A r• '- Li' /7911- cl ' 9$ 713 , • . J / 5�^i�%��ai Iced It 9A5 5 '"iniil e . IcHI1/15 N iraln 9A S 1M 2�'t.� hi e,4-l�� L. .,(� !� ..�i1w S/ o /—hyR � �r9w .S %o�hlR � y D, R, C, REVIEW REQUESTED El PLAN CHECK DATE , S- /2 - cs ® COMMENTS PREPARED BY (2,.2,7/• PPLAN RE.,c UBMITTAL REQUESTE G� 5'flri� h C,P,S, FORM 2 August 30, 1983 Lieutenant Phelan Tukwila Police Department Tukwila City Hall Tukwila, WA 98188 RE: Valley View Estates EIS Dear Lieutenant Phelan: We are in the process of preparing an Environmental Impact Statement for a proposed 108 unit condominium development on 5.3 acres located between Slade Way, 53rd Avenue S., and the 1-5 R.O.W. (see attached Vicinity Map). Access would be via Slade Way and 53rd Avenue S. Based on the following information, your comments will help us facilitate to produce a Working Draft EIS for the City's preliminary review. The proposed development consists of 18 6- plexes with 36 2- bedroom units and 72 1- bedroom units. Approximately 212 people would'reside in the development. Parking would accommodate approximately 162 cars. A traffic engineer has been obtained to determine the adequacy of on and off -site circulation to withstand the demands created by the development. The type of information which would be helpful in addressing adequacy of service and impacts generated by the development are as follows: 1. How many police officers are on staff; 2. Number of traffic accidents in the general vicinity; 3. Number of pedestrian accidents in the general vicinity; 4. Emergency response time; 5. Is the present service level adequate in the City? 6. Would the project create adverse impacts on the service level to the rest of the City (appreciably create adverse impacts)? 7. Based on information provided, what mitigating measures would you suggest for this project which would lessen the impacts it would have on the Police Service? Lieutenant Phelan August 30, 1983 Page Two 8. Any other information you feel is pertinent to this project. Thank you for your assistance in this matter. Sincerely, Jon Potter JDP:rmc enc , 0�c W� A 4s City of Tukwila ;1908 6200 Southcenter Boulevard Tukwila, Washington 98188 Police Department 433 -1808 Mr. Jon Potter R.W. Thorpe & Associates 815 Seattle Tower Third & University Seattle, Washington 98101 September 9, 1983 Dear Mr. Potter, jc\FETNIZ SEP 1 ? to R.W. THORPE & HS:;:CV„ E3 RT jp q t3 OK R5 Kf ATTN: Jon Potter This letter is in response to your Valley View Enviornmental Impact Statement questionaire dated August 30, 1983. 1. How many Police Officer on Staff? 25 Officers 2. Number of traffic accidents in general vicinity? Four in the last six months 3. Number of Pedestrian accidents in the general vicinity? Zero in the last 6 months 4. Emergency response time? Average 3 -5 minutes 5. Is the present service level adequate in the city? Yes 6. Would the project create adverse impacts on the service level to the rest of the city (appreciably create adverse impacts ?) Owner occupied condominiums have presented little in the way of problems for the Police Page 2 Appendix E Traffic Study VALLEY VIEW ESTATES Traffic Impact Analysis Prepared for Dr. Herman Allenbach Prepared by The TRANSPO Group, Inc. July 1984 TABLE OF CONTENTS Page INTRODUCTION 1 Project Location 1 Project Description 1 EXISTING CONDITIONS 3 Vicinity Street System 3 Traffic Volumes 5 Accidents 8 Parking 11 Transit Service 11 Pedestrian and Bicycle Travel 11 Planned and Programmed Traffic Improvements 13 FORECASTED TRAVEL DEMAND AND TRAFFIC ANALYSIS 14 INTRODUCTION A multi- family housing development is being proposed for the southwest quadrant of the Interstate 5 /SR 518 interchange area of Tukwila in south King County. In accordance with the directives of the City of Tukwila, The TRANSPO Group, Inc., a professional traffic engineering and transportation planning firm located in Bellevue, has prepared a traffic impact analysis of the pro- posed development. This report summarizes the results of that analysis. The purposes of the analysis are to identify any potential traffic related impacts generated by construction of the proposed multi - family development and, where appropriate, to outline policies, programs and /or physical improvements to minimize or eliminate the effects of these potential adverse impacts. Project Location Figure 1, Vicinity Map, depicts the general location of the proposed Valley View Estates multi - family housing development in the south Seattle/ Tukwila area. The project site is generally located in the southwest quadrant of the interchange of I -5 and SR 518. Specifically, the site is situated between Klickitat Drive on the east and north, 53rd Avenue S. on the west, and Slade Way to the south. Klickitat Drive and 53rd Avenue S. provide one of the primary access routes from the Southcenter /Tukwila area to the residentially oriented areas to the west and south. Project Description The proposed Valley View Estates residential development would have 108 units, equally divided among 1084 square feet (SF) 2- bedroom townhouses, 732 SF 1- bedroom flats, and 808 SF 1- bedroom townhouses. Current plans call for 18 individual buildings containing two each of the above described unit types. Project access is to be provided at the west side of the project off 53rd Avenue S. between Klickitat Drive and S. 158th Street, and at the south end of the project onto Slade Way. A total of 162 parking spaces is proposed, 30 percent of which would be striped for compact cars. —2— EXISTING CONDITIONS This section of the report describes the existing transportation condtions in the vicinity of the proposed Valley View Estates residential development, including the vicinity street system, traffic volumes, accidents, parking, transit service and pedestrian and bicycle activity. This discussion is intended to serve as a basis for the subsequent- analysis of the project - generated traffic. Vicinity Street System Figure 2 depicts the street system in the site vicinity which provides access from the Puget Sound /Seattle area region as well as the local neighborhood. Interstate 5 (I -5) provides the major north -south traffic corridor for regional travel in the site vicinity while Pacific Highway S., about one mile west of the site, provides some regional and more local thru travel in the area. To the north of the site, SR 518/I -405 provides an east -west traffic link between Burien and Renton as well as direct access into Sea -Tac International Airport. The City of Bellevue and other points on the east side are reached via I -405. More immediate to the site, Klickitat Drive provides a collector arterial function between and including 51st Avenue S. north of SR 518 and Southcenter Parkway. It is a two -lane street with 4 -6' paved and gravel shoulders in the vicinity of 53rd Avenue S. and the project site. Its roadway surface is in good condition. Except for the SR 518 eastbound off -ramp, 53rd Avenue S. and the I -5 southbound on -ramp, there are no other direct access locations onto Klickitat Drive. Adjacent land use to the north and east of Klickitat is primarily state highway right of way, while that to the south and west is nondirect access residential land use. 53rd Avenue S., south of Klickitat, rises southbound at approximately 4 -6 percent to S. 158th Street. It is in fair to good condition with adequate gravel shoulders. Its intersection with S. 158th Street is a "T" intersection with the south and west legs controlled by STOP signs. South of 158th Street, the roadway curves to the east, becoming Slade Way which continues on a down- grade to the east and narrows as it turns sharply to the south near I -5. -3- f` 1; ara v. 154TH ST 160TH ST Inf 4 —WAY STOP W /BEACON KL lac/ 5� PROJECT SITE S I\' �tirM SC ��rFR y` In4 164TH ST NF 166TH ST 40 inV SHARP CORNER/ NARROW STREET S 1- ce n 170TH ST to VI LL 176TH ST LEGEND: CA- SIGNAL S -STOP SIGN -MULTI —LANE (M OF LANES) 178TH ST ti gab as NO0TH STRMOER BL YO 180TH ST as as 0 C S VALLEY VIEW ESTATES Figure 2 VICINITY STREET SYSTEM The TTtANSPO The section of Slade Way on the 54th Avenue S. alignment is a very narrow section, little more than one lane in width. Additionally, shoulders are narrow to nonexistent with a tree growing near the edge of the pavement along the east side of the road. Farther south, Slade Way /54th Avenue S. swings west again and becomes 53rd Avenue S. which provides local access to an estab- lished residential area. The section of roadway near 166th Street has re- cently been widened by the City of Tukwila to a standard 26 -foot wide section. S. 160th Street, S. 164th Street and S. 170th Street provide the primary east -west local access roads in the area to the west between the project site, Military Road and pacific Highway S. These streets are generally two -lane residential roadways in fair to good condition with some local exceptions such as potholes and /or poor pavement. Shoulder width, although not narrow, is often used for residential vehicular parking. In general, residences in the vicinity front relatively close to the roadway edge, typical of numerous established medium density residential neighborhoods throughout the Puget Sound area. Military Road is generally a 2 -lane roadway, running northwest to south- east, with left -turn channelization provided at selected intersections. Traffic signals control intersections with S. 164th Street /42nd Avenue S. as well as at S. 176th Street. It is currently in good condtion within the project study area. Traffic Volumes Current traffic count information was collected from the City of Tukwila and King County. The traffic volumes represent counts taken in 1981, 1982 and 1983. Where available information was incomplete, The TRANSPO Group estimated the current traffic volume based on neighboring volumes and field observa- tions. Figure 3 illustrates these existing daily traffic volumes. As shown on Figure 3, the vicinity streets carrying the highest traffic volumes are in the Southcenter Parkway /Southcenter Boulevard area where vol- umes are typically in excess of 20,000 vehicles per day (vpd). West of the project site, traffic volumes on most local streets range from 200 vpd to about 4000 vpd. Most fall within the 500 to 2100 vpd range. This is typical of established residential neighborhood traffic patterns where some streets 29100 24200 25000 13800 154TH ST 14100 4800 1800 12300 112000• /A\ NOR T H 28000 sOur 182000' 67400 13300• 1800• 2200' 2100* 160TH ST 14500• 111000) 24000 17800 \164TH ST 1400• I` i STRA!CER el VD 166TH ST 242001 18200 170TH ST 5400 1900 28400 N 16100 1200) 11900 8500 7900 116000 20400.1 a cc 300001 *DENOTES ESTIMATE 176TH ST 110000' 17800 178TH ST 160TH ST VALLEY VIEW ESTATES Figure 3 EXISTING TRAFFIC VOLUMES The rRANSPO Grove function as neighborhood collectors, such as S. 160th Street, S. 170th Street and 53rd Avenue S. adjacent to the project site. Other streets such as S. 164th and S. 166th Streets function in a more locally- oriented manner, primarily serving the transportation needs of residents on that street. 53rd Avenue S. adjacent to the project site carries about 2200 vpd; however, south of S. 158th Street, where 53rd Avenue transitions into Slade Way, the volume drops sharply to about 200 vpd. This indicates that the primary travel pattern is to the west from 53rd Avenue to S. 158th /160th Street. 158th /160th Street carries about 2100 vpd near 53rd Avenue S. Klickitat Drive near 53rd Avenue S. and the project site carries between 13,000- 15,000 vpd, growing to over 20,000 vpd south of the I -5 southbound on- ramp. These volumes are consistent with those observed on many other col - lector arterials. While the daily traffic volumes provide a general impression of travel patterns, it is appropriate to examine evening peak hour traffic conditions since this is generally the time when traffic congestion becomes most notice- able. The TRANSPO Group made evening peak period traffic counts at the inter- sections of 53rd Avenue S. with S. 158th Street and Klickitat Drive as well as Klickitat Drive with the southbound I -5 on- ramp adjacent to the project. The peak hour was observed to occur between 4:00 and 5:00 PM at the Klickitat Drive /53rd Avenue intersection, and about 4:00 to 5:00 PM at 160th Street /53rd Avenue. These volumes were generally about 9 to 10 Percent of the daily traffic volume estimates shown on Figure 3. Techniques have been developed to assess the levels of congestion that result with different street and traffic volume conditions. These techniques are described in the Highway Capacity Manual and the Traffic Engineering Handbook and are referred to as levels of service (LOS) which range from LOS A which is very good, to LOS F which reflects a traffic flow that has deter- iorated to a start - and -stop condition. In urban areas most traffic engineers design improvements to operate at LOS C, but consider LOS D acceptable during peak periods as long as these conditions do not extend longer than one hour within the peak period. LOS E indicates that the roadway is operating at capacity. Currently, it is estimated that the intersections counted by The TRANSPO Group operate at acceptable levels of service during the PM peak hour. The busiest of these intersections was the intersection of 53rd Avenue S. with Klickitat Drive. Using TRB Circular 212 Techniques for Unsignalized T- intersections, the resulting level of service calculation indicated that right and left turns from northbound 53rd Avenue S. are currently operating at LOS C. This indicates that delays experienced by drivers attempting to make these movements are within an average range, and not uncommon to numerous other locations throughout the area. Left turns from Klickitat onto south- bound 53rd Avenue were calculated to operate at LOS A, indicating little or no delay. While these calculations indicate average conditions within the peak hour, observations by The TRANSPO Group indicated that sporadic backups behind left- turning traffic from Klickitat to 53rd Avenue extended to as many as 8 or 9 vehicles at times; however, these backups generally lasted less than a minute, typically clearing within a few seconds after the lead left -turn vehicle completed its movement. In addition, the wide lane and shoulder for westbound traffic on Klickitat allowed some vehicles. to pass the left - turning vehicle on the right. While existing striping does not encourage this move- ment, it would appear that adequate space is available to restripe the east leg of Klickitat with little if any widening to allow for left -turn channeli- zation, thereby eliminating delays to thru traffic as a result of left- turning traffic ahead. All other intersections in the immediate site vicinity operate well within the accepted range of delays for LOS A conditions. Accidents Traffic accident data over the period from 1980 through September 1983 was examined based on information supplied by the King County Traffic Engineer and the City of Tukwila. The average annual accident occurrence is depicted on Figure 4 for intersections in the project vicinity. Near the site, the inter- section of 53rd Avenue S. with S. 158th Street did not experience a reported accident in the study period. An average experience of 2.7 accidents annually occurred at 53rd Avenue S. and Klickitat Drive, while 0.3 accidents per year occurred at the intersection of Klickitat Drive with the I -5 southbound ramp and the intersection of Klickitat Drive with Southcenter Parkway. In the entire study area depicted on Figure 4, approximately 4 percent of the acci- dents occurring during the study period involved pedestrians. Of these, nearly half of the pedestrian accidents occurred on 170th Street at Military Road and 51st Avenue S. 0.7 1.8 LL a IS4TH 5T 4.4 160TH ST OD 2.2 2.9 1.1 2.9 1.1 10.4 1.8 2.21 0.4 0.4 0.7 0.41. 4.71 PROJECT SITE 10.4j 0.7 164TH ST 4.41 166TH ST 1.8 0.4 170TH ST 176TH ST 1.8 3 3 2.21 6.5 178TH ST TF /& NORTH -4 0: STRMDER BLVD 180TH ST VALLEY VIEW ESTATES Figure 4 AVERAGE ANNUAL ACCIDENTS (Jan 1981 to Sep 1983) The TRANSPO Group While average annual accident occurrence provides us with a good general indicator of high accident locations, to establish whether these locations are hazardous relative to other locations, it is necessary to examine the accident experience in terms of the total exposure at the particular locations. When examined in this light, the comparative tool used is termed accident rate. At intersections, accident rate is measured in terms of Accidents per Million Entering Vehicles (Acc /MEV). On street segments, accident rate is measured in terms of accidents per million vehicle miles (Acc /MVM). Since intersections typically provide the most opportunity for vehicle conflict, particularly in developed areas with a gridded street system, analyses of potential high accident locations are generally limited to critical intersection locations. Typical urban area accident rates for both signalized and unsignalized inter- sections range from 0.5 to 2.0 Acc /MEV. Based on this, the accident rates at a number of key intersections in the study area which experienced at least one accident per year on the average were examined: • 53rd Avenue S. and Klickitat Drive: • 51st Avenue S. and S. 160th Street: • 51st Avenue S. and S. 170th Street: • Military,Road and S. 160th Street: • Military Road and S. 170th Street: • Military Road and S. 176th Street: 0.5 Acc /MEV 1.4 Acc /MEV 1.1 Acc /MEV 0.6 Acc /MEV 1.1 Acc /MEV 1.2 Acc /MEV. The above accident rate data reveal no significant safety hazard at any of the above intersections based on accident experience. It is acknowledged, however, that all accidents are not necessarily reported at every location. Additionally, even those accidents reported typically require a minimum prop- erty damage estimate of $300 prior to being added to the accident record files for most jurisdictions. Some concern has been raised by City of Tukwila staff regarding rear -end accidents associated with the westbound -to- southbound left -turn movement from Klickitat Drive to 53rd Avenue S. Reportedly, thru vehicles westbound on Klickitat have rear -ended vehicles waiting in the queue caused by delays to left turning traffic. Examination of the available accident data indicated a repeating pattern of these rear -end accidents. However, the above accident rates indicate that the intersection as a whole is less hazardous than many other intersections in the immediate area. Installation of a left -turn lane for westbound approaching traffic at the intersection would eliminate much of -10- the potential for these types of accidents. Existing laneage and geometry indicate that this would be a relatively low -cost counter - measure for reducing these types of accidents. Parking Since the project site is currently undeveloped, there is no parking use of the site. Very sparse on- street parking was observed in the immediate site vicinity as residential development is sparse as well. To the west on top of the hill, between the project site and Military Road, as well as between Military Road and Pacific Highway S., on- street parking was generally sparse and associated with close fronting residences along the various streets. There was little evidence of any parking which encroached into the travel lanes for the vicinity streets. There was no parking observed along Klickitat Drive near the project site as there is currently no frontage of any traffic generating activity. Transit Service The project vicinity is currently well served by existing Metro Transit routes. Two transit routes pass directly adjacent to the site on Klickitat, routes 240 and 241. Route 240 utilizes 53rd Avenue S., 51st Avenue S. and S. 170th Street to Pacific Highway S. through the residential neighborhood west and south of the site. Route 240 serves Bellevue and Burien, running on one - hour off -peak headways and ? -hour peak headways. Route 241 bypasses the residential neighborhood bordering the project and continues west on Klickitat via SR 518 to Pacific Highway S. These and other transit routes in the gen- eral project vicinity are shown on Figure 5. Pedestrian and Bicycle Travel Field observations made during peak hours and at various times of the day including weekends showed that there were no significant numbers of pedes- trians or bicyclists in the immediate site vicinity. In areas where tradi- tional activity generation exist, such as community shopping centers, more activity was observed; however, it was still generally observed to be 1 - light. A few pedestrians were observed in the residential neighborhood to the southwest; however, the activity would be again described as very light. The 1979 Transportation Improvement Plan indicated that there are no bikeways along the arterial system within the City and no current plans to add them along major streets in the project vicinity. Physical factors, such as steep terrain, limit bicycle use as a practical commute mode for most poten- tial users. Planned and Programmed Traffic Improvements In order to accurately evaluate traffic impacts at the time the project is constructed, an attempt was made to determine the street system which would likely be in place for the project target year even if the project were not constructed. A review of the current 1984 through 1989 Six Year Transporta- tion Improvement Program (TIP) for the City of Tukwila was made. The follow- ing projects in the immediate site vicinity were identified which could impact or be impacted by the proposed Valley View Estates development. The work tasks for all projects involved grading, drainage, light bituminous surface treatment, A.C. or P.C.C. pavement, sealcoat, curb, gutter, sidewalks, light- ing and signing. The project limits are shown below: • 160th Street, 51st to 53rd Avenue • 54th Avenue, Slade Way to 166th Street • 53rd Avenue, 160th Street to Klickitat Drive • Slade Way, 54th Avenue to 160th Street. Of these, 160th Street from 51st to 53rd Avenue is planned prior to completion of the Valley View Estates project. Most other improvements would be contin- gent on the formation of a Local Improvement District (LID). Portions of .54th Avenue near 166th Street are currently being improved, including widening and curve improvements to eliminate a sharp, narrow curve between 166th and 54th. FORECASTED TRAVEL DEMAND AND TRAFFIC ANALYSIS This section of the report outlines the assumptions and steps used to arrive at an estimate of future traffic demand associated with the Valley View Estates residential development. It discusses the potential impacts of addi- tional automobile and pedestrian traffic on streets in the vicinity of the site, impacts to vehicular and pedestrian safety, and other transportation problems /issues that have been brought to our attention. For the purpose of this project, 1987 was selected as the design year for forecasting traffic. This time frame allows the residential development to be constructed and largely occupied assuming timely approval of the project by the reviewing agency. The forecasted travel demand on streets in the vicinity of the site is composed of three primary elements: (1) existing traffic; (2) future non- project traffic; and (3) forecasted project - generated traffic. Existing traffic volumes are presented in Figure 3 and have been discussed in the Existing Conditions section of this report. Future non - project traffic vol- umes are those volumes which are expected to occur between the present and 1987, but are volumes that have no direct relationship with the occupancy of this project. Project - generated traffic volumes are those volumes that are expected to be generated by the occupants of this project. The sum of these three components results in the total 1987 with - project forecasted traffic volume. Non - Project Traffic Volumes Future non - project traffic is that traffic that would be on the road system regardless of whether the proposed project was constructed. It re- flects growth associated with general development in the area, as well as specific known projects which would be located in the vicinity and generate additional traffic volumes to the roadways. Discussions with City of Tukwila staff indicate that there are no other specific projects in the immediate area which would significantly impact traffic on roadways near the Valley View Estates site. The City of Tukwila Transportation Improvement Plan published in 1979, as well as existing traffic count history in the area were referenced in developing the expected annual traffic growth on roadway links near this project. Based on this research, traffic in the residential area on top of -14- the hill to the west, as well as immediately surrounding the project, is forecasted to grow at about 1 percent compounded annually for the four year period ending in 1987. This reflects the relatively stable neighborhood and its past volume growth history. Traffic volumes along the Pacific Highway S. corridor would be expected to grow at about 2 percent per year compounded annually. To the east, in the Southcenter vicinity, traffic volume growth is forecasted to be significantly higher. The 1979 Transportation Improvement Plan forecasted about 4.5 percent per year traffic growth between 1979 and 1990. However, between 1979 and 1982, traffic volumes have grown between 7 and 18 percent annually. In this area, The TRANSPO Group utilized a 7 percent annual compound growth rate to reflect both the recent high growth trend and the long range, 1990 forecast. Project- Generated Traffic Volumes The TRANSPO Group referred to two nationally and locally accepted standard sources for determining trip generation rates appropriate for application to the proposed Valley View Estates project, Trip Generation Institute of Trans- portation Engineers, 1983, and Trip Generation Intensity Factors, Arizona Department of Transportation, 1979. Trip Generation indicates an average traffic generation rate per dwelling unit (DU) of 6.6 vehicle trip ends (VTE) per DU. Trip Generation Intensity Factors indicates an average rate of 6.8 VTE per DU. A trip generation rate of 8.0 daily VTE per DU was used in this study to reflect both a worst case assumption with regard to potential traffic impacts and to acknowledge the location of the project away from prime transit use areas found closer to downtown Seattle. For the purposes of this study, worst case is defined as the high end of the reasonably expected range of conditions. Corresponding to this daily trip generation rate, a PM peak hour rate of 0.8 VTE per DU was used. This is consistent with numerous observa- tions in residential areas which indicate that approximately 10 percent of the daily travel occurs during the evening peak hour. The above described trip generation rates per dwelling unit were applied to the 108 units proposed for the Valley View Estates residential project. Based on this, The TRANSPO Group estimates that approximately 900 daily ve- hicle trips and 90 evening peak hour vehicle trips would be generated by this project at full occupancy. Traffic Distribution and Assignment The distribution of traffic to and from a residential development is a complex issue. The orientation of the site relative to major streets, the location of both employment and retail centers as well as schools and social/ recreation opportunities are major influencing factors. This distribution of vehicle trips to the Valley View Estates project would be largely influenced by the access pattern created by the surrounding street system. Traffic oriented locally to the west and southwest would generally use S. 158th Street near the site, then using 51st Avenue S. to access other east -west traffic carriers in the residential area west of the project site. The TRANSPO Group estimates that about 38 percent of the daily and 28 percent of the evening peak hour project - generated traffic would orient to these routes. Some traf- fic oriented to the Burien area on the west as well as some oriented to - Pacific Highway S. to the north would use SR 518 via Klickitat Drive as their primary travel route. Klickitat Drive west of 53rd Avenue would also be used by some traffic from southbound I -5 utilizing 52nd and 51st Avenues from Southcenter Boulevard. Approximately 24 percent of the daily and 33 percent of the evening peak hour are oriented to the west on Klickitat Drive. Klickitat Drive east of 53rd Avenue would be used by traffic accessing both north- and southbound I -5, as well as traffic destined for eastbound I -405. In addition, many retail comparison shopping opportunities are located along Southcenter Parkway (Southcenter regional mall, Parkway Plaza, etc). About 34 percent of the daily and 39 percent of the evening peak hour project - generated traffic is oriented east along Klickitat Drive, quickly dispersing along the available travel route options. Figure 6, Project- Generated Traffic Volumes, depicts the daily and evening peak hour traffic volumes associated with the distribution of travel described above on the local roadway system. This traffic assignment illustrates the difference in travel patterns between composite daily traffic and evening peak hour traffic. Evening peak hour traffic assignment is generally more heavily oriented toward routes serving primary employment centers (i.e., Seattle -I -5 N and SR 99 -N, Bellevue /Renton- I- 405E). Daily traffic, in addition to worker - commute trips, reflects social /recreational and retail travel. The daily traffic assignment in Figure 6 therefore reflects travel to and from community PEG 10 Erl EEO 15 100 h PEG 20 10 120 WWI El 160 154TH ST 10 60 NEG NEC 30 10 NEC 30 C.) NEC 80 160TH ST 20 PEG PEG PEG NEC NEC 10 15 300 20 60 20 80 30 220 30 360 25 340 PROJECT SITE NEC 10 20 40 N 1 1 l QD 20 160 30 WEI 164TH ST B3 El m 166TH ST 10 ED E3 NEC NEC m m o- N Ell ECI m NEG 30 110 N m 6. a 170TH ST CO 176TH ST LEGEND: 10 PM PEAK HOUR VOLUMES - DAILY VOLUMES NEG - NEGLIGIBLE 100 NEC 10 178TH ST NEC 20 65 690 15 105 NTF 20 150 25 180 15 5 ®' 80 15 105 ®' SOUTHCENTER MALL 50 10 90 45 0 5 30 m E3 a z z w v 1- STRA10ER 81. VO NEC 20 5 30 PEG PEG PEG 20 180TH ST NEC. 10 a a PEG 10 VALLEY VIEW ESTATES Figure 6 PROJECT-GENERATED TRAFFIC VOLUMES The 'T IANSPO retail centers located at SR 99 and 160th, along Military Road at S. 164th and in the Southcenter /Parkway Plaza vicinity. Traffic volumes associated with each trip purpose were generally assigned to the one or two primary traffic carrying routes between the development and the trip destination. This assignment reflects a worst case traffic volume on these primary traffic - carrying facilities. It is acknowledged that some traffic may use other minor roads in the vicinity (i.e., 164th Street and 166th Street and others); however, these traffic volumes would be very minor and would cause no noticeable increase in either traffic or congestion at intersecting roads. Traffic Analysis Traffic generated by the proposed Valley View Estates project must be evaluated in perspective of the traffic volumes which would likley exist when the project is completed and occupied. As mentioned, 1987 was selected as a design year for the evaluation of traffic conditions. The analysis is a two - step process. First, the forecasted 1987 traffic volume without the proposed project were estimated. Second, the expected traffic volume increases due to the Valley View Estates project were generated and added to yield 1987 volumes with the Valley View Estates development. Project traffic as well as 1987 non - project traffic volumes have been developed in previous sections of this report. Figure 7 depicts the impact of the project traffic on traffic condi- tions likely to exist in 1987, showing both 1987 daily traffic volumes with and without the Valley View Estates project. Traffic volumes, as counted on a day -to -day basis, may vary by + 5 percent for no other reason than the general randomness of trip making characteristics and transportation needs. The following indicates the street system links impacted by the proposed Valley View Estates project which would increase in excess of 5 percent: • 53rd Avenue: 158th Street to Klickitat Drive -- + 530 vpd, + 23 percent • 158th /160th Street: 53rd Avenue to 51st Avenue -- + 340 vpd, + 16 percent • 160th Street: 42nd Avenue to 51st Avenue -- 300 vpd, + 16 percent -18- 27100 27200 J (4000 4030 5000 5030 1900 1910 2400 c ov� 154TH 5T 4300 4380 OEM C11120 160TH ST 10100 10310 1 5600 5600 h` 13800 14020 • )1900 2200 2300 2830 2200 2540 3900 3910 PROJECT SITE 500 11400' 520 1440 26700 26970 400 400 164TH 5T 26100 166TH ST 26120 30700 30730 5600 5610 8500 8500 700 720 117000 117160 36700 36810 NORTH 34100 34210 av 30 N 170TH ST 2000 2010 8800 8840 1300 1350 u_ LL a 176TH 5T 6300 6310 LEGEND: 1000 1100 1987 WITHOUT PROJECT 1987 WITII PROJECT 18200 8220 2000 2050 8200 8210 178TH ST r h ti ®" 14580 30100 30250 SOUTHCENTER MALL 31500 31680 93000 93170 144001' 14400 w w 1- STRMOER 21000 21030 39300 39320 180TH STI VALLEY VIEW ESTATES Figure 7 1987 DAILY TRAFFIC VOLUMES WITH & WITHOUT PROPOSED PROJECT The TTtANSPO • Slade Way /54th Avenue: 170th Street to project -- + 30 vpd, + 15 percent • 170th Street: 51st Avenue to 53rd Avenue -- + 30 vpd, + 6 percent. It should be noted that the 15 percent and 6 percent increases shown for Slade Way, 53rd Avenue S. and 170th Street between 51st Avenue and the project are a result of a total of 30 vehicles assigned to that route on a daily basis. The relatively high percent increases are due to the low traffic volumes currently using these roadways. The 158th /160th Street corridor would be the primary local street artery for traffic destined or originating locally, west of the site, including Pacific Highway S. in Burien. Although the 16 percent in- crease in traffic volumes on this route will be noticeable and could be con- sidered substantial, the roadway is fully capable of comfortably carrying the forecasted traffic both with or without the proposed project. Therefore, we do not anticipate any significant adverse impact associated with these in- creased traffic volumes. 53rd Avenue S. between Klickitat and the project site is expected to increase in volume by 23 percent over 1987 conditions without the proposed project. Again, however, this increase is well within the traffic - carrying, capabilities of the two -lane roadway, and no significant adverse impacts would be anticipated. Typically, 5,000 to 7,000 vpd would be considered desirable maximums for traffic volumes on similarly functioning streets by many jurisdictions. Based on this, most local residential streets which would carry project - generated traffic would operate at less than 50 percent of their generalized "desirable" capacity, with or without the pro- ject. It should be noted, however, that "desirability" varies between neigh- borhoods and depends on many factors including driver expectations and con- flicting pedestrian activity. The location identified in the Existing Conditions section of this report as being a potential problem, 53rd Avenue S. intersecting with Klickitat Drive, would experience no substantial decrease in level of service as a result of project - generated traffic. The critical movement from a congestion standpoint, as calculated using Circular 212 methodology, would be the north- bound left turn from 53rd Avenue S., as mentioned in the Existing Conditions section. This movement would operate in the LOS D range both with and without the proposed project (existing conditions calculations indicated LOS C - operations). The observed westbound left -turn queues which occasionally back -20- up in excess of 7 or 8 vehicles now could become somewhat longer as a result of non - project traffic growth; however, the incremental difference in this queuing situation as a result of this project would generally be unnoticeable. Traffic volumes on Klickitat Drive both east and west of 53rd Avenue S. would be impacted approximately 2 percent as a result of project - generated traffic. This is well within the 5 percent variation observed in daily traffic volumes. The locations of the proposed driveways to the project both off 53rd Avenue S. and Slade Way appear to pose no special problems or concerns rela- tive to either sight distance or traffic volumes. About three - fourths of the total daily project traffic will utilize the northerly driveway along 53rd Avenue S. while about one - fourth will utilize the two driveways along Slade Way. The westerly driveway off Slade Way is a dead end access to 12 of the units, while the easterly driveway is a thru access continuing northward to the 53rd Avenue access point. Safety There do not appear to be any unusual safety hazards associated with the design or siting of the Valley View Estates multi- family housing development, and consequently, the development is not expected to measurably increase the safety hazard potential on most surrounding streets. Traffic accidents in the vicinity may be expected to increase in some proportion to the increase in traffic volumes on streets surrounding the proposed development. However, it is difficult to estimate exactly how large this increase may be. In addition to accidents at nearby intersections increasing at a constant rate, there will be an increased potential for accidents associated with the driveway openings for the development site, due to new turning movement conflicts. Potential conflicting traffic volumes at these locations indicate that the increase would likely be very minor. Although pedestrian traffic along streets in the vicinity has been ob- served to be very light, there would be an increased potential for vehicle - pedestrian conflicts along these roadways. The contribution of project traf- fic along most roadways in the neighborhoods to the west and south would be very small, however, and therefore the fraction of the small potential increase in accidents attributable to the project - generated traffic would generally be unnoticeably small. Parking A total of 162 parking spaces are currently to be supplied on -site. This indicates a ratio of 1.5 spaces per dwelling unit, which is consistent with section 18.56 of the zoning code under which this project will be reviewed. The proposed parking supply and its layout should be adequate to contain "everyday" residential parking demand completely on -site. We would not•antic- ipate any residential parking spillover to 53rd Avenue S., Klickitat Drive or Slade Way. There may be a few days during the year when some overflow parking may be required due to social activities generating extraordinary visitor parking demand. The site plan indicates that there are some areas on -site which could be designed to accommodate overflow parking should it be required. Up to 20 vehicles would appear to be potentially accommodated in the area designated RMH on the current project site plan (not shown in this document). Allowing for some on -site overflow in the site design would help ensure that project parking demand would not noticeably impact Slade Way or 53rd Avenue S., even during peak demand periods. Transit Although, in order to reflect a worst case traffic impact analysis, all trips were assumed to occur via auto, it is acknowledged that a certain small percentage of the trips to the project site would arrive by transit. Since one transit route passes by the site along 53rd Avenue and others are acces- sible nearby in the Southcenter vicinity, it would be expected that some riders may find it convenient to utilize this mode. It is estimated that less than 5 percent of the total trips to and from the Valley View projects would be made by transit patrons. This would indicate that no more than 50 daily trips (25 arrivals, 25 departures) would be made by transit users. Metro Transit would likely view this impact as positive rather than adverse. Pedestrian and Bicycle Travel A small percentage of the total travel associated with the Valley View Estates residential development would be expected to be generated by pedes- trians or bicyclists. Its relative isolation from any designated pedestrian or bicycle facilities would tend to discourage this type of travel for most trip purposes. The expected level of increased activity of both pedestrian and bicycle travel associated with the Valley View Estates project should not result in significant adverse impacts. However, since there would be some increase in this activity, there would be a corresponding increase in the potential for vehicle - pedestrians and vehicle - bicyclists conflicts and there- fore some potential for increased accidents. Construction Impacts There will be additional truck traffic generated by the project site during the construction period, particularly during the early stages of exca- vation. However, the size of this construction project, coupled with the fact that these truck trips are generally spread evenly throughout the work day, indicate that impacts will generally be unnoticeable to all but a few neigh- bors abutting the site directly to the west. While the overall construction period may last about one year, period of maximum excavation should not last for more than a few weeks. CONCLUSIONS AND MITIGATING MEASURES This section of the report summarizes the conclusions of this traffic analysis, and suggests physical improvements and /or policy actions that would help ensure forecasted conditions are achieved and any identified impacts minimized. As a result of the proposed Valley View Estates residential development, approximately 900 daily vehicle trips will be added to the adjacent street system under a worst case traffic analysis. By 1987, net new project volumes would increase adjacent street traffic volumes between 15 and 23 percent; however, these impacts quickly dissipate to less than 5 percent within a few blocks of the project site. Traffic congestion at the nearby intersection of 53rd Avenue S. and Klickitat Drive will increase slightly as a result of the proposed project during the evening peak hour; however, safety improvements at the intersection (see recommendation below) would be desirable immediately as well as in 1987 with or without the project. Transit ridership and pedestrian activity could potentially increase due to this project; however, the degree of the increase would likely be insignif- icant. The location of the project, nearby terrain, and the lack of any formal pedestrian or bicycle facilities would not promote significant use by these modes. To help ensure that traffic impacts are minimized, the following mitigating actions are recommended. • A left -turn lane for westbound -to- southbound left turns from Klickitat Drive to 53rd Avenue S. would be desirable to eliminate conflicts between left- turning traffic and westbound thru traffic. Traffic accident experience over the last three years shows a consist- ent pattern of rear -end accidents at this location which would be addressed and reduced significantly by such an improvement. This improvement would be considered desirable to improve existing inter- section operation as well as in the future with or without the pro- ject. Project - generated traffic will add about 2 percent additional traffic on this intersection approach, both daily and during the peak hour; however, it will increase the left -turn component of this ap- proach volume about 25 percent. • Work with Metro Transit to ensure a safe, convenient bus stop location for project transit patrons adjacent to the Valley View Estates site. • Assure that project driveway locations are at least 150 feet away from the nearest intersection. The most current site plan available indi- cates that this condition is met by the current design. -24- • Provide on -site parking overflow areas to accommodate infrequent parking demand conditions in excess of 1.5 per dwelling unit. There appears to be capacity for about 20 vehicles in the area designated RMH in the western portion of the site adjacent to 53rd Avenue. • Do not allow parking spaces on -site to be reserved for any particular residential unit. This will allow flexibility to accommodate fluct- uating demands in the primary designated parking areas. • Parking of recreational vehicles or trailers should be accommodated off -site to ensure the residential and visitor parking flexibility is maintained. Appendix F Utilities Study VALLEY VIEW Prepared By: STEPAN & ASSOCIATES, INC. 930 SOUTH 336TH STREET FEDERAL WAY, WASHINGTON 98003 DECEMBER 1983 WATER H tit OF F /ABS ORP i' ON EXISTING CONDITIONS The U.S. Department of Agriculture, Soil Convervation Service (1973) reports that the native site soil is Alderwood sandy loam. In soils of this classification permeability is moderately rapid in the surface layer and subsoil and very slow in the substratum. Water moves on top of the substratum in winter. Impacts: Existing runoff and absorption characteristics would be altered by two aspects of the proposed development: removal of remaining vegetation during site preparation, and introduction of impervious surfaces on the site in the fo nn of roads, parking areas, and structures. Absorption would be reduced, and the rate and volume of runoff would be increased. The proposed stormwater collection and detention system (see proposed site utility plan) would reduce the potential for adverse off -site impacts from runoff by controlling the rate of release to that which occurs under existing conditions. The length of time over which peak discharge would occur would be prolonged. Mitigating Measures: The proposed stormwater detention facilities and controlled discharge devices would mitigate the impacts of site development on runoff and absorption characteristics in accordance with City of Tukwila requirements. SURFACE WATER MOVEMENT AND QUANTITY Existing Conditions: The drainage basin is bounded by Slade Way and the extension of 158th Street on the north. The basin area is 7.2 acres and is divided into 2 sub basins the south being 4.4 acres and the north 2.8 acres. There is a 15 inch storm sewer that intercepts drainage from the acres east of Slade Way and transports it to an existing deep storm system that was installed during the contruction of I -5. The 15 inch storm sewer runs above ground part of the way and is leaking (observation 10/17/83) causing some ponding in the immediate area. The deep system consists of perforated drain pipe and runs generally in a north -south direction and terminates on site as shown on the site utility plan. Very little flow was observed in the portion of the perforated pipe system upstream of the point that the 15 inch culvert intersects the deep system during a site visit 10/17/83. The manhole grates were raised and the system inspected during this visit. Surface runoff from the site sheet flows to a lined ditch just east of the site which is shown on the site utility plan. This ditch discharges to the existing deep storm system downstream of the site as shown on the site utility plan. Impacts: Construction of the proposed development would not alter existing drainage basin boudaries, nor would it add to the peak flow of stormwater runoff received by the storm system east of the site, however, it would alter existing on -site surface water movement due to moderate re- grading. Surface water would be collected in a subsurface conduit system as shown on the site utility plan, which would direct stormwater drainage at higher velocities and in slightly different directions across the site.. The 7.2 acre drainage basin is divided into 2 sub basins the south being 4.4 acres and the north 2.8 acres. The porposed drainage system includes storm drainage retention pipes and control structures which would control and store storm water to limit the runoff rate to a predevelopment rate. Therefore, surface water would exit the "site at approximately the same rate as it does under existing conditions. Based on a storm of 10 year recurrence interval, sub -basin "A" would require approximately 1,500 cu. ft. of storage capacity, and that sub -basin "B" would require approximately 1,000 cu. ft. of storage. The size of the controlled outlet from the site would be calculated for the total on -site drainage basin to release runoff at a rate that would not exceed existing conditions. A11 required stormwater detention facilities would be constructed and in operation prior to paving and building construction. A portion of the existing perforated deep storm system would be abandoned (see appendix- Letter from Department of Transportation) and replaced by a new storm line to handle offsite runoff as shown on the site utility plan. The existing storm line that is above ground and leaking would be repaired. Mitigating Measures: A stormwater detention system designed for a 10 year storm capable of detaining 2,•500 cubic feet of water is proposed to be installed. Stormwater will be stored in oversized pipes. 'The gravity flow system is designed to discharge stormwater at the same rate as the existing discharge rate. The City of Tukwila must approve stormwater drainage plans prior to issuance of the building permit. A temporary storm management system and the erosion control measures will be employed during construction. Where possible, natural vegetation for silt control shall be maintained. Temporary siltation and detention ponds shall be constructed by placing straw bales across swales. All temporary siltation ponds shall be maintained in a satisfactory condition until such time as cleaning and /or construction is completed and permanent drainage facilities are operational. Rip -rap base (both sides) of bales shall be positioned as required for erosion control. Cleaning of streets and parking areas shall be undertaken whenever necessary and frequent maintenance of the stormwater system shall be provided. Surface Water Quality Existing Conditions: There is no known water quality data for surface runoff from the site. Impacts: The introduction of impervious surfaces over a portion of the proposed development would reduce the area of exposed soils. Therefore, reduced quantities of sediment, nutrients, organic material, and possibly arsenic and cadmium particles contained in the soil would be expected to leave the site in surface runoff. However, in place of these would be contaminants more typical of residential developments: petroleum residues, traces of heavy metals, and sediments washed from roads and driveways. The increased quantity of impervious surfaces would increase the volume of stormwater runoff from the site, and thus may carry these pollutants in a more dilute concentration. Catch basins and oil /water separators proposed within the on -site drainage collection system would function to separate sediments and petroleum residues from stormwater to a certain extent. On -site drainage detention and the outlet control structure would further allow for separation of these pollutants from storm water before release from the site. Use of pesticides, herbicides, and fertilizers (if any) on yards and on landscaping in common .areas may occasionally contribute slight quantities of contaminants to storm - water that would not be removed by the proposed pollution separation devices. Also, the partial coverage of soils with asphalt paving and structures may result in slight elevation of temperature of runoff from these surfaces. Perhaps the most significant potential for adverse impact on surface water quality would be during temporary construction periods. Clearing and grading would expose soils on the site to potential erosion by rainfall. Site runoff could carry a significant sediment load if heavy or prolonged rainfall occurred during the early stages of developement. Proposed interim drainage control measures include placing strawbales in drainage ditches and directing runoff to two intermim detention ponds to be constructed of strawbales or filter fabric. Mitigating Measures: The proponent would have maintenance responsibility for the drainage control facilities during construction, and it is proposed that the owner assume maintenance responsibility for these facilities after completion of the development. Catch basins and oil /water separators should be cleaned frequently and properly maintained to assure maximum attainable pollution separation. Groundwater Existing Conditions: Impacts: Due to the proposed introduction of paved areas and structures on the site, it is likely. that direct surface runoff would increase and direct infiltration into the ground surface would decrease. It could be expected that lawn areas and landscaping, which would be periodically watered (particularly during dry weather), would introduce additional water to groundwater resources. The total contribution of the site itself to the groundwater supply is probably very small (although detailed investigations have not been conducted to define the extent of the groundwater basin). Although it is not possible to accurately predict the overall impact of the development on groundwater quantity, it is the opinion of the geotechnical consultant that, based on the above considerations, the impact would be minimal. Mitigating Measures: To mitigate potential impacts on the project from groundwater, the applicant proposes to comply with the recommendations of the geotechnical consultant. Pavements would slope down and away from the buildings in all directions to the storm drainage collection system. Conventional design and construction procedures should be adequate for roadway and parking area pavements to be developed on compacted soil Water System Existing Conditions: The project is located near the boundary of the Water District #75 and City of Tukwila service areas. The project is actually in the Water Districts 75 service area but would be served from the City of Tukwila pressure reducing station on 53rd Avenue South as shown on the site utility plan. This would necessitate a service area agreement with the two Districts or a deannexation from the Water District 75 area. Impacts: The City's water distribution system would be extended to serve the site as shown on the site utility plan with proposed connections to the existing pressure reducing station at 53rd Avenue South, and fire hydrants spaced as required to provide adequate fire protection. The water system . within the development would be designed by the proponent's engineer and constructed within the private road rights -of -way. It would be dedicated to the City, and an easement would be granted for access to maintain the system. The proposed system would connect to the pressure reducing station in 53rd Avenue South. This station connects to the existing Cedar River Pipeline #4. Static pressure at fire hydrant No. 112 which is located downstream and to the north of the pressure reducing station was recorded at 69 psi. According to the Tukwila Water Department (David Grage) the static pressure has been increased to approximately 85 psi since that reading was taken. Fire flow should not be a problem in this area according to the City of Tukwila Fire Department (Jim Hole) because the site and pressure reducing station are located so close to the large Cedar River pipe line, required fire flow would be approximately 2100 gpm (see appendix for calculations) based on the site plan and building type. Installation of the water system to serve the proposed development could have short -term impacts on vehicular travel at the intersections of S. 158th Street with 53rd Avenue South if trenching were required within the right - of-way or across the road. During actual connection of the project system to the City system, water service in the area could be interrupted for brief periods of time. Implementation of the proposal would result in a long -term commitment of the City water supply to serve the proposed development; however, as stated above, the City does not expect to experience difficulty in meeting long range demands in the area. The proposed on -site system would comply with City of Tukwila fire flow and hydrant - spacing requirements, as well as with the requirements of the Washington State Department of Social and Health Services. According to Washington Survey and Rating Bureau criteria, approximately 2100 gpm (see appendix for calculations) is the required fire flow for multi - family developments of this type. The proposed system would meet the minimum criteria. Projected domestic water usage for the site should not exceed 0.04 mgd on a peak day (see appendix for calculations). As mentioned above, a service area agreement between the City of Tukwila and Water District 75 or deannexation from Water District 75 is required to serve the project from the City of Tukwila water system. Mitigating Measures: Installation of water - saving fixtures and devices such as flow restrictors in new dwelling units (at the discretion of the builder) could reduce water consumption, if such measures are determined to be necessary or desirable. SANITARY SEWER SYSTEM Existing Condition: The site would be served by Val Vue sewer district. There is an existing 12 inch cast iron sewage main which runs through the site as shown on the utility site plan. The line connects to Metro at the Val Vue connection. Sewage from the site would be treated at the Renton Sewage Treatment Plant and would be transmitted to the plant via the Interurban Pump Station, Freeway Interceptor and Tukwila Interceptor'. The proposed project is within Metro's Renton treatment plant service area. Metro has prepared a facilities plan for the Renton system with a grant from DOE and EPA, in part because the Renton treatment plant has reached its "design" capacity and continued development is occurring within the service area. A final plan for the Renton service area was adopted by the Metro Council in November 1981 and contains a recommended program for upgrading the Renton system so that water quality and health will continue to be protected. The plan calls for these improvements to be on line in the s uiuner of 1986. Impact: The on -site sewage collection system would be designed by the proponent's engineer and would be installed as shown on the site utility plan. Six and eight inch lines would collect sewage throughout the project and connect into the existing Val Vue sewer line as shown. • Portions of the existing 12 inch cast iron main would be underneath proposed furture building locations. The existing 12 inch line could be cased in. a larger carrier pipe where it is underneath these proposed buildings to provide for future maintenance. The development will result in increased sewage flows. As stated above, the Renton Treatment Plant is currently treating more than design capacity but temporary measures are being taken which will accommodate flows. The plant will be upgraded in 1986 if present plans are implemented. Mitigating Measures: If water use were reduced by residents implementing water- saving measures in their homes, the volume of sewage that would be discharged from the project area would also be reduced. SOILD WASTE Existing Consitions: The business and residences in the surrounding vicinity are currently served by Sea -Tac Disposal. Dumpsters and compactors can be rented from them. The solid waste is taken to the King County Transfer Station. Impacts: The proposed development will increase demand for solid waste collection which can adequately be provided by Sea -Tac Disposal. Mitigating Measures: None. APPENDIX VALLEY VIEW ESTATES Preliminary Storm Drainage Analysis Storm Drainage Criteria The storm drainage system for the proposed project as previously described shall be based upon the following criteria. These criteria and method of analysis are quoted from the 'Requirements and Guidelines for Storm Drainage Control in King County', Division of Hydraulics, King County, May 1979 and that document should be referenced for additional information. 1. Runoff Rate Q = CIA where Q = Rate of flow in cubic feet/second C = Runoff co- efficient based on relative imperviousness of the area i = Rainfall intensity in inches/hour for Seattle area based on 10 year re- occurrence interval A = Area of runoff in acres 2. .Time of Runoff Concentration shall include 10 minutes initial collection time in unpaved areas and 5 minutes in paved areas. 3. Runoff storage volume will be based on the following equations: Vs = 2820 T T5 - 40 QoT T = 25 + 1762 Qo Qo = Q EXISTING Area X Developed Runoff Coef. Procedures accpeted by the City of Tukwila Public Works Department have been used to determine the storage volume required. Calculation of drainage pipes, ditches and other facilities will be completed, based on requirements with design of the final facilities. Basin A (See Site Utility Plan) Area in basin = 4.4 acres Travel length = 500 feet Velocity (slope average 258) = 1.3 FPS (bare ground) Travel Time = 10 + 500 1.3(60) i10 = 1.25 inch/min. (Seattle = 16.4 minutes "c" =.15 existing Existing 10 year peak rate = Q = CiA = (.15) (1.25) (4.4) =0.83 cfs existing C = 2.1 ac (0.90) + 5.0 ac (.15) = 0.37 Future 7.1 Q = existing = 0.83 = 0.51 o Area ( "c "future) 4.4(0.37) T = -25 + 1763 = 34 minutes 0.51 V s 2820(34) - 40(0.51) 34 = 931 ft. 3 /Acre s 25 + 34 ( "c" future). VT = 931 (4.4)(.37) = 1516 ft 3 Basin B Area in basin = 2.8 acres Travel length = 500 feet Velocity (slope average 25 %) Travel Time = 10 + 500 = i25 1.25 inch/min. (Seattle) = 1.3 fps 16.4 minutes "c" existing = •15 Existing 10 year peak rate = Qexisting = CiA = (0.15)(1.25)(2.8) = 0.53cfs Cfuture = 2.1(0.9) + 5(1.5) = 0.37 7.1 0,0 = • Qexisting = .53 = 0.51 Area ( "c future) 2.8(.37) T = -25 + 1762 = 34 minutes 0.51 Vs = 2820(34) - 40(0.51)34 = 931 ft.3 /Acre ( "c "existing) 25 +34 3 VT = 431(2.8).37 = 965 ft. Fire Flow Requirements F= 18 C(A)0.5 * C= 1.5 Wood Frame Construction 5,248 Square Feet F= 18 (1.5(5248) 0.5 = 1,956 gpm use 2,000 gpm Less 25% (low hazard occupancy) -500 1,500 Plus Exposures (20% + 20 %) =40% = +600 2,100 gpm Projected Water Usage Multi Family - 90 gal /unit -day Peaking Factor = 18 + p P- poulation in thousands 4 +p P = 18 + 0.216 = 4.14 4 + 0.216 Flow = 90 gal /unity -day x 108 units x 4.14 = 0.04 million gallons per day 1,000,000 gal /mg * Guide for determination of required fire flow; Insurance Service Office Sanitary Sewer Flow Multi- Family 90 gal /unit -day Infiltration Inflow = 1,100 gal /ac -day; 7.2 acres Peaking factor = 18 + P = 4.14 TT Flow = 90x108x4.14 + 1,100 x7.2 = 0.05 million gallons per day 1,000,000 ' # le 0 -8� FINAL ENVIRONMENTAL IMPACT STATEMENT VALLEY VIEW ESTATES CITY OF TUKWILA PLANNING DEPARTMENT January 1986 AFFIDAVIT C1 Notice of Public Hearing [l Notice of Public Meeting [� Board of Adjustment Agenda Packet [l Board of Appeals Agenda Packet [� Planning Commission Agenda Packet El Short Subdivision Agenda Packet [l Notice of Application for Shoreline Management Permit [[ Shoreline Management Permit OF DISTRIBUTION hereby declare that: [[ Determination of Nonsignificance 0 Mitigated Determination of Non - significance [[ Determination of Significance and Scoping Notice [[ Notice of Action Q Official Notice L "other FE1S D Other was mailed to each of the following addresses on Environmental Evaluation Branch EPA Attn: Ms. Lisa Corbyn, Director 1200 6th Avenue, MS 443 Seattle, WA 98101 Environmental Protection Agency Attn: Mr. Walt Jaspers Director of Federal Affairs 1200 6th Avenue, MS 623 Seattle, WA 98101 U.S. Army Corps of Engineers Attn: Col. Leon Moraski Seattle District NPSEN -PL -RP P.O. Box C3755 Seattle, WA 98124 Environmental Review Section Attn: Ms. Debbie Kneeland Department of Ecology, MSPV -11 Olympia, WA 98504 Washington State Department of Ecology Attn: Mr. Stan Springer, Head. Environmental Review St. Martin's College Campus Lacey, WA 98504 Name of Project VC 1 -31- g(a , 19 . Washington State Dept. of-Transportation Attn: Mr. Bernie Chaplin Environmental Planner Highway Administration Building, MS KF -01 Olympia, WA 98504 Mr. R. F. Johnson, P.E. Dept. of Transportation District Engineer, District #1 6431 Corson Ave South Seattle, WA 98108 Highline Times P.O. Box 518 Seattle, WA 98166 Renton Record Chronicle Attn: Real Estate /Urban Affairs 212 Wells Ave. So., #101 Renton, WA 98055 Tukwila Library 14475 59th Street Tukwila, WA 98188 Valley View Library 17850 Military Road South Seattle, WA 98188 (over) \( uLO qtr iii Q ,tft71,,,IcY0 File Number Signature Larry Hard (delivered by hand) Puget Western Development Thomas W. Russell P.O. Box 97034 Bellevue, WA 98009 -9734 Joel Haggard Ann Scales LandUse Consultant 4301 2nd Avenue N.E. Seattle, WA 98105 Dames & Moore Geotechnical Engineers 155 N.E. 100th Street Seattle, WA 98125 AFFIDAVIT 0. [l Notice of Public Hearing O Notice of Public Meeting OF DISTRIBUTION 00 hereby declare that: [j Board of Adjustment Agenda Packet Board of Appeals Agenda Packet O Planning Commission Agenda Packet [J Short Subdivision Agenda Packet 0 Notice of Application for Shoreline Management Permit [l Shoreline Management Permit [] Determination of Nonsignificance Q Mitigated Determination of Non - significance O Determination of Significance and Scoping Notice 0 Notice of Action [[ Official Notice ErOther FE /S 0 Other was mailed to each of the following addresses on JthJ(,(,(Cc,2,c c j /6/V0 , 19 . Tom Russell (4 copies: GeoEngineers, Stepan & Associates, Mithun Group, and Russell) Land Planner P.O. Box 97034 Bellevue, WA 98005 -9734 Name of Project File Number .zitaziko AFFIDAVIT OF DISTRIBUTION I, xat-kueu a hereby declare that: [D Notice of Public Hearing [� Notice of Public Meeting [[ Board of Adjustment Agenda Packet Ei Board of Appeals Agenda Packet [j Planning Commission Agenda Packet [[ Short Subdivision Agenda Packet [� Notice of Application for Shoreline Management Permit [� Shoreline Management Permit [D Other (l Determination of Nonsignificance [] Mitigated Determination of Non - significance [] Determination of Significance and Scoping Notice [11 Notice of Action [[ Official Notice [Other FE/ S was mailed to each of the following addresses on See attached sheets Name of Project V" I/ / 4410I2/ File Number , 19 . Office of Community Planning & Development Attn: Mr. Charles Bickley, Director Department of Housing and Urban Development Arcade Plaza Building, MS 427 Seattle, WA 98101 Department of Energy Attn: Ms. Nan Evans Room 1992, Federal Building 915 Second Avenue Seattle, WA 98104 United States Geological Survey 1201 Pacific Avenue, Suite 600 Tacoma, Wa 98402 Washington State Department of Game Habitat Management Division Attn: Mr. Bob Zeigler 600 North Capitol Way Olympia, Wa 98504 Washington State Department of Natura Attn: Mr. Harry Anderson Public Land Building, MS EX -11 Olympia, WA 98504 Washington State Historic Pres, Attn: Ms. Jeanne M. Welch, Di 111 W. 21st Ave., MS KL -11 Olympia, WA 98504 Office of Public Archaeology University of Washi - ^ *'n Attn: Mr. Jerry Jermann, Dir 213 Engineering Annex, FM -12 Seattle, WA 98195 Environmental Planning Division Attn: Rodney G. Proctor, Manager Metro, MS 63 821 Second Avenue Seattle, WA 98104 Metro - Sewerage 1200 Monster Road SW Renton, WA 98055 Metro - Transit 821 Second Seattle, WA 98101 Puget Sound Air Pollution Control Agency Attn: Mr. A. R. Dammkoehler Air Pollution Control Officer P.O. Box 9863 Seattle, WA 98109 Puget Sound Council of Governments 216 First Avenue South Seattle, WA 98104 Seattle /King County Commuter Pool Program Attn: Mr. William T. Roach, Program Manager Arctic Building, Room 600 704 Third Avenue Seattle, WA 98104 Local Agencies Auburn Planning Department 25 West Main Auburn, WA 98002 Des Moines Planning Department 21630 11th Avenue South Des Moines, WA 98188 Kent Planning Department 220 South 4th Street Kent, WA 98032 Bob Grieve King County Council 4th Floor /King County Courthouse Seattle, WA 98104 King County Dept of Public Works Surface Water Mangement Attn: Mr. George Wannamaker, Director 969 King County Administration Building Seattle, WA 98104 King County Dept of Budget & Program Development EIS Review 400 King County Courthouse Seattle, WA 98104 King County Drainage Dristrict #1 Attn: Mr. Jack Nelson 25403 104th Ave SE #3 Kent, WA 98031 King County Department of Community Development Building and Land Development 410 King County Administration Building Seattle, Wa 98104 King County Dept of Planning & Community Development Planning Division W217 King County Courhouse Seattle, WA 98104 King County Soil and Water Conservation Service 35 S. Grady Way Renton, WA 98055 Renton Planning Department 200 Mill Street Renton, WA 98055 Seattle Water Department 821 2nd Avenue Seattle, WA 98104 Val -Vue Sewer District P.O. Box 68063 Seattle, WA 98168 King County Water District No. 75. P.O. Box 68100 Seattle, WA 98168 King County Fire District 18 4237 South 144th Seattle, WA 98168 King County Fire District 24 2929 South 200th Seattle, WA 98188 City of Tukwila Mayor City Administrator City Council (7 copies) Planning Commission (7 copies) Public Works Department Parks and Recreation Department Police Department Fire Department City Attorney Building Division SEPA Information Center Utilities /Services South Central School District #406 4640 South 144th Seattle, WA 98168 Highline School District #401 15675 Amboum Boulevard S.W. Seattle, WA 98166 Puget Sound Power and Light Attn: Mr. Dick Causey Puget Power Building Bellevue, WA 98009 Washington Natural Gas Company 815 Mercer Seattle, WA 98109 Pacific Northwest Bell 107 N. Division Auburn, WA 98002 Newspapers and Libraries Kent News Journal Attn: EIS Review P.O. Box 130 Kent, WA 98031 Seattle Times Fairview & John Seattle, WA 98121 South Seattle Times 6000 Southcenter Blvd., Suite 220 Tukwila, WA 98188 - -- Seattle Post - Intelligencer 6th & Wall Seattle, WA 98121 Daily Journal of Commerce' 83 Columbia Seattle, WA 98104 Private Organizations and Others Washington Environmental Council 107 South Main Seattle, WA 98104 Tukwila /SeaTac Chamber of Commerce 950 Andover Park East Tukwila, WA 98188 Green River Study Group Attn: Ms. Carol Stoner P.O. Box 775 Kent, WA '98031 Rainier Audubon Society Conservation Committee Attn: Mr. Keith Bechard P.O. Box 778 Auburn, WA 98002 Neighborhood Residents Mr. Alfred Schmid 1525 Taylor Ave. N. #101 Seattle, WA 98109 Bel Crest Realty, Inc. 12431 Kingsgate Way NE Kirkland, Wa 98033 Mr. Robert C. Christensen 16241 54th Ave S Seattle, WA 98188 Mr. Heinz Ritter 5213 S 164th Seattle, WA 98188 Mr. Jack R. Nyholm 5215 S 164th Seattle, WA 98188 Mr. Patrick Mitchell 16227 54th Ave S Seattle, WA 98188 Mr. Thomas C. Johanson 16231 54th Ave S Seattle, WA 98188 Ms. Ruby A. Mitchell Mr. John D. Mitchell P.O. Box 68015 Seattle, WA 98188 Mr. Gerard A. McElholm 5156 S 160th LSt. Seattle, WA 98188 Mr..Godon M. Solem 5155 S 160th Seattle, WA 98188 M.D. Shawley 15811 53rd S Seattle, WA 98168 J. L. Barnes 15814 51st Ave S Seattle, WA 98188 Mr & Mrs. W. Lester Warehine 12016 26th Ave S Seattle, WA 98188 McNamara Investment Co., Inc. 1600 Dexter Ave N, Suite #1 Seattle, WA 98109 Mr. John Y. Back 4439 S 170th Seattle, WA 98188 Mr. Raymond Nielson 5108 S 163rd P1 Seattle, WA 98188 Mr. Calvin M. Johnson 5110 S 163rd P1 Seattle, WA 98188 Mr. Richard A. Goe 5112 S 163rd P1 Seattle, WA 98188 Mr. Steven Welsh 5113 S 163rd P1 Seattle, WA 98188 Mr. Robert T. Amundson 5111 S 163rd P1 Seattle, WA 98188 Mr. David E. Yankee 5109 S 163rd P1 Seattle, WA 98188 Mr. James F. Rial 16243 52nd Ave S Seattle, WA 98188 Mr. John E. Schwarzmann 16251 52nd Ave S Seattle, WA 98188 R. H. Small 16244 52nd Ave S Seattle, WA 98188 Mr. Herbert W. Phalan 16250 52nd Ave S Seattle, WA- 98188 Mr. Edgar 0. Bauch 16603 53rd S Seattle, WA 98188 Mr. Robert L. Crain 5105 S 163rd P1 Seattle, WA 98188 Mr. Hans B. West 5212 S 164th Seattle, WA 98188 Mr. & Mrs. Richard McLester 5118 S 164th Tukwila, WA 98188 Mr. & Mrs. Leo Sowinski 16050 51st Ave. S Tukwila, WA 98188 Mr. & Mrs. Dennis. Robinson 16038 48th Ave S Seattle, WA 98188 John Barnes 15828 51st Ave S Tukwila, WA 98188 Bernie Onorati 5102 S 163rd P1 Tukwila, WA 98188 Mrs. Ethel Mae Cole 16030 51st Ave S. Tukwila, WA 98188 Al Pieper 17083 53rd Ave S Tukwila, WA 98188 Fred Bigelow 5207 S. 164th Tukwila, WA 98188 Louis Hayes 16634 53rd Avenue South Tukwila, WA 98188 City of Tukwila 6200 Southcenter Boulevard Tukwila Washington 98188 TO: FROM: DATE: SUBJECT: MEMORANDUM All Interested Parties Bradley J. Collins January 31, 1986 Availability of Valley View Estates Final EIS The final Environmental Impact Statement for the proposed Valley View Estates development is being issued on January 31, 1986. Valley View Estates is a 108 -unit multi - family residential development proposed for a seven acre hillside site west of I -5 and bordered by Slade Way and 53rd Avenue South. This FEIS document is divided into three parts: Part One: A revised Environmental Impact Statement clarifying and expanding on major environmental impacts of the project described in the Draft EIS issued December 28, 1985. Part Two: Comments and responses to comments on the adequacy of the Draft EIS submitted in writing during the 30 -day comment period or presented at the public hearing for the project held on January 22, 1985. Part Three: Appendices, revised geotechnical and utilities reports (originally Appendices A and G in the Draft EIS). Other appendices that are referenced in the revised EIS, but have not been changed from the Draft EIS are not reprinted herein. The Draft EIS including these other appendices is available for public review at the City of Tukwila Planning Department, Tukwila Public Library and the King County Valley View Public Library. The Environmental Impact Statement for the Valley View Estates development has been revised in response to agency and individual comments. The focus of this effort has been to provide greater detail on the geology and hydrology characteristics of the site, the probable impacts of the project on these conditions and measures that could be implemented to reduce or eliminate these impacts. A critical element of the site is the hazard posed by steep slopes and subsurface geological and groundwater conditions that could contribute to both near - surface and deep- seated landslides. Because of previous measures undertaken by Washington State Department of Transportation to encourage groundwater drainage to promote stability of the hillside, the geotechnical study determined that development of the project was feasible if measures are undertaken to assure the operational Valley View Estates Final EIS January 31, 1986 Page 2 effectiveness of the DOT facilities thereby promoting hillside stability. The study outlines a number of measures that are necessary to reduce or overcome site geological hazards. The revised EIS also addresses the noise characteristics and associated health hazards in greater detail than the Draft EIS. A number of measures are discussed that could be implemented to reduce adverse noise conditions. In issuing the Final EIS, the City has accepted the document and associated studies as satisfying the SEPA requirements of the Valley View Estates pro- ject. The EIS provides the basis for subsequent city actions with respect to the proposed project. The State Environmental Policy Act (SEPA) allows the City to implement mitigating measures to reduce or eliminate identified adverse environmental impacts of the project as conditions of any approved City permit. The City could also deny the permit based on any significant, unavoidable adverse impacts that cannot be mitigated. No City action on the project can be taken until at least seven days after the issuance of the FEIS. Any party who wishes to challenge the document adequacy under SEPA or the City's substantive authority to condition the project under SEPA, can do so only after the City has taken the first action in approving or denying a permit for the project. The first action the City will take on the Valley View Estates project will be the Board of Architectural Review's approval or denial of the site plan. This action by the BAR is not anticipated before March 27, 1986. Once the BAR has acted on the per- mit and the City has published notice of this action, any party has 30 days from the time of the Notice of Action to appeal the action under SEPA. The appeal would be filed at City Hall and would be heard by the Tukwila City Council. Once City Council has acted on the appeal, this action could be challenged in King County Superior Court. (EIS.M) PART ONE REVISED ENVIRONMENTAL IMPACT STATEMENT FINAL ENVIRONMENTAL IMPACT STATEMENT FOR VALLEY VIEW ESTATES PREPARED UNDER THE DIRECTION OF CITY OF TUKWILA PLANNING DEPARTMENT TUKWILA, WASHINGTON Prepared in Compliance. with The State Environmental Policy Act of 1971 Chapter 43.21c, Revised Code of Washington, as amended SEPA Guidelines, Effective January 16, 1976 Chapter 197 -10, Washington Administrative Code, as revised January 31, 1985 City of Tukwila Ordinance Number 1211 1984 Bradley J. C Responsible Off' 1 a1 TABLE OF CONTENTS Part One Revised Environmental Impact Statement Page # Fact Sheet v Distribution List xi I. Summary 1 A. Summary of the Proposal 1 B. Summary of Potential and Indirect Environmental Impacts 1 C. Alternatives 8 D. Summary of Mitigating Measures 11 E. Unavoidable Adverse Impacts 21 II. Description of the Proposal 25 A. Name of Proposal 25 B. Project Sponsor 25 C. Project Location 25 0. City of Tukwila File Number 25 E. Site Description 25 F. Description of the Surrounding Area 25 G. Major Physical and Engineering Aspects of the. Proposal 25 H. Relationship to Existing Laws, Plans and Policies 27 I. Proponent's Objectives for the Proposal 48 III. Existing Conditions, Impacts and Mtigating Measures 49 A. Index of Elements of the Environment 49 B. Elements of the Physical Environment 51 C. Elements of the Human Environment 94 1V. Unavoidable Adverse Impacts 136 V. Short Term Use vs. Long Term Productivity 138 VI. Irreversible and Irretrievable Commitment of Resources 139 VII. Alternatives to the Proposal 140 Part Two Comments and Responses Page # Department of the Army, Corps of Engineers 145 State Department of Transportation, January 28, 1985 149 State Department of Transportation, March 19, 1985 151 State Department of Ecology 153 State Office of Archaeology and Historic Preservation 155 King County Department of Planning 157 City of Auburn 161 Puget Sound Air Pollution Control Agency 163 Metro 165 Water District No. 75 169 Seattle Water Department 173 Val Vue Sewer District 175 Law firm of Jensen and Black 179 Joel Haggard, Attorney 185 Dames & Moore (not attached) 195 Fred Bigelow 213 Robert Crain and Richard Goe 217 Barbara Welsh Griffin 227 Ethylmae Cole 231 Mildred Heppenstall 233 Mikell Goe 235 Ruth Hays 243 Elizabeth Dohms 245 Tukwila /McMicken Action Committee 247 Public Hearing, January 22, 1985 253 Part Three Appendices A. Geotechnical and Hydrological Studies B. Utility Study LIST OF FIGURES AND TABLES Figures Page # 1. Location of Site vi 2. Aerial Photograph vii 3. Site Plan viii 4. Site Plan 26 5. Zoning Map 47 6. Slope Analysis 55 7. Landscape Plan 78 8. Noise Measurement Locations 80 9. Existing Land Use 90 10. Vicinity Street System 97 11. Existing Traffic Volumes 99 12. Project Generated Traffic Volumes 103 13. 1987 Daily Traffic Volume with and without Proposed Project 104 14. Average Annual Accidents 110 15. Childrens Play Area Blow -Up 118 16. Site Utility Plan 124 17. Aerial Photograph 127 18. Cross Section 128 19. View from Tukwila Hill 128 20. Plan View 129 21. Sections of Site 130 -1 Tables 1. Summary of Suspended Particulate Concentrations 63 2. Summary of Automobile Generated Pollutant Levels 64 3. Existing Noise Levels 81 4. EPA Noise Guidelines 81 5. HUD Noise Acceptability Standards 82 6. Interior Evening Noise Levels on Site 83 7. uutdoor Evening Noise Levels on Site 85 8. Traffic Generation Impacts Created by Proposed Project 102 9. Schools Serving Vicinity of Site 113 10. Existing Recreational Facilities 115 11. Park Standards 116 FACT SHEET Name of Proposal Valley View Estates Project Sponsor Puget Western, Inc. One Bellevue Center 411 108th Street NE Bellevue, WA 98004 Nature of Proposal The project involves construction of 108 residential units on a 7.08 acres hillside site. Eighteen three -story buildings, each containing six units, would be stair - stepped into the lower portion of the hillside. Thirty two percent of the site would remain in its natural state. Project Location The site is location in the City of Tukwila in the southwest quadrant of the I -5 /I -405 intersection. It is bordered by 53rd Avenue South and Slade Way on the west, Slade Way on the south, and the Interstate 5 right -of -way on the east. The property is part of an undeveloped, wooded hillside above I -5 overlooking the Green River Valley. See Figure 2, Aerial Photograph. Lead Agency City of Tukwila Planning Department Responsible Official Brad Collins, Planning Director Planning Department City of Tukwila Contact Person Brad Collins, Planning Director City of Tukwila Planning Department City Hall 6200 Southcenter Boulevard Tukwila, WA 98188 (206) 433 -1849 • ..4#10140,111,p014* • !. " • AERIAL PHOTOGRAPH -v11- Ulf Figure 2 ASEK-2CIATE3 • ie . o. •I_,. w z •+ OW••• CTd1r 1.W _ ^ i...G PCi:T1�FJr+7 —MM'S rA{.VRi'iii 111_,w- 4..00 ,. •'r QOM •wVV Y Mk/ 6 NMI 4.144* •Vidb MI aim ORM • - - - - - - - - - - - Authors and Principal Contributors This EIS was prepared under the direction of the City of Tukwila Planning Department. Research and analysis were provided by the following firms: R.W. Thorpe and Associates Planning & Landscape Architecture, Environmental Analysis 815 Seattle Tower 3rd and University Seattle, WA 98101 (206) 624 -6239 Contact: Robert W. Thorpe, AICP; Jon Potter, Project Manager Ann Scales Land Use Consultant 4301 2nd Avenue N.E. Seattle, WA 98105 (206) 634 -0494 Stepan and Associates Engineers 930 South 336th Street, Suite A Federal Way, WA 98003 Contact: Glen McKinney (206) 682 -4771 Mithun and Associates Architects 2000 112th Ave. N.E. Bellevue, WA Contact: Vince Ferrese, A.I.A. (206) 454 -3344 The TRANSPO Group Transportation Planners 23 -148th Ave. S.E. Bellevue, WA 98007 Contact: Kurt Gahnberg (206) 641 -3881 James Van De Vanter Associates, ASLA Landscape Architecture /Site Planning Suite 201, 612 Bellevue Way NE Bellevue, WA 98004 (206)451 -8001 John C. Mauk Environmental Planner P.O. Box 85185 Seattle, WA 98145 -1185 (206) 527 -8953 GeoEngineers Engineers and Geologists 2020 124th NE Bellevue, WA Contact: Jack Tuttle (206) 881 -7900 Towne, Richards & Chaudier Noise Engineers 105 N.E. 56th Seattle, WA Contact: Jan Hauge (206) 523 -3350 Dames and Moore Geotechnical Engineers 155 N.E. 100th Street Seattle, WA 98125 (206) 523 -0560 Puget Western, Inc. Thomas W. Russell, Project Manager P.O. Box 97034 Bellevue, WA 98009 -9734 (206) 454 -6363, ext. 5147 Actions, Permits, and Licenses Required Building Permits Engineering Plan Approvals Site Plan Approval Board of Architectural Review City Utility Permits Electrical Permits Occupancy Permit Utility Hookups All other permits necessary to .construct buildings and improvements proposed on the site. Location of EIS Background Data Tukwila Planning Department City of Tukwila City Hall 6200 Southcenter Boulevard Tukwila, WA 98188 Date of Issue of Draft EIS December 28, 1984 Response Date for Comments on Draft EIS January 27, 1985 Date of Issue of Final EIS January 31, 1986 Cost of Document: $30.00 Any questions on the Final EIS should be addressed to Brad Collins, Planning Director at the above address. DISTRIBUTION LIST Federal Agencies Environmental Evaluation Branch EPA Attn: Ms. Lisa Corbyn, Director 1200 6th Avenue, MS 443 Seattle, WA 98101 Environmental Protection Agency Attn: Mr. Walt Jaspers Director of Federal Affairs 1200 6th Avenue, MS 623 Seattle, WA 98101 Office of Community Planning & Development Attn: Mr. Charles Bickley, Director Department of Housing and Urban Development Arcade Plaza Building, MS 427 Seattle, WA 98101 Department of Energy Attn: Ms. Nan Evans Room 1992, Federal Building 915 Second Avenue Seattle, WA 98104 U.S. Army Corps of Engineers Attn: Col. Leon Moraski Seattle District NPSEN -PL -RP P.U. Box C -3755 Seattle, WA 98124 United States Geological Survey 1201 Pacific Avenue, Suite 600 Tacoma, Wa 98402 State Agencies Environmental Review Section Attn: Ms. Debbie Kneeland Department of Ecology, MSPV -11 Olympia, WA 98504 Washington State Department of Game Habitat Management Division Attn: Mr. Bob Zeigler 600 North Capitol Way Olympia, Wa 98504 Washington State Department of Natural Resources Attn: Mr. Harry Anderson Public Land Building, MS EX -11 Olympia, WA 98504 Washington State Department'of Ecology Attn: Mr. Stan Springer, Head Environmental Review St. Martin's College Campus Lacey, WA 98504 Washington State Dept of Transportation Attn: Mr. Bernie Chaplin Environmental Planner Highway Administration Bldg MS KF -01 Olympia, WA 98504 Washington State Historic Preservation Office Attn: Ms. Jeanne M. Welch, Director 111 W. 21st Ave., MS KL -11 Olympia, WA 98504 Office of Public Archaeology University of Washi ~ ^ + -n Attn: Mr. Jerry Jermann, Director 213 Engineering Annex, FM -12 Seattle, WA 98195 Regional Agencies Mr. R. F. Johnson, P.E. Dept of Transportation District Engineer, District #1 6431 Corson Ave South Seattle, WA 98108 Environmental Planning Division Attn: Rodney G. Proctor, Manager Metro, MS 63 821 Second Avenue Seattle, WA 98104 Metro - Sewerage 1200 Monster Road SW Renton, WA 98055 Metro - Transit 821 Second Seattle, WA 98101 Puget Sound Air Pollution Control Agency Attn: Mr. A. R. Dammkoehler Air Pollution Control Officer P.O. Box 9863 Seattle, WA 98109 Puget Sound Council of Governments 216 First Avenue South Seattle, WA 98104 Seattle /King County Commuter Pool. Program Attn: Mr. William T. Roach, Program Manager Arctic Building, Room 600 704 Third Avenue Seattle, WA 98104 Local Agencies Auburn Planning Department 25 West Main Auburn, WA 98002 Des Moines Planning Department 21630 11th Avenue South Des Moines, WA 98188 Kent Planning Department 220 South 4th Street Kent, WA 98032 Bob Grieve King County Council 4th Floor /King County Courthouse Seattle, WA 98104 King County Dept of Public Works Surface Water Mangement Attn: Mr. George Wannamaker, Director 969 King County Administration Building Seattle, WA 98104 King County Dept of Budget & Program Development EIS Review 400 King County Courthouse Seattle, WA 98104 King County Drainage Dristrict #1 Attn: Mr. Jack Nelson 25403 104th Ave SE #3 Kent, WA 98031 King County Department of Community Development Building and Land Development 410 King County Administration Building Seattle, Wa 98104 King County Dept of Planning & Community Development Planning Division W217 King County Courhouse Seattle, WA 98104 King County Soil and Water Conservation Service 35 S. Grady Way Renton, WA 98055 Renton Planning Department 200 Mill Street Renton, WA 98055 Seattle Water Department 821 2nd Avenue Seattle, WA 98104 Val -Vue Sewer District P.O. Box 68063 Seattle, WA 98168 King County Water - District No. 75 P.U. Box 68100 Seattle, WA 98168 King County Fire District 18 4237 South 144th Seattle, WA 98168 King County Fire District 24 2929 South 200th Seattle, WA 98188 City of Tukwila Mayor /City Administrator City Council (7 copies) Planning Commission (7 copies) Public Works Department Parks and Recreation Department Police Department Fire Department City Attorney Building Division SEPA Information Center Utilities /Services South Central School District #406 4640 South 144th Seattle, WA 98168 Highline School District #401 15675 Amboum Boulevard S.W. Seattle, WA 98166 Puget Sound Power and Light Attn: Mr. Dick Causey Puget Power Building Bellevue, WA 98009 Washington Natural Gas Company 815 Mercer Seattle, WA 98109 Pacific Northwest Bell 107 N. Division Auburn, WA 98002 Newspapers and Libraries Kent News Journal Attn: EIS Review P.O. Box 130 Kent, WA 98031 Highline Times P.O. Box 518 Seattle, WA 98166 Renton Record Chronicle Attn: Real Estate /Urban Affairs 801 Houser. Way South Renton, WA 98055 Seattle Times Fairview & John Seattle, WA 98121 South Seattle Times 6000 Southcenter Blvd., Suite 220 Tukwila, WA 98188 Seattle Post - Intelligencer 6th & Wall Seattle, WA 98121 Daily Journal of Commerce 83 Columbia Seattle, WA 98104 Tukwila Library 14475 59th Street Tukwila, WA 98188 Valley View Library 17850 Military Road South Seattle, WA 98188 Private Organizations and Others Washington Environmental Council 107 South Main Seattle, WA 98104 Tukwila /SeaTac Chamber of Commerce 950 Andover Park East Tukwila, WA 98188 -xv- Green River Study Group Attn: Ms. Carol Stoner P.O. Box 775 Kent, WA 98031 Rainier Audubon Society Conservation Committee Attn: Mr. Keith Bechard P.O. Box 778 Auburn, WA 98002 Neighborhood Residents Mr. Alfred Schmid 1525 Taylor Ave. N. #101 Seattle, WA 98109 Bel Crest Realty, Inc. 12431 Kingsgate Way NE Kirkland, Wa 98033 Mr. Robert C. Christensen 16241 54th Ave S Seattle, WA 98188 Mr. Heinz Ritter 5213 S 164th Seattle, WA 98188 Mr. Jack R. Nyholm 5215 S 164th Seattle, WA 98188 Mr. Patrick Mitchell 16227 54th Ave S Seattle, WA 98188 Mr. Thomas C. Johanson 16231 54th Ave S Seattle, WA 98188 Ms. Ruby A. Mitchell Mr. John D. Mitchell P.O. Box 68015 Seattle, WA 98188 Mr. Gerard A. McElholm 5156 S 160th LSt. Seattle, WA 98188 Mr. Godon M. Solem 5155 S 160th Seattle, WA 98188 M.D. Shawley 15811 53rd S Seattle, WA 98168 J. L. Barnes 15814 51st Ave S Seattle, WA 98188 Mr & Mrs. W. Lester Warehine 12016 26th Ave S Seattle, WA 98188 McNamara Investment Co., Inc. 1600 Dexter Ave N, Suite #1 Seattle, WA 98109 Mr. John Y. Back 4439 S 170th Seattle, WA 98188 Mr. Raymond Nielson 5108 S 163rd P1 Seattle, WA 98188 Mr. Calvin M. Johnson 5110 S 163rd P1 Seattle, WA 98188 Mr. Richard A. Goe 5112 S 163rd P1 Seattle, WA 98188 Mr. Steven Welsh 5113 S 163rd P1 Seattle, WA 98188 Mr. Robert T. Amundson 5111 S 163rd P1 Seattle, WA 98188 Mr. David E. Yankee 5109 S 163rd P1 Seattle, WA 98188 Mr. James F. Rial 16243 52nd Ave S Seattle, WA 98188 Mr. John E. Schwarzmann 16251 52nd Ave S Seattle, WA 98188 R. H. Small 16244 52nd Ave S Seattle, WA 98188 Mr. Herbert W. Phalan 16250 52nd Ave S Seattle, WA 98188 Mr. Edgar D. Bauch 16603 53rd S Seattle, WA 98188 Mr. Robert L. Crain 5105 S 163rd P1 Seattle, WA 98188 Mr. Hans B. West 5212 S 164th Seattle, WA 98188 Mr. & Mrs. Richard McLester 5118 S 164th Tukwila, WA 98188 Mr. & Mrs. Leo Sowinski 16050 51st Ave. S Tukwila, WA 98188 Mr. & Mrs. Dennis Robinson 16038 48th Ave S Seattle, WA 98188 John Barnes 15828 51st Ave S Tukwila, WA 98188 Bernie Onorati 5102 S 163rd P1 Tukwila, WA 98188 Mrs. Ethel Mae Cole 16030 51st Ave S. Tukwila, WA 98188 Al Pieper 17083 53rd Ave S Tukwila, WA 98188 Fred Bigelow 5207 S. 164th Tukwila, WA 98188 Louis Hayes 16634 53rd Avenue South Tukwila, WA 98188 I. SUMMARY A. Summary of the Proposal 1. The Proposed Action The proposal is to construct 108 multi - family residential units on a 7.08 acre hillside site above the west side of Interstate 5 in the City of Tukwila. Eighteen three -story buildings, each containing six units, would be located toward the downslope side of the property. One hundred eighty -two surface parking spaces would be provided on -site for a ratio of 1.7 spaces per unit. An internal roadway would provide access through the site with driveways onto Slade Way at the south end of the site and 53rd Avenue South at the northwest corner of the site. A separate access off Slade Way with a hammerhead turnaround would serve two of the buildings which would be located somewhat higher on the hillside. Approximately 68 percent of the site would be cleared during construction, with considerable cut and fill required to accom- modate buildings, parking areas and roadways. Thirty -two percent of the site would remain in its natural, wooded state. Overall density of the project would be 15.25 dwelling units per acre. 2. Proponent's Objectives for the Proposal The following is a list of the proponent's objectives for the project: o To develop the site in a manner consistent with the City's previous zoning ordinance as provided by the proponent's vested rights and generally consistent with the City's Comprehensive Land Use Policy Plan - excluding the Comprehensive Land Use Plan Map. o To develop a multiple - family development which can be sold for resi- dential use. o To include mitigating measures which are responsive to the environ- mental issues and to the health, safety, and welfare of project residents and neighbors. o To insure environmentally sensitive design that is commensurate with the environmental constraints of the site. B. Summary of Potential Direct and Indirect Environmental Impacts 1. Physical Environment Earth o Potential destabilization of surface soils on slopes during construction if slopes are oversteepened or adequate shoring is not used. o Potential erosion during grading. 1 o Alteration of topography to minimize potential development impacts. o Increased importance of the maintenance of Washington State Department of Transportation's (WSDOT) drainage systems which are a key factor to continued deep- seated slope stability. Water o Potential for temporary adverse effect on surface water quality due to soil erosion during construction period. o Slight increased level of pollutants typical of residential develop- ments in surface and ground water. o Potential for slight elevation of temperature of storm runoff from paved surfaces. o Any use of pesticides, herbicides and fertilizers on landscaping areas may occasionally contribute slight quantities of contaminants to stormwater that would not be removed by the proposed pollution separation devices. o Increased volume of storm water runoff from the site. Changes in potential peak storm water runoff rate may be controlled by a drainage retention and runoff control system; alternately, drainage facilities may be designed for direct discharge into the Green River via existing downstream storm systems. o Increased importance of the maintenance of WSDOT's drainage systems which are a critical factor to continued deep- seated slope stabi- lity. Air o Project traffic would cause slight, long -term increases in automobile - generated pollutants. o Project residents with existing health problems related to asthma, and heart or lung disease might experience aggravation of their con - dition due to the site's location near the I -5 /I -405 intersection and the Southcenter parking lot. o Particulates and construction vehicle emissions would be generated during construction. o Noxious odors would be produced during construction by diesel powered vehicles and asphalt paving. Flora o All natural vegetation from approximately 68% of the site would be removed. Fauna o Removal of vegetation would cause a slight loss in wildlife habitat; most species that currently utilize the site would be displaced and /or eliminated. Noise With windows open, day -night noise levels inside the units would far exceed the standard EPA considers acceptable: i.e., levels would range from 58 -62 Ldn vs. EPA's 45 Ldn standard. With windows open at night, maximum noise levels would far exceed the maximum noise level beyond which a 50% probability of sleep interference occurs: i.e., 67 dBA max vs. threshold of 50 dBA max. • With windows shut, day -night noise levels inside the units would be within EPA's recommended standard, but maximum noise levels in units on the north portion of the site would periodically reach levels at which adverse noise impacts can occur (primarily speech interference and annoyance): i.e., 55 dBA or greater. • Exterior noise levels, including the proposed recreation areas, would have noise levels ranging from levels EPA characterizes as having significant adverse impacts (i.e., Ldn of 65 -70 dBA) to those EPA considers to have unacceptable public health and welfare impacts (i.e., Ldn of over 70 dBA). During the day time, maximum noise levels within these areas would regularly exceed 75 dBA, occa- sionally reaching 85 dBA. • Residential buildings could reduce background noise levels in the children's play area approximately 3 dBA, if located in the south- west corner of the site. Ambient noise levels at this location may still require fencing to achieve noise levels compatible with EPA standards. o Construction noise at the closest adjacent residences could on occa- sion sharply exceed existing traffic noise by up to 12 dBA, although typical construction noise would be masked by noise from the freeway. o Following site grading and before project completion, properties to the west would experience a slight increase in freeway noise (i.e., 2 -3 dBA) due to loss of trees. (Upon project completion, noise attenuation from the buildings would offset this slight increase in noise levels.) Light and Glare o New low -level light sources would be visible at night from buildings and parking areas. Land Use o The proposed action will preclude alternative land uses for the site during the life of the project. o An undeveloped wooded hillside would be converted to a multi - family housing development with associated parking areas and road surfaces. o The proposed three - story, six -unit residential buildings would be substantially larger in scale than surrounding single family homes; the proposed density of 15.25 dwelling units per acre would be 3 -5 times that of the surrounding neighborhood. 0 Although not considered likely, pressure for multi - family rezones in the area could develop over time. o Residents in the surrounding neighborhood would feel a loss in the quality and cohesion of their single family neighborhood. • Project owners would be subject to the conditions of a legal non- conforming use, including restrictions on their abilities to struc- turally alter the buildings in any way which increases its degree of non - conformity. A requirement that proper notification be given to prospective purchasers regarding the project's non - conforming status might be difficult for the City to enforce. • Lending institutions may prefer collateral from the buyer other than the residences for a separate insurance policy to protect their loan. 0 Rates for liability insurance may be higher than average residential rates due to potentially unstable slopes, and the requirements that the City of Tukwila be indemnified from liability for damages arising directly or indirectly from any earth movement on the site. Natural Resources o Building materials and energy would be consumed during construction. Long -term energy use would occur with project occupancy. Population o The City of Tukwila's population would increase by approximately 212 persons. Housing o 108 dwelling units would be added to the City's housing stock, for an increase of four percent. o The percentage of multi - family units in the City would increase from 63 to 67 percent. • The residential units would be substantially larger in scale and density than surrounding single family homes. o The development would be a legal non - conforming use. Owners would be restricted in their abilities to make structural alterations. Transportation and Circulation o Vehicular traffic would increase by approximately 900 daily trips and 90 evening peak hour trips. Affected streets have adequate capacity to accommodate these volumes and affected intersections would not experience a significant decrease in level of service. o A significant proportion of project traffic would have destinations to the west and would travel through adjoining single family neigh- borhoods. o The potential for pedestrian and traffic accidents would increase in proportion to increased traffic volumes. • School children walking to the bus on 51st Avenue South would be required to walk on the shoulder along South 160th Street. o Minimal overflow parking could occur on adjacent streets during large social events within the development. Fire o There would be a slight increase in the demand for fire protection. Police o Response time to police calls could be increased slightly throughout the City. Schools o There would be a slight increase in demand for an additional classroom or portable classroom at Tyee High School. Parks and Recreation o The project would increase demand on local park and recreation faci- lities. (Pedestrian and bicycle access to these facilities is poor.) • Project residents would be exposed to significant adverse noise impacts in on -site recreation areas. o The project would foreclose the possibility of the site's being con- sidered as permanent open space. Maintenance o A slight increase demand of City of Tukwila to maintain roadways in the vicinity of the site. Slight increase in demand of Val Vue Sewer District to maintain sewer lines in the vicinity of the site. o Increased importance of the maintenance of WSDOT's drainage systems which are a critical factor to continued deep- seated slope stabi- lity. o Increased importance of maintenance of all on -site drainage facili- ties both during construction and for the life of the project. o Requirement for long -term monitoring of slope and hydrology instru- mentation by the geotechnical engineering consultant and compliance with associated remedial action plans. Energy o The project would increase the consumption of electricity and petro- leum products during construction and upon project occupancy. Communications /Telephone o The project would require a cable unit capable of carrying 216 lines to the site. Water o The project would increase domestic water consumption by up to 0.04 mgd on a peak day. o Extension of King County Water District No. 75 water lines to the site. Easements along the private road will be granted for access to maintain the system. o Possible brief interruption of water service to the vicinity during connection of the system. o Minimal impact on the City of Seattle 60 -inch water main located on the adjacent property to north due to the proposed development. Sewer o The project would generate sewage flows of up to .05 mgd on a peak. o Sewage generated by the development would contribute to above capa- city conditions at the Renton Metro Sewage Treatment Plant until planned expansion of the plant is completed. o Vehicular travel on South 160th Street /53rd Avenue South could be interrupted temporarily if trenching for water lines is required within the right -of -way. o Relocation of portions of the existing 12 -inch sanitary sewer line so that it will not be under any of the proposed buildings can occur without any disruption of service in the line. Stormwater Please refer to Water Impacts. Solid Waste o The project would generate solid waste and require collection ser- vice. Aesthetics o View of an undeveloped, wooded hillside from the valley floor would be converted to that of a multi - family condominium development with associated parking, roadways, and landscaped areas. o The development would be visible to drivers along Slade Way and 53rd Avenue South. o Views from residences in McMicken Heights would be minimally affec- ted; no view blockage would occur since the existing houses are situated at least 20 feet above the top of the peaks of proposed buildings. Human Health o With windows open, noise levels inside the units would substantially exceed EPA's recommended standard, causing speech interference and annoyance. With windows open at night, maximum noise levels would be far beyond the threshold at which sleep disruption is likely to occur. o Residents using exterior recreation areas would be exposed to con- tinuous noise levels which EPA characterizes as having significant adverse effects. o Short -term annoyance and irritation would be experienced by area residents due to noise and particulate levels generated during construction. o Project residents with existing health problems related to asthma, or heart or lung disease, might experience aggravation of the problem due to the existing ozone concentrations in the area. Archaeology o There is a remote possibility that archaeological or historical resources could be uncovered during construction. 8 Feasibility: The single family development alternative would not meet the proponent's objective of providing a multi - family residential deve- lopment. The necessary site improvements could price the single family homes higher than their market value. 3. Development of a More Intensive Use Description: Under the site's previous R -4 (Low Apartments) and RMH (Multiple Residence High Density) zoning the following uses were poten- tially permitted: R -4 District: Apartment houses, row houses, boarding houses, children's boarding homes, lodging houses, clinic for people only, convalescent homes, nursing homes, convents, private clubs or fra- ternal orders, schools other than those permitted in the R -2 District. RMH District: Any use permitted in the RMH District, Apartment House, hotels; offices and clinics provided they do not exceed the first two stories. Based on the listed permitted uses, a development scenario could have included the following: Use Designation Acres Convalescent Home or Apartment Building and Office (2 story) 2.52 @ 300 SF /Patient lot area, or 2.52 @ 30 DU /AC. Density Yield 350 patients 75 DU's 2.86 @ 40% Site Coverage 50,000 s.f. Impacts: Overall, implementation of this alternative would impact both the physical and human environments to a greater degree than that of the proposed action and thus it would not be a reasonable alternative under SEPA. For example, site disturbance would be substantially increased and traffic generation would be roughly double that of the proposal. Feasibility: This alternative would not meet the proponent's objec- tives nor is it potentially allowed, since a building permit applica- tion pursuant to the site's previous R -4 and RMH zoning was not filed prior to the effective date of the current Zoning Code. 4. Lower Density Multiple Family Development (Variations A ,,and B): Description of Variation A: Under this lower density alternative, five fewer buildings would be constructed providing a total of 13 buildings and 78 dwelling units. Impacts of Variation A: For the most part, adverse environmental impacts would be proportionately less than those created by the pro- posed action. Site coverage, including the size of the parking lot 9 would be reduced and an additional .5+ acre of undeveloped open space would be preserved. Population on the site would be reduced by approximately 28 %, with the demand on public facilities and services reduced accordingly. Traffic volumes likewise would be reduced by approximately 28 %. Feasibility of Variation A: Construction of five fewer multi - family buildings would meet the proponent's stated objectives for multi - family development but not at the density permitted under vested zoning. This alternative might not be economically feasible due to the higher site improvement costs and infrastructure costs per dwelling unit compared to the proposed action. Housing costs would be higher and conceivably, more than their market value. Description of Variation B: Under this lower density alternative, two fewer buildings would be constructed. Specifically, Buildings No. 1 and No. 2 which are proposed for the southwest portion of the site on slopes of 30 -40% would be eliminated. Impacts of Variation B: The buildings in question are located in a steep, uphill area (30 -40% slopes) near the location of the landslide which occurred on the property in 1960 -61 as a result of a borrow pit excavation. Elimination of these two buildings would eliminate any potential risks associated with construction in an area of questionable slopes. Otherwise, impacts of this alternative generally would be reduced in proportion to the reduction in density, i.e., two fewer buildings and 12 fewer units. The entire southwest corner of the site would be preserved as open space and the second driveway onto Slade Way would not be required. Feasibility of Variation B: Reduction of the project size from 18 to 16 buildings and 108 to 96 units would achieve the proponent's stated objectives for multi- family development but not at the density per- mitted under vested zoning. While this alternative would result in less economic return to the developer than the proposed action, SEPA does not provide that a "reasonable" alternative must provide a desired economic result. Potential loss of income from these units might be partially offset by avoiding the higher site improvement and infrastructure costs that could be associated with developing this por- tion of the site. 5. Revised Building Design Description: The building design could be revised to mitigate noise impacts on project residents. Specifically, the bedrooms could be located on the west side of the buildings, east - facing decks could be enclosed with glass, and a forced -air ventilation system provided. Impacts: Evening noise impacts on project residents would be reduced with the added distance in walls between the bedrooms and noise generated from I -5. Forced -air ventilation would eliminate the need to open windows, which would significantly reduce noise within the dwelling units. (Under the proposed action, with windows open, day- 10 night noise levels and nighttime maximum noise levels far exceed recom- mended standards.) Glass enclosure of east - facing decks would reduce interior noise and increase the utilization of the decks. The cost per unit for these features would be slightly higher than the cost of the proposed building design which might eliminate some potential buyers who otherwise could afford to reside in the proposed project. All other impacts described in the EIS would remain the same. Feasibility: This alternative meets the proponent's stated objectives. While relocation of the bedrooms and a forced -air ventilation system are design elements that probably would need to be incorporated at an early stage, glass enclosure of the decks could be an option available to prospective buyers. The cost of this option could then be added to the price of the unit. D. Summary of Mitigating Measures Note: When the Final EIS states that mitigating measures "will" or "shall" be undertaken, such measures are already planned as part of the proposal or have been committed to by the project sponsor. The word "may ", "could ", or similar language is used to indicate that the City in its discretion, and in conformance with SEPA, will consider these addi- tional mitigating measures as possible conditions of building permit issuance. In some cases, where numerous mitigation measures are discussed (e.g., Noise Mitigation), they have been grouped to distinguish those currently proposed by the applicant from those the 'City will consider as possible additional conditions of permit issuance. Earth All recommendations contained within the geotechnical report (Appendix A) will be complied with by the project sponsor. Mitigating measures and recommendations include, but are not limited to, those summarized below: ° Normal monitoring and maintenance of the existing deep drainage facili- ties on the I -5 right -of -way shall be performed by the Washington State Department of Transportation (WSDOT). The Department of Transportation is also responsible for replacement of drainage systems that are ino- perative or worn out within their right -of -way. WSDOT has not been maintaining the vertical wells per se, but they are flushing the hori- zontal drains that tap into the vertical wells. Based on existing data, it appears that the majority of the vertical wells and /or hori- zontal drains are blocked to some degree. The existing drainage systems are considered critical to maintaining deep- seated slope stabi- lity above the adjacent roadways. The existing WSDOT drainage system is assessed by the geotechnical consultants as still effective in main- taining water levels low enough for adequate deep- seated slope stabi- lity on the project site. ° As a condition of grading and building permit issuance, the City of Tukwila could require that formal agreements be reached between the developer and the State of Washington regarding long -term commitments for adequate monitoring, maintenance and implementation of any remedial 11 measures necessary to maintain the stability of both the project site and the WSDOT right -of -way. These detailed agreements will list each parties' responsibility for monitoring and maintenance of the various facilities and shall include contingency plans for implementation of any required remedial measures. o Slope movement and ground -water levels shall be monitored by means of an instrumentation program which will be maintained throughout the construction phase and during the entire life of the project. A detailed action plan shall be prepared and promptly implemented in the event of significant changes in water levels or indications of slope movement. The geotechnical consultants shall be retained to provide or direct long -term monitoring and data interpretation, evaluate the per- formance of the hillside and recommend what, if any, remedial measures may be appropriate. As a condition of building permit issuance, the developer and project owners may be required by the City to post three bonds. One bond could make funds available to restore the existing environment and sta- bility of the hillside in the event that, during construction, the pro- ject is determined by the developer to be unfeasible for any reason. The second bond could make funds available to adjacent property owners to compensate for damages caused directly from any earth movement on the site at any time during the life of the proposed development. The third bond could make funds available, as required, to ensure that the geotechnical consultant is retained to provide or direct the slope instrumentation /monitoring program during the life of the project and for implementation of any remedial measures required to maintain the stability of the project area. o The contractor shall comply with the geotechnical engineer's general sequence for site development. Site grading shall be undertaken during the late summer - early fall months when the least amounts of rainfall can be expected and surface runoff and seepage from springs should be somewhat diminished. o Individual structure grading shall be performed on an alternating basis, with the number of sites prepared limited to the number for which foundation, retaining wall construction and backfilling can be completed during the dry season. Construction shall be scheduled so that site grading, drainage installation, and surface stabilization are completed in any given area within a single construction season. o All permanent cuts steeper than 3:1 horizontal to vertical (33 percent) shall be supported by retaining structures constructed and backfilled per specifications of the geotechnical report. o Except for localized areas near the existing gully, general fill placed on the site shall not extend above the original ground surface. Temporary stockpiles, if any, shall be placed at the north end of the site and shall be limited to minimize potential impacts on slope stabi- lity and erosion. 12 o The existing 12 -inch sewer line will be realigned so as not to be located below any building structures. o Building foundations, retaining walls, and associated drains shall be constructed per specifications of the geotechnical report. o See related Mitigating Measures listed under "Geology and Soils ", and "Ground Water Movement, Quantity, Quality," in Chapter III. o City of Tukwila requirements for grading and excavation will be followed to minimize or avoid erosion. o Plastic sheets and mulch will be used on portions of the exposed soil areas during construction to minimize erosion. o Landscaping shall be installed as soon as possible subsequent to completion of construction and shall include plants suitable for the stabilization of the surface of steep slopes. o Collection of seepage and springs will be done prior to and during construction to minimize surface flow that could cause erosion. Onsite horizontal drains will be located and connected to the site drainage facilities. o See related Mitigating Measures listed under "Erosion ", and "Surface Water Movement, Quantity, Quality, Runoff /Absorption ", in Chapter III. Air o Measures to control dust during construction, such as watering exposed areas and cleaning and sweeping of streets at the end of hauling acti- vities, will be performed by the contractor as necessary. o Low - emission construction equipment could be used whenever feasible. o Unnecessary motor vehicle engine idling during construction could be prevented by shutting off engines when not in use. Water o A stormwater system designed in accordance with City of Tukwila requirements and the recommendations and requirements detailed in the geotechnical report is proposed to be installed. The City of Tukwila must approve stormwater drainage plans prior to issuance of the building permit. o Changes in potential peak storm water runoff rate may be controlled by a drainage retention and runoff control system; as an alternative, drainage facilities may be designed for direct discharge into the storm drainage system for conveyance and discharge into the Green River. o If a stormwater detention system is selected, it will be designed for a 10 -year storm and be capable of detaining 2,480 cubic feet of water. 13 Detention for a 10 -year storm is normally required by the City of Tukwila. Stormwater would be stored in underground storage pipes. The detention system would also have an emergency overflow. The proposed stormwater collection and detention system would reduce the potential for adverse off -site impacts from runoff by controlling the rate of release to that which occurs under existing conditions. The length of time over which peak discharge would occur would be prolonged. o If direct discharge of stormwater is incorporated into the drainage plans (no on -site detention), stormwater would flow to the Green River through a series of downslope pipes and open channels. This would eli- minate the potential for leakage from the detention structures and reduce the level of excavation and disturbance of the hillside. Upgrading of offsite drainage facilities would be provided where required to prevent adverse effects on these facilities. o All required temporary sedimentation and control facilities will be constructed and in operation prior to earthwork, building construction, and paving. o Catch basins and oil /water separators are proposed within the on -site drainage collection system to separate sediments and petroleum residues from stormwater. On -site detention and the outlet control structure would further allow for separation of these pollutants from stormwater before release from the site. o Prior to site clearing, an interceptor trench will be installed at the toe of the roadway fill along the western boundary of the site as recommended in the geotechnical report and as shown on the site utility plan. o Temporary drainage ditches will be installed to collect runoff imme- diately following site clearing and grubbing. o A portion of the existing perforated storm system (D -3 drain) will be abandoned and replaced by the contractor /developer with a new storm line to handle off -site runoff as shown on the site utility plan. The existing storm line that is above ground and leaking will be repaired. The Washington State Department of Transportation will review and approve plans for such improvements. o Existing on -site horizontal drains shall be located and flows shall be collected and directed into the site drainage control systems. o Site drainage systems will be designed to eliminate or minimize the opportunity for ground water recharge, including lining surface drains to prevent infiltration and constructing subsurface drains to minimize the potential for leakage or breaks. o Permanent French drains will be installed along the upslope sides of all parking areas, in the west trenching gully that crosses the site, and in any wet areas along the west side of the building units. 14 o Foundation and retaining wall drains will be installed and connected to drainage systems along the east property line so the flow can be pro- perly disposed of off the site. o Temporary stormwater management and erosion control measures will be utilized during construction. Where possible, natural vegetation for silt control shall be maintained. Proposed interim drainage and ero- sion control measures include placing straw bales in drainage ditches and swales, directing runoff toward temporary siltation ponds, seeding and placing jute matting. o All temporary siltation ponds and other drainage and erosion control measures shall be maintained in a satisfactory condition until such time as cleaning and /or construction is completed and permanent drainage facilities are operational. o The contractor /developer will have maintenance responsibility for the drainage control facilities during construction. The property owner(s) should be required to assume long -term maintenance responsibility for these facilities after completion of the development. Catch basins and oil /water separators should be cleaned frequently and properly main- tained to assure maximum attainable pollution separation. o Cleaning of streets and parking areas shall be undertaken whenever necessary during construction by the contractor /developer. o See related Mitigating Measures listed under "Geology and Soils," regarding cleaning, flushing and regular maintenance of existing WSDOT drainage facilities. o See related Mitigating Measures listed under "Surface Water Movement, Quantity, Quality, Runoff /Absorption," in Section III, regarding sur- face drainage and stormwater detention facilities. Flora o Approximately 2.3 acres, or 32% of the site, will remain in its natural state, including the southwestern portion of the site. Disturbed areas not proposed for landscaping will be treated for erosion control by seeding with clover and rye or ivy. o Ornamental vegetation will include sycamores along Slade Way and along the perimeter of the parking lot. Vine maple and flowering cherry will be interspersed among the buildings. Additional plant materials will include platinia, rhododendron, mahonia, vibrunum Davidi, ivy and lawn. The proposed landscape plan will be subject to approval by the Board of Architectural Review. 15 Fauna o Approximately 2.3 acres or 32% of the site will remain in its natural state. Noise Proposed Mitigating Measures (i.e., currently committed by the pro -ject sponsor): o The use of glass windows and doors with an acoustical performance at least 5dBA better than conventional thermal insulated windows will be used on the north, south and east facing sides of the buildings to attain an exterior -to- interior noise reduction of 30 dBA throughout the project (5dBA better than conventional construction). The windows will have a minimum overall outside thickness of one inch and will be set in resilient gaskets. Operable windows and exterior doors (including glass doors) will be hinged rather than sliding, and will have resi- lient seals. In addition, exterior doors will have automatic threshold drops or compressible neoprene threshold seals. Detailed specifica- tions for these windows and doors are described in Appendix B. This mitigation measure will bring interior noise levels to an Ldn of 38 on the south part of the site and 42 on the north part of the site, which is generally acceptable interior Ldn based on EPA's Guidelines. Maximum noise levels at night would be reduced to 47 dBA at both loca- tions, which is less than the 50 dBA nighttime maximum threshold beyond which the probability of sleep interference is over 50 %. o Proposed construction materials will generally include double wall construction and one -half inch gypsum wallboards, R -11 fiberglass bat insulation and double glazed aluminum windows. These materials will help attain the noise reductions referenced above but will not provide additional attenuation beyond the proposed 30 dBA reduction. o The location of the proposed children's play area in the southwest corner of the property will reduce noise levels at that location by about 3 dBA. Fencing would still be needed to reduce noise levels to an Ldn of 55 dBA or less which is the minimum level for avoiding speech interference and annoyance outdoors. o Construction will not occur before 7:00 a.m. on weekdays and 9:00 a.m. on weekends, or after 10:00 p.m., to prevent state noise code viola- tions. In addition, any diesel or gasoline power equipment used at the site will be required to have a proper muffler that is in good con- dition. Potential Mitigating Measures (not currently proposed by the applicant; possible conditions of building permit issuance): o Forced -air ventilation could be required, especially in bedrooms, so that windows could be kept closed and noise levels maintained at accep- table levels. (With windows open, interior noise levels are 10 -15 dBA higher than when windows are closed.) 16 o Additional exterior spaces, such as the proposed recreation areas, could be enclosed by noise barriers to reduce exterior Ldn below the level where EPA indicates that significant adverse noise impacts occur. The acoustic barriers could be constructed of wood with a minimum thickness of 3/4 inch. Plywood, or board and batten construction would be acoustically acceptable. Such barriers would have no gaps or ope- nings, including the base. These barriers would have the disadvantage of blocking views from the site. • Noise levels on the outdoor decks could be reduced by about 5 dBA by using a solid barrier around the deck of the material described above. The barrier would need to be high enough to block views from the freeway from a typical user location (presumably seated), but would not need to be so high that it blocked views of the valley and mountains to the east. o East - facing decks could be glass enclosed, to effectively provide double windows between the outside and inside of the residential units. If this construction were used, the one -inch window thickness proposed for exterior windows would not be necessary for the exterior or interior windows of the deck area. Light and Glare o Parking lot lighting will be directed so that no direct light spills off site. o Exterior light fixtures will be selected which do not project light above 20 feet in height. o Perimeter landscaping will reduce light spillage. Land Use o The buildings will be sited along the east half of the property which provides a 50 to 30 foot topographic separation from 53rd Avenue South. (Existing houses west of the site are a minimum of 20 feet above the roof peaks'of proposed buildings.) o The site plan provides a landscaped buffer along the western edge of the property partially screening the housing from commuters on Slade Way and 53rd Avenue South and from residences in the McMicken Heights vicinity. Housing o (See Land Use Mitigation) Transportation /Circulation o A left -turn lane for westbound -to- southbound left -turns from Klickitat Drive to 53rd Avenue South will be provided to eliminate conflicts bet- ween left - turning traffic and westbound through traffic. 17 o . Roadway shoulders on S. 160th Street between the project site and 51st Avenue South could be widened to a minimum of four feet to facilitate safe pedestrian access (particularly for school children) to 51st Avenue South. o Project driveway locations will be located at least 150 feet away from the nearest intersection as per the proposed site plan. ° The developer will work with Metro Transit to ensure a safe, convenient bus stop location for project transit patrons adjacent to the site. o By City Ordinance, sidewalks will be required along the perimeter of the project site adjacent to public roadways, i.e., along Slade Way and 53rd Avenue South adjacent to the development. o A gravel path or sidewalk could be provided along the east edge of the on -site circulation aisle with a crosswalk installed at the north entrance to the primary parking area to ensure that school children and other pedestrians can walk through the site separated from project traffic. o Speed bumps could be installed within the on -site circulation aisle (no closer than every 200 feet) to control traffic speeds on- site. o The project driveway onto 53rd Avenue South could be designed to include a level platform extending 30 feet beyond the driveway stop line to enhance visibility of oncoming traffic for drivers exiting the project. o Parking spaces in excess of City requirements will be provided on site for 20 vehicles to accommodate frequent parking demand conditions in excess of 1.5 spaces per dwelling unit. o Assignment of parking spaces to specific residential units could be prohibited so as to assure the flexibility needed to accommodate fluc- tuating demands in the primary parking areas. o Parking of recreational vehicles or trailers on site could be prohi- bited to ensure that residential and visitor parking flexibility is maintained. This restriction could be assured through condominium covenants. Fire Service o Une approved fire extinguisher will be provided in each unit and smoke detectors will be installed per the Uniform Building Code Section 1210. o A 20 -foot wide unobstructed driving lane with a 35 -foot turning radius will be required through the site. o Protective curbs or guard posts for all sprinkler valves, hydrants, gas meters and transformers will be provided. 18 o Certain driving and parking areas could be declared "fire lane - no parking" areas per Ordinance 1110. Police Service O A close working relationship between the developers and the Police Department's crime prevention officer will be maintained throughout the planning and building phases of this project to minimize crime and per- sonal safety risks potentially associated with the project. Adequate parking on -site will minimize problems associated with off - street parking, such as vehicle and pedestrian accidents, auto thefts and car prowl incidents. Parks and Recreation o A 6,175 square foot children's play area will be provided including an open play area, sand box, and other play equipment. O A minimum of 200 square feet of recreation area per dwelling unit will be provided, in addition to all other requirements of Section 18.60.200 of the Zoning Code, "Recreation Space in Multi- family Districts." Maintenance o Formal agreements could be required between the developer and the State of Washington regarding long -term commitments for monitoring, main- tenance and repair of the WSDOT drainage systems and all storm water and drainage facilities that could potentially adversely affect the stability of the project area for the life of the project. o The geotechnical engineer shall be retained to provide or direct long- term monitoring and maintenance of instrumentation installed to eva- luate the stability of the project site for the life of the project. o The developer and the property owner(s) could be responsible for main- tenance of all onsite drainage and erosion control facilities. o Runoff at the north side of the site will be controlled so as not to adversely affect the City of Seattle's 60 -inch water line. o The contractor will ensure that trucks carrying excavation loads are covered with canvas or tarps if necessary for dust control. O The developer will provide street and ditch cleaning during construc- tion as necessary. Energy o Double - glazed aluminum windows and R -11 fiberglass insulation will be utilized (see Noise mitigating measures). Insulated walls, floors, roof and glass could be used throughout all structures. 19 o An energy analysis of building design elements could be undertaken to assess the feasibility of reducing long -term demand, e.g., passive solar energy systems. Communications /Telephone • All telephone lines will be installed underground. o Installation of telephone lines will be coordinated with installation of electrical lines. Water Service o Installation of water restrictive fixtures and devices such as flow restrictors in new dwelling units could reduce water consumption, if such measures are determined necessary or desirable. Sewer o The existing 12 -inch sewer line on the site will be relocated to avoid having buildings constructed atop it. Relocation of the line would significantly improve access for future maintenance and would minimize the likelihood of a break in the line going undetected or unrepaired for a period of time, thereby contributing to a potential soils loading problem. o If water use were reduced by residents implementing water - saving measures in their homes, the volume of sewage that would be discharged from the project would be reduced. Stormwater o (See Water Section) Aesthetics o Existing vegetation will be maintained to the extent possible along the eastern portion of the site. 0 Ornamental vegetation will include sycamores along Slade Way and along the perimeter of the parking lot. Vine maple and flowering cherry would be interspersed among the buildings. Other plant materials would include platinia, rhododendron, mahonia, vibrunum Davidi, ivy and lawn. o The Landscape Plan, which is subject to approval of the Board of Architectural Review, could include plant materials similar in character to existing vegetation on the site. Human Health o Please refer to the mitigating measures listed under Noise and Air above. 20 E. UNAVOIDABLE ADVERSE IMPACTS Physical Environment Earth o While the recommendation for earthwork, site drainage and erosion control structures for the project are intended to increase surficial slope stability, there is always the possibility that localized con- ditions may vary to the extent that some earth movements might occur during construction, particularly where zones of seepage are encoun- tered. These are anticipated to be small in nature and are not expected to result in any earth spillage outside of the site limits. o Site alterations during portions of the construction phase may result in temporary slopes somewhat steeper than the final configuration that will be achieved. o Stripping of site vegetation will create the possibility of surface erosion due to rainfall and seepage from springs; any potential offsite impacts will be controlled by implementation of a City- approved tem- porary erosion and sedimentation control system. Air o Project traffic would slightly increase automobile- generated pollutants in the vicinity. o Project residents with existing health problems related to asthma, and heart or lung disease might experience aggravation of their condition due to the site's location near the I -5 /I -405 intersection and the Southcenter parking lot. o Construction activities would cause a short -term increase in par- ticulate levels. o Short -term noxious odors would be produced during construction. Flora /Fauna o All natural vegetation from approximately 68% of the site would be removed. o Removal of vegetation would result in some loss of animal habitat and the displacement and /or elimination of most species that currently uti- lize the site. Noise o With windows open, day -night noise levels inside the units would far exceed the standards EPA considers acceptable: i.e., levels would range from 58 -62 Ldn vs. EPA's 45 Ldn standard. With windows open at 21 night, maximum noise levels would far exceed the maximum noise level beyond which a 50% probability of sleep interference occurs: i.e., 67 dBA max. vs. threshold of 50 dBA max. o With windows shut, day -night noise levels inside the units would be within EPA's recommended standard, but maximum noise levels in units on the north portion of the site would periodically reach levels at which adverse noise impacts can occur (primarily speech interference and annoyance): i.e., 55 dBA or greater. o Without acoustic fencing, exterior noise levels, including the proposed recreation areas, would have noise levels ranging from levels EPA characterizes as having significant adverse impacts (i.e., Ldn of 65 -70 dBA) to those EPA considers to have unacceptable public health and welfare impacts (i.e., Ldn of over 70 dBA). During the daytime, maxi- mum noise levels within these areas would regularly exceed 75 dBA, occasionally reaching 85 dBA. • Construction noise at the closest adjacent residences could on occasion sharply exceed existing traffic noise by up to 12 dBA, although typical construction noise would be masked by noise from the freeway. o Following site grading and before project completion, properties to the west would experience a slight increase in freeway noise (i.e., 2 -3 dBA) due to the loss of trees. (Upon project completion, noise atte- nuation from the buildings would offset this slight increase in noise levels.) Land Use o An undeveloped, wooded hillside would be converted to a multi - family housing development with associated parking areas and road surfaces. o The project's character, including density and scale, would differ substantially from that of the surrounding single family neighborhood. o Residents in the surrounding area would feel a loss in the quality and cohesion of their single family neighborhood. o Property owners would be subject to the conditions of a legal non- conforming use, including restrictions on their abilities to make structural alterations to the buildings. A requirement that proper notification be given to prospective purchasers regarding the project's non - conforming status might be difficult for the City of enforce. o Project owners will be subject to the conditions and requirements of the building permit regarding retaining the geotechnical engineering consultant to provide or direct the slope instrumentation and moni- toring program during the entire life of the project. o Project owners might be required to pay for additional insurance or provide collateral other than the condominiums to protect loan institu- tions in case of fire or other losses. 22 Natural Resources o Building materials and energy would be consumed during construction. Human Environment Transportation /Circulation o The project would generate increased traffic through residential neigh- borhoods west of the site. o The potential for traffic and pedestrian accidents would increase in proportion to increased traffic volumes. o School children walking to the bus on 51st Avenue South would be required to walk on the shoulder along South 160th Street. o Approximately 25 percent increase in the left -turn component from Klickitat Drive to 53rd Avenue South. o Short -term impacts on vehicular travel at South 160th Street /53rd Avenue. South if trenching is required within the right -of -way or across the road. o Minimal overflow parking could potentially occur on 53rd Avenue South, Klickitat Drive or Slade Way during large social events. Public Services o The project would increase the demand for fire protection. ° Response times to police calls could increase slightly throughout the City. o The project would slightly increase demand for an additional high school classroom. o The project would increase demand on local park and recreation facili- ties. (Pedestrian and bicycle access to nearby facilities is poor.) o The project would foreclose the possibility of the site's being con- sidered as permanent open space. o The project would increase the demand for long -term City maintenance. Public Utilities o Unless that portion of the sewer line located beneath four of the pro- posed buildings is relocated, a sewer line break could go undetected or unrepaired for a period of time, causing potential soils loading and in turn, possibly contributing to slope instability. o Energy demand on the site would increase over both the short- and long- term. 23 o Sewage generated by the development would contribute to above capacity conditions at the Renton Metro Sewage Treatment Plant until planned expansion of the plant is completed. Aesthetics o The view from the valley floor of a steep wooded hillside would be replaced with that of a multi - family residential development. Human Health o Short -term annoyance and irritation would be experienced periodically by area residents during construction due to high noise levels and generation of particulates. o With building windows open, residents could experience high levels of speech interference and annoyance and serious sleep disruption at night. o Project residents using outdoor recreation areas could be exposed to significant stress due to continuous noise at high decibel levels. o Project residents with existing health problems related to asthma, and heart or lung disease might experience aggravation of their condition due to the site's location near the I -5 /I -405 intersection and the Southcenter parking lot. Economic o City costs would increase to provide needed services for the residen- tial project. 24 mum 1••••••• 1.001 333•63. • -R..o n•■ y TOW ..rli. pb I ...• •••• •30.9•1- .LL.11t 133~ • , .,PW..rcr�3a, �•' S HR4l..!YO�'K7. 4# ••■■ S. 4 ■•• +..r • s- %. One hundred sixty -two surface parking stalls would be provided on the west or uphill side of the buildings. An additional 20 stalls for overflow parking would be provided further to the west, below 53rd Avenue South, for a total parking ratio of 1.7 stalls per unit. An internal roadway would provide access through the site with driveways onto Slade Way at the south end of the site and 53rd Avenue South near the northwest corner of the site. A separate dead -end access off Slade Way would serve the two buildings located higher on the hillside. Approximately 68 percent of the site would be cleared during construction. Considerable excavation and limited filling would be required to provide suitable locations for the buildings, which would be stair-stepped into the hillside, and to accommodate parking and roadways. It is anticipated that retaining walls would be required for all structures. In addition, retention of cut slopes and fill embankments would be required along por- tions of the parking area and near the two upper buildings. Substantial drainage improvements would be required, in light of existing runoff from the site, numerous seeps and springs onsite, and evidence of past slope instability. These improvements would include repair and /or replacement of existing storm drainage facilities, installation of inter- ceptor ditches along the west side of the site, French drains around the west side of parking and building areas, a footing drain system around the buildings and retaining walls, and appropriate stormwater control systems. Approximately 32 percent of the site would remain in its natural state, including the upper hillside along the west side of the property. Areas which would remain in its undisturbed state amounts to approximately 2.3 acres. Following building construction, landscaping of disturbed areas would include plantings of sycamores along Slade Way and the perimeter of the parking lot, and vine maples and flowering cherry interspersed among the buildings. Building exteriors would be stained wood siding and stucco with cedar trim and composition shingles. Planting would include sycamore along Slade Way and the parking lot. Vine maple and flowering cherry would be interspersed among the buildings. Other plant materials would include platinia, rhododendron, mahonia, viburnum Davidi, ivy and lawn. H. Relationship to Existing Laws, Policies, and Plans 1. City of Tukwila Comprehensive Policy Plan, 1977 The City of Tukwila Comprehensive Land Use Plan serves as a basic source of reference for future legislative and administrative land use actions within the City. The Plan is intended to provide direction for the orderly and coordinated development of the City, but is not a regu- lation of property rights or land uses (RCW 35A.63.080). The Tukwila Comprehensive Land Use Plan Map designates the site for Low Density Residential development, up to five dwelling units per acre.' A portion of the site also is shown as having special development considerations, due primarily to steep slopes, soil conditions and nearby springs. The Environmental Base Map, which is general in nature, indicates that the 27 site contains both natural amenities (i.e., woodlands) and environmen- tal constraints (i.e., steep slopes, and unstable slopes). Please refer to the following section on "Earth" and Appendix A - Geotechnical and Hydrological Studies, for a detailed analysis of slope stability. Comment: The proposed density of 15.25 dwelling units per acre is three times the maximum potential density recommended for this area by the Comprehensive Plan Map. However, the proposed density is con- sistent with the zoning in effect at the time the building permit application was filed with the City. (See following Zoning Code Discussion.) The following is an analysis of objectives and policies of the Tukwila Comprehensive Plan, which has been revised and expanded based on com- ments on the Draft EIS. City Comprehensive Plan policies are the prin- cipal instrument through which the City's substantive authority under SEPA is implemented. GENERAL GOALS 1. Natural Environment "GOAL 1. Gauge Development of the Land in a Manner Suitable to the Natural Environment ". Comment: The site is identified as having special development con- siderations on the Comprehensive Land Use Map. "The Data Inventory: Tukwila Planning Area" shows the site in or partially in areas defined as unknown slope stability; rolling and steep slopes, springs and major wooded area. The results of the geotechnical study indicate that, with proper design and construction monitoring, the property can be developed in the manner proposed without endangering the stability of the site with respect to either deep- seated or shallow slope movements. These two mechanisms of slope failure are assessed to be basically independent of each other at this site. The existing subsurface drainage facilities installed by the State of Washington are a critical element for protection of the adjacent highway system, and satisfactory performance of the WSDOT drain systems is the primary mechanism for control of deep- seated movements. Adequate maintenance of this system is necessary both from the standpoint of public interest and safety with respect to use of the highway and street systems, as well as for the continued long -term stability of the project site. Surficial slope movements are largely affected by surface runoff, near surface infiltration of rainfall or runoff, and oversteepening or overloading in the thin mantle of less competent soils that overlies the area. Control of surficial slope movements will be achieved by the installation of various interceptor trench and French drain systems at appropriate locations on the site, temporary drainage systems and per- manent storm drain lines, footing and retaining wall drain systems around the proposed buildings, limiting the size and location of temporary stock- piles, sequencing building construction, controlling cut slope angles or 28 providing shoring /bracing of excavations, and provisions for construction monitoring and instrumentation by the geotechnical engineer. Overall load changes on the property will be relatively small for the type of building construction and final grades planned. The net increase in load within the strip of property which will be occupied by the struc- tures, including adjacent yard areas, will be on the order of 300 pounds per square foot taking into account design building loads and cutting and filling activities. Foundations will, for the most part, be supported on the more competent soils represented by Unit B (see geotechnical engi- neering report, Appendix A). "GOAL 2. Use and Preserve the Natural Features and Resources of the Physical Environment in a Wise and Posterity- Oriented Manner." Comment: Development as proposed would preserve approximately 32 percent of the site in its natural state, with 68 percent of the site permanently .altered for residential use and parking. The project forecloses the possibility of maintaining this portion of the wooded valley wall above I -5 as open space. Whether the proposal represents a wise use of the pro- perty depends in part on assurances that the stability of the hillside can be maintained over the long term. "GOAL 3. Protect and Enhance the Natural Amenities and Aesthetic Resources of the Tukwila Area for the Public's Welfare." Comment: The site is located in an area which has been designated in the "Data Inventory" as a major wooded area. Development as proposed would eliminate approximately 4.8 acres or 68% of the woodlands on the site. Approximately 2.3 acres or 32% of the site would remain in its natural state. 2. Open Space "GOAL 1. Create an Integrated Network of Open. Space Based on Existing and Proposed Recreational Areas, Lands Least Suitable for other Development, and the Natural Amenities of the Tukwila Area." Comment: The project would convert part of an undeveloped, wooded hillside that presently serves as a visual buffer between the I -5 corridor and uphill residential properties to a multi - family development. However, the City's Comprehensive Plan does not designate the site as a greenbelt or future park area. Planned park improvements in the vicinity include development of the 11 -acre Crestview Park across located 53rd Avenue South northwest of the site, although pedestrian and bicycle access to this site and other nearby recreational facilities is poor. The proposed develop- ment includes a 6,175 square foot children's play area on the site, as well as 200 square feet of recreational area for each dwelling unit. "GOAL 2. Provide Vivid, Diverse Open Space. Experiences which Fit Easily Into the Pattern of Daily Life." Comment: Approximately 32 percent of the 7.08 acre site will remain in its natural state. A 6,175 square foot play area for children is proposed 29 as well as 200 square feet of recreational area per dwelling unit. Steep slopes may render portions of proposed recreational areas unusable for recreational purposes, however, and may fail to qualify as such under City regulations. The adequacy of designated recreational areas will be deter- mined upon review of grading plans for the site. Exterior noise levels could expose residents to significant adverse effects due to the site's proximity to I -5. "GOAL 3. Provide Meaningful Recreational Opportunity for All People of Tukwila Regardless of Sex, Age, Color, or Socio- economic Status." Comment: Since the proposed project is a private development, the recreational area will be provided for project residents only. The same ,facilities will be available to all project residents. 3. Residence "GOAL 1. Preserve the Pleasantness and Integrity of Viable Single Family Areas." Comment: The density, scale and population of the proposed development and projected traffic volumes, would be substantially greater than those of the surrounding single family homes. As reflected by comments on the Draft EIS (see Part Two, Comments and Responses) many nearby residents believe the project will seriously diminish the pleasantness and integrity of their neighborhood. The relative topographic isolation of the site from uphill properties, proposed open space, landscape buffers, and miti- gating measures described in this EIS will minimize some of the project's impacts on the existing residential neighborhood. "GOAL 2. While Protecting the Single - Family Areas of Tukwila, provide Adequate Room for Multiple - Dwellings." Comment: Other areas of the City have been designated by the Comprehensive Plan as appropriate for Multi- family development. The pro- posed multi - family development at the subject location will be a legal nonconforming use in a single family neighborhood. Given the single family zoning and low density comprehensive plan designation of nearby properties, this proposal is not expected to be a precedent for additional multi - family development. However, as pointed out in several comment let- ters on the Draft EIS, there is no guarantee that over time, pressure for multi - family rezones would not arise. "GOAL 3. Assure an Adequate and Diversified Housing Supply Within the Residential Community." Comment: The proposed development would increase multiple family develop- ment in Tukwila from 63 to 67 percent of all dwelling units. 5. Transportation /Utilities "GOAL 1. Provide an Adequate Transportation System Capable of Moving People and Goods in a Manner consistent with Compatible Land Use Patterns." 30 31 Comment: The wooded character of this portion of the valley wall will be permanently altered. All areas not built upon or left in their natural state will be landscaped, with the steeper slopes generally covered with ivy and loam. Approximately 32% of the existing natural vegetation will be retained. "Policy 2. Encourage the Use of Live Vegetation in Conjunction With the Actual Development of the Property." Comment: Proposed landscaping consists solely of natural plant materials. "Policy 3. Discourage Disturbance of Vegetation When Not in Conjunction With the Actual Development of the Property." Comment: Clearing and grading will occur only to the extent necessary to accommodate construction activities. No grading or other site work will occur until a building permit is obtained. "OBJECTIVE 2. Promote the Retention and Preservation of Certain Highly Suitable Areas for Wildlife Habitat and Natural Areas." Comment: Due primarily to the noise impacts created by 1-5, the habitat value of the site is limited. Approximately 32 percent of the site will remain in its natural state. "Policy 1. Strive to Retain Viable Areas of Wooded Hillsides, Agricultural Lands, Wetlands, Streams, and the Green River for Wildlife Habitat." Comment: Clearing of vegetation for buildings, parking lots and landscaping will result in a loss of approximately 68 percent of the vege- tation on site. The site's habitat value is limited by its proximity to 1-5. "OBJECTIVE 3. Recognize the Advantages and Opportunities Afforded by the Topography and Plan its Use Accordingly." Comment: At present, the valley wall at this location provides a contiguous greenbelt between the freeway and residential development above. It is classified in the Data Inventory as a "Major Wooded Area." However, the site is not designated as a greenbelt under the Comprehensive Plan. Because the slope of the property provides unrestricted view from the site over the valley, the proponent proposes residential development which would enjoy the advantage of this view. The topography protects existing views of residents living further to the west. "Policy 1. Discourage Development on Slopes in Excess of 20 Percent" Comment: Slopes of the site are generally on the order of 20 percent, steepening in places to 40 percent. Development of the project site at the densities proposed will require measures to modify and stabilize slo- pes, excepting the 32% of the site to be retained in natural open space. 32 "Policy 2. Preserve the Views of Hillside Residents." Comment: Views from McMicken heights, above 53rd Avenue South, looking east toward Southcenter Shopping Mall and I -5 will be only slightly affected since the proposed building rooflines are at least 20 feet below the finished grade of existing homes west of the site. "Policy 3. Preserve and Promote the Quality of Natural Land Forms." Comment: The cuts and fills necessary to provide stable foundations for buildings and parking areas will substantially alter the existing topography on approximately 68 percent of the site. "OBJECTIVE 5. Strive to Improve the Qualities of the Air to a Level Conducive to a Healthy, Clean Environment." Comment: The proposal will generate additional automobile traffic in the site vicinity. However, the amount of air pollution created by project traf- fic will not cause appreciable deterioration of existing air quality in this urbanized area. (i.e.: I -5, I -405, Southcenter parking lot and Southcenter Parkway). Although no air quality monitoring has been performed in the vicinity for several years, project residents will be exposed to air quality of a highly urbanized area that can have high levels of hydrocarbons and carbon monoxide. These pollutants aggravate conditions associated with asthma, heart and chro- nic lung disease. The State's automobile emission control requirement is reducing automobile - generated pollutants to some extent. "OBJECTIVE 6. Recognize the Characteristics of Local Geology and Consider Them in the Land Use Planning Process." Comment: The site is located on the valley wall. The City's Comprehensive Land Use Plan Map designates the valley wall on the west side of I -5 for Low Density Residential development. The local geology may have contributed to this designation. Factors such as slope stability and existing land use were also considered. The northeast quadrant of I -5 /I -405, which likewise has steep slopes, includes Medium and High Density Residential designations on the Plan map. According to the geotechnical engineers, development of the property as planned is feasible providing that maintenance of the WSDOT drain systems to the level required to maintain or improve present performance is accomplished and that the recommended near - surface drainage measures are accomplished as discussed in Appendix A. Development of the site will be difficult due to the marginal stability and saturation of the near - surface soils. Close coor- dination between the earthwork contractor and the engineer will be required to assure that the recommendations outlined in Appendix A are diligently followed. "Policy 2. Discourage Development in Areas Where Slopes Are Known to Be Unstable. In Areas Where the Stability of Slopes is Questionable, Allow Development Only After a Qualified Professional Can Demonstrate that Slopes Will be Stable Even after Site Modification." 33 Comment: The site is within a large prehistoric landslide zone. Since construction of 1-5, the stability of this property and adjacent proper- ties has been improved by remedial drainage systems installed by WSDOT. The results of the geotechnical study indicate that, with proper design and construction monitoring, the property can be developed in the manner proposed without endangering the stability of the site with respect to either deep- seated or shallow slope movements. These two mechanisms of slope failure are assessed to be basically independent of each other at this site. The existing subsurface drainage facilities installed by the State of Washington are a critical element for protection of the adjacent highway system and satisfactory performance of the WSDOT drain systems is the primary mechanism for control of deep- seated movements. Adequate maintenance of this system is necessary both from the standpoint of public interest and safety with respect to use of the highway and street systems as well as for the continued long -term stability of the project site. Surficial slope movements are largely affected by surface runoff, near surface infiltration of rainfall and runoff, and oversteeping or overloading in the thin mantle of less competent soils that overlies the area. Control of surficial slope movements will be achieved by the installation of various interceptor trench and French drain systems at appropriate locations on the site, temporary drainages systems and per- manent storm drain lines, footing and retaining wall drain systems around the proposed buildings, limiting the size and location of temporary stock- piles, sequencing building construction, controlling cut slope angles or providing shoring /bracing of excavations, and provisions for construction monitoring and instrumentation by the geotechnical engineer. Overall load changes on the property will be relatively small for type of building construction and final grades planned. The net increase in load within the strip of property which will be occupied by the structures, including adjacent yard areas, will be on the order of 300 pounds per square foot, taking into account design building loads and cutting and filling activi- ties. Foundations will, for the most part, be supported on the more com- petent soils represented by Unit B (see geotechnical engineering report, Appendix A). "OBJECTIVE 8. Recognize the Environmental Base Map of the Tukwila Planning Area Which Depicts the Distribution and Extent of Natural Amenities Based on the Previously Mentioned Objectives and Use This Map as a General Planning Guide." Comment: The environmental base map shows the site within areas charac- terized as woodlands and as steep and unstable slopes. The proposed develop- ment will eliminate approximately 68 percent of the existing vegetation and replace it with buildings, parking lots, and ornamental vegetation. The topography of the site will be altered by the cut and fill required to pro- vide building and parking areas. Retaining walls will be necessary to mini- mize potential slope movement. To the extent that the amenity value of the site is its appearance as a wooded hillside between the freeway corridor and residential development to the west, that value will be substantially dimi- nished. 34 OPEN SPACE "OBJECTIVE 1. Provide for an Adequate and Diversified Supply of Open Space and Include Them in an Open Space System." Comment: Construction of the project will interrupt the expanse of undeve- loped wooded hillside above I -5 at this location. Thirty -two percent of the site will remain in its natural state. "Policy 1. Strive to Preserve Steep Hillsides and Wooded Areas in a Scenic Condition. Encourage Replanting and Revegetation of Denuded Areas Not in the Process of Development." Comment: Approximately 32 percent of the site will remain in its natural vegetated state. The remainder of the natural vegetation will be removed and replaced by buildings, parking lots and ornamental landscaping. The proposed landscape plan includes use of ivy, rye and clover, for erosion control. NEIGHBORHOOD OBJECTIVES AND POLICIES "OBJECTIVE 1. Protect All Viable Residential Neighborhoods from Intrusion by Incompatible Land Uses. Comment: Development of this multi - family project, at a density of 15.25 dwelling units per acre within an area otherwise developed with single family nomes, would occur as the result of vesting of the applicant's rights prior to the effective date of the current zoning ordinance. All other property in the vicinity is subject to the current zoning ordinance and therefore can be developed only with single family. uses. As reflected in comment letters on the Draft EIS, many nearby residents believe this project will seriously diminish the character and quality of their neighborhood. "Policy 1. Use Natural Features Like Topography, To Separate Incompatible Land Uses From the Residential Areas." Comment: The slope of the site provides some separation of the project from lower density residential development to the west. The rooflines of the development will range from 4.5 feet above the elevation of pedestrian eye level on Slade Way and 53rd Avenue South west of the site to approxi- mately 44 feet below this elevation. Slopes afford less separation to residential areas north of Slade Way where rooflines range from 12 to 29 feet above pedestrian eye level. "Policy 3. Prohibit Spot Zoning in Established Residential Neighborhoods." Comment: The Tukwila Zoning Code adopted in 1982 zoned the entire site Single Family Residential R -1 -12.0. However, the proponent had applied for a building permit prior to the effective date of the current zoning ordinance and at a time when the site's zoning included Multiple Residence High (RMH) and Low Apartments (R -4) zoning as well as (R -1) zoning. Consequently, the proposed project is regulated by the earlier zoning ordinance and would be a legal non - conforming use. 35 The Multiple family designation was previously deemed appropriate as a transition between the freeway and lower density development higher on the hillside. "OBJECTIVE 2. Minimize the Incompatibilities Between Different Types of Residential Areas." Comment: The proposed development differs substantially in scale, density, numbers of occupants and volume of traffic from nearby single family develop- ment. The relative topographic isolation afforded by the site and proposed vegetation and landscape buffers will minimize some of the project's impacts on the existing residential neighborhood. "Policy 1. Provide for medium density "transition areas" between high and low density residential areas." Comment: The density of the development would be 15.25 dwelling,units per acre which is three to five times the density in the adjoining neighborhoods west, south, and north of the site. No medium density transition area would be provided. However, the gradient change provi- des a partial buffer between the different uses. "Policy 2. Multiple - family developments should be located functionally convenient to a primary or secondary arterial street where traffic generated by these uses does not pass through single family residential areas." Comment: Klickitat Drive, which is a collector arterial, is the only designated arterial in the immediate vicinity. It connects 51st Avenue South, north of SR 518 and Southcenter Parkway. According to the Valley View Estates Traffic Impact Analysis, approximately 38% of the project's daily traffic would travel west through existing single family areas on local residential streets (e.g., South 160th Street and 51st Avenue South). However, none of the local streets would experience significant adverse impacts on roadway capacity. "Policy 3. Promote Implementation of Corrective Measures by Existing Multiple - Family Developments where -such developments adversely impact adjacent and viable single family neighborhoods." Comment: The proponent feels that the proposed project, due to the topography of the site and those mitigating measures proposed by the applicant, does not pose an adverse impact to single family neigh- borhoods in the vicinity of the site. The City may determine that additional mitigating measures are appropriate. OBJECTIVE 3 "Policy 1. Encourage the use of vegetative or fence -like screens adja- cent to freeways and along noise use district to protect residential areas from high noise levels." 36 Comment: Most exterior areas of the proposed development would experience noise levels characterized by EPA as having significant adverse impacts. The site plan has been revised to place the children's play area in the southwest section of the property where residential structures may provide some attenuation of noise from freeway traffic. Previously, an eight -foot high fence had been pro- posed for the children's play area located in the northeastern corner of the property nearer to the freeway. This fence would have reduced average noise levels in the play area 10 dBA to about 55 dBA or less, which is the minimum level for preventing noise - induced speech inter- ference and annoyance outdoors. Should the site now proposed for the play area be deemed infeasible (according to City standards) relocation of the play area and fencing may be required to provide noise atte- nuation consistent with EPA standards. Other outdoor recreation areas are not proposed to be fenced, and would continue to experience adverse noise levels. Vegetation on site provides only a slight reduction of 1 -5 freeway noise. The proposed development will provide a slight reduction in I -5 freeway noise for properties west of the site which will compensate for the permanent loss of trees on the site.. "Policy 4. Encourage a minimum care and maintenance level for undeve- loped open space." Comment: The undeveloped open space area on the site (2.3 acres) will remain in its natural state and be maintained by the Homeowners Association. "Policy 5. In addition to parking space for tenants, encourage the provision of adequate parking space for guests and recreational vehicles within multiple - family developments." Comments: The project would provide 182 parking spaces adjacent to the units for a ratio of 1.7 spaces per dwelling unit, which is consistent with the City's Zoning Code requirements. According to the Traffic Report, this amount of parking would be adequate to meet projected demand, even during most peak periods. However, the consultant recom- mended that no parking of recreational vehicles be allowed on the site in order to maintain needed flexibility between resident and visitor parking. "Policy 6. Encourage the development of pedestrian rights -of -way; overpasses and well - lighted trails which can provide safe passage from residential areas to commercial, service and recreational areas." Comment: The site is not within walking distance of commercial uses. (Southcenter Mall's location across I -5 is not considered within walking distance). Pedestrian and bicycle access between the site and existing and proposed recreational areas is poor. By City ordinance, sidewalks will be required along street frontages abutting the site. In addition, the traffic consultant has recommended widening the shoulder along South 160th Street to a minimum of four feet to facili- tate safe pedestrian access in the area. 37 "Policy 7. Encourage the provision of recreational open space within multiple - family developments." Comment: The proposed development would include over 200 square feet of recreational area per dwelling unit totaling 23,400 square feet. A 6,175 square foot children's play area also would be provided. As noted, the adequacy of proposed recreational areas will be evaluated during review of the proposed grading plan. HOUSING OBJECTIVES AND POLICIES OBJECTIVE 1. "Policy 1. Encourage Housing Developments which provide a diversity of housing types." Comment: The 18 residential buildings proposed each will contain six dwelling units, including two two - bedroom townhouses, two one - bedroom flats and two one - bedroom townhouses or efficiency units. "Policy 2. Encourage the development of owner occupied multiple- family residential uses." Comment: The proposed residential development may or may not be sold as owner - occupied condominium housing. Even if sold as condominiums, purchasers would have the option of leasing or renting the units rather than residing in them. OBJECTIVE 2. "Policy 2. Enforce building code regulations in all residential areas." Comment: The proposed project will be subject to City of Tukwila Building Division review following SEPA review. This review may include additional investigation of site conditions and imposition of mitigating measures. - "Policy 3. Encourage the use of noise insulation materials in the construction of residential structures in areas which are seriously impacted by freeway or aircraft noise." Comment: The site is seriously impacted by freeway noise. Project development will include noise insulation materials in the construction as described under mitigating measures in the Noise Section of this FEIS. The Noise Study indicates that with proposed mitigation, interior sound levels will far exceed EPA's recommended standard when windows are open. Therefore, a potential mitigating measure is installation of forced -air ventilation to eliminate the need for open windows. 38 "OBJECTIVE 4. .Encourage incorporation of crime reducing elements into the residential developments in the planning area." Comment: The developer will work with the City of Tukwila's Crime Prevention Officer during the building plan stage to incorporate crime - reducing features. The project's off - street parking will reduce the potential for vehicle and pedestrian accidents, auto thefts and car prowl incidents often associated with on- street parking. See further discussion of this issue in the discussion of Police protection later in this FEIS. "Policy 1. Encourage housing design in which building forms and spaces allow residents to adopt proprietary attitudes beyond their normal living spaces. Discourage housing designs which cause anonymity among residents and foster feelings of helpless isolation." Comment: The proposed development will create eighteen six- plexes. Buildings will be oriented in a linear pattern to take advantage of the view to the east. This site plan design may afford less orientation of individual residential buildings to other buildings on site and less interaction among residents. "Policy 2. Encourage housing designs which provide for the visual sur- veillance of public space both from the dwelling units and the street." Comment: The children's play area may be visible from the top two stories of most buildings. The top two stories of the units will also have views of the parking lot. The parking lot will be screened from the street by existing vegetation. "Policy 3. Encourage the adequate lighting of residential streets and parking lots." Comment: Parking lot and driveway lighting will be subject to City approval. See Light and Glare section of this FEIS. TRANSPORTATION OBJECTIVES AND POLICIES OBJECTIVE 1. Establish an efficient, safe, and well- designed circulation system which promotes desired development patterns." Comment: The Traffic Report indicates the existing roadway system has the capacity to accommodate the increase in traffic that would be generated by the proposed development. The 53rd Avenue South /Klickitat Drive intersec- tion has experienced an accident rate which could be reduced with a left - turn lane and construction of such a lane has been proposed in connection with this project. Traffic and pedestrian accidents can be expected to increase in proportion to the increase in traffic volume resulting from the development. In order to facilitate safe pedestrian access from the project site to 51st Avenue South (i.e., to the school bus stop and other uphill destinations), the traffic consultant has recommended widening the shoulder along South 160th Street between the site and 51st Avenue South. The traffic consultant noted that although the level of service of streets 39 in the vicinity may not be adversely affected by the project, residents will perceive the increased traffic flows as a negative impact, par- ticularly since a significant proportion of project trips will travel through residential areas to the west. "Policy 1. Minimize conflict between moving traffic and parked vehicles." Comment: The proposed supply of on -site parking should minimize the potential for on- street parking. The proposed parking design will pro- vide 1.7 parking stalls per dwelling unit. "Policy 2. Discourage the maneuvering of automobiles or trucks on public rights -of- way." Comment: The proposal will not contribute to automobile maneuvering on public rights -of -way. "Policy 10. Encourage the construction of safe internal access roads in developments and other private easement roads." Comment: The proposed driveway locations should have adequate visibi- lity of the adjoining streets. One driveway located on Slade Way will have a dead end with a hammerhead turnaround. The other driveway on Slade Way will have through access to 53rd Avenue South Several design features have been proposed by the traffic consultant for the internal access road to minimize pedestrian /vehicle conflicts, such as speed bumps and a separate pedestrian walkway. (See the revised Transportation Section of this FEIS.) "Policy 11. Encourage the use of noise buffers between major roads and residential areas." Comment: No noise barriers are proposed between the buildings and I -5. The children's play area has been relocated to a location where on -site structures could provide some attenuation of freeway noise. This loca- tion has been proposed as an alternative to a location requiring an eight foot high solid continuous fence around the eastern half of the proposed children's area to reduce noise levels by about 10 dBA, to 55 dBA or less, which is a generally acceptable level according to EPA's Noise Guidelines. Other exterior spaces, such as the proposed recreation areas, would not have the benefit of noise barriers and would be exposed to continuous noise levels characterized by EPA as having significant adverse impacts. TRANSIT "Policy 1. Coordinate with METRO for the best and most useful transit service for local citizens within the planning area." Comment: The vicinity is currently well- served by existing METRO Transit routes. One route passes directly adjacent to the site on 53rd Avenue South, with stops on South 160th Street. The developer will 40 work with METRO to ensure a safe convenient bus stop location for pro- ject transit patrons adjacent to the Valley View Estates site. "Policy 2. Support efforts to increase transit use." Comment: See response to Transit Policy 1. SIDEWALKS /PATHWAYS "Policy 1. Create a sidewalk or pathway system where every link is a part of an integrated network." Comment: Due to the topography and lack of pedestrian- oriented activi- ties in the vicinity, sidewalks have not been constructed in this area in the past. However, the City's 1984 -1989 Transportation Improvement Plan proposes sidewalks for area streets and, by City ordinance, the developer will be required to install sidewalks along the sides of public streets abutting the project site (i.e. Slade Way and 53rd Avenue South). In addition, the traffic consultant has recommended widening the shoulder along South 160th Street between 53rd Avenue South and 51st Avenue to Facilitate safe pedestrian access in that area. "Policy 2. Integrate bicycle, pedestrian, bus and street systems and develop accommodating and safe mechanism of transferring from one mode of transportation to another." Comment: The developer will meet with METRO Transit to ensure a safe and convenient bus stop location for project transit patrons adjacent to the site. By City ordinance, sidewalks will be required adjacent to the site along public streets (i.e. Slade Way and 53rd Avenue South). No sidewalks are proposed along South 160th Street which currently pro- vides access to the school bus stop on 51st Avenue South. However, widening of the shoulder along South 160th Street between 53rd Avenue South and 51st Avenue South has been recommended by the traffic con- sultant. The site is not in the vicinity of any designated bicycle facilities. "Policy 4. Design the sidewalk or pathway system to allow use by the elderly and handicapped." Comment: Six of the dwelling units will be designed as handicapped units. Parking and sidewalks adjacent to those units will meet the standards of An Illustrated Handbook for Barrier Free Design." As noted in the response to one of the comments on the DEIS, a wheelchair ramp could be provided to the on -site play area. "Policy 5. Encourage the location, design and maintenance of pedestrian sidewalk or pathway systems to provide security for abutting property owners." Comment: Abutting properties are presently undeveloped. By City ordi- nance, sidewalks will be required adjacent to the site along roads which abut the site: i.e., Slade Way and 53rd Avenue South. "Policy 8. Provisions should be made in each sidewalk or pathway constructed to provide for the safety of the user." Comment: Required sidewalks will meet City standards. UTILITIES OBJECTIVES AND POLICIES STORM WATER SYSTEM "OBJECTIVE 6. Provide an adequate and cost - effective method of preventing property'damage from local storm water." Comment: Construction of the proposed development would not alter existing drainage basin boundaries. Changes in potential peak flow of, storm runoff due to building construction and paving may be controlled by the drainage retention and runoff system; alternately, drainage facilities . may designed for direct discharge into the Green River. "Policy 1. Design the storm water systems to handle the flow of peak runoff." Comment: If a stormwater detention system is selected, it will be designed for a 10 -year storm. Stormwater would be stored in under- ground storage pipes designed for a 10 -year storm. The gravity flow system would be designed to discharge storm water at the same rate as . the existing discharge rate. If direct discharge of stormwater is incorporated into the drainage . plans, stormwater would flow directly to the Green River through a series of downslope pipes and open channels. This would eliminate the potential for leakage from the detention structures and reduce the level of excavation and disturbance of the hillside. "Policy 2. Encourage a part structural (pipe), part non - structural (detention pond) storm sewer system." Comment: As previously stated, storm water detention system for a 10 -year storm may be constructed to control storm water discharge at the sarne rate as the existing discharge rate. Alternately, drainage facilities may be designed for direct discharge into the Green River. "Policy 3. Coordinate with King County to insure that Tukwila's Storm water System will be able to accommodate upland flows." Comment: A stormwater system designed in accordance with City of Tukwila requirements and the recommendations and requirements detailed in the geotechnical engineers report is proposed. The City of Tukwila must approve stormwater drainage plans prior to issuance of the building permit. 42 The site drainage basin is bounded by Slade Way, 53rd Avenue South and the extension of South 158th Street. The site drainage basin area is 7.2 acres and is divided into two sub basins, the south being 4.4 acres and the north 2.8 acres. Drainage from the site now flows directly to the Green River through a series of downslope pipes and open channels. The project stormwater design will either limit off -site storm water discharge to the same rate as the existing discharge rate or provide for direct discharge into the Green River. Off -site flow from approxi- mately 12 acres west of Slade Way and south of South 160th Street is intercepted and transported through the site via an existing storm sewer shown on the site utility plan on Figure 16. Part of the system parallel to 53rd Avenue South runs above ground and is leaking (observation 10/17/83), causing some ponding in the immediate area. A portion of the existing system would be abandoned and replaced by a new storm line as shown on the site utility plan and the existing storm line that is above ground would be repaired. "Policy 4. Where beneficial to downstream properties, control peak flow runoff from the source at a rate similar to natural conditions." Comment: If required by the City of Tukwila and WSDOT, storm water discharge will be controlled so as not to exceed the existing discharge rate for up to a 10 -year storm. "Policy 6. An equitable fee should be established charging the costs of the storm water system to the user and those benefiting from the system." Comment: Fee requirements for use of existing storm water systems will be determined by the. City of Tukwila during its review of the propo- nents stormwater drainage plans. As a condition of grading and building permit issuance, the City of Tukwila will require that formal agreements by reached between the developer and the State of Washington regarding long term commitments for monitoring maintenance and repair of new and existing drainage facilities that may affect the stability of the project site. Included within the mitigating measures listed for water resources are the drainage facilities and measures that will be provided at the expense of the developer. "OBJECTIVE 7. Coordinate with other jurisdictions and agencies for solu- tions to storm water control in the Green River Watershed." Comment: The proponent will coordinate with other jurisdictions and agen- cies as required by the City of Tukwila prior to approval of the project stormwater drainage plans. 43 "Policy 1. Encourage control of peak runoff at the source." Comment: Peak runoff will either be controlled so as not to exceed the existing discharge rate or the drainage facilities will be designed for direct discharge to the Green River. "Policy 3. Consider non - structural as well as structural solutions to storm water control." Comment: If required by the City of Tukwila, a detention pond designed for a 10 -year storm will be used to control runoff at the site and reduce peak runoff rates. UNDERGROUND UTILITIES "OBJECTIVE 8. Encourage the undergrounding of all existing and new overhead electrical and communication systems." Comment: All utilities to the buildings will be installed underground. "Policy 3. Encourage all undergrounding to occur in existing easement or rights -of -way whenever feasible." Comment: New easements will be required for sewer, water, electrical• and telephone lines. "Policy 4. Vaults associated with undergrounding should be sited unobtrusively where they do not inhibit the safety of adjacent roadways." Comment: Vault location has not yet been determined. There appears to be sufficient room for vaults away from the roadway. City approval of vault location will be made at the building permit stage. "Policy 5. Promote the use of one trench in a corridor to accommodate all electrical and communication utilities." Comment: The developer will consolidate utilities to the extent possible in order to facilitate their repair, minimize the amount of area disturbed, and reduce installation costs. "Policy 6. The City should establish procedures to implement under- ground connections to facilities served by underground utilities." Comment: All utility connections will be made underground. "Policy 7. Encourage a minimum of disruption of areas affected by the installation of underground utilities." Comment: Some minor disruption including cutting of alder trees, will occur when utilities are installed. However, alder reestablishes itself rapidly, so the impact on affected areas will not be signifi- cant. 44 1 City of Tukwila Comprehensive Plan Summary The most significant Goals, Policies and Objectives of the City of Tukwila's Comprehensive Plan with respect to the proposed condominium development are those relating to: 1) protection of steep slope areas; 2) preservation of natural amenities, such as major wooded areas; 3) protection of established single family neighborhoods from incompatible land uses; 4) provision of ade- quate and safe transportation facilities; 5) use of noise screens or barriers to protect residential areas from freeway noise. levels; 6) adequacy of drainage facilities to protect off -site properties; and 7) adequacy of recreation areas. Evaluation of the proposal's overall compliance with these policies depends in large part on commitments by the developer to appropriate mitigation measures. As has been pointed out in the discussion of individual policies, the proposal would substantially alter the topography and wooded character of the site despite proposed mitigation measures. However, the site has not been designated as a greenbelt under the Comprehensive Plan and thus there is no guarantee that it would otherwise remain undeveloped. The more critical issue from a public health and safety standpoint, as well as an environmental standpoint, is the stability of the hillside. Several policies and objec- tives, such as the policy which discourages development on slopes over 20%, are intended to prevent hazardous development situations. According to the geotechnical reports prepared in connection with this project, the hillside's stability will depend upon the long -term maintenance of the Department of Transportation's (DOT) deep- drainage facilities, as well as on other mitiga- tion measures proposed by the applicant. The scale and density of the proposed development will differ substantially from the character of the surrounding area, which is exclusively zoned (and largely developed) for single family uses. Thus the proposal does not sup- port Comprehensive Plan policies that seek to maintain the integrity of established single.family neighborhoods. However, the applicant has a vested right to processing of this multi - family proposal, due to the multi- family zoning which existed on the property at the time the application was filed with the City. At the same time, the City has the authority to impose those mitigation measures which are deemed necessary to minimize impacts on nearby single family homes, including certain traffic improvements. The Traffic Report on this project indicates that neighboring streets have adequate roadway capacity to accommodate projected traffic from the develop- ment. However, the project will generate traffic through single family areas on local residential streets which is discouraged by the Comprehensive Plan. The Traffic Report acknowledges that pedestrian access in the area is poor, due to limited roadway shoulders and the lack of sidewalks. Although no off - site sidewalks are proposed as part of this project, sidewalks are proposed for the area as part of the City's 1984 -89 Transportation Improvement Program. By City Ordinance, sidewalks will be required along the project site's south, west and north boundaries (i.e., along portions of Slade Way, 53rd Avenue South, and. the access road off 53rd Avenue South). The 53rd Avenue South /Klickitat Drive intersection would benefit from installation of a left -turn lane and construction of a turn lane has been proposed as a miti- gating measure. 45 The Comprehensive Plan policy which promotes the use of vegetation or fences to protect residential areas from high freeway noise levels is especially relevant to this project. While the proposal would locate the children's play area at a site partially screened from freeway noise by the residential buildings, other outside areas, including the proposed recreation areas, would be exposed to constant noise levels which EPA Guidelines characterize as having "significant adverse impacts." Thus the City of Tukwila may require fencing of other exterior areas to bring this proposal into closer compliance with the Comprehensive Plan. All proposed recreational areas will be evaluated during subsequent City review of the project. Existing grades suggest that some designated recreational areas may be too steep to adequately satisfy City standards for these uses and may need to be revised. This determination will be made once a grading plan has been submitted for the project. In summary, this development proposal presents several conflicts with Comprehensive Plan policies. Some of these conflicts, which stem from the fact that the project is vested under earlier zoning, cannot be mitigated. other conflicts with the Comprehensive Plan can be minimized through the implementation of appropriate mitigation measures. 2. City of Tukwila Zoning Code Although the current Tukwila Zoning Code, which was adopted in 1982, zoned the entire site Single Family Residential R -1 -12.0, the proponent had applied for a building permit prior to the effective date of this zoning ordinance at a time when the site carried three zoning classifications: Multiple Residence High (RMH), Low Apartments (R -4), and One Family Dwellings (R -1). Consequently, the proposed project is regulated by the use and development regulations'of the earlier zoning ordinance. Please refer to Appendix C for descriptions of the RMH, R -4 and R -1 Districts. As a result of the R -1 zoning of the project site in 1982, the proposed development would constitute a legal non - conforming use as provided in the 1982 Zoning Code. Under the site's prior (and current applicable) zoning, approximately 2.9 acres of the north portion of the site were zoned RMH. The southeast 2.5 acres were zoned R -4 and southwest 1.7 acres were zoned R -1. The R -1 portion of the site is consistent with the new Zoning Code designation. The project may not meet City standards for recreational areas, depending on the final grades proposed for the site (see 1, above). 3. Highline Community Plan and 1964 King County Comprehensive Plan The site is within the area addressed by King County's Highline Community Plan which governs unincorporated parts of King County slightly to the west and south of the subject site. The Highline Community Plan map designates the project site and surrounding area as Single Family Residential, four to six dwelling units per acre. This recommended density is similar, though slightly higher, than the City of Tukwila's Comprehensive Plan designation for the area. Like the City's Comprehensive Plan map, the Highline Community Plan map designates part of the project site as a steep slope area where spe- cial development controls are deemed necessary. 46 S 160th St R -1 -12.0 R -1 -9.6 NORTH R -1 -12.0 1-•■■•I 47 SOUTHCENTER C -P trander Blvd LEGEND R -1 -9.6 SINGLE FAMILY RES. R -1 -12.0 SINGLE FAMILY RES. R -3 R -4 RMH 'THREE & FOUR FAMILY LOW APARTMENTS MULT RES HIGH DENSITY C 71 COMMUNITY RETAIL BUSINESS C -2 REGIONAL RETAIL BUSINESS C -P PLANNED BUSINESS CENTERS ZONING FIGURE 5 R.W. THORPE AND ASSOCIATES II1. EXISr1NG CONDITIONS, IMPACTS AND MITIGATING MEASURES A. INDEX OF ELEMENTS uF THE ENVIRONMENT ELEMENTS uF THE PHYSICAL ENVIRONMENT Earth' Geology 51 Soils 51 Topography 60 Unique Features 54 Erosion 61 Accretion /Avulation NA Air Quality 62 Odor 65 Climate 66 Water Surface water movement 66 Surface Water quantity 66 Surface water quality 66 Runoff /absorption 66 Floods !NA Groundwater Quantity 71 Public water supplies 122 Flora Number or diversity of species 77 Unique species 77 Agricultural crops NA Fauna Number or diversity of species 79 Unique species 79 Fish or wildlife habitat ,NA Noise 79 Light and Glare 88 Land Use 89 Natural Resources 93 49 Rate of use 93 Nonrenewable resources 93 Risk of Explosion or Hazardous Emissions NA ELEMENTS OF THE HUMAN ENVIRONMENT Population 94 Housing 94 Employment NA Transportation /Circulation Vehicular transportation generated 96 Parking facilities 106 transportation systems 107 Movement /circulation of people and goods 107 Waterborne, rail and air traffic NA Traffic hazards 109 Public Services Fire 111 Police 112 Schools 113 Parks and other recreational facilities 114 Maintenance 119 Other governmental services NA Energy Amount required 120 Source /availability 120 Utilities Energy 120 Communications 121 Water 122 Sewer 123 Storm water 66 Solid waste 125 Aesthetics 126 Human Health 132 Archaeological /historical 134 Economic Factors 134 50 III. EXISTING CONDITIONS, IMPACTS AND MITIGATING MEASURES B. ELEMENTS OF THE PHYSICAL ENVIRONMENT Earth Geology and Soils Existing Conditions A geotechnical analysis of the site has been conducted by the soils engi- neering consultants (GeoEngineers, Inc.). A copy of the report has been included as Appendix A to the EIS and should be referenced for a complete understanding of site conditions and geotechnical conclusions and recommen- dations for the project. The site is located within a very large, prehistoric, landslide zone. A substantial portion of property was involved in a landslide that occurred in 1960 -1961 as the result of excavation of borrow materials used for fill in the Andover Industrial Park. The approximate limits of the slide are indi- cated on Figure 2 in Appendix A to the EIS. Since construction of Interstate highway 5, the stability of this property and adjacent properties has been improved by the remedial drainage measures which were installed during freeway construction and are maintained by the Washington State Department of Transportation (WSDUT). The 1960/61 slide movement resulted from the combined effect of excavation and the substantial artesian pressures existing in a waterbearing sand layer. The remedial measures considered were based on reducing the hydrostatic pressure within the waterbearing sand layer which appeared to immediately underlie the failure surface. Deep vertical wells as well as horizontal drains and drainage trenches were considered. A series of horizontal drains was installed in the summer of 1961, together with some regrading of the borrow pit area. A plan from a Shannon & Wilson 1964 report showing the locations of the horizontal drains is presented in Figure 3 of Appendix A to the EIS. Altogether, 20 six -inch 'diameter slotted pipe drains with lengths from 100 to 150 feet were installed. Eight of the drains were located along the toe of the roadway f i l l in the southwest corner of the site, while the remainder were located in the south - central portion of the site. The flow from the drains does not appear to be piped and is probably responsible for some of the existing wet areas at the site. The wSDOT remedial measures consisted of an extensive subsurface drainage system of vertical wells tied into horizontal drains and cylinder pile wall retaining structures as shown in Figure 2 of Appendix A to the EIS. In addi- tion, an interceptor drain, shown as the D -3 drain on Figures 2 and 3 of Appendix A to the EIS, was installed on an easement extending into the west - central portion of the project site. The D -3 drain constitutes a shallow drain system and flows by gravity into a paved interceptor ditch which carries flow in a southeasterly direction to a natural drainage channel near the southern end of the project site which leads to the valley floor. 51 The WSDOT drainage system consists of a series of five -foot diameter wells, drilled in groups of three, tied into horizontal drains originating at the retaining wall along Klickitat Drive. The wells are located just east of the site. In addition to the large diameter wells, a number of small diameter (six to nine inch) vertical drains were installed in between the large wells as shown in Figure 2 of Appendix A to the EIS. Initially, the large diameter wells were pumped to lower the ground water level in the deep artesian aquifer. Subsequently, a cylinder pile wall was constructed along Klickitat Drive and horizontal drains were installed to intercept the deep wells so that they now function with the drains as a gravity flow system. It appears the horizontal drains consist of 12 -inch diameter, unperforated plastic pipe with ten foot long stainless steel well point tips. Information including elevations, grades and lengths of the WSDOT horizontal drain and vertical well system, is presented in Table B -4 in Appendix A to the EIS. Based on a recent inspection of the wells, it appears that the original pumps are still in place in approximately 70 percent of the wells. The pumps and outlet pipes have been removed in the other wells. The condition of the in -place pumps is not known. Inspection of the outlets of the horizontal drain system revealed 42 outlets through the cylinder pile retaining wall along Klickitat Drive. The length and orientation of any drains in these outlets other than those that lead to the wells is unknown. These may be short horizontal drains to drain the area immediately behind the wall or replacement drains to the wells. The extra outlets may also be weepholes to drain the zone behind the wall. Approximately half of the 42 drain outlets, primarily to the north, were dry at the time of a recent visit (April 12, 1985). Flow through the other weepholes varied from a drip to about one gallon per minute. There was also significant flow between the wall panels was estimated to be four to six gallons per minute. The primary purpose of the deep drainage facilities is to collect the flow from the artesian aquifer so that excess hydrostatic head pressure does not develop beneath the area of past instability and so that uncontrolled seepage does not exit the toe of the hillside in the vicinity of Klickitat Drive. The installation and function of this and other drainage facilities installed by the State of Washington as part of the I -5 construction project is more fully described in a document entitled "Summary Report, Soil Conditions, and Earth Movements, Vicinity of the Tukwila Interchange" prepared by Shannon & Wilson, Inc., and dated June 21, 1968. The 1968 Shannon & Wilson report also identifies a system of original test drains that were installed by WSDOT just east of the eastern property line and south of the horizontal drain /vertical well system. The soils engineer's recent examination of the portions of this drain system still in evidence indicated that they are still at least partially functional. These drains consist of 12 -inch diameter slotted PVC pipe. The outlets are connected to buried manifolds, three of which discharge into a drainage gully. The fourth manifold was not located. Approximately 60 percent of the drains were located, of which approximately 20 percent appear to be damaged and in need of repair. Local sloughing and erosion has occurred at the drain outlets in several places. Flows from the three manifold outlets-ranged from approxima- tely 0.25 to three gallons per minute. 52 Some evidence of near - surface movement, mostly in the form of shallow creep and flow slides, was noted in the soils engineer's examination of the site prior to preparing their consultation report of May 3, 1982. A scarp was observed a short distance east of Slade Way. The scarp is about 200 feet long and varies from about 12 to 20 inches in height. The downslope extent of the slide appears to be limited to the upper portion of the property in which no general construction is planned. The slide was estimated to have occurred in 1981 or earlier, based on the extent to which vegetation had reestablished itself along the scarp. There are three benches on the site that appear to be manmade (see following "Topography" section). The presence of the benches may be indicative of remedial grading and installation of drainage measures following previous slide activity. Wet surface conditions were observed over much of the site during field explorations in October 1983. Some of these appear as seeps or springs, possibly originating from the horizontal drains installed in 1961, as shown in Figure 3 of Appendix A to the EIS. Subsurface conditions were explored at the site of GeoEngineers, Inc., by drilling eight borings. The records of borings taken previously in 1960 and 1961 were also examined. The borings show a consistent sequence of soil stratification across the site. Variations in the thickness of localized areas of fill and in the near - surface native soils can be expected. These variations are not expected to be significant in terms of impact on construc- tion methods or surficial site stability. Construction monitoring by the geotechnical engineer will provide the means for identifying any variation in soil conditions and advising on any adjustments in site drainage or slope retention modifications that will be required. Three major soil units were identified as follows (Please refer to the Geotechnical and Hydrological Study in Appendix A.) UNIT A (Upper Layer): Fill and /or slope debris, probably native to the site and consisting of loose to medium dense silty fine to medium sands. Thickness varies between five and ten feet. UNIT B (Middle Layer): Gray silt interbedded with fine to medium sand. The gray silt varies in consistency between medium stiff to very stiff, generally becoming stiffer with depth. The silt has some zones which contain a trace to some clay. Slickensides are present throughout the unit as well as ran- domly oriented contacts between different gradations of materials. The sand layers appear to vary from 1/8 of an inch to one to two feet in thickness and are generally saturated. UNIT C (Lower Layer): Gray sandy silty gravel and gray gravelly sand with some silt. Consistency varies from dense to very dense and the unit is generally saturated. Unit B generally grades into Unit C and is separated by a layer of gray fine to medium silty sand in some of the borings. 53 The three units vary significantly both in depth and elevation across the site. As shown in a typical cross section in Figure 4 of Appendix A to the EIS, the units tend to follow the existing topography and slope down to the east. The thickness of the gray silt (Unit 8) is less toward the south (25 feet in Boring C) and increases to the north (89 feet in Boring K). The dip of the surface of Unit C is to the northeast and may represent an erosional feature that occurred before deposition of Unit B. Slope Stability. The deep- seated stability of the hillside was evaluated by the geotechnical consultants by considering the different topographic and ground water con- ditions that existed during the 1960 -61 slide and which existed in March 1985. The alignment of the section judged to be most critical of those ana- lyzed is shown on Figure 1 of Appendix A to the EIS. The first set of analy- ses was conducted by assuming topographic and water level conditions recorded in 1960 and 1961 and back calculating the soil strength parameters required to yield a static factor of safety of 1.0. The soil parameters were then used to analyze the slope stability for the March 1985 topographic and water level condition. The results of these ana- lyses indicate that the static factor of safety of the hillside for March 1985 conditions is in the range of 1.5 to 1.6 for the sections analyzed. The increase in factor of safety is, in the opinion of the geotechnical con- sultant, primarily due to the decrease in water levels caused by the WSDOT drain systems. A static factor of safety of 1.5 to 1.6 represents an accep- table safety factor in relation to the planned project, and generally implies a low risk of static slope instability. The stability of the hillside was also evaluated for earthquake conditions. The seismic loading was approximated in the analysis by an equivalent static force proportional to a nominal horizontal ground acceleration (pseudo static method). For the project area, a horizontal ground acceleration of 0.15g, where g is the acceleration due to gravity, was assumed. It should be understood that the factor of safety calculated using the pseudo static method has a different connotation from that for static loading. Specifically, for the soil conditions which underlie the project site, a fac- tor of safety of one or less represents a very high risk of sliding only during the ground shaking period. When the shaking ceases, movements should effectively also cease. This correlates with the observations of movements reported by a local resident upslope of the site after the 1965 earthquake. The actual amount of straining or displacement will depend on specific site and earthquake characteristics as well as the soil and ground water con- ditions. A dynamic factor of safety of 1.13 was computed using the indicated earthquake loading and undrained strength parameters that would exist during short -term cyclic loading. This value is considered, in general practice, to provide a level of risk comparable to a factor of safety of 1.5 for static conditions. Slope stability due to shallow- seated sliding was evaluated using an empirical /infinite slope approach. This approach is based on reviewing existing slopes at the site and then analyzing different water level con- 54 ■•••••■• •••••-•,•1■11•■••• MIME ONO WM VIIIMI• LEGEND sal 0 - 20% 20 - 30% 30 40% 40% & Above S 160th St 0 ! I ! a Figure 6 • a STEPAN & ASSOCIATES, Inc. 55 SLOPE ANALYSIS %way View Estate, • v1111 N. IUK. - 0111310 _, OM _ _ . INA.. _ VI Alf air ditions, assuming a uniform infinitely long slope of similar materials. Slope configuration at the site vary from about 2:1 to 4:1 (horizontal to vertical). Perched water levels (upper regime in Units A and (3) are variable across the site, ranging from the surface in areas below springs or flow from old horizontal drains to nine feet or deeper. In some areas evidence of sur- ficial creep, as expressed by bending in tree trunks as they have grown on the flatter but wetter slopes, indicates a lesser degree of stability than steeper, well- drained slopes on the site. The importance of control of water levels on near - surface stability is illustrated using a 3H:1V continuous slope, the soil strength assigned to the upper soils in the analysis of deep- seated stability and varying the perched water levels. The effect of water level conditions on the static factor of safety against sliding is shown below: Perched Water Level Static Factor of Safety at ground surface 6 feet below ground surface i2 feet below ground surface 0.7 1.1 1.4 The recommended final slopes for the site are 3H :1V or flatter. It is the conclusion of the geotechnical consultants that the stability of the sur- ficial slopes can be maintained at acceptable levels, provided that adequate drainage of the slopes is accomplished. The actual building loads are expected to have a small favorable effect on shallow slope stability. Dynamic loading during an earthquake decreases the stability of slopes and may result in movement of any marginally stable surficial slopes around the perimeter of the project. As previously described, any movement should be limited to the duration of the earthquake. Resistance to sliding of indivi- dual onsite structures requires analysis on a site - specific basis. This ana- lysis will be conducted by GeoEngineers, Inc. and the appropriate corrective measures recommended for inclusion in the design during the preparation of the final plans. Impacts Construction of the proposed development will require clearing and removal of vegetation, cutting, limited filling, and reworking of soils to varying depths. The greatest depths of excavation are expected in building areas and certain segments of utility trenches. The geotechnical consultant concludes that development of the property as planned is feasible providing that maintenance of the WSDOT drain systems to the level required to maintain or improve present performance is accomplished throughout-the project life and that the recommended near - surface drainage measures are implemented and maintained. Development of the site will be difficult due to the marginal stability and saturation of the near - surface soils. Close coordination between the earthwork contractor and the soils engineer will be required to see that soils recommendations are diligently followed. 56 There are two principal mechanisms of slope instability which could affect the property. These include deep- seated sliding in a zone of soil from 30 to 50 feet below the existing surface and surficial sliding in the upper unit of soil that generally extends to a depth of about 10 to 12 feet below the existing ground surface. The potential for movement of the hillside in the deeper zone of soils is largely controlled by the continued satisfactory performance of the WSDOT vertical well /horizontal drain system which was installed during construction of Interstate Highway 5. It is also controlled to a lesser degree by the "Original Test Drains" which were installed south of the vertical well/ horizontal drain system. From a review of available information, it appears that the overall site stability in the approximatelye20 years since these drains were constructed has been good and that the drainage system continues to be generally effective in preventing deep- seated movements. It is of prime importance, however, that both of the WSDOT drain systems remain fully operational. If the drainage systems should deteriorate so that artesian pressures can again increase beneath the hillside, the risk of deep- seated and extensive earth movements can be expected to significantly increase. The second mechanism of shallow- seated movements is largely affected by sur- face runoff and near - surface infiltration of rainfall and runoff from higher ground. Based on the approximately 200- foot -long scarp that was observed in 1982, considered to be indicative of recent movement, it is evident that this potential for surficial movements is still relatively high in the southern portion of the property. Control of surface runoff and near surface seepage is a significant factor in maintaining the stability of the shallow surficial soil unit. Installation of various subsurface drains and collection of sur- face runoff in a controlled manner is the primary means by which surficial sliding will be controlled. The types of drainage facilities to be installed include an interceptor trench along the western property line, surface drains, a gully French drain, parking area French drains, subsurface wall drains and downspout drains. The impact of building loads on overall slope stability was evaluated and found to have a negligible influence on the factor of safety. The possibi- lity of a decrease in the factor of safety with a rise in the water level resulting from deterioration of the WSDOT drainage systems was also eva- luated. The results of this evaluation indicate that the risk of sliding would become very high, i.e. FS = 1.0, if the water table were to rise an average of 20 feet above the March 1985 levels in the lower artesian aquifer (reference Tables B -1, B -2 and B -3 in Appendix A of the EIS). There may be some destabilization of slopes during construction if slopes are oversteepened or adequate shoring is not used. Remedial measures, including temporary backfilling, buttressing or otherwise increasing toe resistance, will have to be initiated as required. Earthwork on this property will be very difficult. The consultant also recommended that grading be undertaken during the late summer -early fall months when the least amount of rainfall can be expected and surface runoff and seepage in the upper soil units should be diminished. Construction acti- vities will be scheduled so that site grading, drainage installation and sur- 57 face stabilization are completed in any given area within a single construction season. Construction will also be phased to minimize the impact in any one area. No area should be left partially graded or without proper surface drainage, as this may endanger the near - surface stability of that portion of the site if left through the wet season. The ability to use the on -site soils for fill is expected to be limited. The soils in their natural state will probably be above optimum moisture for ade- quate compaction. In order to use these soils, drying will be necessary. Unly clean granular soil will be used for fill behind retaining structures. While careful segregation of the natural soils during excavation may provide some suitable backfill, it is anticipated that much of the backfill behind the walls and for any areas of structural fill will have to be imported. Stockpiling will be limited as much as practical on the site to minimize potential impacts on slope stability and erosion. If stockpiles are required, they should be placed at the north end of the site. The size and height of the stockpiles should be determined on a site - specific basis as construction progresses and in coordination with the geotechnical engineer. The geotechnical engineer recommends that temporary cut slopes be made no steeper than approximately 1i:1 (horizontal to vertical) and be limited to 15 feet in height. The stability of these temporary cut slopes will be relati- vely low. Analyses indicate that the factor of safety under static, drained conditions will be on the order of 1.2 to 1.3, assuming some short -term cohe- sion. Some sloughing or localized sliding should be anticipated, par- ticularly where zones of seepage are encountered. As recommended by geotechnical consultants, all permanent cuts and fills steeper than 3:1 (horizontal to vertical) or (33 percent) will be supported by retaining walls. Mitigating Measures All recommendations contained within the geotechnical report (Appendix A) will be complied with by the project sponsor. Mitigating measures and recom- mendations include, but are not limited to those summarized below: 1. Normal monitoring and maintenance of the existing deep drainage facilities on the 1 -5 right -of -way shall be performed by the Washington State Department of Transportation (WSDOT). The Department of Transportation is also responsible for replacement of drainage systems that are inoperative or worn out within their right -of -way. WSDOT has not been maintaining the vertical wells per se, but they are flushing the horizontal drains that tap into the vertical wells. Based on existing data, it appears that the majority of the vertical wells and /or horizontal drains are blocked to some degree. The existing drainage systems are considered critical to maintaining deep- seated slope stability above the adjacent roadways. The existing WSDOT drainage system is assessed by the geotechnical consultants as still effective in maintaining .water levels low enough for adequate deep- seated slope stability on the project site. 58 2. As a condition of grading and building permit issuance, the City of Tukwila could r'equir'e that formal agreements be reached between the deve- loper and the State of Washington regarding long -term commitments for ade- quate monitoring, maintenance and implementation of any remedial measures necessary to maintain the stability of both the project site and the WSDOT right -of -way. These detailed agreements should list each parties' respon- sibility for monitoring and maintenance of the various facilities and shall include contingency plans for implementation of any required reme- dial measures. 3. Slope movement and ground -water levels shall be monitored by means of an instrumentation program which will be maintained throughout the construc- tion phase and during the entire life of the project. A detailed action plan shall be prepared and promptly implemented in the event of signifi- cant changes in water levels or indications of slope movement. The geotechnical consultants shall be retained for the life of the project to provide or direct long -term monitoring and data interpretation, evaluate the performance of the hillside and recommend what, if any, remedial measures may be appropriate. 4. As a condition of building permit issuance, the developer and project owners could be required to post three bonds. One bond would make funds available to restore the existing environment and stability of the hillside in the event that, during construction, the project is determined by the developer to be infeasible for any reason. The second bond would make funds available to adjacent property owners to compensate for damages caused directly from any earth movement on the site at any time during the life of the proposed development. The third bond would make funds available, as required, to ensure that the geotechnical consultant is retained to provide or direct the slope instrumentation /monitoring program during the life of the project and for implementation of any remedial measures required to maintain the stability of the project area. Such bonds, however, may not be available in the market or may be so costly that the proposed development may be rendered infeasible. 5. The contractor shall comply with the geotechnical engineer's general sequence for site development. Site grading shall be undertaken during the late summer - early fall months when the least amounts of rainfall can be expected and surface runoff and seepage from springs should be somewhat diminished. 6. Individual structure grading shall be performed on an alternating basis, with the number of sites prepared limited to the number for which foun- dation, retaining wall construction and backfilling can be completed during the dry season. Construction shall be scheduled so that site grading, drainage installation, and surface stabilization are completed in any given area within a single construction season. 7. All permanent cuts steeper than 3:1 horizontal to vertical (33 percent) shall be supported by retaining structures constructed and backfilled per the specifications of the geotechnical report. 59 8. Except for localized areas near the existing gully, general fill placed on the site shall not extend above the original ground surface. Temporary stockpiles, if any, shall be placed at the north end of the site and shall be limited to minimize potential impacts on slope stability and erosion. 9. The existing 12 -inch sewer line will be realigned so as not to be located below any building structures. 10. Building foundations, retaining walls, and associated drains shall be constructed per the specifications of the geotechnical report. 11. See related Mitigating Measures listed under "Geology and Soils ", "Surface Water Movement, Quantity, Quality, Runoff /Absorption ", and "Groundwater Movement, Quantity, Quality ". Unavoidable Adverse Impacts While the recommendations for earthwork, site drainage and erosion control structures for the project are intended to increase surficial slope stabi- lity, there is always the possibility that localized conditions may vary to the extent that some earth movements might occur during construction. These are anticipated to be small in nature and are not expected to result in any earth spillage outside of the site limits. Topography Existing Conditions The site slopes toward the east and northeast with the majority of the site with slopes in excess of 20 %. A large drainage swale transects the southern portion of the site, resulting in the sewer alignment curving to the west around this swale before swinging to the northeast. There are three benches on the site that appear to be manmade. The presence of the benches may be indicative of remedial grading following previous slide activity. The lowest bench appears to have been constructed during the installation of the sani- tary sewer line and essentially follows the sewer alignment to a point where the sewer line crosses the property line at the center of the eastern pro- perty line. The ground surface downslope from the sewer bench in the southeast corner of the site is moderately steep. A second bench starts at the southern property line slightly upslope from the sewer line bench and is oriented approximately parallel to the sewer line bench for approximately one -third the length of the site at which point it disappears. The third bench is located in the center of the site and may have been constructed during installation of an old surface drain in this area. Slopes at the site are generally on the order of 20 to 30 percent, steepening in places to over 40 percent. See Figure 6, Slope Analysis. Also refer to discussion of Natural Environment under City of Tukwila Comprehensive Policy Plan, Objective 3, Policy 1, in Chapter II of this EIS. 60 Impacts The topography of this site will be altered in order to develop the grades necessary for roadways, parking area and building construction. Topographic alterations will include cutting, minor amounts of filling, and the installa- tion of retaining walls as necessary to control the maximum slopes to which the ground surface is graded. Except for localized areas near the existing gully, general fill placed on the site shall not extend above the original ground surface. As recommended by the geotechnical consultant, permanent cut and fill slopes shall be established at no steeper than 33 percent (3:1), or shall be supported by retaining walls. Temporary unsupported cut slopes shall be no steeper than 66 percent (1.5:1) and shall be limited to 15 feet in height. A discussion of slope stability as a function of both slope and subsurface soil conditions is presented in the "Geology /Soils" section. Mitigating Measures Please refer to mitigating measures listed under "Geology /Soils ". Unavoidable Adverse Impacts Site alterations during portions of the construction phase may result in tem- porary slopes somewhat steeper than the final configuration that will be achieved. Grading for preparing the site for construction will permanently alter slopes and features (i.e. drainage swales) on the site. Erosion Existing Conditions Flow from spring activity on the moderately steep slopes, as well as from horizontal drains that still exist on the site, has led to the development of several erosion gullies on the site. Dense vegetation assists in minimizing surface erosion on the majority of the site. Evidence of previous slope instability is discussed under "Geology /Soils ". Impacts Erosion will increase during the construction stages due to the removal of soil stabilizing vegetation and the disturbance of surficial soils. The greatest potential for erosion will be on the steeper slopes. particularly during periods of precipitation and where zones of seepage are encountered. Mitigating Measures 1. City of Tukwila requirements for grading and excavation will be followed to minimize or avoid erosion. 2. Plastic sheets and mulch will be used on portions of the exposed soil areas during construction to minimize erosion. 61 3. Landscaping shall be installed as soon as possible subsequent to comple- tion of construction and shall include plants suitable for the stabiliza- tion of the surface of steep slopes. 4. Collection of all onsite seepage and springs will be done prior to and during construction to minimize surface flow that could cause erosion. Existing onsite horizontal drains will be' located and connected to the site drainage facilities. 5. Temporary drainage ditches will be installed to collect runoff immediately following site clearing and grubbing. 6. Temporary storm management and erosion control measures will be utilized during construction. Where possible, natural vegetation for silt control shall be maintained. Proposed interim drainage and erosion control measures include placing straw bales in drainage ditches and swales, directing runoff toward temporary siltation ponds, seeding and placing jute matting. 7. All temporary siltation ponds and other drainage and'erosion control measures shall be maintained in a satisfactory condition until such time as clearing and /or construction is completed and permanent drainage faci- lities are operational. 8. See related Mitigating Measures listed under "Geology and Soils ", and "Surface Water Movement, Quantity, Quality, Runoff - Absorption ". Unavoidable Adverse Impacts Stripping of site vegetation will create the possibility of surface erosion due to rainfall and seepage from springs; any potential of off -site impacts will be controlled by implementation of a City- approved temporary erosion and sedimentation control system. Air Air Quality Existing Conditions Particulates: No monitoring of air quality has occurred in the site vicinity in several years, nor has any monitoring been performed in connection with this proposal. The following discussion of existing conditions reflects the most recent data available from the closest monitoring stations to the site. The Washington State Department of Ecology (DUE) has been designated as the responsible agency to obtain statewide air quality monitoring data needed to determine the status of compliance with the National Ambient Air Quality Standards. DUE's monitoring sites are located where the worst air quality conditions are expected to exist. Particulates, more commonly referred to as "dust ", are minute particles of matter suspended in the atmosphere. They represent the visible component of air pollution that locally is often seen as a "haze" during periods of air 62 stagnation and may be toxic or irritating to lung tissue. Prevailing winds can play a role in distributing particulates, from high concentration areas in central Seattle and Tacoma to the general vicinity within which the project site is located. Data accumulated by the Puget Sound Air Pollution Control Agency (PSAPCA) indicates that the concentration of suspended particulates in the Tukwila area has generally i ncrea'sed '.with increased urbanization of the Valley. The following table summarizes particulate data collected at an air moni- toring station in the Southcenter vicinity from 1975 -1981: TABLE I Summary of Suspended Particulate Concentrations Tukwila Area Annual Geometric Mean micrograms per cubic meter WN. State Location 1981 1980 1979 1978 1977 1976 1975 Std. Southcenter 47 48 50 46 48 45 34 60 (Source: Puget Sound Air Pollution Control Agency, Air Quality Data Summary -- 1977, 1978, 1979, 1980 and 1981.) The table indicates the particulate levels during the period monitored did not exceed the Washington State Ambient Air Quality Standards. Based on the proximity of the site to the monitoring station, it is expected that the air quality conditions at the project site were simi- lar to the recorded levels. Automobile Generated Pollutants: Carbon Monoxide, hydrocarbons and nitrogen oxides are pollutants generated by automobile emissions. Carbon Monoxide (CO), which accumulates in areas of heavy slowly moving traffic, can reduce the oxygen carrying capacity of blood, resulting in drowsiness and loss of vigor. CO levels vary more by location than do particulates and therefore, it is difficult to accurately estimate levels at unmonitored sites. Hydrocarbons and nitrogen oxides react over time in the presence of sunlight to produce ozone. Ozone aggravates the conditions associated with asthma, heart and chronic lung disease. Ozone concentrations are highest near major urban areas. 63 Table Ii provides measurements of these automobile - generated pollutants as taken at a monitoring station near the site by the State Department of Transportation. iNo monitoring has been done in the site vicinity since 1977. TABLE II Summary of Automobile Generated Pollutant Levels General Vicinity of Project Site (in PPM) Hydro Nitrogen Period Carbon Monoxide Carbons' Dioxide (mo.,yr.) .1 Hour 8 Hour -6 1 AM Study Period Location Max. Max. Avg. Avg. Puget Power 6/7 , 1977 3.2 2.0 0.37 0.02 Transformer Yd 3/4 , 1977 4.2 3.3 0.28 (Renton) 10 /11, 1976 .8.1 6.6 0.01 6/7 , 1976 2.2 1.3 0.04 State Ambient 35.0 9.0 0.05/ Air Quality Annual Standard Average (Source: Washington State Department of Transportation 1977 Monitoring) 1State Ambient air quality standard for hydrocarbons is no longer in effect. As reflected by Table II, when last measured, none of the pollutants levels near the project site exceeded applicable State standards. Sulfur Dioxide: Sulfur Dioxide (SO2) pollution is produced through the burning of fossil fuels and is associated with a variety of respiratory ailments. The nearest station which monitored sulfur dioxide was located at the Duwamish Pump Station, 4500 East Marginal Way, Seattle, approximately eight miles from the site. The sulfur dioxide levels measured did not exceed Washington State standards. According to Stuart Clark of the Department of Ecology, sulfur dioxide levels in Tukwila should be equal to or better than those recorded at the Duwamish Pump Station. Typically, sulfur dioxide levels are high near pulp mills or smelters. Automobiles emit very little sulfur dioxide and are not considered as a source of this pollutant by the Department of Ecology. Impacts During site clearing and grading and other construction activities, par- ticulates or "dust" will be generated, as will emissions from construction vehicles. Some long -term increases in motor vehicle - generated pollutants (e.g. CO and hydrocarbons) and particulates will result from project traffic, 64 Unavoidable Adverse Environmental Impacts Short -term noxious odors will be produced during construction. Climate Existing Conditions The site is located in the Green River valley and has a typical Northwest Pacific Coast marine climate. During the fall and winter, prevailing winds are from the south and southwest, and during the late spring and summer from the north and northwest. Low level temperature inversions may occur in the valley which, coupled with low wind speed, can result in the trapping of pollutants. This condition is most prevalent during the winter months. Impacts None. Mitigating Measures None. Unavoidable Adverse Impacts None.. Water Surface Water Movement, Quantity, Quality, Runoff /Absorption Existing Conditions The site is currently devoid of developed impervious surfaces. The site slo- pes generally from west to east with a large drainage swale bisecting the southern portion of the site. Evidence of surface runoff during periods of precipitation is evident from the several erosional gullies observed at the site. The onsite drainage basin is bounded by Slade Way on the south and the exten- sion of South 158th Street on the north. The onsite drainage basin is 7.2 acres in area and is divided into two sub - basins. The south sub -basin is 4.4 acres in area while the north sub -basin is 2.8 acres in area. Off -site flow from approximately 12 acres west of Slade Way and south of South 160th Street is intercepted and transported downslope through the pro- ject site via an existing storm .sewer shown on the site utility plan on Figure 16. Part of the system, a 15 -inch storm sewer parallel to 53rd Avenue South, runs above ground and is leaking (observation 10/17/83), resulting in some local ponding and an increased flow of surface water and near-surface seepage in the adjacent portion of the project site. The system also con- sists of 12 -inch and 18 -inch underground drain pipe and runs generally in a 66 north -south direction. This pipe connects to a 24 -inch line described in the following paragraphs. Drainage from the project site flows to the Green River through a series of pipes and open channels which are described below. Surface runoff from the southern portion of the site (4.4 acres) sheet flows to a rip -rap lined ditch which bisects the south side of the site. This ditch flows to a receiving structure on the south side of Klickitat Drive. A 24 -inch pipe runs from the receiving structure to a manhole where the pipe size increases to 30- inches under Klickitat Drive. This 30 -inch line then runs parallel to Klickitat Drive and connects to a 48 -inch line that runs parallel to the northbound lane of Interstate 5. The 48 -inch line then crosses under Interstate 5 and discharges into a lined open channel which is on the west and north side of Southcenter Parkway. The channel flows through a short section of 78 -inch pipe and a section of 108 -inch pipe and then discharges into the Green River. Surface runoff from the north portion of the site (2.8 acres) sheet flows to a lined ditch along the east side of the site. The ditch flows to a receiving structure near the northeast corner of the site. An 18 -inch pipe runs from the structure to a manhole where the pipe size increases to 24- inches. This line runs under Interstate 5 and ties into the same 48 -inch line described in the preceding paragraph. The flows follow the same route to the Green River as described for the southern portion of the site. The WSDUT gravity flow drainage system of large diameter vertical wells con- nected to horizontal drains also discharge flow to the systems described above. Several seeps or springs have been observed on the site, some of which may be originating from old horizontal drains. The other seeps may be natural or may also be originating from covered horizontal drains. The extent of seep and spring activity is expected to vary seasonally with higher levels of seepage occuring during the late winter and spring season. Many of these seeps were observed on the upper portion of the site outside of the area of planned development. Seeps or springs within the project area can best be located at the time site work is done so that flow from them can be collected and directed into the drainage system in an effective manner. Surficial stability of the site is largely affected by surface runoff and near-surface seepage through the upper soil (Unit A) which mantles the pro- ject site and adjacent properties. As stated in the geotechnical report pre- sented in Appendix A, permeability of the soil is relatively low in Units A and B, and is significantly higher in Unit C. There is no known water quality data available for surface runoff from the site. 67 Impacts Existing surface runoff and absorption characteristics would be altered by the following aspects of the proposed development: installation of drainage systems; removal of vegetation during site preparation; grading, excavation and filling during construction; and introduction of impervious surfaces on the site in form of roads, parking areas and structures. Absorption would be reduced, and the rate and volume of runoff would be increased. Runoff pat- terns will be altered to the extent that slopes are changed and retaining walls installed. Drainage facilities will be installed to collect runoff and seepage, both above and within the area of development. This flow will be directed to the stormwater drainage system. Offsite features such as the City of Seattle 60 -inch water main are not expected to be adversely affected by the proposed development. Construction of the proposed development would not alter existing drainage basin boundaries. Site development would eliminate existing natural surface flow and infiltration characteristics and introduce additional buried conduit systems. The new drainage collection system would contain and direct surface water at higher velocities and in different directions across the site, as shown on the Site Utility Plan. Stormwater would continue to exit the pro- perty at the same points along the southern and eastern boundary. No definite decision has been made regarding the type of surface runoff discharge facilities that will be incorporated into the project. City of Tukwila regulations require drainage retention and runoff control facilities designed to handle a storm of 10 year frequency. The proponent is con- sidering direct discharge of project site runoff into the storm drainage system for conveyance to the Green River. If a stormwater retention system is selected, surface water would be collected in a subsurface conduit system as shown on the site utility plan, which would direct stormwater drainage at higher velocities and in slightly different directions across the site. The new storm system would also collect existing on -site horizontal drains and footing and retaining wall drains. This proposed drainage system includes storm drainage retention pipes and control structures which would control and store storm water to limit the runoff rate to a predevelopment rate. Therefore, surface water would exit the site at approximately the same rate as it does under existing conditions. The installation of a storm drain system would provide positive benefits because it would collect and channel surface water, some of which is currently flowing in ill- defined channels, and direct it to a controlled system outflow. The storm drain system and the system of foundation and retaining wall drains will also increase the factor of safety against sliding in the upper layers of soil and provide less impact on the WSDOT drainage system. The 7.2 acre drainage basin is divided into 2 sub - basins, the south being 4.4 acres and the north 2.8 acres. Based on a storm of 10 year recurrence inter- val, the south basin would require approximately 1,500 cu. ft. of storage capacity, and the north basin would require approximately 1,000 cu. ft. of storage. The size of the controlled outlet from the site would be runoff at a rate that would not exceed existing conditions. 68 Since runoff from the site flows to the Green River as detailed in the pre - ceaing paragraphs, an alternate design would be to provide no detention for the site. There would be several benefits from direct discharge of storm- water. The principal benefit would be elimination of a possible source of water leakage from the detention structure. It would also eliminate some of the excavation and disturbance of the hillside on -site. The introduction of impervious surfaces would increase the peak surface runoff from a total of 1.36 cubic feet per second (CFS) to approximately 3.34 CFS during 10 -year storm conditions. This is an increase of 9.98 CFS at the peak. Surface runoff would increase a total of 1.67 CFS to 4.13 CFS during a 25 -year storm. This is an increase of 2.46 CFS at the peak runoff. This is a relatively small increase given the size and capacity of the downstream storm system which is capable of handling 20 CFS or greater. During storms of greater intensity, however, downstream drainage facilities could contain flows in excess of design cpapcity, resulting in localized flooding in the lowlands between the site and Green River. Unregulated discharge from the site (no on site retention) could have a cumulative impact on storm runoff peaks. The introduction of impervious surfaces over a portion of the proposed deve- lopment would reduce the area of exposed soils. Therefore, reduced quan- tities of sediment, nutrients and organic material contained in the soil would be expected to leave the site in surface runoff. However, in place of these would be a level of contaminants more typical of residential develop- ments: petroleum residues, traces of heavy metals, and sediments washed from roads and driveways. The increased quantity of impervious surfaces would increase the volume of stormwater runoff from the site. Catch basins and oil /water separators proposed within the on -site drainage collection system would function to separate sediments and petroleum residues from stormwater to a certain extent. Use of on -site drainage detention and outlet control structures would further allow for separation of these pollutants from storm water before release from the site. Use of pesticides, herbicides and fertilizers (if any) on yards or landscaping in common areas may occasionally contribute slight quantities of contaminants to stormwater that would not be removed by the proposed pollu- tion separation devices. Also, the partial coverage of soils with asphalt paving and structures may result in slight elevation of temperature of runoff from these surfaces. Construction procedures, especially excavation, will result in temporary increased levels of suspended sediments within the stormwater runoff. Clearing and grading would expose soils on the site to potential erosion by rainfall. Mitigating Measures 1. A stormwater system designed in accordance with City of Tukwila require- ments and the recommendations and requirements detailed in the geotech- nical engineers report could be installed. The City of Tukwila must approve stormwater drainage plans prior to the issuance of the building permit. 69 2. If a stormwater detention system is selected, it will be designed for a 10 -year storm and be capable of detaining •2,480 cubic feet of water. Stormwater would be stored in underground storage pipes. The detention system would also have an emergency overflow. The proposed stormwater collection and detention system would reduce the potential for adverse off -site impacts from runoff by controlling the rate of release to that which occurs under existing conditions. The length of time over which peak discharge would occur would be prolonged. 3. If direct discharge of stormwater is incorporated into the drainage plans, storm water would flow to the Green River through a series of downslope pipes and open channels. This would eliminate the potential for leakage from the detention structures and reduce the level of excavation and disturbance of the hillside. Upgrading of offsite drainage facilities would be provided where required to prevent adverse effects on these faci- lities. During intense storms, however, lack of on -site stormwater reten- tion could contribute to higher peak flows in off -site drainage facilities downstream of the site. 4. The site development sequence and facilities as presented in the geotech- nical report would be included in the detailed site grading plan. 5. All required temporary sedimentation and control facilities will be constructed and in operation prior to site earthwork, building construc- tion and paving. 6. Catch basins and oil /water separators are proposed within the on -site drainage collection system to separate sediments and petroleum residues from stormwater. On -site detention and the outlet control structure would further allow for separation of these pollutants from stormwater before release from the site. 7. Site drainage systems will be designed to minimize the opportunity for ground water recharge, including lining surface drains to prevent infiltration and constructing subsurface drains to minimize the potential for leakage or breaks. 8. Prior to site clearing, an interceptor trench will be installed at the toe of the roadway fill along the western boundary of the site as recommended in the geotechnical report and as shown on the site utility plan. 9. Temporary drainage ditches will be installed to collect runoff immediately following site clearing and grubbing. 10. A portion of the existing perforated storm system (D -3 drain) will be abandoned and replaced by the contractor /developer with a new storm line to handle off -site runoff as shown on the site utility plan. The existing storm line that is above ground and leaking will be repaired. The Washington State Department of Transportation will review and approve plans for such improvements. 70 11. Existing on -site horizontal drains shall be located and flows shall be collected and directed into the site drainage control systems. 12. Permanent French drains will be installed along the upslope sides of all parking areas, in the west trenching gully that crosses the site, and in any wet areas along the west side of the building units. 13. Foundation and retaining wall drains will be installed and connected to drainage systems along the east property line so the flow can be properly disposed of off the site. 14. Temporary storm management and erosion control measures will be utilized during construction. Where possible, natural vegetation for silt control shall be maintained. Proposed interim drainage and erosion control measures include placing straw bales in drainage ditches and swales, directing runoff toward the temporary siltation ponds, seeding and placing jute matting. 15. All temporary siltation ponds and other drainage and erosion control measures shall be maintained in a satisfactory condition until such time as cleaning and /or construction is completed and permanent drainage faci- lities are operational. 16. The contractor /developer will have maintenance responsibility for the drainage control facilities during construction. The homeowner's associ- tion will be required to assume long -term maintenance responsibility for these facilities after completion of the development. Catch basins and oil /water separators should be cleaned frequently and properly maintained to assure maximum attainable pollution separation. 17. Cleaning of streets and parking areas shall be undertaken whenever necessary during construction by the contractor /developer. 18. See related Mitigating Measures listed in the "Geology and Soils," section and "Groundwater Movement, Quantity, Quality," section regarding cleaning, flushing and regular maintenance of existing WSDOT drainage facilities. Unavoidable Adverse Impacts None. Groundwater Groundwater Movement, Quantity, Quality Existing Conditions Two separate and independent hydrologic regimes exist at the site. The upper regime, existing within soil Units A and B, is influenced by surface water runoff, seepage from upslope, and direct precipitation. Seepage volumes are small due to the relatively low permeability of these soils. Water pressures in this regime are likely to be hydrostatic. In contrast, the lower regime existing within Unit C is influenced primarily by subsurface groundwater 71 flow. The source of water is not precisely known; however, it is likely that it is upslope and to the west or southwest of the site. Water pressures in this regime were artesian at the time of the 1960 -61 slide. The permeability of the soil in the lower regime (Unit C) is significantly higher than the soils in the upper regime and seepage volumes would be expected to be correspondingly higher. The original water table at the site has been modified on three occasions in the past 25 years. The first modification occurred after the 1960 -61 slide when several onsite horizontal drains were installed in 1961 on the slope (see Figure 3 in Appendix A to the EIS). These were installed to alleviate the artesian pressures in Unit C groundwater levels above the ground surface. The second modification of the water table at the site occurred in 1966 when the Washington State Department of Transportation installed a series of large - diameter wells (see Figure 2 in Appendix A to the EIS). These wells were then pumped during construction of a cylinder pile wall along Klickitat Drive to the east of the project site. The third and most recent modification of the groundwater regime occurred near the end of construction of the cylinder pile wall, when horizontal drains were drilled to intercept the vertical wells and the pumps in the wells were subsequently switched off. Water levels in the two ground water regimes were measured using the piezome- ters installed in the borings completed in October 1983, three of the piezo- meters installed by Shannon & Wilson in 1966, and the WSDOT vertical wells. Piezometers in the recent borings are installed in Unit C, the lower ground water regime, with the exception of the second piezometer in Boring J which was installed in Unit B, the upper ground water regime. The piezometer levels in the borings were originally measured on November 18, 1983, and sub- sequently measured on three occasions between November 30, 1984, and March 12, 1985. These data are presented in Table B -1 in Appendix A to the EIS. Several readings of the Shannon & Wilson piezometers and the WSDOT wells were also obtained. These data are presented in Table B -2 and B -3 in Appendix A to the EIS. The piezometric data collected from November 1984 to October 1985 indicate relatively stable water levels in the lower ground water regime (Unit C) at the site. Water level depths during this period ranged from 29 to 77 feet below the ground surface at the site and 26 to 55 feet as measured in the Shannon & Wilson piezometers east of the site. The water level data from the WSDOT wells is less consistent and it appears that several wells or horizon- tal drains are plugged to some extent. In the upper ground water regime (Units A and 8), the water levels are expected to be variable, ranging from the ground surface to depths of 10 or more feet, depending largely on local topography, seasonal rainfall, and other factors. The locations of the piezometers for which data are available during the period December 1966 to June 1968 are shown in Figure 2 of Appendix A to the EIS. These piezometric elevations before and after drain installation, as 72 well as the 1985 readings, indicate that, with the exception of Piezorneter 232, the piezometric surface was lowered between 15 and 65 feet approximately three years after installation of the I -5 drainage systems. Since that time (June 1968) to the present, the water levels in the three Shannon & Wilson piezometers which were located indicate a rise of about three, 11 and 29 feet in Piezometers 1A, 1B, and 1, respectively. This indicates some degree of degradation in the drain system. A similar comparison was made of the water levels in Borings DM -1 and DM -3 from a June 1961 Dames & Moore report and. Borings D and G completed for this project and located just inside the east property line of the site. This comparison is based on water levels at the time of the slide and on March 1985. Borings DM -1 and DM -3 both indicated artesian conditions shortly after boring completion. Borings D and G indicate water levels approximately 56 and 77 feet below the surface, which represents a substantial reduction in water level in this area. A comparison was also made between the existing water levels in the large diameter vertical wells and the elevations at which the horizontal drains intersect the wells. If the system is operating at maximum effectiveness, the water levels in the wells should be about one to two feet higher than the intercept elevations (to account for head loss in the horizontal drain). Comparison of the data in Tables B -3 and B -4 in Appendix A to the EIS indica- tes that only a few wells (19, 22, 23, and 24) are operating effectively. The water levels in the other wells are generally on the order of 20 feet higher, and Wells 1, 2, and 3 up to 70 feet higher than the levels of the horizontal drains at the wells. The excess head in the wells appears to indicate varying degrees of clogging of the drains (increased head required to obtain flow) and reduced flow by alternate drainage paths. It appears that, with the exception of the four wells noted, all of the horizontal drains and /or vertical wells are blocked to some degree. It is likely that complete maintenance of the drain systems will affect the water levels in the wells and thus influence the conclusions to be drawn from the existing available data. However, in spite of the indicated reduced per- formance of the WSDOT drain system, the water levels at the site are still significantly below the levels that existed at the time of the 1960 -1961 slide and the system is, in the opinion of the geotechnical engineers, still effective in maintaining the water level in Unit C low enough for adequate (F.S. 1.6) deep- seated stability of the hillside. The operational life of WSDOT's horizontal drains is not well known. Depending on the soil type into which the drain is installed, the installa- tion method and other factors, drains may operate satisfactorily for many years. However, drains are also known to silt up or clog due to corrosion or algae and bacterial growths within the slotted sections of pipe. This can result in major, if not total, loss of operating effectiveness after a few years. There appear to be only limited WSDOT data available to assess periodic changes in performance of the WSDOT drain systems over the last few years due to sporatic maintenance and limited documentation. However, there are records of the water levels during the period December 1966 to June 1968 for several piezometers located immediately east of the site. There are also 73 records of the geotechnical consultant's piezometers from November 1983 through the present, and recent records of the water levels in three Shannon & Wilson piezometers and in the WSDOT wells (see Tables B -1 through B -3). The multiple well groups and horizontal drains provide a redundancy to the WSDOT drainage system. Some of the flow appears to have found other paths, possibly along the outsides of some horizontal drains, as evidenced by the flow through the panels at the retaining wall along Klickitat Drive. If no maintenance is performed, the drain system will continue to deteriorate, pro- bably accelerating with time. If the drains are flushed and the wells cleaned and redeveloped as necessary, the WSDOT system should continue to be effec- tive for many years. As discussed in the section entitled "Water ", several seeps or springs have been observed at the site. It is possible that some of the seeps may repre- sent flow from horizontal drains which were installed in 1961 to aid in sta- bilizing the hillside. These drains extend into the deeper aquifer, whereas the natural seeps are related to near - surface ground water movements. Ground water quality has not been measured at the site. Impacts The geotechnical consultants anticipate no impact on the WSDOT drain system from the proposed development if surface runoff is collected and routed off - site and surface water infiltration is minimized as recommended. This conclusion is based on the fact that the WSDOT system services the lover aquifer and the barrier of lower permeability soils afforded by Unit B essen- tially precludes continuity between the upper and lower ground water regimes at the site. Direct surface runoff will increase and direct infiltration into the ground surface will decrease as a result of the introduction of proposed paved areas and structures. It could be expected that seasonal watering of lawn areas and landscaping may introduce more water into the surficial soils than that which normally infiltrates due to rainfall. However, the overall area available for such infiltration will be reduced by paving and buildings so that a reduction in infiltration will result. Since the primary ground water aquifer beneath the site is overlain by relatively impermeable silt units (see Appendix A), no significant amount of water is expected to reach the deeper aquifer. Much of the water which infiltrates into the surficial soil, particularly upslope from the buildings, is expected to be collected by the various subsurface drains. The general directions of ground water movements in both the upper and lower soil units are not expected to be altered. Control of the buildup of artesian pressure in the underlying sand and gravel stratum (referred to as Unit C in the geotechnical engineering report) is of prime importance in maintaining the deep - seated stability of the hillside area and is critical to the protection of the adjacent street and highway system. If the WSDOT drainage systems should deteriorate to the extent that artesian pressures can again increase beneath the hillside, the risk of deep - seated and extensive earth movement can be expected to significantly increase. 74 The deep - seated stability of the project site is primarily. dependent on the continued effective operation of the WSDOT drain system. "It is improbable, in the opinion of the geotechnical engineers, that the water levels at the site will rise to critical levels in a short period of time (i.e., in days or weeks) but, rather, over a period of months. With monitoring at regular intervals, changes in water levels can be detected and appropriate remedial measures can be implemented. Mitigating Measures 1. Normal monitoring and maintenance of the existing deep drainage facilities on the I -5 right -of -way shall be performed by the Washington State Department of Transportation (WSDOT). The Department of Transportation is also responsible for replacement of drainage systems that are inoperative or worn out within their right -of -way. WSDOT has not been maintaining the vertical wells per se, but they are flushing the horizontal drains that tap into the vertical wells. Based on existing data, it appears that the majority of the vertical wells and /or horizontal drains are blocked to some degree. The existing drainage systems are considered critical to maintaining deep- seated slope stability above the adjacent roadways. The existing WSDOT drainage system is assessed by the geotechnical consultants as still effective in maintaining water levels low enough for adequate deep- seated slope stability on the project site. 2. As a condition of grading and building permit issuance, the City of Tukwila could require that formal agreements be reached between the deve- loper and the State of Washington regarding long -term commitments for ade- quate monitoring, maintenance and implementation of any remedial measures necessary to maintain the stability of both the project site and the WSDOT right -of -way. These detailed agreements will list each parties' respon- sibility for monitoring and maintenance of the various facilities and shall include contingency plans for implementation of any required reme- dial measures. 3. Slope movement and ground -water levels shall be monitored by means of an instrumentation program which will be maintained throughout the construc- tion phase and during the entire life of the project. A detailed action plan shall be prepared and promptly implemented in the event of signifi- cant changes in water levels or indications of slope movement. The geotechnical consultants shall be retained to provide or direct long -term monitorings and data interpretation, evaluate the performance of the hillside and recommend what, if any, remedial measures may be appropriate. The detailed action plan should include trigger levels for the inclinome- ters and piezometers, and specific actions by responsible parties should be established. The geotechnical engineers recommend that an overall rise in water level of 10 feet in the lower aquifer (Unit C), as measured by any of the onsite piezometers, be taken as a "trigger" level for remedial action. Other trigger levels related to the WSDOT drain systems should be established once they have been cleaned out and are working more effec- tively. Trigger levels for the inclinometers should be based on an increase in displacement of more than 0.2 inches per year. 75 The action plan should consist of'the following: a. Notifying GeoEngineers, Inc., ''immediately. b. Analysis of the data by GeoEngineers, Inc., to establish the probable cause of the changed conditions at the site. c. Developing recommendations for obtaining additional information if necessary and to implement the necessary remedial measures. These recommendations may include, but . are not limited to: o Obtaining additional information such as surveying the settlement hubs at the site. o Increasing the monitoring frequency. o Maintenance or restoration of the on -site drainage or WSDOT drain systems. o Installation of new horizontal drains on or off site ( WSDOT right -of -way). o Pumping the vertical wells in the WSDOT drain system. o Implementing localized slope stabilization measures. 4. Given the importance of the WSDOT drain systems on the stability of both the project site and the adjacent roadway facilities, the geotech- nical engineers recommend that the following repair work and main- tenance procedures be implemented by WSDOT as soon as possible. o Clean out and flush the horizontal drains (cleanout lengths should be consistent with known drain lengths). o Clean out, flush and develop, if necessary, the 24,vertical wells. o Extract the pumps after flushing. (It is likely that the pumps are silted in and may not be able to be extracted without flushing.) o Sound the depths of the wells. o Secure the top plates on the wells to prevent extraneous matter from being thrown into the wells. o Repair the "original test drain" system. o Locate and document the manifold outlets for the original test drains. o Monitor the flows from both systems of horizontal drains and the piezometer levels in all wells and WSDOT installed piezometers.. 5. See related Mitigating Measures listed under "Geology /Soils ", regarding maintenance of existing drainage facilities. 76 6. See related Mitigating Measures listed under "Surface Water Movement, Quantity, Quality, Runoff /Absorption ", regarding surface drainage and storm water control facilities (which will contribute to absorption and infiltration). Unavoidable Adverse Impacts Increased importance of the monitoring, maintenance, and repair of all drainage facilities and slope instrumentation that may have a bearing on con- tinued deep - seated stability of the hillside for the life of the project. Flora Existing Conditions The site is covered with small diameter alder. According to the Soils Report, the alder in the middle and eastern portions of the site appear to have grown since the slide that occurred on the site between 1960 and 1961 (as a result of excavation of borrow material). Undergrowth includes dense blackberry and some horsetails. Impacts Approximately 68 percent of the existing vegetation would be removed from the site. Most existing vegetation along the eastern portion of the site would be cleared and replaced with buildings, parking and ornamental landscaping. These changes will permanently alter the vegetation of the site. The western portion of the site (2.3 acres) would remain in its natural state. To the extent possible vegetation will be returned in the area nearest the freeway. Mitigating Measures 1. Approximately 2.3 acres, or 32% of the site will remain in its natural state, including the southwestern portion of the site. Disturbed areas not proposed for landscaping will be treated for erosion control by seeding with clover and rye or ivy. 2. Urnamental vegetation will include sycamores along Slade Way and along the perimeter of the parking lot. Vine maple and flowering cherry will be interspersed among the buildings. Additional plant materials will include platinia, rhododendron, mahonia, viburnum Davidi, ivy and lawn (Figure 7). The proposed landscape plan is subject to approval by the Board of Architectural Review. Unavoidable Adverse Impacts All natural vegetation from approximately 68 percent of the site will be removed. 77 = L ■-• :tVf.V:\ TTi Lr-T. • L...., • • C0•01.'t • ■,- Fauna Existing Conditions Wildlife on the site consists of small birds, squirrels, rodents and possibly raccoons. No threatened or endangered species are known to inhabit the area. Impacts The clearing of the vegetation for buildings, parking lots and landscaping would result in a loss of approximately 68 percent of the existing habitat on site. Increased human activity will diminish the value of the remaining natural area. Species presently inhabiting the site would be displaced to other areas of the wooded hillside. Some would perish in competition for the remaining habitat. Different, urban tolerant species may appear over time. Mitigating Measures Approximately 2.3 acres or 32 percent of the site will remain in its natural state. Unavoidable Adverse Impacts Removal of vegetation will result in a slight loss of animal habitat and the displacement and /or elimination of most species that currently utilize the site. Noise Existing Conditions The project site, and adjoining properties, are exposed to significant noise levels due to their proximity to I -5. The extent to which noise poses a health hazard depends on its level, frequency and length of exposure. The range of health hazards associated with high noise levels are described in the Human Health section of this EIS. Existing day -night (Ldn) noise levels on the site are 65 -72 dBA, with maximum nighttime noise levels of about 77 dBA. (The day -night sound levels is an equivalent sound level over 24 hours with a 10 dBA penalty for nighttime noise. Definitions of other sound level descriptors may be found in Appendix B.) Day -night sound levels at the closest residential properties west of the site were found to be 63 to 65 dBA, with maximum nighttime levels of about 72 dBA. According to EPA's Noise Guidelines, significant adverse noise impacts (primarily speech interference and annoyance) occur at noise levels of 65 -75 Ldn. Noise levels in excess of 55 dBA can interfere with speech com- munication. Noise level measurements taken at the project site over a four - day period in October 1983 provide more detailed information about existing noise levels. It can be expected that these documented noise levels will increase somewhat over time with expected increases in traffic volumes on I -5. 79 \\ • N. @MN awl 13 ICI mem D• 111 1 1I t EIRIAP ,w ,�,1►ice ifittpli mai Km Eto•FA ;I i 1 n SCALE ,%; !' O 100 200 BY •400 600 1000 FEEL Existing Noise Measurement Locations TOWNE, RICHARDS & CHAUDIERE, INC. 80 FIGURE 8 Consultants in Sound & Vibration The noise measurements consisted of full 24 -hour noise monitoring at three locations and 19 hour noise monitoring at the fourth location, where adverse weather •curtailed the measurement. A Digital Acoustic DA607P noise moni- toring system was used for the measurements. Results of the measurements in hourly Leg, hourly Ldn are shown in Appendix B, Figures 2 and 3. Locations 1 and 2 are on the site. Locations 3 and 4 are off -site, near residence immediately west of the site which have views across the site toward I -5. The following is a summary of the measured day -night sound levels, Ldn, and nighttime maximum sound levels, Lmax: Table 3 Existing Noise Levels Location Description 1 2 3 4 SE part of site NE part of site Residence W of site Residence SW of site Existing exterior noise levels, dBA Ldn Night Lmax 72 77 65 (68 *) 77 65 72 63 72 *Location 2 had partial topographic shielding of highway noise, which is esti- mated to have reduced Ldn by about 3 dBA compared to noise levels at a future upper story elevation. The day -night sound level (Ldn) is the reading used in EPA in Guidelines for noise levels affecting residential areas. Those Guidelines are as follows: Ldn Below 55 dBA 55 to 65 dBA 65 to 70 dBA Table 4 EPA Noise Guidelines Levels are generally acceptable: no noise impact is generally associated with these levels Adverse noise impacts exist: lowest noise level possible should be strived for. Significant adverse noise impacts exist: allowable only in unusual cases where lower levels are clearly demonstrated not to be possible. Over 70 dBA Levels have unacceptable public health and welfare impacts 81 As a comparison of Tables 3 and 4 indicates, at two of the four sites where monitoring occurred, day -night sound levels exceeded EPA's threshold for significant adverse noise impacts. The other two sites were just below this threshold and at the high end of the range where adverse noise impacts can occur. Although EPA's evaluation of noise impacts is based on the day -night sound level and not on maximum noise levels, a review of maximum noise levels at the site over a 24 hour period (see Appendix B) indicates that maximum levels over 70 dBA are reached regularly. The noise level at the southern site location (Location 1) was found to have maximum levels exceeding 70 dBA during all 24 -hours tested and exceeding 80 dBA during the afternoon hours when people are apt to be outside. At the northern site location (Location 2) the maximum noise level was above 70 dBA during 10 of the 19 hours tested and above 80 dBA during six of these 19 hours. (Measurements were not taken from 1:00 p.m. to 5:00 p.m.) On the other two sites adjacent to the single family area to the west, noise levels measured above 70 dBA during 20 of the 24 hours tested at one site (location 3) and during 12 of the 24 hours tested at the other site (Location 4). Location 3 experiences maximum noise levels above 80 dBA during five hours (including the 5:00 p.m. - 7:00 p.m. period) while Location 4 experienced maximum levels above 80 dBA during the 6:00 p.m. hour. EPA sources specify that interior noise levels should have an Ldn of 45 dBA or less in order to protect health and welfare with an adequate margin of safety. Other studies indicate that to prevent the probability of sleep interference exceeding approximately 50 %, interior maximum sound levels, Lmax should be limited to about 50 dBA in bedrooms. A different set of standards is utilized by the U.S. Department of Housing and Urban Development (HUD) to determine site acceptability for HUD projects. HUD's criteria are as follows: Table 5 H. U. D. Acceptability Standards Ldn Site Acceptability Standard Not exceeding 65 dBA Acceptable Above 65 dBA but not exceeding 75 dBA Normally Unacceptable Above 75 dBA Unacceptable On sites where Ldn is above 65 dBA but does not exceed 70 dBA, HUD requires that the type of construction used reduce interior noise levels by 5 dBA beyond the 25 dBA reduction that is typically accomplished with standard construction (i.e., a total noise reduction of 30 dBA). A reduction of an additional 10 dBA (35 dBA total) is required for sites above 70 dBA which do not exceed 75 dBA. 82 Impacts Interior Noise Levels On -Site As indicated in Table 3, on the southeast part of the site (Location 1) the exterior day -night sound level (Ldn) was 72 dBA. On the northeast part of the site (Location 2) exterior Ldn was 65 dBA at a first story elevation and about 68 dBA at higher elevations. Nighttime maximum sound levels (Lmax) were 77 dBA at both locations. Since the exterior Ldn on the south half of the site is in the range of 70 -75 dBA and the Ldn on the north half of the site ranges from 65 to 70 dBA, the 25 dBA reduction attainable through conventional construction would result in noise levels inside the units of 45 -50 Ldn on the south portion of the site and 40 -45 Ldn on the north portion of the site. Thus, without special construction, noise levels on the south portion of the site would exceed EPA's recommended day -night level of 45 Ldn. Since maximum exterior night- time sound levels at both sites were 77 dBA, conventional construction would reduce the nighttime maximum to 52 dBA at both locations which is above the 50 dBA threshold beyond which a greater than 50% chance of sleep interference exists. Construction to meet the HUD standards described previously would require 10 dBA of additional attenuation on the south portion of the site (total reduc- tion of 35 dBA) and 5 dBA of additional attenuation on the northern portion of the site (total reduction of 30 dBA). A comparison of interior sound levels with and without added attentuation, and with open windows, is shown in the following table: Table 6 Interior Evening Noise Levels within Proposed Development Interior sound levels, dBA Ldn Night Lmax Construction 10 dBA added attenuation* 5 dBA added attenuation Conventional construction Open Windows 5 dBA added attenuation* Conventional Construction Open windows *HUD Standard Part of Site South 1/2 North 1/2 37 42 42 47 47 52 62 67 38 47 43 52 58 67 This comparison indicates that an exterior -to- interior noise reduction of 30 ddA (representing 5 dBA added attenuation) would provide generally acceptable interior noise levels on both portions of the site (interior Ldn below 45 dBA and interior nighttime Lmax below 50 dBA) when windows were closed, even 83 though the HUD standard of a 35 dBA reduction on the south portion of the site would not be achieved. However, maximum noise levels within units on the south portion of the site would periodically exceed levels at which adverse noise impacts occur: i.e., reach 55 dBA or greater. With windows open, interior noise levels would far exceed EPA's recornmended interior stan- dard of 45 dBA and in the discussion of Mitigating Measures, some form of forced -air ventilation would be necessary, especially in bedrooms, so that windows could be kept closed and noise levels maintained at acceptable levels. Exterior Noise Levels On -Site Exterior day -night sound levels (Ldn) on the site (i.e., 72 dBA on the southern part of the site and 65 to 68 dBA on the northern part of the site) are in a range above the 65 dBA where noise levels are considered to cause significant adverse effects according to EPA criteria. It should be noted that these levels reflect an average of 24 -hour day -night noise levels with a iO dBA penalty for nighttime noise. During many hours a day at both sites, maximum noise levels exceeded 75 dBA, with 80 dBA's occurring several hours a day. Thus varying degrees of speech interference and annoyance -- often reaching high or unacceptable thresholds -- would be experienced by project residents in unprotected outside areas. The noise consultant recornmended that noise mitigation for exterior spaces be considered, especially if the proposed children's play area is to be located on the northeast part of the site. Revisions to the site plan now propose to locate the children's play area in the southwest corner of the site where residential buildings should provide some reduction of freeway noise. Other potential mitigating measures are discussed in the Mitigation Measures section. New sources of noise resulting from occupancy of the development would include children playing and automobile traffic. However, according to the noise consultant, due to existing noise levels on -site, noise emanating from the residential development would be masked and is expected to be negligible. See Table 7, "Outdoor Evening Noise Levels On- Site." Noise Level Changes Off -Site Due to the residential nature of the proposed project, long term noise changes at off -site properties are expected to be negligible. The site currently has narrow -trunk alder growth which provides slight excess atte- nuation of I -5 freeway noise for properties west of the site. The trees were bare when monitored, and are estimated to provide at most 3 dBA of excess attenuation per 100 meters, or about 2 to 3 dBA excess attentuation for pro- perties west of the site. In summer, the excess attenuation would be slightly higher because of foliage. Construction of buildings on the site would provide partial shielding of views of the freeway, reducing freeway noise levels at properties to the 'west by about 3 dBA due to an approximate 50 percent shielding. This attenuation by the buildings would offset the loss of attenuation resulting from removal of existing trees on the site. According to the Noise Consultant, project traffic will have negligible impact on noise levels along local streets given the predominance of noise from the nearby freeways (I -5 and SR 518). 84 Day -night sound levels, Ldn, from street traffic were computed using esti- mated 1987 daily traffic volumes with and without the proposed project as described in the Traffic Impact Analysis. It was assumed that 10 percent of traffic occurs during nighttime hours of 10 p.m. to 7 a.m., and that traffic speed is about 30 mph. The noise prediction was for a setback of 50 feet from street traffic. Where appropriate, the street traffic noise was com- bined with noise from I -5. Table 7 1987 Day -Night Sound Levels, dBA Outdoor Evening Noise Levels on Site Sheet 53rd Ave. S. north of site S. 160th St. west of site Slade Way and 54th Ave. S. south of site Street Noise Combined Noise Freeway Noise without /with project without /with project 65 72 55/56 66/66 54/55 54/55 44/45 72/72 The largest noise increase, 1 dBA, would occur along S. 160th Street west of the site. This amount of noise increase would not be noticeable. Noise increases on other more distant, streets would also be negligible (less than 1 dBA increase). Construction Noise Temporary noise impacts would occur during construction of the project. Tnese impacts would be minimized by the fact that most construction would occur along the eastern part of the site, away from residences, and because existing freeway noise would mask much of the construction noise. The highest construction noise levels would be received at a residence at the corner of Slade Way and 54th Avenue S., about 100 feet from the southernmost proposed building. At this distance, construction noise levels could average between 59 and 82 dBA, depending on the activity and phase of construction, according to EPA data. Existing daytime noise levels from I -5 average about 7U dBA in this area. It is therefore expected that the noisiest activities could exceed the existing traffic noise by up to 12 dBA, but that the typical construction noise would be close to the levels of existing noise and there- fore would be largely masked. The closest residences west of the site would be about 200 feet or more from construction activity, and would receive estimated construction noise levels between 53 and 76 dBA, again depending on the activity and phase of construc- 85 tion. Typical construction noise levels would also be similar to the existing freeway noise levels (about 60 to 65 dBA) at these locations. During the early construction phase, the 3 dBA noise attenuation currently provided by trees on the site would have been lost by removal of trees during site clearing and would not yet be offset by the new buildings. Construction could not occur before 7 a.m. on weekdays and 9 a.m. on weekends, or after 10 p.m., because of State of Washington (WAC Chapter 173 -60) noise code restrictions on construction in residential areas during nighttime hours. Mitigating Measures Proposed Mitigating Measures (i.e., currently committed by the project sponsor): 1. The use of glass windows and doors with an acoustical performance at least 5 dBA better than conventional thermal insulated windows is proposed on north, south and east facing sides of the buildings to attain an exterior - to- interior noise reduction of 30 dBA throughout the project (5 dBA better than conventional construction). The windows will have a minimum overall outside thickness of one inch and will be set in resilient gaskets. Operable windows and exterior doors (including glass doors) will be hinged, rather than sliding, and will have resilient seals. In addition, exterior doors will have automatic threshold drops or compressible neoprene threshold seals. Detailed specifications for these windows and doors are described in Appendix B. This mitigation measure will bring interior noise levels to an Ldn of 38 on the north part of the site and 42 on the south part of the site, which is a generally acceptable interior Ldn based on EPA's Guidelines. Maximum noise levels at night would be reduced to 47 dBA at both locations which is less than the 50 dBA nighttime maximum threshold beyond which the pro- bability of sleep interference is over 50 percent. 2. Proposed construction materials will generally include double wall construction and one -half inch gypsum wallboards, R -11 fiberglass batt insulation, and double glazed aluminum windows. These materials will help attain the noise reductions referenced above but will not provide addi- tional attenuation beyond the proposed 30 dBA reduction. 3. The outdoor play area could be relocated north of the buildings in order to reduce play area noise levels by another 3 dBA (i.e., to 52 dBA). Proposed site plan revisions relocate the child's play area to the south- west portion of the site (see Figure 3). This layout uses the proposed residential buildings to separate the play area from the freeway, which would provide some attenuation of noise levels. The feasibility of this site for the play area will be reviewed when grading plans are submitted to determine if it is consistent with City standards for recreational facilities. 86 4. Construction will not occur before 7:00 a.m. on weekdays and 9:00 a.m. on weekends, or after 10:00 p.m., to prevent state noise code violations. In addition, any diesel or gasoline powered equipment used at the site will be required to have a proper muffler that is in good condition. Potential Mitigating Measures (not currently proposed by the applicant; possible conditions of building permit issuance). i. Forced -air ventilation could be required, especially in bedrooms, so that windows could be kept closed and noise levels maintained at acceptable levels. (With windows open, interior noise levels are 10 -15 dBA higher than when windows are closed.) 2. Additional exterior spaces, such as the proposed recreation areas, could be enclosed by noise barriers to reduce exterior Ldn below the level where EPA indicates that significant adverse noise impacts occur. The acoustic barriers could be constructed of wood with a minimum thickness of 3/4 inch. Plywood, or board and batten construction would be acoustically acceptable. The barriers should have no gaps or openings, including the base. Such barriers would have the disadvantage of blocking views from the site. 3. Noise levels on the outdoor decks could be reduced by about 5 dBA by using a solid barrier around the deck of the material described above. The barrier would need to be high enough to block views from the freeway from a typical user location (presumably seated), but would not need to be so high that it blocked views of the valley and mountains to the east. 4. East- facing decks could be glass - enclosed, to effectively provide double windows between the outside and inside of the residential units. If this construction were used, the one -inch thickness proposed for exterior win- dows would not be necessary for the exterior or interior windows of the deck area. i 5. Fencing around exterior recreation areas, particularly the children's play area could be used to achieve additional noise reductions. Noise levels could be reduced to an Ldn of 55 dBA or less, which is the minimum level for avoiding speech interference and annoyance outdoors. Unavoidable Adverse Impacts 1. With windows open, day -night noise levels inside the units would far exceed the standard EPA considers acceptable: i.e., levels would range from 58 -62 Ldn versus EPA's 45 Ldn standard. At night, maximum noise levels would far exceed the maximum noise level beyond which a 50% proba- bility of sleep interference occurs: i.e., 67 dBA max versus threshold of 50 dBA max. 2. With windows shut, day -night noise levels inside the units would be within EPA's recommended standard, but maximum noise levels in units on the south portion of the site would periodically reach levels at which adverse noise impacts occur (primarily speech interference and annoyance): i.e., 55 dBA or greater. 87 3. Without acoustic fencing, exterior noise levels including the proposed recreation areas, would have noise levels ranging from levels EPA charac- terizes as having significant adverse impacts (i.e., Ldn of 65 -70 dBA) to those EPA considers to have unacceptable public health and welfare impacts (i.e., Ldn of over 70 dBA). During the daytime, maximum noise levels within these areas would regularly exceed 75 dBA, occasionally reaching 85 dBA. 4. Construction noise at the closest adjacent residences could on occasion sharply exceed existing traffic noise by up to 12 dBA, although typical construction noise would be masked by noise from the freeway. 5. Following site grading and before project completion, properties to the west would experience a slight increase in freeway noise (i.e., 2 -3 dBA) due to the loss of trees. (Upon project completion, noise attenuation from the buildings would offset this slight increase in noise levels). Light and Glare Existing Conditions There currently are no sources of light or glare on the site. Impacts The proposed development would produce new light sources (i.e., parking lot and building lighting) that will be visible from the valley floor and the immediate vicinity. Parking lot lighting, including the entrance driveway, will largely be screened from the valley floor by the buildings and vegeta- tion on site. Headlights of vehicles entering and leaving the site will emit light at night, although light from this source should not impact existing residences to the south and southwest, again due to site vegetation. Interior building lighting will be visible through the windows at night, although light spill from residences should not be significant. Due to the distance between the valley floor and the site, glare resulting from reflec- tions from windows is not expected to be a problem. Given that the proposed floor elevations are 50 to 90 feet above the freeway with substantial vegeta- tion remaining between the freeway and site, light and glare from freeway traffic should have insignificant impacts on project residents. Mitigating Measures 1. Perimeter landscaping will reduce light spillage. 2. Parking lot lighting will be directed so that no direct light spills off the site. 3. Exterior light fixtures will be selected which do not project light above 20 feet in height. 88 Unavoidable Adverse Impacts None. Land Use Existing Conditions The 7.08 acre site is on the east - facing slope of an undeveloped hillside overlooking I -5 in the southwest quadrant of the I -5 /I -405 intersection. It is covered with a dense stand of second and third growth alder. The southern and western site boundaries are defined by Slade Way and 53rd Avenue South. Klickitat Drive lies between the site and I -5 to the east. The northern site boundary is just south of S. 158th Street, if extended. The surrounding area, i.e., south, west, and north of the site, is primarily occupied by single family detached homes at a density of three to five units per acre, with some property not yet developed. Several houses are located directly across 53rd Avenue South to the west, considerably above street grade. The nearest house to the south is located near the corner of Slade Way and 54th Avenue South. Single family plats comprising the McMicken Heights neighborhood extend further uphill to the west and to the south. Property abutting the site on the north is undeveloped. South 160th Street, which is designated as a residential street, would serve as a primary vehicular route from the site to local schools and recreation facilities and to Pacific Highway South and its associated commercial uses. Klickitat Drive via 53rd Avenue South provides access to I -5, 1-405 and the Southcenter Regional Mall. As described in the Traffic section of this EIS, local streets in the area are generally in fair to good condition with limited shoulders and no sidewalks. Impacts The proposed multi - family development would have an overall density of 15.25 dwelling units per acre compared to the three to five dwelling units per acre that characterizes the surrounding neighborhood. The proposed three - story, six -unit buildings would be the only multi - family structures in this part of Tukwila's planning area. They are potentially allowed because the applicant vested his rights prior to the effective date of the current Zoning Ordinance, which zoned the project site, like surrounding properties, for low density single - family use. Under the prior Zoning Code, three zoning classi- fications applied to the project site: R -1. R -4 and RMH. Approximately 32% of the site would remain in natural open space. Proposed buildings are pri- marily within the R -4 and RMH designated areas. Development planned for the R -1 designated area is limited to the children's play area, and parking and access facilities. Development of the site as proposed would create a legal, non - conforming use which would restrict owners' abilities to structurally alter the buildings. Under the non - conforming use provisions of the Zoning Code, owners would not be allowed to enlarge or alter the structure(s) in any way which was deter- mined to increase their degree of non - conformity. See Appendix C, Chapter 89 , • 1 • • ••-• Pin COMMERCIAL ErIJ. .PUBLFICA/SEMIl cILTyPUBLIC UNDEVELOPED LAND EXISTING LAND USE 18.70 of the Zoning Code relating to "Non- conforming Lots, Structures and Uses." Certain adverse economic impacts could affect owners of the proposed development due to its non - conforming legal status. For example, since a non - conforming use cannot be reconstructed if the cost is more than 50% of the total replacement cost, loan institutions might require collateral other than the residential property or an insurance policy to cover possible losses. While it is the City's intent to require that prospective purchasers be notified of the project's non - conforming status, such a requirement could be difficult for the City to enforce. There may also be adverse economic impacts related to the site's location on an area of potentially unstable slopes. Lending institutions might prefer collateral other than the residential units or separate insurance policies to protect their loans, particularly if the units are sold as condominiums. Rates for liability insurance may be higher than average residential rates. The requirement that the City of Tukwila, its officers, employees, and agents be indemnified from all claims, damages, losses, or liabilities arising directly or indirectly from any earth movement on the site could also contri- bute to higher insurance rates. As indicated above, the proposed structures would be substantially larger in scale and higher in density than surrounding residential uses. While the Traffic Report indicates that neighboring streets have adequate capacity to accommodate projected traffic volumes, a significant percent of project traf- fic would have destinations to the west and travel through the adjacent single family residential area. For example, one -third of the project's daily traffic (or 300 trips) would occur on S. 160th Street between 51st Avenue S. and 42nd Avenue S. As reflected in comments on the Draft EIS, many existing residents of the area believe the project will seriously diminish the quality and integrity of their single family neighborhood. Special concern has been expressed regarding pedestrian safety in the area given increased traffic volumes, limited roadway shoulders and the lack of sidewalks. (See revised Transportation section of this FEIS). There is also concern that the propo- sal would establish a precedent for additional multi - family development in this area. While no additional multi - family development is considered likely given the recent re- affirmation of single family zoning in this area and its low- density residential designation on the Comprehensive Plan Map, there is no guarantee that pressure for multi- family rezones would not develop over time. Consequently, the cumulative effects may cause a sense of loss in the quality of life of the residents in the vicinity of the development. Neighborhood cohesion may be adversely affected as a result of changes in local residents' perceptions toward the undeveloped land and low- density residential character of the area. View blockage has not been identified as a significant concern since the clo- sest houses to the west are sited at least 20 feet above the proposed roof peaks of the condominium buildings. The grade of the southernmost buildings would be nearly the same elevation as Slade Way. Neither is the project expected to have a significant effect on noise levels in the area due to the background noise attributable to I -5. 91 Development of the site would foreclose the possibility of the site remaining as open space and continuing to serve as a visual buffer between the I -5 corridor and properties uphill to the west. However, the site is not designated on the Comprehensive Plan as a greenbelt or as future park space. The relationship of this proposal to Comprehensive Plan goals, policies and objectives is analyzed in detail in the earlier discussion of the City of Tukwila Comprehensive Plan. Special construction techniques and other miti- gating measures that would be required in order to develop this project on potentially unstable slopes are discussed in detail in the Earth section of this FEIS. Mitigating Measures 1. The building will be sited along the east half of the property which pro- vides a 15 to 35 foot topographic separation from 53rd Avenue South. Existing houses west of the site are a minimum of 20 feet above the pro- posed project's roof peaks. 2. The site plan, provides a landscaped buffer along the western edge of the property partially screening the housing from commuters on Slade Way and 53rd Avenue South and from residences in the McMicken Heights vicinity. 3. As a condition of building permit issuance, the developer and project owners could be required to post three bonds. One bond could make funds available to restore the existing environment and stability of the hillside in the event that, during construction, the project is determined by the developer to be infeasible for any reason. The second bond could make funds available to adjacent property owners to compensate for damages caused directly from any earth movement on the site at any time during the life of the proposed development. The third bond could make funds available, as required, to ensure that GeoEngineers, Inc. is retained to provide or direct the slope instrumentation /monitoring program during the life of the project and for implementation of any remedial measures required to maintain the stability of the project area. As noted before, the uncertain availability of these bonds or their cost may render the development infeasible. 4. The City of Tukwila may require a covenant be signed and acknowledged by all owners before a person authorized to take acknowledgement of deeds so as to become part of the real estate property records. The covenant could include: (i) a statement that the owner will inform his /her successors and assigns that the property is in a potential slide area, of the risks associated with the development thereon, and of any conditions or prohibi- tions on development, and (ii) a statement waiving the right of the owner, his /her heirs, successors and assigns to assert any claim against the city by reason of or arising out of issuance of permits by the City for deve- lopment on the property, except for such losses that may directly result from the sole negligence of the City. 92 Unavoidable Adverse Impacts 1. An undeveloped wooded hillside would be converted to a multi- family housing development with associated parking areas and road surfaces. 2. The project's character, including density and scale, would differ substantially from that of the surrounding single family neighborhood. 3. Residents in the surrounding area would feel a loss in the quality and cohesion of their single - family neighborhood. 4. Project owners would be subject to the conditions of a legal non- conforming use. A requirement that proper notification be given to prospective purchasers regarding the project's non - conforming status might be difficult for the City to enforce. 5. Project owners might be required to pay for additional insurance or pro - vide collateral other than the residential units to protect loan institu- tions in case of fire or other losses. Natural Resources Existing Conditions There are no significant commercially valuable natural resources on the site, nor is there any present use of natural resources on the site. Impacts Construction of the buildings would consume natural resources, including energy and building materials such as wood, concrete, steel, aluminum, glass, copper and other materials of varying scarcity. Long -term energy use is discussed in the energy section of this EIS. Mitigating Measures None. Unavoidable Adverse Impacts Building materials and energy will be consumed during construction. Long- term energy use will occur due to project occupancy. 93 C. ELEMENTS OF THE HUMAN ENVIRONMENT Population Existing Conditions The 1980 population of the City of Tukwila, based on the 1980 census, was 3,578. The population of the City, which had declined by 209 between 1970 and 1976, increased by 278 between 1976 and 1980. Since 1980, the population of the City has increased to 4,627, including the 1985 Crestview annexation. From 1970 to 1980 the City experienced a two percent population increase com- pared to a 9.5 percent increase for King County as a whole, a seven percent decline in Seattle, an 18 percent increase in Renton and an 87 percent increase in Des Moines. The site vicinity (defined by SR 518, Interstate 5, South 178th Street, Military Road and 42nd Avenue South) had a 1980 popula- tion of 2,578, which was approximately 12% less than its 1976 population. Impacts The population for the proposed project was estimated by multiplying the number of dwelling units proposed by 1.96, which was the 1980 average house- hold size in the City of Tukwila'. Thus, assuming full occupancy, the esti- mated population of the project is 212 persons. Based on population distribution by age in the 1980 census, it is estimated that 27 school age children would reside in the project. The project would average approxima- tely 1 -1/3 bedrooms per unit. This estimated population increase represents a 4.5 percent increase in the total number of people residing within the City. Mitigating Measures None. Unavoidable Adverse Impacts None. Housing Existing Conditions No housing exists on the site at present. In March 1985, following the Crestview annexation, the City of Tukwila had a total of 2,472 dwelling units. By comparison, the 1980 housing count in the City was 1,938 dwelling units which was 265 more units than recorded in 1970, or an increase of 16 percent for that ten year period. Between 1980 and 1983, 130 more units were constructed for an additional seven percent increase. By comparison, Renton and Des Moines experienced three and 19 percent increases respectively during the same period. 94 Sixty -three percent of the existing housing units in Tukwila are multi- family. However, there are no multi - family units in the immediate vicinity of the project site, which is characterized by undeveloped land and single family detached residential dwellings west of and upslope from the project site. Impacts The project would add 108 dwelling units to the City's present housing stock, for a four percent increase in total dwelling units. It would increase the percentage of multi - family housing units in Tukwila from 63 percent to 67. percent. The multifamily residential buildings would represent a significant change in the scale and density of housing in the immediate site vicinity. The pro- posed density of 15.25 dwelling units per acre contrasts with the three to five dwelling units per acre in the surrounding single family neighborhood. The three - story, six -unit structures, while not directly visible from most nearby single family homes, would be substantially larger than other nearby structures. With the site's 15 -35 foot grade differential from 53rd Avenue South, building roof lines will extend up to 10 feet above street grade on 53rd Avenue South and up to 30 feet above street grade on Slade Way. However, nearby houses are located a minimum of 20 feet above the top of the proposed roof peaks, so no view blockage would occur. As described in the Land Use section of this FEIS, the buildings would be legal non - conforming uses since the site is zoned for single family use. As such, there would be restrictions on the extent to which the buildings could be structurally altered. Mitigating Measures 1. The proposed site plan provides a landscaped buffer along the western edge of the property, which would partially screen the development from com- muters on Slade Way and 53rd Avenue South and from residences in the McMicken Heights area. 2. Location of the units along the eastern portion of the site and the grade differential between 53rd Avenue South will provide topographic separation of the units from most single family homes in the area. Unavoidable Adverse Impacts 1. The project's character, including density and scale, would differ substantially from that of the surrounding single family neighborhood. 2. Property owners will be subject to the conditions of a legal non- conforming use. 95 Transportation /Circulation Vehicular Transportation Generated Existing Conditions Figure 10 depicts the street and freeway system in the site vicinity which provides access to and from the general Puget Sound /Seattle area as well as the local Tukwila /McMicken Heights neighborhood. Interstate 5 (I -5) provides the major north -south traffic corridor for regional travel in the site vicinity while Pacific Highway S., west of the site, provides some regional and more local through travel in the area. To the north of the site, SR 518/I -405 provides an east -west traffic link bet- ween Burien and Renton as well as direct access into Seattle- Tacoma International Airport. The City of Bellevue and other points on the east side are reached via I -405. More immediate to the site, Klickitat Drive provides a collector arterial function between and including 51st Avenue S. north of SR 518 and Southcenter Parkway. It is a two -lane street with four to six feet of paved and gravel shoulders in the vicinity of 53rd Avenue S., and the project site. Its road- way surface is in good condition. Except for the SR 518 eastbound off -ramp, 53rd Avenue S., and the 1 -5 southbound on -ramp, there are no other direct access locations onto Klickitat Drive. Adjacent land use to the north and east of Klickitat Drive is primarily state highway right -of -way, while that to the south and west is residential land use without direct access. 53rd Avenue S., south of Klickitat, rises southbound at approximately nine to 12 percent to South 160th Street. It is in fair to good condition with ade- quate gravel shoulders. Its intersection with South 160th Street is a "T" intersection with the south and west legs controlled by STOP signs. South of 160th Street, the roadway curves to the east, becoming Slade Way which con- tinues on a steep downgrade about 15 -20 percent to the east and narrows as it turns sharply to the south near I -5. The section of Slade Way on the 54th Avenue South alignment is a very narrow section, little more than one lane in width. Additionally, shoulders are narrow to nonexistent with a tree growing near the edge of the pavement along the east side of the road. Farther south, Slade Way /54th Avenue South, swings west again and becomes 53rd Avenue South, which provides local access to an established residential area. The section of roadway near 166th Street has recently been widened by the City of Tukwila to a standard 26 -foot wide section. South 160th Street, South 164th Street and South 170th Street provide the primary east -west local access roads in the area to the west between the pro- ject site, Military Road and Pacific Highway South. These streets are generally two -lane residential roadways in fair to good condition, with some local exceptions such as potholes and /or poor pavement. Shoulder width, which is narrow in places, is often used for residential vehicular parking. In general, residences in the vicinity front relatively close to the roadway edge, typical of numerous established medium density residential neigh- borhoods throughout the Puget Sound area. 96 4 4 -WAY STOP W /BEACC)N Nn0 iH 154TH ST H Fq 160TH ST PROJECT SITE In 164TH 5T Inf 166TH 5T 4N SHARP CORNER/ NARROW STREET 5 T > N 0 N 170TH 5T f N 176TH ST LEGEND: 0 - SIGNAL S -STOP SIGN -MULTI -LANE (• OF LANES) S 178TH ST 0 I' 'D /ft Yew s a a a S TWA/VER 8l. VD 180TH 5T 0 a S VALLEY VIEW ESTATES FIGURE 10 VICINITY STREET SYSTEM The 97 Military Road is generally a two -lane roadway, running northwest to southeast, with left -turn channelization provided at selected intersections. Traffic signals control intersections with South 164th Street /42nd Avenue South as well as South 176th Street. It is currently in good condition within the project study area. Traffic Volumes Current traffic count information was collected from the City of Tukwila and King County. The traffic volumes represent counts taken in 1981, 1982 and 1983. Where available information was incomplete, the TRANSPO Group esti- mated the current traffic volume based on neighboring volumes and field observations. Figure 11 illustrates these existing daily traffic volumes. As shown in Figure 11, the vicinity streets carrying the highest traffic volumes are in the Southcenter Parkway /Southcenter Boulevard area where volu- mes are typically in excess of 20,000 vehicles per day (vpd) . West of the project site, traffic volumes on most local streets range from 200 vpd to about 4000 vpd. Most fall within the 500 to 2100 vpd range. This is typical of established residential neighborhood traffic patterns where some streets function as neighborhood collectors, such as South 160th Street, South 170th Street and 53rd Avenue South, adjacent to the project site. Other streets such as South 164th and South 166th Streets function in a more locally - oriented manner, primarily serving the transportation needs of residents on those streets. 53rd Avenue South, adjacent to the project site carries about 2200 vpd; however, south of South 160th Street, where 53rd Avenue transitions into Slade Way, the volume drops sharply to about 200 vpd. This indicates that the primary travel pattern is to the west from 53rd Avenue to South 160th Street. 160th Street carries about 2100 vpd near 53rd Avenue South. Klickitat Drive near 53rd Avenue South and the project site carries between 13,000 - 15,000 vpd, growing to over 20,000 vpd south of the I -5 southbound on -ramp, which is consistent with volumes observed on many other collector arterials. The TRANSPO Group made evening peak period traffic counts at the intersec- tions of 53rd Avenue South with South 160th Street and Klickitat Drive as well as Klickitat Drive with the southbound I -5 on -ramp adjacent to the pro- ject. These volumes were generally about nine to 10 percent of the daily traffic volume estimates shown on Figure 11. Techniques have been developed to assess the levels of congestion that result with different street and traffic volume conditions (See Appendix E). These techniques refer to levels of service (LOS) which range from LOS A which is very good, to LOS F which reflects a traffic flow that has deteriorated to a start - and -stop condition: ° LOS A - Free Flowing; ° LOS B - Average overall speeds drop due to intersection delay and intervehicular conflicts. Delay is not unreasonable; 98 99 o LOS C - Traffic flow still stable with acceptable delays; o LOS D - Beginning to tax capabilities of street section. Approaching unstable flow. Delays at intersections may become extensive with some cars waiting two or more cycles; o LOS E - Service volumes at capacity. Average overall traffic variable. Unstable flow and continuous backup on approaches to intersec- tions; o LOS F - Forced flow. All intersections handling traffic in excess of capacity. Vehicular backups extend back from signalized intersec- tions. in urban areas, most traffic engineers design improvements to operate at LOS C, but consider LOS D acceptable during peak periods as long as these con- ditions do not extend longer than one hour within the peak period. Currently, it is estimated that the intersections counted by the TRANSPO Group operate at acceptable levels of service during the PM peak hour. The busiest of these intersections was the intersection of 53rd Avenue South with Klickitat Drive. TRANSPU's level of service calculation indicated that right and left turns from northbound 53rd Avenue South are currently operating at LOS C. This indicates that delays experienced by drivers attempting to make these movements are within an average range, and not uncommon to numerous other locations throughout the area. Left turns from Klickitat onto south- bound 53rd Avenue were calculated to operate at LOS A, indicating little or no delay. While these calculations indicate average conditions within the peak hour, observations by the TRANSPO Group indicated that sporadic backups behind left- turning traffic from Klickitat to 53rd Avenue extended to as many as eight or nine vehicles at times; however, these backups only lasted a minute or less as a maximum, typically clearing within a few seconds after the lead left -turn vehicle completed its movement. In addition, the wide lane and shoulder for westbound traffic on Klickitat allowed some vehicles to pass the left- turning vehicle on the right. While existing striping does not encourage this movement, it would appear that adequate space is available to restripe the east leg of Klickitat with little if any widening to allow for left -turn channelization, thereby eliminating delays to through traffic as a result of left - turning traffic ahead. Traffic accidents experienced over the last three years show a consistent pattern of rear -end accidents at this location which would be reduced significantly by such an improvement. All other intersections in the immediate site vicinity operate well within the accepted range of delays for LOS A conditions. Forecast Traffic Volumes Without the Project Future non - project traffic reflects growth associated with general develop- ment in the area, as well as specific known projects which would be located in the vicinity and generate additional traffic volumes to the roadways. Discussions with the City of Tukwila staff indicate that there are no other specific projects in the immediate area which would significantly impact traffic on roadways near the Valley View Estates Site. The City of Tukwila Transportation Improvement Plan, published in 1979, as well as existing traf- fic count history in the area were referenced in developing the expected 100 annual traffic growth on roadway links near this project. Based on this research, traffic in the residential area ori top ,of the•hill to the west, as well as immediately surrounding the project,• is, forecasted to grow at about one percent compounded annually for, the four year period ending in 1987. This reflects the relatively stable neighborhood and its past volume growth history. Traffic volumes along the Pacific Highway South corridor would be expected to grow at about two percent per year compounded annually. To the east, in the Southcenter vicinity, traffic volumes growth is forecasted about 4.5 percent per year traffic growth between 1979 and 1990. However, between 1979 and 1982, traffic volumes have grown between seven and 18 percent annually. In this area, the TRANSPO Group utilized a seven percent annual compound growth rate to reflect both the recent high growth trend and the long range, 1990 forecast. Planned and Programmed Traffic Improvements In order to accurately evaluate traffic impacts at the time the project is constructed, an attempt was made to determine the street system which would likely be in place for the project target year even if the project were not constructed. The current 1984 through 1989 Six Year Transportation Improvement Program (TIP) for the City of Tukwila identified the following projects in the immediate vicinity which would impact or be impacted by the proposed Valley View Estates development. Grading, drainage, light bitumi- nous surface treatment, A.C. or P.C.C. pavement, sealcoat, curb, gutter, sidewalks, lighting and signing, have been proposed for the following road segments: o 160th Street, 51st to 53rd Avenue (1987) o 54th Avenue, Slade Way to 166th Street (1988 -90) o 53rd Avenue, 160th Street to Klickitat Drive (1987) o Slade Way, 54th Avenue to 160th Street (1988 -90) These improvements appear to be contingent on the formation of Local Improvement Districts (LID) or developer funding. Thus, while sidewalks are proposed in the area, without developer contributions, they are not likely to installed. Portions of 54th Avenue near 166th Street are currently being improved, including widening and curve improvements to eliminate a sharp, narrow curve between 166th and 54th. Projected Traffic Volumes and Distribution A trip, generation rate of 8.0 daily vehicle trip ends (VTE) per dwelling unit was selected for use in the study both to reflect local experience with simi- lar developments and to indicate a worst case assumption with regard to potential traffic impacts. For the purposes of this study, worst case is defined as the high end of the reasonably expected range of conditions. Corresponding to this daily trip generation rate, a PM peak hour rate of 0.8 VTE per DU was utilized which •is. consistent with numerous observations in residential areas which indicate that approximately 10 percent of the daily travel occurs during the evening peak hour. 101 Based on this trip generation rate, the TRANSPO Group estimates that approxi- mately 900 daily vehicle trips and 90 evening peak hour vehicle trips would be generated by this 108 unit project at full occupancy. Figure 12, Project- Generated Traffic Volumes, depicts the daily and evening peak hour traffic volumes associated with the distribution of travel described above on the local roadway system. Evening peak hour traffic assignment is generally more heavily oriented toward routes serving primary employment centers (i.e., Seattle I -5 north and SR 99 north; Bellevue /Renton 1-405 east). Daily traffic, in addition to worker commute trips, reflects social /recreational and retail travel, i.e., to and from community retail centers located at SR 99 and 160th, along Military Road at South 164th and in the Southcenter /Parkway Plaza vicinity. Traffic volumes associated with each trip purpose were generally assigned to the one or two primary traffic carrying routes between the development and the trip destination to reflect a worst case traffic volume on these primary traffic - carrying facilities. While it is acknowledged that some traffic may use other minor roads in the vicinity (i.e., 164th Street and 166th Street and others), these traffic volumes would be very minor and would cause no noticeable increase in either traffic or congestion at intersecting roads. Figure 13 depicts the impact of the project traffic on traffic conditions likely to exist in 1987, showing both 1987 daily traffic volumes with and without the Valley View project. TABLE 8 Street Traffic Generation Impacts Created by Proposed Project System Vehicle Increase Percentage per day Increase 53rd Avenue: 158th Street to Klickitat Drive 160th Street: 53rd Avenue to 51st Avenue 160th Street: 42nd Avenue to 51st Avenue Slade Way /54th Avenue: 170th St. to project 170th Street: 51st Avenue to 53rd Avenue +530 vpd +340 vpd 300 vpd + 30 vpd + 30 vpd + 23% + 16% + 16% + 15% + 6% It should be noted that the 15 percent and six percent increases shown for Slade Way, 53rd Avenue South and 170th Street between 51st Avenue and the project are a result of a total of 30 vehicles assigned to that route on a daily basis. The relatively high percent increases are due to the low traf- 102 15 100 PEG V 4 10 120 154TH ST u1 10 260 PEG 30 PEG 80 PEG 30 160TH ST 20 6EG NEG CIO 560 10 PEG 10 4 20 160 EEO r 1133'- 133 EEO 700 1133 570 EEO 25 An II° 740 PROJECT SITE Iffil m 1E3 MEI 164TH ST m' 20 m 166TH ST m 50 PEG PEG N N B3 C3 NEG 30 110 en N m' 170TH ST 3 m 10 40 LL 176TH ST LEGEND: ^-37,,— PM PEAK HOUR VOLUMES 100 DAILY VOLUMES NEG - NEGLIGIBLE 80 178TH ST NEG 20 15 105 tC 20 150 25 180 SOUTHCENTER MALL 5 50 10 90 15 105 10 S TRANDER &VD NEG 20 Qi NEG PEG PEG 0 180TH ST PEG 10 170 JPEG PEG 0 5 JO VALLEY VIEW ESTATES FIGURE 12 PROJECT - GENERATED TRAFFIC VOLUMES The rRANSI 103 1987 DAILY TRAFFIC VOLUMES WITH & WITHOUT PROPOSED PROJECT 104 fic volumes currently using these roadways. The 160th Street corridor would be the primary local street artery for traffic destined or originating locally west of the site, including Pacific Highway South. Although the 16 percent increase in traffic volumes on this route will be noticeable and could be considered substantial, the roadway is fully capable of carrying the forecasted traffic both with and without the proposed project. Therefore, significant adverse impacts associated with these increased traffic volumes on roadway capacity are not anticipated. The project is expected to generate a traffic volume increase of 23 percent over projected 1987 conditions without the proposed project. Again, however, this increase is well within the traffic - carrying capabilities of the two -lane roadway, and no significant adverse impacts would be anticipated. Typically, 5,000 to 7,000 vpd are con- sidered desirable maximums for traffic volumes on similarly functioning streets. It should be noted, however, that "desirability" varies between neighborhoods and depends on many factors including driver expectations and conflicting pedestrian activity. Although existing roads can easily accom- modate additional traffic generated by the proposed project, residents may experience the additional traffic as an inconvenience and undesirable, par- ticularly since a significant proportion of project traffic will travel through residential areas to the west of the site. The intersection of 53rd Avenue South and Klickitat Drive would experience no significant decrease in level of service as a result of project - generated traffic. The critical movement from a congestion standpoint would be the northbound left turn from 53rd Avenue S. This movement would operate in the LOS 0 range both with or without the proposed project. Under existing con- ditions, it operates at LOS C. The observed westbound left -turn queues which occasionally back up to as many as eight or nine vehicles now could become somewhat longer as a result of non - project traffic growth (possibly increasing to about 10 -12 vehicles). The incremental difference in this queuing situation as a result of this project would seldom be noticeable. Traffic volumes on Klickitat Drive both east and west of 53rd Avenue South would increase approximately two percent as a result of project - generated traffic. This is well within the five percent variation observed in daily traffic volumes. The locations of access driveways proposed for the project off 53rd Avenue South and Slade Way appear to pose no special problems or concerns relative to either sight distance or traffic volumes. However, in response to com- ments on the Draft EIS, the traffic consultant has recommended that a 30 foot wide level platform be constructed beyond the stop line at the 53rd Avenue South driveway to enhance visibility of drivers exiting the project. About three - fourths of the total daily project traffic will utilize the northerly driveway along 53rd Avenue South, while about one - fourth will utilize the two driveways along Slade Way. The westerly driveway off Slade Way is a dead end access to 12 of the units, while the easterly driveway is a through access continuing northward to the 53rd Avenue access point. Mitigating Measures 1. A left -turn lane for westbound -to- southbound left turns from Klickitat Drive to 53rd Avenue South will be provided to eliminate conflicts between left- turning traffic and westbound through traffic. Based on review of 105 available accident data and pattern of accidents, this improvement is con- sidered desirable to improve existing intersection operation as well as in the future with or without the project. 2. Project driveway locations will be at least 150 feet away from the nearest intersection as shown on the current site plan. 3. The project driveway onto 53rd Avenue South could be designed to . include a level platform extending 30 feet beyond the driveway stop line to enhance the visibility of drivers exiting the project. Unavoidable Adverse Impacts The project will generate increased traffic through residential areas to the west of the site. Parking Existing Conditions Minor on- street parking has been observed in the immediate vicinity of the project site given the low- density residential development in the area. To the west, in McMicken Heights, between the project site and Military Road, as well as between Military Road and Pacific Highway South, on- street parking was generally sparse and associated with close fronting residences along the various streets. There was little evidence of any parking encroaching into the travel lanes. No parking was observed along Klickitat Drive near the project site. There is currently no frontage of any traffic - generating acti- vity on this street. Impacts One hundred and eighty -two (182) parking spaces will be supplied on -site adjacent to the residential units for a ratio of 1.5 spaces per dwelling unit. Proposed parking supply exceeds Zoning Code requirements and should meet "everyday" parking demand, as well as provide additional spaces to accommodate parking needs for social activities. Allowing for some on -site overflow in the site design will help ensure that project parking demand will not noticeably impact Slade Way or 53rd Avenue South, even during peak demand periods. According to the Traffic Report, this assumes parking of recreational vehicles is not permitted on -site. Mitigating Measures 1. Excess on -site parking for 20 vehicles will be provided to accommodate frequent parking demand conditions in excess of 1.5 spaces per dwelling unit. 2. Assignment of parking spaces to specific residential units could be prohi- bited so as to assure the flexibility needed to accommodate fluctuating demands in the primary parking areas. 106 3. Parking of recreational vehicles or trailers on -site could be prohibited to assure that residential and visitor parking flexibility is maintained. Unavoidable Adverse Impacts Minimal parking spillover could occasionally occur on 53rd Avenue South, Klickitat Drive or Slade Way due to large social events. Transit Systems Existing Conditions The project vicinity is currently well served by existing Metro Transit routes. Two transit routes pass directly adjacent to the site on Klickitat, routes 240 and 241. Route 240 utilizes 53rd Avenue South, 51st Avenue South and South 170th Street to Pacific Highway South through the residential neighborhood west and south of the site. Route 240 serves Bellevue and Burien, running on one -hour off -peak headways and half -hour peak headways. Route 241 bypasses the residential neighborhood bordering the project and continues west on Klickitat via SR 518 to Pacific Highway South. Impacts In order to reflect a worst case traffic impact analysis, all project trips were assumed to occur via auto. However, a certain small percentage of the trips to and from the project site would utilize public transit since one transit route passes by the site along 53rd Avenue and others are accessible nearby in the Southcenter vicinity. It is estimated that less than five per- cent of the total trips to and from the Valley View projects would be made by transit patrons, i.e., 50 trips (25 arrivals, 25 departures) per day. Metro Transit would likely view this impact as positive rather than adverse. Mitigating Measures The developer will work with Metro Transit to ensure a safe, convenient bus stop location for project transit patrons adjacent to the site. Unavoidable Adverse Impacts None. Pedestrian and Bicycle Travel Existing Conditions Field observations made during peak hours and at various times of the day including weekends, showed that there were no significant numbers of pedestrians or bicyclists in the immediate site vicinity. In areas where traditional activity generation exist, such as community shopping centers, more activity was observed; however, it was still generally observed to be light. A few pedestrians were observed in the residential neighborhood to the southwest; however, the activity again would be described as very light. 107 The 1979 Transportation Improvement Plan indicated that there are no bikeways along the arterial system within the City and no current plans to add them along major streets in the project vicinity. Physical factors, such as steep terrain, limit bicycle use as a practical commuting mode for most potential users. The 1984 -89 Transportation Improvement Program does propose sidewalks along area streets, subject to developer L.I.D.'s as indicated in the pre- vious discussion of Planned and Programed Traffic Improvements. At the pre- sent time there are no sidewalks in the area and roadway shoulders are limited. Impacts A small percentage of the total travel associated with the Valley View Estates residential development would be expected to be generated by pedestrians or bicyclists. Its relative isolation from any designated bicycle facilities would tend to discourage this type of travel for most trip purposes. Some pedestrians could be expected to walk west from the site on South 160th Street, including school children walking to the bus stop on 51st Avenue South and those walking to the planned Crestview Park facilities .2 miles northwest of the site. Since the shoulder along South 160th Street between the site and 53rd Avenue South is presently narrow in places, the traffic consultant has recommended that it be widened to a minimum width of four feet (see responses to transportation - related comments on the DEIS.) By City ordinance, sidewalks will be required around the edge of the site abutting public streets, (i.e. along Slade Way and 53rd Avenue South) which will facilitate pedestrian travel along these street frontages. With respect to pedestrian travel within the development, the traffic con- sultant has suggested that a gravel path or sidewalk could be provided along the east edge of the circulation aisle with a possible crosswalk installed at the north entrance to the primary parking area so that pedestrians can walk through the site separated from project traffic. Mitigating Measures 1. By City ordinance, sidewalks will be required along the edge of the site abutting public streets (i.e., Slade Way and 53rd Avenue South) which will facilitate pedestrian travel along these street frontages. 2. Roadway shoulders on South 160th Street between the site and 51st Avenue South could be widened a minimum of four feet to facilitate safe pedestrian access to 51st Avenue South. 3. A gravel path or sidewalk could be provided along the east edge of the on- site circulation aisle, with a possible crosswalk installed at the north entrance to the primary parking area so that pedestrians can walk through the site separated from project traffic. Unavoidable Adverse Impacts Pedestrian walking to destinations west of the site, including school children, would be required to walk along the shoulder of South 160th Street. 108 Traffic Hazards Existing Conditions Traffic accident data over the period from 1980 through September 1983 was examined based on information supplied by the King County Traffic Engineer and the City of Tukwila. The average annual accident occurrence is depicted on Figure 14 for intersections in the project vicinity. Near the site, the intersection of 53rd Avenue South with South 160th Street did not experience a reported accident in the study period. An average experience of 2.7 acci- dents annually occurred at 53rd Avenue South and Klickitat Drive, while 0.3 accidents per year occurred at the intersection of Klickitat Drive with the I -5 southbound ramp and the intersection of Klickitat Drive with Southcenter Parkway. In the entire study area depicted on Figure 14, approximately four percent of the accidents occurring during the study period involved pedestrians. Of these, nearly half of the pedestrian accidents occurred on 170th Street at Military Road and 51st Avenue South. Since this is a Metro bus route, it is likely that some accidents may be attributable to pedestrians associated with transit, although the accidents records were not detailed enough to discern this. The accident rates at a number of key intersections in the study area which experienced at least one accident per year on the average were as follows: Location Accidents per Million Entering Vehicles (Acc /MEV) o 53rd Avenue S. and Klickitat Drive o 52st Avenue S. and S. 160th Street o 51st Avenue S. and S. 170th Street o Military Road and S. 160th Street o Military Road and S. 170th Street o Military Road and S. 176th Street 0.5 1.4 1.1 0.6 1.1 1.2 Typical urban area accident rates for both signalized and unsignalized inter- sections range from 0.5 to 2.0 Acc /MEV. The above accident rate data reveal no significant safety hazard at any of the above intersections based on acci- dent experience. It is acknowledged, however, that all accidents are not necessarily reported at every location. Additionally, even those accidents reported typically require a minimum property damage estimate of $300 prior to being added to the accident record files for most jurisdictions. Concern has been raised by City of Tukwila staff and neighbors regarding the westbound -to- southbound left -turn movement from Klickitat Drive to 53rd Avenue S., including the number of rear -end accidents that have been asso- ciated with this maneuver. Reportedly, through vehicles westbound on Klickitat have rear -ended vehicles waiting in the queue caused by delays to left- turning traffic. Examination of the available accident data indicated a repeating pattern of these rear -end accidents. However, the above accident rates indicate that the intersection as a whole is less hazardous than many other intersections in the immediate area. Installation of a left -turn lane for westbound approaching traffic at the intersection discussed above would eliminate much of the potential for these types of accidents. 109 7. J 0.7 1.8 154TH ST 4.4 UM 2.9 1.1 2.9 1.8 2 2 160TH ST 0.4 0.7 4.71 10.4 10.7 r 2.7 2 7 1.3 10.4� PROJECT SITE 10.4 0.7 164TH ST 0.0 0.4 BEI J.. 166TH ST 4.0 1.8 0.4 2.14 170TH ST 1' 2.21 6.5 176TH ST VALLEY VIEW ESTATES 1 3.3 N f I ti 1713TH 5T 0.0 NORTH 0.3 W STRMOER BLVD C 180TH ST FIGURE 14 AVERAGE ANNUAL ACCIDENTS (Jan 1981 to Sep 1983) The TRANSPO Grove 110 Impacts There do not appear to be any unusual safety hazards associated with the design or siting of the Valley View Estates multi - family housing development, and consequently, the development is not expected to measurably increase the safety hazard potential on most surrounding streets. In general, traffic accidents in the vicinity may be expected to increase in proportion to the increase in traffic volumes on streets surrounding the proposed development. However, it is difficult to estimate exactly how large this increase may be. Although accidents at nearby intersections would increase at a constant rate, project traffic is not expected to significantly increase the potential for rear -end accidents at the 53rd Avenue South /Klickitat Drive intersection. There will be an increased potential for accidents associated with the dri- veway openings for the development site, due to new turning movement conflicts. However, potential conflicting traffic volumes at these locations indicate that the increase would be very minor. Although pedestrian traffic along streets in the vicinity has been observed to be very light, there would be an increased potential for vehicle - pedestrian conflicts along these roadways. The contribution of project traf- fic along most roadways in the neighborhoods to the west and south would be small, however, and therefore the potential increase in accidents attribu- table to the project - generated traffic would be correspondingly small. To minimize the potential for pedestrian /vehicular conflicts within the develop- ment, speed bumps could be installed within the circulation aisle (no closer than every 200 feet) to control traffic speeds on site. Mitigating Measures 1. A left -turn lane for westbound -to- southbound left turns from Klickitat Drive to 53rd Avenue S. will be provided to eliminate conflicts between left- turning traffic and westbound through traffic. This improvement is considered desirable with or without the project. 2. Speed bumps could be installed within the on -site circulation aisle (no closer than every 200 feet) to control traffic speeds on site. Unavoidable Adverse Impacts Traffic accidents will increase in some proportion to the increase in traffic volumes on streets surrounding the proposed development. Public Services Fire Service Existing Conditions Fire protection in the site area is provided by the Tukwila Fire Department. Emergency response time to this area is estimated to average three to four minutes. The fire rating in Tukwila is Class 4 on a scale of 1 to 10, with 1 as excellent. 111 Impacts The proposed condominium development would increase the demand for fire pro- tection. This demand can be adequately met by the City's Fire Department. The proposed on -site system would comply with City of Tukwila fire flow and hydrant- spacing requirements, as well as with the requirements of the Washington State Department of Social and Health Services. According to Washington Survey and Rating Bureau criteria, approximately 2100 gpm (see appendix for calculations) is the required fire flow for multi - family deve- lopments of the type proposed. The proposed system would meet the minimum criteria. Mitigating Measures 1. One approved fire extinguisher will be provided in each unit. 2. Smoke detectors will be installed per the Uniform Building Code Section 1210. 3. Certain driving and parking areas may be declared "fire lane - no parking" areas per Ordinance 1110. 4. A 20 -foot wide unobstructed driving_ lane with a 35 -foot turning radius will be required through the site. 5. Protective curbs or guard posts for all sprinkler valves, hydrants, gas meters and transformers will be provided. Unavoidable Adverse impacts There will be an increase in demand for fire protection. Police Service Existing Conditions Police protection in the vicinity is provided by the City of Tukwila Police Department. Emergency response time for the area is three to five minutes on the average. According to the Police Department's Operations Commander, the present level of police service in the City is adequate. Impacts The project is not likely to necessitate the acquisition of additional per- sonnel, but could cause slightly increased response time throughout the City. The Police Department has indicated that adequate on -site parking minimizes traffic accidents, auto thefts and car prowl incidents. While the Department, in its comment letter on the DEIS, recommended that two on -site parking spaces should be provided per unit, the Traffic consultant considers the proposed ratio of 1.7 spaces per unit adequate to meet demand, so long as recreational vehicles are parked elsewhere. 112 Mitigating Measures 1. A close working relationship between the developers and the Police Department's Crime Prevention Officer will be maintained throughout the planning and building phases of this project to minimize crime and per- sonal safety risks potentially associated with the project. 2. Adequate parking on site will be provided to minimize off - street parking and associated vehicle and pedestrian accidents, auto thefts and car prowl incidents. Unavoidable Adverse Impacts Response times to police calls could increase slightly throughout the City. Schools Existing Conditions The site is within the Highline School District. The site vicinity is served by McMicken Elementary School, Chinook Middle School and Tyee High School. The current enrollments and capacities of these schools are indicated in the tollowing table: TABLE 9 Schools Serving Vicinity of Site4 School3 Enrollment (Oct. 1984) Capacity2 McMicken Elementary' 356 425 Chinook Middle School 441 875 Tyee High School 780 750 1 Data for McMicken Elementary is current as of 3/19/85. 2 Capacity is based on Highline School District Standards of 25 students per classroom. 3 Portable classrooms are utilized in schools where enrollment has exceeded capacity. 4 Telephone conversations with Dorris Brown, Facilities and Planning Office for Highline School District. June 18, 1984 and March 19, 1985 (relative to McMicken Elementary) 113 Impacts Based on the population distribution by age provided in the 1980 census, it is estimated that approximately 27 school aged children could be expected to reside in the proposed development. McMicken Elementary School can easily absorb the estimated increase in enrollment created by the proposed develop- ment. Approximately seven high school -aged children could be expected to reside in the proposed development, which would represent an increase in enrollment at Tyee High School of less than one percent. These seven students could contribute to the demand for one additional classroom or portable classroom. Mitigating Measures None. Unavoidable Adverse Impacts Slight increase in demand for an additional classroom at Tyee High School. Parks and Recreation Existing Conditions The neighborhood in which the site is located is referred to as Crestview in the City of Tukwila Park and Open Space Program, 1976 -81. The neighborhood is bounded by I -5, SR 518, 42nd Avenue South, Military Road, and South 178th Street. Currently there are no public recreational facilities within this neighborhood. Public facilities that are within two and one -half miles (driving distance) of the site are listed in Table 10. 114 Facility Thorndyke Elementary TABLE 10 Existing Recreational Facilities Distance from Site Facilities 1.3 miles Playground, playfields, indoor /outdoor courts 1.1 miles 2 tennis courts 1.4 miles Playground, playfields, indoor /outdoor courts 1.6 miles Playground, indoor/ outdoor courts. King Co. McMicken Heights McMicken Elementary Valley View Elementary King Co. Valley View Ridge Park 2.3 miles Tyee High School Chinook Junior High Bow Lake Elementary King Co. South Central Pool Foster High School Crestview Park 2.3 miles 2.4 miles 2.3 miles 1.1 miles 4 tennis courts; 3 soccer fields, 4 base- ball fields, community building, picnic area Shares facilities with Valley View Ridge Park Shares facilities with Valley View Ridge Park Playground, playfields, indoor /outdoor courts Indoor swimming pool 1.6 miles Track, tennis courts, playfields 0.2 miles Undeveloped park with trails The City of Tukwila adopted a Long Range Park and Open Space Plan in April 1984. Its six year capital improvement program proposes the development of the 11.0 acre Crestview Park located within the City limits immediately northwest of the site. Development would include a parking area, paved and bark trails, one tennis court, a multi - purpose play court, picniking area and a "water feature development." Park development would occur in two pha- ses, with the final phase occurring in 1987. 115 The City of Tukwila 1976 -81 Park and Open space Program included a summary of park standards for neighborhood and community parks and playfields, which are as follows: Park and Playfield Space Standard TABLE 11 Park Standards Neighborhood Park Neighborhood Playfield Community Park Community Playfield Service radius i - # mile * - i mile 1 - 2 miles 1 mile (walking distance) Population served 3000 -7000 5000 20,000 15- 25,000 Size range. 3 -10 acres 3 -7 acres 20 -25 15 -25 Acreage /Population 1 -2 a./ 1.25 a. / 1 -1.4 a./ 1.4 a./ 1000 p. 1000 p. 1000 p. 1000 p. The proposed Crestview Park facilities would generally meet the neighborhood park and playfield standard for this area. The park site lies on the outside of the service radius for the Crestview neighborhood (relative to the Community Park and playfield standards). The project site has been identified as an "Open space study area" in the City's "Long Range Park and Open Space Plan." A "Tukwila Urban Open Space Action Study" is recommended which would analyze undeveloped areas to deter- mine the feasibility and desirability of preserving as open space. The Plan utilizes the definition of "open space" accepted by the U.S. Department of Housing and Urban Development which is as follows: "Land and /or water areas undeveloped or primarily undeveloped, which serve the specific urban areas of (A) providing park and recreation opportunities; (8) conserving valuable natural resour- ces; and /or (C) structuring urban development and form, and which are consciously being acquired or publicly regulated to serve such functions.. While vacant or undeveloped land has the poten- tial for being classified as open space, that should be done only after a conscious decision has been made to purchase or regulate these lands." The Plan recommends that the open space study be prepared prior to 1990. Presently, there are no plans by the City to acquire the property for open space use. Wooded and steep hillsides are presently addressed by Tukwila's Comprehensive Land Use Policy Plan and SEPA policies. 116 Impacts The proposed project would attract approximately 212 new residents to the northeast portion of the Crestview neighborhood which will increase demand on local recreation facilities. The site is within the service radius of existing playfields and a proposed community park. However, pedestrian and bicycle access between the site and existing and proposed recreational areas are poor. The proposal includes a 6,175 square foot, fenced play area for children, as well as a minimum of 200 square feet of recreation space per unit. Section 18.60.200 of the 1982 Tukwila Zoning Code, "Recreation Space in Multiple Family Districts," prescribes recreation standards for multi- family develop- ments. Since the proponent applied for a building permit prior to the effec- tive date of the 1982 Zoning Ordinance, these requirements would not apply to this project. However, the proponent has committed to meeting the current requirements, which include the following: o For each proposed dwelling unit, a minimum of two hundred square feet of recreation space shall be provided. 0 0 Apartment complexes with dwelling units of two or more bedrooms shall pro- vide adequate recreation space for children. Such space shall be at least twenty -five percent, but not more than fifty percent of the total recreation space required and shall be designed, located, and maintained in a safe condition. No more than fifty percent of the open or uncovered recreation space requirement may be located on slopes greater than four horizontal to one vertical (four -to -one slope). o Front, rear, and side yard setbacks required by the applicable zoning district shall not qualify as recreation space. o Adequate fencing, plant screening, or other buffer shall separate the recreation space from public streets, parking areas, or driveways. Under the current Zoning Code, it is the duty of the Planning Commission, acting as a Board of Architectural Review, to review all recreation space plans for design, location, function, adequacy, and compliance with all of the applicable standards prior to issuance of the building permit for any multiple family structure, complex, or development. As described in the Noise Section of this FEIS, recreation areas on the pro- ject site other than the children's play area will be exposed to noise levels that are characterized by EPA as having "significant adverse impacts," i.e., Ldn of 65 -70 dBA. Potential noise mitigation for these areas is discussed in the Mitigating Measures for noise impacts. Development of the site will foreclose the possibility of its being recom- mended as permanent open space by the Tukwila Urban Open Space Action Committee. 117 conlas own iiiiiiiiiiiiiiiiiiiiii •i••iiiiii•iwiiiiiii THE MITHUM ASSOCIATES CPO 2000112tH AVFNU Nf BELLEVUE. VASHiNG10N %8004 206 454 3344 NJG��f�I�C'l WEN rEE4ATIEg FIGURE 15 Mitigating Measures 1. A 6,175 square foot children's play area will be provided including an open play area, sandbox, and other play equipment. 2. A minimum of 200 square feet of recreation area per dwelling unit will be provided in addition to all other requirements of Section 18.60.200 of the Zoning Code, "Recreation space in Multiple Family Districts." Unavoidable Adverse Impacts 1. The project will increase demand on local park and recreation facilities. 2. Project residents will be exposed to significant adverse noise impacts in on -site recreation areas, outside the fenced children's play area. 3. The project will foreclose the possibility of the site's being considered as permanent open space by the Tukwila Open Space Action Committee. Maintenance Existing Conditions The City of Tukwila maintains public roads in the vicinity of the site. The Val -Vue Sewer District is responsible for maintaining the 12 -inch sewer which extends through the property and has an easement for the purpose. The State Department of Transportation is presently responsible for main- taining the drainage facilities which it installed during construction of 1 -5, portions of which are located on the subject site. The City of Seattle Water Department is responsible for maintaining its 60 -inch water supply line located just north of this site parallel to the site's northern boundary. Impacts The City of Tukwila would continue to be responsible for maintaining roads in the immediate site vicinity. Although the Draft EIS indicated that the City also would provide water service to the site, it has subsequently been deter- mined by the City that water would be provided instead by Water District #75 since the project site lies within its service boundaries. Thus, Water District #75 would be responsible for maintaining off -site portions of the water system. The Val -Vue Sewer District would continue to maintain its 12 -inch cast iron sewer line that crosses the site. Portions of this line will be relocated by the developer so that it will not be underneath any of the buildings within the proposed development. City of Tukwila policy prohibits placement of buildings over sewer lines. Maintenance of on -site drainage control facilities, including the proposed stormwater detention facilities, would be the responsibility of the property owners. Catch basins and oil /water separators would need to be cleaned fre- quently to assure maximum pollution separation. Continued maintenance of the off -site drainage facilities installed by DOT, as has been noted, is critical 119 to assure continued deep- seated slope stability on the hillside. Under the current proposal, maintenance of both the WSDOT drainage systems and all on- site drainage facilities would assume increased importance. Requirement for long -term monitoring of slope instrumentation by the geotechnical engineering consultant and compliance with associated remedial actions plans. Development of the project is not expected to affect the City of Seattle's 60 -inch water line that is located just north of the site. During construction, street sweeping and ditch cleaning would be undertaken by the developer. Following construction, street cleaning would be the City's responsibility. Mitigating Measures 1. Formal agreements could be required between the developer and the State of Washington regarding long term commitments for monitoring, maintenance, and repair of the WSDOT drainage systems and all stormwater and drainage facilities that could potentially adversely affect the stability of the project area. 2. The geotechnical engineer shall be retained to provide or direct long term monitoring and maintenance of instrumentation installed to evaluate the stability of the project site. 3. The developer and the property owner(s) will be responsible for main- tenance of all onsite drainage and erosion control facilities. 4. Runoff at the north side of the site will be controlled so as not to adversely affect the City of Seattle's 60 -inch water line. 5. The Contractor will ensure that trucks carrying excavation loads will be covered with canvas or tarps if necessary for dust control. 6. The developer will provide street and ditch cleaning during construction as necessary. Unavoidable Adverse Impacts The proposed project will increase the demand for long -term maintenance of all highway, drainage, sewer and water systems. Utilities Energy Existing Conditions There is no existing use on the site which places a demand on energy. 120 Impacts During construction, energy will be committed to the project in the form of equipment operation, motor fuels and manufactured materials. The type of energy consumed during this period will be typical of standard residential construction. However, multi- family construction consumes less energy per dwelling unit constructed than does single family development. According to Seattle City Light data regarding residential consumption for all- electric apartments, an average of 950 kilowatt hours (kwh) per month or 11,400 kwh annually, are consumed per unit. At this rate, the 108 residen- tial units would consume about 102,600 kwh monthly or 1,231,200 kwh annually when fully occupied. Energy expenditures in terms of transportation related to work, shopping and social purposes will create a long -term energy commitment. Mitigating Measures 1. Double - glazed aluminum windows and RO11 fiberglass insulation will be uti- lized. Insulated walls, floors, roof and glass could be used throughout all structures. (See also Noise Mitigating Measures). 2. An energy analysis of building design elements could be undertaken to assess the feasibility of reducing long -term demand, e.g., passive solar energy systems. Unavoidable Adverse Impacts There will be both short -term and long -term increases in energy use on the site. Communication Existing Conditions Telephone service to the site would be provided by Pacific Northwest Bell Telephone Company, which has the ability to supply the needed line capacity for all development in the area. Impacts Assuming the average dwelling unit requires two telephone lines, a cable unit capable of carrying 216 lines would be required. Mitigatinnc Measures 1. All telephone lines will be installed underground. 2. Installation of telephone lines will be coordinated with installation of electrical lines. 121 Highline water district intertie Water district 75 intertie Water district #75 intertie Unavoidable Adverse Impacts None. Water Existing Conditions The project is located within the service area of King County Water District No. 75, near the boundary between Water District No. 75's Service area and the City of Tukwila's water service area. Water District No. 75 and the City of Tukwila both have tie -ins to a 60 -inch City of Seattle Cedar River pipe- line, part of which parallels the northern boundary of the site. See Appendix G for a map showing the site in relation to the City of Tukwila's Comprehensive Water Plan area. Impacts Projected domestic water use for the proposed development is expected to reach a maximum of 0.04 mgd on a peak day. The DEIS indicated that the site would be served by the City of Tukwila from a City of Tukwila pressure reducing station at 53rd Avenue South. This arrangement would have necessi- tated a service area agreement between Water District No. 75 and the City of Tukwila or deannexation of the site from Water District No. 75's service area. It has subsequently been determined by the City that the site should be served by. Water District No. 75 since it lies within the District's ser- vice boundaries. District No. 75 has an existing.six -inch line that extends down South 160th Street to Slade Way. As suggested in the comment letter from District No. 75 on the Draft EIS (see Part Two), the District is interested in exploring with the City the possibility of an intertie at the City's pressure reducing station on 53rd Avenue South, and the City of Tukwila Public Works Department (Ross Earnst) has expressed willingness to meet with the District in this regard. Required fire flow for the for the project would be approximately 2,100 gpm (see Appendix G for calculations) based on the site plan and proposed building type. The proposed on -site system, which would be designed by the proponent's engineer and constructed within the private road rights -of -way, would comply with City of Tukwila fire flow and hydrant- spacing requirements, as well as the requirements of the State Department of Social and Health Services. The on -site system would be maintained by the condominium homeowners' asso- ciation. Limited short -term impacts on vehicular travel could occur near South 160th Street /53rd Avenue South if trenching were required within the public right - of -way. Brief water service .interruptions in the area could occur during construction of the system. Mitigating Measures Installation of water restrictive fixtures and devices such as flow restric- tors in new dwelling units could reduce water consumption, if such measures are deemed necessary or desirable. 122 Unavoidable Adverse impacts Short -term disruption of vehicular travel near South 160th Street /53rd Avenue South could occur if trenching for the water system is required within the public right -of -way. Sewer Existing Conditions The site would be served by Val Vue Sewer District. An existing 12 -inch cast iron sewer main runs through the site as shown on the Utility Site Plan, Figure 16. The line connects to Metro via a Hat Highlands Sewer extension. From this extension, sewage from the site would be transmitted to the Renton Sewage Treatment Plan via the Freeway interceptor, Val Vue outfall, and Tukwila Interceptor. Figure 16 depicts sewer easements across the site. Please refer to the indenture between Puget Western and Val Vue Sewer District in Appendix G. The proposed project is within Metro's Renton Treatment Plan service area. Metro has prepared a facilities plan for the Renton system with a grant from DOE and EPA, in part because the Renton Treatment plant has reached its "design" capacity and continued development is occurring within the service area. A final plan for the Renton service area was adopted by the Metro council in November 1981 and contains a recommended program for upgrading the Renton system so that water quality and health will continue to be protected. The Plan was amended on April 5, 1984 to revise the alignment for the effluent transfer system pipeline. These improvements will be on line in early 1987. Impacts The on -site sewage collection system will be designed by the proponent's engineer and will be installed as shown on the site utility plan. Six and eight inch lines would collect sewage throughout the project and connect into the existing Val Vue sewer line as shown. Projected sewage flow for the site should not exceed 0.005 mgd (including infiltration) on a peak day (see Appendix for calculations). Portions of the existing 12 -inch cast iron main will be relocated so that it will not be underneath proposed future building locations as shown on the Site Utility Plan on Figure 16. The realignment traverses the hillside higher upslope, resulting in a maximum excavation depth of approximately 20 feet. The maximum depth of excavation for the existing sewer line in this area was on the order of 15 feet. In the opinion of the geotechnical engineer, the proposed realignment of the sewer is feasible provided that the excavation is properly designed and constructed (reference the October 16, 1985 letter from GeoEngineers, Inc., presented in Appendix A). The easement agreement with the Val Vue Sewer District requires that the costs of relocating the line be paid by the District. The development will result in increased sewage flow. As stated above, the Renton Treatment Plant is currently treating more than design capacity, but 123 r-� N m 0) STORM UNE EX /STINC7 CITY OF SEA77L.6 60- /NCH W4 r6R M•NN COA?ROL MH tEX/3T/�(/4 DRA /UAGE SWAGE PROPeRTY LINE EX/.T /A14 SIN /TA,Y 3EN/ER UNE TO 06 s4f1.441AO//ED t/A/oeR BU /(.,DiNGS 3, 4,3, 6, 4.i/0 7, VALLEY VIEW ESTATES SITE UTILITY PLAN DeTE.UT /o& 1,/PE NOTE: Proposed Site Utility Improvements Shown are Schematic Only. Plan does not Show All Required French Drains or Foundation and Retaining Wall Drain Lines. A Detailed Utility Plan will be Prepared for Building Permit Application. LEG?E,VD ▪ P OP0..E0 F,QEA/CF/ OK 4 /A/ /A/TEcePTOR TRENCH PROPOSED STORM UA/E • PCOPa3E0 WATE.0 LA/6 FleoFio6E.0 ,64W/TARY EWER L /A/E REALIGNMENT- temporary measures are being taken which will accommodate flows. The plant will be upgraded in 1986 if present plans are implemented. There are no problems shown in the City of Tukwila Comprehensive Sewer Plan. The portion of the plan that shows this area is in Appendix G. Mitigating Measures 1. If water use were reduced by residents implementing water - saving measures in their homes, the volume of sewage that would be discharged from the project area would be also reduced. 2. The realignment of a portion of the existing sewer will require a properly designed and constructed excavation. Water levels will be obtained prior to excavation, the stability of the excavation will be evaluated by the geotechnical engineer with respect to bearing failure and bottom heave due to seepage, a dewatering system will be designed and implemented as necessary, the excavations will be properly stored, and the construction will be undertaken by a contractor thoroughly experienced in this type of work. Unavoidable Adverse Impacts Sewage generated by the development will contribute to above capacity discharges at the Renton Metro Sewage Treatment Plan. The proposed project will increase the demand for long -term city maintenance. Stormwater (Please refer to previous section covering Water). Solid Waste Existing Conditions Businesses and residences in the surrounding area are currently served by Sea -Tac Disposal, which has dumpsters and compactors available for rent. Following collection, solid waste is taken to the King County Transfer Station. Impacts The proposed development will increase demand for solid waste collection which would be provided by Sea -Tac Disposal. Mitigating Measures None. 125 Unavoidable Adverse Impacts None. Aesthetics Existing Conditions The site is currently a wooded, undeveloped hillside, covered primarily with alder. It is situated just southwest of the I -5/405 Interchange and directly west (across I -5) from the Southcenter Shopping Mall. The McMicken Heights residential area is located above the site to the west. (Please refer to Figure 17 Aerial photograph.) Bordering the site on two sides are existing roads - 53rd Avenue S., to the west and Slade Way to the south. The site is visible from the valley floor as part of the wooded valley wall between Interstate 5 and the single family residences along the hillside. The existing view from the site looking east toward I -5 and the Southcenter Shopping Mall is almost entirely blocked by the height and density of the existing vegetation on the site. During the winter, the valley floor is visible through the trees. Impacts The appearance of the site will be converted from wooded open space to a multi- family development, consisting of eighteen 3 -story buildings, parking areas, and landscaped and natural open space. (See Figure 20, Plan View). Sixty -eight percent of the existing vegetation will be removed during construction. The level of activity on the site will increase upon occu- pancy, with 212 new residents in the area The development would be visible to drivers along Slade Way and 53rd Avenue South, although view blockage from 53rd Avenue South would be minimal. Only two buildings on the extreme north and south sides of the site would have rooflines higher than the road grade -- in both cases less than 15 feet above road grade. All other buildings would be below the road grade. View blockage from McMicken Heights, above 53rd Avenue South, looking east toward Southcenter Shopping Mall and I -5 also would be minimal. The proposed multi - family building rooflines are at least 20 feet below finished grade of these residential homes. The proposed development would have its greatest effect on views from the east, including Southcenter Shopping Mall, Tukwila Hill and to a lesser extent, traffic moving southbound on I -5. However, existing vegetation on the east side of the site nearest the freeway will be retained to the extend possible to minimize the visual change to the hillside. Please refer to Figure 18, Conceptual View from Tukwila Hill. Due to a bend in the freeway, views from motorists driving northbound on 1-5 would be only minimally affected. Building exteriors will be mostly natural wood and stucco. Class C com- position shingles will be used on the sloped roofs. Ornamental landscaping will be introduced in the parking areas and adjacent to the buildings to sof- ten the visual impact of the developed areas. 126 SOUTH CENTER SHOPPING MALL INTERSTATE - 5 VALLEY VEW ESTATES 0 m 2 0 01 0 CROSS SECTION m FIGURE 18 OVER - PASS VIEW FROM TUKWILA HIILL LOOKING S.W. (CONCEPTUAL) FIGURE 19 • • 2 a 0 6ZT SLADO WAY 0 2 0 2 B MOS VI lir -9 r 2 .5 CD VALLEY VIEW ESTATES TUKWILA, WA PATE _ .t . — REVISIONS_ Van De Vanter ASSOCIATES LANDSCAPE ARCHITECTURE SUITE 201 / eI2 BELLEVUE WAY NE / BELLEVUE. WA 211004 / 400 .al-eool C) CD N 1 0£T VALLEY VIEW ESTATES TUKWILA, WA SECTIONS Van De Vanter ASSOCIATES LANDSCAPE ARCHITECTURE SUITE 201 / 612 BELLEVUE WAY NE / BELLEVUE. WA 0eoue / (206) 461 -6001 • • • CONCEPTUAL CROSS SECTION •OAL•s 1 1 40' I lim41"7"7 040 40 SO Figure 21 SUITE 201 i 21E BELLEVL! WEE ME / BELL Mitigating Measures 1. Existing vegetation will be maintained to the extent possible along the western portion of the site. 2. Ornamental vegetation will include sycamores along Slade way and along the parking lot. Vine maple and flowering cherry would be interspersed among the buildings. Other plant materials would include platinia, rhodo- dendron, mahonia, viburnum Davidi, ivy and lawn. 3. The landscape plan which is subject to approval by the Board of Architectural Review, could include plant materials, similar in character to existing vegetation on the site. Unavoidable Adverse Impacts The view of a portion of a steep wooded hillside would be replaced with that of a multiple- family residential development. Human Health Existing Conditions The site in its undeveloped state does not pose any special health hazards. However, the site is located adjacent to freeway corridors where high noise levels exist and higher than average concentrations of air pollutants can be expected. The human response to noise has been documented by the Environmental Protection Agency. Continuous noise at high decibels is not only irritating but can cause damage to the hearing mechanism and otherwise impair both phy- sical and mental health. Prolonged noise exceeding 80 decibels (dBA) can result in hearing loss. Noise in excess of 55 dBA can interfere with speech communication, and noise above 35 dBA can disrupt sleep. Other physical effects from continuous, excessively loud noise levels are increases in blood pressure and alterations in heart rate, which are usually temporary but may become chronic. It is improbable that environmental noise itself causes men- tal illness; however, the continual exposure to noise of a person already suffering in a depressed state may promote stress in that person, which can aggravate the condition of mental illness. Carbon monoxide (CO), which is a by- product of internal combustion, accumula- tes in areas of heavy, slowly moving traffic. CO can reduce the oxygen carrying capacity of blood, resulting in drowsiness and loss of vigor. Levels of CO vary significantly by location. In addition to carbon monoxide, automobiles emit two other chemicals, hydro- carbons and nitrogen oxides, which react in the presence of sunlight to pro- duce ozone. This chemical reaction occurs over a period of time, with ozone concentrations highest near major urban areas. Ozone can aggravate the con- ditions associated with asthma and heart and chronic lung disease. Table 2 in the Air Quality section of this FEIS provides the most recent measurements 132 of these three automobile - generated pollutants at monitoring stations nearest the site. However, no monitoring has occurred in the area for several years. Impacts The varying noise levels to which project residents would be exposed are described in detail in the Noise Section of this FEIS. In summary, with the noise mitigation measures currently proposed by the applicant, exterior noise levels outside the fenced play area, including the proposed recreation areas, would be in a range EPA characterizes as having significant adverse impacts (i.e., 65 -70+ d8A's). Continued exposure to these noise levels could be a cause of irritation and stress. Day -night noise levels within the units with windows closed would generally be within EPA's recommended interior noise level (i.e., 45 Ldn or below). However, with windows open, noise levels would substantially exceed the level which EPA deems necessary to protect health and welfare with an adequate margin of safety (i.e., 58 -62 Ldn vs. dBA max vs. threshold of 50 dBA max). Unless forced -air ventilation were provided, these higher levels could be expected when residents found it necessary to open windows for ventilation. Residents to the west and south of the subject site would be the most sen- sitive receptors of construction noise. The highest construction noise levels would be received at a residence at the corner of Slade Way and 54th Avenue South, about 100 feet from the southernmost proposed building. At this distance, construction noise levels could average between 59 and 82 dBA, depending upon the activity and phase of construction. Since existing daytime noise levels from I -5 average about 70 dBA in this area, it is expected that the noisiest activities could exceed existing traffic noise by up to 12 dBA. However, typical construction noise would be close to the levels of existing noise and therefore would be largely masked. Although an increase of 12 dBA over existing noise levels to 82 dBA could be a serious source of annoyance and irritation to area residents, it is not expected to cause significant mental or physical damage given the infrequent and tem- porary duration of such activities. Project residents with existing health problems relative to asthma or heart or lung disease might experience aggravation of the disease due to the higher than average ozone concentrations that are likely to exist in this major urbanized area, near the junction of 1-5 and I -405 and the Southcenter parking lot. The effect of off -site automobile - generated pollution on pro- ject residents would be similar to that experienced by others who reside in the immediate vicinity of the Southcenter Shopping Center. There are no known studies which correlate health problems among residents in this area to their proximity to the freeways or the Southcenter parking area. Mitigating Measures Please refer to the mitigating measures in the Noise and Air sections of this FEIS. 133 Unavoidable Adverse Impacts 1. Project residents using the outdoor recreation areas would be exposed to continuous levels of high noise which are apt to prove irritating and stressful. 2. With building windows open, residents would experience high noise levels characterized by serious speech interference and annoyance and possibly severe sleep disturbance at night. 3. Project residents with existing health conditions related to asthma, and heart or lung disease might experience aggravation of their condition due to the site's proximity to I -5, I -405 and the Southcenter parking lot. Archaeological /Historical Existing Conditions There are no know historical sites or archaeological resources on the site or in the immediate area. Impacts The potential or archaeological resources existing on the site is considered remote. However, the proposed mitigation measure responds to the slight eventuality of such resources being uncovered during construction. Mitigating Measures In the event that archaeological or historical materials are discovered during construction, work in the immediate area will be discontinued and the Office of Archaeology and Historical Preservation will be notified. Unavoidable Adverse Impacts None. Economic Factors Existing Conditions Currently, the undeveloped site is generating a negligible amount of munici- pal revenue through property taxes. There are no direct municipal expen- ditures associated with the site with the exception of minor expenditures such as storm drainage and roadside mowing costs. Impact The proposed development which is estimated to have a property value of $5,021,200 upon completion, would generate approximately $27,107 in municipal revenue annually upon completion. Building and plan check fees would accrue approximately $18,902 prior to development. Other taxing jurisdictions would 134 realize approximately $43,446 per year as a result of the project through property taxes. (Please refer to Appendix F for a detailed fiscal analysis). Total municipal expenditures created by the development are estimated at approximately $54,370. The net affect of the proposed project would be a municipal loss of approxi- mately $27,263 annually of $129 per project resident. As explained below, per capita cost of this development, as is the case with other residential uses within the City, are generally subsidized by revenue generated from com- mercial and industrial development. (Refer to Appendix F). It should be noted that generally residential uses, particularly large lot single family- uses, are not fiscally beneficial to a municipality. Non - residential uses such as commercial and industrial uses are generally profi- table land uses and therefore, subsidize services for residential uses. Thus if fiscal impact studies in themselves were used as the criterion for approving a project, only commercial and industrial uses would be permitted. However, fiscal analyses can be useful in assisting the City plan for distri- bution of future services. Mitigating Measures None. Unavoidable Adverse Impacts City costs would increase to provide needed services. 135 IV UNAVOIDABLE ADVERSE IMPACTS o While the recommendations for earthwork, site drainage and erosion control structures for the project are intended to increase surficial slope stabi- lity, there is always the possibility that localized conditions may vary to the extent that some earth movements might occur during construction, particularly where zones of seepage are encountered. These are antici- pated to be small in nature and are not expected to result in any earth spillage outside of the site limits. o Site alterations during portions of the construction phase may result in temporary slopes somewhat steeper than the final configuration that will be achieved. • Stripping of site vegetation will create the possibility of surface ero- sion due to rainfall and seepage from springs; any potential off -site impact will be controlled by implementation of a City- approved temporary erosion and sedimentation control system. o Increased air pollution from automobile emissions will contribute insigni- ficantly to hydrocarbon levels. o Potential aggravation of existing health problems of project residents relative to asthma, heart or lung disease as a result of the site's loca- tion in the vicinity of Interstate 5 /Interstate 405. • Short term odors during construction. o Removal of all natural vegetation from approximately 68% of the site. • Removal of vegetation will result in the loss of animal habitat. Most species that currently utilize the area proposed for grading and develop- ment will be eliminated. Urban tolerant species will replace those spe- cies which are not. o EPA's "Noise Guidelines for Environmental Impact Statements" indicated interior sound levels would be characterized as having adverse noise impacts when windows are open. o Exterior noise levels on the site would have significant adverse noise impacts if no mitigating measures are provided. • Construction activities will cause temporary noise impacts at the closest adjoining residences. 0 Project owners will be subject to the conditions of a legal non - conforming use. o Project owners may be required to pay for additional insurance or provide collateral other than the residential property to protect the loan insti- tution in case of fire or other loss which amounts to over 50 percent of the replacement cost. 136 o Project owners will be subject to the conditions and requirements of the building permit regarding retaining the geotechnical engineering con- - sultant to 'provide or direct the slope instrumentation and monitoring program during the entire life of the project. o Some residents in vicinity of site which feel a loss in quality of life and neighborhood cohesion. Consumption of building materials and energy. o Approximately 25 percent increase in the left -turn component from Klickitat Drive to 53rd Avenue South. o Potential parking spillover onto 53rd Avenue South, Klickitat Drive or Slade Way due to possible social activity. • Traffic accidents may be, expected to increase in proportion to the increase in traffic volumes on streets surrounding the proposed develop- ment. O There will be an increased demand for fire service. O Increased demand for police service. o Slight increase in demand for an additional classroom at Tyee High School. o The proposed project will increase demand for local park use by approxima- tely eight percent. ° The proposed project will increase the demand for long -term maintenance of City of Tukwila facilities. o Increased energy demand on the site in both the short and long terms. o Short -term impacts on vehicular travel at South 160th Street /53rd Avenue South if trenching is required within the right -of -way or across the road. • Sewage generated by the development will contribute to above capacity discharges at the Renton Metro Sewage Treatment Plan. The proposed pro- ject will increase the demand for long -term City Maintenance. o Replacement of a portion of a steep wooded hillside with a multiple - family residential development. o Short term annoyance and irritation to area residents during construction. Potential aggravation of existing health problems of project residents relative to asthma, heart or lung disease and in reaction to continuous noise at high decibel levels. o Increased demand for services in the project vicinity. 137 V. Short Term Use vs. Long Term Productivity The residential development proposed for the site would be a relatively long- term use of the land, since the buildings, could be expected to remain for at least 50 years. Due to the project's status as a legal, non - conforming use, certain structural alterations that might be desirable over the long -term could be prohibited, for as long as the property remained zoned for single family use. The proposed project would prevent use of the land as open space and would foreclose the possibility of maintaining the hillside as a visual and physi- cal buffer between the freeway and residential areas further to the west. The advisability of placing a multi - family development on this hillside ver- sus retaining the site in open space depends in part upon the adequacy of the mitigation measures implemented to assure long -term slope stability. Given the site's proximity to 1-5, I -405 and the Southcenter Shopping Center, and the general attractiveness of view property, development of the site might well occur whether or not this project is constructed, assuming appropriate mitigation measures could be implemented. Realization of the project would result in economic benefits to private investors as well as short -term payroll for construction workers. IN addi- tion, it would provide new housing opportunities in the City of Tukwila. These benefits must be balanced against the loss of open space and other una- voidable adverse impacts described in Section IV of this FEIS. Development at some future time could involve increased costs because of inflation and the potential scarcity of building materials. Although deferral of development would not necessarily eliminate the environmental impacts associated with this project, any subsequent development proposal would be required to conform with the single family zoning that now applies to the project site. The environmental impacts of a single family develop- ment are compared to those of the proposed action in the Alternatives Section of this FEIS. 138 VI.Irreversible and Irretrievable Commitment of Resources Completion of the proposed action would result in the long -term commitment of most of the 7.08 acre site for buildings, parking lot and landscaped areas, thereby precluding other uses. Due to the longevity and maintenance of structural improvements, land once developed for specific uses seldom reverts to a lower economic use or to its natural state. Thus, the proposed develop- ment would essentially be an irreversible commitment of land resources. Natural resources expended to construct the development would include alumi- num, steel, glass, wood, concrete, sand and gravel. Of these, wood is the only material that is a renewable resource. Some of the other materials are technically recyclable, but for all practical purposes, they would be irretrievable committed to the proposed development. Additional quantities of hydroelectric energy and fossil fuels would be required for space heating and lighting, and other energy needs, over the life of the project. Energy is not a renewable resource; as such, its use for the proposal would prevent it from being put to other uses that may or may not be more desirable environmentally. Likewise, implementation of the proposal would require a commitment of labor and financial resources which could potentially be used for different purposes. Water consumption would increase. Additional long -term commitments of public water, sanitary sewer capacity, solid waste disposal capacity, communication services and police and fire protection services would be required to main- tain the development. However, these services are presently available to the site and the demand for them would be comparable to the demand generated any similar development. 139 VII.Alternatives To The Proposal The SEPA Guidelines provide that "Reasonable alternatives shall include actions that could feasibly attain or approximate a proposal's objectives but at a lower environmental cost or decreased level of environmental degradation." 1. No Development Description: The site would remain in its undeveloped state as part of the wooded valley wall above I -5. Impacts: All adverse environmental impacts of the proposed project would be eliminated. Feasibility: The proponent's primary objective is to construct a multi- family development which would not be achieved by this alternative. It is improbable that the site would remain undeveloped unless it were acquired by the City of Tukwila or King County as a greenbelt or for park use, or unless development of the property were deemed infeasible due to the costs associated with ensuring long -term slope stability. The site is not shown as a park or greenbelt in the Comprehensive Plan nor is it designated for acquisition in the City's capital improvement program. 2. Single Family Development Description: Up to 21 detached dwelling units could be constructed under the current zoning of the property (i.e., under the 1982 Zoning Code). Impacts: Implementation of the single family alternative would have less environmental impacts on most elements of the physical and human environ- ments than the proposed action. This alternative would be compatible with the surrounding single family neighborhood in character, density and scale. The buildings would not be subject to the restrictions of a non- conforming use. Traffic volumes would approximate those of other single family areas and would be roughly 23% less than those generated by the proposed action. Less cut and fill would be required and less of the site would be covered with impervious surface. In general, single family resi- dents would be exposed to the same potential noise and air quality impacts as residents of the proposed condominiums , although under the single family alternative fewer individuals would be affected. The development would be less visible from the valley floor than the proposed multi - family development. Feasibility: The single family development alternative would not meet the proponent's objective of providing a multi - family residential development. The necessary site improvements could price the single family homes higher than their market value. 140 3. Development of a More Intensive Use Description: Under the site's previous R -4 (Low Apartments) and RMH (Multiple Residence High Density) zoning the following uses were poten- tially permitted: R -4 District: Apartment houses, row houses, boarding houses, children's boarding homes, lodging houses, clinic for people only, con- valescent homes, nursing homes, convents, private clubs or fraternal orders, schools other than those permitted in the R -2 District. RMH District: Any use permitted in the RMH District, Apartment House, hotels; offices and clinics provided they do not exceed the first two stories. Based on the listed permitted uses, a development scenario could have included the following: Use Designation Convalescent Home or Apartment Building and Office (2 story) Acres 2.52 @ 300 SF /Patient lot area, or 2.52 @ 30 DU /AC. 2.86 @ 40% Site Coverage Density Yield 350 patients 75 DU's 50,000 s.f. Impacts: Overall, implementation of this alternative would impact both the physical and human environments to a greater degree than that of the proposed action and thus it would not be a reasonable alternative under SEPA. For example, site disturbance would be substantially increased and traffic generation would be roughly double that of the proposal. Feasibility: This alternative would not meet the proponent's objectives nor is it potentially allowed, since a building permit application pur- suant to the site's previous R -4 and RMH zoning was not filed prior to the effective date of the current Zoning Code. 4 Lower Density Multiple Family Development (Variations A and B): Description of Variation A: Under this lower density alternative, five fewer buildings would be constructed providing a total of 13 buildings and 78 dwelling units. Impacts of Variation A: For the most part, adverse environmental impacts would be proportionately less than those created by the proposed action. Site coverage, including the size of the parking lot would be reduced and an additional .5+ acre of undeveloped open space would be preserved. Population on the site would be reduced by approximately 28 %, with the demand on public facilities and services reduced accordingly. Traffic volumes likewise would be reduced by approximately 28 %. 141 Feasibility of Variation A: Construction of five fewer multi- family buildings would meet the proponent's stated objectives for multifamily development, but not at the densities permitted under vested zoning. This alternative might not be economically feasible due to the higher site improvement costs and infrastructure costs per dwelling unit compared to the proposed action. Housing costs would be higher and conceivably, more than their market value. Description of Variation B: Under this lower density alternative, two fewer buildings would be constructed. Specifically, Buildings No. 1 and No. 2 which are proposed for the southwest portion of the site on slopes of 30 -40% would be eliminated. Impacts of Variation B: The buildings in question are located in a steep, uphill area (30 -40% slopes) near the location of the landslide which occurred on the property in 1960 -61 as a result of a borrow pit excava- tion. Elimination of these two buildings would eliminate any potential risks associated with construction in an area of questionable slopes. Otherwise, impacts of this alternative generally would be reduced in pro - portion. to the reduction in density, i.e., two fewer buildings and 12 tewer units. The entire southwest corner of the site would be preserved as open space and the second driveway onto Slade Way would not be required. Feasibility of Variation B: Reduction of the project size from 18 to 16 buildings and 108 to 96 units would achieve the proponent's stated objec- tives for multifamily development, but not at the densities permitted under vested zoning. While this alternative would result in less economic return to the developer than the proposed action, SEPA does not provide that a "reasonable" alternative must provide a desired economic result. Potential loss of income from these units might be partially offset by avoiding the higher site improvement and infrastructure costs that could be associated with developing this portion of the site. 5. Revised Building Design Description: The building design could be revised to mitigate noise impacts on project residents. Specifically, the bedrooms could be located on the west side of the buildings, east - facing decks could be enclosed with glass, and a forced -air ventilation system provided. Impacts: Evening noise impacts on project residents would be reduced with the added distance in walls between the bedrooms and noise generated from 1-5. Forced -air ventilation would eliminate the need to open windows, which would significantly reduce noise within the dwelling units. (Under the proposed action, with windows open, day -night noise levels and night- time maximum noise levels far exceed recommended standards.) Glass enclo- sure of east - facing decks would reduce interior noise and increase the utilization of the decks. The cost per unit for these features would be slightly higher than the cost of the proposed building design which might eliminate some potential buyers who otherwise could afford to reside in the proposed project. All other impacts described in the EIS would remain the same. 142 Feasibility: This alternative meets the proponent's stated objectives. While relocation of the bedrooms and a forced -air ventilation system are design elements that probably would need to be incorporated at an early stage, glass enclosure of the decks could be an option available to prospective buyers. The cost of this option could then be added to the price of the unit. 143 PART TWO COMMENTS AND RESPONSES REPLY TO ATTENTION OF Planning Branch DEPARTMENT OF THE ARMY SEATTLE DISTRICT, CORPS OF ENGINEERS P.O. BOX C -3755 SEATTLE, WASHINGTON 98124 JAN 2 8 1985 Bradley Collins, Director City of Tukwila Planning Department City Hall 6200 Southcenter Boulevard Tukwila, Washington 98188 Dear Mr. Collins: We have reviewed the draft environmental impact statement (EIS) for Valley View Estates, Tukwila, Washington. With respect to the U.S. Army Corps of Engineers areas of responsibility for flood control, navigation, and regulatory functions, we do not have any comments. We do have some concerns regarding the proposed project and offer the following general comments. a. The geotechnical report appended to the draft EIS concludes that ". . . development of the property as planned is feasible . . . ." We have no disagreement with this statment, and we are in general agreement with all of the technical recom- mendations given. However, we believe that there is a question of whether or not development of homesites on this landslide - prone site is advisable. In our experience, control of landslides is an inexact and difficult task, and it often takes many years before a slide will completely react to changes such as vegetation removal, regrading, and installation or deterioration of drainage facilities. We are concerned that, if instability occurs at some future time, the developers will be gone, and the individual homeowners will find themselves in an unforseen, and possibly very expensive controversy. b. As stated in the report, the long -term stability of the site is dependent upon existing deep- drainage facilities which were installed by, and are apparently maintained by, the State of Washington. There appears to be no clear -cut agreement with the State regarding responsibility for this drainage system. This could result in serious disagreements later on. If sliding even- tually occurs again, or is eminent due to rising piezometric levels, how will responsibility be determined? Is it due to deterioration of the State's drainage system, or due to increased infiltration from vegetation loss and regrading of the site? Who 145 -2- is responsible for remedial measures and /or drainage? This seems to us to be a very serious question which should be answered by formal agreement between the developer and the State of Washington. c. In our opinion there should be a clearly stated commit- ment by the developer that piezometric levels and slope movements will be monitored and evaluated throughout the entire life of the proposed project by a qualified geotechnical engineer who is familiar with the project. Thank you for the opportunity to review,this statement. If you have any questions regarding our comments, please contact Mr. Steven F. Dice of my staff at the above address or by telephone (206) 764 -3624. 9'J 146 Sincerely, GEORGE W. PLOUDRE, P.E. Asst Chief, Engineering Division Response to comments made by George W. Plandre, P.E., Assistant Chief, Engineering Division, Department of the Army, Corps of Engineers 1. GeoEngineers, Inc. has issued a revised Geotechnical and Hydrological report (Appendix A) and the text of the FEIS has been updated to better identify existing conditions and include general requirements for (i) monitoring of soil and groundwater conditions; (ii) maintenance of existing and proposed facilities; and (iii) posting of bonds by the developer to provide the funds for necessary mitigating measures. Refer to revised Earth Resources discussion in the FEIS. 2. See response to 1, above. 3. See response to 1, above. 147 ' )( )FIN SPELL,MAN STATE ( )F WASHINC,T( )N DEPARTMENT OF TRANSPOR FATION ( 1)i+Irik1.-1'(6niniaraIor. • I)- 1. ()-1i.1 S() (--;;/..) li) • January 28, 1985 Brad Collins, Planning Director City of Tukwila Planning Department 6200 Southcenter Boulevard Tukwila, Washington 98188 SR 5, Milepost 154.40 Valley View Estates City of Tukwila DEIS K -542 Dear Mr. Collins: This Department has completed its review of your Valley View Estates Draft Environmental Impact Statement for the construction of 18 condominium buildings totaling 108 units. The following concerns must be addressed in the Final Environmental Impact Statement: 1) Existing traffic volumes, Page 101, volumes for state highways thah our of SR 405 is 136,880 (not 110,000), 112,000). SR 405 volume is 101,180 71,000 (not 67,400). Figure 11 shows substantially lower 1984 ramp counts. SR 5 volume south SR 5 north of SR 405 is 152,000 (not (not 82,000) and SR 518 volume is 2) The traffic generated by this development is substantially low in itself, yet the freeway system in this area generally operates at a low level of service, especially SR 405 during peak hours. Policy 7 on Page 45 states that abutting properties to the development are undeveloped. An analysis of the cumulative impact of development in this area needs to be done in order to develop an equitable mitigation plan for all public services in the area. This is especially critical for transportation since the existing system is operating at capacity. Thank you for this opportunity to review this proposal. We look forward to working with the city and the city to resolve our mutual transportation con- cerns. If you have any questions, please contact Pat Leavy of my staff at 233 -2416. BV:jcw cc: Traffic Design 149 R.F. JOHNSON, P.E. District Design Engineer Response to comments made by R. F. Johnson, P.E. District Design Engineer, Washington State Department of Transportation 1. Comment acknowledged. At the time the traffic study was underway, estimates of existing volumes were made from previous count data. The change in State highway traffic volumes for existing conditions would have no impact on the conclusions reached by the TRANSPO Group in the traffic analysis for this project. The percent of project contribution to total traffic volumes on these highways would decrease as a result of this update. 2. It is acknowledged that the existing highway system is typically operating at capacity during peak commute periods. Generally, cumulative impact discussions in the EIS cover impacts associated with known or proposed pro- jects in a study area. Impacts associated with undeveloped nearby property with no specific development plans are more properly addressed in a more comprehensive transportation plan. Considering the minor impact to the State highways as a result of project - generated traffic, an analysis of potential cumulative traffic impacts assuming development of all local unde- veloped properties is beyond the scope of this EIS. The additional traffic added to the State highway system by this project would generally fall within the day -to -day fluctuations in traffic volume expected with or without this project, and thus be unnoticeable to the average observer on these roadways. 150 It )1 IN `11 I 1 •• .STATE (1F \1\SHINCT( )N DEPARTMENT OF TRANSPORTATION t ,1 I )ntri( 1 .- 1(Inr:ni >tratur • 1)- I. 1,4./ I (..or>nn Ave. Srr., (2-81410 • tie.ullt.. VV 1'/1 ngi n')ti 108 Mr. Rick Beemer City of Tukwila 6200 Southcenter Boulevard Tukwila, Washington 98188 March 19, 1985 SR 5 MP 154.0 Valley View Estates Dear Mr. Beemer: The Department of Transportation has reviewed the noted project. We wish the following comments be addressed or identified: 1. Possible changes in the ground water table or subsurface flows that may affect the Department of Transportation is retaining walls or slope stability. 2. Possible changes of surface water runoff rates and potential impacts on downstream facilities. If the downstream systems are inadequate due to increased flows attributable to this development, proposed methods of mitigating impacts. This could include developer funding the necessary improvements as mitigation measures. 3. Identify impacts the proposed construction would have on Department of Transportation facilities. Of utmost importance is the continuous monitoring of slope stability and ground water levels prior to, during and after construction. The duration must be identified due to the areas acute sensitivity to movement and the potentially high degree of damage if movement occurs. 4. Assurance the proposed construction will not affect slope stability. If conditions are imposed, what are they and the risks involved. 5. The Department of Transportation cannot be responsible for actions taken by others outside our right -of -way. If such actions result in increased instability for an area now considered stable, corrective action must be the responsibility of others. In answer to your questions regarding maintenance of the Department of Transportation's drainages, we are responsible for normal maintenance. The Department of Transportation is also responsible for replacement of drainage systems that are inoperative or worn out within our right -of -way. The Department of Transportation is not maintaining the wells per se. We are flushing the horizontal drains that were installed to tap into the individual wells. This does not include replacement of drainage facilities that are functional and become non - functional due to impacts by off site development. I trust the above information answers your concerns as indicated in our last meeting. If you have any questions, please contact me at 233 -2306. Sincerely, 151 R. F. g6HNSON, P. E. RFJ /hl District Design Engineer I )UANI: I1I.REN P- )N Lo( rel.(ry 1 1 2 3 4 5 MEM MAR 21 1985 CITY OF TUKWILA PLANNING DEPT. Response to comments made by R. F. Johnson, P.E. District Design Engineer, Washington State Department of Transportation 1. The Earth and Water sections of the FEIS and /or the GeoEngineers, Inc. geotechnical /hydrological report (Appendix A) has generally been modified to adequately include and address the concerns raised by this comment on the DEIS. 2. The EIS has been updated to better identify stormwater discharges, flow paths, and the off -site properties that are expected to receive these discharges. The revised discussion of existing site drainage conditions, impacts, and proposed mitigative measures are presented in the FEIS section under "Water" entitled "Surface Water Movement, Quantity, Quality, Runoff /Absorption." 3. Refer to response number one. 4. Refer to response number one. 5. GeoEngineers, Inc. has issued a revised geotechnical /hydrological report (Appendix A) and the text of the FEIS has been updated to better identify existing conditions and include general requirements for (i) monitoring of soil and groundwater conditions; (ii) maintenance of existing and proposed facilities; and (iii) posting of bonds by the developer, to provide the funds for necessary mitigating measures. Refer to the revised Earth Resources discussion in the FEIS. 152 ")HN SPELLMAN`' Governor STATE OF WASHINGTON DEPARTMENT OF ECOLOGY • Mail Slop F'V.1 • Olympia, Washington 98504 • (206) 459 -6000 January 15, 1985 Mr. Brad Collins City of Tukwila Planning Department 6200 Southcenter Boulevard Tukwila, WA 98188 Dear Mr. Collins: DONALD W. MOOS • Director CITE' C. i:....,_A Thank you for the opportunity to comment on the draft environmental impact statement for the Valley View Estates. We reviewed the EIS and have the following comment. The Renton Sewage Treatment Plant (STP) is currently operating above design capacity much of the time and it will be several years before it is ex- panded. There is no guarantee that sewer service will be available at the time desired for this development. If the treatment plant continues to operate well and meets the required effluent limits until the expanded facilities are operating, no restrictions will be placed on sewer connections or extensions. If you have any questions, please call the Northwest Regional Office at (206) 885 -1900. BJR:pk 153 Sincerely, Barbara J. Ritchie Environmental Review Section i Response to comments made by Barbara J. Ritchie, Environmental Review Section, Department of Ecology 1. Comment acknowledged. See the revised Sewer discussion in the FEIS. 154 JOHN SPELLMAN Governor STATE OF WASHINGTON JACOB THOMAS Director OFFICE OF ARCHAEOLOGY AND HISTORIC PRESERVA_..___._...- I 1 1 I West Twenty -First Avenue, kL -11 • Olympia, Washington 98504 • ("J'' >'5, 1-.p `i ! !A) Mr. Brad Collins Planning Director Tukwila Planning Department 6200 Southcenter Blvd. Tukwila, WA 98188 Dear Mr. Collins: J �t r. J .► r. i r� 7 i., 1 January 8, 1985 Log Reference: 601- C -KI -05 Re: Valley View Estates A staff review has been completed of your draft environmental .impact statement. In the event that archaeological or cultural materials are discovered during project activities, work in the immediate vicinity should be discontinued and this office notified. Thank you for this opportunity to comment. Sincerely, dw Robert G. Whitlam, Ph.D. State Archaeologist (206) 753 -4405 155 Response to comments made by Robert G. Whittam, Ph.D., State Archaeologist, Washington State Office of Archaeology and Historic Preservation - No response required 156 King County Executive Randy Revelle Department of Planning and Community Development Holly Miller, Director • L, January 25, 1985 T0: Ralph Colby, Supervisor, Plan Implementation Building and Land Development Division FM: Harold Robertson, Manager RE: DEIS Review of Valley VieVEstates We have reviewed the above Draft EIS and have the following contents: Relationship to Existing Laws, Policies, and Plans; page 26: Since the subject property is adjacent to the Highline Plan area of unincorporated King County, the FEIS should state haw this proposal relates to the King County Comprehensive Plan and the Highline Com - munity Plan. Surface Water Control; pages 70 -76: The DEIS clearly points out the critical relationship between the pro- posed on -site drainage system and the drainage system built by the Department of Trasnportation (DOT) during the 1 -5 freeway construction. The final EIS should discuss more specifically how the City intends to ensure adequate maintenance of the State's deep drainage facilities. For example, will an interlocal agreement with DOT be pursued? The final EIS should also address the issue of and responsibility for re- placing the I -5 drainage system. The Geotechnical /Hydrological Studies in Appendix A conclude that the effectiveness of the freeway drainage system will slowly deteriorate over a period of years, even with accept- able levels of maintenance, requiring additional drainage improvements. The DEIS notes in several places that the stormwater detention system will be designed to accommodate a 10 year storm, with flows in excess of that discharged through an emergency overflow to an unspecified location off -site. The FEIS should identify the off -site properties ex- pected to receive these excess storm water discharges and the impacts/ mitigation measures proposed. Water Service, page 129: The FEIS should address the alternatives to the City providing water service to the project in the event a service area agreement between Water District 75, Seattle and Tukiiia:cannot._be_ consummated. 157 Planning Division 700 Alaska Building 618 Second Avenue Seattle, Washington 98104 (206) 344.7610 Ralph Colby January 25, 1985 Page Two Impacts on the project fran alternative water service arrangements should also be specified. The FEIS should also discuss the potential for cross-connection_prob-- lems with sewer and water service facilities criss-crossing one another on the site. Non- Conforming Uses, page 50: The FEIS should more clearly identify the responsibility the City in- tends to require of the property owner concerning the public's know- ledge of the non - conforming status of the project. How will the pub- lic's right- to-know be protected concerning the owner /purchaser re- sponsibilities in.the event the project or parts of the project require reconstruction or rebuilding? Transportation, page 98 -116: The DEIS states 34 percent of daily trips and 39 percent of evening peak hour trips will use Klickitat Drive eastbound. The traffic impact of these trips on Klickitat Drive and Klickitat Drive /Southoenter Parkway intersection should be addressed, along with possible mitigation measures. HR:VN:awm cc:. Lois Schwennesen, Chief, Community Planning Section ATTN: Vaughan Norris, Community Planner Martin Seybold, Chief, Resource Planning Section ATTN: David Clark, Resource Planner B'Young Ahn, Chief, Transportation Planning Section ATTN: David Gualtieri, Transportation Planner 158 Response to comments made by Harold Robertson, Manager King County Department of Planning and Community Development 1. See the revised Plans and Policies section of the FEIS. 2. GeoEngineers, Inc. has issued a revised Geotechnical and Hydrological report (Appendix A) and the text of the. FEIS has been updated to better identify existing conditions and include general requirements for (i) monitoring of soil and groundwater conditions; (ii) maintenance of existing and proposed facilities; and (iii) posting of bonds by the developer to provide the funds for necessary mitigating measures. Refer to revised Earth Resources discussion in the FEIS. 3. The EIS has been updated to better identify storm water discharges, flow paths, and the offsite properties that are expected to receive these discharges. The revised discussion of existing site drainage conditions, impacts, and proposed mitigative measures are presented in the section under "water" entitled "Surface Water Movement, Quantity, Quality, Runoff /Absorption in the FEIS. 4. The current proposal is for Water District No. 75 to provide water service to the project instead of the City of Tukwila since the project site is within District No. 75's service area. The City of Tukwila Public Works Department will require that on -site utili- ties are installed with proper separations to preclude the possibility of any cross - connection problems. 5. As indicated in the Land Use section of the FEIS, the City proposes to require that prospective purchasers (assuming the development is sold as condominiums) are advised of the buildings' non - conforming status. One possible method of notification would be a requirement that the condominium covenants disclose not only the non - conforming status of the buildings but also the specific zoning restrictions that apply to such uses. The language used in the covenants could be made subject to City approval. However, as acknowledged in the FEIS, it would be difficult for the City to enforce a requirement that all prospective purchasers are made aware of this infor- mation. 6. The DEIS and FEIS do state that 34 percent of the daily and 39 percent of the evening peak hour trips will use Klickitat Drive east of 53rd Avenue. Figure 6 showing project - generated traffic volumes and Figure 7 showing forecasted 1987 traffic volumes with and without the proposed project indi- cate that this reflects 35 peak hour and 310 daily trips in both directions. Of the 35 evening peak hour trips on this leg, about 25 would be project - generated inbound trips attempting to make left turns during this one hour period. As indicated on page 20 of Appendix E, the additional 25 vehicle demand for left turns in the evening peak hour would not change the overall average operating level of service for this movement compared to forecasted 1987 conditions without the project. Level of service (LOS) D operations would exist with or without the project. Sporadic backups of this left -turn movement would increase about two to three vehicles at any given point in 159 time within the evening peak period without project traffic; project traffic would not likely result in noticeable differences to this condition. Page 24 of Appendix E indicates that mitigation was suggested to reduce the delay to through vehicles on Klickitat Drive due to delayed left- turning vehicles. Installation of a left -turn pocket as described on page 24 of. Appendix E would reduce the potential for rear -end accidents associated with through vehicles conflicting with left -turn vehicles. As indicated, this suggested improvement would generally be equally desirable with or without construc- tion of this project. At Southcenter Parkway /Klickitat Drive, traffic volumes on both a daily and peak hour basis would increase about one percent due to the project, and thus project impacts would be unnoticeable. No improvements are currently scheduled on,the City 6 -Year TIP; no additional improvement needs would be triggered by traffic from this project. 160 BOB ROEGNER, MAYOR PAT DUGAN, PLANNING DIRECTOR January 24, 1985 Bradley J. Collins, Director of Planning City of Tukwila 6200 Southcenter Boulevard Tukwila, WA. 98188 RE: Draft EIS for Valley View Estates Dear Brad: PLANNING AND COMMUNITY DEVELOPMENT DEPT. 25 WEST MAIN, AUBURN, WA 98001 (206) 931- -3090 Ref. No. 85 -036 The City of Auburn appreciates the opportunity to review the above - referenced document. However, we have no concerns or comments regarding this proposal or the draft EIS. Thank you again for including us on the distribution list. Sincerely, Department of Planning &\ Cmmun i ty Development V? c Val Batey Associate Planner VB :pb 161 Response to comments made by Val Batey, Associate Planner City of Auburn, Department of Planning and Community Development - No response required - SERVING: KING COUNTY 200 West Mercer St. P.O. Box 9963 Seattle. 98109 (208) 344 -7330 KITSAP COUNTY Dial Operator for Toll Free Number Zenith 8385 Bainbridge Island Residents Dial 344 -7330 PIERCE COUNTY 213 Hess Building Tacoma, 98402 (208) 383 -5851 ISNOHOMISH COUNTY 1- 800 -552 -3585 BOARD OF DIRECTORS CHAIRMAN: Harvey S. Poll. Member at Large; IRay Aardal, Commissioner Kitaap County; Randy Revelle, King County Executive: PUGET SOUND AIR POLLUTION CONTROL AGENCY Mr. Brad Collins, Planning Director Planning Department City of Tukwila City Hall 6200 Southcenter Blvd. Tukwila, WA 98188 Dear Mr. Collins: 200 West Mercer Street, Room 205, P.O. Box 9863 Seattle, Washington 98109 (206) 344 -7330 January 28, 1985 Valley View Estates This agency has no comments to submit on the above - titled draft environmental impact statement. Thank you for circulating it for our comments. Sincerely, (CI 4/MAIL- Arthur R. Dammkoehler Air Pollution Control Officer lk 163 Bruce Agnew, Councilman Snohomish County; Charles Royer, Mayor Seattle; Morrie Dawkins, Mayor Bremerton; Doug Sutherland, Mayor Tacoma; VICE CHAIRMAN: Joe Stortini, Councilman for Booth Gardner, Pierce County Executive William E. Moore. Mayor Everett; A.R. Dammkoehler, Air Pollution Control Officer Response to comments made by Arthur R. Dammkoehler, Air Pollution Control Officer, Puget Sound Air Pollution Control Authority; - No response required - 164 jmETRD h' Po Municipali of Metropolitan Seattle Exchange Bldg. • 821 Second Ave., Seattle, Washington January 24, 1985 Bradley J. Collins, Planning Director City of Tukwila Planning Department City Hall 6200 Southcenter Blvd. Tukwila, Washington 98188 Draft Environmental, Impact Statement Valley View Estates Dear Mr. Collins: Metro staff has reviewed this document and offers the following comments. Wastewater Facilities We note the proposal is within Metro's Renton Treatment Plant service area. Metro has prepared a facilities plan for the Renton system with a grant from DOE and EPA, in part because the Renton Treatment Plant has reached its "design" capacity and continued development is occurring within the service area. A final plan for the Renton service area was adopted by the Metro Council in November of 1981 and contains a recommended program for upgrading the Renton system so that water quality and health will continue to be protected. The plan was amended on April 5, 1984 to revise the alignment for the effluent transfer system pipeline. These improvements will be on line in early 1987. In addition, we would like to call your attention to the "existing conditions" section of the EIS regarding sewer facilities (page 132). The 12 inch cast iron sewage main that runs through the site connects to Metro through the Hat Highlands ^ extension (not Val -Vue). Sewage from the site would then be L transmitted to the plant via the Freeway interceptor, Val -Vue outfall and Tukwila interceptor. These corrections should be reflected in the FEIS for the proposed project. Public Transportation The developer has expressed a willingness to work with Metro to ensure that transit patrons from the project will have safe access to transit service. Chuck Gehrts, a Metro transit planner who is familiar with bus zone location and space, can provide assistance regarding this matter. He can be reached at 447 -6367. 165 3 B. Collins January 24, 1985 There appear to be two possible options to consider to assure access to transit service. One could be to provide access through the development to the present bus zones by providing a 3 walking path to 160th Avenue S. The other option is to consider possible relocation of the zones onto 53rd Avenue S. near the project. Mr. Gehrts can assist in determining which may be more practical. Thank you for the opportunity to review and comment. Very truly yours, ie_<„,„/„) a Ruth A. Hertz, Actin`' Manager Environmental Planning Division RAH :lda cc: Chuck Gehrts 166 2 Response to comments made by Ruth A. Hertz, Acting Manager, Environmental Planning Division, Metro 1. See revised Sewer discussion in the FEIS. 2. See revised Sewer Discussion in the FEIS. 3. Comment acknowledged. The developer is receptive to consideration of, but has not committed to, either program. 167 JERRY P. HARRIS, President GEORGE BLOMBERG, Secretary DAN CALDWELL, Commissioner Water altrict Vo. 75, County Telephone 824.0375 January 4, 1985 KEN E. HALL Administrative Manager MARION HARTER Office Manager P.O. Box 68100, Riverton Heights Station Office: 19863 28th Avenue So. SEATTLE, WASHINGTON 98188 Mr. Brad Collins, Planning Director City of Tukwila Planning Department 6200 Southcenter Boulevard Tukwila, Washington 98188 R. W. Thorpe & Associates 815 Seattle Tower Third & University Seattle, Washington 98101 Re: Draft EIS, Valley View Estates 1984 Gentlemen: pi /INNING Water District No. 75 finds it highly impractical in view of the newly - passed Water System Coordination Act for the City of Tukwila to extend a dead end main into our corporate boundary to serve property where the District has existing facilities. Our Comprehensive Plan contemplates looping our existing system from Slade Way along 54th Avenue South to connect to an existing line on S. 166th Street. We are not anxious to continue the flushing programs necessary for the existing dead end mains. Another dead end main installed using City of Tukwila facilities will only contribute to an existing bad situation. The District feels it may also be appropriate to discuss with Tukwila an intertie at the PRV facility on 53rd Avenue South. We do not.desire this potential customer to withdraw from our corporate boundary, nor are we interested in a service area agreement to allow Tukwila to serve a customer we are better equipped to serve. 169 1 City of Tukwila Planning Department and R. W. Thorpe & Associates Page 2 January 4, 1985. We would be more than happy to discuss this project with the City of Tukwila Planning Department or the developer at their convenience. Please call Duane Huskey or myself should you have any questions. Sincerely, Ken Hall Administrative Manager KH:tmw cc: Dr. Herman Allenbach Puget Western, Inc. Paula Russell, Boundary Review Board 170 Response to comments made by Ken Hall, Administrative Manager Water District No. 75 1. Since issuance of the Draft EIS, it has been determined that water service to the project will be provided by Water District No. 75 and not the City of Tukwila. The City of Tukwila Public Works Department is willing to discuss a possible intertie at the pressure reducing station on 53rd Avenue South. 171 Seattle Water Department Kenneth M. Lowthian, Superintendent Charles Royer, Mayor January 23, 1985 Bradley J. Collins, Planning Director City of Tukwila 6200 Southcenter Boulevard Tukwila, WA 98188 Re: DEIS Valley View Estates Dear Mr. Collins: The Seattle Water Department has reviewed the report and we have difficulty in determining the proposed Northerly access to Valley View Estates in relation to our 60 inch major supply line (CRPL #4) which is located on the northern edge of the property in a thirty foot right of way. That right of way is not shown in any figures and the pipeline is mentioned only once on page 131, and not in the context of providing protection. No mention is made of drainage flow in the north portion of the property but figure 6 indicates that the slope would naturally drain a portion toward the right of way. We are concerned about the integrity of the large pipeline and we want assurance the drainage is properly controlled in that area. The report by Geoengineers Inc. in Appendix A, page 11, stresses the key element of site grading will be the collection and control of surface runoff and near - surface seepage. As you state a water service agreement is necessary to transfer to the City of Tukwila service from Water District #75, along with amendments to the Water Purveyor contracts with Seattle. Any questions should be directed to Harry L. Pratt, at 625 -4125. We appreciate the opportunity to review the DEIS. Sincerely, KENNETH M. LOWTHIAN Superintendent of Water KML:poe 173 Seattle Water Department— Exchange Building, 11th Floor 821 Second Avenue, Seattle, Washington 98104 Response to comments made by Kenneth M. Lowthian, Superintendent of Water City of Seattle Water Department 1. See revised Figure 16, Site Utility Plan, in the FEIS. 2. As noted in the revised Utilities section, storm drainage facilities will be included in the project to protect the Water Department's 60 -inch pipeline from adverse drainage conditions. 3. Comment acknowledged. 174 COMMISSIONERS: B. W. BUTTERS BETTY LUNZ MICHAEL J. WEST ar. vuF SEWER DISTRICT 14816 MILITARY ROAD SOUTH P.O. BOX 68063 SEATTLE, WASHINGTON 98168 TELEPHONE: 242-3236 January 23, 1985 Brad Collins, Planning Director City of Tukwila Planning Department 6200 Southcenter Boulevard Tukwila, Wa. 98188 COMMENT ON VALLEY VIEW ESTATES DRAFT EIS SUBJECT: Sanitary Sewers MANAGER: T. J. MATELICH The comments made herein are in reference to the 12" sanitary sewer line owned and operated by the Val Vue Sewer District that traverses the proposed Valley View Estate site. The District and its consulting engin- eering firm, Yoshida, Inc., has reviewed the Draft EIS and the easement for the District's sewer line and has concluded that to case the sewer in those areas where buildings are to be built over the sewer may not be the best method or the most cost effective. Attached is a copy of the site utility plan (Figure 16) on page 130. The District's recommended method is to relocate a portion of the existing 12' sewer line. This is indicated in orange on the revised site utility plan: The relocation will eliminate the potential violation of the City's policy that prohibits placement of buildings on top of sewer lines. It will also eliminate the potential of a possible sewerage spill that could occur during the encasement of the sewer line. The relocation construction of the sewer line can occur without any disruption of service in the existing line. Should any further information or elaboration be required on this matter, please contact this office. TJM /gbs 175 Enc. Sincerely, VAL VUE SEWER DISTRICT J. MATELICH anager /c %/ --- —S1 / EXISTING STORM -1 -� EXISTING STORM SYSTEM & EASEMENT P, J3�• Rono s �r CONTROL MH O\'\ / o c).) VALLEY VIEW ESTATES .\\c) SITE UTILITY PLAN �-C-*\ 5 FIGURE 16 EXISTING SEWER & EASEMENi LEGEND egglimmIPROPOSED STORM LINE V■VI\10ROPOSED WATER LINE ■ ■ ■ ■PROPOSED SANITARY SEWER LINE ■ Response to comments made by T. S. Matelich, Manager Val -Vue Sewer District 1. Portions of the existing 12 -inch cast iron main will be relocated in the revised development so that it will not be underneath proposed building locations, as shown on the site utility plan on Figure 16. The realignment traverses the hillside higher upslope, resulting in a maximum excavation depth of approximately 20 feet. The maximum depth of excavation for the existing sewer line in this area was on the order of 15 feet. In the opi- nion of GeoEngineers, Inc., the proposed realignment of the sewer is feasible provided that the excavation is properly designed and constructed (refer to the October 16, 1985, letter from GeoEngineers, Inc., presented in appendix A of the EIS). The Final EIS has also been revised to discuss these project changes. 177 CARL P. JENSEN STEPHEN R. BLACK JENSEN & BLACK, P. S. ATTORNEYS AT LAW 1401 PACIFIC BUILDING SEATTLE, WASHINGTON 98104 January 25, 1985 Mr. Bradley Collins Planning Director 6200 Southcenter Parkway Tukwila, Washington 98188 (206) 292 -9953 . RE: Herman M. Allenbach Application to Build Valley View Estates Condominiums Dear Sir: The undersigned has been retained by the Tukwila McMicken Action Committee to register so far as possible at this point the objections of this committee to the proposed condominiums as noted above. The principal concerns at this point are the safety of the project as relates to the stability of the property upon which these condominiums are to be constructed and questions of traffic safety for both vehicular and pedestrian traffic. The first concern is a matter of safety and concerns itself with the stability of of the property upon which the proposed units are to be constructed. A review of the prior history of this matter indicates that at the time, of the construction of Interstate 5 which passes along the foot of this rather steep slope, two soil studies were done; one by Dames and Moore and the other by Shannon & Wilson and pursuant to the recommendations in these reports, certain efforts were undertaken by the State Department of Transportion to stabilize this hillside. These matters occurred in the early 1960's. As part of the construction of I -5, the state pursuant to these reports installed pumping stations at the bottom of the hill and weep pipes at various places throughout the side hill, in order to reduce the instability caused by the ever present water in this hillside. Currently evidence indicates that the pumps originally installed by the state have now been removed and the weep pipes 179 Mr. Bradley Collins January 25, 1985 Page Two are either in a state of collapse or are being filled by material which is being moved into these pipes from the surrounding area, obviously by water. The topography of this site indicates that the whole property and probably the entire hillside is located on a slip plain, which with the presence of water and sufficient pressure, can slip at any time. Since the presence of water is given in this case, that which may cause the hillside to further slip would be the weight added by the buildings to be constructed by the proponent, which also has the added effect of making the water problem much worse by covering the ground with buildings which are impermeable. The draft EIS literally assumes that the state will continue to maintain the system presently installed but does not treat the present existing fact that the pumps have been removed, that the state is no longer pumping and that the weep pipes are either collapsing and /or becoming filled with material and accordingly, this system has been permitted to deteriorate by the state itself. This problem must be more specifically addressed by the proponents before any action is taken. It should also be obvious to the governing officials of the City of Tukwila that if any slide did occur, it would not only cause severe property damage to the surrounding homes, but also has the potential of not only property damage, but'injury and death to those people who reside not only in existing residences but also to those who might occupy these condominiums. Needless to say, liability in this instance could be astro- nomical and since the developer will presumably have built and • sold his condominiums, he might not be able to respond in damages for that which occurs and if it were sought to impose damages on the owners of the units, they in all probability would not be able to respond in damages both because one of their major assets, i.e., the condominium would probably have been destroyed. Accordingly, the only party left that has permitted this building to take place with its obvious dangers, would be the City of Tukwila and we would suggest that on this basis alone unless the proponent can somehow indemnify the City of Tukwila on a realistic basis, this application for a permit should be denied. 180 Mr. Bradley Collins January 25, 1985 Page Three Again, the EIS does not purport to treat the problem except to hand it to the State of Washington who is clearly only interested in the stability of I -5, so the problem is basically the City's problem. This letter is intended not only as a comment on the current application and the draft in EIS, but it is also intended to place the City of Tukwila on notice of the potential existence of substantial damage claims because of the obvious dangers inherent in this situation. The second concern has to do with traffic and roads and the safety of children who might occupy Valley View Estates. And also, children and families who reside in the surrounding area will feel the effects of increased traffic. Within the Valley View Estates themselves, no sidewalks are planned except from parking areas to the units and therefore any person in a pedestrian class will be walking, on the streets and driveways of the development and which is a definite safety hazard to pedestrians. Of more serious concern as to pedestrians would be those who would utilize South 160th Street and its extension to 53rd Avenue South as a means of access to school buses on 51st Avenue South. School children would be utilizing this street and its extension to get to school buses on 51st Avenue South and vehicular and pedestrian traffic would be using 160th to go to the stores and parks and schools and other activities to the west. At the present time, the extension of South 160th Street is narrow, it has no sidewalks and at some areas, the beam is less than two feet wide and accordingliy sidewalks cannot be constructed in this street without narrowing the driveway or adding fill in order to build out over the steep slopes. Since in this area it is also true that South 160th Street does not have sidewalks and is a two -lane street, the problem of traffic safety, and safety to all who might attempt to walk this street, imposes a clear and present danger which is nowhere addressed in the draft EIS. One other matter at least needs to be mentioned at this time and that is that the draft EIS envisions that units will be built and sold as condominiums and will be occupied by their owners. This is an assumption which is not borne out by the experience with any condominium, since during the sales period, the developer frequently rents units until their are sold which might take several years and nowhere is there any requirement in the law 181 Mr. Bradley Collins January 25, 1985 Page Four that an owner of property has to occupy his own property. Accord- ingly, the assumption of owner /occupancy of condominiums is simply not valid and it is very likely that some or all of the units would be occupied by tenants. This of course changes the character of the entire project and the EIS does not approach this problem at all. This letter could go on and detail other items such as the obvious increase in vehicular traffic along 53rd, Klickitat Drive and pedestrian traffic as well to Southcenter via Klickitat Drive which has no sidewalks but we believe that the principal concerns have been addressed above. It is submitted that based upon what has been set forth herein, unless the project is substantially redesigned and some provision made both in construction and either by a permanent insurance policy provided by the developer to protect the City of Tukwila and the residents, so that the City can respond in monetary damages should this horrible need arise, and unless these traffic and safety problems are similarly addressed and solved, that this building permit should be denied. CPJ:jg cc: Richard Goe 182 Very truly yours, JENSEN & BLACK, P.S. 4 Response to comments made by Carl P. Jensen Law Firm of Jensen & Black 1. The "Maintenance" sections of the EIS have been updated to include main- tenance of existing and proposed drainage facilities during and after construction. 2. The EIS has been upgraded to include the requirement that the City of Tukwila, its officers, employees, and agents be indemnified from all claims, damages, losses, or liabilities arising directly or indirectly from any earth movement on the site. The EIS also has been revised to include general statements regarding (i) bonds required of the developer and project owners, and (ii) requirements for covenants on the property deeds. 3. Comment generally acknowledged. Pedestrians desiring to access off -site locations will generally walk on or adjacent to the on -site development cir- culation aisle. While the potential for conflict between pedestrians and autos inherently exist in any similar situation, the relatively low amount of total site - generated traffic coupled with the limited off -site pedestrian opportunities would not generally be expected to create substantial adverse impacts. Since parking is allowed on both sides of the circulation aisle, in most instances speeds of traffic on -site would generally be low. To help ensure that on -site speeds are kept to a minimum, it is suggested that speed bumps be installed at appropriate intervals (no closer than one very 200 feet) to help control traffic speeds. To ensure that school children have the opportunity to ingress /egress the site separated from project traffic, it is suggested that a gravel path or sidewalk be included along the east edge of the main parking /circulation aisle from Slade Way on the south to the driveway neck near 53rd Avenue South to the north, where a crosswalk could be provided to access the south edge of the driveway. It is acknowledged that children accessing the school bus stop on 51st Avenue South could be required to utilize South 160th Street between 53rd Avenue South and 51st Avenue South. The description of South 160th Street provided on page 100 of the DEIS and page 5 of Appendix E more typically describes the sections of South 160th Street west of 51st Avenue South. Narrow shoulders typically exist adjacent to South 160th Street between 53rd and 51st Avenues South (See the revised description of South 160th Street in the FEIS). While the number of school children expected to originate from the proposed Valley View Estates project is unlikely to be high, the limited pedestrian facilities due to the narrow shoulders on this road section as it currently exists is acknowledged. It is suggested that widened shoulders on South 160th Street between 53rd and 51st Avenues South be provided to faci- litate safe pedestrian (particularly school children) access between the site and 51st Avenue South. The widened shoulder should be a. minimum of four feet wide. While the potential for hazard is acknowledged, this pro- ject does not directly cause a substantial increased hazard. It is The TRANSPO Group's understanding that the City may require the deve- loper to provide sidewalks along 53rd Avenue South and Slade Way adjacent to 183 the proposed project frontage by City ordinance, which would facilitate tra- vel along these frontages. 4. Comment acknowledged. In the revised EIS, it is state that the proposed development may be operated as a rental apartment complex, sold as con - dominiums, or a combination of either. Even it sold as condominiums, indi- vidual units may subsequently be rented. 184 JOEL E. HAGGARD ATTORNEY AND COUNSELOR AT LAW SUITE 2426, FINANCIAL CENTER 1215 FOURTH AVENUE SEATTLE, WASHINGTON 98161 (206) 682 -5635 OUR FILE NO: January 25, 1985 Mr. Brad Collins Planning Director City of Tukwila Tukwila City Hall 6200 Southcenter Blvd. Tukwila, Washington 98188 RE: Valley View Estates Draft EIS Dear Brad: On behalf of the applicant we have reviewed your DEIS for Valley View Estates. The third and fourth objective of the applicant (see pp. 1, 50, 52) are subject to limits of feasibility and existing law and are not to be construed as a blank - check for the imposition of any or all conditions on the building permit. While the City may have authority to impose some conditions on the permit pursuant to SEPA the authority is limited by RCW 43.21C.060, RCW 82.02.020 and case law. SEPA limits imposition of conditions to specific adverse environmental impacts, which conditions must be reasonable and capable of being accomplished. We do not necessarily agree that each or all impacts listed at pages 21 -23 and 146 -148 are adverse, much less sig- nificant. RCW 82.02.020 prohibits the City from imposing any tax, fee or charge, either direct or indirect, on this proposed development. No payment or "voluntary agreement" can be required unless the City establishes that it is reasonably required as a direct result of the proposal. The applicant has already agreed to including many mea- sures as part of its proposal. These have generally been identified in the DEIS as "Mitigating Measures" but really 185 Mr. Brad Collins January 25, 1985 Page 2 are part of our proposal and not to mitigate the pro- posal. Subject to some rewording for clarification and legal limits, these measures are enclosed. The City has already indicated that some changes are needed in the complete plans which have been sub- mitted. Review of the DEIS indicates other changes or design modifications may be required or desirable. And other changes or design modifications may result from the Board of Architectural Review or the building permit process. We could anticipate that any changes would not permit an increase in the number of dwelling units but could entail apartments configured in a fewer number of buildings or movement or change of location for actual building footprints, changes in unit square footage, loc- ation of and shelter for parking or play areas, reduction of the number of units with no reduction of total unit square footage, exterior design, etc. As you indicated at the public meeting on January 22, 1985, changes or design modifications to the plans are permitted but not for all elements of the project, please specify the range of change permitted. We would expect that the FEIS would be . adequate to handle subsequent changes so long as a change does not cause a significant adverse impact not adequately analyzed. Parenthetically, we would not interpret the comment on page 91 regarding no alteration "in any way" as being consistent with Tukwila's code, TCC 18.70.050. Would not a unit occupant be allowed to enclose his /her deck if he /she wants. See TCC 18.70.050(1). We recognize that many comments, for example on pp. 21 -23 and 146 -148 are judgmental and because they appear in your DEIS this does not establish the truth or falsity of the judgment. We are somewhat concerned about the apparent lack of basis for allegations regarding "potential" health aggravation (see pp. 68, 21). While many things are "potential ", we do not believe that this means they are probable. As with the suggestion about noise mitigation outside (see pp. 84, 88), neither SEPA nor the UBC requires perfection and we would anticipate a reasonable approach in assuring that the right job is done for the benefit of the future residents. 1 1 3 Mr. Brad Collins January 25, 1985 Page 3 The EIS process may be somewhat unfamilar to readers of the DEIS. We suggest that you provide in the FEIS a description of the detailed review you and other City personnel gave to directing and approving the docu- ment. Certainly your efforts have been extensive and the contribution City employees have made should be positively recognized. JEH /dm 0055D cc: Dr. Herman Allenbach 187 Sincerely yours, Joel Haggard ATTACHMENT 1 A. Earth: All recommendations contained within the geotechnical report will be complied with by the project sponsor, including the following summarized below: 1. The existing deep drainage facilities on the I -5 right -of -way shall be continued to be monitored and maintained by the State of Washington and Department of Transportation, as per corres- pondence dated December 20, 1984. 2. Slope movement shall be monitored through an instrumentation program which is to be maintained through the construction phase and during the life of the project. Initial monitoring shall be undertaken by the contractor /developer during construction and early occupancy phases. Sub- sequent monitoring shall be the responsibility of the homeowner or homeowners association for a period of two years. 3. Site grading shall be undertaken during the summer -fall months (unless otherwise approved by the City) when the least amounts of rainfall can be expected and surface runoff and seepage from springs should be somewhat diminished. 4. All cuts steeper than 3:1 horizontal to vertical (33 percent) shall be supported by retaining structures constructed and backfilled per specifications of the geotechnical report. 5. Building foundations and drains shall be constructed per specifications of the geo- technical report. 6. City of Tukwila requirements for grading and excavation will be followed. 7. Plastic sheets and mulch will be used on portions of the expossed soil areas during construction to minimize erosion. 8. Landscaping shall be installed during the first planting season following construction and will include plants suitable for the stabilization of the surface of steep slopes. 9. Collection of seepage and springs will be done during construction to minimize surface flow. 188 B. Air: 1. Measures to control construction dust such as watering, cleaning and sweeping of streets at the end of hauling activities shall be performed by the contractor whenever necessary. C. Water: 1. A stormwater detention system for a 10-year storm capable of detaining 2,500 cubic feet of water will be installed. The detention system will also have an emergency overflow. All required temporary sedimentation and control facilities will be constructed and in operation prior to paving and building construction. 2. Catch basins and oil /water separators are proposed within the on -site drainage collection system. 3. Permanent French drains will be installed along the upslope sides of all parking areas, and along the east side of the building units. 4. Foundation drains will be installed and connected to drain lines along the east property line so the flow can be disposed of off -site. 5. A temporary storm management and erosion control measure will be employed during construction. Where possible, natural vegetation for slit control shall be maintained. Proposed interim drainage control measures include placing straw - bales in drainage ditches directing runoff to two interim detention ponds, seeding and jute matting. 6. All temporary siltation ponds shall be maintained in a satisfactory condition until such time as cleaning and /or construction is completed and permanent drainage facilities have been approved and operational. 7. Prior to site clearing, an interceptor trench will be installed at the toe of the roadway fill along the western boundary of the site. 8. Temporary drainage swale will be installed to collect runoff immediately following site ' clearing and grubbing. 9. A portion of the existing perforated deep storm system will be abandoned and replaced by the contractor /developer with a new storm line to 189 handle off -site runoff. The existing storm line that is above ground and leaking will be repaired. 10. The contractor /developer will maintain the proposed on -site drainage control facilities during construction. The homeowner or homeowners association will assume maintenance responsi- bility for these facilities after completion of the development for a period of two years. 11. Cleaning of streets and parking areas shall be undertaken whenever necessary during construction by the contractor /developer, or as requested by the City of Tukwila during construction. D. Flora: 1. Landscaping shall be installed as per the ap- proved landscaping plan and installed during the first planting season following construction and will include plants supportive of stabilization of the surface of steep - slopes. 2. The southwestern portion of the site will remain in its natural state. Disturbed areas not proposed to be landscaped will be treated for erosion control by seeding with clover and rye or ivy. E. Noise 1. Double wall construction and 1/2 inch gypsum wall boards shall be utilized. 2. Insulation shall be a minimum of R -11. 3. All windows shall be double - glazed. 4. Construction will not occur before 7 AM on weekdays and 9 AM on weekends, or after 10 PM. All construction equipment will be required to have a proper muffler. 5. An eight -foot high solid continuous fence around the eastern half of the proposed children's area will be provided to reduce the average noise levels by about 10 dBA, to 55 dBA or less, which is the minimum level for avoiding speech inter- ference according to EPA's Noise Guidelines. F. Light and Glare: 1. Parking lot lighting will be directed so that no direct light spills off the perimeter of the site. 190 G. Transportation /Circulation: 1. A 20 vehicle on -site parking overflow will be provided in the area designated RMH in the western portion of the site adjacent to 53rd Avenue. 2. The developer will work with Metro Transit to ensure a safe, convenient bus stop location for project transit patrons adjacent to the Valley View Estates site. 3. A left turn lane for westbound to southbound left turns from Klickitat Drive to 53rd Avenue South will be provided. H. Public Services: 1. Smoke detectors and one fire extinguishers will be provided in each unit as per the U.B.C. 2. A a 20 foot wide unobstructed driving lane with 35 foot turning radius will be provided to assure fire lanes and emergency vehicle access. 3. Protective curbs or guard posts for all sprinkler valves, hydrants, gas meters and transformers will be provided. I. Police: 1. A close working relationship between the dev- elopers and the Police Department's Crime Prevention officer will be maintained throughout the planning and building phases of this project. J. Parks and Recreation: 1. A children's play area will be provided as per the building plans. 2. All requirements under Section 18.60.200, "Recreation Space in Multiple Family Districts" will be complied with. K. Maintenance: 1. The contractor will insure that the trucks carrying excavation loads will be covered with canvas or tarp if necessary for dust control. 2. The developer will provide street cleaning during construction when necessary. 191 3. Casing or sleeves will be placed around the 12" sanitary sewer line underneath those proposed building to provide access for maintenance. The carrier pipe will be sealed at both ends to prevent leakage into our out of the pipe except at vent pipes which will extend above ground. L. Energy: 1. Insulated walls, floors, roof and glass will be used throughout the structures based upon the energy analysis of the buildings. M. Utilities: 1. All utilities, i.e., telephone, electrical and cable lines shall be installed underground. 2. All utility installation shall be coordinated with the appropriate utility. N. Aesthetics: 1. Existing vegetation will be maintained along the eastern portion of the site where practical. 0. Historical /Archaeological: 1. In the event that cultural materials are dis- closed during construction, work in the immediate area will be discontinued and the Office of Archaeology and Historic Preservation will be notified. 0069D 192 Response to comments made by Joel Haggard, Attorney 1. Comments acknowledged. The revised FEIS uses the terms "will" or "shall" to indicate mitigating measures that have been incorporated into the project by the proponent and "may" or "could" to indicate measures that could be required by the City as conditions to reduce identified significant adverse environmental impacts. 2. Project changes are permitted that do not result in additional adverse environmental impacts which would require supplemental SEPA review. For example, between the DEIS and the FEIS, the project was revised to relocate the 12 -inch sewer line on the site, avoiding the potential adverse impacts identified in the DEIS in building over this line. Additional changes that could be required during City review of the proposal include mitigating measures as described in the EIS that became conditions of permit approval intended to reduce or eliminate potential adverse environmental impacts. 3. The Noise and Human Health sections of the FEIS have been revised to more clearly state the types of potential hazards that may exist at the site, relative to adopted government standards, and measures available to reduce these potential hazards. 4. Comment acknowledged. A memorandum, explaining the purpose of the document and the City's review procedures, is included. 193 Dames & Moore City of Tukwila 6200 Southcenter Boulevard Tukwila, Washington 98188 Attention: Mr. Ross Earnst, P.E. City Engineer Gentlemen: 155 N.E. 100th Street, Suite 500 , P.O. Box C - 25901 Seattle, Washington 98125 -0711 (206) 523-0560 TWX: 910 -444 -2021 Cable address: DAMEMORE January 29, 1985 We are pleased to present our "Report of Engineering Consultation, Review of Draft Environmental Impact Statement; Proposed Valley View Estates," for the City of Tukwila. The scope of our consulting engineering services was outlined in an attachment to your standard consultant agreement entitled "Consultant Scope of Work" as presented in our transmittal dated January 11, 1985. Our services were authorized on January 15, 1985. We appreciate the opportunity to provide these engineering services to you and trust that the information provided in the attached report meets your current needs. If you have any questions or require further information, please contact us. HLC:DAP:RRH:adn 06833 - 031 -005 10 copies submitted Yours very truly DAMES & MOORE By Harba s L. Chabra, P.E. Associate 195 REPORT OF ENGINEERING CONSULTATION REVIEW OF DRAFT ENVIRONMENTAL IMPACT STATEMENT PROPOSED VALLEY VIEW ESTATES for THE CITY OF TUKWILA INTRODUCTION This report presents the results of our engineering review of the draft 1984 Environmental Impact Statement (EIS) and selected geotechnical and hydrological support documents for the proposed Valley View Estates condominium development located southwest of the junction of Interstates 5 and 405 in Tukwila, Washington, as shown on Plate 1. The proposed development is located in an area which has a history of slope instability. The stability of the project site has been improved by remedial drainage measures installed by the Washington State Department of Transportation (WSDOT) during construction of Interstate 5. These drainage facilities include systems of vertical and /or horizontal drains, a number of which are present along the east side of the proposed development. The existing WSDOT drainage system is considered critical to maintaining stable slope conditions above the roadways. The primary focus of our review was to evaluate the adequacy of the geotechnical and hydrological aspects of the mitigative measures presented in the subject draft EIS. SCOPE The scope of our consulting engineering services is outlined in Exhibit A to your standard consultant agreement. Our scope of services includes a review of documents, reports, and analyses prepared by others and preparation of a final report presenting the findings. We have not performed any new field investigations and have confined our opinions and review to information generated by the consultants retained by Dr. H. M. Allenbach and Puget Western, Inc. Specifically, the scope of our services includes: 196 1. Review of the 1984 Draft Environmental Impact Statement prepared by R. W. Thorpe and Associates, Inc. 2. Review of memorandum from.Mr. Phillip Fraser to Mr. Brad Collins dated November 9, 1984 and the WSDOT letter from Mr. R. F. Johnson to Mr. Glenn McKinney of Stepan and Associates dated 'December 20, 1984. 3. Review and comment on the adequacy and appropriateness of the geotechnical and hydrological report prepared by GeoEngineers, Inc. 4. Review of I -5 investigation reports dated April 14, 1966 and June 21, 1968 prepared by Shannon & Wilson for WSDOT. 5. Meetings with representatives of WSDOT and GeoEngineers, Inc., to obtain and /or review existing site data. 6. Determination of the adequacy of available data on existing site conditions relative to the planned Valley View Estates development. 7. Determination of the adequacy of data, conclusions, and recom- mendations contained in the draft EIS relative to soil stabili- zation at the project site, including the identification of impacts and alternatives and the application of mitigative measures addressed in the draft EIS. 8. Preparation of a written report which summarizes our engineering services and the results of our review. SITE CONDITIONS A detailed description of surface and subsurface soil and ground water conditions near the project site is summarized in reports presented or referenced in the draft EIS. These documents should be referenced for a proper understanding of the nature of the subsurface material, the mechanisms which have caused the area to have a history of slope instabi- lity, and the remedial measures that have been constructed to improve 197 slope stability in the project area. Based on existing information and available data obtained from monitoring of slope movements since the WSDOT drainage facilities were installed, it appears that the subject area has been sufficiently stabilized to the extent required for a high- way system. For completeness and referencing purposes, we are presenting several figures from the draft EIS in this report. The general area of the pro- ject site is presented on the site location map, Plate 1. A preliminary layout of the proposed development is presented on the site plan, Plate 2. A plan of the completed drainage measures installed by WSDOT in the vicinity of the project site is presented on Plate 3. CONCLUSIONS The review comments presented below are based on our geotechnical and hydrological evaluation of the documents identified in Scope Items 1 through 4, data obtained from WSDOT and GeoEngineers, Inc., and meetings or telephone conversations with representatives of WSDOT and GeoEngineers, Inc. GENERAL COMMENTS 1. We conclude that it would be possible to develop the property without endangering the overall stability of the site only if ade- quate provisions are made to (i) monitor and maintain the existing WSDOT drainage facilities; (ii) safely collect and divert both sur- face and subsurface- ground water away from the project site; (iii) monitor and evaluate piezometric levels and any slope movements during the life of the project, and (iv) implement installation of additional subsurface drains as necessary during the life of the project to control the rise of the water level in the lower sandy gravelly soils (Unit C). It is our opinion that the draft EIS has not developed clear and satisfactory commitments from the contrac- tor /developer, WSDOT, and future homeowner's association relative to such long -term monitoring, maintenance and implementation of reme- dial measures that may be necessary. 198 2. While the statement "all recommendations contained within the geotechnical report [Appendix A) will be complied with by the pro- ject sponsor ... ". may be acceptable, we do not believe that the detail of certain mitigative measures presented in the text of the draft EIS is sufficient to determine the adequacy of the draft EIS. This general comment particularly applies to certain measures related to soil and ground water control that will be critical to evaluating and maintaining the stability of the slopes. Discussions of these areas are provided in the following comments. 3. We have reviewed the City of Tukwila memorandum from Mr. Phillip Fraser to Mr. Brad Collins dated November 9, 1984 and generally con- cur with the review comment provided therein. We assume that these comments on the draft EIS are being submitted by the City of Tukwila and as such we have not tried to specifically restate any of these comments in our report. We note that the WSDOT letter from Mr. R. F. Johnson to Mr. McKinney of Stepan & Associates attached in Appendix G of the draft EIS responds to only a few selected issues, the remainder of which have yet to be addressed in the draft EIS. Drainage of Deep Aquifer: Since the continued satisfactory perfor- mance of the existing WSDOT system of vertical wells and horizontal drains is required to maintain existing slope stability, the draft EIS should be updated to more completely identify the existing facilities and its maintenance requirements. The effectiveness of the WSDOT deep drainage system can be expected to deteriorate slowly over a period of years, and drain maintenance data available to date indicates that some of the horizontal drains appear to be getting progressively shorter with time. A sufficient data base is not yet available to determine the loca- tion and extent of this potential problem, which may eventually require installation of additional drains to control the ground water level. The text of the draft EIS should also be updated to clearly address the requirement and identify responsibility for long -term monitoring and evaluation of the piezometric levels at the site so that any necessary remedial measures can be implemented in a timely manner. The lack of direct control over drainage of the deep aquifer is a major concern that should be emphasized. The drainage system was 199 4 5 installed and is controlled by WSDOT and is located on land which is not controlled by the Valley View Estate. The continued performance of the WSDOT drainage system is critical to the proposed condominium develop- ment. Whereas the WDSOT drainage system appears an appropriate design for a highway system, it may not afford the higher level of protection against instability that would normally be associated with a housing development on a potentially unstable hillside. The WSDOT installed piezometers have not been monitored in a regular and systematic manner since about 1968, and thus there is a lack of data from which to fully assess the past, performance of the WSDOT drainage system or to predict with a sufficient level of confidence if the system will continue to function properly in the future. Near Surface Drainage: The text of the draft EIS should more fully identify components of the drainage facilities that are proposed to collect and control near - surface ground water seepage in order to main- tain the stability of the surficial soils. Site drainage should be designed to eliminate or minimize the opportunity for ground water recharge, such as lining surface drains to prevent infiltration and constructing subsurface drains to minimize the protential for leakage or breaks. The text states that a ground water interceptor trench will be installed at the toe of the roadway fill along the entire western boun- dary of the site, while Figure 1 of Appendix A shows a proposed intercep- tor trench only along the portion of that boundary north to South 160th Street and the Site Utility Plan on Figure 16 of the text does not even identify the proposed interceptor trench. It is our opinion that more details of the interceptor trench, such as minimum depth, alignment, tight line connections to the storm water collection and disposal systems, etc. should be discussed at the appropriate location(s) in the text. Permanent french drains are proposed along the upslope sides of all parking areas and along wet areas near the east (downslope) side of the condominium units. Again, we believe additional details as noted for the interceptor trench should be included at the appropriate location(s) in the text. 200 The discussion of foundation drains that will connect to storm sewer lines along the east property line should also be expanded to include drains for individual retaining walls, retaining wall sections of the buildings, and perimeter drains along the outside of the building foun- dations. Stormwater Detention System: The proposed development specifies installation of a stormwater detention system for a 10 -year storm, as normally required by the City of Tukwila. Stormwater would be stored in oversized pipes and released at a controlled rate. Due to the sen- sitivity of the site and potential effects of development on adjacent facilities, we question whether or not the stormwater detention system should be sized for a 100 -year storm. The draft EIS should more clearly state whether the existing storm sewer systems are adequate to carry the peak flows from the site, and where overflow water would be routed if the capacity of the stormwater detention system were exceeded during a large storm event. Monitoring of Slope Stability: The discussion of the "instrumentation program" to monitor slope movement that is proposed to be maintained through the construction phase and during the life of the project should be expanded to discuss the required instrumentation (slope inclinometer(s), settlement and alignment hubs, piezometers, etc.) and development of an adequate data base, as well as critical requirements for long -term monitoring, maintenance, data and stability evaluation, and implementation of any necessary remedial measures. Construction on Steep Slopes: The location of the proposed con- dominium units are shown on the Site Plan, Plate 2. We note that most of Units 3 through 18 are generally located on the downslope, somewhat flatter portion of the site; however, Units 1 and 2 are presently located in a steeper uphill area which apparently has slopes of 30 to more than 40 percent. The advisability of construction Units 1 and 2 on such steep slopes near the upper part of the 1960 -1961 earth slide is questioned. Dynamic Slope Stability: The draft EIS and the geotechnical/ hydrological report in Appendix A appears to discuss static stability of the project area in sufficient detail. We believe that a brief 201 discussion of dynamic stability of the project site would be appropriate and should be added to the draft EIS. Construction Monitoring: We conclude that available data on subsur- face soils and ground water conditions within the project site are ade- quate for design of the proposed development. The geotechnical report recommends that sufficient design review, construction monitoring, testing, and engineering consultation "should" be provided during construction to confirm subsurface conditions, provide recommendations for necessary design changes, and evaluate adequacy of earthwork and foundation installation activities. Due to the sensitive nature of the project site, the text should be updated to include these review and monitoring requirements as a mitigative measure that "will" be imple- mented prior to and during construction. Sequencing of Construction: The soils report (Page 12 of Appendix A) addresses the need to stage construction of the units so that alter- nate building sites are excavated and retaining walls are built, braced, and backfilled prior to beginning excavation for the intermediate buildings. This requirement for construction sequencing should be brought forward into the text of the draft EIS. Earthwork: While the text does summarize the geotechnical engi- neer's recommendation that site grading be undertaken during the late summer - early fall months; it should be updated to clearly state that (i) earthwork on this property will at best be very difficult; (ii) any fill placed to support the condominium structures will not be permitted to extend above the original ground surface elevation; (iii) no areas are to be left partially graded or without sufficient drainage capability through the winter and spring season; and (iv) construction is to be scheduled so that site grading, drainage installation, foundation construction, and surface stabilization shall be completed in any given area within the dry months of a single construction season. A statement addressing if or where unsuitable soils will be temporarily stockpiled or permanently placed on site should also be added. 202 1 13 14 15 SUMMARY In general, we believe ,that the data, conclusion, and recommen- dations contained in the draft EIS, its appendices and referenced docu- ments relative to soil stabilization at the project site will be sufficient when the draft EIS is updated to address the concerns expressed in this report. We recommend that the existing draft EIS be rewritten to address the stated concerns and be resubmitted to the City of Tukwila for additional review and comment. We believe that the sen- sitivity of the project site warrants incorporation of all the remedial measures addressed both in the draft EIS and this report. Incorporation of all stated remedial measures will be important for the proposed pro- ject, since their exclusion could result in increased exposure to the risk of reactivating earth movements at the site along with an increase in potential liability to all parties associated with the project. We remain concerned that many details may be left in the appendices rather than being presented within the text of the draft EIS. The vali- dity of the following statement made on page 35 of the draft EIS "Mitigating measures associated with the proposed development would improve the slope stability on site" will be a function of many factors, including proposed versus actual construction methods and features, the level of site monitoring performed by qualified personnel both during construction and for the life of the project, etc. It would be better for the draft EIS to state that "Mitigative measures ... would generally be expected to improve the stability of the surficial soils on site." We also are concerned that there is a lack of data from a systematic monitoring of the WSDOT piezometers from which to adequately assess the past performance of the WSDOT drainage system or to predict with a suf- ficient level of confidence if the system will continue to function pro- perly in the future. It is our opinion that the draft EIS and its appendices have pro- perly identified potential impacts from the planned development and alternative proposals. We note that remedial measures intended to stabi- lize the hillside have not addressed up front installation of additional horizontal drains into the aquifer; however, it is not clear that this 203 remedial measure would necessarily be required prior to site development. Continued monitoring of piezometric levels in the hillside is highly recommended; and if conditions warrant, additional horizontal drains should be installed to control the water level in the hillside. SPECIFIC COMMENTS We offer the following specific comments on the draft EIS. Note that in our review we have not necessarily identified the locations(s) where the text would need to be revised to sufficiently address concerns raised in the General Comments. Page 14, First Bullet - This bullet is representative of the vague commit- ments to monitoring and maintenance of on -site drainage facilities by a future homeowner's association. The "could be" type of wording would be objectionable if it ends up applying to monitoring and main- tenance of critical drainage provisions. Page 19, Maintenance - In this and all other places "maintenance" is discussed in the draft EIS, it is not apparent why maintenance of drainage facilities during and after construction is not even addressed or referenced, especially considering the often mentioned statement "A potential soils loading problem which would contribute to unstable slope might occur if a sewer line break went unnoticed or unrepaired for a period of time." Page 60, Mitigating Measures (Geology and Soils) - All the recommendations contained within the geotechnical report will need to be complied by both the project sponsor and the homeowner's association, including, but not limited to, those summarized in the text. Also reference numerous concerns raised in the General Comments. Page 63, Erosion Measure #5 - This item should be expanded, or another measure added, to address the following recommendation of the geotechnical engineer: "Localized seeps which are not intercepted by the general drainage facilities may have to be drained and /or excavated and backfilled with gravel or crushed rock to resist damage to the slope face. 204 20 21 22 23 24 Page 71, First Sentence - Seeps observed within the upper portion of the site but outside the area of planned development should not necessarily be left in their natural state. It is our opinion that all seeps within the site be located and the effects of the resulting flow mitigated on a case by case basis. Page 72, Measure #1, Seventh Sentence - Temporary sedimentation and drainage control facilities should be in operation prior to general site grading activities. This sentence should be revised and relo- cated to Measure #5. Page 74, Groundwater, First Paragraph - The draft EIS appears to be misinterpreting the geotechnical engineer's ground water data. It is not correct to say the water level varies from 6 to 40 feet below the ground surface. This should be revised to state that water levels observed on November 18, 1983 varied from about 6 to 45 feet below the ground surface. Seasonal fluctuations in the water levels would normally be expected, and subsequent readings will not necessarily show the same water levels as observed on that date. Page 130, Figure 16, Site Utility Plan - This figure should be updated to show all major proposed utilities, such as the ground water interceptor trench along the western edge of the property, french drains, etc. and their connections to the existing storm sewer system. Page 132, Utilities, Sewer - The draft EIS indicates that some of the proposed building units are to be built over an existing cast iron sewer main. The text states the fact that the City of Tukwila does not allow placement of buildings over sewer lines; however, it pro- poses to mitigate the potential conflict by casing the 12 -inch diameter sewer line in a "larger" carrier pipe under these buildings. Due to the sensitivity of the site and the considerable earthwork that would be required to excavate and encase the sewer in a carrier pipe large enough to provide access for repair activi- ties, we believe that it would be more feasible to relocate the sewer line. The proposed utility plan in the draft EIS should be modified to avoid construction of any structures over the existing sewer line. 205 Appendix A, Page B -1 - For completeness, an addendum to the soils report summarizing piezometric levels and inclinometer data obtained bet- ween November 1983 and the present should be added to Appendix A. -o0o- LIMITATIONS This report has been prepared for the City of Tukwila in accordance with generally accepted professional engineering principles and prac- tices, for use by the City of Tukwila and its consultants in review of the 1984 Draft Environmental Impact Statement for Valley View Estates. No other warranty, either expressed or implied, is made as to the nature of the conclusions and recommendations. The content of this report is not intended for the use by other parties or for other purposes. It may or may not contain sufficient information for other uses. We remain available to confer with you on any aspects of our engi- neering consultating services. January 29, 1985 Respectfully submitted, DAMES & MOORE By Harbans L. Chabra, P.E. Associate µ,Q4 4exte- David A. Pischer, P.E. Project Engineer 206 29 0.3833 -031 Plata 1 1 0 V � q \a r CD L 4UK Vtl IL A v 7 /� SEA °TA(� I � j 1 J , B S � 9808V1 #04. e 405 40. 84 �. D LI SOU hCE TE 0 R. e '4 aarcondev Blvd ,� 1 1nT ) R k% -_ -_- -- Cl A h� -- 8 170811 S8 0 Q 0 .4. 0 <> o r� rt _ovation cl Me NORTH SCALE R.W. Thome 1a Aseocitates 207 Dawxaa t3 alcove 0.3833 -031 Plata 1 13 14 15 t —1 LT 12" DIAMETER DUCTILE IRON SEWER LINE NOTE: PROPOSED INTERCEPTOR TRENCH TO BE LOCATED IN THE FIELD. TRENCH TO BE ALIGNED ALONG CONTOUR AND DRAIN FROM NORTH TO SOUTH. -4,-D EXPLANATION: BORING LOCATION AND LETTER DESIGNATION DM -1 9 DAMES C MOORE INVESTIGATION 1961 / 0 80 160 m SCALE IN FEET IP O O REFERENCE: DRAWING ENTITLED "VALLEY VIEW ESTATES" BY WILSEY C HAM INC, DATED 5/3/62 1 G.oEngIn..Ps Inc. 1 SITE PLAN • - • ■ ■ .1 "Lo • • 0 ��. + . •t • :.\ • got, wait (R-'M .., i `` \ \ . • • \ .4 • ••••. • '••••• ■ • Project Site —13:\S Approximate Extent of Slide 4 -20 -61 0 100 200 300 Scale In Feet Reference: Drawing entitled "Plan of Completed Remedial Measures" by Shannon & Wilson dated March 31, 1966. Legend: Horizontal Drains (existing) o•. ....•--•-•••••••Original Test Drains o------Recommended Drain (Grade: 1 -3%) =Cylinder Pile Wall °m• °s•Add-sa•Existing or Proposed Right of Way ♦ Additional Vertical Drains (6 -9 in. dia.) • Large Diameter (5') Deep Well 4:1 Final Excavated Slope (horizontal:vertical) • Piezometer Installed During 1966 Investigation GeoEngineers Inc. 1 HORIZONTAL DRAIN AND WELL SYSTEM 209 Dames & Moore Job No.6833 -031 Plate 3 Response to comments made by Harbans L. Chabra and David A. Pischer, Dames and Moore 1. The Earth and Water Sections of the FEIS and /or the GeoEngineers, Inc. geotechnical /hydrological report (Appendix A) has generally been modified to adequately include and /or address the concern raised by this comment on the DEIS. 2. See response #1 above. 3. See response #1 above. 4. See response #1 above. 5. See response #1 above. 6. See response #1 above. 7. The EIS has been updated to better identify storm water discharges, flow paths, and the offsite properties that are expected to receive these discharges. The revised discussion of existing site drainage conditions, impacts, and proposed mitigative measures are presented in the section under "water" entitled "Surface Water Movement, Quantity, Quality, Runoff /Absorption of the revised EIS. 8. See response #1 above. 9. See response #1 above. 10. See response #7 above. 11. GeoEngineers, Inc. has issued a revised Geotechnical and Hydrogeological report (Appendix A) and the text of the FEIS has been updated to better identify existing conditions and include general requirements for (i) moni- toring of soil and groundwater conditions; (ii) maintenance of existing and proposed facilities; and (iii) posting of bonds by the developer to provide the funds for necessary mitigating measures. Refer to revised Earth Resources discussion in the FEIS. 12. As shown on the revised site plan (Figure 3) the proponent has relocated Units 1 and 2 somewhat downslope to minimize construction on the steeper slopes. See also, revised Geotechnical report (Appendix A) and revised Earth Resources section of the FEIS. 13. See response #1 above. 14. See response #1 above. 15. See response #1 above. 16. See response #1 above. 210 17. See response #1 above. 18. See response #1 above. 19. See response #1 above. 20. See response #1 above. 21. See response #1 above. 22. The "Maintenance" sections of the EIS have been updated to include main- tenance of existing and proposed drainage facilities during and after construction. 23. See response #1 above. 24. See response #1 above. 25. See response #7 above. 26. See response #1 above. 27. See response #1 above. 28. The proposed development of the EIS have been revised to reflect that por- tions of the existing 12 -inch cast iron main will be relocated so that it will not be underneath proposed building locations, as shown on the site utility plan on Figure 16. The realignment traverses the hillside higher upslope, resulting in a maximum excavation depth of approximately 20 feet. The maximum depth of excavation for the existing sewer line in this area was on the order. of 15 feet. In the opinion of GeoEngineers, Inc., the proposed realignment of the sewer is feasible provided that the excavation is pro- perly designed and constructed (refer to the October 16, 1985, letter from GeoEngineers, Inc., presented in appendix A of the EIS). 29. See response #1 above. 211 213 cor, O € b . k-)-' �QaYSk� -L av•- T (M 1 ck 3e&,„ 15+ c o ovt o_na t- 3 lr'k-e_ d 0.A 6 oLiv,2k. i/1 e c 4 1 `Ft' COS eL +L.+ -et S s gb vr.e-4w lirkt t ,t +. 4\:AS & s t s tic Ei a►� :ev- �eval cOLk r; r tslc- 0‘01/ evh.eIA-fr i3 y1 e v e.r fed . 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Tow-- c y'w c ca_ n o.- c..v,42_ `F a LI�J 7 C v h 50 L 4 i 0' /h ©r'e- eN e Si`or m aSSur -toh he lit o rrc^!_ k,1,Vr f re c itp -(41-f' cfrt (� o �Gi C�`fl /C c - 7" o p .:2.rc k o k 64- Cira ;AS a,/ s'i e t) (c/ r aSf tare d KV Cis, 215 Sncere_H 5 6 Response to comments made by Fred Bigelow, resident 1. The Earth and Water Sections of the FEIS and /or the GeoEngineers, Inc. geotechnical /hydrological report (Appendix A) has generally been modified to adequately include and /or address the concern raised by this comment on the DEIS. 2. A detailed risk assessment that could accurately quantify the probability of slope movements under various site conditions is generally not required for site development and may not realistically be able to be performed for this project. However, the factor of safety for slope stability can be assumed to imply a general level of risk (low, moderate, high) for slope movements. The text of the EIS has been revised to include such statements as appropriate. 3. See response #1 above. 4. GeoEngineers, Inc. has issued a revised Geotechnical and Hydrological report (Appendix A) and the text of the FE1S has been updated to better identify existing conditions and include potential requirements for (i) monitoring of soil and groundwater conditions; (ii) maintenance of existing and proposed facilities; and (iii) posting of bonds by the developer to provide the funds for necessary mitigating measures. Refer to revised Earth Resources discussion in the FEIS. 5. Subsurface drains will be required to be designed and constructed to prevent reinfiltration of water and to minimize the potential for leakage or breaks. Trigger levels for .slope movements that are to be part of the site main- tenance and monitoring program are less than soil movements that would generally damage a buried conduit. 6. The EIS has been updated to better identify storm water discharges, flow paths, and the offsite properties that are expected to receive these discharges. The revised discussion of existing site drainage conditions, impacts, and proposed mitigative measures are presented in the section under "water" entitled "Surface Water Movement, Quantity, Quality, Runoff /Absorption of the revised EIS. 216 Sincerely, :i t Crain ichard Goe Page 149 Short Term vs Long Term The alternative development of the site as a single family area is ignored. Page 121 Parks & Recreation Mileages shown to various recreation areas are basically incorrect. Correct distance to Tyee High School, Chinook Jr. High, and Bow Lake Elementary is 2.5 miles. Shortest possible distance to Foster High School is 1.6 miles, other distances shown appear to be similarly underestimated. 17 Page 126 Drainage & Instability The present hillside drainage system is approximately 20 years old. If above ground pipes are leaking, does this not indicate entire system is possibly marginal in its condition? Was this system not designed to counter slide and drainage 18 problems with the hillside in approximately the same condition that it is in today and if so will it be adequate with the stresses this development would place on the hillside? Pages 141 & 142 Pollution Dense & growing vegetation on a hillside is an effective 19 screen from auto polluted air generated from Southcenter & I -5, much of which will be lost with this development. Page 151 Alternatives The conclusion of the EIS that the continuation of the property in its present state is highly improbable unless acquired by the city is not backed by any facts. Though as individulals we believe in the right of investors to a reasonable return on investments, we believe the proponents took a known 20 risk in this investment and that a development which appears to G have strong negative effects on the neighborhood is not in the best interest of the public. Also, it is not the city's responsibility to bail investors out of foolish decisions. Page 91 Land Use The EIS indicates that liablility insurance companys and lending institutions are unlikely to be supportive of this project due to unstable slope potential. It is felt that prior to approval of this building permit, the developer should be required to post TWO BONDS. One bond would insure that during construction, should the project be found to be unfeasible for any reason, funds would be available to restore the current environment and stability of the hillside. A second bond would insure that should the hillside slide away after completion of the project any time within the 50 year life projected in the EIS, all property owners whose property values would be affected by 220 21 such slide could be adequately compensated. Pages 132, 133, & 134 Sewers. It is understood how encasement of the 12" sewer main in a sealed vent carrier pipe could mitigate the problem of soil erosion going unnoticed from a leak in the line. However, unless the carrier pipe is large enough for a person to enter (presumably full of raw sewage) it is difficult to see how use of this device would aid in repair of any such leak. Mention is made in the EIS that this method has been used successfully under railways and roadways. However, it seems obvious that a repair in a leak under either of these could be handled by excavation which would not . appear applicable to an 8 unit condominium building constructed on unstable slopes. Page 39 Traffic It seems that the 1.5 vehicles per unit standard is too low. Based on the expected selling price of these units, it would be obvious the owners will be comparatively affluent and would be more likely to own 2 or more cars per unit and possibly .a boat, camper, trailer, etc. We believe parking requirements as recommended by the Tukwila Police Department letter in appendix D should be a minimum requirement. Page 101 Traffic We question the reason the traffic counts on the streets most critical to this project's streets are shown as estimates which appear to be low. 1 21 22 23 124 Page 98 Traffic We believe the intersection of S. 160th and 53rd S. is more of a problem than described. Cars coming up 53rd S normally turn west on 160th, which is the normal routing and therefore do not use their turn signals. Cars going straight through the 2 intersection also do not use their signals. Drivers moving East on S. 160th and turning north on 53rd S. are therefore unsure if approaching traffic is turning or going straight through. This problem is going to increase if this development is allowed. We believe this problem must be mitigated. Page 103 Traffic & Transportation We disagree strongly with the statement concerning left turns off of 53rd S. onto Klickitat. Though backups may not occur often due to relatively light traffic, at this time it is 26 virtually impossible to make this turn during evening traffic and hours of heavy shopping. Obviously this problem will be multiplied by additional traffic generated by this proposal. The EIS emphasises the availability of metro transit service on 53rd S., but since no sidewalks are planned within the 27 development or access roads, it appears that residents within the 221 Project would find that walking to the transit pick -up point would have to be done on the vehicular roadways. There are no existing sidewalks to support children's passage to the proposed Crestview Park. Appendix G Letter from W.S.D.O.T. to Engineering- Science Inc. dated March 28, 1984 This letter states that the 1 -inch "weep" drains are obstructed or pinched off and that measurements need to be taken to establish a data base for comparisions. This EIS does not indicate that this has been done. If this observation is valid it appears this problem must be addressed. Work comtemplated for this project, must not compromise the weep drains or accelerate this type of problem. 222 Response to comments made by Robert Crain and Richard Goe 1. It is the opinion of the geotechnical consultants that the deep- seated sta- bility of the project site would be jeopardized only if the WSDOT drains were to fail. The updated discussions and mitigating measures presented in the EIS are believed to adequately address these issues. See revised geotechnical /hydrology report, earth resources, and water resources sections of the FEIS. The EIS has been revised to include the mitigating measure that the City of Tukwila, its officers, employees, and agents be indemnified from all claims, damages, losses, or liabilities arising directly or indirectly from any earth movement on the site. The EIS also has been revised to include general statements regarding (i) potential bonds required of the developer and project owners, and (ii) a mitigating measure for covenants on the property deeds. 2. See response #1 above. 3. See revised comments on Residence Goals #1 and #2 in the FEIS discussion of Plans and Policies. 4. Comment acknowledged. 5. As indicated in the comment on this objective in the FEIS, this project would not cause an appreciable deterioration of air quality in the area. The State's emission control requirement is one effort to reduce existing pollutant levels. 6. It is the opinion of the geotechnical consultants that the deep- seated sta- bility of the project site would be jeopardized only if the WSDOT drains were to fail. The updated discussions and mitigating measures presented in the EIS are believed to adequately address these issues. See revised geotechnical /hydrology report, earth resources, and water resources sections of the FEIS. 7. Comment acknowledged. See revised comment on Objective #1 and previous response to comment #3 above. 8. Comment acknowledged. 9. See revised comment on Policy 1 - "Transition Areas" in the FEIS. 10. The EIS has been updated to better identify storm water discharges, flow paths, and the offsite properties that are expected to receive these discharges. The revised discussion of existing site drainage conditions, impacts, and proposed mitigative measures are presented in the section under. "water" entitled "Surface Water Movement, Quantity, Quality, Runoff /Absorption of the revised EIS. 223 11. See response #10 above. 12. See response #10 above. 13. GeoEngineers, Inc. has issued a revised Geotechnical and Hydrological report (Appendix A) and the text of the FEIS has been updated to better identify existing conditions and include potential requirements for (i) monitoring of soil and groundwater conditions; (ii) maintenance of existing and proposed facilities; and (iii) posting of bonds by the developer to provide the funds for necessary mitigating measures. Refer to revised Earth Resources discussion in the FEIS. 14. The proposed development and the EIS have been revised to reflect that por- tions of the existing 12 -inch cast iron main will be relocated so that it will not be underneath proposed building locations, as shown on the site utility plan on Figure 16. The realignment traverses the hillside higher upslope, resulting in a maximum excavation depth of approximately 20 feet. The maximum depth of excavation for the existing sewer line in this area was on the order of 15 feet. In the opinion of GeoEngineers, Inc., the proposed realignment of the sewer is feasible provided that the excavation is pro- perly designed and constructed (reference the October 16, 1985, letter from GeoEngineers, Inc., presented in Appendix A of the EIS). 15. Comment acknowledged. 16. See the revised discussion of Short -Term vs. Long -Term Productivity in the FEIS. 17. See the revised chart in the Parks and Recreation section of the FEIS for corrected mileages. 18. The Earth and Water Sections of the FEIS and /or the GeoEngineers, Inc. geotechnical /hydrological report (Appendix A) has generally been modified to adequately include and /or address the concern raised by this comment on the DEIS. 19. See revised Air Resources section in the FEIS for a discussion of the air pollutant impacts of removing vegetation. 20. See revised discussion of the Single Family Alternative in the FEIS. 21. See responses #1 and #10 above. 22. See response #14 above. 23. See Hearing Transcript, Response #7 to Darlene West. 24. See Hearing Transcript, Response #31 to Richard Goe. 25. Comments based on the experience of the authors are acknowledged. See Hearing Transcript, Response #19 to Barb Welsh. 26. See Response #3 to the King County Department of Planning and Hearing Transcript Response #8 to Darlene West. 224 27. See Response #3 to Metro and Response #3 to Carl Jensen, Attorney, as well as Hearing Transcript, Response #19 to Barb Welsh. 28. The WSDOT flushed the horizontal drains during the first two weeks of May 1985. The updated geotechnical report in Appendix A now includes the data base required for a better evaluation of the WSDOT drainage systems. 225 City Of Tukwila Planning Department 6200 Southcenter Boulevard Tukwila, Washington 98188 Dear Sir: January 20, 1985 As a concern property owner and a mother of our future, I'm very concern about the inconsistency and inaccuracy of the Draft Enviromental Impact Statement for Valley View Estates. Some of the points in question are as follows: 1. Complex Parking After careful examination of figures 3, 4, and the information given in the draft I have some concerns: For 108 unit complex there is not ample parking. The developer is allowing 1.5 spaces per dwelling where the police report dated September 9, 1983 suggested increasing to 2. Buildings 1 and 2 only indicates a total of 9 spaces for 12 units with no overflow parking. All overflow will probably park on Slade Way which is much closer then the overflow designed lot. This street parking will result in serious hazardous due to the fact that the street is narrow, no shoulders, dangerous curve and grade, and would increase accidents and vandalism. Also buildings 3 thru 18 doesn't have ample parking. For example on my street alone, 163rd Place there are 13 houses (4 with children of school age), there are 40 license vehicles averaging 3.07 per house. Per figure 3 buildings 14, 15, and 16 each have 2 units especially equipped for the handicap, but only 4 destinated parking spots. This inconsistency with the 1.5 stalls per unit developer allowed. There is no provisions for sidewalks for the handicap, no provisions for guest parking who are handicap, no provisions for a handicap mother to go to the children playarea -- steps only are indicated. 2. Schools There is repeated mention of approximatly 27 school age children attending Tyee, Chinook, Bow Lake, and Valley'View. According to Jim Mast of the Highland School District Transportation Division, the area where this complex is being proposed is located in the McMicken Height elementary School boudaries. Not a word is spoken about the impact at this school. Also according to Mr. Mast the children, our future, will be walking up to 160th and 51st to catch the School Bus. No provision to reroute the bus down to Slade Way for the following reasons: 227 2. a). No safe means for the bus to turn around b). Will not travel on 54th due to the fact its a one -way road c). No turn around in complex because its private property with speed bumps d). Not in a direct route to school without elimating all stops on 51st. 51st stops were first and have priority Due to icy and snowy conditions where the limited bus schedule for the children is in effect. The children will be walking up to 164th and Military Road. Which will bring up the next point! 3. Present Conditions of the Roads According to Page 100 the roads in the immediate area "... two lanes in fair to good condition with some local exceptions to potholes and /or poor pavement. Shoulder width is indicated as not narrow..." On 160th between 51st and 53rd North of present Metro Bus stop the shoulder width is 2 feet or less with a drop off. Is this adequate walkway for the safety of our children? On Slade Way just below the top of the hill the shoulder width is again 2 to 3 feet. Is this adequate to accomodate safe off road parking? Response to comments made by Barbara Welsh /Griffin, resident 1, 2, 3, 4. See Hearing Transcript Response #'s 15 -19 to Barb Welsh. 5. See Hearing Transcript, Response #26 to Robert Christensen. 6. See Hearing Transcript, Response #19 to Barb Welsh. 7. See revised chart in the Parks and Recreation section of the FEIS for corrected mileages. 229 City of Tukila In regard to the Environmetal Impact Statement for the proposed Valleyview Estates Development(File# EPIC - 205 -83). I take this opportunity to protest consideration of above project due to the past history of instability of the site and its potential effect on the propertiws above it. Due to the sesitive nature of the hillside any disruption in the drainage of water from the McMicken hill to the East may well trigger earthslides as far West 51st Ave. So. The marginal safety of the drainage system as provided by the State Transpotation Department is a critical safety valve for 464ft elim- ination of the underground water. However a malfunction of this system or an unusual flow of water absorbtion from the hillside above may create suff- icient pressure in the underground springs located on the westernmost property of Puget Western(Tax code 2052) resulting in earth displacement from east8blished residential properties between Slocum St. and 51st Ave. So. as evidenc a on my property located at 16030 51st. Ave ''o. During the twenty »four years I have lived at this address soil erosion has reduced the East side of my lawn by fifteen feet, coppletely covered a four ft. fence and partially covered the fence built over.the old one at the East 01111r- property line. Most of this erosion has occured since the pumps have been discontinued in the drainage system. I am enclosing slides and snapshots which show the size of the lawn from 1962 thru 1968 and a recent photo which is the current condition. Please return the pictures to me when you are thru with them. $Grandchildren grow up and these cannot be replaced) Thank you. Ethylmae H. 6030 Ave. So. i 231 Response to comments made by Ethylmae H. Cole, resident 1. The Earth and Water Sections of the FEIS and /or the GeoEngineers., Inc. geotechnical /hydrological report (Appendix A) has generally been modified to adequately include and /or address the concern raised by this comment on the DEIS. 232 January 26, 1985 ATTENTION: Mr. Bradley Collins Two questions. 1. Why did Don and Mabel Garen move from their home and property on 54th S. and Slade Way? * 2. What caused the rock slide on Klickitat Drive on Thanksgiving Day, November 22, 1984? Mildred R. Heppenstall 7 # 16615-59 Avenue South Seattle, Washington 98188 It is my understanding that the State of Washington forced them out because of slide conditions. 233 1 Response to comments made by Mildred Heppenstall, resident 1. It is believed the Garens moved from their property near 54th Avenue South and Slade Way in the early 1960's due to slide conditions and to facilitate implementation of remedial stabilization measures. 2. The cause and extent of the reported rock slide near the intersection of 53rd Avenue South and Klickitat Drive has not been determined, but it is not believed to be directly caused by or related to existing conditions at the subject site. 234 26 January, 1985 Bradley Collins Planning Director, City of Tukwila 6200 Southcenter Parkway Tukwila, Washington 98188 ;:2e: Draft Environmental Impact Statement Proposed Valley View Estates Condominium Dear Sir: As a health care professional, I am most concerned about the environmental health hazards and the threat to longterm community health inherent in the draft Environmental Impact Statement prepared for the proposed Valley View Estates. Professionally I object to the physical hazards posed by the unacceptable intrinsic noise environment throughout the proposed project site. Of equal concern, however, is the devastating impact that the unpredictable and uncon- trolled noise of construction, traffic, and daily living activities would have upon the viable single family areas adjacent to the property. In 1972 Congress passed the Noise Control Act, amended in 1978 by the Quiet Communities Act. This act is based on the following premises: uncontrolled noise can pose health hazards; major sources of noise are construction and transportation equipment, motors, engines or electrical equipment; and primary responsibility for noise control remains with the state and local government. This act also establishes standards and regulations concerning major sources of noise. Noise is a health hazard according to its level, freq- uency, and length of exposure. Depending on these three factors, noise reaction falls into the categories of annoyance, disruption of activity, loss of hearing, and physical or mental deterioration. Noise can affect a person's psychological and physical well- being. Physiolo- gical responses to noise include vasoconstriction of the peripheral blood vessels, slow and deep breathing, skele- tal muscle tension and galvanic skin responses. People exposed to loud noise of long duration have an increase in urinary output, an.increase in urinary catecholamines such as epinephrine, and an increase in blood pressure. 235 1 A major characteristic of environmental noise is unpre- dictability; noise often startles people, disrupting their physiological and pysychological stability. An annoying noise can aggravate existing physical disorders, disrupt sleep, lower the body's resistance to disease or physical stress, interrupt concentration, and generally disturb feelings of well- being. The greatest physiological effect of noise is temporary or permanent hearing loss. Temporary impairment, or aud- itory fatigue, occurs after a short exposure to some noise. Loss of hearing can occur at about 80 decibels (dB). Potential health problems of this magnitude cannot be ignored in a City who's goals include "gaining a reputation as the best and hopefully most admired City in the .State (Mayor Gary L. Van Dusen, January 21, 1985)." The US Environmental Protection Agency (EPA) has estab- lished standards and promulgates regulations concerning ma- jor sources of noise. It has described a noise level of 55 to 65 dB as a level where "adverse noise impact" exists. At levels of 65 to 70 dB, the EPA states that'Significant adverse noise impacts" exist; that these levels are "allow- able only in unusual cases where lower levels are clearly demonstrated not to be possible." At a noise level over 70 dB, "levels have unacceptable public health and welfare impacts." In a study paid for by the Valley View Estates project proponents and collected over a three day period in October, 1983, the noise level at one site upon the property in question was found to have maximum levels exceeding 70 dB during all 24 hours tested and exceeding 80 dB during the afternoon hours when people are most likely to be outside. In a second location the maximum noise level was above 70 dB during 10 of the 19 hours tested and above 80 dB during 6 of the 19 hour period; all 6 hours were during periods when people are most likely to be outside. This location was shielded by topographical material and the noise level was correspondingly reduced, according to the ET.- S EIS. On two other sites, adjacent to the property in the single family areas to the '.7est of the site, noise levels were measured above 70 dB during 20 of the 24 hour period on one site and 12 of the 24 hours measured on the second site. These same two sites experienced maximum noise levels above 80 dB during 5 and 1 hours respectively, once again during periods when people are most likely to be outside. 236 The maximum noise levels described are averaged to arrive at a day -night sound level figure (Ld ) which is the only acceptable level reading used by the tPA to form standards. The day -night sound levels in each of the four sites examined far exceeded the acceptable standards for noise. The Ld was 71.9 at the first site (EPA unacceptable noise), 64.5 at the second site (barely under the significant adverse noise level by EPA standards), 65.9 at the third site (above the EPA significant adverse noise level), and 63.4 at the fourth site (very close to the EPA defined signi- ficant adverse noise level). It is important to note that the noise levels were mea- sured during one period of the Fall of 1983. Folliage at that time would have still been present upon most of the trees, thereby reducing the overall noise level. Future increased I -5 traffic and subsequent increased noise was not accounted for nor projected in the 1983 study. The impact of the increased traffic to and from the project upon increasing the noise level was not given much weight when combined with I -5 noise, but still exceeded EPA standards. A more.thorpugh study under a variety of met- eorological conditions, seasons, times of day, with con- sideration for temperature, relative humidity, cloud cover, barometric pressures, increased vehicular traffic and utilizing varying sampling locations would be necessary to obtain data to predict the impact of the project site upon the environment, and thereby protray an accurate picture of the true noise level. Given the above information: first, that of the potential health consequences of noise; second, that of the EPA stan- dards in regard to noise; third, the number of times the maximum noise level exceeds 70 or even 80 dB, described as unacceptable in terms of health and welfare by the EPA, and the overall day -night sound levels at the proposed site which approach or surpass the EPA significant adverse noise impact standard; and finally the limited nature of the study in terms of typifying the intrinsic noise environment, it is important to closely examine the mitigating measures proposed in the EIS. 1. Interior noise levels. Conventional Northwest housing construction reduces noise.by about 25 dB. An additional 5 dB attenuation will be achieved through construction in order to meed [IUiD (not EPA) standards and will re- duce the total dB by about 30 dB. This would reduce the maximum noise level to only 50 dB, or 55 dB during certain periods of the day, the minimum level for avoiding speech interferance.and annoyance. Some of the periods of maximum noise in the October, 1983, study were at night when the desirable noise level for sleep would be even lower. ' :Vindows could not be opened as noise 237 levels would reach 65 dB or more (significant noise impact level by EPA standards and allowable only in unusual cases where lower levels are clearly demonstra- ted not be be possible). ': `ith.proper construction forced -air ventilation would be a necessity if problems due to poor air quality are to be avoided. However, one fact remains: EPA standards describe 55 dB as a situa- tion where adverse noise exists. The EPA also states that interior L should be 45 dB or less. These levels cannot benachsieved under the terms of this EIS. In this situation then, a health hazard would be unmitigated. Exterior noise levels on -site. 11 noise mi' �igati_on efforts have •been directed at limiting the interior noise levels with the exception of a proposed play- ground, partially protected from noise by an 8 foot fence which would "reduce the average noise levels by ,about 10 dBA to about 55 dB :A or less." - An average noise level of 55 clB is not an acceptable EPA standard. The acceptable standard, an L less than 55 dB, is a noise level where no adverse noise impact exists. The L v in the proposed playground area will exceed 55 d , even with the partial protec- tion during any of the hours that children normally play. '°ii tit ation - is inadequate in this regard. Not - - -ail- children will choose to play in the play - ground, perhaps preferring the recreation. areas not enclosed within the playground area. The 2300+ square feet of recreation area, identified in the EIS, must be the side yards between and around the buildings. These areas will be subjected to the high L noise levels of around 65 dB or greater. This 'his Elnnreport has made no mention of any mitigating circumstances regarding these recreational areas. - People do not spend all of their time at home indoors. Sunning, wailing, clipping grass, or simple conversa- tion outside will be affected by the high L,, of 65 dB or more. These types of social activity incTh.ich people normally engage will be putting these people at consid- erable long term health risk unless these unacceptable noise levels are mitigated. - Uncontrolled noise such as transportation equipment or other motors and engines will add to the already high noise levels in the area. This type of noise has been termed negligible in the EIS i but added to the 1 very high L would tend to force the noise level to- ward 70 dB higher. This futuristic consideration remains unmitigated. . Noise level changes off -site. The planning process for the City of Tukwila has allowed the formation of objectives and goals by way of the Tukwila Compre- hensive Plan which has been adopted by the City Council. Under General Goals, Section Three, 2esidence, Goal 1, residents of the area are assured that "Pleasantness and Integrity of Viable Single Family Areas will be Preserved." - The current noise levels in properties adjacent to the proposed Valley View Estates site have approached the 'adverse noise inpact' level, increasing each year since 1-5 was established, and demonstrated by the project proponentd study of the noise level on two sites adjacent to the proposed condominium site. A project of the magnitude of the one proposed in the EIS could not help but contribute to this environment- ally hazardous situation during the construction period, during the period of defoliation and elimination of the protective landscape, and in the future as increased traffic becomes a factor. This concept remains un- mitigated in the EIS. A "row of sycamore trees" will be all that separates the local single family areas from the inherent noise of the development and the in- trinsic freeway noise. Once growth of these trees is achieved, some years hence, and once the buildings are completed, the dB increase allowed by removal of the current growth is expected to be attenuated. This does not take into account the effect of the noise of some 200 people, their trips, and their daily living activities upon the Pleasantness and Integrity of the single family areas adjacent to the site. The welfare of the neighborhood remains unmitigated. 4.. General mitigating measures. The mitigating measures, while partially accepting the concept of hazardous noise levels both within each unit and outside, does not state with any degree of certainty and conviction that these measures will be instituted. "Should have... ", "could be reduced... ", "may be constructed... ", and "can be..." are phrases frequently used to describe construction measures and techniques to minimize internal noise. Stronger statements that describe what "will be..." done are few. External noise levels, on the other hand, "will be significant." ...And intolerable in terms of health and welfare. 239 1 From a community health.standpoint, I have reviewed the broad implications of this EIS. I have examined the health impacts of excessive noise levels, speaking for those who would live in the proposed condominium project as well as for those who live in the viable single family areas sur- rounding the site. I reexamined the EPA standards for noise, pointing out that the noise level on the proposed site ex- ceeds the acceptable EPA standards most of the time and reaches levels that have unacceptable public health and welfare impact during a large portion of the time. Finally I discussed the proposed.mitigation measures in terms of their inadequacy in addressing the physiological and psycho - logical ramifications of excessive noise. Let us review the questions that must be mitigated: 1. How does the proponent plan to address the problem of the dangerous noise health hazards where dB levels approach and surpass the 80 dB level where deafness occurs? 2. Flow does the proponent plan to protect the future own- ers from the physiological side effects of sustained noise at the "adverse noise" level such as hypertension, perpheral vascular effects, sleep deprivation and chronically elevated catecholamine levels? 3. How does the proponent plan to protect the resident children from the effects of long term exposure to noise which they will experience while outside and perhaps even inside and which will have life long impact? Lf • How can the proponent assure nearby single family areas that their rights have not been violated by the in- creased noise to unacceptable levels posed by traffic, construction, alteration in topographical structure, and other daily living activities? As a health care professional, I wish to express in the strongest terms possible my concern for the health of the people who would be affected by this project. I object to proceeding with this project unless provisions within the Noise Control Act and the Quiet Communities Act are met and provided for. Sincerely yours, Yikell :.i. Coe, R.N. , "n7 5112 So. 163 Place Tukwila, Thshington 98188 240 I11 12 I13 I14 Response to comments made by Mikell Goe, resident 1. Comments acknowledged. As noted on the second page of the comment letter, EPA's Noise Guidelines affecting residential activities apply to the day - night or Ldn measurement, which is the equivalent sound level over 24 -hours with a 10 dBA penalty applied to nighttime noise. The EPA criteria do not, strictly speaking, apply to other readings such as maximum noise levels. 2. Comments acknowledged. See the revised Noise section in the FEIS. 3. Trees on the site were bare when monitored as indicated in the discussion of Noise Level Changes Off -Site. As indicated in the introduction to the Noise section in the FEIS, "it can be expected that [these] documented noise levels will increase somewhat over time with expected increases in traffic volumes on I -5." 4. Comment acknowledged. As Table 6 in the FEIS indicated (Table 5 in the Draft EIS), an interior noise level of 45 Ldn can be achieved within all of the units as long as windows are closed. As indicated in the FEIS, maximum noise levels within units on the south portion of the site would periodi- cally reach 55 dBA or greater. As also noted, forced -air ventilation would be required so that windows could be kept shut and an acceptable day -night noise level maintained (i.e., 45 Ldn or below). 5. The EPA Guidelines specify that adverse impacts exist with an Ldn of 55 to 65 dBA. They also provide that the "lowest noise level [in this range] should be strived for." The Guidelines indicate that an Ldn below 55 dBA is "generally acceptable." The FEIS acknowledges that maximum noise levels within the children's play area will exceed 55 dBA. One potential miti- gating measure is relocation of the play area to the north portion of the site which would reduce noise levels by approximately another 3 dBA as has been proposed in the revised site plans. 6. The Draft EIS and Final EIS both indicate that exterior noise barriers could be constructed as a mitigating measure to reduce noise levels in outside recreation areas -- i.e., outside the children's play area. 7. As shown on Table 7 in the FEIS (Table 6 in the Draft EIS), traffic noise generated by the project will cause noise levels on adjacent streets to increase by an estimated 1 dBA. This amount of noise increase would not be noticeable. Freeway noise, which would not be affected by the project, would continue to be the predominant source of noise. 8. An indicated in the FEIS Noise section, long -term noise levels associated with the proposed project will not appreciably affect existing noise levels in the vicinity which are acknowledged to be high at the present time. Therefore, no mitigating measures are proposed to reduce long -term noise levels off -site. The FEIS indicates that noise levels during construction will periodically exceed existing noise levels in the area by 12 dBA which is a significant, though short -term impact. Measures to reduce construction noise include observance of State noise code regulations and use of equip- 241 ment with appropriate muffling devices. See revised response to Residence Goal 1 in the Plans and Policies section of the FEIS. 9. See the revised discussion of noise mitigating measures in the FEIS which segregates those measures currently proposed by the applicant from those additional measures which the City may deem appropriate as conditions of building permit issuance. 10. See the revised discussion of noise impacts in the FEIS, which addresses interior and exterior noise levels with respect to EPA's applicable Guidelines. Standards for acceptable noise levels would be exceeded in out - side areas not enclosed by protective fencing. Interior noise levels would generally meet EPA standards when windows were closed. 11. As indicated in the Human Health section of the FEIS, prolonged noise levels of over 80 dBA can result in hearing loss. While maximum noise levels on the project site will reach 80 dBA or above on several occasions during the day, project residents would not be exposed to continuous noise at these levels. 12. The proposed mitigating measures will provide exterior -to- interior noise attenuation of 30 dBA which will result in day -night interior noise levels of less than 45 Ldn which is EPA's recommended standard -- so long as win- dows are closed. The side effects mentioned are not considered likely to occur. 13. As indicated above, interior noise levels with windows closed would be brought to a generally acceptable level by mitigating measures proposed by the applicant. Noise within the fenced play area will be at the low end of the range where significant noise impacts occur (i.e., 55 dBA). A further reduction of 3 dBA could be achieved by relocating the play area as noted in the FEIS, as proposed in the revised site plan. 14. The Noise Study performed in connection with this project found that project traffic will not noticeably increase noise levels in the immediate vicinity. The significant noise impacts disclosed in the FEIS are impacts which would be experienced by project residents. 242 Bradley J. Collins City of Tukwila, Wn. Planning Department Dear Mr. Collins, January 25, 1985 At the time of the Public Hearing on Jan. 22, 1985, when the attached response was presented, we the undersigned, were unable to fully participate as we were not aware of the Public Hearing nor did we have knowledge of the EIS documentation. We, the undersigned, are residents of Tukwila. Most of us have attended the meetings in all the years past concerning the multi - family / single family issues. Our interests and concerns are definitely on record at city hall and with our elected officials. We are not in view of the construction sight from our homes but our daily living would assuredly be affected by this project. All of us drive the streets that would be affected by the traffic impact made by this project. Our homes would be affected by the traffic conjestion and noise. The safety of our street connected with 54th. Ave., Slade Way, 166th.,160th. and Klicitat Drive has long been a concern even as the traffic issue is at present. After having the opportunity to briefly review the EIS document and hearing the responses given by concerned residents in the area, We the undersigned, believe all issues presented to you at the •Public Hearing of Jan. 22 (those listed on the attached letter and those proclaimed at the hearing by all participants) should be seriously considered as very important valid concerns of the residents of this community and you, in your /our city for the present and future. The fact that we have been overlooked as having a special interest in this issue we are requesting our names be registered in your department at City Hall so that we would receive any future notices or documents pertinent to this project or issue. Sincerely, .44Z4 dt Ruth I. Hayes 243 Response to comments made by Ruth Hayes, resident - Comments acknowledged - 244 January 24, 1985 Mr. Brad Collins TulFwila Planning Director Tukwila City Hall Tukwila, Wash. Dear Sir: I read the article in the January 9 issue of the Seattle Times and I am puzzled as to why you did not mention the nroNosed 1 development of condominiums on Slade Way at the meeting on January 8 at the McMicken Heights Clubhouse. I originally moved to this area 35 years ago to be away from an urban atmcsnhere and that is still my reason for being here. I•m sure my feeble protests will in no way stop this thing from going in, but I do want you to know there are those in this area who vehemently oppose it. Sincerely, (emadazob (Mrs. H.F. Do .ms) 245 Response to comments made by Mrs. H. F. Dohms, resident There was some discussion about the City of Tukwila land use policies and recent changes in the zoning for the McMicken area. Discussion about site specific proposed actions was in response to questions by the audience. The City has no record of whether this specific development was discussed or not. 246 From 54th Ave. S.-West on S. 166th e_eivr//va /Ncr— On 53rd S. to4l 70th This area wab canvassed and following are the results: 44 signed 2 away on vacation 1 too ill to sign (had a chemotherapy treatment the preceding day) 2 did not sign (in City of Tukwila Gov't) 2 did not sign v,4nr 4/ / y 2 A:4 Lew f_s Vc;N� g i? h' D IiEs, A./.54.5 ro 77746 DX/H=7- Cat.) Ui A) .06(.4-4 G //,7/ ,— 5,77116: Ax= v , 4 vcFai -- 'J?/ o /g et2v.0 7 /,u /7 C/.v /% S ©.v ,7/6 //i / /s/D 8a -oza M-6 `' 6�`/ /L .o6 6,/gc.e 4 && is & 6x., //e/70A) a287,,, i 6 , '9 A' 4-rc; Gv /// "4-5: 4 a ' i vc; 3,M/1-y1 ,�/1 -,v "/V i Y7h eery 17 -4C, aDULD Tw /1e/75117- 771/S i / / /5/ /.0o,e ic X)a pwe ,65/i7DA), :Cc 45 ' 1r� /c iboc G7-/. ,, woicO Yo e./ lac/Ye S; t; 771/) Silee G ,i,7/ your ,4 o/2gr =s5 S, Pt-G:456 ,477E/'D 77/� ,,fS /,6495. NAM A/1,a.. 7/Y). c_TA.e.e4 ile-ya,a 7MVX yo Avg Be IMIA2 4DDiaE5.5 CY fA0(o a �so OD 10 - nc �� It 53A • geo h /310 &S) S )U E5 X-1•47 PO) -17'")*A.0-1041, LM,V2 72 7 -y4j'z ve / 7, )97 - 77/ 7#75(-- q77V°,:iY(‘.", Sc9daY avvV Response to comments made by Petition from Area Residents - No response required - 251 RESPONSIBLE OFFICIAL'S, COMMENTS .'VALLEY VIEW ESTATES January 22,_ 1985- RESPONSIBLE OFFICIAL: This is a public hearing of the Draft Environmental Impact Statement for Valley View Estates, January 22, 1985. Tonight we are going to be reviewing any procedural questions that you might have for the Draft Environmental Impact Statement or the review process, but we will not be answering any other kind of questions for the response to information requests, or comments we would have during the Final Environmental Impact Statement process. So our process tonight is to listen and record comments and not to try to answer questions that you may have except for as they deal with procedures. I am Brad Collins, the Planning Director for the City of Tukwila and I am also the SEPA Responsible Official 4'` authority using the RCW's to conduct the Hearing tonight to give everyone an opportunity to comment on the Environmental Impact Statement. You might note, as does the Environmental Impact Statement, that there has been a change in SEPA regulations that have occurred since the onset of this process, so the DEIS was done under the old SEPA regulations and the format for the review process and the subsequent handling of the EIS's is being done under the new procedures which were adopted by the State effective April 4, 1984 and adopted by the City effective the end of September, 1984. Your oral comments that you give tonight will be responded to in the same manner as written comments received or. the deadline which is the 27th of January. Any comments are postmarked a January 27th will also be responded to. With that, I would like to start out with any questions about the Public Hearing's procedures tonight. If people have any questions regarding how the Hearing is being conducted, please step forward to the microphone and go ahead and ask your questions about tonights Hearing, and then we will take the sign up sheet and begin our process of collecting comments on the DEIS. Is there anyone who has any questions about the Hearing tonight? 0 Dick Goe: ... Could you, Mr. Collins please advise the entire audienceAthe procedures that will be used tonight in terms of their opportunity to speak,`` present written material, to ask and get questions answered, and if there^b'e any limitations on the time, they will be allowed to speak or deal with an issue. Whether or not the p zo,ject proponent is hear to answer questions, or whether you will be doing,1on behalf of the project proponent. And then, if you would, advise the members of the audience what the entire EIS process is from the beginning, the time of the inception of this draft until the completion of the process that might allow the proponent of this project to file for building permit and get that permit granted... RESPONSIBLE OFFICIAL.... I will try to be brief and if I miss any of the questions you've asked please remind me and I'113'4t7"").6"First of all, the process for tonights meeting is that we will invite people to speak from the signup sheet and you will be able to provide your written testimony as well as your oral testimony tonight and that can be submitted to the Planning Department staff people who are located in the table in front of me. If you want to 253 use the overhead projector or other means we will have that available to youlghow that kind of information. We have not set any time limits for the individuals chance tc'inments. We ask that people be to the point, because there is a lot of people here and everyone wishes to talk, we could be here quite late tonight. We would ask that if you have given testimony that we will ask that you wait until everyone has had a chance to provide initial testimony before we ask the person to come back up to the . microphone and give further testimony. We are not limiting the testimony to one's time at the microphone, but you will be asked to wait until everyone else has completed their first round of testimony before you give any more. The procedure that we are following as far as what is an Environmental Impact Statement, the document that we are reviewing tonight is referred to as the Draft Environmental Impact Statement. Under this SEPA, this ANS circulated to agencies with jurisdiction or interest, and individuals that have expressed an interest, the distribution list for this document is identified in��,,,,,,��l inning of it, and it is also available to the general atwsc public. It �s,�'nrou h the�,la n' g Department, and is also available in libraries and vlch res ± ttbl &cal n wi apers that this document was available. The procedure, oncA an EIS is published, is that there is a 30 day comment period. After that 30 days, those comments are collected, the written and verbal comments in this stage because we have a public hearing are collected and reviewed as to the accuracy of the EIS. The Responsible Official will make a decision as to whether to respond via a revised DEIS, known as a Supplemental DEIS, or respond to the questions and comments in a Final EIS. Once the Draft or Supplemental Draft EIS process is completed, those comments that have been received on those documents, are put together and the Final EIS, together with the response o the City and the Applicant, to try to answer those �'`�t� pp y questions or the tat have been expressed. The Final EIS is then recirculated to the people in the Distribution list of the Draft EIS an • 7 days have to occur following the publication of the Final EIS before W subsequent action onity's par"; in this case, we are reviewing a application for a building permit. It will also, I believe, involy review before the Board of Architectural Review and a decision ��needed building permit or the Board of Architectural Review ex that 7 day5has elapsed. (I:C. A t,t a + o c.0 "-c. + The question of whether there will be some kind of questions you have an opportunity to answer tonight, we will not be trying to answer substantive questions. The information that is in the document;°`Yrring to verify this information. We will try to answer any procedural questions you have. Those kind of questions that are raised, we will try to respond to in the Final EIS. You are also called on to contact the Planning Department and the applicant that is listed in the Draft EIS to get further clarification, questions that you might have regardi the information that is in there. But tonight's meeting will not be a ` between the applicants and peoples creating comments on the EIS. The applicants are here and they are here to listen to comments, because they are going to be responding to those comments in the Final EIS. What are some of the other questions that you felt ?.... 254 Dick Goe...Well, once you deal with the Draft, the comments that are dealt with here tonight, you will be proceeding with that, that couz he Final EIS. At that time, you have to make a decision based on the accuracy of the information submitted. What process is available then for the citizens to monitor the actions from that point on? How do we keep tabs of what is happening ?.. RESPONSIBLE OFFICIAL... I will try to define your question, "What happens what citizens can do following the response of the Public Official, the Responsible Official on Draft EIS comments and on publishing a Final EIS ?" Once the City has made a decision as to the adequacy of the Draft, and has X published a Final Environmental Impact Statement, if there is disagreement on the part of people that have commented on the adequacy of that, that can be appealed to the City Council. So any decision made by the staff, myself acting as Responsible Official, is appealable to a City Council and subsequent to their review and decision on the , is o the court.. In terms of what happens after the Final EIS and any further appeal, once the environmental review process has been completed, the City will move towards the substantive decision on the application for a building permit, first through the Board ofciitte�etural Review and the decision on what kind of conc�tions might be app fr,.oval for architectural review and then onto 1r issuIllep or denial or a conditioning of'-building permit based on the revie`? ilding permit for the various information contained in the environmental review document. The process has certain built -in time frames which th citizenry can react to each: on the way, so that is the reason fora delay after the publishing of the EIS for action can be taken. Are there any other questions ?... pick Goe...I have the questions � the benefit of everyone in the audience and to make sure, on a part of all the citizens here tonight, the best understanding we can of the process, because, as you point out some place in this document, rules have changed and I think it is only fair that we be kept abreast of what they are, and know what the process is so we can keep up with as it goes along. SoIwould appreciate your review of that, and I hope the rest of the people as well. Thank you. RESPONSIBLE OFFICIAL... Do any of you have any procedural questions? Eleanor McLester...I hope it is a procedural question. As we go through this process of commenting on the Environmental Impact Statement, and going over any corrections, additions, deletions, revisions to this. When we finally get down to the road to where there is a building permit issued eria.40L development of this magnitude begins to take place, I would like you to go a little bit for the people who are sitting out here , in what we as citizens in that area can do to see that people live up to the intent that was presented to the citizens, because I have lived here for 20 years. I have watched EIS's come in, I have watched us comment. I have watched grandiose plans presented and I have seen pieces of junk built on the hill in my city. I did a tour this Sunday to go up and take a look at things that I don't think our building and planning department have ought to have 255 allowed to get by. We build junk in Tukwila and we allow it to be built. Can you tell us how we can help monitor the "after process" if it gets that far, so that we don't feel we are totally helpless in what goes in in our neighborhood? RESPONSIBLE OFFICIAL: I will try to be very brief and note that is really not a procedural question brought to tonight's hearing. Eleanor McLester...But it is certainly on the minds... RESPONSIBLE OFFICIAL: I will try to briefly answer your question. In terms of keeping the City official5responsible, basically you need to communicate not onlyyour elected officials but the staff of professional officials that there is something happening which you do not believewhat was required under the law. Obviously, if any official of the City doesn't meet the requirements that are set forth, then those actions are subject to challenge. The primary concern that you have, is how you keep your City officials responsive to citizen needs, and the only thing that I can say is communicate with them. There is no set procedure. Eleanor McLester...We have discovered over the years, that things get cut down, grades get changed, and it is literally done before any of our officials can get in there and stop it. Now citizens are not usually allowed to wander around the construction sites at will. And quite frankly, the City officials cannot spend every minute of every day up there monitoring every cut with the bulldozer and that kind of thing either. So, it is a concern to us. RESPONSIBLE OFFICIAL: Ma'am, as a City official I share your concern to develop the same issues. O.K. Are there any other procedural questions about tonight's Hearing? If not, we will move to the first page of the sign up sheet. Herb Phalan: Yes. Good evening. First of all are we going to get a record of these proceedings? RESPONSIBLE OFFICIAL: There will be a EIS, a paraphrasing of com.,mw�n ,,ts that are received tonight, and a response on part of the applicants` 3`the City to those comments. There is not going to be a transcript of the meeting made, but rather the comments will be paraphrased in the Final EIS. Herb, Phalan...It would then be available if wanted it, if we came here and asked for a copy of the minutes of the meeting, for example? RESPONSIBLE OFFIAL: wit 'W4€ I bell ve that4won't have a transcript,[.a�• someone is willing to Lail a cost the transcript, that will be getting a transcript of tonight's comments. 256 Herb Phalan...I actually hadn't intended to speak tonight. That signup list was merely to indicate those people who attended the meeting, and I think you will find that's the case with many of the others here too. I would only like to add my testimony to Mrs. MoCluster's. As she says, we have been here for twenty years trying to keep these developers at arms lengths and keep them off the hill and keep them from what we consider to be degrading our neighborhood. The degradation takes the form of what I believe will be eventually become low- income housing because of the particular area that these apartments are going to be built in. I can't imagine anybody with any financial resources wanting to live in that particular little corner overlooking that freeway with all that noise. So that the congestion, the traffic, the hazards from building on the steep slopes, such as that one, are all our concerns. Now I think that Mr. Go and Mr. Crane and later are going to provide you with some more detailed information, and I hope that you will take each one of the points that they have and address them very seriously and consider them. Thank you. RESPONSIBLE OFFICIAL: The next speaker is Ethel Mae Cole, 16030 51st Avenue South. Ethel Mae Cole: Well I sent my slip in and I hope you read it. The main thing that I worry about is the fact that those hills up there above them are slipping and slipping badly. I have lost 17 feet of lawn in the last 20 years. It just goes down that hill very easily all the time. Down at the base of my hill, next to Mr. Solem's place, if you get up there and do a little digging around, you would find 2 four foot fences that have been completely buried. The result of it is, that I.had a real nice big lawn and everytime something happens to that hill, I lose a bit of it. And sooner or later I am not even going to have a house on that hill, because I have got about 5 foot of lawn left. If it doesn't get stopped pretty soon, I am going to have to move. And personally, I can't afford to. And besides that, it isn't going to help anybody on the hill there to have all those houses sliding. If mine slides, there is going to be whole handful of them slide. And there is nothing going to stop them if they keep moving things around. About one more bulldozer on that hill and there goes another piece of landscape. And it has been doing that right along. When the State had the pumps going to keep the hill dry, there was very little slippage. But when they got their intersection in and shut the pumps off, it went right back to what it was before. That hill, all the impact statements in the world could tell you nothing about it except that it is sand. And it is just sand over top of clay. And it is slick underneath. And everytime that there is a least little bit of ajar, or anything else, even an earthquake starts that to slippin' and I don't believe we need a whole group of houses diked down underneath us stirring things up and they will not build anything down there I am sure without putting bulldozers and everything else in there. RESPONSIBLE OFFICIAL: The next speaker is Fred Bigelow 5207 South 16ZIth. Fred Bigelow: Well I also thought it was an intended sheet. But I did want to know what the procedure is, so one could get a copy of these statement. Because apparently I was not on the distribution list even though I live in the neighborhood there. 257 RESPONSIBLE OFFICIAL: We do have copies available tonight. You can go xo the Tukwila library or the King County library at 178th Street in `4W44'to QOriew them there. We have copies in our office to beRriewed. If you wish to pure se a copy, it is rather an expensive $13.50 I believe, and the � ` of the distribution list was, I recall, a 300 foot property list as well as people that have expressed interest at previous Hearings on this particular project. Sorry you were not on the list, but we do have copies available. If you don't wish to purchase one, there are several locations where there can be checked out and read. Fred Bigelow: Someone wants to know if I can get on the list for the rest of these distributions. RESPONSIBLE OFFICIAL: I think that is possible. The people who make comments will be advised to put them on the list for the Final EIS. The next speaker is: Darlene West 5212 South 164th. Darlene West...For 20 years, probably my 200th appearance. I have quite a few questions. I don't understand why there is any possibility that they can consider building on top of a sewer line even if it doesn't belong to the City of Tukwila and even if Val -Vue says "Oh, that's ok, we don't care ". Because when we got our building permit we were informed that you cannot build over sewer lines, storm drain lines, water lines, any other type of easement for anything like that. So why should they be so privileged when the rest of us aren't? Legal is legal. They say that you can put 21 single - family homes in that area. But that that's not practical because developing the property would price it too high. It would be over its market value. But they haven't given us any figures. I would like to know what they consider market value. Also, they say that the projects that they could do for reducing the noise impact inside the apartment condos, might also price the units too high for many who would like to live there. Sounds like the same thing. Also, there is a road project planned there for 1987 -88. If the project paid for that, would that price those condo units over market value? And if it didn't pay for it, would that discourage people from buying them, because they would have to pay for it in the next couple of years when a L.I.D. was formed? When they mentioned the height of buildings being 20 feet below the top most part of their building, being 20 feet below other buildings in the area so that they wouldn't block views, have they considered future homes along Slade Way? There is a lot of vacant property there. Have they considered the placement where they might possibly be and would it still be 20 feet below since they say it's going to be 30 feet above Slade Way. One piece of this property is zoned R -1 and was zoned R -1 when they applied for the original building permit. Then why can they use that space when they are considering their percentages and the area that is left open and so on. It doesn't seem logical that they should be able to use what even they admit is R -1 zoning when they consider the total area. It seems that they shouldn't be allowed to count that at all in their multiple zoning area. Also, since there is a special setback from R -1 zoning to Multiple 258 Zoning when you put in a building next to it, then is there a setback far enough away from the R -1 zone section of the property? It seems that it wouldn't really matter whether they happen to own all that property or not. The setbacks should still be the same from the R -1 zoning. Because otherwise, if you have multiple zoning, if you just buy some R -1 around it, and build right up to the property line of your original piece which is defeating the purpose of the laws. Also, since on the R -1 zone, they show absolutely no structures of any kind. Does that mean that they are agreeing never to develop that piece of property with any structures at all? If they get a building permit, would they have to build exactly as proposed in this EIS, or can they just put anything they feel like on there? There going to put a total of 182 parking spots for 108 units. Which really isn't very much when you consider most cou����l,,�e , whether they are both working or not, have two cars. That would�v3r-tually nothing for company, except of course the road which they keep saying , "except for very special social occasions" would not be used. They also state that certain driving and parking areas may be declared "fire lane, no parking ". So how many parking spaces are they going to lose that way out of this 182 that really isn't sufficient to start with? Also, they say that there will be an increase of 90 vehicles during the early evening peak hours, but it won't be a significant change. 90 vehicles on one hour on that street would definitely be a significant change. It would be a significant change for the intersection also. According to this EIS, 53rd Avenue South now has 2200 vehicles per day. They state they will increase that by 900 per day. That is 41%. Now that is a big increase. I don't see how they can say that it is insignificant. They projected figures for 1987, and on the page that where they show this projection, they only show 530 more vehicles movements on 53rd from north of 158th. They don't show what is going to be south of 158th on 53rd Avenue. What happened to the rest of those cars? Did they just sort of straight up or what? They also show that the Slade Way's present volume is 90 -110. They say that three quarters of the 900 will exit on 53rd and a quarter will exit on Slade Way. Even at those rates, that's 31% increase on 53rd, and 250% on Slade Way, which even they say is very narrow and not in good shape at that particular part of the road. An awful lot of those people who are going to come out on Slade Way anyway, are also going to come down on 53rd to get down into the valley. So they are ending up there and making that 31% increase even higher. They also say there is only 25% increase for left turns from Klickitat to 53rd Avenue South. They haven't addressed left turns from 53rd to Klickitat. I mean you .know, people do go both ways. They don't all turn right down there. I can guarantee that. Thank you. RESPONSIBLE OFFICIAL: The next speaker is Dennis L. Robertson 16038 48th Avenue South. Dennis Robertson...I would like to speak on two issues. One on Page 36 where it talks about neighborhood objectives and policies. OBJECTIVE #1: "Protect all viable residential neighborhoods from intrusion by incompatible land uses." The comment from the EIS -- "Project development will occur as a result of vesting of rights prior to the effective date of the current zoning ordinance. All other properties in the vicinity is subject to the current zoning ordinance and therefore will remain zoned for 259 single family development." Then it goes on and talks about Mitigating Measures. Well this implies that once something is zoned something, it will stay that way forever. Obviously, that is not true. Comprehensive Plans and land uses have an average life of perhaps ten years at the longest. The current plan has been in the works, for it seem almost that long, at least it has been here that often. But it won't last forever. Once this property is developed, as a condominium. What is going to happen, is that there are other large tracts of land immediately to the west. I think to the north and to the south. What is going to happen there is is that those properties are very Olikely to develop. They haven't yet for a variety of reasons. Probably the same reason this one shouldn't develop. In any case, they probably won't develop single family homes, no matter if they are zoned that way, because they'll be developing next to an apartment. It would be very difficult in that environment there to sell anybody on buying a house which just got put up next to a three story apartments and condominiums. It will stay undeveloped. We will see tremendous pressure to rezone that and to change the comprehensive plan. Eventually the plan will have to be reworked, as they all are, because no plan lasts forever, no does zoning. At that point, when it's changed, the mere existence of this development will be an overwhelming factor in seeing to it,that we see more development down near apartments and condominiums. So their argument that the fact that all of the others is currently zoned single family doesn't mitigate the fact that this non - conforming use would indeed eventually change the other property. It would be the main reason. The single reason we don't have apartments on that hillside right now, is because there aren't any. We haven't seen any new ones built for a long time, because there aren't any there next to it. Meeting after meeting, with both King County and Tukwila, the main argument for putting an apartment in one place is that there is an apartment across the street or next door to it. So what I am saying is is that this particular mitigation is indeed not a mitigation. It may delay things for several years, but it only delays it for a while. The next point I would like to deal with is on page 60. I am an engineer and I have a concern about engineering facts. The way the engineering and geological data is presented here each item is allowed to stand on its own. Well, that may be the case when we are talking about subjective things. But when you are talking about things that are related to safety and engineering you have to take a look at the whole thing. I didn't see any kind of analysis when one looked at a risk analysis of the whole thing sliding over that way. On page 60 it talks about mitigating measures for the geology. It says, "all recommendations contained within the geotechnical report will be complied with by the Project Sponsor, including the following summarized below:" Then it goes on to list six different things that have to occur. Any one of them doesn't occur as listed here, that property has a significant risk of sliding away. What we are talking about is 108 units, with probably two or more people in each one. If that thing slides away in the middle of the night, there are several hundred dead people. That is not a trivial issue. To take each one of these by itself is one thing. But what it really is, is a probability that each will occur. For instance, the drain fields. The drainfields were designed for a 10 year storm. What that means is, is that there is a probability within a 10 year period with certain competence interval, that that storm will occur. The same thing with there is a probability that the drainfields will work, that they would design right, 260 12 13 that they will break. There is a probability associated with the sewer line that it won't break and slide away. There is a probability that associated with maintenance of the drainfields in the french drains by the homeowners association. Each one of those may be a probability of 99 or 98% success that it will work. But the way you analyze the whole project was a slide could come from any one of those is to take each one of those probabilities and multiply them times each other. So the overall probability of that being a successful development over the next 30 years, meaning that nobody gets killed, a mass disaster, is each probability with success multiplied by itself. One has to look at the whole project. This EIS does not do that from a geological sense, or an engineering sense. It looks at each one independently. Yet the engineers say that each one has to occur. So one analyzes the safety factor, the environmental impact, how does the environment impact this development? In this case the risk of several hundred people being killed, has too look as a whole project, and I don't see any kind of a really significant risk analysis or no concept at looking at the whole report as a whole in this kind of a sense. I think the report is totally deficient in that sense. There is a gigantic safety risk here and that is not dealt with , other than the mention that the financial institutes will probably charge a higher interest rate that the insurance will charge a higher rate. That is an admission right there. Yet they don't deal with that. I see no analysis what could occur, what the probability is, especially as a whole project. I think it ought to be sent back and worked over again. We ought to know, and then by the way, 1 haven't seen anybody's willingness to say, "hey, 'I want a 90 %, I want a 95% guarantee of success of what kind of a _ Well, 99? If I was buying a house for my family I know what I would want. I have been in a couple of slides in my life, and they are not a whole lot of fun. What risks does the City stand? If the City oks the Environmental Impact Statement it gets built 5 years later. If something goes wrong, let's say the Homeowner's Association doesn't maintain your French drainfield, or they don't know how to read a feasiometer? (I don't know how to say that) and it slides away. Who's at risk? Who pays? Who gets sued? Those with the deepest pocket probably. That is likely the City. Where will the developer be at that point. This is not a typical development. This has extremely high risk. This EIS doesn't deal with that at all. RESPONSIBLE OFFICIAL: The next speaker is Barb Welsh. 5113 South 163rd Place. Barb Welsh...As a concerned property owner and a mother of our future, I am very concerned about the inconsistency and inaccuracy of this Draft EIS. I don't know anything about the engineering aspects of it. I don't know how a cable crosses the middle of the road, but the little box can determine how many vehicles go up and down a street in 1987 or 1988. But I do know a couple of points that is very concerning to me. One is the amount of parking. With a 108 unit complex, there is not ample parking. The developer is allowing 1.5 spaces per dwelling where the police report dated suggested to. "Buildings 1 and 2 only indicates on the maps 9 spaces for 12 units with no overflow parking." To me, all the overflow parking will probably park on Slade Way, which is much close than 261 the design overflow lot. The street parking then will result in a serious hazard to everyone around because the street is narrow, there is no shoulders, there is a dangerous curve and the grade. And that would increase accidents and vandalism. Also building 3 to 18 doesn't have enough parking either. For example, on my street alone, which is 163rd Place, there is thirteen houses, four with children of school age. There is 40 licensed vehicles on that street everyday and that is an average of 3.07 per house. Per Figure 3, buildings 14, 15 and 16 is one concern of mine that upsets me very much. They say it is going to be especially equipped for handicapped people. To me a handicapped person in a design apartment means it is for a wheelchair person. There is inconsistency with the 1.5 stalls per unit allowed. According to the figures, they are only allowing four handicapped parking stalls for 6 handicapped units. There is no provisions for sidewalks for the handicapped, there is no provisions for guest parking of regular guests who are handicapped and there is no provision for a handicapped mother to go to the children's play. area to watch her children play. They are only indicating steps. There is another thing that bothers me very badly. It is the schools. There is repeated mention of approximately 27 school aged children attending Tyee, Chinook, Bow Lake and Valley View. According to Jim Mask, of the Highlines School District Transportation Division, this area where this complex is being proposed is located in the McMicken Heights Elementary School boundaries. Not Bow Lake, not Valley View. There is not one word in this impact statement showing what impact those children will have at McMicken. Another thing bothers me very badly. It's how are these 27 school aged children going to get to school? They are going to have to walk up 160th to catch the school bus. According to Mr. Mask there will be no rerouting of the school bus down to Slade Way and 53rd Avenue South. For multiple reasons: 1. There is no safe means for that bus to turn around at the bottom of the hill. They will not travel on 54th due to the fact that it is a one -way road. There is no turnaround in the complex, because it is private property with speed bumps, and that is not a direct route to and from school without eliminating all the stops on 51st and the 51st kids have priority because they were first. Due to the icy and snowy conditions where the school bus schedule goes into effect, the children will be walking up to 164th and Military Road to catch the School Bus. Which brings me to my next point: The conditions the roads. According to page 100, the roads in the immediate area "two lanes in fair to good condition with some local exceptions to potholes and /or poor pavement." Shoulder width is indicated is not narrow. What is not narrow? 160th between 51st and 53rd, north of the present Metro bus stop, the shoulder width is 2 feet or less with the dropoff. Is this adequate walkway for the safety of our children? On Slade Way, just below the top of the hill, the shoulder width is again 2 -3 feet. Is this adequate for safe off -road parking. According to the Public Works Department, that is to be under a L.I.D. program. And what I understand the L.I.D. program to be, is those streets are not up to City standards. And in order for a project to be built, they have to be upgraded to meet that standard. That means the developer will have to pay to have those streets updated. And with the 262 project increase of vehicle traffic at the entrance to the complex on 160th, 3.67 vehicles per minute and 160th between 51st and 53rd, 3.5 vehicles per minute. Will you allow a child to walk up 160th with that amount of traffic? And would you also allow a child to walk to and from the recreation facilities? Some of these children will be leaving and /or arriving home at dark. How can they safely cross 160th at 51st, 53rd or Slade Way with no stop signs, no stop light, crosswalks, overpasses or even adequate walkways of the shoulders? The inaccuracy of this report really bothers me. Because the recreation facilities which they mention in this Draft on page 121, is another point. For example, last Saturday I went out for a ride to check the mileage, an like Thorndyke, they said it's .4 miles for the site. Actually, it is 1.6 miles. For another example, Tyee - -they say it's 1.5 miles. Actually, it is 3.2. Now if I can find with just a high school education, these inaccuracies of this Statement, I honestly believe the engineering aspects is also incorrect and all the information that they are giving us is incorrect. And I think it should be revised and updated and corrected before any more comments are made. Thank you. RESPONSIBLE OFFICIAL: The next speaker is Robert Crane. 5105 South 163rd Place. Robert Crane...Many of things that I will be mentioning here have already been mentione by other speakers, but with everyone's indulgence I'll read the material I have. Incidentally, I was surprised to hear that the price of the Impact. Statements were $13.50 when on the cover the word "Environmental" is misspelled. I just didn't sound like that expensive a document. The material I am reading has been prepared with myself and Richard Go, along with inputs from other residents. Dear Bradley: This is prepared for submission in a written form to you. The Draft Environmental Impact Statement for the Valley View Estates has been reviewed by the citizens below and has been found to be seriously flawed in many areas. Our major concerns are listed on the following pages. We are also especially concerned because of the obvious high safety risk inherent in this project. This proposed development would place over 200 condominium residents in grave danger if one of fair four likely events were to occur. The State Department of Highways, Drains and /or pumps fail, the condominium drains fail, a rain storm greater than a 10 year average should occur, or sewer line leaks or breaks beneath the building. Any one of the above listed events could easily result in a landslide that could be a very large disaster. Aside from the immense moral implications, what would be the City of Tukwila's liability if it was to approve this development as environmentally sound? As City residents, we strongly urge the City to require an adequate EIS showing the real impacts And now I would like to address the EIS statement itself. On page 26, under "Natural Environment - Goal 1 ". This development 263 19 20 21 requires too many spacial conditions to be a suitable development for its natural environment. It is not safe unless the State's pumps and drains are working 100 %, the sewer line never leaks, the new French drains are perfectly maintained and the calculations for the building structures are proofed. On page 29 under "Residents- Goal 1 ". This development would destroy not protect the integrity of the single family area. It is a highly visible, large 7 acre development located at the entrance of the single family area. "Goal 2 ". This development would be the first multi - family one in a single family area. It is true the current zoning and comprehensive plans show the area as single family. However, owners of other large, undeveloped sites near it would use the argument of its existence and impact on them to successfully argue in favor of higher density zoning in future years. As such, this development would have a significant impact that would eventually change and destroy the single family area. On page 32, "Policy 1 ". Discourage development on slopes in excess of 20 %. It appears on the map that almost 60% of this property is over 20% of slope. The argument that it is improbable that the site would remain undeveloped unless acquired by the City is meaningless. The City has not owned it to date, and it is undeveloped just as it is-- unstable, and over 20% in slope. It may be a bad investment risk as condominium property, but that is an entirely different issue. On page 33, "Objective - Clean Environment." If the proposed site would be unhealthy because of .three -way air pollution, how can this goal be met? On page 34, "Policy 1 - Unstable Slopes." The slopes will be stable, only if all of the sewage and drainage facilities work perfectly. If not, it is a very dangerous development. On page 36, "Objective 1 - Incompatible Uses." The leading part of the brush on the hillside does not mitigate against the fact that this is the first multi - family development in a viable, single- family area. Also, as stated before, zoning laws and comprehensive plans are regularly changed and the existence of the proposed development would be a very strong argument for a multi - family zoning and adjacent properties. On page 37, "Objective 2 - Minimize Incompatibilities ". The proposed development will be the first thing sees when one enters the neighborhood. Its very existence will change the neighborhood. On page 37, "Policy 1 - Transition Areas." The freeway is the transition buffer area between the neighborhood and Southcenter. The fact that steep gradient exists is a fact for the whole neighborhood and does not create the buffer, it merely creates an unstable slope. On page 47, "Policy 3 - Storm water." The use of a ten year storm criteria for this development is considered insufficient based on its history of instability. On page 60, "Mitigating Measures ". How can the proponents of this development honestly guarantee that all six measures will be successful? The State Department of Transportation will clearly not guarantee No. 1. 264 21 The second measures requires a Homeowners Association to be responsible. The City clearly understands how difficult it is to get its associations to be responsible for repairing roads and cutting grass, let alone something like cleaning sewers and drains. On page 72, "Mitigating Measures ". A ten year storm drain is not sufficient for this steep of slope as mentioned before. On page 75, "Impacts ". The second paragraph dealing with the control of the artesian pressure and the reliance on the State Department of Transportation. for maintenance of their drainage systems, is enough to refuse the development, even if the State agreed to its responsibility. Several hundred lives are at stake. On pages 126, and 127 "Unavoidable Adverse Impacts ". The City would have to allow the placement of buildings over sewer lines, something does not normally do. But on such a steep unstable slope, while would the City allow such a dangerous precedence? On page 145 "Economic Factors ". The financial loss to the city of residential housing would be significantly less if this site was developed in a single family area. Page 149. "Short Term and Long Term ". .The alternative development of the site as a single family area is ignored. Page 121. "Parks and Recreation." As noted before, the mileage shown to various recreation areas are basically incorrect and the entire page showing distances appear to be in error by about one -half. Page 126. "Drainage and Instability." The present hillside drainage system is approximately 20 years old. If the above ground pipes are leaking, does this not indicate the entire system is possibly marginal in its condition? Was this system not designed to counter slide in drainage problems with the hillside 'in approximately the same condition that . it is in today, and if so, would it be adequate with the stress that this development would place on the hillside? Pages 141 -142. "Pollution ". We believe the dense growing vegetation from the hillside is an effective screen from auto - polluted air generated from Southcenter and I -5, much of which will be loss with this development. Page 151. "Alternatives ". The conclusion of the EIS the continuation of the property in its present state is highly improbable unless acquired by the City is not backed by any facts. As individuals, we believe in the rights of investors to a reasonable return on investments. We believe the proponents took a known risk in this investment, and a development which appears to have strong negative effects on the neighborhood is not in the best interest of the public. Page 91. "Land Use." The EIS indicates that liability insurance companies and lending institutions are unlikely to be supportive of this project due to unstable slope potential. It is felt that prior to approval of this building permit, the developer should be required to post two bonds. One bond would ensure that during construction, should the project to be found 7265 unfeasible for any reason, funds would be available to restore the current environment and stability to the hillside. A second bond would ensure, should the hillside slide away after completion of the project, any time within the 50 year life projected in the EIS, all property owners whose property values would be affected by said slide, would be adequately compensated. Pages 132-134. "Sewer ". It is understood how encasement of the 12" sewer main in a sealed vent carrier pipe could mitigate the problem of soil erosion going unnoticed from a leak in the line. However, unless the carrier pipe was large enough to actually enter for a person to do maintenance, it is difficult to see how the use of this device would aid in repair of any such leak. Mention is made in the EIS that this method has been successfully used under railways and roadways. However, it seems obvious that a repair and a leak under either of these could be handled by excavation, which would not appear applicable to an 8 unit condominium building constructed on unstable slopes. Page 39. "Traffic and Parking ". It seems that the 1 1/2 vehicles per unit standard is too low. Based on the expected selling price of these units, it would be obvious the owner will be comparatively affluent and would be more likely to own two or more cars per unit and possibly a boat, camper, trailer, etc. We believe the parking requirements as recommended by the Tukwila Police Department in Appendix D should be a minimum requirement. Page 101. "Traffic ". Page 101 has a map showing traffic counts, and we question the reason the traffic counts on the street most critical to this project are all estimates and which to us appear to be low. Page 98 under "Traffic ". We believe the intersection of 160th and 53rd Avenue South is more of a problem than described. Cars coming up 53rd South normally turn west on 160th, which is a normal routing and therefore do not use their turn signals. Cars going straight through onto Slade Way through the intersection also do not use their signals. Driving moving east on 160th and turning north on 53rd are therefore unsure if approaching traffic is turning or going straight through. This problem is going to be increased if this development is allowed and we believe the problem must be mitigated. Page 103. "Traffic and Transportation ". We disagree strongly with the statement concerning left turns off 53rd South onto Klickitat. Though the backups may not often occur due to relatively light traffic, at this time it is virtually impossible to make this turn during evening traffic in hours of heavy shopping. Obviously this problem will be multiplied by additional traffic generated by this proposal. The EIS emphasizes the availability of Metro Transit Service on 53rd Avenue South, but since no sidewalks are planned within the development or on the access roads, it appears that residents within the project would find that walking to the transit pick -up point would have to be done on vehicular traffic, and there are no existing sidewalks for children passage to proposed Crestview Park. Appendix G. A letter from the Washington State Department of Transportation to Engineering Science, Inc. This letter states that the 1" weak drains are obstructed or appear to be pinched off, and that measurements need to be taken to establish a data base for comparison. This EIS does not indicate that this has been done. If this observation is valid, it appears that this problem must be addressed. Work contemplated for this project must not compromise the weak drains or accelerate this 266 type of problem. Thank you. RESPONSIBLE OFFICIAL: The next speaker is Bernie Orati. 5102 S. 163rd P1. Bernie Orati:...I am only going to address one item in here and this is Item G on Page 25, which says that they want to construct a 108 unit cluster and development is going to be 18 with 6 complexes. Each of the 18 buildings will have two -two bedroom units; and 1 bedroom flat and 1 bedroom townhouse. In the Seattle Times article on Sunday, a statement made by Boeing says that the days of tiny condominiums also seem to be over. "I think that the downsize of the point is ridiculous ", Bowman says. Some designers were talking about 300 sq. ft. units. We did some 600 sq. ft. units and they were handsome, but small. But the fewer requests now for these very small stuffy units. So it looks like there would be no sales potential for these apartment, I mean condominiums; and perhaps the owner would have to rent them out on his own in order to come out on a deal. Thank you. RESPONSIBLE OFFICIAL The next speaker is Mr. Heinz Ritter. 5213 South 164th. Heinz Ritter:... I have no comment at this time. RESPONSIBLE OFFICIAL You wish to be called later? Heinz Ritter...May be. RESPONSIBLE OFFICIAL Phil Granger are you wishing to speak? Phil Granger....no. RESPONSIBLE OFFICIAL The next speaker is Robert Christensen. 16241 54th Avenue South. Robert Christensen... My name is Bob Christensen and I live on 54th Avenue South in one of the areas closest to the development that has been proposed. It is pretty obvious to me that after reading the EIS that the developers had no idea of what it is to live in that area. And I think that that has to be addressed. It seems to odd to me that the City can even consider this development. Judging by the reaction of the people that are here tonight, which I am sure is pretty unanimous in the whole area up there. It seems pretty odd to me that this is even being considered. One of the reasons we bought in that area was to get away from the condos and apartments. So, you know, for the City to be bringing them in is kind of stabbing us in the back it seems to me. But besides that, if the developers had lived there, perhaps they would have helped me dig out the nine cars that have been stuck in my front yard when it snows. Because the only way out is up 54th Avenue South. And my neighbor, who is sitting in the back back there will agree that you will not get out on Slade Way when it snows. Neither will you get out at the other entrance down on 53rd. Because they are planning a steep slope up that street. So when we have snow, if this development is around, where are you going to park all those 267 21 22 23 cars? Another thing is schools. I take my daughter to Bow Lake School because the day care she has gone to is up there and the child care is up there. In order to get there I go up 54th and I go up 170th. Well the gentlemen who proposed that most traffic generated from this would go up 160th, I don't believe that. I live there. If you want to get up the hill, you go up 170th, it is easier. And if they are going to make an entrance into this development off of 54th the people are going to use it to get up the hill. The same is true for your shopping. They will go up to the Safeway on Military Road. So the traffic on 54th is not going to increase 25 %, it is going to increase about 300 %. I would like to speak to another issue. I happen to be involved in a development that is on this same street a few years ago. It has since collapsed. But in that development the City stressed to us the necessity of saving as much of the natural flora and fauna that was there when we began. And in this statement they are going to destroy something like 63 percent of the flora that is there? I don't see how they can possibly hope to hold that hill if they are going to destroy all that flora. The City of Tukwila ought to know by the amount of gravel they have picked up in front of my driveway, how much that hill slides. Another factor. When we were going to develop, we were going to put 14 homes on 6 and 1/2 acres. Ok? We were going to have to rebuild 54th Avenue. Make it two lanes wide, and for the stone rockery all the way from my house, which is 16241 all the way up to the corner. Well, if they are going to put 108th units down there below me and add the kind of traffic that we know that is going to be on that street, it seems to me that it is imperative that they rebuilt that street. And one other issue that is particular pet peeves and they both have been mentioned, the intersection of 160th and 53rd, is an accident waiting to happen, and one of these days somebody is going to be dead on that corner. Because, like the gentlemen said, you do not know if you are sitting there stopped on 160th, you don't know which way that car is going to go, and believe me I have come close a lot of times because I have to go straight. And the cars, they start to turn and, you know, and they are dead in the middle. Something needs to be done now, let alone if you put this many more cars in there. And the other thing is the intersection of Klickitat and 53rd. I don't know, but it seems the only solution there would be a traffic light. It is bad enough now to try and turn left. Anytime that Southcenter is open you can forget turning left for 5, 10 15 minutes sometimes. So, you know, if you are going to put this many more cars down there, you have got to put a traffic light. Thank you. RESPONSIBLE OFFICIAL: The next speaker is Mr. Calvin Johnson. 5110 163rd Place. Calvin Johnson...Basically everything has been covered, but I just wanted to make a point here. We moved into our residence in October 1964. Shortly thereafter there was quite a large earthquake, and I don't remember if it was at the end of '64 or the beginning of '65, but at that time ours was the lowest house at that point. The house in which Goe lives in now is not even under here. The ground had not even been excavated yet, but in that earthquake a very large crack developed just at the lower edge below my 268 24 25 property between there and Slade Way which opened up to about a 1' to 1 1/2' and ran into that wooded area to the north of us and clear across his property and over to the about center end of that street and and had about a 1' drop at that point where it slid. So, that to me indicates, and that was prior to any construction up in that there other than, like I say mine . was the lowest house at that point. So that it is indication that the ground being very unstable. And then also, I don't know who is going to be responsible, but it indicated in there that the added consumption of water per day would be around 50 gallons per unit, which works out for 108 units of almost 10,000 gallons of additional water usage. I don't know if the sewers there being 12" would be adequate to handled and they laid the sewer through there a short time ago, or a few years ago, and it was backed by our place, and I know that it wasn't that big a line. Plus I would imagine that there would have to be larger water mains brought into to support that. Thank you. RESPONSIBLE OFFICIAL: The next speaker is Mr. Richard Goe. 5112 South 163rd Place. Richard Goe...I will have to ask you to grab your DEIS, if you will. The location of Site Figure 1. I want to point out part of our problem here on that map. That must be a map prepared by the City, isn't it? That is the one by R.W. Thorpe & Associates is that it? Brad could you step up there and point out to the audience 5112 South 163rd Place where I live? RESPONSIBLE OFFICIAL: You will have to help me. I'll guess Richard Goe....You will need an awful lot of help Brad, because it isn't there. Part of the problem with this EIS is obviously, that what we are dealing with here is a State law that requires to go through this process and so over the years we have developed a "boiler plate" process. I don't know whether people came out and did this, and really spent much time in the neighborhood, but as you can tell from the people who have been up here before me, it is fairly obvious that they do not know the neighborhood and it is no damn wonder that they don't have us on the map. Now there are a number of things that are missing out of this EIS that we, as non- professionals, and I say that in a sense that we are not engineers, not urban planners. We are professional in our own fields and well we didn't plan to get into the kind of professionalism that has been required to deal with this project and the many other proposals that have come up there. But just tonight people have pointed out to you that the EIS is missing accuracy and information about the distances that are shown for the various recreational facilities. Ms Welsh was kind enough to go out and check some of those fantastic differences. The kind of differences and inaccuracies that really shouldn't be there. Missing the nearest school is something that is unconscientable in dealing with the residential neighborhood. The fact that we only have got traffic estimates in areas where the TRANSPO Group has told us that there has been studies taken, they should have at least the information available from the city and it doesn't seem to have that even. The inaccuracies or the inconsistencies of the traffic study by TRANSPO indicated by Ms. West indicating a loss of some cars there. I think they probably got onto South 163rd Place and slid off the hill. Or off the map anyway. Those map layouts of this project really don't indicate the full danger 269 that this proposal represents to the people who live or would live in this project. That large curve to the left top of that map is a blind curve and a very steep angle coming down to 54th. Yet they plan to put two full units in there and have people ingress /egress onto Slade Way on a blind hill curve. Now the people who will be living in those other units further to the east will have a slightly better chance. The hill isn't quite as steep there; however the curve just to the east of them is even more blind and it makes me wonder about the traffic accident potential on that hill without even any consideration of parking on that street. Now if they elect to go out the other exit, they are on a blind hill curve again. And what's more, that particular exit is going to have to be coming up a rather steep hill from the project onto 53rd, which means that they have got an even greater accident potential, particularly in hazardous weather when they try and exit that direction. Now Mrs. Welsh prepared quite a case for what happens when you come out that side. Mr. Christensen who lives on the other end of the project was just as concerned about the traffic coming out that way, and I think they both have a case. Because what we have got, whether these people want to recognize it or not, and its probably because they haven't really looked at the neighborhood and the makeup of it, and that is is that we have a considerable number of attractions up hill from this site. Southcenter shopping center is not the only place that people are going to go from that site, if they live there. And I will say that as a resident who does live there. Clearly there are most grocery stores up hill from the site and down, there are more theatres up hill then down, there are more specialty shops downhill then up, that is because we have Southcenter, and all of its intendent traffic problems. But quite frankly people in a rush want to avoid. The nearest easiest pharmacy to get to is uphill. The easiest cleaner to get to is uphill. It doesn't really matter to me because the school is uphill and everything else is uphill. The fast food places are mostly uphill although some of them are downhill down on Southcenter Parkway, which representation you have up there on the chalkboard. I thought when I came in it was probably Klickitat and 53rd, but I see that it is just another traffic hazard area. I have made the point about that map, but quite frankly, Mr. Collins, a great deal of the maps in here misrepresent in one way or another, either by deletion or by moving the streets, what is really happening up there on the hillside. I don't really understand that from professionals. I want to deal quickly here, if I can with an unavoidable impact. Unavoidable Adverse Impact on page 94. Aside from the fact that the project owners are going to be subject to the conditions of a legal non - conforming use if this project is approved, is pointed out in here. I don't think dealt with very effectively. Because the long term impact has been glossed over so quickly that I really seriously ask you to go back to the project proponent and ask them to deal with that issue instead of just sliding by. And quite frankly that is what I am trying to do here and I think the rest of the people are as well. In listening to the people, it seems to me that the process is to take a look at this and see what is wrong with it, and if we can find it, we point it out, proponent gets a chance to go back and gloss it over and send it back to you. As citizens we are not looking for a whitewash job here. I recognize that this thing has been in process for over two years, just judging from the dates that are in it. But I do find on page 94, the one real accuracy that I can count on in this report, and that is Item #3. That some residents in the vicinity of the site will feel 270 a loss in the quality of life in the neighborhood cohesion. I think they hit that right on, but that is all the more they did with it. And there is a lot more to that statement than just that. It has to do with the things that we have down here to talk to you about before. It has to do really with the things that this project could be and isn't, it has to do with what we as citizens, and as you, the representatives of the citizens in operating the city started to do ten years ago and reached a point of near final conclusion a couple of years ago. This document represents no doubt a heck of a lot of money and a goodly amount of time on the part of somebody, but it really avoids the real issues here. And I don't know how to deal with the "boiler plate" on this thing. But we are relying on you, as our officials in the City who are the professionals, to take a look at this thing and understand what we see it is. I think you have to take the more professional view that you can see the inadequacies of this thing and point them out to us. I would like to ask some other questions that were asked earlier, and that has to do with the liabilities involved with this project. You know the geology of this area really isn't that different from one hillside to the hillside for the most part. I think we are rather fortunate that the hill that we are on right now, happens to have, for some unique reason that I don't understand, the different stability base from the hill that I live on. But, having been out -of -town for a couple of days I haven't been keeping up with the news in this part of the country; but I suspect you have. I was apprised tonight that we have got another hill sliding away. About every two years some place in the local area we got a hill sliding away. And the reason for that is that the geology is pretty much the same. Whether it is on Queen Anne Hill, Beacon Hill, Mercer Island, Tukwila, or even further south. I have talked to professional engineers and asked them how long it takes water from a rain storm to move through that kind of a soil condition. I haven't been able to get an answer. I really hope that you can. Because that is a vital issue on that particular piece of property, and that hillside in general. There are artesian springs in the area. There is one under the property immediately above that. That when they put the street back in, it will be shown on the map. There is considerable spring system in the other portion of this property that is not shown for development that is right across Slade Way. That has a frequency of considerable rain -catch basin along with the spring water overflowing the ditch drainage system along Slade Way. And while we are talking about the vulnerability of Slade Way, I would like a statement in the EIS dealing with the sloughing away of the hillside and the repairs of Slade Way that have been made due to the sloughing of that hillside to the east of Slade Way. That is to say the proposed property's project site. I would like to know under what conditions of seismology we could expect that hillside to stay stable or be unstable enough to move. Whether it be surficial, or deep- seated movement. I think those are both important issues to this site. There are two great water levels here on that hillside and I suspect properly engineered in dealing with a large enough water retention system, which I don't think is dealt with properly in here, for that hillside. I think it might work on some other hillsides, but I don't think there. The water and the deeper aquifers were found in the drilling above and below the slicken slides indicating slide movement and I understand from our geological technical person, that those slicken slides you cannot tell without considerable expense of analysis whether 271 they are 10,000 years old or ten minutes old. And I don't see that dealt with in the geologists report. It shows in the borings that the slicken slides are there, we all know it is a slide hill, and that there has been slides on it within the last twenty years. We are not really dealing with that issue. I think the the geo -tech report makes some recommendations. I think the noise abatement people made some recommendations; the traffic people have made some recommendations, but the draft EIS is still is filled with coulds, cans, wills, maybes, that are not responsive, in my opinion, to the definite fact that things will be done to mitigate the adverse impacts that are shown throughout the report and that are not dealt with. I personally feel that this thing is filled with lack of information and inaccuracies to the extent that if you had to deal with this report tonight, I would charge you with the responsibility of turning it down. Now we have come down here tonight and the only process we have available, and that is to show the proponent where he has screwed up so he can go back and fix it for you. And I will charge you with the responsibility on our behalf of making sure that he does the job right the next time or cancelling the project's future. Thank you. RESPONSIBLE OFFICIAL: The next speaker is Eleanor McLester. 5118 South 164th. Eleanor McLester:...One of the first things that I would like to say tonight is that I am much in agreement with the fact that the noise down in that area from the freeway .could very well be unacceptable, because I don't know about my neighbors out here, but this year for the first time I have noticed with the trees and the shrubs bear, I am hearing the freeway noise worse than I have ever heard it and I live on one of those streets that's unidentified just above the hill there as well. So that noise has crept into our homes with no development and no disruption down there in our present state. But one of the things I'd also like you to take into consideration, would you please run your pencil down along Slade Way there to the bottom of the hill by the site and then turn where it would go back up, to go up to 53rd and then on up the hill to 170th. Let's come the other direction please where we will turn here and then go on up and you will end up going up the hill on 53rd there and up 170th to the shopping centers, schools, recreation, the airport, any of those kind of areas. Since I have been living on the hill, we have had 54th closed because of slide activity more than one time, since we have been up on that hill. And I think that we have very good history here in the City for the amount of money that it has taken us to maintain that access for single family residents on that hill. Furthermore, I charge the planning commission to ask for some additional input to the EIS by talking to both the street and sewer departments and Chief Crowley at the Tukwila Fire Department, because we cannot get our large fire rig up Slade and around that corner and up 54th. That has been one of the things that we have talked about. Our big unit has to be timed to be going back to the opposite direction up 160th and down around to the Bosch residence, the people over in that area because our big units are not safe going down Slade Way, turning down that corner and crawling back up that hill. So I think that we need to have the reports of the fire department for emergency vehicles. And let's face it, if we are going to put that kind of density in that area, we are going to have emergency vehicles whether they be ambulance for wrecks, and believe me, that is a high probability with that density in that area, whether we 272 are going to have fire department vehicles, etc., we need to take a look at what construction of this magnitude in that adverse site, the impact that it is going to have on our emergency services and our city's departments of police, fire, and roads. So I ask that you do that and give us some answer back from our departments if you would please on how they see that development in that area impacting their ability to maintain a safe area for the residents. Thank you. RESPONSIBLE OFFICIAL: The next speaker is Mr. John Swartzman. Audience member,: Not here tonight. RESPONSIBLE OFFICIAL: The next speaker is Mr. Heinz Ritter. Heinz Ritter: No, please. RESPONSIBLE OFFICIAL: Is there anyone else who wishes to sign up and speak? Tom Johanson...I live right at the bottom of Slade Way and 54th South and I just wanted to make one observation, a minor one on your Policy 6 on Page 39, where it talks about the encouragement of the development of pedestrian right -of -ways, overpasses, well -light trails which can provide safe passage for residential areas to commercial and service and recreational areas. The comment is, is the site is not within walking distance of commercial use. I believe there is a walkway just to the north of that site with some nice stairs that go down and over the years it has been my experience or knowledge to know that there is some pedestrian traffic that does come down 54th and cuts through the lower end of the property and it is not all that far from Southcenter and with this many people in these condominiums, the improvements of all those walkways in that area I think would benefit the project. I think you would have a lot of people especially if we talk about as many single bedroom units, that we are going to have the need for potential joggers, walkers or other active people. RESPONSIBLE OFFICIAL: Are there any other speakers that wish to come forward and talk about the DEIS? Mr. Robertson? Dennis Robertson... I was thinking through what you had said earlier about the process. I guess it comes back to what is the purpose of the environmental impact. Is it true that if they don't mitigate the impacts to, I guess in this case to start with, according to your desires or your view, than they don't get to build the project? Once everybody agrees on the statement is correct, that means they either modified their building plans, they changed what they are going to do on the street, they said they are going to have less people so we don't have more traffic. In any case, once that is agreed to be correct and the statements are correct, if something doesn't change, can the City stop the building process? RESPONSIBLE OFFICIAL: Let me try and answer your question. The purpose of the EIS is to identify impacts that might possibly occur, if there is a reasonable probability 273 that such impacts would occur, and particularly paying attention to those impacts, adverse and potentially significant. From the description or an explanation of the indication of those impacts is the purpose of the proposal to try and identify how they would mitigate those impacts. Those impacts which are not mitigated then become adverse impacts which are unmitigated, and based on the review of the Responsible Officials in making a decision, in this case the Building Official, they would determine whether or not those unmitigated adverse impacts would cause them to either 1) deny the project; 2) to make conditions based on those impacts and would mitigate them or; 3) accept the unmitigated adverse impacts as consequences that cannot be avoided. Those are the decisions that would be made by the person that is actually doing the issuance of the city action. The impact statement first and foremost identifies the impacts, it identifies where the proponents mitigation to those impacts is, and then what impacts are not mitigated. Which unavoidable adverse impacts remain and once those are identified, as well as alternatives and the other required information in the DEIS, then the City official that is responsible for making the decision, will be fact on that information. Mr. Dennis Robertson...Is there any city or state codes that direct how severe a negative unmitigated impact has to be in order to turn it down. Are there any guidelines or codes, laws? RESPONSIBLE OFFICIAL: The answer is no. We have to use our own discretion definitely, and that has to be viewed ultimately by a court of law. So whether or not we are reasonable in that judgement. Robertson. Thank you. Herb Phalan...I was one of your early speakers and I have been listening to all the others and all of them have some very incredible objections to this impact statement as it currently exists. I would like to go back and ask that same question again. How are we going to get feedback as to how you have addressed all of these objections and if it's going to be part of the Final Draft, where there be in that Final Draft, a point -by -point list of the objections and how they were handled? RESPONSIBLE OFFICIAL: Yes. We will fill out a point -by -point response to comments that have been made and how we are responding to the comments either by changing the information or by acknowledging that, yes that it is an impact and it is adverse and unavoidable and that information will be published in the document, which we call the Final Environmental Impact Statement. It will then be available to the public and ..e tributed to people on the distribution list. Darlene West...I just have a couple of questions. If you ok the EIS, based of course on the information that they have put in it, and it contains enough inaccuracies such as were very obviously stated tonight. These are professionals. It is their job to do this EIS properly, accurately and they have not done so. If I were asking for building permit and I misrepresented what I was going to build in that fashion, you would say I was cheating and dishonest. Now if, per chance that these inaccuracies get past and it's ok'd and they get a building permit based on that o.k. and 274 these inaccuracies come to light, can the building permit be rejected? What happens then? What if they have broken ground and they done something and then the City finds, or it is brought to their attention that it was allowed to begin the project because of these inaccuracies by these marvelous professionals? RESPONSIBLE OFFICIAL: Generally speaking, what happens is the professionals that are reviewing the environmental information will try to make a reasonable judgement as to how adequate the statements are, how well the responses, answers to questions that were raised in the coal_ nts, and how generally accurate the document is. If, after that udgement and there has been no stamp that this is 100% perfect that was put on this, if reasonable people differ as to how accurate that information is, the process for appealing is refers to an inadequacy that there would be certain information in the document and omission in the document which do not make the document in-a- ...+Liriadequate statement of environmental impacts. The proper procedure if you have questions of the City professionals, or the consulting professionals that have put information into the document, and you are not satisfied that the Responsible Official has adequately come to grips with those statements, than the correct procedure is to appeal the adequacy of that EIS first to the City Council, and if unsatisfied with the City Council, then presumably to the S4a4e Court. Every effort is made to try to make the EIS an adequate EIS. It's is not intended to be a document that has no imperfections in it. It is intended to reach a reasonable standard of inadequacy and that is the rule by which the state court would ultimately decide whether it was inadequate or adequate statement. If once you are through and someone can find that there is a distance to a playfield that is inaccurately stated, and that will be the only problem; it is not likely that the document would be ruled in adequate because of that one inaccuracy. If there are many inaccuracies or one's that are significant, documents have been ruled to be inadequate and then the process is referred back to a. start point and inadequate environmental impact statement has to be prepared. So, every attempt is made to provide accurate statements. One of the reasons for the Hearing tonight and for comments is to try to find out if there are any inaccuracies that people with more specialized knowledge might know; and we will try to respond to those comments and include incorporation on the changes in the documents to be reflected in a more accurate statement. Eleanor McLester...We have had numerous studies on that hill, both down where the new park is going to be developed and down in the Slade Way area there on the hydraulics on that hillside. I would venture to guess that if we have had one, we have had 1/2 a dozen different developments and statements come in on the hydraulics, the possibilities of a slide, the flow of water and those kind of things coming in. I cannot remember any two being within a quantum leap of the other one. They have gone from conservative to outrageous. How can the City-.do they have the authority to get independent collaborative testimony and expertise in on something of that magnitude in that area? We're talking about -- do we have an adequate or inadequate environmental impact statement, and I am far more interested in an accurate or inaccurate. To me there is a whole world of difference between adequate and inadequate and accurate and inaccurate. When we take a look at engineering firms who have put together something as expensive as 275 this document, and we find even errors in things that should have been simple to measure, when we get into that hydraulics area, perhaps we need an independent authority if that is possible, especially on something that important. RESPONSIBLE OFFICIAL: I guess I would address that as a procedural question. The answer procedurally, I believe, if there is an area where we do not feel we can adequately answer the question, our experts are not expert hydrologists, or soils engineers, we may get an analysis of that. We do not charge the applicant. The applicant is bearing the expense for the EIS. We are reviewing that and presumably we will bear the cost of any individual's analysis of any consultant information provided by the applicant. But the answer procedurally is that we do an in -house review, the information where we don't have the expertise we may in fact get an independent second review. Bernie Oronati...On page 57, which shows a contour map on it, which has soil analysis on it and there are statements in the back of the book that is made back here, and I am going to take one of them now. On page 60, second paragraph, it says that if the slope is 33% it should be supported by retaining walls. I have a question. Does the City Code, on this project, will it force them to put in retaining walls for any of those slopes that are 33% on that, plus the fact that is that if you take for instance, the upper left hand corner there, each one of those contours is 5 feet apart on this map. So this shows that you have got about 25 feet on this and that would be well within the 20% range of that. I can't see where any of that white area is less than 20 %. So I don't know how much the slope is say 6% on it, which is roughly what they are showing on this street up here. It is roughly a 6% grade. RESPONSIBLE OFFICIAL: That is not a procedural question, but I won't answer it tonight, but we will answer it in the Final EIS. Bernie Oronati...Ok. But I am questioning the grades on this map. Thank you. Barbara Welch...I am at the end of the street that is missing on the map. I am right up above the project overlooking the hill and I cannot to afford to spend $90 an hour for a legal question. Maybe you can answer it for me. If they proceed with this project, and part of my backyard falls down, which it will, what grounds do I have to fight it and I can't afford to move, how do I get my money out of my house? If I go to a lawyer with this question, it is going to take me 2 -3 hours to describe the problem. And I just can't afford it, and I think we all should know some of the legal rights that we have in that area. How are we going to get this answered? Are any people going to write us a letter with these, or how are we going to find out these answers? I am very concerned. Because I will lose my backyard and I think a couple of others will also. RESPONSIBLE OFFICIAL: I am not aware, so I can't answer your question. But we would be happy to have you call the City attorney about a question like that. 276 Barbara Welch... Is that going to cost me money? With my questions and my concerns about what legal rights we have? RESPONSIBLE OFFICIAL: No, if you write a letter to me and address I will make sure the City attorney gets an answer to you. Barbara Welch... And they will write back to me so I have some legal rounds? RESPONSIBLE OFFICIAL: They might write back to me, but I'll try get an answer through the City attorney in question. Essentially property owners have properties and if your property is damaged by an action of another person or agency, then you would have some rights of claiming damages. As I say, I am not a lawyer so you are asking the wrong person. John Schwarzmann...16251 52nd South. I have been sitting back here listening to this and if they do built this development, and if after a year or whatever the people realize that they can't possibly live in this development, are the citizens of Tukwila going to have to buy this out like the Port of Seattle is buying out all the property around the airport? Again, I don't know if that is an environmental question. But I wonder if we can answer that? RESPONSIBLE OFFICIAL: That is not a procedural question. John Schwarzmann...I understand that. RESPONSIBLE OFFICIAL: We will try to answer it in the context of the Final EIS. Dennis Robertson...How long can this process go on? Let's assume that they correct or change the Draft EIS. Then there is another review of it, more input. And eventually, let's say it's turned down. Let's say that you say that it is not that the City says that they don't mitigate the damages or the impacts. The question is how long does this go on for this particular piece of property. Since it came in, under that small window with a single building permit and it is in a non - conforming area does this end if it's turned down if they are required to put together a different building plan. Do they get a chance again? Or how long does this one go on? RESPONSIBLE OFFICIAL: Let me try to address the question. Procedurally, the EIS, if the decision is made to go to a Final EIS following review of the comments and the judgement on the adequacy of the Draft EIS, once the Final EIS is published, the environmental procedure would then have seven days later, unless there is an appeal, and it goes through the appeal process. The appeal process especially goes into court, could - a considerable problem. Dennis Robertson...Are the modification of the particular building permit, say a change in the number of units or a major change in the layout be considered a new building application? 277 RESPONSIBLE OFFICIAL: Under some circumstances, yes, and in other circumstances, no. Dennis Robertson...My concerns are not only on behalf of the citizens that live on the hillside, but on behalf of the City as well. We have had testimony before the City Council and I believe for the benefit of the planning staff, from John Barnes, one of the local residents on the hillside who lives basically off of 51st and 158th extension, I don't really know his address there. He has given us testimony to the health problems that he has developed over the years due to living in the proximity of the freeway. I have nothing to substantiate that, that's was John's statement about his health and whats happened there. It seems to me that the City has considerable liability to approve any project or even consider approving a project that is going to put the number of people that this project assumes into a health risk that is identified quickly and kind of forgotten here in terms of asthma and heart disease or other problems. I am aware also that there have been studies relative to good health or poor health and noise levels. I haven't been able to access any in the process up to this night. And I would ask that you do to determine the health risk that is being proposed for the people who would live in this project. That hasn't even been mentioned. The only mention of noise is the potential mitigation of a few dBA to get it down to a level that would not impede speech and hearing of a normal conversation. And without being able to talk to a person who is involved in noise studies, and I expect you have :them available to discuss this with, it strikes me that even getting down to the minimum of 55 that was mentioned in this Draft, that would just barely getting to the top end as a maximum as opposed to a minimum, where noise levels ought to be in residential areas. I want to deal with another thing that was brought up in this report and that is the social impacts by this project would change considerably depending on whether these are condominiums or apartments. And quite frankly they are apartments. Make no mistake about that. The fact that they are "owned apartments" and that term has been euphaminized as "condominium or townhouse" any number of euphemisms that get it away from the actual term "apartment" does not mitigate the reality that it is an apartment and that the potential for being a rental unit is real and very high. I will have a procedural question out of this and that is, "can you or any one of the City bodies that has to deal with this Draft EIS and the finalization of it, in the process require a covenant that if this project does proceed, that there can be no absentee owners in renting the unit out. Now we have, as citizens presented to you, at times in the past for various projects that we have had to deal with, statistical information regarding crime rates, traffic problems, etc., that become attendent to apartment zoned areas as opposed to single family residents as unattached. We have talked to you before in terms of the valuation of property adjacent to this kind of site as proposed here. Dr. Allenbach suggested to me one time that if he was allowed to put in his project there, it.would increase the value of my property. What it meant to him the potential value of the land would go up because it would then be an apartment area and the land would be more valuable because the house could be taken down and an apartment could be built. I don't consider that a reasonable alternative in there. Although that is historically what has happened in areas where departments have gone 278 in. The value of the residence diminishes rapidly; the value of the land may increase but it does not increase to the total value of the land and the residence that is on it in an area that does not have apartments in it. It would seem to me without legal advice yet, that in allowing this project to go in you are, in fact, diminishing my property rights while you are enhancing those of the project proponent. And I don't know if that is economic or environmental. It has to do with greens, so I figured it is environmental right now. I am concerned about what might happen there and quite frankly again, 1) as a citizen and; 2) on behalf of my City. Where you could wind up with that sort of project. It used to be, Brad, that ?3% of the dwelling units in this City were multi's. This Draft reckons that it would go up to 76% and I am sure that was without any consideration of the project that is currently going on in the west slope of this hill, which name I don't even know. Can you advise us how many units are going in over here now? RESPONSIBLE OFFICIAL: Again, it would have to be beyond the scope of this hearing. Dennis Robertson...I don't think it is not pertinent, I think it is pertinent in terms of... RESPONSIBLE OFFICIAL: It would4. be a procedural question in this Hearing. uaT Dennis Robertson...The impact here we are talking about is two fold. We have already had identified for us that we have got an overload to the sewage processing plant based on information that I presume was developed prior to that project going in, and even taking into consideration. Be- cause the 73% that is identified in this Draft EIS, is the same 73% that we were talking about 2 or 3 years ago. Now we got again another major project going in here that I suspect is probably at least equal to the size of the proposed project that we are talking about here. It is going to be finished because its already started and nearly completed before this one ever gets off the ground. Time has caught up with this Draft. And I think those kind of things, and I only point out one, need to be watched and addressed and updated before they come back with the Final EIS. I think it is more important than ever in light of that new development on this hill, and the overload to the service system and the sewage treatment plant what that will do in terms what this one could do. What are the relative sizes? When is in fact the METRO, the plan going to be implemented for improvement, if at all? Because this Draft left me with the distinct impression that there was a rather large question about that ever being implemented. I think we would be really foolish to proceed with a project like this that does not have absolutely 100% clear go -ahead from every angle and it only becomes slightly apparent to us as non -pro's in the . planning field, that the future holds an awful lot of things that must be considered before you can even allow this to go any further than it has tonight. And we don't know what most of those are. We can identify certain ones that relate to our area. And Mrs. McLester has hit on a very high impact zone, and that's with the City services. I don't expect to have to have that fire truck up on the hill with any frequency. But we are going to have garbage trucks up there, we have them up there now, and they are there at least once a week. Those are pretty good sized units. I know 279 what they can do to children, because I know what one did to one of mine. I'd hate to see any other child hospitalized because of a big vehicle like that being out of control. I have concerned myself without any further improvements to Slade Way or the entire road system on that hillside. What that kind of vehicle can do to Slade Way in the early spring when the hill is wet, even with surficial water when Slade Way is still moving. I would like to have a very definite statement from the Washington State Department of Transportation giving the absolute guarantee that its project proponent requires and alludes to, and in fact, recommends that the State has a moral responsibility to that property owner somehow. I quite frankly don't believe it, and I didn't see anything in the comments from the Washington State Department of Transportation that anywhere indicated that they felt that way. But since this project requires so much from guarantee of the maintenance of that system from DOT, then I would definitely like to see that in writing from the DOT before any process of continuation is made. I tried to go back and cover all of my notes here and I think I've covered all the things I want to at this time. I thank you for allowing this opportunity. I know it wasn't absolutely necessary, but we appreciate it, and I hope that the things that we pointed out are merely the beginning for you of the past of reviewing this and having the proponent knuckle down on this thing and get serious about it. I don't consider that the EIS process is something about to be glossed over, I hit that pretty hard before, and I am really serious about because there are two sides of this that we have to worry about. That's us, the citizens up there, and the other one is the City and the impact of where we are going to wind up as a City if something goes wrong with this, and that is why we rely so heavily on you to get the information from the professionals for us to make sure that this is accurate, and not allow to get away with anything here, however unintentional. Because I think these people are professionals, and I don't expect that they want to go out and do anything that is going to harm people, but I think they are working towards a different motivation, and that is the "profit motivation" as opposed to the motivation of maintaining a good viable residential neighborhood where we live. Thank you. Darlene West....I think this question has been asked, but I am not sure that I really understood any answer. When this goes to Final EIS, and you said there was 7 days for it be appealed, you said we were going to get copies of it, are we going to get copies of it far enough ahead so that within the 7 days we can question it, will there be another Hearing such as this during that 7 days or what? RESPONSIBLE OFFICIAL: Once we publish the Draft EIS, it will be mailed out that date that that is published and believe it is being mailed out 1st Class mail. So I would expect you would be receiving it within several days at the most. There is no scheduled Public Hearing. The Final EIS is a longer period of time in terms of appealing the adequacy of the EIS. It used to be 30 days, with the new regulations - I am not sure now. But I believe you have a longer period of time to appeal the adequacy, it's just 7 days before the City could take any subsequent action. The City will not be issuing a building permit that quickly because we have to also go through the Board of Architectural Review on this project. So, you do have a longer period of time for the appeal get—the adequacy. And I am sorry that I can't give you that, if you can bear with me for a minute -- 280 Darlene West...If you ok this, and it goes on, and a building permit is going to be issued or if it comes up to whoever before that building permit is issued, will we be notified of any hearings or meetings about that or public input on that? Or are we just going to get a copy of it and "tough luck lady it went through anyway ?" RESPONSIBLE OFFICIAL: There is not a commfnl-period on the Final EIS. Darlene West...Yes, but then if you decide ' ou are going to decide whether or not you are going to issue a permit bas: d on that, is that all done in- house here? There is no more public involvement in that? RESPONSIBLE OFFICIAL: There is not a Public Hearing for the issuance of the Building Permit. The Board of Architectural Review is a public process, and it is open to the public and... Darlene West... That would be after the EIS was approved and before the permit was issued? RESPONSIBLE OFFICIAL: That is correct. arlene West...And that will be publicized and we will be notified? RESPONSIBLE OFFICIAL: Generally s eaking we notify property owners within 300 feet of the property the Board of Architectural Review. So, it would not necessarily mean that everyone on the EIS list would be notified. So, the only thing I could advise you is that the Board of Architectural Review meets the 2nd and 4th Thursdays of every month and you could certainly contact the Planning Department to find out when this particular project will be on the agenda. It would not be on the agenda, until at least 7 days after the Final EIS. I believe that the ordinances and appeals are filed within 10 calendar days of the date of the decision. Darlene West...Date of the decision? That is the date that it is going to be mailed to us? RESPONSIBLE OFFICIAL: 4-164 400. Correct. Let me read you the sections. Any person may appeal the 6441P-dills Kdete4mi,pati Ja equacy of the Final EIS, and the conditions for a denials madey y nidfY= . %ed official pursuant to the procedures set forth in this Section, that will be the issuance of a permit. No other SEPA appeal shall be aticuAti, All appeals filed pursuant this section must be filed to t City Clerk within 10 calendar days of the date of the decision of appeal lime. So, if you are appealing the adequacy of the EIS you would have to file on behalf of the City Clerk in ten calendar days of the issuance of the Final EIS. Rick, do you have any other information on this? Rick Beeler...The new guidelines have been something that is new pursuant 281 per the Red Book, and that is that also you have this appeal to do this mentioned, but there is also that new guidelines tie the appeal to the governmental action and in which case we have two .that are involved here. One of which is the Board of Architectural Review, the discretionary approval and; 2) we have a building permit, which is another approval. So, it appears in reading the appeal on the adequacy of the Final EIS, could be tied to the Board of Architectural Review action and the appeal would occur within ten calendar days of the Board of Architectural Review action. It appears that that would be the longest period for the appeal to be launched. We would issue an official notice. RESPONSIBLE OFFICIAL: On this particular procedural question, what I will put that into the Final EIS so that question would be clearly understood, so that if there is a question when we appeal the inadequacy of the EIS can be filed, that should be clarified for you in the Final EIS. Joel HaE gard....On behalf of the applicant. I have taken rather exhaustive notes here tonight listening to perhaps not only what has been said, but also hasn't been said. And I think that I may disagree with the comments or conclusions in any one detail here or there, but I think it is also very obvious to me that the people who have stood before have expressed their concerns so far tonight are concerned. And it was very obvious that one of the concerns was based upon really understanding the State environmental policy act process and their involvement in the decision making to the extent that the law permits it. I certainly share with them the desire that the EIS is adequate, because it certainly it does my client no good whatsoever to have an inach'quate EIS and have to go back through the process or to have it challe: ged. And the job is to be done now, but I do recognize Brad that the EIS is not ours to write, it is the City's document, and the City is the one that directs the methodology and the contents and the response, and I look forward to working with the City to the extent that you desire that in assuring that an appropriate document is prepared in final form. I have also listened to the concerns with respect to some of the turning movements, the traffic, the width of shoulders, the distance to recreational areas, slope stability, size of pipe, building over a sewer pipe with a sleeve on it, and a lot of other concerns like this and frankly I intend to review these with my clients and into the context of the entire EIS, and the studies and the professional judgement, and to the extent that it is appropriate or advisable from the applicant's standpoint to respond specifically to these suggestions, we will try our utmost to do that within the next few days for the deadline, if not, then perhaps by way of response to the comments we can supply additional information to you for your use in the final document. Thank you. RESPONSIBLE OFFICIAL: Is there anyone else that wishes to speak? J,ouis Haves. (16634 53rd Avenue South). On one of the streets that should be very interested in this project, I contacted 15 people on our street, and not one of them knew about this meeting, and we would like to know where we went wrong, because we have been interested in it and worked on this project. I want to know how these people that really should be 282 notified or know about this can get on the list and receive information? RESPONSIBLE OFFICIAL: The procedures that will be followed for notifying the public, we publish notices in the newspapers, we have taken names from previous appearances at involved Hearings on this particular site or project and those people that are within certain distance of the site and the agencies that have jurisdiction, and that was how we generated the distribution list. Anyone that feels that they need to be contacted, can certainly contact the Planning Department, City of Tukwila, and we will try to provide notice and contact those people about information regarding this particular EIS. In that regard, please sign your name and address on the list ( and also the previous speaker). I hope that answers your procedural question. Are there any other people who wish to speak tonight? If not, we will close the Hearing, and thank you very much for your comments this evening. 283 Response to comments made Herb Phalan 1. Comments acknowledged. HEARING TRANSCRIPT y Response to comments made by Ethylmae Cole 2. GeoEngineers, Inc. has issued a revised Geotechnical and Hydrological report (Appendix A) and the text of the FEIS has been updated to better identify existing conditions and include general requirements for (i) monitoring of soil and groundwater conditions; (ii) maintenance of existing and proposed facilities; and (iii) posting of bonds by the developer to provide the funds for necessary mitigating measures. Refer to revised Earth Resources discussion in the FEIS. Response to comments made by Darlene West 3. The proposed development and the EIS have been revised to reflect that por- tions of the existing 12 -inch cast iron main will be relocated so that it will not be underneath proposed building locations, as shown on the site utility plan on Figure 16. The realignment traverses the hillside higher upslope, resulting in a maximum excavation depth of approximately 20 feet. The maximum depth of excavation for the existing sewer line in this area was on the order of 15 feet. In the opinion of GeoEngineers, Inc., the proposed realignment of the sewer is feasible provided that the excavation is pro- perly designed and constructed (reference the October 16, 1985, letter from GeoEngineers, Inc., presented in appendix A of the EIS). 4. Market value reflects a number of factors, including the location, costs of developing a site, local amenities and adjoining properties. As noted on page 23 of the revised EIS, the costs of site improvements for single - family residences could result in house value increases that could discourage prospective buyers. 5. Please refer to revised cross - section drawings of the project (Figures 18, 19) for view impacts on undeveloped properties along Slade Way. 6. The R -1 area was not included in computing the development potential allowed in formerly multi - family zoned areas. The project will be brought into con- formance with all setback requirements of the City's Zoning Code. The R -1 property is incorporated into the project open space. No future development on this site is expected. Changes to the project could occur through sub- sequent environmental review only to the extend that no significant adverse 285 environmental impacts occur that were not addressed in this EIS. The only changes that would be anticipated are those imposed as conditions of permit approval to reduce or eliminate significant impacts identified in this EIS. 7. As indicated on page 22 of Appendix E, a total of 182 parking spaces are proposed by the Developer. The Urban Land Institute indicates that suburban apartments typically exhibit maximum parking demand between 10:00 p.m. and 6:00 a.m., the time when most residents are sleeping. At all other times during the day, the parking demand generally is less. This indicates that the visitor demand does not exceed the amount of resident parking, which is unused at any time during the day. Thus, it is not anticipated that demands in excess of the parking supply would occur. The NO PARKING areas due to fire lane designation will not decrease the proposed parking supply. As indicated on page 25 of Appendix E (Draft EIS), it is suggested that recreational vehicle and trailer parking be accommodated off -site and enforced through the development's covenants and restrictions. 8. The 90 vehicles per hour identified for the evening peak hour reflect the total site - generated traffic which would access all streets in the area, not any single street. As indicated on Figure 6 on page 17 of Appendix E, 65 vehicles per hour (vph) of the 90 total peak hour trips generated would orient northward along 53rd Avenue S. About 25 vph would orient westward on South 160th Street. As indicated on page 18 of Appendix E, it is acknowledged that other roads in the area may be utilized to a lesser extent than these two primary access corridors; however, to reflect worst case impacts on these two main access routes, all traffic was assigned to these roads for analysis purposes. The impact of this traffic entering the 53rd Avenue South /Klickitat Drive intersection is identified on page 20 and 21 of Appendix E. As indicated, no substantial decrease in average hourly level of service for the evening peak hour would occur as a result of project - generated traffic -- the worst movement (northbound left turn from 53rd to Klickitat) would function at LOS D with or without the proposed project. Sporadic delays to left -turn traffic from Klickitat Drive to 53rd Avenue South would increase slightly as a result of the 25 additional hourly trips generated by the proposed project. The proposed mitigation is discussed in Response #6 to the King County Planning Department as well as the FEIS and Appendix E. On a daily basis, while the development will generate a total of 900 trips per day, about 530 trips would be expected to orient to the north on 53rd Avenue South. As indicated on page 18 of Appendix E this reflects a 23 percent increase in traffic on that roadway link. While this increase will be noticeable, the total forecasted traffic with or without the project is well within the traffic carrying capability of two -lane road- ways. 9. See response to #8 above. South of South 160th Street and 53rd Avenue South the impact can be derived by adding the daily project traffic volumes shown on Figure 6 of Appendix E to the 200 vpd shown on Slade Way /54th Avenue South on Figure 7 of Appendix E. This indicates that project traffic would increase 1987 traffic on this roadway from 200 vpd to 380 vpd, a 90 percent increase. While this increase will be noticeable, since non - project volumes are low, the 380 vpd forecasted with the project can be accommodated by the road section as it exists. With the project, Slade Way will still be a "low volume" road. 286 10. As indicated on page 6, Figure 3 of Appendix E, Slade Way is estimated to carry about 200 vehicles per day currently. As indicated on Figure 6, page 17, about 110 project - generated vehicles per day would be expected on Slade Way between the two proposed access driveways, reflecting a 55 percent increase in traffic on this link. East and south of the main project dri- veway on Slade Way /54th Avenue South, daily traffic volumes are forecasted to increase about 15 percent from 200 vpd to 230 vpd as a result of project - generated traffic. While these increases on a percentage basis appear significant, the low baseline traffic volumes, both existing and forecasted non - project, are the primary reasons for the appearance of substantial increase. The traffic volumes forecasted for these roadway links will be reviewed by Tukwila Public Works for the building permit. 11. Page 20 of Appendix E identified the impact to traffic left turning from 53rd Avenue to Klickitat. Without the project in 1987, about 15 vehicles would turn left during the evening peak hour; with the project, 20 would make this movement -- an increase of 33 percent or 5 vph. Response to comments made by Dennis Robertson 12. Comments acknowledged. See revised Land Use section in the FEIS and comment on Residence Objective #1 in the Plans and Policies section of the FEIS. 13. GeoEngineers, Inc. has issued a revised Geotechnical and Hydrogeological report (Appendix A) and the text of the FEIS has been updated to better identify existing conditions and include general requirements for (i) moni- toring of soil and groundwater conditions; (ii) maintenance of existing and proposed facilities; and (iii) posting of bonds by the developer to provide the funds for necessary mitigating measures. Refer to revised Earth Resources discussion in the FEIS. The EIS has been updated to better identify storm water discharges, flow paths, and the off -site properties that are expected to receive these discharges. The revised discussion of existing site drainage conditions, impacts, and proposed mitigative measures are presented in the section under "Water" entitled "Surface Water Movement, Quantity, Quality, Runoff /Absorption of the revised EIS. A detailed risk assessment that could accurately quantify the probability of slope movements under various site conditions is generally not required for site development and may not realistically be able to be performed for this project. However, the factor of safety for slope stability can be assumed to imply a general level of risk (low, moderate, high) for slope movements. The text of the EIS has been revised to include such statements as appropriate. It is the opinion of the geotechnical consultants that the deep- seated sta- bility of the project site would be jeopardized only if the WSDOT drains were to fail. The updated discussions and mitigating measures presented in the EIS are believed to adequately address these issues. See revised 287 Geotechnical /Hydrology Report, Earth Resources, and Water Resources sections of the FEIS. 14. The EIS has been upgraded to include the mitigating measures that the City of Tukwila, its officers employees, and agents be indemnified from all claims, damages, losses, or liabilities arising directly or indirectly from any earth movement on the site. The EIS also has been revised to include general statements regarding (i) bonds required of the developer and project owners, and (ii) mitigating measures for covenants on the property deeds. Response to comments made by Barb Welsh 15. See Hearing Transcript Response #7 to Darlene West. It was anticipated that some parking for Buildings 1 and 2 will utilize the parking immediately to the northeast on the main circulation road nearest to the Buildings. As indicated in Mitigating Measures, page 25 of Appendix E, no on -site spaces should be reserved for any particular unit. Since Slade Way in the vicinity of the driveways for Buildings 1 and 2 has a grade of between 15 and 20 per- cent, as well as little shoulder area, it is expected that the on -site spa- ces located to the northeast will be considered more desirable than potentially using Slade Way as on- street parking. The reference to 3.07 vehicles per household for single family homes in Ms. Welsh's neighborhood is not a transferable rate, and thus not appropriate to apply to apartments of the size proposed here. 16. According to the project architect, one out of every 20 units must be supplied as "handicapped." "Handicapped" is meant to apply to wheelchair - bound, the blind, deaf persons, etc. (i.e., a wide range of handicaps), and not only wheelchair - oriented. The State has found that a parking require- ment of one handicapped space per 50 parking spaces is an acceptable limit, and is thus also a requirement for this development. The handicapped units are on the mid -level of the tri -level six- plexes, and thus require no stair- way access for handicapped persons. A ramp could be installed (according to the project architect) to the play area to accommodate handicapped access if so desired. The project sponsors position on this change is undetermined. 17. The FEIS has been corrected to indicate that elementary school age children residing in the project would attend McMicken Elementary. According to the Highline School District, the school has a capacity of 425 students and a current enrollment of 356 students. Thus, the school can easily accommodate children from this project. 18. See Response #3 to Carl Jensen above. It is also acknowledged that icy and snowy conditions may cause alternate walking routes to occur. 19. It is acknowledged that South 160th Street between 51st and 53rd Avenues represents roadway cross section and shoulder condition that is narrower than the "typical" section generally identified in the DEIS which more accurately reflects South 160th Street west of 51st Avenue. Discussion 288 relative to potential mitigation of this narrow shoulder condition is discussed in Response #3 to Carl Jensen above. Discussion relative to the adequacy and potential use of Slade Way for on- street parking is discussed in Hearing Transcript Response #15 above. It is unclear where the commen- tator has arrived at traffic rates of 3.67 vehicles per minute at the entrance to the complex on South 160th and 3.5 vehicles on South 160th bet- ween 52st and 53rd Avenues South. It is also unclear what traffic scenario (i.e., Future, with projects, or project only, or existing traffic) is implied. However, vehicles per minute is not an appropriate rate for ana- lyzing traffic; most accepted methodologies are based on an analysis of hourly volumes. This represents about one vehicle 2.5 minutes attributable to this project. This also reflects traffic conditions which would likely occur between 4:30 and 5:30 in the evening. This is well after most children would be walking to their home from the school bus. The rate of project traffic occurring earlier in the afternoon, when school children would likely be using this section of shoulder, would be less. Discussion relative to the shoulder widening on this section of 160th Street is provided in Response #3 to Carl Jensen above. STOP signs are currently provided on both the northbound and eastbound approaches to this three - legged intersection. A traffic light is not warranted at this location based on either vehicular or pedestrian volumes. While crosswalks could be provided on either or both the west or south legs of the 53rd Avenue S. /S. 160th Street intersection, their value relative to pedestrian safety is dif- ficult to define. While they clearly mark the location where pedestrian crossings are designated, they can also provide a false sense of security for pedestrians who assume that they are safe only because they are in a designated crosswalk. The level of expected pedestrian activity does not warrant consideration of an overpass at this location. Given the expected traffic volumes, expected pedestrian volumes and the suggested shoulder widening along S. 160th Street and sidewalks along 53rd Avenue S., pedestrian travel should generally be safe. However, it is acknowledged that the potential exposure to conflicts between pedestrians and autos generally increases with any increase in either component. 20. Corrected distances to park and recreation facilities in the area are pro- vided in the revised Parks and Recreation Section of the FEIS. Response to comments made by Robert Crain 21. See previous responses to the letter from Robert Crain. Response to comments made by Bernie Onorati 22. The question of whether the proposed residential units are sized appropriately for the market is beyond the scope of this EIS. 289 Response to comments made by Robert Christensen 23. It is acknowledged that travel and parking patterns may be affected by snow fall associated with slippery /icy roads in the project vicinity. It is not expected, however, that substantial off -site parking will be sought since grades on adjacent area streets are typically between 5 and 20 percent com- pared to a maximum grade on the project site of 15 percent. It is thus unlikely that access from the adjacent streets to and from the project site would be perceived as any more difficult than travel off the hill in general. 24. The TRANSPO Group based its traffic distribution pattern on a variety of factors, including the orientation of the site relative to the primary streets, the location of employment and retail centers, as well as schools and social /recreational opportunities. In addition, a variety of travel purposes must be considered. These include the worker commute trip which typically occurs during peak periods, and thus is typically oriented to the major traffic arterials and freeways to provide access to the variety of employment locations; social /recreational trips which typically disperse in a wider yet more locally destined pattern; retail trips which are split bet- ween community /convenience retail such as that found to the west and south in the McMicken Heights area and comparison retail which is typical of that found at Southcenter; school trips which are destination specific with respect to the particular schools involved, and general miscellaneous trips which comprise the remainder of travel purposes. Of these the largest per- cent is generally associated with the commute trip, which commonly repre- sents about 35 percent of the daily travel associated with residential dwellings of this type. On the other hand, school trips comprise only about eight percent of the total daily travel associated with a development of this type. The eight percent referenced above refers to persons, not vehicles. Of this eight percent, only a small fraction would be reflected in actual vehicle trip generation. Thus, it is not anticipated that 160th via 54th Avenue South will be substantially utilized as a travel route. Again, however, it is recognized that some travel will occur via this route; as mentioned, the traffic analysis purposely over- assigns the principal transportation corridors to assure that impacts at these locations would not be underestimated. 25. Approximately 68 percent of the existing vegetation would be removed from the site. As indicated in the FEIS, plantings of rye and clover or ivy will be used to stabilize disturbed portions of the hillside. Additional landscaping is proposed throughout the project as per the landscape plan, which must be approved by the Board of Architectural Review. 26. Based on the forecasted traffic volumes for 54th Avenue S. near Slade Way, including that traffic element which could be attributed to the construction of the Valley View Estates project, rebuilding 54th Avenue will be reviewed by Public Works. The project sponsor has not agreed to agree not to protest formation of an LID to upgrade vicinity roads to current City standards. 27. As indicated on pages 8 through 11 in Appendix E, no accidents were reported for the period from 1980 through September 1983 at the intersection of 53rd 290 Avenue South and South 160th Street according to records supplied by the King County Traffic Engineer and the City of Tukwila. It is acknowledged that the two -way STOP /three - legged intersection configuration at South 160th and 53rd Avenue South is unusual, and thus may cause some motorist confusion regarding who has the right -of -way and what the intended travel path of vehicles approaching the intersection are. Since the north and west legs comprise the major movement at the intersection by an approximate factor of 10, conversion of the control at this intersection to a typical T- intersection STOP control with only the west leg controlled by a.STOP sign does not appear reasonable. Further STOP control to include STOP signs for the southbound approach on the northern leg may eliminate some confusion for some drivers; however, the current accident records would not indicate this change is warranted. As indicated on pages 20 and 21 of Appendix E, the overall peak hourly average operation level of service during the busiest time of the day would indicate that the northbound approach on 53rd Avenue South (i.e., left turns and right turns) would operate in the LOS D range with or without the pro- ject in 1987. As TRANSPO's manual peak hour counts indicated, there are periods within the peak hour when delays and traffic queues associated not only with the northbound approach but with the left turn from the westbound approach backup in excess of 10 vehicles. As indicated, the incremental difference in traffic queuing as a result of project - generated traffic would seldom be noticeable. Based on an examination of both existing and fore- casted traffic volumes entering this intersection, it does not appear that a traffic signal is or will be warranted in 1987 with or without this project according to the traffic signal warrants set forth in the Manual on Uniform Traffic Control Devices (MUTCD) published by U.S. Department of Transportation, Federal Highway Administration. This manual provides guide- lines for transportation professionals as it relates to the installation of such devices. Installation of unwarranted traffic signal devices can cause needless delay to vehicles on major through streets as well as increase cer- tain types of accidents. Response to comments made by Calvin Johnson 28. The Earth and Water sections of the FEIS and /or the GeoEngineers, Inc. geotechnical /hydrological report (Appendix A) has generally been modified to adequately include and /or address the concerns raised by this comment on the DEIS. 29. According to the FEIS,, on a peak day water consumption for the entire pro- ject could reach .04 mgd per day. Average consumption would be 90 gallons per unit per day (see Water section in Appendix G). Projected sewage flow also is 90 gallons per day per unit with a projected peak flow of .05 mgd. The existing 12 -inch sewer line would be adequate to accommodate these flows. 291 Response to comments made by Richard Goe 30. Figure 1 has been revised to show South 163rd Street. 31. The estimates referred to are in reference to the daily traffic volumes depicted on Figure 3. The estimates were derived from the manual peak hour counts conducted by staff of the TRANSPO Group during August of 1983. The ratios between evening peak hour conditions and the daily traffic volumes indicated as estimates are consistent with the ratios between peak hour and daily volumes found on nearby streets and intersections where traffic data was available from the City or County. In addition, all analysis and level of service conclusions were based on the evening peak hour counts conducted directly by the TRANSPO Group. Thus, the analyses and conclusions of the study were based on first hand field data collected by the traffic con- sultant. Reference to inaccuracies or inconsistencies of the traffic study were previously addressed in Hearing Transcript Response #8 to Darlene West. 32. The steepness of the hill on Slade Way in addition to the proximity of the curves to the two project driveways are acknowledged. Likewise, it is acknowledged that if this were a high volume roadway, the potential hazard associated with driveway movements conflicting with through street movements would be of more concern. However, in the evening peak hour when traffic volumes are typically at their highest, a total of 10 outbound movements would be expected from these southerly project access driveways, most of which would be right turns rather than left turns. These movements would be subject to merge with approximately 20 non - project related cars along this section of Slade Way during the same time period. At the project driveway entering 53rd Avenue South, a total of 15 outbound trips would be expected to occur during the evening peak hour. Of these, 10 would be right turns and five would left turns. To improve sight distance for driveway exiting vehicles on this driveway, it is suggested that an approximately level plat- form extending about 30 feet from the driveway STOP line at 53rd Avenue be incorporated into the driveway design to provide a level entry into 53rd Avenue South for these driveway vehicles; thus enhancing their ability to see traffic approaching from both directions. 33. The TRANSPO Group recognizes the relative attractiveness of the area up the hill to the west for convenience items such as groceries, cleaning, phar- maceuticals, etc. This was taken into account in the analysis presented in Appendix E of the DEIS. The peak hour traffic volumes on which the analysis of level of service and delay was based assumes travel patterns more closely associated with the commute trip from work to home. Thus, the travel pat- terns associated with this time period reflect a greater orientation to the prime traffic carrying arterials and highways. During off -peak hours, more travel occurs to a wide variety of more local destinations including those locations mentioned up the hill to the west. Since the overall amount of traffic generated by this development is relatively small, TRANSPO has cho- sen to reflect impacts on only the primary traffic carrying roads in the vicinity. Page 18 of Appendix E acknowledges that traffic generated by this development would utilize other streets in the area as well; however, to reflect a worst case analysis on the primary streets, all traffic was 292 assigned to these primary roadways for analysis purposes. Actual impacts to these roadways may be less than those described in the analysis. 34. The FEIS discusses the land use implications of developing this non- conforming use, both in terms of impacts on the adjoining single family neighborhood and on project residents. The proposed multi - family project is potentially allowed in a single family neighborhood because the applicant vested his rights before the zoning on the property was changed from multiple zoning to the R -1 single family designation. The City of Tukwila has endeavored to correct identified inadequacies in the Draft EIS in this Final EIS and has required that significant new information be generated to address concerns that arose during the Draft EIS comment period. 35. The Earth and Water sections of the FEIS and /or the GeoEngineers, Inc. geotechnical /hydrological report (Appendix A) has generally been modified to adequately include and /or address the concerns raised by this comment on the DEIS. 36. GeoEngineers, Inc. has issued a revised Geotechnical and Hydrological report (Appendix A) and the text of the FEIS has been updated to better identify existing conditions and include general requirements for (i) monitoring of soil and groundwater conditions; (ii) maintenance of existing and proposed facilities; ; and (iii) posting of bonds by the developer to provide the funds for necessary mitigating measures. Refer to revised Earth Resources discussion in the FEIS. The EIS has been updated to better identify storm water discharges, flow paths, and the off -site properties that are expected to receive these discharges. The revised discussion of existing site drainage conditions, impacts, and proposed mitigative measures are presented in the section under "Water" entitled "Surface Water Movement, Quantity, Quality, Runoff /absorption of the revised EIS. 37. The basic purpose of an EIS is to disclose significant adverse environmental impacts that could result from a proposal and to identify alternatives and /or mitigation measures which could be implemented to alleviate those impacts. Based on a review of this information, as presented in the Final EIS, the decision makers (in this case, the City Building Department) deter- mine which specific mitigating measures are appropriate as conditions of project approval -- or whether the project should be denied on the grounds that significant unavoidable adverse impacts cannot be mitigated. Thus an EIS is a disclosure document, rather than a statement justifying a par- ticular action. 38. Comment acknowledged. The FEIS indicates that noise levels in the area can be expected to increase over time as freeway traffic volumes increase. According to the noise consultant, leaves on trees provide noise attenuation of approximately 3 dBA per 100 meters. 39. Comments acknowledged. 40. According to the Tukwila Fire Chief, they do not anticipate difficulties navigating fire trucks on nearby streets or reaching the site in the event 293 of a fire. Response to comments made by Eleanor McLester 42. The City of Tukwila retained the geotechnical firm of Dames & Moore to review the Draft EIS and their comments on the Draft appear in this Final EIS. Based on the needs which they identified for additional information, supplemental geotechnical work has been performed and the results presented in the FEIS. (Refer to revised Earth Resources and Water Resources sections in Part One, as well as the revised Geotechnical /Hydrology study in Appendix A). Response to comments made by Bernie Onorati 43. The recommendations of the Geotechnical Consultant may be imposed as con- ditions of permit approval. 44. As a condition of approval, the City of Tukwila will require that the City, its officers, employees, and agents be indemnified from all claims, damages, losses, or liabilities arising directly or indirectly from any earth move- ment on the site. The developer and property owners may be required to post a bond to make funds available to adjacent property owners to compensate for damages caused directly from any earth movement on the site at any time during the life of the proposed development. Although recourse to legal action may be necessary to access these funds, in the event of earth move- ment on the project site, responsibility for compensation for damages will lie with the developer and property owners. Response to comments made by John Schwarzman 45. The City will have no financial responsibility for any subsequent damages that may result from development of the site. Response to comments made by Dennis Robertson 46. City approval of the project can be conditioned to achieve noise attenuation consistent with State and Federal regulations (see revised FEIS sections on Noise and Human Health). 47. See revised FEIS sections on Noise and Human Health. 294 48. In the discussion of police services, the FEIS acknowledges that there is no guarantee that individual condominium owners might not rent out their units over time. The City does not have the authority to prevent owners from renting their condominiums. However, such a restriction could be included within the condominium covenants by the developer. There is no data available that would indicate the effect, if any, that the proposed development would have on surrounding home values. However, appro- val of a project that conforms with applicable zoning laws, (which the pro- posed condominium development does) would not be considered a "taking" or infringement of a neighboring property owner's rights, solely because it represents a different or more intensive use. Response to comments made by Dennis Robertson 49. See the comment letters on the Draft EIS from Metro and the Department of Ecology as well as the revised Sewer discussion in the FEIS. As of March 30, 1985, subsequent to the Crestview annexation, 63 percent of the housing units in the City were multi - family. This project would increase that per- centage to 67 percent. 50. Comment acknowledged. The proposed project will require garbage truck ser- vices at a minimum of one trip per week. Any increase in such truck traffic would create a corresponding increase in the risks associated with an out - of- control vehicle, however remote. 51. GeoEngineers, Inc. has issued a revised Geotechnical and Hydrological report (Appendix A) and the text of the FEIS has been updated to better identify existing conditions and include general requirements for (i) monitoring of soil and groundwater conditions; (ii) maintenance of existing and proposed facilities; and (iii) posting of bonds by the developer to provide the funds for necessary mitigating measures. Refer to revised Earth Resources discussion in the FEIS. Response to comments made by Darlene West 52. SEPA requires that the appeal of an environmental action be tied to the underlying action. The seven -day period from issuance of a FEIS is a minimum period before any action can be taken by a government official or agency on a proposal. The official period to appeal an EIS does not begin until the City acts on a permit for the project, in this case, the Board of Architectural Review. 295 PART THREE APPENDICES APPENDIX A GEOTECHNICAL AND HYDROLOGICAL STUDIES REPORT GEOTECHNICAL AND HYDROLOGICAL STUDIES PROPOSED VALLEY VIEW ESTATES SLADE WAY AND 53RD AVENUE SOUTH TUKWILA, WASHINGTON FOR DR. H. M. ALLENBACH MHENE APR 26 1985 CITY OF TUICWILA PLANNING DEPT. File No. 523 -02 April 25, 1985 GeoEngineers Incorporated Nitio GeoEngineers Incorporated (206) 881 -7900 P.O. Box 6325 2020 124th Ave. N.E. Bellevue, WA 98008 April 25, 1985 Stepan and Associates, Inc. 930 South 336th Street, Suite A Federal Way, Washington 98003 Attention: Mr. Glen McKinney Gentlemen: Consulting Geotechnical Engineers and Geologists We are pleased to submit two copies of our "Report, Geotechnical and Hydrological Studies, Proposed Valley View Estates, Slade Way and 53rd Avenue South, Tukwila, Washington ". This report was developed in two phases. The scope of services for the first phase was outlined in our proposal dated August 9, 1983, and the Phase 1 report was presented on February 17, 1984. This report replaces and supplements our Phase I report. The Phase II services consist of collecting additional data and expanding some of our previous analyses to respond to comments raised during hearings on the Draft Environmental Impact Statement. -These services were performed under a confirming agreement dated July 16, 1984 and were expanded by verbal authorization from Mr. Tom Russell, project manager for Puget Western, on several occasions. We have enjoyed working with you on this project and are looking forward to continuing our relationship during the instrumentation installation and monitoring, and construction phases of the project. Should you have any questions or need additional information, please call: GMD:JKT:da File No. 523 -02 cc: Puget Western (8) Attn: Mr. Tom Russell Yours very truly, ineers, nc. Ja) k_K. Tuttle r,.incipa1 T A B L E O F CONTENTS Page No. INTRODUCTION 1 SCOPE 2 REVIEW OF SITE HISTORY 4 SITE CONDITIONS 7 SUBSURFACE CONDITIONS 9 GEOHYDROLOGICAL AND SURFACE WATER CONDITIONS 10 STABILITY • 12 INTRODUCTION 12 DEEP- SEATED SLIDING 12 SHALLOW- SEATED SLIDING 14 CONCLUSIONS AND RECOMMENDATIONS 16 GENERAL 16 EVALUATION OF I -5 DRAIN SYSTEM 18 . SITE DEVELOPMENT 21 STRUCTURAL FILLS AND PAVING. 24 RETAINING STRUCTURES 25 FOUNDATION DESIGN 27 INSTRUMENTATION AND MONITORING 28 USE OF THIS REPORT 31 List of Figures Figure No. SITE PLAN 1 HORIZONTAL DRAIN AND WELL SYSTEM 2 EXISTING ON SITE HORIZONTAL DRAIN LAYOUT 3 CROSS SECTION A -A1 4 SCHEMATIC OF PROPOSED INTERCEPTOR DITCH 5 i GeoEngineers Incorporated APPENDIX A Page No. FIELD EXPLORATIONS AND LABORATORY TESTING A -1, FIELD EXPLORATIONS A -1 LABORATORY TESTING A -1 Appendix A Figures UNIFIED SOIL CLASSIFICATION SYSTEM AND KEY TO SAMPLE DATA LOGS OF EXPLORATION APPENDIX B Figure No. A -1 A -2 lbw A-19 Page No. INSTRUMENTATION AND MONITORING B -1 PIEZOMETRIC LEVELS B -1 INCLINOMETER DATA B -1 TABLE B -1 B -2 TABLE B -2 B -3 TABLE B -3 B-4 TABLE B -4 B-5 APPENDIX C Page No. SLOPE STABILITY ANALYSES C -1 INTRODUCTION C -1 Methodology C -1 Assumptions C -1 Selection Parameters C -3 Results C -3 Additional Analyses C -3 Dynamic Analysis C -4 SHALLOW SLIDING C -4 Appendix C Figures Figure No. CROSS SECTION FOR STABILITY ANALYSIS C -1 & C -2 ii GeoEngineers Incorporated REPORT GEOTECHNICAL AND HYDROLOGICAL STUDIES PROPOSED, VALLEY VIEW ESTATES SLADE WAY AND 53RD AVENUE SOUTH TUKWILA, WASHINGTON FOR DR. H. M. ALLENBACH INTRODUCTION This report presents the results of our geotechnical and hydrological studies of the site proposed for construction of Valley View Estates. The report replaces and supplements our report dated February 17, 1984. Revisions to the report include additional water level data obtained since issuance of the initial report. We also address, in expanded detail, specific issues raised during review of the Draft Environmental Impact Statement. The site is located adjacent to the west right - of-way for Interstate Highway No. 5 and is bounded on the south by Slade Way and on the west by Slade Way and 53rd Avenue South, as shown on the Site Plan, Figure 1. The proposed development includes construction of 18 six -unit residential structures together with associated roadways, parking areas and utilities. The units will be stepped into the hillside, requiring varying depths of cut. Some cutting and filling will also be required to construct the roadways and parking areas as well as to establish reasonable grades around the various buildings. Wood frame construction which will result in relatively light foundation loads is planned. The proposed residential property is located within a very large, prehistoric, landslide zone. Also, a substantial portion of the property was involved in the landslide which occurred in 1960 as the result of excavation of borrow material which was used for fill in the Andover Industrial Park. The stability of this and adjacent properties on the southwest portion of the interchange of the freeway with State Route 405 has been improved by the remedial drainage measures which were installed by the Washington State Department of Transportation (WSDOT) during construction of Interstate Highway No. 5. No evidence of recent deep— seated movement was noted during GeoEngineers Incorporated our site examinations. The WSDOT drainage facilities include systems of horizontal drains and vertical wells, a number of which exist immediately east of this property. SCOPE The scope of services for these studies was developed and executed in two phases. Phase I was developed following a meeting on August 2, 1983 of the various parties involved in assembling information for the Environmental Impact Statement for this project. Phase I reflected our assessment of the extent of study which we considered to be appropriate for this project, based on studies made for the 1960 -61 landslide by members of our staff while employed with Dames & Moore and a review of existing surficial site conditions by our firm in 1982. Our proposal for Phase I was submitted in a letter dated August 9, 1983. We received authorization to proceed in September 1983. The purpose of the Phase I services was twofold: 1) to develop pertinent information on soil and ground water conditions for inclusion in the Environ- mental Impact Statement, and 2) to develop further design criteria, as appropriate, for the geotechnical aspects of the project. The Phase I scope of services includes: 1. Exploring subsurface soil and ground water conditions by drilling a series of test borings from which representative soil samples were obtained and in which piezometers were installed to monitor ground water conditions at appropriate levels. 2. Evaluating pertinent physical and engineering characteristics of the soils from the results of laboratory tests. 3. Reviewing information available from the Washington State Department of Transportation on the subsurface drainage system which was installed in the site area during construction of Interstate Highway 5. 4. Defining, to the extent possible, past landslide history of the immediate area. 5. Evaluating the overall stability of the project site for present geotechnical and hydrological conditions. 2 GeoEngineers Incorporated 6. Evaluating pertinent design criteria for the geotechnical elements of the project, including stability of cut and fill slopes, design criteria for shallow foundations, retaining structure design criteria, earthwork procedures, and site drainage requirements. In addition, our scope of services for Phase I was expanded to include the installation of a slope indicator casing and obtaining an initial set of readings at Boring F. This installation has been made in an area of past sliding, but lies above the area of planned development so that information from subsequent readings will provide a means of monitoring any movements of the hillside in the area between Slade Way and the planned residential development. The Phase II scope of services was developed following public hearings on the Draft EIS. The scope of services was developed with Mr. Tom Russell, project manager for Puget Western, Inc. and was authorized verbally. The purpose of the Phase II services is to gather additional information on the geohydrologic regime in the hillside and to respond to comments on the Draft EIS. The Phase II scope of services includes: 1. Obtaining an additional set of readings of the piezometers and the slope inclinometer. 2. Flushing out several piezometers installed by others adjacent to the site during investigations for the construction of I -5. 3. Obtaining additional information on the Washington State Department of Transportation well system including sounding the depth and recording the water levels in the wells. 4. Reviewing the Phase I assessment of the geohydrologic regime on the hillside with regard to the additional water level data. 5. Conducting additional static stability analyses to evaluate the stability of the hillside relative to pre- and post -drain installation and to develop criteria for identifying the extent to which water levels in the hillside . can safely rise before remedial drainage measures would need to be initiated. 6. Conducting dynamic stability analyses to evaluate the hillside stability under earthquake conditions. 3 GeoEngineers Incorporated 7. Expanding our Phase I recommendations for monitoring and instrumen- tation of site stability prior to, during, and following construction. REVIEW OF SITE HISTORY The review of the site history included examining files of the Washington State Department of Transportation in Olympia and various soils reports pertaining to the site specifically and to the adjacent slope stabilization measures accomplished during I -5 construction. The soils reports that were reviewed include: "Report of Stability Investigation, Borrow Area Slide, 54th Avenue South and South 162nd Street; Tukwila, Washington ", by Dames & Moore, December 1, 1960. "Report of Soils Investigation, Earthslide, South 162nd Street Near 53rd Avenue South, Tukwila, Washington ", by Dames & Moore, June 27, 1961. "Report on Foundation Investigation, Existing Slide Area, Tukwila Interchange, PSH -1 (SR5) ", by Shannon & Wilson, June 12, 1964. "Summary Report, Slope Stability Investigation, Tukwila Interchange (SR5) ", by Shannon & Wilson, April 14, 1966. "Summary Report, Soil Conditions and Earth Movements, Vicinity of the Tukwila Interchange ", by Shannon & Wilson, June 21, 1968. "Geotechnical Design Consultation, Proposed Residential Development, Slade Way and 53rd Avenue South, Tukwila, Washington ", by GeoEngi- neers, May 3, 1982. The listed reports document a large earthslide that occurred at the site in 1960 as material was being excavated from a borrow area immediately downslope of the site. The extent of the slide is well documented in the 1960 and 1961 reports and is shown in Figure 2. The slide covered the southern two- thirds of the site as well as extending another 200 feet upslope from the western boundary of the site. Measurements during October 1960 indicated that the slide area was moving an average of 0.5 feet per day. Movements continued at a diminished rate in 1961. Slope indicator measurements taken in conjunction with the Dames & Moore studies indicated that movements were occurring in a shear zone 25 4 GeoEngineers Incorporated to 40 feet below the ground surface through the central portion of the slide. In addition, the shear zone was indicated to consist of clayey soil underlain by a layer of waterbearing sand. The 1960/61 slide movement had resulted from the combined effect of excavation and the substantial artesian pressures existing in the waterbearing sand layer. The remedial measures considered were based on reducing the hydrostatic pressure within the waterbearing sand layer which appeared to immediately underlie the failure surface. Deep wells as well as horizontal drains and drainage trenches were considered. A series of horizontal drains was installed in the summer of 1961, together with some regrading of the borrow pit area. A plan from the Shannon & Wilson 1964 report showing the locations of the horizontal drains is presented in Figure 3. Altogether, 20 6- inch - diameter slotted pipe drains with lengths from 100 to 150 feet were installed. Eight of the drains were located along the toe of the roadway fill in the southwest corner of the site, while the remainder were located in the south - central portion of the site. The flow from the drains does not appear to be piped and is probably responsible for some of the existing wet areas at the site. The 1966 and 1968 reports are related to the overall stability of the hillside, both to the north and below this site, as it related to con- struction of the I- 5/SR405 interchange and related roadways. At that time there had been considerable landslide activity not only at the project site but north and northwest along the hillside. Ten to twelve landslides of various dimensions were observed in these areas. The 1968 report shows several recent slide scarps at the project site. With one exception, all of these were less than 200 feet long and were aligned along the contour; however, one was approximately 700 feet long and was aligned approximately at 45 degrees to the contours in the northern third of the site. This scarp appeared to be the northern boundary of a large slide, possibly the 1960 -61 slide. The proposed remedial measures consisted of an extensive subsurface drainage system of vertical wells tied into horizontal drains and cylinder pile wall retaining structures as shown in Figure 2. In addition, an inter- ceptor drain, shown as the D -3 drain on Figures 2 and 3, was installed. 5 GeoEngineers Incorporated These remedial measures were initiated by the Washington State Department of Transportation and were subsequently monitored and reported on by Shannon & Wilson. The WSDOT drain system consists of a series of 5- foot - diameter wells tied into horizontal drains originating at the retaining wall along Klickitat Drive, as shown in Figure 2. The wells are located just east of the site. In addition to the large diameter wells, a number of small diameter vertical drains were installed in between the large wells as shown in Figure 2. Based on information in the Shannon &Wilson reports, the horizontal drains consist of 1 -1/2- inch - diameter unperforated plastic pipe with 10 -foot- long stainless steel well point tips. In addition, it was recommended that every fifth drain have a section of stainless steel screen at mid- length. We have not located any records that verify whether or not this was done. Information, including elevations, grades and lengths of the WSDOT horizontal drain and vertical well system, is presented in Table B -4 in Appendix B. Based on inspection of the wells, it appears that the original pumps are still in place in approximately 70 percent of the wells. The pumps and outlet pipes have been removed in the other wells. The condition of the in -place pumps is not known. Inspection of the outlets of the horizontal drain system revealed 42 outlets through the cylinder pile retaining wall along Klickitat Drive (see Figure 2). The length and orientation of any drains in these outlets other than those that lead to the wells is unknown. There may be short horizontal drains to drain immediately behind the wall or replacement drains to the wells. The extra outlets may also be weepholes, to drain the zone behind the wall. Approximately half of the 42 drain outlets, primarily to the north, . were dry at the time of our most recent visit (April 12, 1985). Flow through the other weepholes varied from a drip to about one gallon per minute. There was also significant flow between the wall panels in two places. At one location, the flow between the panels was estimated to be 4 to 6 gallons per minute. The 1968 Shannon & Wilson report also identifies a system of original test drains that were installed by WSDOT just east of the eastern property line and south of the horizontal drain /vertical well system (see Figure 2). 6 GeoEngineers Incorporated Our examination of the portions of this drain system still in evidence indicates that they are still at least partially functional. These drains consist of 1 -1/2- inch - diameter PVC pipe. The outlets are connected to buried manifolds, three of which discharge into a drainage gully. The fourth manifold was unable to be located. Approximately 60 percent of the drains were located, of which approximately 20 percent appear to be damaged and in need of repair. Local sloughing and erosion has occurred at the drain outlets in several places. Flows from the three manifold outlets ranged from approximately 0.25 to 3 gallons per minute. The 1966 Shannon & Wilson report summarizes potential failure modes for the landsliding on the hillside and, like the 1960 and 1961 studies by Dames & Moore, concludes that the mode of failure at the project site is due to the presence of a clayey silt underlain by sands with artesian pressures. The report includes classification and average strength values for the important materials in the hillside. These data were used in our studies. The Shannon & Wilson report concludes that the I -5 project area slopes (including the area in which the drains and wells are installed) are stable for the static conditions then (1968) existing. They also concluded that the soil materials in the slopes "are unlikely to be significantly affected by seismic activity ". Some evidence of near - surface movement, mostly in the form of shallow creep and flow slides, was noted in our examination of the site prior to preparing our consultation report of May 3, 1982. A recent scarp was observed a short distance east of Slade Way. The scarp is about 200 feet long and varies from about 12 to 20 inches in height. The downslope extent of the slide appears to be limited to the upper portion of the property in which no construction is planned. The slide was estimated to have occurred in 1981 or earlier, based on the extent to which vegetation had reestablished itself along the scarp. SITE CONDITIONS A plan of the site is shown in Figure 1. The site covers approximately 7 acres and is non - uniformly shaped; being bounded on the south and west 7 GeoEngineers Incorporated by Slade Way and on the east by the Interstate Highway No. 5 right -of -way. A sanitary sewer runs along contour through the eastern portion of the site. There is also evidence of the D -3 drain, as shown on Figure 2. The site slopes moderately to the east and northeast with isolated' areas becoming moderately steep. A large drainage swale transects the southern portion of the site, resulting in the sewer alignment curving to the west around this swale before swinging to the northeast. There are three benches on the site that appear to be manmade. The presence of the benches may be indicative of remedial grading following previous slide activity. The lowest bench appears to have been constructed during the installation of the sanitary sewer line and essentially follows the sewer alignment to a point where the sewer line crosses the property line at the center of the eastern property line. The ground surface downslope from the sewer bench in the southeast corner of the site is moderately steep. A second bench starts at the southern property line slightly upslope from the sewer line bench and is oriented approximately parallel to the sewer line bench for approximately one-third the length of the site at which point it disappears. The third bench is located in the center of the site and may have been constructed during installation of an old surface drain in this area. Vegetation consists of areas of very dense berry vines, some exceeding 10 feet in height, fairly dense alder groves, scattered evergreen trees, particularly on the western portion of the site, and occasional horsetails, which are indicative of wet ground. Most of the alder trees located on the middle to eastern portion of the site appear to be fairly young, indicating that the site was likely stripped of vegetation following the slide in 1960 -61. Wet surface conditions were observed over much of the site during our field explorations in October 1983. Some of these appear as seeps or springs, possibly originating from the horizontal drains installed in 1961 as shown on Figure 3. A corrugated metal pipe stormwater drain is located at the intersection of Slade Way and South 160th Street and is reported to parallel 53rd South for a short distance before turning east and tying into the D -3 drain. 8 GeoEngineers Incorporated The drain was leaking several gallons per minute at the time of our explor- ations. Flow from this drain was apparently being collected by the upper portion of the D -3 drain. SUBSURFACE CONDITIONS Subsurface conditions were explored at the site by drilling 8 borings using a truck- mounted, hollow -stem auger drill rig. The borings were drilled during October 13 to October 21, 1983. Because of wet conditions at the site and relatively steep slopes, a dozer was required to assist the drill rig in moving around the site. An engineer from our staff established the boring locations, maintained logs of the explorations, and obtained relatively undisturbed samples for observation and laboratory testing. The boring locations, as subsequently surveyed by Stepan & Associates, Inc., are shown on Figure 1. Details of the field explorations, along with the boring logs edited to reflect laboratory examination and testing, are presented in Appendix A. Piezometers were installed in all borings except Boring F where an inclinometer casing which will permit future moni- toring of slope movements was installed. Both deep and shallow piezometers were installed in Boring J. Details of the piezometer and inclinometer instrumentation are presented in Appendix B. Subsurface conditions at the site were interpreted from borings in the 1960 and 1961 investigations and from the current drilling program. Three major units were identified at the site as follows: UNIT A: Fill and /or slope debris, probably native to the site and consisting of loose to medium dense silty fine to medium sands. Thickness varies between 5 and 10 feet. UNIT B: Gray silt interbedded with fine to medium sand. The gray silt varies in consistency between medium stiff to very stiff, generally becoming stiffer with depth. The silt has some zones which contain a trace to some clay. Slickensides are present throughout the unit as well as randomly oriented contacts between different gradations of materials. The sand layers appear to vary from 1/8 of an inch to one to two feet in thickness and are generally saturated. 9 GeoEngineers Incorporated UNIT C: Gray sandy silty gravel and gray gravelly sand with some silt. Consistency varies from dense to very dense and unit is generally saturated. Unit B generally grades into Unit C and is separated by a layer of gray fine to medium silty sand in some of the borings. The three units vary significantly both in depth and elevation across the site. As shown in a typical cross section in Figure 4, the units tend to follow the existing topography and slope down to the east.. The thickness of the gray silt (Unit B) is less toward the south (25 feet in Boring C) and increases to the north (89 feet in Boring K). The dip of the surface of Unit C is to the northeast and may represent an erosional feature that occurred before deposition of Unit B. GBOHYDROLOGICAL AND SURFACE WATER CONDITIONS Two separate and independent hydrologic regimes exist at the site. The upper regime, existing within Units A and B, is influenced by surface water runoff, seepage from upslope, and direct precipitation. Seepage volumes are small due to the relatively low permeability of these soils. Water pressures in this regime are likely to be hydrostatic. In contrast, the lower regime existing within Unit C is influenced primarily by subsurface ground water flow. The source of water is not known; however, it is likely that it is upslope and to the west or southwest of the site. Water pressures in this regime were artesian at the time of the 1960 -61 slide. The permeability of the soil in the lower regime (Unit C) is significantly higher than the soils in the upper regime and seepage volumes would be expected to be cor- respondingly higher. The original water table at the site has been modified on three occasions in the past 25 years. The first modification occurred after the 1960 -61 slide when several on -site horizontal drains were installed in 1961 on the slope (see Figure 3). These were installed to alleviate the artesian pressures in Unit C and arrest the hillside movements. The second modification of the water table at the site occurred in 1966 when the Washington State Department of Transportation installed a 10 GeoEngineers Incorporated (' series of large- diameter wells (see Figure 2). These wells were then pumped during construction of a cylinder pile wall along Klickitat Drive to the east of the project site. The third and most recent modification of the ground water regime occurred near the end of construction of the cylinder pile wall when horizontal drains were drilled to intercept the vertical wells and the pumps in the wells were subsequently switched off. Water levels in the two ground water regimes were measured using the piezometers installed in our borings in October 1983, three of the piezometers installed by Shannon & Wilson in 1966 which we were able to locate, and the WSDOT vertical wells. Our piezometers are installed in Unit C, the lower ground water regime, with the exception of the second piezometer in Boring J which was installed in Unit B, the upper ground water regime. The piezometer levels in our borings were originally measured on November 18, 1983 and subsequently measured on three occasions between November 30, 1984 and March 12, 1985. These data are presented in Table B -1 in Appendix B. Several readings of the Shannon & Wilson piezometers and the WSDOT wells were also taken during this period. These data are presented in Tables B -2 and B -3 in Appendix B. The Shannon & Wilson piezometers were flushed in March 1985. The piezometric data collected from November 1984 to March 1985 indicate relatively stable water levels in the lower ground water regime (Unit C) at the site. Water level depths range from 29 to 77 feet below the ground surface at the site and 26 to 55 feet as measured in the Shannon & Wilson piezometers east of the site. The water level data from the WSDOT wells is less consistent and it appears that several wells or horizontal drains are plugged. This is discussed further in the section on "Evaluation of I -5 Drain System ". In the upper ground water regime (Units A and B), the water levels are expected to be variable, ranging from the ground surface to depths of ten or more feet, depending largely on local topography, seasonal rainfall, and other factors. In Piezometer J, the water depth has been stable over the last six months at a depth of 9 feet. 11 GeoEngineers Incorporated STABILITY INTRODUCTION The purpose of the stability analyses is to assess the risk of instability of the hillside. The risk of sliding is related to existing conditions and to the effects of changing water levels in the hillside, as well as to earthquake activity. The analytical procedure consists of evaluating the gravitational force driving the soil downslope and the force of the soil (strength) resisting the sliding. The procedure also takes into account the effects that ground water conditions have on the resisting force. In general, the higher the water levels in the slope the lower the soil strength or resisting force. The risk of slide movement is expressed as a factor of safety which is defined as the ratio of the resisting force divided by the driving force. If the resisting force equals the driving force, the factor of safety is 1 and the risk of sliding is very high, whereas if the resisting force is greater than the driving force, the factor of safety is greater than 1 and the risk of sliding decreases as the factor of safety increases. Generally, slopes having a factor of safety greater than 1.5 are considered to have an acceptably low risk of sliding and are considered to be stable. Stability analyses were conducted to analyze both deep- seated and shallow- seated sliding. Details of the analyses including figures showing the failure surfaces analyzed are presented in Appendix C. A brief description and summary of the results of the analyses is presented below. DEEP- SEATED SLIDING The stability of the hillside was evaluated by considering the different topographic and ground water conditions which existed during the 1960 -61 slide and which exist in March 1985. The alignment of the section judged to be most critical of those analyzed is shown on Figure 1. The first set of analyses was conducted by assuming topographic and water level conditions recorded in 1960 and 1961 and back calculating the soil strength parameters required to yield a factor of safety of 1.0. 12 GeoEngineers Incorporated The soil strength parameters so determined are in good agreement and fall within the range of values reported by Dames & Moore and Shannon & Wilson and used in their analyses. The key parameter is the friction angle in the failure zone. The actual values used are as follows: Soil Along Soil Above Failure Zone Failure Zone 0 C 0 C GeoEngineers, Inc. Shannon & Wilson, Inc. Dames & Moore 0 = friction angle in degrees. C = cohesion in psf. 15 0 14. 0 14 600 25 0 22° 700 35° 0 The parameters determined in our studies were then used to analyze the slope stability for the March 1985 topographic and water level conditions inasmuch as we judge them to be a reasonable median value of the three sets of parameters reported. The results of these analyses indicate that the factor of safety of the hillside for current conditions is in the range of 1.5 to 1.6 for the sections analyzed. The increase in factor of safety is, in our opinion, primarily due to the decrease in water levels caused by the WSDOT drain system, and represents an acceptable factor of safety in relation to the planned project. The impact of building loads on overall slope stability was also evaluated and found to have a negligible influence on the factor of safety. The possibility of a decrease in the factor of safety with a rise in the water level resulting from deterioration of the drainage system was also evaluated. The results of this evaluation (see Appendix C) indicate that the risk of sliding would become very high, i.e. FS = 1.0, if the water table were to rise an average of 20 feet above the March 1985 levels in the lower artesian aquifer. (See Tables B -1, B -2 and B -3.) The stability of the hillside was also evaluated for earthquake condi- tions. For this condition, the ground shaking during the earthquake increases the driving force. The seismic increment was approximated in the analysis by an equivalent static force proportional to a nominal horizontal ground acceleration (pseudo static method). For the project area, a horizontal 13 GeoEngineers Incorporated ground acceleration of 0.15g, where g is the acceleration due to gravity, was assumed. This value is typically used for seismic design in the Seattle area. It should be noted that the factor of safety calculated using the pseudo static method has a different connotation from that for static loading. Specifically, for the soil conditions which underlie the project site, a factor of safety of 1 or less represents a very high risk of sliding only during the ground shaking period. When the shaking ceases, movements should effectively also cease. This correlates with the observations of movements reported by a local resident upslope of the site after the 1965 earthquake. The actual amount of straining or displacement will depend on specific site and earthquake characteristics as well as the soil and ground water conditions. For the earthquake analysis, the shear plane was considered to have an additional strength component equal to 500 pounds per square foot of cohesion. This additional strength component is representative of the undrained soil conditions which would exist during the short -term cyclic loading. A factor of safety of 1.13 was computed using the indicated earthquake loading and undrained strength parameters. This value is considered, in general practice, to provide a level of risk comparable to a factor of safety of 1.5 for static conditions. SHALLOW - SEATED SLIDING Slope stability due to shallow- seated sliding was evaluated using an empirical /infinite slope approach. This approach is based on reviewing existing slopes at the site and then analyzing different water level conditions, assuming a uniform infinitely long slope of similar material. Slope con - figurations at the site vary from about 2H:1V (horizontal to vertical) to 4H:1V. Perched water levels (upper regime in Units A and B) are variable across the site, ranging from the surface in areas below springs or flow from old horizontal drains to 9 feet (Boring J), or deeper. In some areas, evidence of surficial creep, as expressed by bending in tree trunks as they have grown, on the flatter but wetter slopes, indicates a lesser degree of stability than steeper, well- drained slopes on the site. 14 GeoEngineers Incorporated The importance of control of water levels on near - surface stability is illustrated using a 3H:1V continuous slope, the soil strength (0 = 250) assigned to the upper soils in the analysis of deep- seated stability and varying the perched water level. The effect of water level conditions on the factor of safety against sliding (ratio of resisting force to driving force) is shown in the following table. Perched Water Level at ground surface 6 feet below ground surface 12 feet below ground surface Factor of Safety 0.7 1.1 1.4 The recommended final slopes for the site are 3H:1V or flatter. It is our conclusion that the stability of the slopes can be maintained at acceptable levels, provided that adequate drainage of the slopes is accomp- lished. The types of drainage facilities to be installed include an interceptor trench along the western property line, surface drains, a gully French drain, parking area French drains, subsurface wall drains and downspout drains. The extent of each of these facilities which should be installed to develop adequate drainage is discussed subsequently. The actual building loads will have a small favorable effect on the shallow slope stability, as the friction angle of the underlying soil is greater than the overall slope angle and the added vertical load will increase the resisting force more than the driving force will be increased (provided the load is applied slowly so that pore pressures are allowed to dissipate which is assumed to be the case for the type of construction and soils considered). There may be some destabilization of slopes during construction if slopes are oversteepened or adequate shoring is not used. Remedial measures including temporary backfilling, buttressing or otherwise increasing toe resistance may have to be initiated. Dynamic loading during an earthquake decreases the stability of slopes and may result in movement of any marginally stable slopes around the perimeter of the project. As described previously, the sliding should be limited to the duration of the earthquake. Resistance to sliding of individual structures requires analysis on a site - specific basis. This analysis should 15 GeoEngineers Incorporated be conducted by GeoEngineers, Inc. and the appropriate corrective measures recommended for inclusion in the design during the preparation of the final plans. CONCLUSIONS AND RECOMMENDATIONS GENERAL We conclude that development of the property as planned is feasible providing that maintenance of the WSDOT drain systems to the level required to maintain or improve present performance is accomplished and that the recommended near - surface drainage measures are accomplished as subsequently discussed on pages 22 and 23. Development of the site will be difficult due to the marginal stability and saturation of the near - surface soils. Close coordination between the earthwork contractor and the engineer will be required to see that our recommendations are diligently followed, as subsequently discussed on page 22. There are two principal mechanisms of slope instability which could affect the property. These include deep- seated sliding in a zone of soil from 30 to 50 feet below the surface and surficial sliding in the upper unit of soil, generally extending to a depth of about 10 to 12 feet below the present ground surface. The potential for movement of the hillside in the deeper zone of soils is largely controlled by the continued satisfactory performance of the vertical well /horizontal drain system which was installed during construction of Interstate Highway 5. It is also controlled to a lesser degree by the "Original Test Drains" which were installed south of the vertical well /hori- zontal drain system. From our review of available information, it appears that the overall site stability in the approximately 20 years since these drains have been constructed has been good and that the drainage system continues to be generally effective in preventing deep- seated movements. It is of prime importance, however, that both of the WSDOT drain systems remain fully operational. If the drainage systems should deteriorate so that artesian pressures can again increase beneath the hillside, the risk of deep- seated and extensive earth movements can be expected to significantly increase. 16 GeoEngineers Incorporated The second mechanism of shallow- seated movements is largely affected by surface runoff and near - surface infiltration of rainfall and runoff from higher ground. Based on the approximately 200 - foot -long scarp that was observed in 1982 and considered to be indicative of recent movement, it is evident that this potential for surficial movements is still relatively high in the southern portion of the property. We recommend that surface and near - surface drainage on the site be improved by constructing an interceptor ditch along the westerly limits of the property adjacent to Slade Way, together with installation of various drainage facilities in connection with site grading and building construction which are discussed subsequently. The piezometers and slope indicator which have been installed as a part of this investigation form the basic components of an instrumentation program to monitor long -term behavior of the property. We recommend that this instrumentation program be expanded prior to construction. Additional slope inclinometers and piezometers should be installed at locations where they can be protected and remain functional, both during and following construction. A series of hubs should be installed above areas where cuts are planned. The hubs should be initialized (surveyed in) immediately and monitored on a regular basis thereafter. The system of piezometers and the inclinometer currently in place should also be maintained and monitored on a regular basis. Some of the new piezometers may have to be located to replace existing piezometers which may be lost in construction activities. A long -term monitoring program to be accomplished under the direction of (or by) our firm is recommended. We consider such a program essential to detect any changes in effectiveness of the WSDOT and on -site drainage systems so that early remedial action can be taken if needed. The extent of the recommended instrumentation program is described in a subsequent section. Earthwork on this property will be very difficult. We recommend that site grading be undertaken during the late summer -early fall months when the least amount of rainfall can be expected and surface runoff and seepage in the upper soil units should be diminished. Depending upon the overall construction schedule for the project, it may not be possible to accomplish all earthwork and drainage- related activities as well as foundation construction 17 GeoEngineers Incorporated in a single dry season. Therefore, we strongly recommend that construction activities be scheduled so that site grading, drainage installation and surface stabilization, if not final paving, are completed in any given area within a single construction season. Construction should also be phased, as described subsequently, to minimize the impact in any one area. No area should be left partially graded or without proper surface drainage, as this may endanger the near-surface stability of that portion of the site if left through the wet seasons. Several of the planned structures are shown located above the existing sewer (see Figure 1). We understand that the sewer alignment may be changed so that it no longer is located below the structures. However, special foundation preparation procedures, as described on page 25, will be necessary along the sewer alignment to provide uniform bearing support for the structures. A major drainage way intersects the site in an east -west direction through the center of the site. It is important to maintain provisions for drainage along this gully alignment. Accordingly, we recommend that a French drain be installed along the base of the gully as shown in Figure 1 before any filling is accomplished. EVALUATION OF I -5 DRAIN SYSTEM The operational life of horizontal drains is not well known. Depending on the soil type into which the drain is installed, the installation method and other factors, drains may operate satisfactorily for many years. However, drains are also known to silt up or clog due to corrosion or algae and bacterial growths within the slotted sections of pipe. This can result in major, if not total, loss of operating effectiveness after a few years. There appear to be no data available to assess periodic changes in performance of the WSDOT drain systems over the last few years. However, there are records of the water levels during the period December 1966 to June 1968 for several piezometers located immediately east of the site. There are also records of our piezometers from November 1983 through the present, and recent records of the water levels in three Shannon & Wilson piezometers 18 GeoEngineers Incorporated and in the WSDOT wells (see Tables B -1 through B -3). Although the data are seasonal and precipitation varies on an annual basis, we believe that there is a sufficient data base on which to evaluate the effectiveness and degradation of the WSDOT drainage system. The locations of the piezometers for which data are available during the period December 1966 to June 1968 are shown in Figure 2. The piezometric elevations before and after drain installation during this period as well as the March 1985 readings are tabulated below: PIEZOMETRIC ELEVATIONS (FEET) IN SHANNON & WILSON PIEZOMETERS PRE AND POST I -5 DRAIN SYSTEM INSTALLATION Pre Drain Post Drain Piezo- Tip Water Water Elevation meter Elevation Elevation Dec. 66 Oct. 67 June 68 March 85 lA 85 155 101 92 90 93 1B 100 115 109 97 100 111 19 52 149 111 111 122 N/L 232 49 72 65 60 77 N/L 1 80 162 103 102 110 139 2 86 153 130 122 123 N/L 3A 90 137 105 99 120 N/L N/L - Not able to be located. The tabulated data indicate that, with the exception of Piezometer 232, the piezometric surface was lowered between 15 and 65 feet approximately 3 years after installation. Since that time (June 1968.) to the present, the water levels in the three Shannon & Wilson piezometers which we were able to locate indicate a rise of 3, 11 and 29 feet in Piezometers 1A, 1B, and 1, respectively. This indicates some degradation in the drain system; however, it may be related in part to the fact that the drains have not yet been cleaned out by WSDOT in 1985 (as of April). A similar comparison may be made of the water levels in Borings DM -1 and DM -3 from the Dames & Moore June 1961 report and Borings D and G in this study just inside the east property line of the site. This comparison is based on water levels at the time of the slide and at the present (March 19 GeoEngineers Incorporated at regular intervals, changes in water levels can be detected and appropriate remedial measures may be implemented. The multiple well groups and horizontal drains provide a redundancy to the system. Also, some of the flow appears to have found other paths, possibly along the outsides of some drains, as evidenced by the flow through the panels at the retaining wall. We believe that it is essential that WSDOT expend effort to flush the horizontal drains and restore the effectiveness of the wells. If nothing is done, the drain system will continue to deteriorate, probably accelerating with time; however, if the drains are flushed and the wells cleaned and redeveloped if necessary, the system should continue to be effective for many years. Given the importance of the WSDOT drain systems on the stability of the project site, we recommend that the following repair work and maintenance procedures be implemented by WSDOT as soon as possible. o Clean out and flush the horizontal drains. o Clean out, flush and develop, if necessary, the 24 vertical wells. o Extract the pumps after flushing. (It is likely the pumps are silted in and may not be able to be extracted without flushing.) o Sound the depths of the wells. o Secure the top plates on the wells to prevent extraneous matter from being thrown into the wells. o Repair the "original test drain" system. o Locate and document the manifold outlets for the original test drains. o Monitor the flows from both systems of horizontal drains, as well as the piezometer levels, as discussed in the section on "Monitoring." SITE DEVELOPMENT The sequence of operations required to develop the site is critical to the successful completion of the project. In view of this condition, we have developed a general sequence for site development with regard to installation of instrumentation, drainage, site clearing and grading, and construction. Only minor deviations should be permitted from this sequence and then only with the approval of the engineer. 21 GeoEngineers Incorporated The recommended site development sequence is as follows: 1. Install additional instrumentation at least two months in advance of construction, and preferably as soon as possible, to establish the preconstruction data base. (See section on Instrumentation and Monitoring for details.) Monitor instrumentation on a regular basis, to be specified at the time of installation, before, during and after construction. 2. Construct interceptor trench along west property line (see later details in this section), install temporary drainage ditches in construction -free upslope areas, and install temporary erosion control measures to pick up concentrated surface water flow, locate and tightline appropriate on -site horizontal drains. 3. Establish access road, accomplish general site clearing, install gully French drain and accomplish general site grading. 4. Perform individual structure grading on a phased basis. Alternate building areas should be graded and with the number of sites prepared limited to the number for which foundation, wall construction and backfilling can be completed during the dry season. The approximate location of the interceptor trench is shown on Figure 1. The trench should be approximately 2 feet wide and not less than 7 feet deep. It should preferably extend to the top of the gray silt which varied between 7 and 12 feet in the three closest borings. The trench should be lined with a monofilament filter fabric such as Mirafi 140N, with not less than 2 feet of overlap of adjacent sections of the fabric. A 6 -inch smooth -wall perforated pipe should be fully bedded in a well - graded sand or clean gravel at the bottom of the trench. The remaining trench backfill should be clean, free - draining sand and gravel. The filter fabric should cover the free - draining fill with a fabric overlap of 12 inches below the surface and be covered with the silty native soil. A detail of the interceptor trench is shown in Figure S. The approximate location of the gully French drain is shown in Figure 1. The drain should be installed from the downstream end working up the existing gully. The gully should be cleaned out of all organic material and debris for a width of at least 8 feet and a 3- foot -thick blanket of graded sand 22 GeoEngineers Incorporated and gravel filter placed in the gully. A smooth -wall, 8- inch - diameter perforated PVC pipe should be placed in a 12- inch -deep trench in the filter material and then covered with an additional 2 feet of the filter material. The top of the filter material should be at least 4 feet wide. The filter material should then be covered with filter fabric, as previously specified for the interceptor drain. Fill may then be placed in level lifts on either side of, and above, the filter material. We recommend that permanent French drains be installed along the upslope sides of all parking areas. These drains should be at least 5 feet below finished grades and should consist of perforated pipe fully bedded in a graded sand filter or in clean gravel which is, in turn, enclosed in a filter fabric envelope. The filter fabric should be installed with overlaps in the same manner as described above for the interceptor trench. The remaining trench backfill should consist of clean, free- draining sand and gravel. A similar drain should be installed in any wet areas to the west of the building units. Flow from these drains may be combined with flow from footing drains and downspouts for disposal in a storm drain system; however, the design of connecting pipes should be such to prevent backflow into sections of perforated pipe. We anticipate no impact on the WSDOT drain system from the proposed development if surface runoff is collected and routed off -site and surface water infiltration is minimized as recommended above. This conclusion is based on the fact that the WSDOT system services the lower aquifer and the barrier of lower permeability soils afforded by Unit B essentially precludes continuity between the upper 'and lower ground water regimes at the site. See Section on "GEOHYDROLOGICAL AND SURFACE WATER CONDITIONS" in this report. The ability to use the on -site soils for fill is expected to be limited. We anticipate that the soils in their natural state will be above optimum moisture for adequate compaction. In order to use these soils, drying will be necessary. Also, we recommend that only clean granular soils be used for fill behind retaining structures. While careful segregation of 23 GeoEngineers Incorporated the natural soils during excavation may provide some ,suitable backfill, we anticipate that much of the backfill behind the walls and for any areas of structural fill will have to be imported. Stockpiling should be limited as much as practical on the site to minimize potential impacts on slope stability and erosion. As noted, most of the on -site soil to be excavated will be unsuitable for backfill and should be immediately removed from the site. The earthwork should be sequenced to limit the size of any stockpiles. If stockpiles are required, they should be placed at the north end of the site. The size and height of the stockpiles should be determined on a specific basis as construction progresses and in coordination with our field representative. We recommend that temporary cut slopes be made no steeper than approxi- mately 1- 1 /2H:1V (horizontal to vertical) and be limited to 15 feet in height. The stability of these cut slopes will be relatively low. Our analyses indicate that the factor of safety under static, drained conditions will be on the order of 1.2 to 1.3,.assuming some short -term cohesion. Some sloughing or localized sliding should be anticipated, particularly where zones of seepage are encountered. When the excavations are made for the various buildings, we recommend that the construction be sequenced so that alternate building sites are excavated (for example, Sites 3, 5, 7, 9, etc.), retaining walls built and adequately braced, perimeter drainage installed, and backfill placed before beginning excavation for the intermediate buildings. Permanent cut or fill slopes should be established at no steeper than 3H:1V. Slopes should be seeded as soon as practical. Localized seeps which are not intercepted by the general drainage facilities may have to be drained and /or excavated and backfilled with gravel or crushed rock to resist erosion damage to slopes. STRUCTURAL FILLS AND PAVING All structural fill should be placed in relatively thin (8 to 10 inches) layers and uniformly compacted. Backfill against retaining walls, particularly those in the structures, should not be overcompacted. A compaction of 24 GeoEngineers Incorporated 90 to 92 percent of the maximum dry density determined by ASTM D -1557 should be achieved. Fill beneath paved areas or forming slopes should be compacted to 95 percent of maximum density. We understand that access roadways and parking areas will be paved with asphaltic concrete. Prior to placing base course material, we recommend that the exposed subgrade be thoroughly proofrolled. Any soft, loose or wet areas should be excavated and replaced with clean granular fill if the natural soils cannot be satisfactorily recompacted. Based on the existing surficial wet conditions, it should be expected that overexcavation and replacement of on -site soils with imported granular fill will be necessary over much of the roadway and the parking area. Overexcavation of 12 to 18 inches may be necessary for roadways and parking areas to establish a stable subgrade. All fill placed below subgrade level should be compacted to at least 92 percent of maximum dry density (ASTM D- 1557). A pavement section of 4 -1/2 inches of clean pit run subbase, 1 -1/2 inches of crushed rock base and 2 inches of asphaltic concrete should be used. The extent of overexcavation and replacement of backfill along the existing sewer in areas to be occupied by buildings should be verified by examination during construction. As a worst case condition, the following may be necessary. Fill used to replace material excavated from the sewer line trenches should consist of clean granular soil. The existing backfill should be excavated from beneath the full building area and beyond for a distance of 4 feet on both sides to a depth of at least 5 feet below the bottom of the footing or to the top of the pipe, whichever is more shallow. The first foot of backfill over the pipe should be compacted to about 92 percent of maximum dry density and the remainder to 95 percent. RETAINING STRUCTURES Retaining structures will be required for all of the buildings based on present plans. The units will be stepped into the hillside so that each section of retaining wall will be no more than one story high. The setback between walls is expected to be 15 feet or more. In addition, retention of cut slopes and fill embankments will be required along portions of the parking areas and near Unit Nos. 1 and 2. 25 GeoEngineers Incorporated We recommend that lateral pressures on the basement walls be determined using an equivalent fluid density of 35 pounds per cubic foot (pcf) times the height of the wall in feet. This value applies only if clean, lightly compacted granular backfill is used against the walls and if a perforated drain is installed along the base of the wall to prevent the buildup of hydrostatic pressure. This value also applies only where the ground surface behind the wall is level for a distance equal to the height of the wall. If a sloping ground surface exists closer to the wall, this value may have to be increased. Retaining structures along the parking area and elsewhere outside of the buildings could consist of gabion basket walls, reinforced earth structures, or conventional poured concrete walls. We recommend against the use of rockeries except possibly for protection of low (less than 5 feet) cuts into natural soils. Rockeries should not be used to retain fill embankments. Where backfill behind the walls is level, lateral pressures may be determined using an equivalent fluid density of 35 pcf times the height of the wall in feet. Where the surface slopes upward behind the wall, an increased lateral pressure must be used. If a backslope of 3H:1V exists, we recommend that the lateral pressures be determined using an equivalent fluid density of 60 pcf times the height of the wall in feet. We should review design criteria for other backslope configurations. Drainage of the backfill as well as cut slopes behind these retaining structures is critical to their stability. The lateral pressure design criteria given above is based on drained conditions. For solid structures, such as a poured wall, a zone of clean backfill and a perforated drain should be installed. If gabion basket walls are used, we recommend that filter fabric be placed beneath and behind the baskets to prevent the retained soils from washing into the relatively open work gabion rock. A perforated base drain located immediately behind the baskets is also recommended for gabion installations. Resistance to lateral loads on retaining structures may be developed by passive pressures and base friction. We recommend that passive pressures be determined using an equivalent fluid density of 200 pounds per cubic 26 GeoEngineers Incorporated foot. Base frictional resistance can be determined using a factor of 0.3 times the vertical downward component of long -term loading. These values incorporate a factor of safety of about 1.3. FOUNDATION DESIGN We recommend that the lowest floor grade of each structure be established at an elevation such that a shallow foundation system will bear directly on natural soils below the topsoil layer. We recommend specifically against supporting structures on a combination of cut and fill. It may be necessary to overexcavate and replace some of the native materials if soft, wet conditions are encountered during construction. This will probably occur all along the sewer line, as previously discussed. Overexcavation /replacement will be satisfactory providing that any fill which is placed does not extend above the original ground surface elevation. We suggest the use of a foundation system consisting of a thickened slab system that will provide more rigidity and resistance to slight differential movements across a structure than that which would be provided by continuous wall footings and a slab -on- grade system. The foundation system should consist of thickened edges around the perimeter of the slab and thickened sections beneath bearing walls within the buildings. The thickened slab system should have continuous reinforcing consisting of reinforcing bar rather than steel mesh. The thickened edge sections should extend at least 18 inches below lowest adjacent finished grade and should have a base width of at least 18 inches. The thickened edge portion of this foundation system may be proportioned using a bearing value of 2,000 pounds per square foot. This value applies to the total of all design loads including wind or seismic, but excluding the weight of the footing and any overlying backfill. Care must be taken in preparing the subgrade for the thickened slab foundation system to avoid disturbance to the bearing materials. Any seepage which is encountered should be collected and diverted from the building area. The prepared bearing . surfaces should be examined by one of our staff to determine that suitable preparation has been accomplished. It may be necessary to move and replace soft, wet or otherwise disturbed soils and to install localized drainage facilities to handle any seepage within the building area proper. Any soft soil should be replaced with clean granular 27 GeoEngineers Incorporated fill compacted to 95 percent of the maximum dry density. We recommend that the bearing surface be protected from disturbance during reinforcing steel placement and concrete pouring by placing a 4- inch -thick layer of clean sand or sand and gravel compacted to a moderately dense state. Over - compaction should be avoided to prevent pumping if the subgrade soils are wet. We recommend that foundation drains be installed along the outside of the thickened edge sections of the foundation system. These drains, together with the drains for the retaining wall sections of the buildings, should be connected to tight drain lines along the east property lines so that flow can be conducted off -site for disposal in a means which will not adversely affect the stability either of this site or the hillside to the east. Settlement of the foundation system designed and installed as recommended above is expected to be relatively small, probably on the order of 1/2 to 3/4 of an inch. Some differential settlement may occur across units because of the differences of relief of overburden pressure resulting from the varying depths of excavation to establish lowest floor grade levels. INSTRUMENTATION AND MONITORING The purpose of the instrumentation program and long -term monitoring at the site is to establish base line data for the performance of the horizontal drain system and, hence, to set up an early warning system if the water levels in the slope start to rise. The instrumentation program which we envision as being appropriate includes piezometers located in areas where they will not be damaged by site grading and construction activities, a network of inclinometers to monitor any hillside movement, survey stakes on slopes which are regraded or which have cuts made at the toe of the slope, and benchmarks established on building foundations as they are con- structed. We recommend installation of at least 6 additional inclinometers, 4 along the easterly boundary of the project site and 2 along the upper portion of the site, one to the north and one to the south of Inclinometer F. These inclinometers will be installed to function as piezometers as well. 28 GeoEngineers Incorporated The piezometers and inclinometers should be installed at least two months prior to, and preferably as soon as possible, to start obtaining baseline data. The number of additional piezometers installed may vary, depending on how many of the existing ones can be saved. It appears probable that 4 or 5 of the existing piezometers will be lost (D, G, H, J, and K). We recommend installation of 6 to 10 shallow piezometers (i.e., to depths of approximately 20 to 25 feet each) to monitor water levels in the upper soil strata and 3 or 4 additional deep piezometers to supplement the piezometric data developed from the inclinometers. The shallow piezometers will monitor the effectiveness of the westerly interceptor drain and other site drainage facilities. In addition to the long -term instrumentation, slope monitoring stakes should be installed in areas where grading involves cuts into the near - surface soils. These should consist of one or more rows of stakes on 20- to 40 -foot centers from which elevation and alignment records can be maintained to determine whether or not any movements occur in the surficial soils. If any movements are detected, remedial measures will be able to be undertaken promptly. As building foundations are placed, permanent reference points should be established at least on the four corners of each building and the elevations recorded. Future elevation readings of these points will then provide a basis for determining any elevation changes which may occur due to foundation settlements or hillside movements. If hillside movements should occur, they would also be reflected in the inclinometer readings. We recommend that the monitoring program initially require that inclino- meters and piezometers be monitored monthly during construction, bi- monthly between construction seasons and twice a year, in February and August, after completion of the project. More frequent monitoring may be required, depending on the weather. Slope monitoring stakes should be surveyed on an every- other -day basis while grading activities are underway in the immediate area and monthly during periods of construction until project completion. It is anticipated that slope stake systems will be lost in final landscaping. 29 GeoEngineers Incorporated Benchmarks on building foundations should be initialized as soon as they are set and read once when each building unit is about 50 percent complete, once upon completion, and annually thereafter. A detailed action plan should be prepared so that it can be promptly implemented in the event of significant changes in water levels or indications of slope movement. The plan should include trigger levels for the inclinometers and piezometers, and specific actions by responsible parties should be established. We recommend that an overall rise in water level of ten (10) feet in the lower aquifer (Unit C), as measured by the on -site piezometers, be taken as a "trigger" level for remedial action. Other trigger levels related to the WSDOT drain systems should be established once they have been cleaned out and are working properly. Trigger levels for the inclinometers should be based on an increase in displacement of more than 0.2 inches per year. The action plan should consist of the following: 1. Notifying our firm immediately. 2. Analysis of the data by our firm to establish the probable cause of the changed conditions at the site. 3. Developing recommendations by our firm for obtaining additional information if necessary and to implement the necessary remedial measures. These recommendations may include: o Obtaining additional information such as surveying the settlement hubs at the site. o Increasing the monitoring frequency. o Maintenance or restoration of the on -site drainage or WSDOT drain systems. o Installation of new horizontal drains on or off site (WSDOT right -of -way). o Pumping the vertical wells in the WSDOT system. o Implementing localized slope stabilization measures. It should be kept in mind that modifications to the number, locations, and, possibly, types of instrumentation as well as modification in the frequency of monitoring may be appropriate as project construction progresses. 30 GeoEngineers Incorporated For this reason, it is im•erative that GeoEngineers have a continuin arti- ration on the project to coordinate installation of the instrumentation, to recommend changed locations or additional points, to monitor the instrumen- tation, and to interpret the data and advise on the performance of the hillside and recommend what, if any, remedial measures may be appropriate. USE OF THIS REPORT We have prepared this report for use by Dr..H.M. Allenbach and members of the design team. This report should be provided to prospective contractors for their bidding or estimating purposes. Our report, conclusions and interpretations should not be construed as a warranty of the subsurface conditions. As noted previously, we have used data developed by our firm as well as by others at widely spaced locations. If there are changes in the loads, grades, location, configuration or type of construction planned from that which we have been provided, the conclusions and recommendations presented may not be applicable. If design changes are made, we request that we be given the opportunity to review our conclusions and recommendations and to provide a written modification or verification. When the design has been completed, we recommend that the appropriate construction drawings and specifications be reviewed by our firm to see that our recommendations have been interpreted and implemented as intended. The earthwork and site preparation activities are of critical importance to the success of this project. GeoEngineers, Inc. must be involved in the construction monitoring and field to see that our recommendations are properly interpreted and implemented. If we are not involved in the con- struction •hase of the •ro ect, we disclaim an liabilit for the manner in which the construction is accomplished or the results thereafter. The scope of our services does not include services related to construction safety precautions and our recommendations are not intended to direct the contractor's methods, techniques, sequences or procedures, except as specifi- cally described in our report for consideration in design. There are probable variations in subsurface conditions between the explorations and also with time. A contingency for unanticipated conditions should be included in the budget and schedule. The construction monitoring, 31 GeoEngineers Incorporated testing and consultation by our firm will provide the opportunity to confirm that the conditions encountered are consistent with those indicated by the explorations, to provide recommendations for design changes should the conditions revealed during the work differ from those anticipated, and to evaluate whether or not earthwork and foundation installation activities comply with contract plans and specifications. Within the limitations of scope, schedule and budget, our services have been executed in accordance with generally accepted practices in this area at the time the report was prepared. No other warranty, express or implied, should be understood. The conclusions and recommendations in this report should be applied in their entirety. If there are any questions concerning this report or if we can provide additional services, please call. GMD:JKT:da File No. 523 -02 April 25, 1985 Respectfully submitted, GeoEngineers, JI(nc�. ordbn M. Denby Se • Engineer 32 . Tuttle incipal Y Y. _Tu / � 14 cj 1 /AT Z� FSS /ONAi. , GeoEnglneers Incorporated FIGURE 1 SLADE WAY ® DM/-C PARKING PROPOSED INTERCEPTOR TRENCH PROPOSED FRENCH DRAIN \ .1 r AI* DM -14 b �, 444 y 41‘N.+ Fl PARKING 13 DM= 14 r 15 kLlERLNCL: DRAWING LNTIII FD "VALLEY VIEW ESTATES" BY WILSEY F. HAM INC, DATED 5/3/82 N )J NF_aVE 53RO 1 12" DIAMETER DUCTILE IRON SEWER LINE NOTE: PROPOSED INTERCEPTOR TRENCH TO BE LOCATED IN THE FIELD. TRENCH TO BE ALIGNED ALONG CONTOUR AND DRAIN FROM NORTH TO SOUTH. PROPOSED FRENCH DRAIN TO BE LOCATED IN FIELD IN EXISTING DRAINAGE GULLY. 40-D EXPLANATION: BORING LOCATION AND LETTER DESIGNATION DM -1 DAMES E MOORE INVESTIGATION 1961 0 80 1611 SCALE IN FEET GeoEngineers Inc. SITE PLAN FIGURE 3 o z 1. DH•4A6 0.110' Reference: Drawing entitled "Plan of Slide Area with Reconnaissance Data and Proposed Drainage" by Shannon & Wilson, dated June, 1964. Legend: „i.k..) „, Marsh Areas with Surface Seepage 00 Seepage Zones Horizontal Drains Installed by Others 0.4 gpa Flow Measured May 12, 1964 Subdrains to be Installed Under Existing Contract ®. Slope Indicator Installed by Shannon & Wilson, Inc. in June, 1964 e Drill Hole Made by Shannon & Wilson in May –June, 1964 Q Observation Well Installed by the State ® Slope Indicator Installed by the State e Boring Made by Dames & Moore, April, 1961 0 50 i00 150 1 1 I l Scale In Feet GeoEngineers Inc. EXISTING ON SITE HORIZONTAL DRAIN LAYOJT — •• FIGURE 4 A 240— 200- W LL Z Z 160- 0 w J W 120—' 30— PROPERTY LINE 0 z ce 0 m O LL z_ U' Z O C Arl-WA m 0- l9 Z 0. i���, $H. Nu. ■ ,....- PROPERTY LINE ESTIMATED PERC HED WATER TABLE WATER TABLE IN UNIT C • UNIT C UNIT A GRAY SILTY SAND AND SANDY .SILT (COLLUVIUM AND SLOPE DEBRIS) UNIT B GRAY SILT WITH INTERBEDDED WET SILTY SAND TO SAND LAYERS; SLICKENSIDES TOWARDS BASE OF UNIT. UNIT C GRAY SAND AND GRAVEL INTERBEDDED WITH SILT LAYERS; WET. A 240 —200 160 120 80 ELEVATION IN FEET HORIZONTAL SCALE: I" = 40' DATUM: CITY OF TUKWILA GeoEngineers Inc. CROSS SECTION A -A FIGURE 5 WELL GRADED SAND OR CLEAN GRAVEL BACKFILL NON -WOVEN FILTER FABRIC MINIMUM WIDTH =2' 6" PERFORATED PIPE A MINIMUM DEPTH =7' GeoEngineers Inc. 1 SCHEMATIC OF PROPOSED INTERCEPTOR DITCH APPENDIX A FIELD EXPLORATIONS AND LABORATORY TESTING FIELD EXPLORATIONS Subsurface soil and ground water conditions at the site were explored by drilling 8 borings at the locations shown on the Site Plan, Figure 1. The borings were generally terminated in the "waterbearing sand and gravel layer. Total lineal footage was 572 feet. The borings . were drilled using a truck - mounted, 4 -inch inside diameter, hollow -stem auger drill rig. Observation wells consisting of 1/2 -inch PVC pipe with a slotted tip were installed in all borings, except Boring F, after drilling was completed. A double installation was used in Boring J where a well tip was installed at the bottom of the hole and at the contact with the silt at 20 feet depth. A slope inclinometer casing was installed in boring F in order to permit measurement of any future movements in the slope. A geotechnical engineer from our staff was present during the explora- tions. Our representative assisted in locating the borings, obtained repre- sentative soil samples, examined and classified the 'soils encountered, observed ground water conditions and maintained a detailed log of each exploration. The soils were classified in accordance with the Unified Soil Classification System which is described on Figure A -1. The logs of the explorations are presented on Figures A -2 through A -17. Relatively undisturbed soil samples were obtained from the borings using a heavy -duty sampler with 2 -1/2 -inch brass liner rings. The sampler was driven using a 250 -pound hammer falling a distance of 30 inches. The driving resistance for one foot of penetration is noted on the logs adjacent to the sample notations. All samples were sealed in containers to limit moisture loss, labeled and taken to our laboratory for further examination and testing. LABORATORY TESTING Selected samples were tested to determine the field moisture and density and strength characteristics. The moisture - density data are presented on the logs of the explorations next.to the appropriate sample notations on Figures A -2 through A -18. A - 1 GeoEngineers Incorporated BORING LOG AND SAMPLE DATA KEY DRIVEN SAMPLES BLOWS REQUIRED TO DRIVE SAMPLER ONE FOOT OR MOISTURE CONTENT 28 11.2% 111 II DRY DENSITY ® IN PCF ❑ INDICATED PENETRATION USING POUND HAMMER FALLING INCHES "POE INDICATES SAMPLER PUSHED WITH WEIGHT OF HAMMER INDICATES LOCATION OF UNDISTURBED SAMPLE INDICATES LOCATION OF DISTURBED SAMPLE INDICATES LOCATION OF SAMPLING ATTEMPT WITH NO RECOVERY GRAPHIC LOG OTHER TYPES OF SAMPLES SM LETTER SYMBOL SOIL TYPE DISTINCT CONTACT BETWEEN SOIL STRATA GRADUAL CHANGE BETWEEN SOIL STRATA INDICATES LOCATION OF THIN WALL, PITCHER, OR OTHER TYPES OF SAMPLES (SEE TEXT) % / BOTTOM OF BORING UNIFIED SOIL CLASSIFICATION SYSTEM MAJOR DIVISIONS LETTER SYMBOL DESCRIPTIONS COARSE SOILS Po a TON sox OF MATERIAL I5 LAB= TWO NO. 200 SIEVE SIZE GRAVEL AND GRAVELLY MARE THAN sox OF COARSE - TIM( Kul= I NO. 4 SIEVE CLEAN GRAVELS (LITTLE DR ND FINES) GW ED GRIELS.OR NOVE SAN WELL-GRADED. V FINES G P POORLY-GRADED GRAVELS. GRAVEL- SAND MIXTURES. LITTLE DR Po FOES GRAVELS WITH FINES (APPRECIABLE NOWT OF FINES) GM SILTY GRAVELS, GRAVEL-SAND-SILT MIXTURES GC CLAYEY GRAVELS, GRAVEL- SAND -SILT MIXTURES SAND AND SANDY SOILS PORE THAN SOX CF COARSE FRAC- iuyi CLEAN SANDS oR NO FIS) (LITTLE NE SW YELL GRADED NOS. GRAVELLY SANDS. LITTLE OR NO FINES SP POORLY - GRADED SANDS, GRAVELLY SANDS. LITTLE OR NO FINES SANDS WITH FINES (APPRECIABLE AMO(XQT OF FINES) SM SC SILTY SANDS, SAND-SILT MIXTURES CLAYEY SANDS. SAM-CLAY MIXTURES ,T(ID°+sel FINE GRAINED SOILS MorE THAN pox OF MATERIAL IS SILTS AND CLAYS LIQUID LIMIT LESS THAN 50 ML INORGANIC SILTS. AND VERY FINE SANDS. s..NOSFORLRCCLASYEY SILLTTSCwITHYSLIGHT PLASTICITY CL INORGANIC CLAYS OF La TO MEDIUM PLASTICITY, GRAVELLY CLAYS. SANDY CLAYS. SILTY CLAYS. LEAN CLAYS OL ORGANIC SILTS AND ORGANIC SILTY CLAYS OF LOW PLASTICITY SILTS AND CLAYS LIQUID LIMIT GREATER THAN 50 MH INORGANIC SILTS. MICACEOUS DR DIATO- ND WOOS FINE SA OR SILTY SOILS CH INORGANIC curs OF NIGH PLASTICITY FAT CLAYS 00 SIC E SIZE OH ORGANIC CLAYS OF MEDI(M TO NIGH PLASTICITY. ORGANIC SILTS HIGHLY ORGANIC SOILS PT PEAT, HUMUS, SWNO SOILS WITH NIGH ORGANIC CONTENTS NOTE, DAL SYMBOLS INDICATE BORDERLINE 5O1L CLASSIFICATION Geo Engineers Inc. 9 UNIFIED SOIL CLASSIFICATION SYSTEM AND KEY TO SAMPLE DATA FIGURE A -2 0 BORING C ELEVATION: 237.1 FEET GRAPHIC TEST DATA LOG DATUM: CITY OF TUKWILA DESCRIPTION 5 — 20 — 2 5 '" 30 35— 40 — 5 23.8% 99.111 9 31.9% 91.511 29 31.2% 91.7 11 28.3% 94.2ii 32 24.5% 100.91 53 24.6% 100.5 54 6.990 98.31 53 9.6Q 122.8 11 S ML 7 ML SP BROWN SILTY SAND WITH GRAVEL (STIFF., MOIST) CRAY SANDY SILT WITH RUST STAINS (STIFF, MOIST) GRAY SILT WITH WET FINE SANDY SILT INTERBEDDED (STIFF, MOIST) SLICKENSIDES SLICKENSIDES FINE SANDY SILT LENSES SLICKENS1DES GRAY FINE TO MEDIUM SAND (MEDIUM DENSE TO TO DENSE, MOIST) HIT GRAVEL AT 38 FEET FOR 2 FEET, THEN SANDY, THEN BACK INTO GRAVEL *SEE KEY FOR EXPLANATION OF SYMBOLS GeoEngineers Inc. LOG OF EXPLORATION FIGURE A -3 40 BORING C (CONTINUED) GRAPHIC TEST DATA LOG DESCRIPTION 45- H 4. 50 z H H w 55 60 65 70" 75 51 6"" 14.30 116.111 93 34.90 82.711 50 4" 26.0% 99.011 50 511 26.6% 98.711 50 52 16.1% 119.211 89 6" 4.0 159.8 11 7.10 60 6" ML SM SM ML SM ML GM GRAY GRAVELLY SANDY SILT TO SILTY SAND WITH WET FINE TO MEDIUM SAND LENSES (STIFF TO DENSE, MOIST) GRAY FINE TO MEDIUM SAND WITH SOME SILT, ORGANIC FRAGMENTS AND MICA (DENSE, MOIST TO WET) SHOE CONTAINED WOOD GRAY FINE SANDY SILT (STIFF, MOIST -TO WET) GRAY GRAVELLY SILT WITH FINE TO MEDIUM SAND LENSES AND OCCASIONAL ORGANIC FRAGMENTS (STIFF TO VERY STIFF, ;101ST) GRAVEL AT 64 FEET BORING COMPLETED AT 731 FEET ON 10/20/83 PIEZOMETER INSTALLED AT 732 FEET ON 10/20/83 GROUND WATER LEVEL AT 64 FEET DURING DRILLING *SEE KEY FOR EXPLANATION OF SYMBOLS GeoEngineers Inc. LOG OF EXPLORATION FIGURE A -4 DEPTH IN FEET 0 5 10 BORING D ELEVATION: 178.8 FEET *GRAPHIC *TEST DATA LOG DESCRIPTION 15- 20- 25- 30- 35- 40- 9 26.6% 91.111 14 30.9% 88.811 36 29.6% 93.111 19 23.5% 100.911 32 18.8% 110.611 32 19.7% 110.911 50 511 9.6% 50 2" 6.4% 142.4® ML ML ML SM GP BROWN AND GRAY SILT WITH ORGANIC FRAGMENTS AND ROOTS (STIFF, MOIST TO WET) (FILL ?) GRAY SILT WITH SOME RUST STAINS (STIFF, MOIST) LAMINATIONS DIPPING AT 20 °, OCCASIONAL CALCIUM CARBONATE CONCRETION GRAY SILT WITH POCKETS OF GRAY FINE SAND (STIFF, MOIST) OCCASIONAL GRAVEL WITH FINE SANDY SILT LENSES SLICKENSIDES GRAY SANDY GRAVEL (DENSE, WET) 1 *SEE KEY FOR EXPLANATION OF SY!+ROLS GeoEngineers Inc. LOG OF EXPLORATION FIGURE A -5 40 BORING D (CONTINUED) *GRAPHIC *TEST DATA LOG DESCRIPTION 45 - w 50- z H a ca 55 60 78 6" 7.3% 139.25D 50 3 " 11.5% 50 4" 10.6% 130.8 19.7% 100 T 2 GP GP GRAY SANDY GRAVEL WITH SOME SILT (DENSE, WET) GM GM GRAY SILTY SANDY GRAVEL (DENSE, WET) 7 FEET OF HEAVE AT 571 FEET BORING COMPLETED AT 581 FEET ON 10/19/83 PIEZOMETER INSTALLED AT 581 FEET ON 10/19/83 *SEE KEY FOR EXPLANATION OF SYM6OLS GeoEngineers Inc. 1 LOG OF EXPLORATION FIGURE A -6 DEPTH IN FEET 0 5 BORING . F ELEVATION: 237.0 FEET *GRAPHIC *TEST DATA LOG DESCRIPTION 10- 15- 20- 25- 30- 35- 40- SM BROWN- BLACK -GRAY SILTY SAND WITH ORGANICS (MEDIUM DENSE, MOIST TO WET) (FILL) 5 43.5% 70.911 SM 7 35.0% 86.211 6 ML 27.4% 96.111 14 27.0% 97.911 12 30.3% 93.811 35 30.6% 92.211 51 30.1% 92.511 65 24.3% 101.911 ML ML ML GRAY SAND WITH MICA (MEDIUM DENSE, MOIST TO WET) GRAY FINE SANDY SILT (SOFT, WET) GRAY SILT WITH A TRACE OF CLAY WITH SLICKENSIDES AND SOME WET FINE SANDY SILT LAYERS (MEDIUM STIFF, MOIST) GRAY SILT AND FINE SANDY SILT LENSES AND SLICKENSIDES (STIFF, DAMP) SLICKENSIDES GRAY FINE SANDY SILT WITH SLICKENSIDES (STIFF, DAMP) *SEE KEY FOR EXPLANATION OF SYIABOLS GeoEngineers Inc. LOG OF EXPLORATION FIGURE A -7 40 45 BORING F (CONTINUED) *GRAPHIC *TEST DATA LOG .DESCRIPTION w w 50- z 55- 60- 6 5 - 76 26.5% 97.311 34 20.6% 109.511 50 5 13.5% 122.611 50 2" 9.1% 117.611 50 1T z ML SOME FINE SANDY SILT LENSES ML GRAY SILT INTERBEDDED WITH FINE TO MEDIUM SAND SP (STIFF TO DENSE, MOIST TO WET) INCREASING GRAVEL CONTENT WITH DEPTH GM GRAY SANDY SILTY GRAVEL TO SANDY GRAVELLY SILT ML (DENSE TO VERY DENSE, MOIST TO WET) GM GRAY SANDY SILTY GRAVEL (VERY DENSE, MOIST TO WET) BORING COMPLETED AT 63 FEET 1 INCH ON 10/21/83 GROUND WATER LEVELS MEASURED AT 10.5 AND 53 FEET DURING DRILLING INCLINOMETER CASING INSTALLED AT DEPTH OF 63 FEET 1 INCH ON 10/21/83 *SEE KEY FOR EXPLANATION OF SYMBOLS GeoEngineers Inc. LOG OF .EXPLORATION FIGURE A -8 0 5 BORING G ELEVATION: 179.2 FEET *GRAPHIC *TEST DATA LOG DESCRIPTION w 10- z a 15- 20- 25- 30- 35- 40 20 11.2% 105.011 SM SM BROWN GRAVELLY SILTY SAND WITH SOME COBBLES (MEDIUM DENSE TO DENSE, MOIST) BROWN AND GRAY RED - STAINED GRAVELLY SILTY SAND (MEDIUM DENSE, MOIST) ML GRAY SILT WITH FINE SANDY SILT LENSES 20 (STIFF, MOIST) 25.9% 98.711 15 32.0% 90.311 16 25.7% 99.811 8 35.0% 86.511 18 32.3% 90.811 31 28.7% 92.711 57 27.7% 95.911 7- FINE SANDY SILT LENSES (MOIST TO WET) SLICKENSIDES DIPPING AT 45° FINE SAND LENSES GRADES TO VERY STIFF AND DAMP SLICKENSIDES SLICKENSIDES WITH FINE SANDY SILT LENSES -SEE KEY FOR EXPLANATION OF SYMBOLS GeoEngineers Inc. 1 LOG OF EXPLORATION 40 *GRAPHIC *TEST DATA LOG BORING G (CONTINUED) DESCRIPTION FIGURE A -9 45 - 60 - 65 - 70 - 75 - 80 32 25.1% 99.811 42 25.2% 100.31 21 24.8% 101.111 63 6" 24.0% 101.211 86 6" 12.4% 125.3Eg 50 1" 13.7% 121.9® 70 6" 26.3% 99.411 50 25.3% 96.5 ML ML SP SM GM SP HIT GRAVEL AT 45 FEET GRAY SILT WITH FINE SANDY SILT AND FINE TO MEDIUM SAND LENSES (STIFF, MOIST) SLICKENSIDE GRAY FINE TO MEDIUM SAND WITH GRAY SILT INTERBEDDED (MEDIUM DENSE, WET) INCREASING GRAVEL CONTENT GRAY SILTY SANDY GRAVEL (DENSE, MOIST TO WET) 2 FEET HEAVE AT 67.5 FEET GRAY FINE TO MEDIUM SAND WITH SOME GRAVEL AND OCCASIONAL GRAY SILT LAYER (DENSE, WET) BORING COMPLETED AT 78 FEET ON 10/18/83 GROUND WATER LEVEL AT 491 FEET DURING DRILLING PIEZOMETER INSTALLED AT 78; FEET *SEE KEY F(1R EXPLANATION OF SYMBOLS GeoEngineers Inc. 1 LOG, OF EXPLORATION FIGURE A -10 DEPTH IN FEET BORING L ELEVATION: 207.5 FEET *GRAPHIC *TEST DATA LOG DESCRIPTION 10- 15- 20" 25- 30- 35- 40- 18 9.8% 122.511 6 35.4% 84.911 6 33.4% 89.111 8 26.1% 98.011 22 30.7% 92.211 34 29.9% 93.411 51 27.4% 97.011 43 27.6% 96.411 7 SM BROWN GRAVELLY SILTY SAND (MEDIUM DENSE, MOIST) ML GRAY SILT WITH REDDISH BROWN STAINS AND FINE SAND INTERBEDDED (SOFT, MOIST) J GRADES TO MEDIUM STIFF FRACTURES GRADES TO STIFF 1/8 INCH SAND LENS AT 282 FEET GRADES TO VERY STIFF, DAMP SLICKENSIDE AT 372 FEET *SEE KEY FOR EXPLANATION OF SYMBOLS GeoEngineers Inc. LOG OF EXPLORATION FIGURE A -11 40 *GRAPHIC *TEST DATA LOG BORING L (CONTINUED) DESCRIPTION 45 - H w 50- z a 55- 60- 65— 73 22.3% 104.41 86 25.8% 98.41 32 23.5% 104.41 52 6" 13.5% 125.911 ML SM ML SP GM GRAY INTERBEDDED SILT AND FINE SAND (VERY STIFF, MOIST) FRACTURES AND SLICKENSIDES GRAY FINE SAND (LOOSE TO MEDIUM DENSE, WET) GRAY SANDY GRAVEL WITH A TRACE TO SOME SILT HEAVE AT 611 FEET BORING COMPLETED AT 63 FEET ON 10/14/83 GROUND WATER LEVEL ESTIMATED AT 49 FEET DURING DRILLING PIEZOMETER INSTALLED AT A DEPTH OF 63 FEET ON 10/14/83 GeoEngineers Inc. *SEE KEY FOR EXPLANATION OF SYMBOLS LOG OF EXPLORATION FIGURE A -12 DEPTH IN FEET 0 BORING H ELEVATION: 229.5 FEET *GRAPHIC *TEST DATA LOG DESCRIPTION 5- 10- 15- 20- 25- 30- 35- 6 SP SP BROWN SILTY FINE SAND WITH GRAVEL (MEDIUM DENSE, MOIST) (FILL) TAN TO BROWN FINE SAND WITH RUST STAINS (LOOSE, MOIST) 21 30.5% 90.811 ML GRAY SILT. WITH SAND LENSES (STIFF, MOIST) 24 30.2% 92.411 22 28.6% 95.21 31 30.9% 92.21 24 25.6% 100.411 29 26.2% 99.71 21 28.8% 95.411 /WITH A TRACE OF CLAY *SEE KEY FOR EXPLANATION OF SYMBOLS GeoEngineers Inc. LOG OF EXPLORATION FIGURE A -13 DEPTH IN FEET 40 *GRAPHIC *TEST DATA LOG BORING H (CONTINUED) DESCRIPTION 4S- 50- 55- 60- 65- 25 33.1% 90.111 34 29.9% 93.511 46 28.0% 95.911 66 28.2% 96.1 1 22.6% 102.811 WITH SAND INTERBEDDED, SLICKENSIDES, AND VERTICAL SAND /SILT CONTACT IN SAMPLE GRAY SILT INTERBEDDED WITH SAND VERTICALLY GRAVEL OBSERVED BY DRILLER GRAY SILT INTERBEDDED WITH SAND LENSE AT 70 DEGREE DIP GRAVEL IN BARREL ABOVE SAMPLE BORING COMPLETED AT 621 FEET ON 10/13/82 GROUND WATER OBSERVED AT 55 FEET DURING DRILLING PIEZOMETER INSTALLED AT 621 FEET -SEE KEY FOR EXPLANATION OF SYMBOLS GeoEngineers Inc. 1 LOG OF EXPLORATION FlqURE A-14 BORING J ELEVAf{AN: 195^4 FEET *GRAPHIC *1TST DATA 1,00 DESCRIpTTO 20- 25 -~ 50 7 30.2% 90.411 5 28"2% 95:811 17 32.2% 1 18 31'6% 91.011 18 31^8% 88.011 24 2.4% 90'011 22 2.3% 90'011 , .' SM 8kOWN GRAVELLY SILTY SAND WITH WOOD FRAGMENTS (MEDIUM DENSE' MOIST) ML GRAY SILT INTERBEDDED WITH SAND LENSES (SOFT, MOIST) GRADES TO STIFF WITH SLICKENSIDES AND FRACTURING FRACTURES 5LlCKEN5lDE5 OCCASIONAL BROWN STAINS SLlCKENSIDES *SEE KEY FOR EXPLANATION OF SYMBOLS GeoE ngN neers Inc. LOG OF EXPLORATION. FIGURE A -1 5 40 *GRAPHIC *TEST DATA LOG BORING J (CONTINUED) DESCRIPTION 25 30.9% 92.611 45 23 32.0% 90.111 L*. 50 - z x H 29 2 A 33.7% 89.011 55 - 23 28.7% 93.711 60 - 96 23.6% 100.911 65 - 47 25.9% 89.811 70 - 106 18.3% 106.111 75- 59 6" 18.7% 110.211 80 -- ML ML GP WITH SLICKENSIDES AND BROWN STAINS LARGE SLICKENSIDE GRADES TO VERY STIFF FEW SLICKENSIDES WET SAND LENSES AND RUST STAINS GRAY SILT WITH SOME GRAVEL, SLICKENSIDES, RUST STAINS, AND SAND LENSES (VERY STIFF, DAMP) HIT GRAVEL BETWEEN 77 TO 80 FEET *SEE KEY FOR EXPLANATION OF SYNROLS GeoEngineers Inc. 1 LOG OF EXPLORATION FIGURE A -16 80 85 DEPTH IN FEET *GRAPHIC *TEST DATA LOG BORING J (CONTINUED) DESCRIPTION 111Gr SP GRAY FINE TO MEDIUM SAND (MEDIUM DENSE, WET) HEAVE AT 822 FEET BORING COMPLETED AT 84 FEET ON 10/15/83 GROUND WATER LEVEL ESTIMATED AT 492 DURING DRILLING .PIEZOMETER INSTALLED AT A DEPTH OF 822 FEET AND 20 FEET *SEE KEY FOR EXPLANATION OF SYMBOLS GeoEngineers Inc. 1 LOG OF EXPLORATION FIGURE A -1 7 0 5 W 10 z H BORING K ELEVATION: 175.0 FEET *GRAPHIC *TEST DATA LOG DESCRIPTION 13 21.7% 99.611 9 26.3% 97.011 H 8 w 34.1% 87.711 15- 10 28.3% 97.011 20- 5 35.5% 87.311 2 5 "' 20 29.8% 92.411 30- 20 26.4% 93.511 35 - 36 26.1% 98.211 40 - SM BROWN GRAVELLY SILTY SAND WITH RED AND DARK BROWN STAINS (LOOSE TO MEDIUM DENSE, MOIST) ML GRAY SILT WITH SAND LENSES AND RUST STAINS (STIFF, MOIST) MOTTLED APPEARANCE GRADES TO SOFT AND WET SLICKENSIDES GRADES TO STIFF AND MOIST TO WET SLICKENSIDES AND BROWN STAINS SLICKENSIDES AND BLOCKY FRACTURES *SEE KEY FOR EXPLANATION OF SYMBOLS GeoEngineers Inc. 1 LOG OF EXPLORATION FIGURE A -18 40 BORING K (CONTINUED) *GRAPHIC *TEST DATA LOG DESCRIPTION 45 - F w 50- z 32 27.7% 95.911 54 27.9% 96.711 H 31 A 27.1% 96.41 55- 60- 65- 70- • 75" 80- 58 30.1% 93.011 82 25.3% 98.411 76 27.0% 98.011 50 4" 24.5% 101.311 65 20.2% 110.011 1 ML MANY SLICKENSIDES .VERTICAL COLOR CONTACT IN SILT SLICKENSIDES DISTORTIONS IN SAND LENSE SLICKENSIDES GRADES TO VERY STIFF MANY SLICKENSIDES SLICKENSIDE TRACE OF SOME VERY FINE SANDY WET VERY FINE SANDY SILT LENSES ML GRAY FINE SANDY SILT (STIFF, WET) GP /BROWN SILTY SANDY GRAVEL (DENSE, WET) *SEE KEY FOR EXPLANATION OF SYMBOLS GeoEngineers Inc. 1 LOG .OF EXPLORATION FIGURE A -19 80 BORING K (CONTINUED) *GRAPHIC *TEST DATA LOG DESCRIPTION 85- z x w 70 6" 23.0% 104.011 50 4" 25.9% 98.811 GP ML GRAY FINE SANDY SILT (STIFF, WET) BORING COMPLETED AT 88 FEET 9 INCHES ON 10/17/83 GROUND WATER LEVELS MEASURED AT 14 FEET AND 79.5 FEET DURING DRILLING PIEZOMETER INSTALLED IN GRAVEL LAYER AT 88 FEET *SEE KEY FOR EXPLANATION OF SYMBOLS GeoEngineers Inc. LOC OF EXPLORATION APPENDIX B INSTRUMENTATION AND MONITORING PIEZOMETRIC LEVELS A series of water level measurements was made in the piezometers installed by GeoEngineers, Inc.; in Piezometers 1A, 1B, and 1 installed by Shannon & Wilson in 1966; and in the Group 1 vertical wells installed by the Washington State Department of Transportation (WSDOT) during construction of the I -5 /I -405 interchange in the mid- 1960s. The water levels measured in the piezometers and wells since November 1983 are presented in Tables B -1 through B -3. The elevation datum used is the Valvue Sewer District datum. INCLINOMETER DATA The inclinometer in Boring F was initialized on November 1, 1983. Subsequent sets of readings were taken on November 18, 1983 and March 12, 1985. The readings indicate no discernible movements at this time. The data are available for review or copying from our files. B - 1 GeoEngineers Incorporated TABLE B -1 PIEZONETRIC LEVELS - GEOENGINEERS, INC. BORINGS Ground Elevation of Water Table (Feet) Surface Elev. Boring (feet) 11/18/83 11/30/84 3/4/85 3/12/85 C 237.1 196.6 196 197 D 178.8 172.7(1) 172(1)(2).. 123 .123 G 179.2 163.3(1) 103 102 H 229.5 189.1 184.5 183.5 J(top) 195.4 184.1. 184.5 185.5 185.5 J(bottom) 195.4 167.8(1) 114.5 166.5(1) 114.5 K 175.0 129.5 - (3) L 207.5 177.6 177.5 178 NOTES: (1) High water levels possibly due to surface water infiltration. (2) Reading obtained on 12/12/84. (3) Piezometer K plugged at 7 foot depth. B - 2 GeoEngineers Incorporated TABLE B -2 PIEZOMETRIC LEVELS - SHANNON & WILSON PIEZOMETERS Casing Elevation of Water Table Elev. (Feet) Piezometer (feet) 3/4/85 3/12/85 IA 148.5 93.5 93.5 1B 151.5 111.5 111.5 1(1) 165.0 146.5(1) 139 (1) NOTE: (1) Piezometer 1 consists of a slope indicator casing and is obstructed at Elevation 130. B- 3 GeoEngineers Incorporated TABLE B -3 PIEZOMETRIC LEVELS - GROUP 1 WSDOT WELLS Casing Elevation of Water Table (feet) Elev. Well No. (feet) 11/30/84 3/4/85 3/12/85 1 161.4 143.5 144 144 2 162.6 148.5 147 147 3 162.8 152.0 152.5 152.5 4 166.2 - 101 101 5 166.5 103.5 104.5 104.5 6 166.4 - (1) - - 7 163.2 140 140 8 162.1 124 124 9 162.6 109.5 109.5 10 157.5 107.5 107.5 107.5 11 156.8 108 108 108 12 157.3 108.5 108.5 107.5 13 155.0 104 104 14 153.8 111 112 112 15 152.8 113 113 16 147.4 116.5 115.5 17 146.6 116.5 116.5 18 145.4 117.5 116.5 19 136.5 94.5 94.5 20 135.1 118 118 21a - (2) 21b 133.1 117 117 116 22 131.0 dry at 86' dry at 86' dry at 86' 23 131.3 96.5 97.5 24 130.3 97 96.5 NOTES: (1) Well No. 6 plugged at 9 foot depth. (2) Well No. 21a plugged at 10 foot depth. B - 4 GeoEngineers Incorporated • TABLE B-4 GROUP 1 WSDOT VERTICAL WELL /HORIZONTAL DRAIN SYSTEM Well Horizontal Drain Parameters Ground GEI WSDOT Surface Pump Elevation Outlet Well Well No. Elevation Elevation at Well Elevation Grade Length No. Series No. Feet Feet Feet Feet % Feet 1 I 1 159.6 60.1 80.9 80.5 2 213.0 2 2 160.1 61.0 82.6 80.5 1 222.6 3 3 160.5 56.0 81.6 80.5 2 223.1 4 II 1 164.6 54.5 82.1 81.7 2 233.6 5 2 164.3 51.8 82.8 82.8 2 223.4 6 3 164.1 51.6 86.9 82.6 2 223.6 7 III 1 162.3 53.4 83.4 83.3 2 223.7 8 2 161.5 51.3 88.0 83.9 2 212.8 9 3 161.0 52.7 86.5 84.4 1 213.7 10 IV 1 156.7 50.6 84.5 84.9 0 204.9 11 2 155.4 53.0 87.3 85.0 1 203.3 12 3 156.5 51.4 90.1 86.2 2 214.8 13 V 1 153.3 50.2 87.8 87.4 1 183.8 14 2 152.4 54.2 89.7 88.0 1 184.3 15 3 151.2 N/S 90.1 88.4 1 184.7 16 VI 1 145.7 42.5. 90.6 89.8 2 152.8 17 2 144.7 N/S 92.0 90.6 1 153.2 18 3 143.8 62.8 92.4 91.0 1 152.9 19 VII 1 133.5 N/S 93.7 93.0 1 134.8 20 2 132.9 N/S 95.8 94.5 1 135.1 21 3 132.2 N/S 94.6 94.6 0 126.6 22 VIII 1 128.2 N/S 97.1 97.1 0 95.0 23 2 128.9 N/S 97.5 97.5 0 84.8 24 3 128.6 N/S 97.9 97.9 0 85.5 N/S Not shown on WSDOT documents. B - 5 GeoEngineers Incorporated A P P E N D I E C SLOPE STABILITY ANALYSES INTRODUCTION A description of the slope stability analyses for the deep- seated sliding failure mode and the results are presented in this appendix. Methodology: Deep- seated block -type sliding was analyzed with the aid of the computer program STABL, which allows analyses of shear surfaces of general shapes, including sliding blocks. The program is based on Carter's Method. Critical failure surfaces are generated using pseudo random techni- ques. The input parameters include slope topography, piezometric levels in the lower sand aquifer, soil strengths, earthquake acceleration coefficients and building loads on the slope. The initial phase of our analyses included back - calculating soil strengths from conditions existing during sliding in 1961. The back - calculated soil strengths were obtained by changing the input values to achieve a computed factor of safety of about 1.0. These strengths, along with water level and topographic information were used to compute a new factor of safety for conditions existing in March 1985. The effects of water level rise, earthquake loading, and building loads on the factor of safety were then evaluated. Assumptions: Several assumptions were necessary in evaluating deep - seated block sliding stability. Topography representative of conditions existing in 1961 (soon after the major slide of 1960) and those existing at present (1985) were evaluated. Topographic conditions assumed in 1961 were based on Plate 3"of the Dames & Moore report dated June 27, 1961. Topographic conditions existing at present (1985) are based on topographic information provided by Stepan & Associates, Inc. for the section of the slope located between the uphill and downhill property lines. Topography below the downhill property line and above the uphill property line was estimated from Figure 1 in the Shannon & Wilson report dated June 21, 1968. The sections judged most critical of those used in our analyses are shown on Figures C -1 and C -2 for the 1961 and 1985 topographies, respectively. C- 1 GeoEngineers Incorporated The location of the section depicted on Figure C -1 and C -2 is shown on Figure 1. The location of the section used in the 1961 Dames & Moore report differs from that used in our analyses and is located to the southeast of the section we have used. The section shown on Figure C -2 is drawn through the center of a large swale, while the borings drilled both for our studies and by Dames & Moore are located on the flanks of this swale. The differences in topographic conditions shown in 1961 and 1985 indicates that a significant amount of material is absent from the lower portion of the slide area, particularly below the downhill property line. The difference could be attributable to material removal as well as to the different sections used by Dames & Moore and GeoEngineers. Soil conditions depicted in all of the borings used to develop our cross sections vary significantly. This is especially true of Borings DM -1 and D, DM -3 and G, and DM -4 and C. Variations across the swale are also apparent when comparing the logs for Borings DM -1 and DM -3 with D and G, respectively. The presence and variable elevations of sand lenses throughout the thick fine - grained layer (Unit B) probably account for the major part of this variability. They also have a significant influence on the location of the failure surface. The location of failure zones identified from slope indicator measurements in the Dames & Moore borings and zones of slickensided material encountered in Borings C, D, G, L and F were used to estimate the probable location of the slide plane in our analyses. See Figure 1. For both topographic conditions (1961 and 1985), the soil conditions were simplified to a three -layer system. The uppermost layer includes the surficial silty sand and thick fine - grained soil units (Units A and B shown in Figure 1). The second layer (underlying the thick fine - grained soil unit) was assumed as a thin (5- foot - thick) zone of weak material through which the slide plane passes. Material underlying this weak layer was assigned a higher strength and represents dense glacially compacted soils through which the slide plane probably does not pass. The extent of the weak zone was estimated from our borings and the Dames & Moore borings. C - 2 GeoEngineers Incorporated Water levels for the 1961 analysis had to be estimated as artesian conditions existed at the time the borings were drilled by Dames & Moore in 1961. Based on the observations by Dames & Moore personnel of the rate of flow from the borings, the piezometric surface was assumed at 5 feet above the existing ground surface. Water level information from our borings and Shannon & Wilson Piezometers 1, 1A and 1B were used to establish the piezometric surface existing in 1985. The sliding block failure surface was modeled using five constraint areas positioned along the lower boundary of the assumed weak zone. The downhill exit point for the slide was based on the exit point indicated in the 1961 Dames & Moore report. This exit point may have been observed at that time because this portion of the site was cleared as a result of borrow operations. The failure surfaces are shown in Figures C -1 and C -2 for 1961 and 1985, respectively. Selection of Parameters: The analyses using 1961 conditions were performed by varying soil strengths of the upper two soil layers until a factor of safety of approximately 1.0 was obtained. The friction angles for this condition were computed at 25 degrees for the upper material and 15 degrees for the weak zone material. These friction angles are considered to be residual values and the cohesion intercepts were accordingly assumed to be zero. The analyses indicate a zone of critical failure surfaces having nearly equal factors of safety near the uphill property line. See Figure C -1. Results: The failure surface and piezometric conditions evaluated for existing conditions are shown in Figure C -2. The analyses indicate a factor of safety of 1.5 to 1.6 for the section assumed in the analysis. Our analyses of the stability of sections located outside of the swale yield factors of safety approximately the same for existing piezometric conditions. Additional Analyses: We then evaluated the effects of an increase in the water level. Factors of safety of 1.3 and 1.0 were obtained when the piezometric levels were raised 10- and 20 -feet, respectively, above existing levels. C - 3 GeoEngineers Incorporated We also evaluated the effect of the building loads on deep- seated stability by assuming an average areal building load of 200 pounds per square foot extending over the building footprints at two locations on the slope. The factor of safety obtained for this loading condition was nearly identical with that obtained without building loads. Dynamic Analysis: Dynamic stability was evaluated by subjecting the slope to a horizontal acceleration coefficient of 0.15 with the piezometric surface at current levels. We assigned a cohesion value of 500 psf and a friction angle of 15 degrees to the weak zone to represent undrained soil strength. This is considered to be conservative and to be more appropriate for earthquake loading. A factor of safety of 1.13 was obtained for these conditions. While the factor of safety indicated for dynamic loading conditions is relatively low, this value is considered, in general practice, to provide a level of risk comparable to a factor of safety of. 1.5 for static conditions. Strains and, therefore, slope movement developed during earthquake loading will probably be limited. This is normally observed in cohesive soils during earthquake loading and is indicated by the reported localized zones of cracking in the uphill portion of the slide area during the 1965 Seattle earthquake. C - 4 GeoEngineers Incorporated FIGURE C -1 360— 320 — 780 -, 740 — 200— a 160— > 120 — (0,100) (243,162) PROPERTY LINE 1961 Topography ESTIMATED PIEZOMETRIC LEVEL (364,173) i� PROPERTY LINE ZONE OF GENERATED CRITICAL FAILURE SURFACES SLADE WAY (728 252) (786,253) (880,275) 1 = 125 PCF SOIL pl °C = = 20 (880,228) (96,116) _ � (364,133) 80 (0,82) (120,88) (0,64) 40— 5)101NG 010(6 1AILuRt Su,EA(E (526,166) (880,209) (880,204) SOIL OI 7 = 120 PCF C = 0 0 = 15' SOIL 07 ( = 130 PCF C = 0 0 = 35. — 360 — 320 280 — 240 200 z 0 —160 — 120 80 —40 1 1 1 1 1 1 1 1 1 1 I 1 1 1 1 1 1 1 40 80 120 160 200 240 280 320 360 400 440 480 520 560 600 640 680 720 DISTANCE IN FEET 60115: 1) SECTION LINE I5 SECTION A -A' S13OMN IN FIGURE 1. 2) TOPOGRAPMT BASED ON PLATE 3 IN DAMES C MOORE REPORT DATED 6/27/61 AND CORRESPONDS TO CONDITIONS EXIST- ING AITLR SLIDE OF 1960 -61. 3) MA1FR LEVELS ESTIMATED (ROM BORINGS DRILLED BY DAMES C MOOR8 IN 1961. I I 760 800 840 880 0 GeoEngineers Inc. CROSS SECTION FOR STABILITY ANALYSIS • • • • • • • - • - • • • • • • • • FIGURE C -2 360 -- 370- 280 - 240 - L.." 700- 160- > 120 - (0,100) 80 _J0,76) (0,69) (0,64) 40 - 1985 Topography PROPERTY LINE (302,141) ESTIMATED PIEZOMETRIC SURFACE (457,171) (542,200) C5�6, 17� (526,166) (120,93) (242,115) (120,88) l - (526,171) (364,133) SLIDING BLOC[ IAILURE SURFACE ZONE OF GENERATED CRITICAL FAILURE. SURFACES PROPERTY LINE SLADE WAY (728,252). (786,253) (880,275) SOIL U I = 125 PCF C = 0 0 = Z5' r = 120 PCF C = 0 0 = 15' 501L 0 8 = 130 PCF C = 0 0 = 35 I I (880,204) 1 t I I I 1 1 1 1 1 I I I I 1 I 40 80 170 160 200 240 280 320 360 400 440 480 520 560 600 640 680 720 760 800 840 DISTANCE IN FEET NOTES: 1) SECTION LINE 15 SECTION A -A' SHOWN IN FIGURE 1. 2) TOPOGRAPHY BELOW DOWNHILL PROPERTY LINE AND ABOVE UPHILL PROPERTY LINE BASED ON FIGURE 1 IN SHANNON C WILSON REPORT DATED 6/21/68. 3) TOPOGRAPHY BETWEEN PROPERTY LINES BASED ON PRE- LIMINARY TOPOGRAPHIC MAP PROVIDED BY STEPAN C ASSOCIATES, INC., DATED MARCH, 1985. 4) WATER LEVELS RASED ON MEASUREMENTS MADE IN PIEZOMETERS INSTALLED BY GEOENGINLERS AND SHANNON C WILSON, AND IN GROUP 1 VERTICAL DRAINAGE WELLS INSTALLED BY WSDOT. - 360 - 320 280 -240 (880,228) (880,204) 200 z -160 880 z 0 i 120 80 40 GeoEngineers Inc. CROSS SECTION FOR STABILITY ANALYSIS APPENDIX B UTILITIES REPORT VALLEY VIEW ESTATES UTILITY REPORT Prepared By: STEPAN & ASSOCIATES, INC. 930 SOUTH 336TH STREET FEDERAL WAY, WASHINGTON 98003 5 -1 -85 STORMWATER RUNOFF /ABSORPTION EXISTING CONDITIONS The site slopes generally from west to east with a drainage swale bisect- ing the southern portion of the site. Slopes vary from 3% to 50 %. Site vege- tation consists of alder, a few maple and dense blackberry vines. As stated in the surface water portion of the geotechnical report pre- pared by Geo Engineers, permeability is relatively low in Units A and B (ref. Figure 4 in the geotechnical report) and significantly higher in Unit C. The Washington State Department of Transportation has installed a series of large diameter wells and horizontal drains just east of the site to modify and control the water table (Ref. Figure 1 in the geotechnical report). This sys- tem was installed during the construction of Interstate 5. This will be referred to as the WSDOT system in the remainder of this report. Impacts: Existing surface runoff and absorption characteristics would be altered of the proposed development: the installation of drainage systems, removal of vegetation during site preparation, fill and grading, and introduction of impervious surfaces on the site in the form of roads, parking areas, and structures. Off -site features such as the City of Seattle water line should not be effected by the proposed development. Absorption would be reduced, and the volume of runoff would be increased as described below. Mitigating Measures: The proposed stormwater facilities as shown on the attached Site Utility Plan and sub - surface facilities as described in the geotechnical report prepared by GeoEngineers would mitigate the impacts of site development on runoff and absorption characteristics. The engineering drawings for the storm water system will be prepared in accordance with City of Tukwila requirements and are subject to City review and approval. SURFACE WATER MOVEMENT AND QUANTITY Existing Conditions: The site drainage basin is bounded by Slade Way and the extension of 158th Street on the north. The basin area is 7.2 acres and is divided into 2 sub basins the south being 4.4 acres and the north 2.8 acres. Drainage from the site flows directly to the Green River through a series of pipes and open channels which are described below. Surface runoff from the southern portion of the site (4.4 acres) sheet flows to a rip -rap lined ditch which bisects the south side of the site. This ditch flows to a receiving structure on the south side of Klickitat Drive. A 24 -inch pipe runs from the receiving structure to a manhole where the pipe size increases to 30" under Klickitat Drive. This 30 -inch line then runs para- llel to Klickitat and connects to a 48" line which runs parallel to the north- bound lane of Interstate 5. The 48 -inch line then crosses under Interstate 5 and discharges in a lined open channel which is on the west and north side of Southcenter Parkway. The channel flows through a short section of 78 -inch pipe and a section of 108 -inch pipe and then discharges in the Green River. -1- Surface runoff from the north portion of the site (2.8 acres) sheet flows to a lined ditch along the east side of the site. The ditch flows to a receiv- ing structure near the northeast corner of the site. An 18 -inch pipe runs from the structure to a manhole where the pipe size increases to 24 ". This line runs under Interstate 5 and ties into the same 48 -inch line which was described in the preceding paragraph. The flows follow the same route to the Green River as described for the southern portion of the site. The WSDOT system of vertical wells are connected to horizontal drains which also flow to the systems described above. Off -site flow from approximately 12 acres of mostly single- family resi- dences west of Slade Way and south of South 160th Street enters the site south of the intersection to South 160th Street and 53rd Avenue South. Part of this system parallel to 53rd Road South runs above ground, and is leaking (observa- tion 10/17/83), causing some ponding in the immediate area. The system also consists of 12 -inch and 18 -inch underground pipe and runs generally in a north south direction. This pipe connects to the same 24 -inch line described in the paragraph above. From here the runoff travels the same path to the Green River as that previously described. Impacts: Construction of the proposed development would not alter existing drainage basin boundaries. Site development would eliminate existing natural surface flow and infiltration characteristics and introduce an addi- tional buried conduit system. The new drainage collection system would con- tain and direct surface water at higher velocities and in different directions across the site, as shown on the Site Utility Plan; however, stormwater would continue to exit the property at the same points along the southern an eastern boundary. Changes in potential peak flow of storm runoff due to building construc- tion and paving will be controlled by the drainage retention and runoff con- trol system. Surface water would be collected in a subsurface conduit system as shown on the site utility plan, which would direct stormwater drainage at higher velocities and in slightly different directions across the site. The new storm sytem would also collect existing on -site horizontal drains (ref. Figure 3 - GeoEngineers Report and footing and retaining wall drains. The proposed drainage system includes storm drainage retention pipes and control structures which would control and store storm water to limit the runoff rate to a predevelopment rate. Therefore, surface water would exit the site at approximately the same rate as it does under existing conditions. The installation of a storm drain system would provide positive benefits because it would collect and channel surface water, some of which is currently flowing in ill- defined channels, and direct it to a controlled system outflow. The storm drain system and the system of foundation wall drains will also increase the factor of safety against sliding in the upper layers of soil (Ref. page 15 geotechnical report) and provide less impact on the WSDOT System (Ref. page 23). The 7.2 acre drainage basin is divided into 2 sub basins the south being 4.4 acres and the north 2.8 acres. Based on a storm of 10 year recurrence interval, the south basin would require approximately 1,500 cu. ft. of storage capacity, and the north basin would require approximately 1,000 cu. ft. of storage. The size of the controlled outlet from the site would be runoff at a rate that would not exceed existing conditions. -2- Since runoff from the site flows directly to the Green River as detailed in the preceding paragraphs, an alternate to this would be to provide no deten- tion for the site. This is a normal practice on sites which flow directly to a large body of water or river. There would be several benefits from this. The principal benefit would be elimination of a possible source of water leakage from the detention struc- ture. It would also eliminate some of the excavation and disturbance of the hillside on -site. As shown on the attached storm calculation sheet the introduction of impervious surfaces would increase the peak surface runoff from a total of 1.36 cubic feet per second (CFS) to approximately 3.34 CFS during 10 -year storm conditions. This is an increase of 1.98 CFS at the peak. Surface run- off would increase a total of 1.67 CFS to 4.13 CFS during a 25 -year storm. This is an increase of 2.46 CFS at the peak runoff. This is a relatively small increase given the size and capacity of the downstream storm system which is capable of handling 20 CFS or greater. Mitigating Measures: A stormwater system designed in accordance with City of Tukwila requirements and requirements and recommendations detailed in the geotechnical report prepared by Geo Engineers is proposed to be installed. The City of Tukwila must approve stormwater drainage plans prior to issuance of the building permit. The site development sequence and facilities as recommended in the geotechnical report prepared by GeoEngineers would be included on the detailed site grading plan. A temporary storm management system and the erosion control measures as described in the geotechnical report will be employed during construction. Where possible, natural vegetation for silt control will be maintained. Temporary siltation ponds shall be constructed by placing straw bales across swales. All temporary and erosion control measures will be maintained in a satisfactory condition until such time as cleaning and /or construction is completed and permanent drainage facilities are operational. The temporary siltation ponds should not effect the groundwater table. The proponent would have maintenance responsibility for the drainage control facilities during construction, and it is proposed that the owner assumes maintenance responsibility for these on -site facilities after comple- tion of the development. Cleaning, flushing and regular maintenance of the WSDOT drain systems described in the geotechnical report is essential. A portion of the existing storm system would be abandoned (See Appendix - Letter from Department of Transportation) and replaced by a new storm line to handle off -site runoff as shown on the site utility plan. The existing storm line that is above ground and leaking would be repaired. Surface Water Quality Existing Conditions: There is no known water quality data for surface runoff from the site. -3- Impacts: The introduction of impervious surfaces over a portion of the proposed development would reduce the area of exposed soils. Therefore, reduced quantities of sediment, nutrients, and organic material contained in the soil would be expected to leave the site in surface runoff. However, in place of these would be contaminants more typical of residential developments: petroleum residues, traces of heavy metals, and sediments washed from roads and driveways. The increased quantity of impervious surfaces would increase the volume of stormwater runoff from the site. Catch basins and oil /water separators proposed within the on -site drainage collection system would func- tion to separate sediments and petroleum residues from stormwater to a certain extent. On -site drainage detention and the outlet control structure would further allow for separation of these pollutants from storm water before release from the site. Use of pesticides, herbicides, and fertilizers (if any) on yards and on landscaping in common areas may occasionally contribute slight quantities of contaminants to stormwater that would not be removed by the proposed pollution separation devices. Also, the partial coverage of soils with asphalt paving and structures may result in slight elevation of temperature of runoff from these surfaces. Perhaps the greatest significant potential for adverse impact on surface water quality would be during temporary construction periods. Clearing and grading would expose soils on the site to potential erosion by rainfall. Mitigating Measures: The proponent would have maintenance responsibility for the on -site drainage control facilities. Cleaning, flushing and regular maintenace of the existng WSDOT systems as described in the geotechnical report is essential. Catch basins and oil /water separators should be cleaned frequently and properly maintained to assure maximum attainable pollution separation. SANITARY SEWER SYSTEM Existing Condition: The site would be served by Val Vue Sewer District. There is an existing 12 -inch cast iron sewage main which runs through the site as shown on the utility site plan. The line connects to Metro at the Hat Highlands connection. Sewage from the site would be treated at the Renton Sewage Treatment Plant and would be transmitted to the plant via the freeway interceptor, Val Vue outfall and Tukwila interceptor. The proposed project is within Metro's Renton treatment plant service area. Metro has prepared a facilities plan for the Renton system with a grant from DOE and EPA, in part because the Renton treatment plant has reached its "design" capacity and continued development is occurring within the service area. A final plan for the Renton service area was adopted by the Metro Council in November, 1981 and contains a recommended program for upgrading the Renton system so that water quality and health will continue to be protectect- ed. The plan was amended on April 5, 1984 to revise the alignment for the effluent transfer system pipeline. These improvements will be on line in early 1987. Impact: The on -site sewage collection system would be designed by the proponent's engineer and would be installed as shown on the site utility plan. Six- and eight -inch lines would collect sewage throughout the project and con- nect into the existing Val Vue sewer line as shown. A field survey of this area has recently been completed which indicates the existing sanitary sewer would be relocated so that it will not be under the proposed buildings. This is indicated on the site utilty plan. As per the attached letter from Val Vue Sewer District the relocation construction of this line can occur without any disruption of service in the existing line. The development will result in increased sewage flows. As stated above, the Renton Treatment Plant is currently treating more than design capacity but temporary measures are being taken which will accommodate flows. The plant will be upgraded by early 1987 if present plans are implemented. Mitigating Measures: If water use was reduced by residents implementing water - saving measures in their homes, the volume of sewage that would be discharged from the project area would also be reduced. SOLID WASTE Existing Conditions: The business and residences in the surrounding vicinity are currently served by Sea -Tac Disposal. Dumpsters and compactors can be rented from them. The solid waste is taken to the King County Transfer Station. Impacts: The proposed development will increase demand for solid waste collection which can adequately be provided by Sea -Tac Disposal. Mitigating Measures: None -5- WATER SYSTEM Existing Conditions: The project is located in Water District No. 75 service area and would be served from the District's supply and distribution system (ref. letters to and from Water District No. 75, attached). The District is supplied from the large Cedar River Pipeline which runs adjacent to the site. The District anticipates that this source will be able to meet long -range demands for water in this area. (Conversation with Duane Huskey on 3/26/85). The District has a 6 -inch main that extends to the intersection of South 160th Street and 53rd Avenue South. There is also an 8 -inch main that extends east on South 166th Street and terminates approximately 200 feet west of the intersection with 54th Avenue South. Static pressure in this area is 125 psi. Impacts: The District's water distribution would be extended from the 6 -inch main in South 160th Street with a new 8" main on Slade Way. This would be as called for in the District's Comprehensive Plan. Connections from this main would supply the proposed development with water. Fire hydrants will be spaced as required to provide adequate fire protection. The water system would be designed by the proponent's engineer. This existing system could supply adequate fire and potable water flow to the proposed development. (Conversation with Duane Huskey on 3/25/85). The system within the development would be maintained by the owners. The system within the Slade Way right -of -way would be maintained by Water District No. 75. Installation of the water system to serve the proposed development could have short -term impacts on vehicular travel on Slade Way where trenching is required within the right -of -way or across the road. During actual connec- tion of the project system to the District system, water service in the area could be interrupted for brief periods of time. Implementation of the proposal would result in a long -term commitment of the District water supply to serve the proposed development; however, as stated above, the District does not expect to experience difficulty in meeting long -range demands in the area. The proposed on-site system would comply with City of Tukwila fire flow and hydrant- spacing requirements, as well as with the requirements of the Washington State Department of Social and Health Services. The on -site system would comply with Water District No. 75 installation requirements including those to prevent a cross - connection between water and sewer. According to Washington Survey and Rating Bureau criteria, approximately 2100 gpm (see appendix for calculations) is the required fire flow for multi - family develop- ments of this type. The proposed system would meet the minimum criteria. Projected domestic water usage for the site should not exceed 0.04 mgd on a peak day (see appendix for calculations). Mitigating Measures: Installation of water - saving fixtures and devices such as flow restrictors in new dwelling units (at the discretion of the builder) could reduce water consumption, but the feasibility'and necessity of this is doubtful. -6- • 0 I .-__...� _ rho •ice �� - -. ` ----- AP. 11 /41 '/ EXISTING STORM SYSTEM & EASEMENT INTERCEPTOR TRENCH __________ EXISTING STORM • N-4/A4 4tv44464/ O�v / G / \�, CONTROL MH ° 0-- VALLEY VIEW ESTATES SITE UTILITY PLAN DETENTIi PIPE EXISTING SEWER & EASEME0- '• PROPOSED Amon.... PROPOSED mummy PROPOSED ■\\\N, PROPOSED ■.I■ PROPOSED LEGEND FRENCH DRAIN INTERCEPTOR TRENCI- STORM LINE WATER LINE SANITARY SEWER LIN APPENDIX VALLEY VIEW ESTATES Preliminary Storm Drainage Analysis Storm Drainage Criteria The storm drainage system for the proposed project as previously described shall be based upon the following criteria. These criteria and method of analysis are quoted from the "Requirements and Guidelines for Storm Drainage Control in King County ", Division of Hydraulics, King County, May 1979 and that document should be referenced for additional information. 1. Runoff Rate Q = CIA where 0 = Rate of flow in cubic feet /second C = Runoff co- efficient based on relative imperviousness of the area i = Rainfall intensity in inches /hour for Seattle area A = Area of runoff in acres 2. Calculation of drainage pipes, ditches and other facilities will be completed, based on requirements with design of the final facilities. Southn Basin Area in basin = 4.4 acres Travel length = 500 feet Velocity (slope average 25 %) = 1.3 FPS (bare ground) Travel Time = 10 + 500 = 16.4 minutes 1.3(60) it = 1.25 inch /min. i25 = 1.55 inch /min. "c" existin = .15 Seattle) g Existing 10 -year peak rate = 0 existing= CiA = (.15)(1.25)(4.4) = 0.83 cfs Existing 25 -year peak rate = 0 existing = 0.15 (1.55)(4.4) = 1.02 cfs CFuture = 2.1 ac (0.90) + 5.0 ac (.15) = 0.37 7.1 Future 10 -year peak = (.37)(1.25)(4.4) = 2.04 cfs Future 25 -year peak = (.37)(1.55)(4.0) = 2.52 cfs Qo = °existing„ _ Area ( future) 0.83 = 0.51 T = -25 + 1763 = 34 minutes TTST 4.4(0.37) V = 2R20(34) - 40(0.51) 34 = 931 ft.3 /Acre Vs 25 + 34 ("c" future) VT = 931 (4.4)(.37) = 1516 ft.3 detention volume North Basin Area in basin - 2.8 acres Travel length = 500 feet Velocity = 1.3 fps Travel Time = 10 + 500 = 16.4 minutes 1.3(60) i10 = 1.25 inch /min. i25 = 1.55 nc" existing = .15 Existing 25 -year peak = 0.15 (1.55)(2.8) = 0.65 cfs Existing 10 -year peak rate = °existing = CiA = (0.15)(1.25)(2.8) = 0.53 cfs Cfuture = 2.1(0.9) + 5(1.5) = 0.37 7.1 Future 10 -year peak = .37 (1.25)(2.8) = 1.30 cfs Future 25 -year peak = .37 (1.55)(2.8) = 1.61 cfs Qo = °existing = .53 = 0.51 Area ( "c" future) 2.8(.37) T = -25 + 1762 = 34 minutes 051 Vs = 2820(34) - 40(0.51)34 = 931 ft.3 /Acre ( °c"existin ) 25 + 34 g VT = 431(2.8).37 = 965 ft.3 detention volume AlCI:N.fei . z STEPAN & ASSOCIATES, Inc. April 16, 1985 Mr. Richard Johnson Design Engineer Dept. of Transportation State of Washington 9611 S.E. 36th Street Mercer Island, WA 98040 Reference: Valley View Estates E.I.S. Dear Richard: After discussions with the soils consultant, GeoEngineers, we would like to request on behalf of Puget Western, Inc. the following: 1) The horizontal drains be flushed and cleaned. Also do the horizontal drains consist of 10' of stainless steel screen and the remainder tight - line to the vertical wells? The horizontal drainage and /or vertical wells appear to be plugged since the water level in the wells is at a higher level than where the horizontal drains intersect the vertical wells. 2) The vertical wells be flushed and cleaned. Also bolt in place and lock the covered plates on the wells. 3) What is the status and condition of the pumps that are currently in the wells. What is the status of the condition and location of those that have been removed from the wells? 4) A repair and flushing of the original test drains shown on the attached sketch. Also any documents as to where these drains connect to. If you have any questions, please contact Jack Tuttle or Gordon Denby at 881 -7900 or myself at 682 -4771. Very truly yours, STEP N 8 AS IATES, INC. Glenn McKinney, P.E. Vice President GM /gc cc: Joel Haggard, Attorney Tom Russell, Puget Western Jack Tuttle, GeoEngineers • 930 South 336th Street, Suite A • Federal Way, Washington 98001 • 1 acoma 97.7850• Seattle 681 4771 • FIGURE 2 . «'r crows - • / • _( Project Site • Approximate Extent of Slide 4- 20-61 0 100 200 300 t i t Scale In Feet Reference: Drawing entitled "Plan of Completed Remedial Measures" by Shannon & Wilson dated March 31. 1966. aftedis was. Legend: Horizontal Drains (existing) o Original Test Drains o------Recommended Drain (Grade: 1 -3%) • Cylinder Pile Wall • ma Existing or Proposed Right of Way ♦ Additional Vertical Drains (6 -9 in. dia.) • Large Diameter (5') Deep Well 4110. Final Excavated Slope (horizontal:vertical) • Piezometer Installed During 1966 Investigation GeoEngineers Inc. 1 HORIZONTAL DRAIN AND WELL SYSTEM SUR'.l 1INC 56� t \l.l\t 1 RINI. I 7 STEPAN & ASSOCIATES, Inc. April 17, 1985 Mr. Duane Huskey, P.E. Water District No. 75 P.O. Box 68100 Riverton Heights Station Seattle, WA 98168 Reference: Valley View Estates Water Service Dear Dwain: As per your letter of April 10, 1985, an 8 -inch main, not a 6 -inch main, would be installed in Slade Way. Also attached for your review is a rough draft of the water portion of the Valley View E.I.S. Please call me if you have any questions or comments. Very truly yours, STEPAN & ASSQCIATES, INC. Glenn McKinney/P.E. Vice President GM /gc Attachment • 930 South 3.3hth Stre'et, Suitt' A • Federal iV i W.l.hingt(n l811U t • 1.ecoma '117 78511. Seattle 682 •1'71 • SURVEYING kNGINEERING o z ( • 930 South 336th Street, Suite A • Federal Way, Washington 9800 • l acoma. 927. 7850. Seattle. 682-4771 • Reference: Water Service for Proposed Valley View Project / Slade Way Dear Duane: As per our discussion, a new 6" main from your existing 6" line in South 160th Street to your existing 8" main in South 166th Street would provide adequate fire (2100 gpm) and domestic flow. Water District No. 75 would pay for the portion of the new main in 54th Avenue. If you have any questions, please contact me. GM /gc cc: T. Russell J. Haggard Very truly yours, STEPAN & ASSOCIATES, INC. Glenn McKinney, P.E. Vice President DAN N CAL.DWELL. President GEORGE L. BLOMBERG. Secretar■ JERRY P. HARRIS. Commissioner /Wafer 2)ijfricI flo. 7.5, _ kn9 Coun/l, rep one 824.037' " EC ;E1 ?0. Riverton Heignrs .,;rs?i , SEATTLE. WASHINGTON 98168 April 10, 1985 Stepan & Associates, Inc. 930 South 336th Street Suite A Federal Way, Washington 98003 Attention: Mr. Glenn McKinney, P.E. Vice President Dear Glenn: KEN HALL Manage t KENT HAYDEN Controller DUANE HUSKEY Engineer CLIFF BARTLETT Superintendent Office 198::i : ?8t i Avent : So. r.7 � � �()( r jj i,�' c There seems to be some misunderstanding of the information, either the way I told it to you or the way you heard it, on the new main for the Valley View project on Slade Way. The calculations that we performed showed that by extending a new 8" line from our existing 6" line on South 160th Street, the 2,100 gpm domestic fire flow could be met. The portion of the main along 54th Avenue South is not scheduled for construction at this time but would be connected to the main installed for this project. Please call me if you have any questions. Sincerely, Duane Huskey,(P.E. DH:tmw cc: Ken Hall, Manager, WD #75 w, R- DISTRier NO. 76 LIMM Oo C ITEKS ► JOT'Tad 19863 28th Ave. South Seattle, Washington 98188 Bus: 824-0375 7 j DATE ..... JOU NO. ATTENTION CCEA/41 ,Arck,...vcy" RE: ZEI /E i E l AiE L C c .4. ,' S (v4ccEy ✓ . Ec t-s 774 .j NE ARE SENDING YOU 2r Attached ❑ Under separate cover via O Shop drawings O Copy of letter O Prints ❑ Change order ❑ Plans ❑ Samples ✓� - ' -y /YID the following items: 0 Specifications COPIES DATE NO. DESCRIPTION THESE ARE TRANSMITTED as checked below: ❑ For approval Cre or your use As requested ❑ For review and comment ❑ Legal description ❑ Approved bills ❑ FOR BIDS DUE ❑ Approved as submitted ❑ Approved as noted ❑ Returned for corrections ❑ Tracings ❑ Quotation ❑ Resubmit copies for approval ❑ Submit copies for distribution ❑ Return corrected prints ❑ Signature ❑ Payment 19 ❑ PRINTS RETURNED AFTER LOAN TO US 1EMARKS OPY TO SIGNED: 9'7/ ��w DAN N. CAI. DWELL President KEN HALL GEORGE L BLOMBERG, Secietary Manage JERRY P. HARRIS, Commissioner KENT HAYDEN Controller ?Vattr l)ijIrid no. 7.5. . lit n cf (oun f y Telephone 824C_ January 11, 1985 DUANE HUSKEY Engineer CLIFF BARTLETT Superintendent P C` 3t . Rtverto;; He,p';s c ;, Office ,gnc;: 78th Aven:ic Sc. SEATTLE. WASHINGTON 98168 Stepan & Associates 930 South 336th Street Federal Way, Washington 98003 Attention: Mr. Glenn McKinney • Re: Water District No. 75 Comp Plan 1981 -1985 Dear Mr. McKinney: Please find enclosed a copy of Page 102 of Water District No. 75's current Comprehensive Plan. We show extending 3,800 lineal feet of 8" ductile iron main along Slade Way. This would loop our facilities at 51st Avenue South and South 166th Street. Our existing 6" C.I. along South 160th Street could possibly be used depending on fire flow requirements for this development. Hopefully, this information is what you required. Please call me should you have any questions. Sincerely, �LCGw- Duane Huskey,`P.E. DH:tmw Enclosure cc: Ken Hall, Manager, WD #75 TIMETABLE OF IMPROVEMENTS A. The order of listing below is a tentative priority listing subject to change, based on a continuing evaluation of needs. B. The costs shown are estimated at 1981 prices. For each subsequent year prior to construction, an estimated 10% must be added to this cost due to inflation. It is thus recommended that an annual in- crease of 10Z be made to the Replacement and Renewal Fund, in order to keep pace with increased construction costs. TABLE 23 Replacements and Renewals - Immediate (1981 -1985) $380,000 /Year EST. 1981 ALONG FROM TO LENGTH SIZE COST *S. 166th St. 32nd Ave. S. 34th Ave. S. 1100' 8" $ 24,200 S. 170th St. 40th Ave. S. 49th Ave. S. 2,700' 8" 59,400 *S. 170th St. 49th Ave. S. 51st Ave. S. 630' 8" 15,100 S. 170th St. 51st Ave. S. 53rd Ave. S. 500' 8" 11,000 *S. 175th St. 33rd Ave. S. 34th Ave. S. 320' 8" 7,040 *S. 192nd St. Des Moines Way 16th Ave. S. 1,050' 8" 23,100 S. 208th St. Pac. Hwy. S. Military Rd. S. 2,300' 8" 50,600 *S. 236th St. 10th Ave. S. : 13th P1. S. 730' 12" 24,090 Slade Way 51st Ave. S. 54th Ave'. S. 3,800' 8" 83,600 6th Ave. S. Cul -de -Sac S. 200th St. 300' 12" 9,900 *33rd Ave. S. S. 170th St. S. 175th St. 1,740' 8" 38,280 42nd Ave. S. S. 160th St. S. 164th St. 1,300' 8" 28,600 *42nd Ave. S. S. 272nd St. S. 276th St. 1,315' 8" 28,930 42nd Ave. S. S. 276th St. S. 280th St. 1,300' 8" 28,600 *46th Ave. S. Star Lake Rd. S. 280th St. 1,290' 8" 28,380 *53rd Ave. S. S. 168th St. S. 170th St. 660' 6" 10,840 Military Rd. S. S. 224th St. Kent -Des Moines Rd. 2,700'. 8" 59,400 *Bow Lake Tank Area Fressure Zone Modification 60,000 Subtotal $591,060 *1981 Projects JERRY P. HARRIS. President GEORGE BLOMBERG. Secretary DAN CALCWELL. Commissioner iVater 2Li1ric! no. 75, _luny County Teteonone 8240375 January 4, 1985 KEN E. HALL Aam n.st•3tive Maniger MARION HARTER C "!:e Manage' P.O. Box 68100. Riverton Heights Station Office 19863 28th Avenue So. SEATTLE. WASHINGTON 98188 Mr. Brad Collins, Planning Director City of Tukwila Planning Department 6200 Southcenter Boulevard Tukwila, Washington 98188 R. W. Thorpe & Associates 815 Seattle Tower Third & University Seattle, Washington 98101 Re: Draft EIS, Valley View Estates 1984 Gentlemen: I j Jf- PS- - - - -_. Water District No. 75 finds it highly impractical in view of the newly - passed Water System Coordination Act for the City of Tukwila to extend a dead end main into our corporate boundary to serve property where the District has existing facilities. Our Comprehensive Plan contemplates looping our existing system from Slade Way along 54th Avenue South to connect to an existing line on S. 166th Street. We are not anxious to continue the flushing programs necessary for the existing dead end mains. Another dead end main installed using City of Tukwila facilities will only contribute to an existing bad situation. The District feels it may also be appropriate to discuss with Tukwila an intertie at the PRV facility on 53rd Avenue South. We do not desire this potential customer to withdraw from our corporate boundary, nor are we interested in a service area agreement to allow Tukwila to serve a customer we are better equipped to serve. City of Tukwila Planning Department and R. W. Thorpe & Associates Pace 2 January 4, 1985 We would be more than happy to discuss this project with the City of Tukwila Planning Department or the developer at their convenience. Please call Duane Huskey or myself should you have any questions. Sincerely, 2 en Hall Administrative Manager KH: tmw cc: Dr. Herman Allenbach Puget Western, Inc. Paula Russell, Boundary Review Board COMMISSIONERS: e w BUTTERS BETTY LUNZ NuCNAEL J WEST vU• SEWER DISTRICT 14816 MILITARY ROAD SOUTH P.O. BOX 68063 SEATTLE WASHINGTON 98168 TELEPHONE: 2423236 January. 23, 1985 Brad Collins, Planning Director City of Tukwila Planning Department 6200 Southcenter Boulevard Tukwila, Wa. 98188 COMMENT ON VALLEY VIEW ESTATES DRAFT EIS SUBJECT: Sanitary Sewers MANAGER: JAN 2 81985 T. J MATELICH The comments made herein are in reference to the 12" sanitary sewer line owned and operated by the Val Vue Sewer District that traverses the proposed Valley View Estate site. The District and its consulting engin- eering firm, Yoshida, Inc., has reviewed the Draft EIS and the easement for the District's sewer line and has concluded that to case the sewer in those areas where buildings are to be built over the sewer may not be the best method or the most cost effective. Attached is a copy of the site utility plan (Figure 16) on page 130. The District's recommended method is to relocate a portion of the existing 12" sewer line. This is indicated in orange on the revised site utility plan. The relocation will eliminate the potential violation of the City's policy that prohibits placement of buildings on top of sewer lines. It will also eliminate the potential of a possible sewerage spill that could occur during the encasement of the sewer line. The relocation construction of the sewer line can occur without any disruption of service in the existing line. Should any further information or elaboration be required on this matter, please contact this office. Sincerely, VAL VUE SEWER DISTRICT MATELICH Manager TJM /gbs Enc. • EXISTING STORM SYSTEM & EASEMENT EXISTING STORM - - - - -- - i --- ------ 53' iron() S -----w-w \w����wwNNw I. CONTROL t4H / OO�SO EXISTING SEWER & EASEMEN'r VALLEY VIEW ESTATES SITE UTILITY PLAN FIGURE 16 8� LEGEND ImmimPROPOSED STORM LINE ■ILXVIOROPOSED WATER LINE ■II• ■PROPOSED SANITARY SEWER L i r. REPORT GEOTECHNICAL AND HYDROLOGICAL STUDIES PROPOSED VALLEY VIEW ESTATES SLADE WAY AND 53RD AVENUE SOUTH TUKWILA, WASHINGTON FOR DR. H. M. ALLENBACH NOT :7,0 FEB 1 1989 I PUGET WESTERN INC. FEB 31989 1 PLANNING DE: GeojEngineers April 25, 1985 Stepan and Associates, Inc. 930 South 336th Street, Suite A Federal Way, Washington 98003 Attention: Mr. Glen McKinney Gentlemen: We are pleased to submit two copies of our "Report, Geotechnical and Hydrological Studies, Proposed Valley View Estates, Slade Way and 53rd Avenue South, Tukwila, Washington ". This report was developed in two phases. The scope of services for the first phase was outlined in our proposal dated August 9, 1983, and the Phase 1 report was presented on February 17, 1984. This report replaces and supplements our Phase I report. The Phase II services consist of collecting additional data and expanding some of our previous analyses to respond to comments raised during hearings on the Draft Environmental Impact Statement. These services were performed under a. confirming agreement dated July 16, 1984 and were expanded by verbal authorization from Mr. Tom Russell, project manager for Puget Western, on several occasions. We have enjoyed working with you on this project and are looking forward to continuing our relationship during the instrumentation installation and monitoring, and construction phases of the project. Should you have any questions or need additional information, please call. Yours very truly, ineers, Inc. . Tuttle ncipal GMD:JKT:da File No. 523 -02 cc: Puget Western (8) Attn: Mr. Tom Russell eegift Geo Engineers T A B L E O F CONTENTS Page No. INTRODUCTION 1 ISCOPE 2 REVIEW OF SITE HISTORY 4 USE OF THIS REPORT 31 List of Figures IFigure No. ISITE PLAN 1 HORIZONTAL DRAIN AND WELL SYSTEM 2 IEXISTING ON SITE HORIZONTAL DRAIN LAYOUT 3 CROSS SECTION A -A1' 4 IISCHEMATIC OF PROPOSED INTERCEPTOR DITCH 5 Geo o ®Engineers ' APPENDIX A Page No. FIELD EXPLORATIONS AND LABORATORY TESTING A -1 FIELD EXPLORATIONS A -1 LABORATORY TESTING A -1 Appendix A Figures Figure No. ' UNIFIED SOIL CLASSIFICATION SYSTEM AND KEY TO SAMPLE DATA A -1 LOGS OF EXPLORATION A -2 Time A-19 Geobv Engineers REPORT GEOTECHNICAL AND :HYDROLOGICAL STUDIES PROPOSED VALLEY VIEW ESTATES SLADE WAY AND 53RD AVENUE SOUTH TUKWILA, WASHINGTON FOR DR. H. N. ALLENBACH INTRODUCTION This report presents the results of our geotechnical and hydrological studies of the site proposed for construction of Valley View Estates. The report replaces and supplements our report dated February 17, 1984. Revisions to the report include additional water level data obtained since issuance of the initial report. We also address, in expanded detail, specific issues raised during review of the Draft Environmental Impact Statement. The site is located adjacent to the west right- of-way for Interstate Highway No. 5 and is bounded on the south by Slade Way and on the-west by Slade Way and 53rd Avenue South, as shown on the Site. Plan, Figure 1. The proposed development includes construction of 18 six -unit residential structures together with associated roadways, parking areas and utilities. The units will be stepped into the hillside, requiring varying depths of cut. Some cutting and filling will also be required to construct the roadways and parking areas as well as to establish reasonable grades around the various buildings. Wood frame construction which will result in relatively light foundation loads is planned. The proposed residential property is located within a very large, prehistoric, landslide zone. Also, a substantial portion of the property was involved in the landslide which occurred in 1960 as the result of excavation of borrow material which was used for fill in the Andover Industrial Park. The stability of this and adjacent properties on the southwest portion of the interchange of the freeway with State Route 405 has been improved by the remedial drainage measures which were installed by the Washington State Department of Transportation (WSDOT) during construction of Interstate Highway No. 5. No evidence of recent deep- seated movement was noted during GeoWW Engineers our site examinations. The WSDOT drainage facilities include systems of horizontal drains and vertical wells, a number of which exist immediately east of this property. SCOPE The scope of services for these studies was developed and executed in two phases. Phase I was developed following a meeting on August 2, 1983 of the various parties involved in assembling information for the Environmental Impact Statement for this project. Phase I reflected our assessment of the extent of study which we considered to be appropriate for this project, based on studies made for the 1960 -61 landslide by members of our staff while employed with Dames & Moore and a review of existing surficial site conditions by our firm in 1982. Our proposal for Phase I was submitted in a letter dated August 9, 1983. We received authorization to proceed in September 1983. The purpose of the Phase I services was twofold: 1) to develop pertinent information on soil and ground water conditions for inclusion in the Environ- mental Impact Statement, and 2) to develop further design criteria, as appropriate, for the geotechnical aspects of the project. The Phase I scope of services includes: 1. Exploring subsurface soil and ground water conditions by drilling a series of test borings from which representative soil samples were obtained and in which piezometers were installed to monitor ground water conditions at appropriate levels. 2. Evaluating pertinent physical and engineering characteristics of the soils from the results of laboratory tests. 3. Reviewing information available from the Washington State Department of Transportation on the subsurface drainage system which was installed in the site area during construction of Interstate Highway 5. 4. Defining, to the extent possible, past landslide history of the immediate area. 5. Evaluating the overall stability of the project site for present geotechnical and hydrological conditions. 2 Geok En Engineers 6. Evaluating pertinent design criteria for the geotechnical elements of the project, including stability of cut and fill slopes, design criteria for shallow foundations, retaining structure design criteria, earthwork procedures, and site drainage requirements. In addition, our scope of services for Phase I was expanded to include the installation of a slope indicator casing and obtaining an initial set of readings at Boring F. This installation has been made in an area of past sliding, but lies above the area of planned development so that information from subsequent readings will provide a means of monitoring any movements of the hillside in the area between Slade Way and the planned residential development. The Phase II scope of services was developed following public hearings on the Draft EIS. The scope of services was developed with Mr. Tom Russell, project manager for Puget Western, Inc. and was authorized verbally. The purpose of the Phase II services is to gather additional information on the geohydrologic regime in the hillside and to respond to comments on the Draft EIS. The Phase II scope of services includes: 1. Obtaining an additional set of readings of the piezometers and the slope inclinometer. 2. Flushing out several piezometers installed by others adjacent - to the site during investigations for the construction of 1 -5. 3. Obtaining additional information on the Washington State Department of Transportation well system including sounding the depth and recording the water levels in the wells. 4. Reviewing the Phase I assessment of the geohydrologic regime on the hillside with regard to the additional water level data. 5. Conducting additional static stability analyses to evaluate the stability of the hillside relative to pre- and post -drain installation and to develop criteria for identifying the extent to which water levels in the hillside can safely rise before remedial drainage measures would need to be initiated. 6. Conducting dynamic stability analyses to evaluate the hillside stability under earthquake conditions. 3 'Geov Engineers 7. Expanding our Phase I recommendations for monitoring and instrumen- tation of site stability prior to, during, and following construction. REVIEW OF SITE HISTORY The review of the site history included examining files of the Washington State Department of Transportation in Olympia and various soils reports pertaining to the site specifically and to the adjacent slope stabilization measures accomplished during I -5 construction. The soils reports that were reviewed include: - "Report of Stability Investigation, Borrow Area Slide, 54th Avenue South and South 162nd Street; Tukwila, Washington ", by Dames & Moore, December 1, 1960. - "Report of Soils Investigation, Earthslide, South 162nd Street Near 53rd Avenue South, Tukwila, Washington ", by Dames & Moore, June 27, 1961. - "Report on Foundation Investigation, Existing Slide Area, Tukwila Interchange, PSH -1 (SR5) ", by Shannon & Wilson, June 12, 1964. "Summary Report, Slope Stability Investigation, Tukwila Interchange (SR5) ", by Shannon & Wilson, April 14, 1966. - "Summary Report, Soil Conditions and Earth Movements, Vicinity .of the Tukwila Interchange ", by Shannon & Wilson, June 21, 1968. - "Geotechnical Design Consultation, Proposed Residential Development, Slade Way and 53rd Avenue South, Tukwila, Washington ", by GeoEngi- neers, May 3, 1982. The listed reports document a large earthslide that occurred at the site in 1960 as material was being excavated from a borrow area immediately downslope of the site. The extent of the slide is well documented in the 1960 and 1961 reports and is shown in Figure 2. The slide covered the southern two - thirds of the site as well as extending another 200 feet upslope from the western boundary of the site. Measurements during October 1960 indicated that the slide area was moving an average of 0.5 feet per day. Movements continued at a diminished rate in 1961. Slope indicator measurements taken in conjunction with the Dames & Moore studies indicated that movements were occurring in a shear zone 25 4 Geo Engineers to 40 feet below the ground surface through the central portion of the slide. In addition, the shear zone was indicated to consist of clayey soil underlain by a layer of waterbearing sand. The 1960/61 slide movement had resulted from the combined effect of excavation and the substantial artesian pressures existing in the waterbearing sand layer. The remedial measures considered were based on reducing the hydrostatic pressure within the waterbearing sand layer which appeared to immediately underlie the failure surface. Deep wells as well as horizontal drains and drainage trenches were considered. A series of horizontal drains was installed in the summer of 1961, together with some regrading of the borrow pit area. A plan from the Shannon & Wilson 1964 report showing the locations of the horizontal drains is presented in Figure 3. Altogether, 20 6- inch - diameter slotted pipe drains with lengths from 100 to 150 feet were installed. Eight of the drains were located along the toe of the roadway fill in the southwest corner of the site, while the remainder were located in the south - central portion of the site. The flow from the drains does not appear.to be piped and is probably responsible for some of the existing wet areas at the site. The 1966 and 1968 reports are related to the overall stability of the hillside, both to the north and below this site, as it related to con- struction of the I- 5/SR405 interchange and related roadways. At that time there had been considerable landslide activity not only at the project site but north and northwest along the hillside. Ten to twelve landslides of various dimensions were observed in these areas. The 1968 report shows several recent slide scarps at the project site. With one exception, all of these were less than 200 feet long and were aligned along the contour; however, one was approximately 700 feet long and was aligned approximately at 45 degrees to the contours in the northern third of the site. This scarp appeared to be the northern boundary of a large slide, possibly the 1960 -61 slide. The proposed remedial measures consisted of an extensive subsurface drainage system of vertical wells tied into horizontal drains and cylinder pile wall retaining structures as shown in Figure 2. In addition, an inter- ceptor drain, shown as the D -3 drain on Figures 2 and 3, was installed. 5 Geoko Engineers These remedial measures were initiated by the Washington State Department of Transportation and were subsequently monitored and reported on by Shannon & Wilson. The WSDOT drain system consists of a series of 5- foot - diameter wells tied into horizontal drains originating at the retaining wall along Klickitat Drive, as shown in Figure 2. The wells are located just east of the site. In addition to the large diameter wells, a number of small diameter vertical drains were installed in between the large wells as shown in Figure 2. Based on information in the Shannon & Wilson reports, the horizontal drains consist of 1 -1/2- inch - diameter unperforated plastic pipe with 10 -foot- long stainless steel well point tips. In addition, it was recommended that every fifth drain have a section of stainless steel screen at mid- length. We have not located any records that verify whether or not this was done. Information, including elevations;, grades and lengths of the WSDOT horizontal drain and vertical well system, is presented in Table B -4 in Appendix B. Based on inspection of the wells, it appears that the original pumps are still in place in approximately 70 percent of the wells. The pumps and outlet pipes have been removed in the other wells. The condition of the in -place pumps is not known. Inspection of the outlets of the horizontal drain system revealed 42 outlets through the cylinder pile retaining wall along Klickitat Drive (see Figure 2). The length and orientation of any drains in these outlets other than those that lead to the wells is unknown. There may be short horizontal drains to drain immediately behind the wall or replacement drains to the wells. The extra outlets may also be weepholes to drain the zone behind the wall. Approximately half of the 42 drain outlets, primarily to the north, were dry at the time of our most recent visit (April 12, 1985). Flow through the other weepholes varied from a drip to about one . gallon per minute. There was also significant flow between the wall panels in two places. At one location, the flow between the panels was estimated to be 4 to 6 gallons per minute. The 1968 Shannon & Wilson report also identifies a system of original test drains that were installed by WSDOT just east of the eastern property line and south of the horizontal drain /vertical well system (see Figure 2). 6 Geow® Engineers Our examination of the portions of this drain system still in evidence indicates that they are still at least partially functional. These drains consist of 1 -1/2- inch - diameter PVC pipe. The outlets are connected to buried manifolds, three of which discharge into a drainage gully. The fourth manifold was unable to be located. Approximately 60 percent of the drains were located, of which approximately 20 percent appear to be damaged and in need of repair. Local sloughing and erosion has occurred at the drain outlets in several places. Flows from the three manifold outlets ranged from approximately 0.25 to 3 gallons per minute. The 1966 Shannon & Wilson report summarizes potential failure modes for the landsliding on the hillside and, like the 1960 and 1961 studies by Dames & Moore, concludes that the mode of failure at the project site is due to the presence of a clayey silt underlain by sands with artesian pressures. The report includes classification and average strength values for the important materials in the hillside. These data were used in our studies. The Shannon & Wilson report concludes that the I -5 project area slopes (including the area in which- the - drains and wells are installed) are stable for the static conditions then (1968) existing. They also concluded that the soil materials in the slopes "are unlikely to be significantly affected by seismic activity ". Some evidence of near - surface movement, mostly in the form of shallow creep and flow slides, was noted in our examination of the . site prior to preparing our consultation report of May 3, 1982. A recent scarp was observed a short distance east of Slade Way. The scarp is about 200 feet long and varies from about 12 to 20 inches in height. The downslope extent of the slide appears to be limited to the upper portion of the property in which no construction is planned. The slide was estimated to have occurred in 1981 or earlier, based on the extent to which vegetation had reestablished itself along the scarp. SITE CONDITIONS A plan of the site is shown in Figure 1. The site covers approximately 7 acres and is non - uniformly shaped, being bounded on the south and west 7 Geoe, Engineers by Slade Way and on the east by the Interstate Highway No. 5 right -of -way. A sanitary sewer runs along contour through the eastern portion of the site. There is also evidence of the D -3 drain, as shown on Figure 2. The site slopes moderately to the east and northeast with isolated areas becoming moderately steep. A large drainage swale transects the southern portion of the site, resulting in the sewer alignment curving to the west around this swale before swinging to the northeast. There are three benches on the site that appear to be manmade. The presence of the benches may be indicative of remedial grading following previous slide activity. The lowest bench appears to have been constructed during the installation of the sanitary sewer line and essentially follows the sewer alignment to a point where the sewer line crosses the property line at the center of the eastern property line. The ground surface downslope from the sewer bench in the southeast corner of the site is moderately steep. A second bench starts at the southern property line slightly upslope from the sewer line bench and is oriented approximately parallel to the sewer line bench for approximately one -third the length of the site at which point it disappears. The third bench is located in the center of the site and may have been constructed during installation of an old surface drain in this area. Vegetation consists of areas of very dense berry vines, some exceeding 10 feet in height, fairly dense alder groves, scattered evergreen trees, particularly on the western portion of the site, and occasional horsetails, which are indicative of wet ground. Most of the alder trees located on the middle to eastern portion of the site appear to be fairly young, indicating that the site was likely stripped of vegetation following the slide in 1960 -61. Wet surface conditions were observed over much of the site during our field explorations in October 1983. Some of these appear as seeps or springs, possibly originating from the horizontal drains installed in 1961 as shown on Figure 3. A corrugated metal pipe stormwater drain is located at the intersection of Slade Way and South 160th Street and is reported to parallel 53rd South for a short distance before turning east and tying into the D -3 drain. 8 Geokol Engineers The drain was leaking several gallons per minute at the time of our explor- ations. Flow from this drain was apparently being collected by the upper portion of the D -3 drain. SUBSURFACE CONDITIONS Subsurface conditions were explored at the site by drilling 8 borings using a truck - mounted, hollow -stem auger drill rig. The borings were drilled during October 13 to October 21, 1983. Because of wet conditions at the site and relatively steep slopes, a dozer was required to assist the drill rig in moving around the site. An engineer from our staff established the boring locations, maintained logs of the explorations, and obtained relatively undisturbed samples for observation and laboratory testing. The boring locations, as subsequently surveyed by Stepan & Associates, Inc., are shown on Figure 1. Details of the field explorations, along with the boring logs edited to reflect laboratory examination and testing, are presented in Appendix A. Piezometers were installed in all borings except Boring F where an inclinometer casing which will permit future moni- toring of slope movements was installed. Both deep and shallow piezometers were installed in Boring J. Details of the piezometer and inclinometer instrumentation are presented in Appendix B. Subsurface conditions at the site were interpreted from borings in the 1960 and 1961 investigations and from the current drilling program. Three major units were identified at the site as follows: UNIT A: Fill and /or slope debris, probably native to the site and consisting of loose to medium dense silty fine to medium sands. Thickness varies between 5 and 10 feet. UNIT B: Gray silt interbedded with fine to medium sand. The gray silt varies in consistency between medium stiff to very stiff, generally becoming stiffer with depth. The silt has some zones which contain a trace to some clay. Slickensides are present throughout the unit as well as randomly oriented contacts between different gradations of materials. The sand layers appear to vary from 1/8 of an inch to one to two feet in thickness and are generally saturated. 9 .Geo kleot Engineers UNIT C: Gray sandy silty gravel and gray gravelly sand with some silt. Consistency varies from dense to very dense and unit is generally saturated. Unit B generally grades into Unit C and is separated by a layer of gray fine to medium silty sand in some of the borings. The three units vary significantly both in depth and elevation across the site. As shown in a typical cross section in Figure 4, the units tend to follow the existing topography and slope down to the east. The thickness of the gray silt (Unit B) is less toward the south (25 feet in Boring C) and increases to the north (89 feet in Boring K). The dip of the surface of Unit C is to the northeast and may represent an erosional feature that occurred before deposition of Unit B. GEOHYDROLOGICAL AND SURFACE WATER CONDITIONS Two separate and independent hydrologic regimes exist at the site. The upper regime, existing within Units A and B, is influenced by surface water runoff, seepage from upslope, and direct precipitation. Seepage . volumes are small due to the relatively low permeability of these soils. Water pressures in this regime are likely to be hydrostatic. In contrast, the lower regime existing within Unit C is influenced primarily by subsurface ground water flow. The source of water is not known; however, it is likely that it is upslope and to the west or southwest of the site. Water pressures in this regime were artesian at the time of the 1960-61 slide. The permeability of the soil in the lower regime (Unit C) is significantly higher than the soils in the upper regime and seepage volumes would be expected to be cor- respondingly higher. The original water table at the site has . been modified on three occasions in the past 25 years. The first modification occurred after the 1960 -61 slide when several on -site horizontal drains were installed in 1961 on the slope (see Figure 3). These were installed to alleviate the artesian pressures in Unit C and arrest the hillside movements. The second modification of the water table at the site occurred in 1966 when the Washington State Department of Transportation installed a 10 Geb ittod Engineers series of large- diameter wells (see Figure 2). These wells were then pumped during construction of a cylinder pile wall along Klickitat Drive to the east of the project site. The third and most recent modification of the ground water regime occurred near the end of construction of the cylinder pile wall when horizontal drains were drilled to intercept the vertical wells and the pumps in the wells were subsequently switched off. Water levels in the two ground water regimes were measured using the piezometers installed in our borings in October 1983, three of the piezometers installed by Shannon & Wilson in 1966 which we were able to locate, and the WSDOT vertical wells. Our piezometers are installed in Unit C, the lower ground water regime, with the exception of the second piezometer in Boring J which was installed in Unit B, the upper ground water regime. The piezometer levels in our borings were originally measured on November 18, 1983 and subsequently measured on three occasions between November 30, 1984 and March 12, 1985. These data are presented in Table B -1 in Appendix B. Several readings of the Shannon & Wilson piezometers and the WSDOT wells were also taken during this period. These data are presented in Tables B -2 and B -3 in Appendix B. The Shannon & Wilson piezometers were flushed in March 1985. The piezometric data collected from November 1984 to March 1985 indicate relatively stable water levels in the lower ground water regime (Unit C) at the site. Water level depths range from 29 to 77 feet below the ground surface at the site and 26 to 55 feet as measured in the Shannon & Wilson piezometers east of the site. The water level data from the WSDOT wells is less consistent and it appears that several wells or horizontal drains are plugged. This is discussed further in the section on "Evaluation of 1 -5 Drain System ". In the upper ground water regime (Units A and B), the water levels are expected to be variable, ranging from the ground surface to depths of ten or more feet, depending largely on local topography, seasonal rainfall, and other factors. In Piezometer J, the water depth has been stable over the last six months at a depth of 9 feet. 11 Geo ff o Engineers STABILITY INTRODUCTION The purpose of the stability analyses is to assess the risk of instability of the hillside. The risk of sliding is related to existing conditions and to the effects of changing water levels in the hillside, as well as to earthquake activity. The analytical procedure consists of evaluating the gravitational force driving the soil downslope and the force of the soil (strength) resisting the sliding. The procedure also takes into account the effects that ground water conditions have on the resisting force. In general, the higher the water levels in the slope the lower the soil strength or resisting force. The risk of slide movement is expressed as a factor of safety which is defined as the ratio of the resisting force divided by the driving force. If the resisting force equals the driving force, the factor of safety is 1 and the risk of sliding is very high, whereas if the resisting force is greater than the driving force, the factor of safety is greater than 1 and the risk of sliding decreases as the factor of safety increases. Generally, slopes having a factor of safety greater than 1.5 are considered to have an acceptably low risk of sliding and are considered to be stable. Stability analyses were conducted to analyze both deep- seated and shallow- seated sliding. Details of the analyses including figures showing the failure surfaces analyzed are presented in Appendix C. A brief description and summary of the results of the analyses is presented below. DEEP- SEATED SLIDING The stability of the hillside was evaluated by considering the different topographic and ground water conditions which existed during the 1960 -61 slide and which exist in March 1985. The alignment of the section judged to be most critical of those analyzed is shown on Figure 1. The first set of analyses was conducted by assuming topographic and water level conditions recorded in 1960 and 1961 and back calculating the soil strength parameters required to yield a factor of safety of 1.0. 12 Geo 4 Engineers The soil strength parameters so determined are in good agreement and fall within the range of values reported by Dames & Moore and Shannon & Wilson and used in their analyses. The key parameter is the friction angle in the failure zone. The actual values used are as follows: Soil Along Soil Above Failure Zone Failure Zone 0 C 0 c GeoEngineers, Inc. 15 0 25 0 Shannon & Wilson, Inc. 14 0 Dames & Moore 14 600 0 = friction angle in degrees. C = cohesion in psf. 22° 350 700 0 The parameters determined in our studies were then used to analyze the slope stability for the March 1985 topographic and water level conditions inasmuch as we judge them to be a reasonable median value of the three sets of parameters reported. The results of these analyses indicate that . the factor of safety of the hillside for current conditions is in the range of 1.5 to 1.6 for the sections analyzed. The increase in factor of safety is, in our opinion, primarily due to the decrease in water levels caused by the WSDOT drain system, and represents an acceptable factor of safety in relation to the planned project. The impact of building loads on overall slope stability was also evaluated and found to have a negligible influence on the factor of safety. The possibility of a decrease in the factor of safety with a rise in the water level resulting from deterioration of the drainage system was also evaluated. The results of this evaluation (see Appendix C) indicate that the risk of sliding would become very high, i.e. FS = 1.0, if the water table were to rise an average of 20 feet above the March 1985 levels in the lower artesian aquifer. (See Tables B -1, B -2 and B -3.) The stability of the hillside was also evaluated for earthquake condi- tions. For this condition, the ground shaking during the earthquake increases the driving force. The seismic increment was approximated in the analysis by an equivalent static force proportional to a nominal horizontal ground acceleration (pseudo static method). For the project area, a horizontal 13 Geoff Engineers ground acceleration of 0.15g, where g is the acceleration due to gravity, was assumed. This value is typically used for seismic design in the Seattle area. It should be noted that the factor of safety calculated using the pseudo static method has a different connotation from that for static loading. Specifically, for the soil conditions which underlie the project site, a factor of safety of 1 or less represents a very high risk of sliding only during the ground shaking period. When the shaking ceases, movements should effectively also cease. This correlates with the observations of movements reported by a local resident upslope of the site after the 1965 earthquake. The actual amount of straining or displacement will depend on specific site and earthquake characteristics as well as the soil and ground water conditions. For the earthquake analysis, the shear plane was considered to have an additional strength component equal to 500 pounds per square foot of cohesion. This additional strength component is representative of the undrained soil conditions which would exist during the-short -term cyclic loading. A factor of safety of 1.13 was computed using the indicated earthquake loading and undrained strength parameters. This value is considered, in general practice, to provide a level of risk comparable to a factor of safety of 1.5 for static conditions. SHALLOW- SEATED SLIDING Slope stability due to shallow- seated sliding was evaluated using an empirical /infinite slope approach. This approach is based on reviewing existing slopes at the site and then analyzing different water level conditions, assuming a uniform infinitely long slope of similar material. Slope con- figurations at the site vary from about 2H:1V (horizontal to vertical) to 4H:1V. Perched water levels (upper regime in Units A and B) are variable across the site, ranging from the surface in areas below springs or flow from old horizontal drains to 9 feet (Boring J), or deeper. In some areas, evidence of surficial creep, as expressed by bending in tree trunks as they have grown, on the flatter but wetter slopes, indicates a lesser degree of stability than steeper, well- drained slopes on the site. 14 Geo kv. Engineers The importance of control of water levels on near - surface stability is illustrated using a 3H:1V continuous slope, the soil strength (0 = 25 °) assigned to the upper soils in the analysis of deep - seated stability and varying the perched water level. The effect of water level conditions on the factor of safety against sliding (ratio of resisting force to driving force is shown in the following table. Perched Water Level at ground surface 6 feet below ground surface 12 feet below ground surface Factor of Safety 0.7 1.1 1.4 The recommended final slopes for the site are 3H:1V or flatter. It is our conclusion that the stability of the slopes can be maintained at acceptable levels, provided that adequate drainage of the slopes is accomp- lished. The types of drainage facilities to be installed include an interceptor trench along the western property line, surface drains, a gully French drain, parking area French drains, subsurface wall drains and downspout drains. The extent of each of these facilities which should be installed to develop adequate drainage is discussed subsequently. The actual building loads will have a small favorable effect on the shallow slope stability, as the friction angle of the underlying soil is greater than the overall slope angle and the added vertical load will increase the resisting force more than the driving force will be increased (provided the load is applied slowly so that pore pressures are allowed to dissipate which is assumed to be the case for the type of construction and soils considered). There may be some destabilization of slopes during construction if slopes are oversteepened or adequate shoring is not used. Remedial measures including temporary backfilling, buttressing or otherwise increasing toe resistance may have to be initiated. Dynamic loading during an earthquake decreases the stability of slopes and may result in movement of any marginally stable slopes around the perimeter of the project. As described previously, the sliding should be limited to the duration of the earthquake. Resistance to sliding of individual structures requires analysis on a site - specific basis. This analysis should 15 Geo ` Engineers be conducted by GeoEngineers, Inc. and the appropriate corrective measures recommended for inclusion in the design during the preparation of the final plans. CONCLUSIONS AND RECOMMENDATIONS GENERAL We conclude that development of the property as planned is feasible providing that maintenance of the WSDOT drain systems to the level required to maintain or improve present performance is accomplished and that the recommended near - surface drainage measures are accomplished as subsequently discussed on pages 22 and 23. Development of the site will be difficult due to the marginal stability and saturation of the near - surface soils. Close coordination between the earthwork contractor and the engineer will be required to see that our recommendations are diligently followed, as subsequently discussed on page 22. There are two principal mechanisms of slope instability which could affect the property. These include deep - seated sliding in a zone of soil.. from 30 to 50 feet below the surface and surficial sliding in the upper unit of soil, generally extending to a depth of about 10 to 12 feet below the present ground surface. The potential for movement of the hillside in the deeper zone of soils is largely controlled by the continued satisfactory performance of the vertical well /horizontal drain system which was installed during construction of Interstate Highway 5. It is also controlled to a lesser degree by the "Original Test Drains" which were installed south of the vertical well /hori- zontal drain system. From our review of available information, it appears that the overall site stability in the approximately 20 years since these drains have been constructed has been good and that the drainage system continues to be generally effective in preventing deep- seated movements. It is of prime importance, however, that both of the WSDOT drain systems remain fully operational. If the drainage systems should deteriorate so that artesian pressures can again increase beneath the hillside, the risk of deep- seated and extensive earth movements can be expected to significantly increase. 16 GAIINIEVneers The second mechanism of shallow- seated movements is largely affected by surface runoff and near - surface infiltration of rainfall and runoff from higher ground. Based on the approximately 200 - foot -long scarp that was observed in 1982 and considered to be indicative of recent movement, it is evident that this potential for surficial movements is still relatively high in the southern portion of the property. We recommend that surface and near - surface drainage on the site be improved by constructing an interceptor ditch along the westerly limits of the property adjacent to Slade Way, together with installation of various drainage facilities in connection with site grading and building construction which are discussed subsequently. The piezometers and slope indicator which have been installed as a part of this investigation form the basic components of an instrumentation program to monitor long -term behavior of the property. We recommend that this instrumentation program be expanded prior to construction. Additional slope inclinometers and piezometers should be installed at locations where they can be protected and remain functional, both during and following construction. A series of hubs should be installed above areas where cuts are planned. The hubs should be initialized (surveyed in) immediately and monitored on a regular basis thereafter. The system of piezometers and the inclinometer currently in place should also be maintained and monitored on a regular basis. Some of the new piezometers may have to be located to replace existing piezometers which may be lost in construction activities. A long -term monitoring program to be accomplished under the direction of (or by) our firm is recommended. We consider such a program essential to detect any changes in effectiveness of the WSDOT and on -site drainage systems so that early remedial action can be taken if needed. The extent of the recommended instrumentation program is described in a subsequent section. Earthwork on this property will be very difficult. We recommend that site grading be undertaken during the late summer -early fall months when the least amount of rainfall can be expected and surface runoff and seepage in the upper soil units should be diminished. Depending upon the overall construction schedule for the project, it may not be possible to accomplish all earthwork and drainage- related activities as well as foundation construction 17 Geo o Engineers in a single dry season. Therefore, we strongly recommend that construction activities be scheduled so that site grading, drainage installation and surface stabilization, if not final paving, are completed in any given area within a single construction season. Construction should also be phased, as described subsequently, to minimize the impact in any one area. No area should be left partially graded or without proper surface drainage, as this may endanger the near - surface stability of that portion of the site if left through the wet seasons. Several of the planned structures are shown located above the existing sewer (see Figure 1). We understand that the sewer alignment may be changed so that it no longer is located below the structures. However, special foundation preparation procedures, as described on page 25, will be necessary along the sewer alignment to provide uniform bearing support for the structures. A major drainage way intersects the site in an east -west direction through the center of the site. It is important to maintain provisions for drainage along this gully alignment. Accordingly, we recommend that a French drain be installed along-the base of the gully as shown in Figure 1 before any filling is accomplished. EVALUATION OF 1-5 DRAIN SYSTEM The operational life of horizontal drains is not well known. Depending on the soil type into which the drain is installed, the installation method and other factors, drains may operate satisfactorily for many years. However, drains are also known to silt up or clog due to corrosion or algae and bacterial growths within the slotted sections of pipe. This can result in major, if not total, loss of operating effectiveness after a few years. There appear to be no data available to assess periodic changes in performance of the WSDOT drain systems over the last few years. However, there are records of the water levels during the period December 1966 to June 1968 for several piezometers located immediately east of the site. There are also records of our piezometers from November 1983 through the present, and recent records of the water levels in three Shannon & Wilson piezometers 18 • Geoki Engineers • and in the WSDOT wells (see Tables B -1 through B -3). Although the data are seasonal and precipitation varies on an annual basis, we believe that there is a sufficient data base on which to evaluate the effectiveness and degradation of the WSDOT drainage system. The locations of the piezometers for which data are available during the period December 1966 to June 1968 are shown in Figure 2. The piezometric elevations before and after drain installation during this period as well as the March 1985 readings are tabulated below: PIEZOMETRIC ELEVATIONS (FEET) IN SHANNON & WILSON PIEZOM TERS PRE AND POST I -5 DRAIN SYSTEM INSTALLATION Pre Drain Post Drain Piezo- Tip Water Water. Elevation meter Elevation Elevation Dec. 66 Oct. 67 June 68 March 85 1A 85 155 101 92 90 93 1B 100 115 109 97 100 111 19 52 149 111 111 122 N/L 232 49 72 65 60 77 N/L 1 80 162 103 102 110 139 2 86 153 130 122 123 N/L 3A 90 137 105 99 120 N/L N/L - Not able to be located. The tabulated data indicate that, with the exception of Piezometer 232, the piezometric surface was lowered between 15 and 65 feet approximately 3 years after installation. Since that time (June 1968) to the present, the water levels in the three Shannon & Wilson piezometers which we were able to locate indicate a rise of 3, 11 and 29 feet in Piezometers 1A, 1B, and 1, respectively. This indicates some degradation in the drain system; however, it may be related in part to the fact that the drains have not yet been cleaned out by WSDOT in 1985 (as of April). A similar comparison may be made of the water levels in Borings DM -1 and DM -3 from the Dames & Moore June 1961 report and Borings D and G in this study just inside the east property line of the site. This comparison is based on water levels at the time of the slide and at the present (March 19 Geot1,4, Engineers 1485) time. Borings DM -1 and DM -3 both indicated artesian conditions shortly after boring completion. Borings D and G indicate water levels approximately 56 and 77 feet below the surface, which represents a substantial reduction in water level in this area. Finally, a comparison may be made between the existing water levels in the vertical wells and the elevations at which the horizontal drains intersect the wells. If the system is operating effectively, the water levels in the wells should be 1 to 2 feet higher (to account for head loss in the horizontal drain) than the intercept elevations. Comparison of the data in Tables B -3 and B -4 in Appendix B indicates that only a few wells, 19 and 22, 23 and 24, are operating effectively. The water levels in the other wells are generally on the order of 20 feet higher, and Wells 1, 2 and 3 up to 70 feet higher than the levels of the horizontal drains at the wells. The excess head in the wells may indicate clogging of the drains (increased head required to obtain flow), or it may simply indicate total clogging of the horizontal drains and reduced flow by alternate paths. In addition, Wells 1, 2 and 3 are not consistent with Wells 4 and 5, and Shannon & Wilson Piezometers 1, 1A and 1B. It appears that, with the exception of the four wells noted, all of the horizontal drains and /or vertical wells are blocked to some degree. At this time (April 1985), it appears that the WSDOT drains have not been cleaned out for sometime, based on the vegetative growth at the outlets. It is likely that maintenance of the drain system will affect the water levels in the wells and thus influence the conclusions to be drawn from the existing available data. However, in spite of the indicated reduced performance of the WSDOT drain system, the water levels at the site are still significantly below the levels that existed at the time of the slide and the system is, in our opinion, still effective in maintaining the water level in Unit C low enough for adequate (F.S. =1.6) deep- seated stability of the hillside. However, we believe that the stability of the project site is primarily dependent on the continued effective operation of the WSDOT drain system. It is improbable, in our opinion, that the water levels at the site will rise to critical levels in a short period of time (that is, in days or weeks) but, rather, over a period of months. With monitoring 20 Geoff Engineers at regular intervals, changes in water levels can be detected and appropriate remedial measures may be implemented. The multiple well groups and horizontal drains provide a redundancy to the system. Also, some of the flow appears to have found other paths, possibly along the outsides of some drains, as evidenced by the flow through the panels at the retaining wall. We believe that it is essential that WSDOT expend effort to flush the horizontal drains and restore the effectiveness of the wells. If nothing is done, the drain system will continue to deteriorate, probably accelerating with time; however, if the drains are flushed and the wells cleaned and redeveloped if necessary, the system should continue to be effective for many years. Given the importance of the WSDOT drain systems on the stability of the project site, we recommend that the following repair work and maintenance procedures be implemented by WSDOT as soon as possible. o Clean out and flush the horizontal drains. o Clean out, flush and develop, if necessary, the 24 vertical wells. o Extract the pumps after flushing. (It is likely the pumps are silted in and may not be able to be extracted without flushing.) o Sound the depths of the wells. o Secure the top plates on the wells to prevent extraneous matter from being thrown into the wells. o Repair the "original test drain" system. o Locate and document the manifold outlets for the original test drains. o Monitor the flows from both systems of horizontal drains, as well as the piezometer levels, as discussed in the section on "Monitoring." SITE DEVELOPMENT The sequence of operations required to develop the site is critical to the successful completion of the project. In view of this condition, we have developed a general sequence for site development with regard to installation of instrumentation, drainage, site clearing and grading, and construction. Only minor deviations should be permitted from this sequence and then only with the approval of the engineer. 21 GeoK v Engineers The recommended site development sequence is as follows: 1. Install additional instrumentation at least two months in advance of construction, and preferably as soon as possible, to establish the preconstruction data base. (See section on Instrumentation and Monitoring for details.) Monitor instrumentation on a regular basis, to be specified at the time of installation, before, during and after construction. 2. Construct interceptor trench along west property line (see later details in this section), install temporary drainage ditches in construction -free upslope areas, and install temporary erosion control measures to pickup concentrated surface water flow, locate and tightline appropriate on -site horizontal drains. 3. Establish access road, accomplish general site clearing, install gully French drain and accomplish general site grading. 4. Perform individual structure grading on a phased basis. Alternate building areas should be graded and with the number of sites prepared limited to the number for which foundation, wall construction and backfilling can be completed during the dry season. The approximate location of the interceptor trench is shown on Figure 1. The trench should be approximately 2 feet wide and not less than 7 feet deep. It should preferably extend to the top of the gray silt which varied between 7 and 12 feet in the three closest borings. The trench should be lined with a monofilament filter fabric such as Mirafi 140N, with not less than 2 feet of overlap of adjacent sections of the fabric. A 6 -inch smooth -wall perforated pipe should be fully bedded in a well - graded sand or clean gravel at the bottom of the trench. The remaining trench backfill should be clean, free-draining sand and gravel. The filter fabric should cover the free - draining fill with a fabric overlap of 12 inches below the surface and be covered with the silty native soil. A detail of the interceptor trench is shown in Figure 5. The approximate location of the gully French drain is shown in Figure 1. The drain should be installed from the downstream end working up the existing gully. The gully should be cleaned out of all organic material and debris for a width of at least 8 feet and a 3- foot -thick blanket of graded sand 22 GeojEn Engineers and gravel filter placed in the gully. A smooth -wall, 8- inch - diameter perforated PVC pipe should be placed in a 12- inch -deep trench in the filter material and then covered with an additional 2 feet of the filter material. The top of the filter material should be at least 4 feet wide. The filter material should then be covered with filter fabric, as previously specified for the interceptor drain. Fill may then be placed in level lifts on either side of, and above, the filter material. We recommend that permanent French drains be installed along the upslope sides of all parking areas. These drains should be at least 5 feet below finished grades and should consist of perforated pipe fully bedded in a graded sand filter or in clean gravel which is, in turn, enclosed in a filter fabric envelope. The filter fabric should be installed with overlaps in the same manner as described above for the interceptor trench. The remaining trench backfill should consist of clean, free - draining sand and gravel. A similar drain should be installed in any wet areas to the west of the building units. Flow from these drains may be combined with flow from footing drains and downspouts for disposal in a storm drain system; however, the design of connecting pipes should be such to prevent backflow into sections of perforated pipe. We anticipate no impact on the WSDOT drain system from the proposed development if surface runoff is collected and routed off -site and surface water infiltration is minimized as recommended above. This conclusion is based on the fact that the WSDOT system services the lower aquifer and the barrier of lower permeability soils afforded by Unit B essentially precludes continuity between the upper and lower ground water regimes at the site. See Section on "GEOHYDROLOGICAL AND SURFACE WATER CONDITIONS" in this report. The ability to use the on -site soils for fill is expected to be limited. We anticipate that the soils in their natural state will be above optimum moisture for adequate compaction. In order to use these soils, drying will be necessary. Also, we recommend that only clean granular soils be used for fill behind retaining structures. While careful segregation of 23 q� Geo�o Engineers the natural soils during excavation may provide some suitable backfill, we anticipate that much of the backfill behind the walls and for any areas of structural fill will have to be imported. Stockpiling should be limited as much as practical on the site to minimize potential impacts on slope stability and erosion. As noted, most of the on -site soil to be excavated will be unsuitable for backfill and should be immediately removed from the site. The earthwork should be sequenced to limit the size of any stockpiles. If stockpiles are required, they should be placed at the north end of the site. The size and height of the stockpiles should be determined on a specific basis as construction progresses and in coordination with our field representative. We recommend that temporary cut slopes be made no steeper than approxi- mately 1- 1 /2H:1V (horizontal to vertical) and be limited to 15 feet in height. The stability of these cut slopes will be relatively low. Our analyses indicate that the factor of safety under static, drained conditions will be on the order of 1.2 to 1.3, assuming some short -term cohesion. Some sloughing or localized sliding should be anticipated, particularly where zones of seepage are encountered. When the excavations are made for the various buildings, we recommend that the construction be sequenced so that alternate building sites are excavated (for example, Sites 3, 5, 7, 9, etc.), retaining walls built and adequately braced, perimeter drainage installed, and backfill placed before beginning excavation for the intermediate buildings. Permanen(y; cut .; f41MM1sl 1r71'fiould b e` a tabl 4Lat no sWpe “han! H:1V Slopes should be seeded as soon as practical. Localized seeps which are not intercepted by the general drainage facilities may have to be drained and /or excavated and backfilled with gravel or crushed rock to resist erosion damage to slopes. STRUCTURAL FILLS AND PAVING All structural fill should be placed in relatively thin (8 to 10 inches) layers and uniformly compacted. Back�f =il gainst.: seta ning wallas. par-ticul5arly thoseJakii.n ith_e sit,r- acplures srh e overcompacted ; A compaction 6 24 Geo Engineers gad to `92` 'p ceht.'of. the tmaximum ry density, determined ;by,ASTMvp-°1.75Wshould be achieved. F;i11' beneathpaved;7a.r-eas or ,forming slopes "shout °dam b ce ompacte percent fi42TraTipi density. We understand that access roadways and parking areas will be paved with asphaltic concrete. Prior to placing base course material, we recommend that the exposed subgrade be thoroughly proofrolled. Any soft, loose or wet areas should be excavated and replaced with clean granular fill if the natural soils cannot be satisfactorily recompacted. Based on the existing surficial wet conditions, it should be expected that overexcavation and replacement of on -site soils with imported granular fill will be necessary over much of the roadway and the parking area. Overexcavation of 12 to 18 inches may be necessary for roadways and parking areas to establish a stable subgrade. All fill placed below subgrade level should be compacted to at least 92 percent of maximum dry density (ASTM D- 1557). A pavement section of 4 -1/2 inches of clean pit run subbase, 1 -1/2 inches of crushed rock base and 2 inches of asphaltic concrete should be used. The extent of overexcavation and replacement -of backfill along the existing sewer in areas to be occupied by buildings should be verified by examination during construction. As a worst case condition, the following may be necessary. Fill used to replace material excavated from the sewer line trenches should consist of clean granular soil. The existing backfill should be excavated from beneath the full building area and beyond for a distance of 4 feet on both sides to a depth of at least 5 feet below the bottom of the footing or to the top of the pipe, whichever is more shallow. The first foot of backfill over the pipe should be compacted to about 92 percent of maximum dry density and the remainder to 95 percent. RETAINING STRUCTURES Retaining structures will be required for all of the buildings based on present plans. The units will be stepped into the hillside so that each section of retaining wall will be no more than one story high. The setback between walls is expected to be 15 feet or more. In addition, retention of cut slopes and fill embankments will be required along portions of the parking areas and near Unit Nos. 1 and 2. 25 GeoN0 Engineers We recommend that lfate!al7pr.es. uses: on the 'basemen t wafiiibe determined using an equivalent fluid density of 35' ' p; ounds;,.,p:er_.yculii7a7f-oo (pcf) ,t- Ames he: ght of::=thet_wa1:1 '=in feet This value applies only if clean, lightly compacted granular backfill is used against the walls and.if a perforated drain is installed along the base of the wall to prevent the buildup of hydrostatic pressure. ThIis value - also applies^ only`where7the; ground ^_surface behind the;. wal1717s level .f, "o —r a d:iatance equal to .the height_: of;<the wall. If a sloping ground surface exists closer to the wall, this value may have to be increased. Rret 'i ili tructures" along the parking area and elsewhere out d , of,thpbuldng could consist of gabion basket walls, reinforced earth structures, or conventional poured concrete walls. We recommend against the use of rockeries except possibly for protection of low (less than 5 feet) cuts into natural soils. Rockeries should not be used to retain fill embankments. Where backfill behind the walls is level, lateral pressures may be determined using an equivalent fluid density of 35".pdfjtimes the height of the wall in feet. Where the surface slopes upward behind the wall, an increased lateral pressure must be used. If-1,a backslope;of 3Ha1g exists, wee- r -ecomm ne eraf 4p,re using an e 1riva- lent" f,lu d density of 60:= pcf- times_ the- Height of the wall' n feet? We should review design criteria for other backslope configurations. Drainage of the backfill as well as cut slopes behind these retaining structures is critical to their stability. The lateral pressure design criteria given above is based on drained conditions. For solid structures, such as a poured wall, a zone of clean backfill and a perforated drain should be installed. If gabion basket walls are used, we recommend that filter fabric be placed beneath and behind the baskets to prevent the retained soils from washing into the relatively open work gabion rock. A perforated base drain located immediately behind the baskets is also recommended for gabion installations. Resistance to lateral loads on retaining structures may be developed by passe viT s`suiTa and baseYfriction: We recommend that passive —press s be determined using an equivalent fluid density of-200A3outail per cubic 26 Geoff O Engineers foot. &a`se fr;i;ctional' resiAganrcer.,can be determined using a factor oETCA7 times the vertical downward component of long -term loading. These values incorporate a Wa tx'"rof'sofOrdfaliout X31: FOUNDATION DESIGN We recommend that the lowest floor grade of each structure be established at an elevation such that a shallow foundation system will bear directly on below h layer. �� . omind ai�c�cl1a u n st.r c u es briationof c t and may benecess r y to overexcavate and replace some of the native materials if soft, wet conditions are encountered during construction. This will probably occur all along the sewer line, as 'previously discussed. Ouerexcavation /repYacemeif will sat facto:0:ADrov dti�'ngJ;�>that any�fill�whicfi- is placed7,doe_ "s not extend above the. :ground- surface elevation We suggest the use> of a, foundationjt system„ cons stiing;ofra; thickene'dl slab system-that will'provide -more rigidity wand resistance to slight_ d ifleren• tial: movementsacross,:a7structure7 than that wtichwouitL.be', provided by;_ co nai'n:uous•=wa_ll-.footings- and a slab .on s ralde:7system. -..The foundation system should consist of thickened edges around the perimeter of the slab and thickened sections beneath bearing walls within the buildings. The thickened',slab system " should have:.continuous re nforcing•_ consisting .of,1r.einfor.cing...:bar; rather: - than'7steel7mesh'. The thickened edge sections should extend at least 18 inches below lowest adjacent finished grade and_should have a base width of at least 18 inches. The thickened edge portion of this foundation system may be proportioned using a bearing vaglueot? 2,q�0,0 pounds per square foot. This value applies to the total of all design loads including wind or seismic, but excluding the weight of the footing and any overlying backfill. Care must be taken in preparing the subgrade for the thickened slab foundation system to avoid disturbance to the bearing materials. Any seepage which is encountered should be collected and diverted from the building area. Theprepared b aringsurfaces >3- ``should' be rexamiriedb �oneof -our 's•taf ._. Y to determine that suitable preparation has been accomplished. It may be necessary to move and replace soft, wet or otherwise disturbed soils and to install localized drainage facilities to handle any seepage within the building area proper. A ny sofa soil should .bereplacedz,with :"clean,granular 27 Geo6o Engineers ftii�lzl comp`a'c edtos 95.`percent:!of .the -maxi mum ry der-is-WTI We recommend that the bearing surface be protected from disturbance during reinforcing steel placement and concrete pouring by placing a n•c'h= ahi2ck -laye,r 7of d, o sand': and ;gravel o panted too a iii deratelyl dense sta e7 Over compaction should be avoided to prevent pumping if the subgrade soils are wet. .We recommend that foundation drains be installed along the outside of the thickened edge sections of the foundation system. These drains, together with the drains for the retaining wall sections of the buildings, should be connected to tight drain lines along the east property lines so that flow can be. conducted off -site for disposal in a means which will not adversely affect the stability either of this site or the hillside to the east. Setttlementt of the foundation system designed and installed as recommended above is expected to be relatively small, probably on the order ofT141 s of:ir inc1 Some differential settlement may ;occuracros_sruni s because of the ' �fferen esrof eliefof overburden pressure r;e'szultini f o tahe '°'vary g;dept;hs- o -f excavation to establish lowest floor grade levels. INSTRUMENTATION AND MONITORING The purpose of the instrumentation program and long -term monitoring at the site is to establish base line data for the performance of the horizontal drain system and, hence, to set up an early warning system if the water levels in the slope start to rise. The instrumentation program which we envision as being appropriate includes piezometers located in areas where they will not be damaged by site grading and construction activities, a network of inclinometers to monitor any hillside movement, survey stakes on slopes which are regraded or which have cuts made at the toe of the slope, and benchmarks established on building foundations as they are con- structed. We recommend installation of at least 6 additional inclinometers, 4 along the easterly boundary of the project site and 2 along the upper portion of the site, one to the north and one to the south of Inclinometer F. These inclinometers will be installed to function as piezometers as well. 28 Geoo Engineers The piezometers and inclinometers should be installed at least two months prior to, and preferably as soon as possible, to start obtaining baseline data. The number of additional piezometers installed may vary, depending on how many of the existing ones can be saved. It appears probable that 4 or 5 of the existing piezometers will be lost (D, G, H, J, and K). We recommend installation of 6 to 10 shallow piezometers (i.e., to depths of approximately 20 to 25 feet each) to monitor water levels in the upper soil strata and 3 or 4 additional deep piezometers to supplement the piezometric data developed from the inclinometers. The shallow piezometers will monitor the effectiveness of -the westerly interceptor drain and other site drainage ,facilities. In addition to the long -term instrumentation, slope monitoring stakes should be installed in areas where grading involves cuts into the near - surface soils. These should consist of one or more rows of stakes on 20- to 40 -foot centers from which elevation and alignment records can be maintained to determine whether or not any movements occur in.the surficial soils. If any movements are detected, remedial measures will be able to be undertaken promptly. As building foundations are placed, permanent reference points should be established at least on the four corners of each building and the elevations recorded. Future elevation readings of these points will then provide a basis for determining any elevation changes which may occur due to foundation settlements or hillside movements. If hillside movements should occur, they would also be reflected in the inclinometer readings. We recommend that the monitoring program initially require that inclino- meters and piezometers be monitored monthly during construction, bi- monthly between construction seasons and twice a year, in February and August, after completion of the project. More frequent monitoring may be required, depending on the weather. Slope monitoring stakes should be surveyed on an every- other -day basis while grading activities are underway in the immediate area and monthly during periods of construction until project completion. It is anticipated that slope stake systems will be lost in final landscaping. 29 Gent* Engineers Benchmarks on building foundations should be initialized as soon as they are set and read once when each building unit is about 50 percent complete, once upon completion, and annually thereafter. A detailed action plan should be prepared so that it can be promptly implemented in the event of significant changes in water levels or indications of slope movement. The plan should include trigger levels for the inclinometers and piezometers, and specific actions by responsible parties should be established. We recommend that an overall rise in water level of ten (10) feet in the lower aquifer (Unit C), as measured by the on -site piezometers, be taken as a "trigger" level for remedial action. Other trigger levels related to the WSDOT- -drain systems should be established once they have been cleaned out and are working properly. Trigger levels for the inclinometers should be based on an increase in displacement of more than 0.2 inches per year. The action plan should consist of the following: 1. Notifying our firm immediately. 2. Analysis of the data by our firm to establish the probable cause of the changed conditions at the site. 3. Developing recommendations by our firm for obtaining additional information if necessary and to implement the necessary remedial measures. These recommendations may include: o Obtaining additional information such as surveying the settlement hubs at the site. o Increasing the monitoring frequency. o Maintenance or restoration of the on -site drainage or WSDOT drain systems. o Installation of new horizontal drains on or off site (WSDOT right -of -way). o Pumping the vertical wells in the WSDOT system. o Implementing localized slope stabilization measures. It should be kept in mind that modifications to the number, locations, and, possibly, types of instrumentation as well as modification in the frequency of monitoring may be appropriate as project construction progresses. 30 Geo01 Engineers For this reason, it is imperative that GeoEngineers have a continuing parti- cipation on the project to coordinate installation of the instrumentation, to recommend changed locations or additional points, to monitor the instrumen- tation, and to interpret the data and advise on the performance of the hillside and recommend what, if any, remedial measures may be appropriate. USE OF THIS REPORT We have prepared this report for use by Dr. H.M. Allenbach and members of the design team. This report should be provided to prospective contractors for their bidding or estimating purposes. Our report, conclusions and interpretations should not be construed as a warranty of the subsurface conditions. As noted previously, we have used data developed by our firm as well as by others at widely spaced locations. If there are changes in the loads, grades, location, configuration or type of construction planned from that which we have been provided, the conclusions and recommendations presented may not be applicable. If design changes are made, we request that we be given the opportunity to review our conclusions and recommendations and to provide a written modification or verification. When the design has been completed, we recommend that the appropriate construction drawings and specifications be reviewed by our firm to see that our recommendations have been interpreted and implemented as intended. The earthwork and site preparation activities are of critical .importance to the success of this project. . GeoEngineers, Inc. must be involved in the construction monitoring and field to see that our recommendations are properly interpreted and implemented. If we are not involved in the con- struction phase of the project, we disclaim any liability for the manner in which the construction is accomplished or the results thereafter. The scope of our services does not include services related to construction safety precautions and our recommendations are not intended to direct the contractor's methods, techniques, sequences or procedures, except as specifi- cally described in our report for consideration in design. There are probable variations in subsurface conditions between the explorations and also with time. A contingency for unanticipated conditions should be included in the budget and schedule. The construction monitoring, 31 Geo40 Engineers testing and consultation by our firm will provide the opportunity to confirm that the conditions encountered are consistent with those indicated by the explorations, to provide recommendations for design changes should the conditions revealed during the work differ from those anticipated, and to evaluate whether or not earthwork and foundation installation activities comply with contract plans and specifications. Within the limitations of scope, schedule and budget, our services have been executed in accordance with generally accepted practices in this area at the time the report was prepared. No other warranty, express or implied, should be understood. The conclusions and recommendations in this report should be applied in their entirety. If there are any questions concerning this report or if we can provide additional services, please call. GMD:JKT:da File No. 523 -02 April 25, 1985 Respectfully submitted, GeoEngineers, Inc. Wail/ n M. Denby Se Engineer 32 Tuttle incipal FIGURE 1 N L� PROPOSED INTERCEPTOR TRENCH PROPOSED FRENCH DRAIN \ A -�L PARKING �U �oARKING 13 14 15 r r REFEf2ENCE: DRAWING ENTITLED "VALLEY VIEW ESTATES" BY WILSEY & HAM INC, DATED 5/3/82 r 0 12 "DIAMETER DUCTILE IRON SEWER LINE NOTE: PROPOSED INTERCEPTOR TRENCH TO BE LOCATED IN THE FIELD. TRENCH TO BE ALIGNED ALONG CONTOUR AND DRAIN FROM NORTH TO SOUTH. PROPOSED FRENCH DRAIN TO BE LOCATED IN FIELD IN EXISTING DRAINAGE GULLY. EXPLANATION: --D BORING LOCATION AND LETTER DESIGNATION DM -1 ® DAMES & MOORE INVESTIGATION 1961 0 80 160 SCALE IN FEET GeoEngineers Inc. SITE PLAN FIGURE 2 rA 4 .;a ate 0 fApproximat ';., 'of Slide • 4\' ' • ' \ - eExt::41 — 20 -61- 100 200 300 � � I Scale In Feet Reference: Drawing entitled "Plan of Completed Remedial Measures" by Shannon & Wilson dated March 31, 1966. Legend: Horizontal Drains (existing) o Original Test Drains 0---Recommended Drain (Grade: 1 -3 %) Cylinder Pile Wall AP'' Existing or Proposed Right of Way 4- Additional Vertical Drains (6 -9 in. dia.) • Large Diameter (5') Deep Well 4:1 Final Excavated Slope (horizontal:vertical) • Piezometer Installed During 1966 Investigation GeoEngineers Inc. 1 HORIZONTAL DRAIN AND WELL SYSTEM Reference: Drawing entitled "Plan of Slide Area with Reconnaissance Data and Proposed Drainage" by Shannon & Wilson, dated June, 1964. Legend: -a o FIGURE 3 Marsh Areas with Surface Seepage Seepage Zones Horizontal Drains Installed by Others 0.4 gpm Flow Measured May 12, 1964 S? Subdrains to be Installed Under 67 Existing Contract ® S1ope,Indicator Installed by Shannon & • Wilson, Inc. in June, 1964 ® Drill Hole Made by Shannon & Wilson in May -June, 1964 e Observation Well Installed by the State N Indicator Installed by the State Boring Made by Dames & Moore, April, 1961 0 50 100 150 I 1 1 I Scale In Feet GeoEngineers Inc. EXISTING ON SITE HORIZONTAL DRAIN LAYOUT FIGURE 4 I— w w u_ z ELEVATION A 240 — 200— 160— 120— 80— W Z J 1- s„ cY w cy 0 z ESTIMATED PERCHED WATER TABLE WATER TABLE IN UNIT C 0 0 i LL O z m� J O /i m ;—° /m ilirM■ 11M1 Iml‘-- ,iitALILII r . \� UNIT B ai • UNIT C LL_L_l� UNIT A _GRAY SILTY SAND AND SANDY SILT CCOLLUVIUM AND SLOPE DEBRIS) UNIT B GRAY SILT WITH INTERBEDDED WET SILTY SAND TO SAND LAYERS;' SLICKENSIDES TOWARDS BASE OF UNIT. UNIT C GRAY SAND AND GRAVEL INTERBEDDED WITH SILT LAYERS; WET. w z J PROPERTY —240 —200 —160 —120 —80 ELEVATION IN FEET HORIZONTAL SCALE: 1" = 40' DATUM: CITY OF TUKWILA GeoEngineers Inc. CROSS SECTION A —A1 WELL GRADED SAND OR CLEAN GRAVEL BACKFILL NON -WOVEN FILTER FABRIC MINIMUM WIDTH =2' 6" PERFORATED PIPE MINIMUM DEPTH =7' GeoEngineers Inc. SCHEMATIC OF PROPOSED INTERCEPTOR DITCH APPENDIX A FIELD EXPLORATIONS AND LABORATORY TESTING FIELD EXPLORATIONS Subsurface soil and ground water conditions at the site were explored by drilling 8 borings at the locations shown on the Site Plan, Figure 1. The borings were generally terminated in the waterbearing sand and gravel layer. Total lineal footage was 572 feet. The borings were drilled using a truck - mounted, 4 -inch inside diameter, hollow -stem auger drill rig. Observation wells consisting of 1/2 -inch PVC pipe with a slotted tip were installed in all borings, except Boring F, after drilling was completed. A double installation was used in Boring J where a well tip was installed at the bottom of the hole and at the contact with the silt at 20 feet depth. A slope inclinometer casing was installed in boring F in order to permit measurement of any future movements in the slope. A geotechnical engineer from our staff was present during the explora- tions. Our representative assisted in locating the borings, obtained repre- sentative soil samples, examined and classified the soils encountered, observed ground water conditions and maintained a detailed log of each exploration. The soils were classified in accordance with the Unified Soil Classification 'System which is described on Figure A -1. The logs of the explorations are presented on Figures A -2 through A -17. Relatively undisturbed soil samples were obtained from the borings using a heavy -duty sampler with 2 -1/2 -inch brass liner rings. The sampler was driven using a 250 -pound hammer falling a distance of 30 inches. The driving resistance for one foot of penetration is noted on the logs adjacent to the sample notations. All samples were sealed in containers to limit moisture loss, labeled and taken to our laboratory for further examination and testing. LABORATORY TESTING Selected samples were tested to determine the field moisture and density and strength characteristics. The moisture - density data are presented on the logs of the explorations next to the appropriate sample notations on Figures A -2 through A -18. A - 1 FIGURE A -1 { BORING LOG AND SAMPLE DATA KEY DRIVEN SAMPLES BLOWS REQUIRED TO DRIVE SAMPLER ONE FOOT OR MOISTURE CONTENT 28 11.2% 111 $ DRY DENSITY ® IN PCF ❑ INDICATED PENETRATION USING POUND HAMMER FALLING INCHES "P" INDICATES SAMPLER PUSHED WITH WEIGHT OF HAMMER INDICATES LOCATION OF UNDISTURBED SAMPLE INDICATES LOCATION OF DISTURBED SAMPLE INDICATES LOCATION OF SAMPLING ATTEMPT WITH NO RECOVERY GRAPHIC LOG OTHER TYPES OF SAMPLES SM LETTER SYMBOL SOIL TYPE DISTINCT CONTACT BETWEEN SOIL STRATA GRADUAL CHANGE BETWEEN SOIL STRATA IINDICATES LOCATION OF THIN WALL, PITCHER, OR OTHER TYPES OF SAMPLES (SEE TEXT) / BOTTOM OF BORING UNIFIED SOIL CLASSIFICATION SYSTEM MAJOR DIVISIONS LETTER SYMBOL DESCRIPTIONS COARSE GRAINED SOILS NORE-THAW50% OF MATERIAL IS L 8 t 1HAN W. • 200 SIEVE SIZE GRAVEL AND GRAVELLY SOILS KRE THAN 50% IT a �e>• A - DN C. 4 SIEVE CLEAN GRAVELS (LITTLE DR NO FINES) GW WELL-GRDES.GLITVTLLS. GRAVEL-SAND U GP POORLY�,R/IDED'.GRAVELS:: GRAVEL- SAN) MIXTURES.. LITTLE OR ND FINES GRAVELS... WITH FINES (APPRECIABLE AMOUNT CF FINES) GM SILTY GRAVELS;; GRAVEL -SAND -SILT MIXTURES. ,. _ GC CLAYEY GRAVELS. GRAVEL- SAND -SILT MIXTURES SAND AND SANDY SOILS TORE THAN 50% OF CCNRSE FRAC- TIEN PASSING CLEAN SANDS (LITTLE DR W FINES) SW WELL GRADED SAWS. GRAVELLY somas. LITTLE OR NO FINES SP POORLY-GRADED SAWS. GRAVELLY SAGS... LITTLE OR NO FINES SANDS WITH FINES (APPRECIABLE AMOUNT OF FINES) SM SC SILTY SANDS. SAO -SILT MIXTURES ( CLAYEY SAWS. SAM -CLAY MIXTURES W. 4 SIEVE FINE GRAINED SOILS MORE THAN 50% CF MATERIAL INJ. 200 SIEVE SIZE SILTS AND CLAYS LIQUID LIMIT LESS THAN 50 ML INORGANIC SILTS. AN) VERY FINE SANDS. ROCK FLOUR. SILTY OR CLAYEY FINE SAWS DR CLAYEY SILTS WITH SLIGHT PLASTICITY CL INORGANIC CLAYS OF LOW TO NEDIUM PLASTICITY. GRAVELLY CLAYS. SANDY CLAYS. SILTY CLAYS. LEA( CLAYS OL ORGANIC SILTS ANC ORGANIC SILTY CLAYS OF LOW PLASTICITY SILTS AND CLAYS LIQUID LIMIT GREATER THAN 50 MH INORGANIC SILTS. MICACEOUS OR DIATO- MACEOUS FINE SAND OR SILTY SOILS CH INORGANIC CLAYS OF HIGH PLASTICITY FAT CLAYS OH ORGANIC CLAYS or MEDIUM TD HIGH PLASTICITY. ORGANIC SILTS HIGHLY ORGANIC SOILS PT PEAT. HUMUS. SWAP SOILS WITH NIGH ORGANIC CONTENTS NOTE. DUAL SYMBOLS INDICATE BORDERLINE SOIL CLASSIFICATION GeoEngineers Inc. UNIFIED ND I LYCLASS I F I CAT IONASYSTEM FIGURE A -2 0 BORING C ELEVATION: 237.1 FEET GRAPHIC TEST DATA LOG DATUM: CITY OF TUKWILA DESCRIPTION z 5 23.8% 99.1 II 9 31.9% 91.5 II w H 29. A 31.2% 91.711 15 33 28.3% 94.2 ®. 20 32 24.5% 100.9 11 25" 53 24.6% 100.5 30— 54 6.9% 98.311 35 — 53 o" 9.6% 122.8 40 S M ML ML SP BROWN SILTY SAND ;dITH GRAVEL (STIFF, MOIST) GRAY SANDY SILT WITH RUST STAINS (STIFF, MOIST) GRAY . SILT WITH WET FINE SANDY SILT INTERBEDDED (STIFF, MOIST) SLICKENSIDES SLICKENSIDES FINE SANDY SILT LENSES• SLICKENSIDES GRAY FINE TO MEDIUM SAND (MEDIUM DENSE TO TO DENSE, MOIST) HIT GRAVEL AT 38 FEET FOR 2 FEET, THEN SANDY, THEN BACK INTO GRAVEL "SEE KEY FOR EXPLANATION OF SYMBOLS GeoEngineers Inc. LOG OF EXPLORATION 40 BORING C (CONTINUED) GRAPHIC TEST DATA LOG DESCRIPTION 45 - w50- z H 55 - 60- 65" 70- 75- 51 6" 14.3% 116.1 93 34.9% 82.7 50 4" 26.0% 99.011 50 5" 26.6% 98.71. 50 5" 16.1% 16.1% 119.2 11 89 6" 4.0 159.8 ■ 7.1% 60 6" ML SM SM ML SM ML GM GRAY GRAVELLY SANDY SILT TO SILTY SAND WITH WET FINE TO MEDIUM SAND LENSES (STIFF TO DENSE, MOIST) GRAY FINE TO MEDIUM SAND WITH SOME SILT, ORGANIC FRAGMENTS AND MICA (DENSE, MOIST TO WET) SHOE CONTAINED WOOD GRAY FINE SANDY SILT (STIFF, MOIST TO WET) GRAY GRAVELLY SILT WITH FINE TO MEDIUM SAND LENSES AND OCCASIONAL ORGANIC FRAGMENTS (STIFF TO VERY STIFF, HOIST) GRAVEL AT 64 FEET BORING COMPLETED AT 73'z.FEET ON '10/20/83 PIEZOMETER INSTALLED AT 73-. FEET ON 10/20/83 GROUND WATER LEVEL AT 64 FEET DURING.DRILLING *SEE KEY FOR EXPLANATION OF SYMBOLS GeoEngineers Inc. LOG OF EXPLORATION FIGURE 'A -4 0 5 BORING D ELEVATION: 178.8 FEET *GRAPHIC *TEST DATA LOG DESCRIPTION H 15- 20- 25- 30- 35- 40-- 9 26.6% 91.111 14 30.9% 88.81 36 29.6% 93.111 19 23.5% 100.91: 32 18.8% 110.61• 32 19.7% 110.91. 50 5t1 9.6% 50 2" 6.4% 142.4® ML ML ML SM GP BROWN AND GRAY SILT WITH ORGANIC FRAGMENTS AND ROOTS (STIFF, MOIST TO WET) (FILL ?) GRAY SILT WITH SOME RUST STAINS (STIFF, MOIST) LAMINATIONS DIPPING' AT 20 °,000AS.IONAL CALCIUM CARBONATE CONCRETION . GRAY SILT WITH POCKETS.OF GRAY FINE SAND (STIFF, MOIST) OCCASIONAL GRAVEL WITH FINE SANDY SILT LENSES SLICKENSIDES GRAY SANDY GRAVEL (DENSE, WET) *SEE KEY FOR EXPLANATION OF SYMBOLS GeoEngineers Inc. LOG, OF EXPLORATION 40 BORING D (CONTINUED) *GRAPHIC *TEST DATA LOG DESCRIPTION FIGURE A -5 45- 78 6" 7.3% 139.2ED 50 311 GP 11.5% Eg w50- z 50 GP GRAY SANDY GRAVEL WITH SOME SILT (DENSE, WET) =' 4" GM °w 10.6% 130.80 55 - 60- 100 GM GRAY SILTY SANDY GRAVEL (DENSE, WET) 21" 19.7% ® 7 FEET OF HEAVE AT 571 FEET BORING COMPLETED AT 58'-1 FEET ON 10/19/83 PIEZOMETER INSTALLED AT 582 FEET ON 10/19/83 *SEE KEY FOR EXPLANATION OF SYMBOLS GeoEngineers Inc. LOG OF EXPLORATION FIGURE A -6 0 5 20- 25- 30- 35- 40- BORING F ELEVATION: 237.0 FEET *GRAPHIC *TEST DATA LOG SM 5 43.5% 70.911 7 35.0% 86.211 DESCRIPTION BROWN- BLACK -GRAY SILTY SAND WITH ORGANICS (MEDIUM DENSE, MOIST TO WET) (FILL) GRAY SAND WITH MICA (MEDIUM DENSE, MOIST TO WET) 6 .ML GRAY FINE SANDY SILT (SOFT, WET) 27.4% 96.111 14 27.0% 97.911 12 30.3% 93.811 ML GRAY SILT WITH A TRACE OF CLAY WITH SLICKENSIDES AND SOME WET FINE SANDY SILT LAYERS (MEDIUM STIFF, MOIST) ML GRAY SILT AND FINE SANDY SILT LENSES AND SLICKENSIDES (STIFF, DAMP) 35 30.6% 92.211 51 30.10 92.511 SLICKENSIDES 65 24.3% 101.911 ML GRAY FINE SANDY SILT WITH SLICKENSIDES (STIFF, DAMP) *SEE KEY FOR EXPLANATION OF SYMBOLS GeoEngineers Inc. LOG OF EXPLORATION DEPTH IN FEET 40 BORING F (CONTINUED) *GRAPHIC *TEST DATA LOG DESCRIPTION FIGURE A -7 45 - 50- 55- 60- 65 76 26.5% 97.311 34 20.6% 109.5 50 51 13.5% 122.65 ML SOME FINE SANDY SILT LENSES ML GRAY SILT INTERBEDDED WITH FINE TO MEDIUM SAND SP (STIFF TO DENSE, MOIST TO WET) INCREASING GRAVEL CONTENT WITH DEPTH 50 2" GM GRAY SANDY SILTY GRAVEL TO SANDY GRAVELLY SILT 9.1% 117.65 ML (DENSE TO VERY DENSE, MOIST TO WET) GM GRAY SANDY SILTY GRAVEL (VERY DENSE, MOIST TO WET) 50 13-71- 1 5 BORING COMPLETED AT 63 FEET 1 INCH. ON 10/21/83_ GROUND WATER LEVELS MEASURED AT 10.5 AND 53 FEET DURING DRILLING INCLINOMETER CASING INSTALLED AT DEPTH OF 63 FEET 1 INCH ON 10/21/83 *SEE KEY FOR EXPLANATION OF SYMBOLS GeoEngineers Inc. 1 LOG OF EXPLORATION FIGURE A -8 BORING G ELEVATION: 179.2 FEET *GRAPHIC *TEST DATA LOG DESCRIPTION 5 20" 25- 30- 35- 40" 20 11.2% 105.011 20 25.9% 98.711 15 32.0% 90.31 16 25.7% 99.81 8 35.0% 86.511 18 32.3% 90.811 31 28.7% 92.711 57 27.7% 95.911 SM SM BROWN GRAVELLY SILTY SAND WITH SOME COBBLES (MEDIUM DENSE TO DENSE, MOIST) BROWN AND GRAY RED - STAINED GRAVELLY SILTY SAND (MEDIUM DENSE, MOIST) ML GRAY SILT WITH FINE SANDY SILT LENSES (STIFF, MOIST) FINE SANDY SILT LENSES (MOIST TO WET) SLICKENSIDES DIPPING AT 45° FINE SAND LENSES GRADES TO VERY STIFF AND DAMP SLICKENSIDES SLICKENSIDES WITH FINE SANDY SILT LENSES *SEE KEY FOR EXPLANATION OF SYMBOLS GeoEngineers Inc. LOG OF EXPLORATION FIGURE A -9 40 *GRAPHIC *TEST DATA LOG BORING G (CONTINUED) DESCRIPTION 45- 32 25.1% 99.8 42 25.2% 100.311 21 Q 24.8% 101.111 55- 63 6" 24.0% 101.211 60- 86 6" 12.4% 125.3 65- 50 1" 13.7% 121.9N 70- 70 6" 26.3% 99.411 75 - 50 6" 25.3% 96.5 ■ 80 - ML ML SP SM GM SP HIT GRAVEL AT 45 FEET GRAY SILT WITH FINE SANDY SILT AND FINE TO MEDIUM SAND LENSES (STIFF, MOIST) SLICKENSIDE GRAY FINE TO MEDIUM SAND WITH GRAY SILT INTERBEDDED (MEDIUM DENSE, WET) INCREASING GRAVEL CONTENT GRAY SILTY. SANDY. GRAVEL (DENSE,.MOIST.TO. WET) 2 FEET HEAVE AT 67.5 FEET GRAY FINE TO MEDIUM SAND WITH SOME GRAVEL AND OCCASIONAL GRAY SILT LAYER (DENSE, WET) BORING COMPLETED AT 782 FEET ON 10/18/83 GROUND WATER LEVEL AT 491 FEET DURING DRILLING PIEZOMETER INSTALLED AT 78'- FEET *SEE KEY FOR EXPLANATION OF SYI"BOLS • GeoEngineers Inc. 1 LOG OF EXPLORATION 1-IGUKt A -lU 0 BORING L ELEVATION: 207.5 FEET *GRAPHIC *TEST DATA LOG DESCRIPTION 5- 18 9.80 122.51 6 35.4% 84.91 6 Q 33.4% 89.11 15- 8 26.1% 98.01. 20" 22 30.7% 92. 21 25- 34. 29.9% 93.41 30- 51 27.4% 97.01 35- 43 27.6% 96.411 40-- SM ML BROWN GRAVELLY SILTY SAND (MEDIUM DENSE, MOIST) GRAY SILT WITH REDDISH BROWN STAINS AND FINE SAND INTERBEDDED (SOFT, MOIST) 1 GRADES TO MEDIUM STIFF FRACTURES GRADES TO STIFF 1/8 INCH SAND LENS AT 282 FEET GRADES TO VERY STIFF, DAMP SL1CKENSIDE AT 37z FEET *SEE KEY FOR EXPLANATION OF SYMBOLS GeoEngineers Inc. 1 LOG OF EXPLORATION . FIGURE A -11 40 *GRAPHIC *TEST DATA LOG BORING L (CONTINUED) DESCRIPTION 73 22.3% 104.411 45 - 86 25.8% 98.411 = H 3 2 Q 23.5% 104.41. 55- 52 6," 13.5% 125.91 60- 65 ML SM ML SP _GM GRAY INTERBEDDED SILT AND FINE SAND (VERY STIFF, MOIST) FRACTURES AND SLICKENSIDES GRAY FINE SAND (LOOSE TO MEDIUM DENSE, WET) GRAY SANDY GRAVEL WITH A TRACE TO SOME SILT HEAVE AT 611 FEET BORING COMPLETED AT 63 FEET ON 10/14/83 GROUND WATER LEVEL ESTIMATED AT 49 FEET DURING DRILLING___ PIEZOMETER INSTALLED AT A DEPTH OF 63 FEET ON 10/14/83 *SEE KEY FOR EXPLANATION OF SYMBOLS GeoEngineers Inc. LOG OF EXPLORATION FIGURE A -12 DEPTH IN FEET 0 BORING H ELEVATION: 229.5 FEET *GRAPHIC *TEST DATA LOG DESCRIPTION 5- 10- 15- 20- 25- 30- 35- 40- 6 21 30.5% 90.811 24 30.2% 92.4 22 28.6% 95.21 0.9% 92.2Il 31 24 5.6% 100.411 29 26.2% 99.71 21 28.8% 95.411 SP -SP ML BROWN SILTY FINE SAND WITH GRAVEL (MEDIUM DENSE, MOIST) (FILL) TAN TO BROWN FINE SAND WITH RUST STAINS (LOOSE, MOIST) GRAY SILT WITH SAND LENSES (STIFF, MOIST) /WITH A TRACE OF CLAY *SEE KEY FOR EXPLANATION OF SYMBOLS GeoEngineers Inc. LOG OF EXPLORATION 1-I(7UK H-17 DEPTH IN FEET 40 45- 50- 55" 60- 65- *GRAPHIC *TEST DATA LOG 25 33.1% 90.1 34 29.9% 93.511 46 28.0% 95.911 66. 28.2% 96.111 93 22.6% 102.811 BORING H (CONTINUED) DESCRIPTION WITH SAND INTERBEDDED, SLI.CKENSIDES, AND VERTICAL SAND /SILT CONTACT IN SAMPLE GRAY SILT INTERBEDDED WITH SAND VERTICALLY GRAVEL OBSERVED BY DRILLER GRAY SILT INTERBEDDED WITH SAND LENSE.AT 70 DEGREE DIP ,GRAVEL.I.N BARREL ABOVE SAMPLE BORING COMPLETED AT 62'-z FEET ON 10/13/82 GROUND WATER OBSERVED AT 55 FEET DURING DRILLING -P1EZOMETER INSTALLED -AT 622 -FEET *SEE KEY FOR EXPLANATION OF SYMBOLS GeoEngineers Inc. LOG OF EXPLORATION FIGURE A -14 BORING J ELEVATION: 195.4 FEET *GRAPHIC *TEST DATA LOG DESCRIPTION 50 6' 23.5% 87.011 7 30.2% 90.4® 4.1 w 10-- 5 28.2% 95.811 15- 17 32.20 20 - 18 31.6% 91.011 25 - 18 31.8 %. 88 .,0 ■ 30 - 24 32.4% 90.011 3 5 - 22 32.3% 90.011 40 - SM BROWN GRAVELLY SILTY SAND WITH WOOD FRAGMENTS (MEDIUM DENSE, MOIST) ML GRAY SILT INTERBEDDED WITH SAND LENSES (SOFT, MOIST) GRADES TO STIFF WITH SLICKENSIDES AND FRACTURING FRACTURES SLICKENSIDES_ OCCASIONAL BROWN STAINS SLICKENSIDES *SEE KEY FOR EXPLANATION OF SYMBOLS GeoEngineers Inc. LOG OF EXPLORATION 40 *GRAPHIC *TEST DATA LOG BORING J (CONTINUED) DESCRIPTION 45- w 50 - Q 55- 60 - 65 - 70- 75 - 80 - 25 30.9% 92.6 23 32.0% 90.111 29 33.7% 89.011 23 28.7% 93.711 96 23.6% 100.9 47 25.9% 89.81 106 18.3% 106.111 59 6" 18.7% 110.211 ML ML GP WITH SLICKENSIDES AND BROWN STAINS LARGE SLICKENSIDE GRADES TO VERY STIFF FEW SLICKENSIDES WET SAND.LENSES AND RUST STAINS GRAY SILT WITH SOME GRAVEL, SLICKENSIDES, RUST STAINS, AND SAND LENSES (VERY STIFF, DAMP) HIT GRAVEL BETWEEN 77 TO 80 FEET *SEE KEY FOR EXPLANATION OF SYMBOLS GeoEngineers Inc. 1 LOG OF EXPLORATION FIGURE A -lb 80 *GRAPHIC *TEST DATA LOG BORING J (CONTINUED) DESCRIPTION 85— DEPTH IN FEET M LG 1 SP GRAY FINE TO MEDIUM SAND (MEDIUM DENSE, WET) HEAVE AT 82'11 FEET BORING COMPLETED A.T 84 FEET ON 10/15/83 GROUND WATER LEVEL ESTIMATED AT 491 DURING DRILLING .PIEZOMETER INSTALLED AT A DEPTH OF 822 FEET AND 20 FEET *SEE KEY FOR EXPLANATION OF SYMBOLS GeoEngineers Inc. LOG OF EXPLORATION DEPTH IN FEET BORING K ELEVATION: 175.0 FEET *GRAPHIC *TEST DATA LOG DESCRIPTION FIGURE A -17 10- 15- 20 - 25 - 30- 35- 40- 13 21.7% 99.611 9 26.3% 97.0 8 34.1% 87.711 10 8.3% 97.011 5 35.5% 87.311 20 29.8% 92.41 20 26.4% 93.511 36 26.1% 98.211 SM: BROWN GRAVELLY SILTY SAND WITH RED AND DARK BROWN STAINS (LOOSE TO MEDIUM DENSE, MOIST) ML GRAY SILT WITH SAND LENSES AND RUST STAINS (STIFF, MOIST) MOTTLED APPEARANCE GRADES TO SOFT AND WET SLICKENSIDES GRADES TO STIFF AND MOIST TO WET SLICKENSIDES AND BROWN STAINS SLICKENSIDES AND BLOCKY FRACTURES *SEE KEY FOR EXPLANATION OF SYMBOLS GeoEngineers Inc. 1 LOG OF EXPLORATION - FIGURE A -18 40 BORING K (CONTINUED) *GRAPHIC *TEST DATA LOG DESCRIPTION 45- H Gz; w 50- DEPTH IN 55- 60- 65- 70- 75- 80- 32 27•,7% 95.911 54 27.9% 96.711 31 27.1% 96.411 58 30.1 % 93.01 82 25.3% 98.411 76 27.0% 98.011 50 4" 24.5% 101.311 65 20.2% 110.01 ( ML MANY SLICKENSIDES. .VERTICAL COLOR CONTACT IN SILT SLICKENSIDES DISTORTIONS IN SAND LENSE SLICKENSIDES GRADES TO VERY STIFF MANY SLICKENSIDES SLICKENSIDE TRACE OF SOME VERY FINE SANDY WET VERY FINE SANDY SILT LENSES ML GRAY FINE SANDY SILT (STIFF, WET) UN /BROWN SILTY SANDY GRAVEL (DENSE, WET) *SEE KEY FOR EXPLANATION OF SYMBOLS GeoEngineers Inc. LOG OF EXPLORATION FIGURE A -19 80 BORING K (CONTINUED) *GRAPHIC *TEST DATA LOG DESCRIPTION 70 6" 23.0% 104.011 85- 50 4" 25.9% 98.8 w 90 -. DEPTH IN GP ML GRAY FINE SANDY SILT (STIFF, WET) BORING COMPLETED AT 88 FEET 9 INCHES ON 10/17/83 GROUND WATER LEVELS MEASURED AT 14 FEET AND 79.5 FEET DURING DRILLING PIEZOMETER INSTALLED IN GRAVEL LAYER AT 88 FEET -SEE KEY FOR EXPLANATION OF SYMBOLS GeoEngineers Inc. 1 LOG OF EXPLORATION APPENDIX B INSTRUMENTATION AND MONITORING PIEZOMETRIC LEVELS A series of water level measurements was made in the piezometers installed by GeoEngineers, Inc.; in Piezometers 1A, 1B, and 1 installed by Shannon & Wilson in 1966; and in the Group 1 vertical wells installed by the Washington State Department of Transportation (WSDOT) during construction of the I -5 /I -405 interchange in the mid- 1960s. The water levels measured in the piezometers and wells since November 1983 are presented in Tables B -1 through B -3. The elevation datum used is the Valvue Sewer District datum. INCLINOMETER DATA The inclinometer in Boring F was initialized on November 1, 1983. Subsequent sets of readings were taken on November 18, 1983 and March 12, 1985. The readings indicate no discernible movements at this time. The data are available for review or copying from our files. TABLE B -1 PIEZOMETRIC LEVELS — GEOENGINEERS, INC. BORINGS Ground Elevation of Water Table (Feet) Surface Elev. Boring (feet) 11/18/83 11/30/84 3/4/85 3/12/85 C 237.1 196.6 196 197 D 178.8 172.7(1) 172(1)(2) 123 123 G 179.2 163.3(1) 103 102 H 229.5 189.1 184.5 183.5 J(top) 195.4 184.1 184.5 185.5 185.5 J(bottom) 195.4 167.8(1) 114.5 166.5(1) 114.5 K 175.0 129.5 - (3) L 207.5 177.6 177.5 178 NOTES: (1) High water levels possibly due to surface water infiltration. (2) Reading obtained on 12/12/84. (3) Piezometer K plugged at 7 foot depth. TABLE B -2 PIEZOMETBIC LEVELS — SHANNON & WILSON PIEZOMETEBS Casing Elevation of Water Table Elev. (Feet) Piezometer (feet) 3/4/85 3/12/85 1A 148.5 93.5 93.5 1B 151.5 111.5 111.5 1(1) 165.0 146.5(1) 139 (1) NOTE: (1) Piezometer 1 consists of a slope indicator casing and is obstructed at Elevation 130. TABLE B -3 PIEZOMETRIC LEVELS - GROUP 1 WSDOT WELLS Casing Elevation of Water Table (feet) Elev. Well No. (feet) 11/30/84 3/4/85 3/12/85 1 161.4 143.5 144 144 2 162.6 148.5 147 147 3 162.8 152.0 152.5 152.5 4 166.2 - 101 101 5 166.5 103.5 104.5 104.5 6 166.4 - (1) - - 7 163.2 140 140 8 162.1 124 124 9 162.6 109.5 109.5 10 157.5 107.5 107.5 107.5 11 156.8 108 108 108 12 157.3 108.5 108.5 107.5 13 155.0 104 104 14 153.8 111 112 112 15 152.8 113 113 16 147.4 116.5 115.5 17 146.6 116.5 116.5 18 145.4 117.5 116.5 19 136.5 94.5 94.5 20 135.1 118 118 21a - (2) 21b 133.1 117 117 116 22 131.0 dry at 86' dry at 86' dry at 86' 23 131.3 96.5 97.5 24 130.3 97 96.5 NOTES: (1) Well No. 6 plugged at 9 foot depth. (2) Well No. 21a plugged at 10 foot depth. TABLE B -4 GROUP 1 WSDOT VERTICAL WELL /HORIZONTAL DRAIN SYSTEM Well Horizontal Drain Parameters Ground GEI WSDOT Surface Pump Elevation Outlet Well Well No. Elevation Elevation at Well Elevation Grade Length No. Series No. Feet Feet Feet Feet % Feet 1 I 1 159.6 60.1 80.9 80.5 2 213.0 2 2 160.1 61.0 82.6 80.5 1 222.6 3 3 160.5 56.0 81.6 80.5 2 223.1 4 II 1 164.6 54.5 82.1 81.7 2 233.6 5 2 164.3 51.8 82.8 82.8 2 223.4 6 3 164.1 51.6 86.9 82.6 2 223.6 7 III 1 162.3 53.4 83.4 83.3 2 223.7 8 2 161.5 51.3 88.0 83.9 2 212.8 9 3 161.0 52.7 86.5 84.4 1 213.7 10 IV 1 156.7 50.6 84.5 84.9 0 204.9 11 2 155.4 53.0 87.3 85.0 1 203.3 12 3 156.5 51.4 90.1 86.2 2 214.8 13 V 1 153.3 50.2 87.8 87.4 1 183.8 14 2 152.4 54.2 89.7 88.0 1 184.3 15 3 151.2 N/S 90.1 88.4 1 184.7 16 VI 1 145.7 42.5 90.6 89.8 2 17 152.8 2 144.7 N/S 92.0 90.6 1 153.2 18 3 143.8 62.8 92.4 91.0 1 152.9 19 VII 1 133.5 N/S 93.7 93.0 1 134.8 20 2 132.9 N/S 95.8 94.5 1 135.1 21 3 132.2 N/S 94.6 94.6 0 126.6 22 VIII 1 128.2 N/S 97.1 97.1 0 23 95.0 2 128.9 N/S 97.5 97.5 0 84.8 24 3 128.6 N/S 97.9 97.9 0 85.5 N /S. Not shown on WSDOT documents. B - 5 A P P E N D I E C SLOPE STABILITY ANALYSES INTRODUCTION A description of the slope stability analyses for the deep-seated sliding failure mode and the results are presented in this appendix. Methodology: Deep- seated block -type sliding was analyzed with the aid of the computer program STABL, which allows analyses of shear surfaces of general shapes, including sliding blocks. The program is based on Carter's Method. Critical failure surfaces are generated using pseudo random techni- ques. The input parameters include slope topography, piezometric levels in the lower sand aquifer, soil strengths, earthquake acceleration coefficients and building loads on the slope. The initial phase of our analyses included back - calculating soil strengths from conditions existing during sliding in 1961. The back - calculated soil strengths were obtained by changing the input values to achieve a computed factor of safety of about 1.0. These strengths, along with water level and topographic information were used to compute a new factor of safety for conditions existing in March 1985. The effects of water level rise, earthquake loading, and building loads on the factor of safety were then evaluated. Assumptions: Several assumptions were necessary in evaluating deep - seated block sliding stability. Topography representative of conditions existing in 1961 (soon after the major slide of 1960) and those existing at present (1985) were evaluated. Topographic conditions assumed in 1961 were based on Plate 3 of the Dames & Moore report dated June 27, 1961. Topographic conditions existing at present (1985) are based on topographic information provided by Stepan & Associates, Inc. for the section of the slope located between the uphill and downhill property lines. Topography below the downhill property line and above the uphill property line was estimated from Figure 1 in the Shannon & Wilson report dated June 21, 1968. The sections judged most critical of those used in our analyses are shown on Figures C -1 and C -2 for the 1961 and 1985 topographies, respectively. C - 1 The location of the section depicted on Figure C -1 and C -2 is shown on Figure 1. The location of the section used in the 1961 Dames & Moore report differs from that used in our analyses and is located to the southeast of the section we have used. The section shown on Figure C -2 is drawn through the center of a large swale, while the borings drilled both for our studies and by Dames & Moore are located on the flanks of this swale. The differences in topographic conditions shown in 1961 and 1985 indicates that a significant amount of material is absent from the lower portion of the slide area, particularly below the downhill property line. The difference could be attributable to material removal as well as to the different sections used by Dames & Moore and GeoEngineers. Soil conditions depicted in all of the borings used to develop our cross sections vary significantly. This is especially true of Borings DM -1 and D, DM -3 and G, and DM -4 and C. Variations across the swale are also apparent when comparing the logs for Borings DM -1 and DM -3 with D and G, respectively. The presence and variable elevations of sand lenses throughout the thick fine - grained layer (Unit B) probably account for the major part of this variability. They also have a significant influence on the location of the failure surface. The location of failure zones identified from slope indicator measurements in the Dames & Moore borings and zones of slickensided material encountered in Borings C, D, G, L and F were used to estimate the probable location of the slide plane in our analyses. See Figure 1. For both topographic conditions (1961 and 1985), the soil conditions were simplified to a three -layer system. The uppermost layer includes the surficial silty sand and thick fine - grained soil units (Units A and B shown in Figure 1). The second layer (underlying the thick fine - grained soil unit) was assumed as a thin (5- foot - thick) zone of weak material through which the slide plane passes. Material underlying this weak layer was assigned a higher strength and represents dense glacially compacted soils through which the slide plane probably does not pass. The extent of the weak zone was estimated from our borings and the Dames & Moore borings. C - 2 Water levels for the 1961 analysis had to be estimated as artesian conditions existed at the time the borings were drilled by Dames & Moore in 1961. Based on the observations by Dames & Moore personnel of the rate of flow from the borings, the piezometric surface was assumed at 5 feet above the existing ground surface. Water level information from our borings and Shannon & Wilson Piezometers 1, 1A and 1B were used to establish the piezometric surface existing in 1985. The sliding block failure surface was modeled using five constraint areas positioned along the lower boundary of the assumed weak zone. The downhill exit point for the slide was based on the exit point indicated in the 1961 Dames & Moore report. This exit point may have been observed at that time because this portion of the site was cleared as a result of borrow operations. The failure surfaces are shown in Figures C -1 and C -2 for 1961 and 1985, respectively. Selection of Parameters: The analyses using 1961 conditions were performed by varying soil strengths of the upper two soil layers until a factor of safety of approximately 1.0 was obtained. The friction angles for this condition were computed at 25 degrees for the upper material and 15 degrees for the weak zone material. These friction angles are considered to be residual values and the cohesion intercepts were accordingly assumed to be zero. The analyses indicate a zone of critical failure surfaces having nearly equal factors of safety near the uphill property line. See Figure C -1. Results: The failure surface and piezometric conditions evaluated for existing conditions are shown in Figure C -2. The analyses indicate a factor of safety of 1.5 to 1.6 for the section assumed in the analysis. Our analyses of the stability of sections located outside of the swale yield factors of safety approximately the same for existing piezometric conditions. Additional Analyses: We then evaluated the effects of an increase in the water level. Factors of safety of 1.3 and 1.0 were obtained when the piezometric levels were raised 10- and 20 -feet, respectively, above existing levels. C - 3 We also evaluated the effect of the building loads on deep- seated stability by assuming an average areal building load of 200 pounds per square foot extending over the building footprints at two locations on the slope. The factor of safety obtained for this loading condition was nearly identical with that obtained without building loads. Dynamic Analysis: Dynamic stability was evaluated by subjecting the slope to a horizontal acceleration coefficient of 0.15 with the piezometric surface at current levels. We assigned a cohesion value of 500 psf and a friction angle of 15 degrees to the weak zone to represent undrained soil strength. This is considered to be conservative and to be more appropriate for earthquake loading. A factor of safety of 1.13 was obtained for these conditions. While the factor of safety indicated for dynamic loading conditions is relatively low, this value is considered, in general practice, to provide a level of risk comparable to a factor of safety of 1.5 for static conditions. Strains and, therefore, slope movement developed during earthquake loading will probably be limited. This is normally observed in cohesive soils during earthquake loading and is indicated by the reported localized zones of cracking in the uphill portion of the slide area during the 1965 Seattle earthquake. C - 4 FIGURE C -1 360 320 280 240 1— w w 200 z ELEVAT ION 160 120 80 40 (0, 100) (96,116) (0,64) (120,88) (243,162) PROPERTY LINE 1961 Topography ESTIMATED PIEZOMETRIC LEVEL (364,173) ' (332,164) (364,138) (364,133) SLIDING BLOCK FAILURE SURFACE (526,190) (526,171) (526,166) ZONE OF GENERATED CRITICAL FAILURE SURFACES PROPERTY LINE Cs 90 SLADE WAY. (728, 252). (786,253) SOIL ff' 0 (880,275) = 125 PCF = 0 2880,228) (880,209) (880,204) SOIL 0 - it = 120 PCF C = 0' = 15° SOIL 0 a = 130 PCF C = 0 0 = 35° — 360 — 320 — 280 — 240 f— w w -200 w z 160 120 —80 :40 0 40 80 120 160 200 240 NOTES: 1) SECTION LINE IS SECTION A —A' SHOWN IN FIGURE 1. 2) TOPOGRAPHY BASED ON PLATE 3 IN DAMES & MOORE REPORT DATED 6/27/61 AND CORRESPONDS TO CONDITIONS EXIST- ING AFTER SLIDE OF 1960 -61. 3) WATER LEVELS ESTIMATED FROM BORINGS DRILLED BY DAMES & MOORE IN 1961. 280 320 360 400 440 I 1 I 480 520 560 DISTANCE IN FEET 600 640 680 720 760 800 840 880 0 ELEVATION GeoEngineers Inc. CROSS SECTION FOR STABILITY ANALYSIS FIGURE C -2 ELEVATION IN FEET 360 - 320- 280 - 240 - 200 - 160 - 120 - 80 1985 Topography, PROPERTY LINE ESTIMATED PIEZOMETRIC SURFACE 1457,171) (542,200) PROPERTY LINE SLADE WAY ZONE OF GENERATE) CRITICAL FAILURE SURFACES (72:,252) (786,253) (880,275) - 360. - 320 - 280 - 21+0 (880,204) (526,177) (302,141) (526,166) 64,1.3.11 (526, 171) (364,133) 0,100) 6 = 130 PCF C = 0 0 = 35° (120,93) (242,115) (0,69) 0,76) (120, 88) SLIDING BLOCK FAILURE SURFACE 40 - 0 (880,228) (880,204) 200 t- w W A, LL z_• - 160 z. 0 1- w -120 -J - 80 - 40 0 40 80 120 160 200 240 NOTES: 1) SECTION LINE IS SECTION A -A' SHOWN IN FIGURE 1. 2) TOPOGRAPHY BELOW DOWNHILL PROPERTY LINE AND ABOVE UPHILL PROPERTY LINE BASED ON FIGURE 1 IN SHANNON & WILSON REPORT DATED 6/21/68. 3) TOPOGRAPHY BETWEEN PROPERTY LINES BASED ON PRE- LIMINARY TOPOGRAPHIC MAP PROVIDED BY STEPAN & ASSOCIATES, INC., DATED MARCH, 1985. 4) WATER LEVELS BASED ON MEASUREMENTS MADE IN PIEZOMETERS INSTALLED BY GEOENGINEERS AND SHANNON & WILSON, AND IN GROUP 1 VERTICAL DRAINAGE WELLS INSTALLED BY WSDOT. 280 320 360 1 f I 400 440 480 DISTANCE IN FEET 520 560 600 GeoEngineers Inc. 1 640 680 720 760 800 840 880 0 ;',CROSS SECTION FOR STABILITY ANALYSIS