Loading...
HomeMy WebLinkAboutPermit L94-0102 - CITY OF TUKWILA - 51ST AVENUE SOUTH BRIDGE REPLACEMENTL94 -0102 51STAVE. S. BRIDGE REPLACEMENT: CITY OF TUKWILA MITIGATED. :ETERMINATION OF NONSIGNIF( INCE (MDNS) DESCRIPTION OF PROPOSAL: 51 AVE. S.(spaning 5.154) BRIDGE REPLACEMENT PROPONENT: PUBLIC WORKS DEPT. LOCATION OF PROPOSAL, INCLUDING STREET ADDRESS, IF ANY: ADDRESS: 51st Ave. S. and S. 154th St. PARCEL NO: SEC /TWN /RNG: Section 22 & 23,Township 23N, Range 4E, WM., City of Tukwila LEAD AGENCY:. CITY OF TUKWILA FILE NO L94 -0102 The City has determined that the proposal does not have a.probable significant adverse impact on the environment. An environmental impact statement (EIS) is not required under RCW 43.21c.030(2)(c). This decision was made after review of a completed environmental checklist and other information on file with the lead agency. This information is available to the public on request. The conditions to this SEPA Determination are attached. This. DNS is ss ed under 197. -11- ;340(2).5 Comments must be submitted by _ The lead agency will not act on this for. 15 days from the date below. ': 2.Y- S sr Steve Lancaster, Responsible Official Date City of 'Tukwila, ". (206) 431 -3680 6300 Southcenter Boulevard Tukwila, WA 98188 You may appeal this determination to the City Clerk at City Hall, 6200 Southcenter Boulevard, Tukwila, ` WA 98188' no later; than 10 days from the above signature date by written appeal stating the basis of the appeal for specific factual objections. You may be required 'to bear some of the expenses for an appeal. Copies of the procedures for. SEPA appeals are avalIable with the City Clerk and Department of Community Development. . A F F I D A V I T r, Kble`1v,2oloblV1S O Notice of Public Hearing O Notice of Public Meeting O Board of Adjustment Agenda Packet LI Board of Appeals Agenda Packet fl Planning Commission Agenda Packet O Short Subdivision Agenda Packet O F D I S T R I B U T I O N hereby declare that: LI Notice of Application for Shoreline Management Permit LIShoreline Management Permit LI Determination of Non - significance LI Mitigated Determination of Nonsignificance LI Determinatio_n of Significance and Scoping Notice fl Notice of Action LI Official Notice 0 Other 0 Other was mailed to each of the following addresses on Name of ProjectVf L ' Britutoit, t% n Jn n n hV�L�/�+ File Number in - bl o w CHECKLIST: ENVY 'NMENTAL REVIEW /SHORELINE 13-79RMIT MAILINGS FEDERAL AGENCIES Gam 1U.S. ARMY CORPS OF ENGINEERS /( )FEDERAL HIGHWAY ADMINISTRATION .DEPT. OF INTERIOR -FISH & WILDLIFE SERVICE OFFICE OF ARCHAEOLOGY TRANSPORTATION DEPARTMENT DEPT. OF NATURAL RESOURCES )OFFICE OF THE GOVERNOR )DEPT. OF COMMUNITY DEVELOPMENT EPT. OF FISHERIES WASHINGTON ( )U.S. ENVIRONMENTAL PROTECTION AGENCY ( )U.S. DEPARTMENT OF H.U.D. (REGION X) STATE AGENCIES V(()K.C. PLANNING & COMMUNITY DEV. ( )BOUNDARY REVIEW BOARD ( )FIRE DISTRICT #11 ( )FIRE DISTRICT #2 ( )SOUTH CENTRAL SCHOOL DISTRICT ( )TUKWILA LIBRARIES ( ) RENTON LIBRARY. ( )KENT LIBRARY ( )CITY OF SEATTLE LIBRARY ( )US WEST ( )SEATTLE CITY LIGHT ( )WASHINGTON NATURAL GAS ( )WATER DISTRICT #75 ( )SEATTLE WATER DEPARTMENT ( )GROUP W CABLE ( )OLYMPIA PIPELINE ( )KENT PLANNING DEPARTMENT ( ) UKWILA CITY DEPARTMENTS: vflt>dPUBLIC WORKS ( ) FIRE (- )POLICE ( )FINANCE )PLANNING ( )BUILDING ( )PARKS AND ORECREATION / TUKWILA MAYOR ( )DEPARTMENT OF SOCIAL &HEALTH SERVICES DEPT. OF ECOLOGY, SHORELANDS DIVISION DEPT. OF ECOLOGY, SEPA DIVISION* EPARTMENT OF WILDLIFE )OFFICE OF ATTORNEY GENERAL *SEND CHECKLIST WITH DETERMINATIONS AND *SEND SITE MAPS WITH DECISION KING COUNTY' AGENCIES ( )KING COUNTY '•DEPT. OF PARKS ( )HEALTH DEPARTMENT ( )PORT OF SEATTLE ( )BUILDING & LAND DEV. DIV.- ' SEPA INFORMATION CENTER SCHOOLS /LIBRARIES ( )HIGHLINE SCHOOL DISTRICT ( )KING COUNTY PUBLIC LIBRARY ( )SEATTLE MUNICIPAL REFERENCE. LIBRARY ( )SEATTLE SCHOOL DISTRICTS ( ) RENTON SCHOOL-DISTRICT UTILITIES ( )PUGET SOUND POWER & LIGHT ( )VAL -VUE SEWER DISTRICT ( )WATER DISTRICT #20 ( )WATER DISTRICT #125 ( )CITY OF RENTON PUBLIC WORKS. ( )RAINIER VISTA ( )SKYWAY CITY AGENCIES V),RENTON PLANNING DEPARTMENT ( )CITY OF SEA -TAC ( )CITY OF SEATTLE ( )CITY OF BURIEN ( )TUKWILA PLANNING COMMISSION MEMBERS ( )TUKWILA CITY COUNCIL MEMBERS OTHER LOCAL AGENCIES ( )PUGET SOUND REGIONAL COUNCIL ( )P.S. AIR POLLUTION CONTROL AGENCY ( )SW K.COUNTY CHAMBER OF COMMERCE )MUCKLESHOOT INDIAN TRIBE - ( DUWAMISH INDIAN TRIBE MEDIA ( )DAILY JOURNAL OF COMMERCE ( )VALLEY DAILY NEWS ( )METRO ENVIRONMENTAL PLANNING DIV. OFFICE /INDUSTRIAL 5,000 GSF OR MORE RESIDENTIAL 50 UNITS OR MORE RETAIL 30,000 GSF bR MORE ( ) HIGHLINE TIMES ( )SEATTLE TIMES PUBLIC NOTICE MAILINGS FOR PERMITS SEPA MAILINGS Mail to: (comment period starts on date of mailing) Dept. of Ecology Environmental Review Section Applicant Other agencies as necessary (checked off on attached list) Include these documents: SEPA Determination (3 -part form from Sierra) Findings (staff report, usu. with MDNS) - SEPA Checklist (filled out by applicant) Drawings /Plans of project (site plan, elevations, etc. from PMT's) Affidavit of Distribution (notice was mailed & sent to newspaper). SHORELINE MAILINGS Notice of Application: Notice of application for a substantial development Permit must be mailed to owners and to property owners within 300 feet of subject property, prepare an affidavit of publication, and publish two consecutive weeks with deadline for comments due 30 days after last newspaper publication date. Shoreline Permit: Mail to: ('within 8 days of decision; 30 -day appeal period begins date received by DOE) Department of.Ecology Shorelands Section State' Attorney General - --- Applicant Indian Tribes Other agencies as necessary (checked off on attached list). Include these documents: Shoreline Substantial Development Permit (3 -part form from Sierra) Findings (staff report, if applicable) Shoreline Application Form (filled out by applicant) Drawings /Plans of project (site plan, elevations, etc. from PMT's) Site plan', with mean high water mark & improvements _ Cross - sections of site w /structures & shoreline Grading plan _ Vicinity map SEPA Determination (3 -part form from Sierra) Findings (staff report, usu. with MDNS) SEPA Checklist (filled out by applicant) Any background studies related to impacts on shoreline Notice of Application Affidavit of Distribution (notice was mailed & sent to newspaper) Affidavit of Publication (notice was published in newspaper). MEMORANDUM DATE: March 8, 1995 TO: Libby Hudson FROM: Ross Heller/Leslie Tauzer RE: L94 -0102, 51st Ave. Bridge SEPA Public Works # 92 -RW12 Enclosed, please find a response to your memorandum dated December 15, 1994 requesting additional information to complete the review of the SEPA Checklist. 1. Sensitive Areas The soils reports that you requested are attached. Please note there are two separate reports, one for the bridge construction and one for the roadway improvement along 51 Avenue South. Gilliam Creek is being temporarily piped through the R/W to allow for construction. At the completion of the project, the creek will be restored to it's present condition and location. Gary Schulz is working with Public Works on the creek restoration plan. 2. Existing Bridge The existing bridge is being replaced for the following reasons: The existing bridge is in poor structural condition. The roadway deck is heavily cracked, the girders and beams are corroded, and concrete spalling has occurred on some anchorages and columns. The bridge structure is not sufficient to carry a legal load and is posted. The bridge is too narrow and does not provide the required safety for pedestrians. The site distance along 51 Ave S is very poor and poses a safety concern. The existing bridge demolition is proposed to occur as follows: The concrete deck will be sawcut and removed in pieces. The bridge girders and beams will be removed with a crane after detaching connections using torches or sawcutting methods. The existing piers will be removed to just below grade, where possible. If the existing pier or its foundation interferes with the new bridge construction, the surrounding area will be excavated and the existing foundation removed as well. Existing piles will be left in place. • 2. Existing_Bridge (con't) The existing abutments will be removed. During the periods of demolition and construction, protection will be provided for the creek and surrounding areas. 3. Detour The draft detour plan for vehicles is attached. Pedestrian traffic is "non- existent" across the 51 Ave S Bridge; pedestrians have not been observed in studies or during numerous visits to the bridge. The existing bridge has (2) 10 foot +1- lanes and no provision for. pedestrians. No economically feasible pedestrian detour between Klickitat and 51 Ave S is planned. 51 Ave S pedestrian traffic will continue to use 51Ave S, S 150 or S 144. Stranded SR518 motorists can continue to use Klickitat to Southcenter Parkway. MEMORANDUM DATE: DECEMBER 15, 1994 TO: -ROSS - HELLER (.1l` Cam` FROM: LIBBY HUDSON 4 -0 BRIDGE RE: L9 02 1 51ST AV. R IDGE EPA A preliminary review of the Environmental Checklist indicates that more information is needed in order to process the SEPA Checklist and make a determination. 1. Sensitive Areas Because this project involves both sensitive slopes and a watercourse, TMC 18.45, Sensitive Areas Overlay Zone, is triggered. I've attached a copy of the sections that apply to this project. Construction and development within Class 4 slopes require that a geotechnical report be submitted [TMC 18.45.040 (d) (1)j. Please submit a geotechnical report which meets all the requirements of section TMC 18.45.080 (e)(4). This needs to be reviewed prior to making the SEPA determination. Diverting Gilliam Creek requires approval from the DCD Director and a mitigation plan [TMC 18.45.080 (d) (1)(B), (2). I will check with Gary Schulz regarding re- vegetation plan he may be working on. sct■cl .—` Op' C2 ( •I,, ctt�oAL LL -Ir �I"�a, 2. Existing Bridge , _( n ■ Please state why the existing bridge is being replaced. Please explain how the bridge ad V t e demolition will be conducted so that assessment of potential impacts can be addressed in this 1 I SEPA. Otherwise another environmental review process will be required for the bridge f 1 demolition. 3. . Detour Please provide a detour plan for vehicular traffic and pedestrian movement. I have requested comments from the Washington State Department of Fish and Wildlife and the Department of Transportation. These should be back by December 30, 1994. If you could get the geotechnical report and Gilliam Creek information to me by then or by the first of the year, we should hopefully be able to finish the review by mid- January C: Gary Schulz `. City of Tukwila Department of Community Development December 14, 1994 Washington State Department of Fish and Wildlife 16018 Mill Creek Blvd. Mill Creek, WA 98012 Washington State Department of Transportation TSM &P/ Environmental Review 6431 Corson Ave. s. Seattle, WA 98108 RE: 51st Avenue Bridge Replacement SEPA, #L94 -0102 John W. Rants, Mayor Rick Beeler, Director Dear SEPA Reviewer: Prior to making a SEPA determination on the above mentioned Environmental Checklist, the City of Tukwila would like your departments comments. Please review the attached environmental checklist and comment by December 30, 1994. Sincerely, Libby Hudson Associate Planner enclosure 6300 Southcenter Boulevard, Suite #100 • Tukwila, Washington 98188 • (206) 431-3670 • Fax. (206) 431-3665 CITY TUKWILA CONDITIONS Address: Applicant: Status: PENDING Permit No: L94 -0102 Applied: 11/17/1994 Type: P -SEPA DNSC Approved: Location: Section 22 & 23,Township 23N, Range 4E, WM., City of Tukwila Parcel #: Zoning: ******************************************** * * * * * * * * * * * * * * * * * * * * * * * * * * * * * ** 1. Slope stability and erosion control measures shall be implemented during construction, as recommended by the geotechnical report, (GeoEngineers, February 8, 1995). 2. A geotechnical engineer shall be on -site during fill placement as recommended by the geotechnical report. 3. The majority of the construction should take place during the dry season to reduce impacts to the diverted stream and to increase slope stability. 4. A final enhancement plan which conforms with the Sensitive Areas Overlay Zone shall be submitted for review and approval to the Department of Community Development prior to issuance of a land altering permit. ENVIRONMENTAL CHECKLIST REVIEW FILE: #L94 -0102 DATE: May 17, 1995 PROPOSAL: 51st Avenue S. (S 154th) Bridge Replacement APPUCANT: City of Tukwila, Public Works Department GENERAL PROJECT DESCRIPTION The project includes the construction of a replacement bridge spanning S. 154th Street and Gilliam Creek. The existing two -lane bridge is in poor structural condition. The proposed bridge will span approximately 200 feet, at a height of approximately 38 feet. It will serve two lanes of traffic and pedestrians at a slightly wider dimension than the existing bridge provides. Gilliam Creek will be temporarily diverted during the construction of the bridge foundation. The crossing will be closed to traffic for one year. Detour routes will be established to accommodate the approximate 4,000 average daily trips (ADT) which use the crossing. The creek habitat will be restored following the completion of the bridge construction. The following is an environmental analysis based on the environmental checklist and additional information provided. Earth The existing slope of the ravine in which the bridge spans is steep with an approximate 70% slopes. The slopes are identified as 'Class 4 Areas' in the City's Sensitive Areas Overlay Zone [TMC 18.45.020 (e)] A geotechnical report (GeoEngineers, February 8, 1995), as required under TMC 18.45.040 (d)(1), was completed for this project. According to the geotechnical report the existing soils consist of approximately 6 feet of fill and loose to medium dense sand underlain by silt and hard sift and very dense glacial till. The report recommends that the very dense glacial till can support the proposed bridge with conventional spread foundation footings. The underlining silt tends to prevent infiltration of precipitation and creates 'perched' groundwater conditions . To accommodate the existing and future expansion of S. 154th Street, located under the bridge span, the east bank will be excavated. Little disruption to the west bank will occur as a result of the bridge construction. Unsupported cut slopes will be limited to 1.5H:1V maximum, with greater cuts being retained with walls. To construct the bridge and approach, the existing organic layer will be removed and suitable fill material will be placed along the alignment. Approximately 3,000 cubic yards of fill will be imported to the site for the bridge construction. Slope Stability The geotechnical report evaluated several slope support alternatives for the fill. According to the report the most suitable alternative is a MSE Geogrid system with interceptor drains, removal of existing roadway fill and lengthening the geogrids to improve global stability. The MSE Geogrid system can support fill up to 20 feet. The geogrids are embedded in the compacted fill as the level of fill is raised. The geotechnical report recommended that a geotechnical engineer be on site to observe the placement and compaction of the roadway fill to insure that filling is completed as recommended in the report. Slope cuts, according to the report, should not exceed 2H:1V, which is greater than proposed for the project. The report states that gravity block walls are sufficient to maintain cut slopes that do not exceed 5 feet in height. The geotechnical report strongly recommend that the work be accomplished during the late summer /early fall due to moisture - sensitive soils. To reduce potential adverse impact to the existing slopes, the recommendations of the geotechnical report should be followed. Erosion There is potential for erosion to occur as a result of construction of the project. Temporary erosion control measures will be employed during the site work. Both temporary and permanent erosion control measures are outlined in the geotechnical report. These measure should be followed to reduce the adverse impact erosion could cause to the creek and the slopes. WATER The bridge will cross Gilliam Creek which is designated Type 2 watercourse, sensitive area.. This creek is proposed to be temporarily piped during construction of the bridge. The work is to take place during the dry season, at low flow of the creek. Water runoff and Stormwater All roadway surface water runoff will be collected and directed to the public stormwater system. In addition, surface water and groundwater collected by interceptor drains, as recommended in the geotechnical report, should also be directed to the public stormwater system. PLANTS The project includes removal of trees, shrubs, and ground cover to construct the new bridge and widen the approach. Disturbed areas will be re- vegetated. Re- vegetation is planned for the new slopes. LAND AND SHORELINE USE The proposal bridges Gilliam Creek, a Type 2 Watercourse, which will temporarily diverted during construction. After completion of the bridge, the creek is to be restored and enhanced with riparian plantings. A conceptional enhancement plan has been provided. The final enhancement plan will be designed and reviewed during the permitting stage of the project. The final enhancement plan will be reviewed by the Department of Community Development and must be in compliance with the Sensitive Areas Overlay Zone before a land altering permit can be issued. TRANSPORTATION The project replaces the existing bridge, causing no expected increase in traffic volumes. A detour route will be in effect for one year during the construction. This will temporarily limit traffic crossing, and detour traffic north of the crossing along Macadam Avenue to Southcenter Boulevard. Traffic to the south of the crossing will be detoured along 51st Avenue S. to Southcenter Boulevard. The existing bridge has no accommodation for pedestrians, there is virtually no pedestrian circulation to disrupt. RECOMMENDATION Based on the analysis in this report, it is recommended that this project be issued a Mitigated Determination of Nonsignificance (MDNS) with the following conditions: 1: Slope stability and erosion control measures shall be implemented during construction, as recommended by the geotechnical report,(GeoEngineers, February 8, 1995). 2. A geotechnical engineer shall be on -site during fill placement as recommended by the ' geotechnical report. 3. The majority of the construction should take place during the dry season to reduce impacts to the diverted stream and to increase slope stability. 4. A final enhancement plan which conforms with the Sensitive Areas Overlay Zone shall be submitted for review and approval to the Department of Community Development prior to issuance of a land altering permit. : Report. Geotechnical Engineering Services 51st Avenue South Roadway improvement* - Tukwila., Washington • • February 8.1995 For J City: of Tukwila e o E n g i n c c r s GeoN0 Engineers City of Tukwila c/o Sargent Engineers, Inc. 320 West Bay Drive, Suite 101 Olympia, Washington 98502 Attention: Mr. Steve Roberts. P.E. February 8, 1995 Geotechnical, Gcocnvironmental and Geologic Services Report Geotechnical Engineering Services 51st Avenue South Roadway Improvement Tukwila, Washington File No. 0259- 029 -R06 INTRODUCTION This report presents the results of our geotechnical engineering services for roadway improvements to 51st Avenue South near the bridge crossing of South 154th Street in Tukwila, Washington. The proposed roadway widening project site is shown on the Vicinity Map and Site Plan, Figures 1 and 2, respectively. Our work on this project has been done in general accordance with our proposal to you dated July 5, 1995. You have provided us with a topographic survey and roadway profiles for the project which include the proposed location of the improvements and grading geometry. We have discussed project details with Messrs. Steve Roberts, Nicholas Afeiche and Michael Pillion of Sargent Engineers. PROJECT DESCRIPTION The project site extends along 51st Avenue South from the South 154th Street bridge overcrossing northward for about 900 feet to near the intersection with South 151st Street. Currently, 51st Avenue South at the project site climbs a steep grade northward from the bridge and then abruptly flattens causing reduced sight distance for traffic. The project plans include widening and grading the roadway alignment to improve the sight distance. The plan and profile sheets which you provided indicate cuts up to 3 feet between Stations 6 +50 and 8 +20 and fill up to 4 feet between Stations 9 +00 and 10 +80 along the centerline. Widening the roadway will GeoEngineers, Inc. 8410 154th Avenue N.E. Redmond, WA 98052 Telephone (206) 861 -6000 Fax (206) 861-6050 City of Tukwila February 8, 1995 Page 2 require up to 9 feet of fill near Station 10 +00. The preliminary design of the roadway widening utilizes stone block walls and /or MSE (mechanically stabilized earth) geogrid systems. Rockeries are not being considered for cut slope protection as requested by the City of Tukwila. SCOPE The purpose of our work is to explore and evaluate subsurface conditions as a basis for providing recommendations for the roadway improvement. More specifically, our work consists of: 1. Performing a field reconnaissance of the project site to identify existing and potential seepage zones and other pertinent features. 2. Excavating five test pits at selected locations along the shoulder of the road at the project site. 3. Developing recommendations for cut and fill slopes, including consideration of flatter slopes or use of retaining structures. 4. Discussion of retaining structures. 5. Recommendations for temporary and permanent drainage measures, including erosion and sedimentation control measures. SITE CONDITIONS SURFACE CONDITIONS The roadway within the Limits of the project site currently traverses an east - facing hillside with cuts ranging up to 5 feet on the west shoulder and fills ranging up to 8 feet on the east shoulder. The existing cut slope along the uphill shoulder is inclined at about 1H:1V (horizontal to vertical) and is vegetated with grass. The fill along the downhill shoulder is inclined at about 1.5H:1V and is generally vegetated with grass and blackberry vines. A shallow ditch occurs along the uphill shoulder of the road from the bridge to about Station 8 +00. Seepage is emanating from the cut slope into the ditch at Station 5 +90 (a tile yard drain), at Station 6 +45 (another tile yard drain) and at Station 7 +00 (shallow ground water seepage). Ground water seepage also occurs between Stations 10 +20 and 11 +20 and is emanating from the cut slope face. There is no ditch in this area so water is ponding along the shoulder and is infiltrating into the roadway subgrade soils. We did not observe seepage along the downhill shoulder of the road. Longitudinal cracks in the asphalt pavement were observed in the northbound traffic lane between Stations 9 +75 and 10 +05, and Stations 10 +80 and 11 +25. The adjacent properties uphill are occupied by single- family residential structures probably built sometime in the 1950s; the adjacent properties downhill of 51st Avenue South are undeveloped. We observed a 12- to 15- foot -high rockery that borders a parking lot between Stations 7 +00 and 9 +00 and about 40 feet east of the edge of the road. We observed a second G c o E n g i n e c r s Fite No. 0259- 029 -R06 City of Tukwila February 8, 1995 Page 3 rockery about 4 feet high and about 10 feet east from the edge of the road between Stations 9 +70 and 10 +00. We also observed a 6- to 7- foot -high, outward leaning concrete block wall about 25 feet east of the roadway shoulder between Stations 6 +50 and 7 +00. SUBSURFACE EXPLORATIONS Subsurface conditions were evaluated by excavating 5 test pits with a backhoe and operator provided by th3 City of Tukwila on January 12, 1995. The test pits were generally excavated into the existing cut slope along the uphill shoulder and into the fill slope along the downhill shoulder. The approximate locations of the explorations are shown on the Site Plan, Figure 2. The locations were determined by pacing or tape- measurement from existing site features as shown on the project topographic drawing. The explorations were continuously monitored by an engineering geologist from our firm who observed and classified the soils encountered, maintained a log of the subsurface conditions, and obtained representative soil samples. The test pits were backfilled with material derived from the excavations. The backfill was tamped in place and smoothed. We recommend that prior to construction in the areas of the test pits, the backfill should be removed and replaced as structural fill. SUBSURFACE CONDITIONS The soils encountered in Test Pit Nos. 1, 2 and 5, excavated along the uphill shoulder of 51st Avenue South, are comprised of about 2 feet of medium dense silty sand and soft to medium stiff sandy silt underlain by very stiff to hard silt. Test Pit No. 3 was excavated along the east shoulder near Station 7 +50 in an area where about 3 feet of cut is planned. This test pit encountered 2 to 3 feet of medium stiff silt with occasional roots underlain by very stiff to hard silt. Test Pit No. 4, excavated along the downhill shoulder area opposite South 152nd Street where about 9 feet of fill is planned, is comprised of 8 feet of medium dense silty sand and fine to medium sand, and medium stiff silt with a trace of gravel. This 8 -foot layer of soil appears to be fill placed for the original street construction. Underlying the fill is very stiff to hard silt. The very stiff to hard silt encountered in the lower part of the test pits is a native soil which has been glacially overridden. Ground water seepage was encountered in Test Pit No. 1, 2 and 5 at the interface between the surficial weathered soils and the native very stiff to hard silt. No ground water was observed in Test Pit Nos. 3 and 4. G c o E n g i n c c r s Filc No. 0259- 029 -R06 " G e o En g i nee r s File No. 0259- 029 -P.06 City of Tukwila February 8, 1995 Page 5 Roadway Fill Material Roadway fill material should be free from debris, organic contaminants and rock fragments larger than 6 inches. Particles larger than 6 inches should be excluded from the top 1 foot of fill. We recommend that fill material placed in the upper •1 foot of the roadway subgrade contain no more than 5 percent fines to help improve pavement drainage. Compaction Requirements We recommend that the upper 2 feet of roadway fill and all fill placed on the slopes be compacted to at least 95 percent of the MDD (maximum dry density) determined in accordance with ASTM D -1557. The remainder of the fill should be compacted to at least 90 percent unless otherwise specified by the manufacturer of the geogrid system, as appropriate. Use of On -site Soils for Structural Fill The suitability of soil for use as structural fill will depend on its gradation and moisture content at the time of placement. As the amount of fines increases, soil becomes more sensitive to excess moisture. Adequate compaction of soil with a high fines content and excess moisture may be impossible to achieve. Based on our observations, the on -site nonorganic soils will only be suitable for roadway fill during extended periods of dry weather when the moisture content can be controlled. The on -site soil will not be suitable for use as roadway fill during wet weather or for use in the construction of MSE geogrid systems as described later in this report. FILL PLACEMENT ON SLOPES No fill or retaining structures should be placed on the fill which currently exists on the slope. No unreinforced or unretained fill should be placed on slopes steeper than 211:IV. If any fill is placed on slopes steeper than 5H:1V, it should be benched into the slope face. Bench excavations should be level and should extend into the slope face until a vertical step of about 3 feet is constructed. The benches effectively "key" the fill into the existing slope. The excavated materials, if suitable, may be used as structural fill. CUT AND FILL SLOPES Temporary slopes may be necessary during site grading and construction. Where weathered or medium dense soils are encountered, temporary cut slopes of 1.5H:1V or flatter may be used provided that no significant ground water seepage is encountered. Flatter cut slopes are recommended when significant seepage is encountered. In any case, it is the sole responsibility of the contractor to follow WISHA (Washington State Industrial Safety and Health Act) regulations for excavations and shoring. G c o E n g i n e c r s File No. 0259- 029 -R06 City of Tukwila February 8, 1995 Page 6 We recommend permanent cut and fill slopes be constructed at a maximum inclination of 2H:1V. Where 2H:1V permanent slopes are not feasible, slope support structures or MSE geogrid systems should be used. FILL RETAINING STRUCTURES General Because of grade separation and right -of -way constraints along the downhill shoulder of the roadway, it is likely that permanent structural retaining structures will be needed. Based on the preliminary design drawings, the proposed wall height will be about 9 feet with an approximately 9- foot -high 1.5H:1V fill slope extending from the top of the wall to the new roadway shoulder. As discussed above, we recommend that any new retaining structure not be founded on the existing fill on this area. We also recommend 2H:1V permanent slopes, unless the slope is reinforced. Alternative retaining structures include reinforced concrete walls, soldier pile walls and MSE geogrid systems. We understand that a MSE geogrid system is the preferred method of slope support. The following is a summary of our evaluation of the retaining structure alternatives: Concrete Walls Conventional concrete retaining walls are generally cost - effective up to a height of around 8 to 10 feet if cantilevered. A conventional reinforced concrete wall may provide a more attractive finished face and be less expensive than a soldier pile wall, but will require additional excavation into the slope, and may require shoring of the slope during construction in steeper areas. Soldier Pile Walls Cantilever soldier pile walls are generally cost - effective up to 12 to 14 feet in height. Depending on the need for temporary shoring and limited accessibility, a soldier pile wall may be a cost - effective option for the project. MSE Geogrid Systems MSE geogrid systems are an economical means of retaining fills up to 20 feet or more high. They are generally not cost - effective for cuts where soil must be excavated to allow placement of the reinforcement strips (geogrids). Geogrids are embedded in the compacted fill as the level of the fill is raised. The geogrids effectively stabilize a large mass of soil by developing friction between the grids and the soil and increasing the shear strength of the mass. The face of the reinforced fill may be nearly vertical if it is covered with architectural blocks which are integral G c o E n g i n e c r s File No. 0259 - 029 -R06 City of Tukwila February 8, 1995 Page 7 with the grids. If the face of the reinforced mass is left unfinished, it can be inclined more steeply than an unreinforced fill slope. Well- drained granular soils are best suited for use as fill when constructing a MSE geogrid system. The on -site soils contain a relatively high percentage of fines and will not be suitable for use in the reinfor.:ecl fill. For design of the MSE geogrid system, we recommend using a strength angle (phi) of 35 degrees for native undisturbed soils or structural fill compacted to at least 95 percent of the MDD. A drainage layer of crushed rock with less than 3 percent fines should be placed behind the wall and should extend at least 18 inches horizontally from the back of the wall blocks. A minimum embedment of 2 feet should be used for the wall blocks, assuming that the adjacent grade is level. If the adjacent grade is sloped, the wall should be additionally embedded until the face of the wall footing is at least 6 feet (horizontally) from the face of the slope. Wall footings bearing on undisturbed native soils or structural fill as described above can be designed using an average allowable bearing value of 2,500 psf with a maximum toe pressure of 3,500 psf, when the adjacent downhill slope is 41-1:1V or flatter. Passive resistance on the embedded portion of the wall should be assumed to be zero. Final design values for length and spacing of the grids should be specified by the geogrid system manufacturer. Based on our preliminary analysis for a Tcnsar type geogrid system, the grid length should be at least. 20 feet with a vertical spacing of 3 feet. The geogrid length and spacing should include an adequate factor of safety regarding overall stability. If requested, we can provide plans and specifications for the MSE geogrid system. CUT SLOPE RETAINING SYSTEMS In our opinion, a gravity block wall comprised of Keystone of Allan Block products, may satisfactorily protect the cut slopes along the uphill side of 51st Avenue South. The maximum height of the gravity block wall should be no more than 5 feet. The lowest course of blocks should be embedded at least 1 foot below the adjacent ground surface and supported by firm native soil. The block face should be constructed with a batter of 6H:1V. Perforated drainpipe having a diameter of at least 4 inches should be placed at the base of the wall along its entire length. This drainpipe should discharge into tightlines leading to appropriate collection and disposal systems. After each course of blocks are set, the wall should be backfilled with well- graded 1 -1/4 inch minus crushed rock. EROSION IMPACTS AND DRAINAGE CONSIDERATIONS Temporary Erosion Control and Drainage Measures The most effective methods of erosion control on construction sites include efficient surface water management, minimization of disturbed areas, erosion preventative slope covers, channel liners and energy dissipators for trenches, and diversion ditches or levees. Temporary erosion G c o E n g i n c e r s Filc No. 0259- 029 -R06 City of Tukwila February 8, 1995 Page 8 control measures should include proper control of surface water runoff, use of straw bale or appropriate geotextile filters and temporary sedimentation basins. New cut and fill slopes must be protected during wet weather to minimize slope erosion. Temporary protection could consist of plastic or membrane covers, or seeding combined with placement of a straw mulch. Erosion control programs should comply with local requirements and guidelines. Permanent Erosion Control and Drainage Measures All grading should be accomplished to avoid concentration of runoff onto or off unprotected cut or fill slopes, the roadway, or natural slopes. We recommend that drainage ditches or swales he constructed along the toes of permanent cuts and /or along the tops of slope support structures to control slope runoff onto the roadway. Open ditches or swales should be sloped less than 5 percent or should be lined with rock spalls or other suitable material to prevent erosion. Flow in ditches and swales should be routed to the roadway storm sewer system. All paved areas must be graded to prevent pavement runoff from flowing down adjacent slopes. We recommend that new cut and fill slopes and other areas where the vegetative cover has been removed be planted or seeded as soon as possible. As previously described, much of the site is underlain by relatively impermeable unweathered native silt. The silt soil unit tends to prevent the downward infiltration of precipitation, and therefore creates "perched" ground water conditions. It is very important that appropriate permanent drainage measures be provided for the project. In our opinion, an interceptor drain should be installed along the uphill shoulder to collect shallow ground water. The interceptor drain trench should extend 12 inches into the unweathered native silt estimated to be 2 to 4 feet deep. The trench width should be approximately 2 feet. We recommend that the trench be backfilled with medium to coarse sand and fine gravel containing Less than 3 percent fines. A 4- inch - diameter perforated, •smooth- walled pipe with cleanouts should be bedded on not less than 6 inches of the specified sand and gravel at the bottom of the trench. The pipe should be connected to the storm drain system. The perforated pipe should be sloped at not less than 1 percent. LIMITATIONS We have prepared this report for the City of Tukwila and members of their project team, for use in the design of a portion of this project. The data and report should be provided to prospective contractors for their bidding or estimating purposes only. Our report, conclusions and interpretations should not be construed as a warranty of the subsurface conditions. Variations in subsurface conditions are possible between the explorations and may also occur with time. A contingency'for unanticipated conditions should be included in the budget and schedule. Sufficient monitoring, testing and consultation should be provided by our firm during construction to confirm that the conditions encountered are consistent with those indicated G c o E n g i n c c r s File No. 0259- 029 -R06 City of Tukwila February 8, 1995 Page 9 by the explorations, to provide recommendations for design changes should the conditions revealed during the work differ from those anticipated, and to evaluate whether earthwork and foundation installation activities comply with contract plans and specifications. When the design is finalized, we recommend that the design and specifications be reviewed by our firm to see that our recommendations have been interpreted and implemented as intended. The scope of our services does not include services related to environmental remediation and construction safety precautions. 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. If there are any changes in the loads, grades, locations, configurations or type of facilities to be constructed, the conclusions and recommendations presented in this report may not be fully applicable. If such changes are made, we should be given the opportunity to review our recommendations and provide written modifications or verifications, as appropriate. 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 warranty or other conditions, express or implied, should be understood. We appreciate the opportunity to be of service to you on this project. Please call if you have questions concerning this report or if we can be of additional service. [EXPIRES 3/ii/ 9s t 13RB:GMD:vvl Document ID: 0259029.R2 Attachments Two copies submitted Yours very truly, GeoEngineers, Inc. Brian R. Beaman, P.E. Senior Geological Engineer «( ordon M. Denby, P.E. Principal GeoEngineers File No. 0259-029-R06 >CI le 135TH .j Al � / ST ST Ni la 1 —is ST 1 \ i f IJl1I61 ry. NI N 166.9h 144TH 1 SLVr7KArr `( 1. ` A+� ' PARK '" ‘\!.1...9----,:, • \15 `" T ) •w' NN▪ t ' S 1)9114 S S, sr x 4400 ST i 1-I is :` d. Pi 5o1 14219 ST �\ o • LIB Kl NI ' FOSTER •^ JR HS S •1 e 1 115 144TH ..• ST x •A s • s 0.1. T k O N N�a 1 1 t_..I50TNI ) (F �I S g• FS 1600 46TH ST J -11sJ� ;.-1 i a f ��(,�, ! i —148rN trt\i. 4 • ..—. ▪ 1200 3 7° '4� < ST S 1492-114.F S 15DTH ST 5 161St S •.2 ::SITE ST I H Q \ r U Y K; N J ' 154TH ' , S .1 FOSTER F�G1B GOLF LINKS \"9ti • 4'. .ni \? � I1 \ -7-4'1;:''' .11 3_L,I42lJ SI' 1 ill • I (fit 1 a " 144TH 1 I,ST I c, • nAZO.MIr 1 1.18 1 S 147 ti FS I 11 1� 1� I S 149TH 5 46 i r s. S 169•4 , ; S t = T� • 11' n 71111_11 $ 1 sH , s I 1 v^i 23 . 151ST ST ''''S ST I1tt 15214!14 i ' 1 s nr " g it = \ : ▪ S 152ND PL 1� 'D +� /\ •� ST '^ o S 153RD SO(//? �.� K 6100 wow F CH o 1 g�V ,4 1.1l-NM t A 0 138TH. NAL S 158TH ST S 1615 1— 1 % 1 1 . 1 INGTpY 1 Ml?1}\ •PARK Y • • CRYSTA SPRIN( PARK R CRESTYIEW ; y ` 161St sr S PARK S- 1� NDg. ST it S 16JW1 n } [ i 1-- 1 1�:P�— 1 a" I 1NMS1ce. ST > —S-166114 ST 27 5 167TH ST I • 168TH ST 1 in 9K4 Y [VMS BAKER 81. D STRANDER SOUINC£NTER P 26 S 1681 ST 1 172ND V 5'^ 172ND PL ST 0 2000 4000 SCALE IN FEET Reproduced with permission granted by THOMAS BROS. MAPS. This map is copyrighted by THOMAS BROS. MAPS. It is unlawful to copy or reproduce all or any part thereof, whether for personal use or resale. without permission. Geo Engineers VICINITY MAP FIGURE 1 w w z 4 W r w 6 SITE PLAN FIGURE 2 s*f /trg.Q.? ;oy;lv•r5i0 • • r ,•. . . • • - .. • • . „ . • "•;- ‘.• .4`17'.":Y+17;..:t.1•11:4 • ::_ - : • • • • • • • I • v • • V.4 • • Report C.3eotechnical Engineering Services 51st Avenue South Bridge Tukwila, Washington August 19, 1993 Replacement ' ..... • ''-' .'' . , '..:-. ..,'.:::':"..'..).;.:,!.....V.f.r.........'"::• i.'„,...,..,... '.',,' . , , .F.t7,■'.1.„:,!''.....'7f%,:,...,..T:'..',‘!.,;•:.,.;-,.,7.'.-.:'...f.'e:;";,..'f::`'.1.'r:::'!..:...,!,:':;...:-.,-.:::::''''''''''':'''''.....:;:1"?••• • . - . . . ,.i...„-,....,...,,,,,,..,....; ,..:.7.,,...-..,-,:: .,7,-;!.''.,...-..:-:-.:....., ...,.::',:4,.. •.r.:■-...:,.,"..;?5,!".,'S.',..-.'',--:aill,it;e44,s.,&,1'!:`,17."+” '-'-f .' 4. •.. '''''' -.,-,:,;:-.-?.--,;,.....::•....if5.•.::;-t,.z.v4:-/:,*---t.,:-,,c...',:;:i•Li-:,.,u 4,..-,;,--..,--i-,-,,,i.,..-...,..L....:. , • .,......-7.- ., ...;!-. .-.1.- ' , ...".....:: • -...C..'7'.i... • .• ,i....Z.-;••••=',”:)...c..,:...; :4;.^:0•;:it, ...•174P.”.i.';f:t.:'';'::?e,";■.4:4.'17.••.;tif:7i:•?.. --":' ....:i.._;'^' -•..\-.;:.7.:.,':'..fz.-7' '......,-.;-.......,:-...:i, .., . „ ,.......,; ,......„.., ....-;f. AY-2.:,-1,----t-,..(---',~.-,•-•i:.~..-iS‘:-:;.6.--u;.•• '-',4-..,•;4•:,.i:`:,..- . '. '''''' • '.t7"'''':;:".•.::''.'7.,•.;:f7,-.':',:..e;'• • • • NrV.fiWZI1 ••••■ ' • , - S.:44:— ,,.„. ., . , ,... t4..,iarr-iii'4.:1.47.?.::2;tz:';4..,',.T:-..‘„'F.'-'.- ,.,-,-....,-"-T.q:i4,•Yi:!.Cg4i'f'..‘fjtviAk`V;Z:f:. --. ..4..t.:r.ecs..i,%;:,...-,;.;;;;;..,?;-;..:z,'...,•,-,.,..',;,..4,1r.,,,3:1,:tiA:•.;41r..,41,At.h.,,,--s Arw...4.,A..,i;.:".,.. :. ‘ .,......, '..-,,,, , ,, ■;., '-;',::,:,,,.-.7:..''. ;'•',.'.'. w.. i• :!.. • ..f. --... • .... 7 . . -.- • ..- • .:,.:,,..-•.',..,,i;:•5:-.4--:•."0.,,r."..',;'„,.... . .. .. , .. - . ' -:`::'.:•.'.,..,'' r Ueol�Engineers August 19, 1993 Sargent Engineers, Inc. 320 West Bay Drive, Suite 101 Olympia, Washington 98502 Attention: Mr. Steve Roberts Geotechnical, Geoenvironmental and Geologic Services We are pleased to submit four copies of our "Report of Geotechnical Engineering Services, 51st Avenue South Bridge Replacement, Tukwila, Washington." The scope of services for this study is described in our revised proposal dated April 16, 1993. Preliminary results have been discussed with you as our findings were developed. It has been our pleasure to be of service to you on this project. If you have any questions regarding the contents of this report or if we can be of further service, please contact us. Yours very truly, GeoEngineers, Inc. 61 ordon M. Denby, P.E. Principal KPB:GMD:cros Document ID: 0259019.R GeoEngineers, Inc. 8410 154th Avenue N.E. Redmond, WA 98052 Telephone (206) 861 -6000 Fax (206) 861 -6050 CONTENTS Page No. INTRODUCTION 1 SCOPE 1 SITE DESCRIPTION 2 SURFACE CONDITIONS 2 SUBSURFACE CONDITIONS 2 CONCLUSIONS AND RECOMMENDATIONS 3 GENERAL 3 SITE PREPARATION 4 STRUCTURAL FILL, FILL SLOPES AND TEMPORARY EROSION CONTROL 4 EXCAVATION CONSIDERATIONS 5 BRIDGE SUPPORT 5 SCOUR CONSIDERATIONS 6 LATERAL EARTH PRESSURES 6 CONSTRUCTION CONSIDERATIONS 8 OBSERVATION OF CONSTRUCTION 8 LIMITATIONS 8 FIGURES Figure No. Vicinity Map 1 Site Plan 2 Generalized Cross Section A -A' 3 APPENDICES Page No. Appendix A - Subsurface Explorations and Laboratory Testing A -1 Subsurface Explorations A -1 Laboratory Testing A -1 APPENDIX A FIGURES Figure No. Soil Classification System A -1. Key to Boring Log Symbols A -2 Logs of Borings A -3 ... A -5 Direct Shear Test Data A -6 G e o E n g i n e e r s i File No. 0259 -019 - 806/081993 REPORT GEOTECHNICAL ENGINEERING SERVICES 51ST AVENUE SOUTH BRIDGE REPLACEMENT TUKWILA, WASHINGTON FOR CITY OF TUKWILA INTRODUCTION This report presents the results of our geotechnical engineering services for the planned 51st Avenue South bridge replacement in Tukwila, Washington. A vicinity map showing the location of the project site is presented in Figure 1. The existing bridge crosses over a ravine with a creek and over South 154th Street. The bridge consists of 5 spans with a total length of 205 feet and is composed of a concrete deck with steel girders supported on concrete column supports. The top of the existing bridge deck is about 40 feet above the bottom of the ravine and about 24 feet above South 154th Street. We understand that the replacement bridge will be situated at about the same elevation as the existing bridge and consist of a 222 - foot -long three -span structure. The south pier (abutment) footing will be situated at the same location as the existing abutment footing, the center pier situated near the bottom of the ravine, and the north pier situated about 25 feet north of the existing location. We understand that the abutment pier footings will be about 9.5 feet by 44 feet. The center pier footing will be about 28 feet by 29 feet. At this time, the proposed elevations for the bottom of the pier footings are Elevation 67 feet for the center pier and about Elevation 104 to 105 for the abutment piers. Wingwalls about 15 feet in length will be present on both sides of the new bridge. We understand that the wingwalls will support level backfill and be cantilevered off the abutment pier footings. Short approach slabs will be present at each end of the bridge. SCOPE The purpose of our services is to explore and evaluate the subsurface soil and ground water conditions as a basis for developing recommendations for the foundation design of the replace- ment bridge. Our specific scope of services includes the following: 1. Explore soil and ground water conditions at the proposed bridge location by drilling one test boring near each abutment and one test boring near the planned center pier location. 2. Perform laboratory tests on soil samples obtained from the explorations to evaluate pertinent properties and characteristics of the site soils. 3. Identify and evaluate foundation support options for the new bridge. 4. Provide allowable bearing values and estimated settlements for spread footing foundations. 5. Evaluate scour potential of the center pier. G e o E n g i n e e r s 1 File No. 0259 -019- R06/081993 6. Develop recommendations for design of abutment and wingwalls including lateral earth pressures for both static and seismic conditions, backfill and compaction criteria, and drainage considerations. 7. Evaluate potential construction problems and define any special considerations which are identified during the course of our study. 8. Attend one meeting with representatives of Sargent Engineers to discuss the results of our study. 9. Submit a written report presenting our findings and recommendations along with supporting field and laboratory data. SITE DESCRIPTION SURFACE CONDITIONS As shown in Figure 1, the site is situated northwest of the intersection of Interstate 5 and State Route 518 on the west valley wall of the Green River valley. The overall ground surface in the project area slopes generally down to the east. Topography at the bridge site is shown on Figure 2. The north -south trending bridge crosses a ravine with a shallow eastward flowing creek situated at an elevation of approximately 74 feet, or 40 feet below the top of the existing bridge deck. The bridge also crosses South 154th Street which is situated below the north end of the bridge at an elevation of approximately 90 feet, or 24 feet below the top of the existing bridge deck. In the bridge vicinity, the ravine slopes generally range from approximately 3H:1 V (horizontal to vertical) to 2H:1V, although small, locally steeper areas are present. The ravine is vegetated with scattered trees and dense undergrowth. It is likely that some fill was placed for the construction of South 154th Street. Grading has also occurred south of the existing bridge due to construction of State Route 518. SUBSURFACE CONDITIONS We explored subsurface soil and ground water conditions at the site by drilling one boring through the existing bridge deck near the planned center pier location to a depth of 30 feet below ground surface, and two borings near the north and south abutments to depths of 58.5 and 39 feet, respectively. The approximate locations of the borings are shown in Figure 2. A cross section showing generalized subsurface conditions is presented in Figure 3. A description of the borings, laboratory tests, and logs of the borings is presented in the appendix. Boring B -1, located near the planned center pier, encountered dense silty sand to a depth of 4.5 feet, underlain by dense gravel to a depth of approximately 7.5 feet. The gravel is underlain by hard silt with occasional fine sand lenses to the base of the boring at 30 feet. Boring B -2, located near the planned north abutment, encountered loose fill to a depth of approximately 2 feet. The fill consists of fine to medium sand with a trace of silt. The fill is underlain by loose weathered glacial till to a depth of approximately 5 feet. In the boring the G e o E n g i nee r s 2 File No. 0259 -019- R06/081993 weathered glacial till is underlain by very dense unweathered glacial till to a depth of approximately 16 feet. The weathered and unweathered glacial till consist of a silty fine to medium sand with fine to coarse gravel. The glacial till is underlain by hard to very dense interbedded silt and silty fine to medium sand and very dense silty fine to medium sand to a depth of 25 feet which in turn is underlain by medium dense to dense fine to medium sand with a trace of silt to a depth of approximately 40 feet. The sand is underlain by hard silt with fine to medium sand lenses to the base of the boring at 58.5 feet. Boring B -3, located near the planned south abutment, encountered medium dense fill to a depth of approximately 2.5 feet. The fill consists of fine to medium sand with a trace of silt. The fill is underlain by medium dense silty fine to medium sand with fine to coarse gravel to a depth of approximately 6 feet. Underlying the sand, boring B -3 encountered hard silt with fine to medium sand lenses to the base of the boring at 39 feet. Ground water was observed during drilling at depths of 4.5 and 17 feet below ground surface in borings B -1 and B -3, respectively. We measured the ground water level in a piezometer installed in boring B -2 at approximately 16.4 feet (Elevation 97.6 feet) below ground surface on July 9, 1993. Boring B -1 encountered a layer of relatively free - draining gravel overlying the silt. This layer may be hydraulically connected with the nearby creek. In general, ground water conditions at the site should be expected to fluctuate as a function of season, precipitation and other factors. CONCLUSIONS AND RECOMMENDATIONS GENERAL As discussed above, soil conditions encountered near the proposed abutment piers consist of up to approximately 6 feet of fill and loose to medium dense sand underlain by very dense glacial till at the north abutment and hard silt at the south abutment. In the vicinity of the proposed center pier, the hard silt is present at a depth of approximately 7.5 feet. Based on the anticipated loads for the new bridge, it is our opinion that the new bridge may be satisfactorily supported on conventional spread foundations. The north abutment footing may be supported by the very dense glacial till and the south abutment and center piers by the hard silt. At the time our explorations were completed, the ground water level was at about Elevation 72 feet in the vicinity of the planned center pier. In addition, our boring in this area encountered a gravel layer overlying hard silt and may be hydraulically connected to the creek. Therefore, we believe that some dewatering and /or shoring will be necessary in order to construct the center pier. Also, temporary shoring will likely be required along the north side of the center pier to avoid possible adverse impacts to the creek caused by construction activities. Recommendations for general site development, the design of spread foundations, the design of abutments and wingwalls are presented in the following sections. G e o E n g in e e r s 3 File No. 0259 -019- R06/081993 SITE PREPARATION Footing areas or areas to receive structural fill should be cleared of all debris and vegetation, and grubbed and stripped to a depth sufficient to remove topsoil and organic materials in general accordance with Section 2 -01 of the WSDOT Standard Specifications for Road, Bridge and Municipal Construction (WSDOT 1991). Existing pavements should be removed in accordance with Section 2 -02 of the Standard Specifications. Stripping depths should be determined based on field observations at the time of construction. Stripped materials should be disposed of off site or used for landscaping purposes. After stripping has been completed, the subgrade should be proofrolled, where accessible, with a loaded dump truck or similar heavy - wheeled construction equipment or, where inaccessible, probed to identify soft or loose zones. If soft or loose zones are identified, these areas should be compacted or excavated and replaced with compacted materials as recommended for structural fill. STRUCTURAL FILL, FILL SLOPES AND TEMPORARY EROSION CONTROL We recommend that the approach fills and center footing backfill be constructed using material which meets the criteria for gravel borrow as described in Section 9 -03.14 of the Standard Specifications. In addition to the criteria presented in Section 9- 03.14, the fill material should be free from organic material or other extraneous or objectional materials. If construction of the approach fills will occur during wet weather, we recommend that the percent passing the U.S. Standard No. 200 Sieve be less than about 5 percent. We recommend that structural fill for the approach fills be placed in lifts with a maximum uncompacted thickness of 8 to 10 inches and compacted to not less than 90 percent of the maximum dry density as determined by ASTM D -1557. Within 2 feet of pavement subgrades, structural fill should be compacted to at least 95 percent of the maximum dry density. We recommend that all backfill placed around the center or abutment piers be compacted to at least 95 percent of the maximum dry density. These compaction criteria achieve a higher density than those described in the Standard Specifications (Section 2- 03.3[14]D). We recommend that the specifications for fill compaction on this project refer to ASTM D -1557 rather than to the control tests indicated in the Standard Specifications. New approach fil'.s should be keyed into the existing approach slopes by terracing as specified in Section 2- 03.0(14). Fill slopes should not exceed 2H:1V. Slopes should be hydroseeded and mulched as soon as possible after the approach fills are constructed. Temporary erosion control measures may be necessary until permanent vegetation is established. Curbs or berms should be constructed along the tops of fill slopes to intercept surface water and prevent water from flowing down the slopes. G e o E n g i nee r s 4 File No. 0259-019-R06/081993 EXCAVATION CONSIDERATIONS We anticipate that the excavations required for construction of the footings will range from 10 to 15 feet in depth. We recommend that the contractor have primary responsibility for the decision on whether to use open cut slopes or shoring. All excavated slopes should be outside a 45 degree envelope extending down and outward from existing foundations or utilities. Temporary slopes which expose medium dense to dense material may be sloped at 1H:1V provided there is no sloughing or seepage from the slope face. Excavations exposing loose materials or below the ground water table will likely need to be cut at a flatter slope to minimize sloughing or ravelling of the cut faces. Alternatively, temporary shoring can be used to support the excavation side walls. At the time our field explorations were accomplished, the ground water table was at about Elevation 72 feet near the proposed center pier location. The elevation of the water table during construction will depend in part on the time of year the construction is accomplished, precipitation and the water level in the adjacent creek. We anticipate that dewatering will be necessary during construction of the center pier. We expect that either sheet pile shoring in combination with shallow sump pumps, or use of well points or wells will be necessary to adequately dewater the center pier excavation. Alternatively, the contractor may choose to shore the creek side walls while open- cutting the remainder of the excavation. The scope of our services does not include a hydrogeological study of the site. If the up -slope portion of the center pier excavation is open -cut, significant ground water seepage may be encountered and the contractor must be prepared to deal with this water. We recommend that design of the shoring and dewatering system be made the responsibility of the contractor. BRIDGE SUPPORT We recommend that the center pier footing be founded on the native hard silt. This material was encountered at an elevation of about 68 feet in boring B -1. We recommend that the north abutment footing be founded on very dense unweathered glacial till, and the south abutment footing be founded on hard silt. The unweathered glacial till and silt were encountered at elevations of about 108 and 111 feet in borings B -2 (north) and B- 3(south), respectively. Therefore, at the current proposed pier footing elevations, we anticipate that suitable bearing material will be exposed. We recommend that all footing excavations be examined by a qualified individual to determine that suitable bearing soils have been exposed. Care must be taken in preparing the subgrade for the footings to avoid disturbance of the bearing materials. Any seepage in the footings should be collected and removed immediately to prevent softening of the subgrade. All soft, loose or disturbed material should be removed from the footing excavations before pouring concrete. We recommend that, die bearing surface be protected immediately after examination by placing a lean concrete mud mat or a 6 -inch layer of free- draining gravel. GeoEnginecrs 5 File No. 0259 -019 -R06 .'081993 Although boulders were not encountered in any explorations, we anticipate that occasional boulders may be present in the glacial till. Therefore, boulders may be present within the footing excavation at the north abutment. If boulders are encountered in the bottom of the excavation, they should be removed so that the base of the footing is not in point contact with the boulder. The boulder excavation cavity should be backfilled with gravel borrow compacted to the standards given above for structural fill. We recommend that all spread footings have a minimum depth of embedment of 18 inches below the lowest adjacent finished grade for frost protection. For footings placed within embankment slopes, the allowable bearing pressures presented in this report assume that these slopes will be sloped no steeper than 2H:1V, and that the footings will have a minimum setback of one footing width or 6 feet, whichever is greater, measured horizontally from the face of the footing to the nearest point on the adjacent slope. We understand that the abutment and center pier footings will be about 9.5 and 28 feet in width, respectively. For these widths and assuming the footings are constructed in accordance with our recommendations, the footings may be designed using an allowable soil bearing pressure of 10,000 psf (pounds per square foot) for the total of dead and long -term live loads. This bearing pressure may be increased by up to one -third for short-term loads such as wind or seismic loading conditions. We estimate that the settlement of footings designed and constructed in accordance with our recommendations will be less than 1 inch. Most of these settlements are expected to occur rapidly as loads are applied. SCOUR CONSIDERATIONS At this time, we do not know if the water flows in the existing creek increase significantly in response to changes in precipitation. During our study, we observed a low volume of water flowing in the creek. We also observed no evidence of active downcutting or incision of the existing creek channel nor armour protection along the banks. In addition, the center pier will be founded on glacially consolidated silt, which is relatively resistant to erosion and downcutting. Based on this information and provided the center pier is founded on the existing hard silt, we do not see the need for scour protection. However, backfill placed around the center pier will likely be susceptible to scour. Therefore, we recommend that the top 18 inches of backfill around the center pier consist of quarry spalls which range from 6 to 12 inches in dimension. LATERAL EARTH PRESSURES The lateral soil pressures acting on conventional reinforced concrete retaining walls will be a function of the amount of lateral wall movement which can occur as backfill is placed. For walls that are free to yield at the top at least one - thousandth of the height of the wall, soil pressures will be less than if movement is limited by such factors as wall stiffness or bracing. G e o E n g i n e e r s 6 File No. 0259 -019- R06/081993 Approach and wingwalls should be designed for static active earth pressures based on an equivalent fluid density of 35 pcf (pounds per cubic foot). This value is based on the assumption that (1) the approach and wingwalls will not be restrained against rotation when the backfill is placed, (2) the backfill surface is level, (3) the backfill consists of imported granular materials, and (4) the backfill is fully drained. If the approach and wings walls will be restrained against rotation during backfilling, they should be designed for an at -rest earth pressure of 55 pcf. The above - recommended lateral soil pressures do not include the effects of surcharges such as traffic loads or other surface loads. Surcharge effects should be considered as appropriate. WSDOT currently uses AASHTO's: "Guide Specifications for Seismic Design of Highway Bridges . . . 1983" (ATC -6) to develop dynamic lateral pressures on abutment walls. . We recommend that the abutment walls be designed for a rectangular pressure distribution of 7H -psf, where H is the height of the wall in feet. This distribution should be in addition to the triangular pressure distributions recommended for static conditions. A design horizontal acceleration of 0.2g, where g is the gravitational acceleration, and no vertical acceleration was assumed in the development of our recommendations for lateral pressure. We recommend that wall backfill and drainage be in general accordance with Section 6- 02.3(22) of the Standard Specifications. However, we recommend that the compaction standard be changed from that specified in Section 6- 02.3(22) to reduce the potential for increased lateral earth pressures on the walls. We recommend that fill placed within a horizontal distance equal to half of the height of the walls be compacted to approximately 92 percent of the maximum dry density as determined by ASTM D -1557. The upper 2 feet of fill should be compacted to 95 percent to provide adequate support for the approach slabs. The contractor should avoid overcompaction of the backfill so that damage to the walls does not occur. Resistance to lateral wall loads can be developed both through friction on the base and passive pressure on the embedded portion of walls and footings. Friction resistance on the base of the footing may be computed using a coefficient of friction of 0.5 applied to dead load forces. If the backfill material within the passive zone will receive only minimal compaction, we recommend that the passive soil pressures be computed using an equivalent fluid density of 300 and 130 pcf for a level backfill surface and a backfill surface inclined at 2H:1V below the horizontal, respectively. If the backfill within the passive zone is compacted to at least 95 percent of the maximum dry density in accordance with ASTM D -1557, passive soil pressures may be computed using equivalent fluid density values of 450 and 250 pcf for a level backfill surface and a backfill surface inclined at 2H:1V below the horizontal, respectively. The above passive pressures are for drained soil conditions. For backfill below the water table, we recommend allowable passive soil pressures equal to one -half of the above presented values. The above coefficient of friction and passive equivalent fluid density values are based on a factor of safety of 1.0. G e o E n g i n e e r s 7 File No. 0259 -019- R06/081993 CONSTRUCTION CONSIDERATIONS The primary construction consideration is construction of the center pier, as discussed in "Excavation Considerations." First, the center pier will be situated very close to the existing stream, and sheet piles or other shoring measures will be necessary to minimize the construction impacting the stream and the stream flow from impacting the footing excavation. Second, the center pier will require a cut on the order of 10 to 15 feet on the south side. If accomplished as an open cut, variable amounts of seepage will likely be encountered on the cut face. The contractor must be prepared to deal with this water. In addition, loose material may be present on the slope surface, requiring a flatter temporary cut slope or shoring. Areas in the vicinity of the existing bridge have been modified in the past during construction of SR 518 and South 154th Street. Greater depths of fill than we encountered in our borings may be encountered during excavation for the pier footings. If greater depths of fill are encountered, we should be consulted to provide additional recommendations, as appropriate. At this time, we do not know if construction of the new pier footings will impact existing utilities. As described above, excavations should be accomplished in such a manner that utilities will not be disturbed, or the utilities should be temporarily supported during construction. OBSERVATION OF CONSTRUCTION Satisfactory foundation and earthwork performance depends, to a large degree, on quality of construction. Sufficient monitoring of the contractor's activities is a key part of determining that the work is completed in accordance with the construction drawings and specifications. We recommend that GeoEngineers be retained to observe footing excavations and general fill placement, and to review laboratory compaction and field moisture - density information. Subsurface conditions observed during construction should be compared with those encountered during the subsurface exploration. Recognition of different conditions often requires experience; therefore, qualified personnel should visit the site with sufficient frequency to detect if subsurface conditions differ significantly from those anticipated. LIMITATIONS We have prepared this report for use by the City of Tukwila and Sargent Engineers in the design of a portion of the 51st Avenue South Bridge Replacement Project. The data and report can be utilized for bidding or estimating purposes, but our report, conclusions, and interpretations should not be construed as a warranty of the subsurface conditions. Complete site development plans and design details were not known at the time of preparation of this report. As your design develops, we expect that additional consultation may be necessary to provide for modification or adaptation of our recommendations. When the design has been finalized, we recommend that the final design drawings and specifications be reviewed by our firm to see that our recommendations have been interpreted and implemented as intended. G e oE n g i n e e r s 8 File No. 0259 -019- R06s081993 Our scope 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 explorations and also with time. A contingency for unanticipated conditions should be included in the budget and schedule. We recommend our firm be retained to provide sufficient monitoring, testing and consultation 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 comply with the 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 conditions, express or implied, should be understood. 4 O ► We appreciate the opportunity to work with you on this project. If you have questions concerning this report or if we can provide additional services, please call. FET:PIRES 3 KPII:NLT:GMD:cros Document ID: 0259019.R J/ Yours very truly, GeoEngineers, Inc. Karen Billica Senior Staff Engineer d44-4 Nancy L. Tochko, P.E. Senior Engineer ady ordon M. Denby, P.E. Principal G e o E n g i n e e r s 9 File No. 0259 -019- R06/081993 026,.0/9'0(. A'f6:43L'9 7703 ^ �' .-'----~- Reference: USGS 7.5' topographic quadrangle map 'Des Moines, Wash.,* photorevised 1973. A 120- 100- 7 28 -7 c Medium dense sand (fill) 58- 59- (07/09/93) 5018•- 50/5"- 50/8' 50/8•- HORIZONTAL AND VERTICAL SCALE: 1"=20' Notes: 1. The topography is based on a topographic map supplied by Sargent Engineers Inc. 2. The subsurface conditions shown are based on interpolation between widely spaced explorations and should be considered approximate. 3. Location of cross section is shown on Figure 2. Planned Bridge Existing Bridge co w u. 1-6 I 0 CO 38 - 89 50/V- 50/V- 50/8•- 50/5'- Planned Central Pier Location Creek Dense gravel with sand - (07/67/93) 7 • • • ? • South 154th Str FiII 9 Hard silt with sand lenses EXPL 3 Geo E Planned Bridge Existing Bridge Planned Central Pier Location -- Creek Dense gravel with sand Is mate. 38- _ "'07/07/93) 50/5' - 50/5' - 50/6' - 50/5'- Interbedded hard/ very dense silt and silly sand South 154th Street Hard silt with sand lenses T Loose silty sand with gravel (weathered till)1 6- Loose sand (fill) 82/8' - Very dense silty sand with gravel sow- (glacial till) , ' - -� x_'(07/09/93 —? Medium dense to dense silty sand with gravel - Medium dense to dense sand EXPLANATION: BORING WATER LEVEL ON DATE NOTED SAMPLE BLOW COUNT z 61- 26- 38- 28 70- 50/5• - 50/6' - 50/6'- 120 -100 u- `8 W 40 Geoff Engineers GENERALIZED CROSS SECTION A - A' FIGURE 3 0 0 • t• . rn ...1_I. I.: 1 1 .1 • 1 •�I 1 • F- —r-F- 1 I----t- t Existing .Bridge.' 1. L_ _ J 1 1 1 • to be removed. • LL-4-8 -'1.7, 1 1 1 i ••�' 1 ... • I I .1 •1' 1 1 I• ' 1 1 1 1.• 1. 154th ; 0 EXPLANATION: 0 co • BORING GENERALIZED CROSS SECTION • • Rotor :,1•541111' rntfil Od (+it +n onllllod '5 Ist Avenue South Bridge Over 154th Street - Bridge N.' by City of Tukwila Department of Public Works. 0 • CO Geo \OEngini reet — Bridge ' 0 8 20 40 SCALE IN FEET Geo Engineers SITE PLAN FIGURE 2 APPENDIX A SUBSURFACE EXPLORATIONS AND LABORATORY TESTING SUBSURFACE EXPLORATIONS Subsurface soil and ground water conditions along the project alignment were explored by drilling three borings at the locations shown in Figure 2. The borings were drilled to depths ranging from 30 to 58.5 feet below existing ground surface using a truck- mounted hollow -stem auger drill. Relatively undisturbed samples were obtained from the borings using a Dames & Moore 2.4- inch - inside - diameter split- barrel sampler. The sampler was driven 18 inches by a 300 -pound weight falling a vertical distance of approximately 30 inches. The number of blows required to drive the sampler the last 12 inches, or other indicated distance, is recorded on the boring logs. A geotechnical engineer with our firm continuously monitored the explorations and maintained detailed logs of the soil and ground water conditions encountered. Soils encountered were classified in general accordance with the classification system described in Figure A -1. A key to the symbols used on the boring logs is presented in Figure A -2. Logs of the explorations are presented in Figures A -3 through A -5. The boring logs are based on our interpretation of the field and laboratory data and indicate the various types of soils encountered. They also indicate the depths at which these soils or their characteristics change, although the change may actually be gradual. If the change occurred between samples, it was interpreted. A piezometer was installed in boring B -2 for monitoring ground water conditions. The piezometer, which extends to a depth of 40 feet, consists of 3/4-inch-diameter Schedule 40 PVC pipe with a 2- foot -long, 2- inch - diameter slotted section of PVC pipe at the bottom. The annular space around the slotted portion of pipe was backfilled with clean medium sand, and a bentonite seal was installed between depths of about 33 and 35 feet. The remaining annular space was backfilled with a mixture of cuttings and bentonite chips. A steel flush monument was installed at the surface. LABORATORY TESTING The soil samples obtained from the borings were examined and tested in our laboratory to evaluate pertinent physical characteristics and to develop data for design recommendations. The testing program included moisture, density and direct shear tests. Moisture and density determinations were made on selected samples for correlation purposes. The results of these determinations are presented to the left of the corresponding samples notations on the boring logs and on figures presenting the results of other laboratory tests. Strength characteristics of the soils were evaluated by perfonning direct shear tests on two samples. The results of the direct shear tests are presented in Figure A -6. G e o E n g i n e e r s A - 1 File No. 0259 -019- R06/081993 GE! 85 -85 Rev. 05/93 SOIL CLASSIFICATION SYSTEM MAJOR DIVISIONS GROUP SYMBOL GROUP NAME COARSE GRAINED SOILS More Than 50% Retained on No. 200 Sieve GRAVEL More Than 50% of Coarse Fraction Retained on No. 4 Sieve CLEAN GRAVEL GW WELL- GRADED GRAVEL, FINE TO COARSE GRAVEL GP POORLY- GRADED GRAVEL GRAVEL WITH FINES GM SILTY GRAVEL GC CLAYEY GRAVEL SAND More Than 50% of Coarse Fraction Passes No. 4 Sieve CLEAN SAND SW WELL- GRADED SAND, FINE TO COARSE SAND SP POORLY - GRADED SAND SAND WITH FINES SM SILTY SAND SC CLAYEY SAND FINE GRAINED SOILS More Than 50% Passes No. 200 Sieve SILT AND CLAY Liquid Limit Less Than 50 • INORGANIC ML SILT CL CLAY ORGANIC OL ORGANIC SILT, ORGANIC CLAY SILT AND CLAY Liquid Limit 50 or More INORGANIC MH SILT OF HIGH PLASTICITY, ELASTIC SILT CH CLAY OF HIGH PLASTICITY, FAT CLAY ORGANIC OH ORGANIC CLAY, ORGANIC SILT HIGHLY ORGANIC SOILS PT PEAT NOTES: SOIL MOISTURE MODIFIERS: 1. Field classification is based on visual examination of soil Dry - Absence of moisture, dusty, dry to the touch in general accordance with ASTM D2488 -90. Moist - Damp, but no visible water 2. Soil classification using laboratory tests is based on ASTM D2487.90. Wet - Visible free water or saturated, usually soil is obtained from below water table 3. Descriptions of soil density or consistency are based on interpretation of blow count data, visual appearance of soils, and /or test data. - -.jit, Geo ,O Engineers SOIL CLASSIFICATION SYSTEM FIGURE A -1 GB 86 -88 Rev. 6/90 LABORATORY TESTS: SOIL GRAPH: AL CP CS DS GS %F HA SK SM MD SP TX UC CA Atterberg limits Compaction Consolidation Direct shear Grain - size Percent fines Hydrometer analysis Permeability Moisture content Moisture and density Swelling pressure Triaxial compression Unconfined compression Chemical analysis BLOW- COUNT /SAMPLE DATA: Blows required to drive a 2.4 -inch I.D. split - barrel sampler 12 inches or other indicated distances using a 300 -pound hammer falling 30 inches. Blows required to drive a 1.5 -inch I.D. (SPT) split - barrel sampler 12 inches or other indicated distances using 140 -pound hammer falling 30 inches. "P" indicates sampler pushed with weight of hammer or against weight of drill rig. SM Soil Group Symbol (See Note 2) Distinct Contact Between Soil Strata Gradual or Approximate Location of Change Between Soil Strata 2 Water Level Bottom of Boring 22 ■ Location of relatively undisturbed sample 12 ® Location of disturbed sample 17 p Location of sampling attempt with no recovery 10 0 Location of sample obtained in general accordance with Standard Penetration Test (ASTM D -1586) procedures 26 m Location of SPT sampling attempt with no recovery Location of grab sample NOTES: 1. The reader must refer to the discussion in the report text, the Key to Boring Log Symbols and the exploration logs for a proper understanding of subsurface conditions. 2. Soil classification system is summarized in Figure A -1. Geo ,p) Engineers KEY TO BORING LOG SYMBOLS FIGURE A -2 eo N N 2 0259. 019 -R06 0 TEST DATA Moisture Dry Content Density Lab Tests ( %) (pc() COL) N 0 • Group Symbol BORING B -1 DESCRIPTION Surface Elevation (ft.) : 76.0 5— MD 25 101 10— MD 26 100 15— w W u- Z _ 2 MD, 23 107 p 20 — DS MD 25 100 25 — 30 — 35 — 38 1 69 1 50/5" 1 50/5" 50/6" 1 50/5" 1 ,0 SM Brown silty fine to medium sand with fine to coarse gravel (dense, moist) GW— Gray fine to coarse gravel with fine to medium sand, silt and GM occasional organic matter (dense, wet) ML Gray silt with occasional fine sand lenses (hard, moist) Boring completed at 30.0 feet on 07/07/93 Ground water encountered at 4.5 feet while drilling 0 —5 —10 —15 — 20 — 25 — 30 —35 40 — —40 Note: See Figure A -2 for explanation of symbols Geo ,,,Engineers LOG OF BORING FIGURE A -3 :KBP:GMD :vw 7/26/93 0259 - 019 -RO6 TEST DATA Moisture Dry o 9 Content Density ° Lab Tests ( %) (pcf) 6 Group h Symbol BORING B -2 DESCRIPTION Surface Elevation (ft.) : 114.0 5— 10 — 15 -- 1- w w - u. z - F- - w p 20—' 25 -7 30 — 35 — 40 — MD 10 104 MD 8 127 MD 18 112 MD 18 114 62/6" 50/6" 48 61 26 36 26 ❑ SP Brown fine to medium sand with a trace of silt (loose, moist) (fill) SM Brown silty fine to medium sand with occasional fine to coarse gravel and organic matter (loose, moist) (weathered till) SM Brown orange stained silty fine to medium sand with fine to coarse gravel (very dense, moist) (glacial till) • • ML Interbedded brown silt and silty fine to medium sand (hard /very • • SM dense, moist) SM Brown silty fine to medium sand (very dense, moist to wet) SP Brown fine to medium sand with a trace of silt (medium dense to dense, wet) Note: See Figure A -2 for explanation of symbols —5 —10 —15 —20 — 25 — 30 —35 —40 Geo ,,-<; Engineers LOG OF BORING FIGURE A -4a 0259-019-R06 DEPTH IN FEET TEST DATA Moisture Content 40 Lab Testa ( %) 45 — 50 — 55 — 60 — 65 — 70 — 75 — 80 — Dry o' Density aa° (pcf) e • Group Symbol BORING B -2 (Continued) DESCRIPTION MD 24 102 MD 27 97 70 50/5" 50/6" 1 50/6" 40 ML Gray silt with fine to medium sand lenses (hard, moist) —45 ML Interbedded gray silt and silty fine to medium sand with fine to SM coarse gravel (hard /very dense, moist) —50 ML Gray silt with fine to medium sand lenses (hard, moist) Note: Sec Figure A -2 for explanation of symbols —.55 Boring completed at 58.5 feet on 07/08/93 Piczomcter installed to 40.0 feet Ground water measured at a depth of 16.4 feet on 07/09/93 — 60 —65 —70 —75 —80 Geo Engineers LOG OF BORING FIGURE A -4 b :KBP:GMD:vvv 7/26/93 0259. 019 -R06 TEST DATA BORING B -3 Moisture Dry c Content Density . 0 Lab Testa ( %) (pet) N N" Group Symbol 5— 10— 15— w w w— w Z_ — 1-- — p 20 — 25 — 30 — 35 — h0 — MD 10 116 MD 21 107 MD, DS 23 103 MD 21 108 MD 20 109 28 56 59 79 50/6" 1 50/5" 1 50/6" 50/6" DESCRIPTION Surface Elevation (ft.) : 117.0 SP Gray orange stained fine to medium sand with a trace of silt (medium dense, moist) (fill) SM Brown silty fine to medium sand with fine to coarse gravel and occasional organic matter (medium dense, moist) ML Brown orange stained silt with fine to medium sand lenses (hard, moist) Note: See Figure A -2 for explanation of symbols Becomes gray Boring completed at 39.0 feet on 07/09/93 Ground water encountered at 17.0 feet while drilling —5 —10 —15 — 20 — 25 —30 —35 — 40 Geo Engineers LOG OF BORING FIGURE A -5 DIRECT SHEAR TEST DATA Boring Number Depth of Sample (feet) • Sample Description Moisture Content ( %) Dry Density (pcf) Normal Pressure (psf) Peak Strength (psf) • B -3 13 Gray silt (ML) 23 103 2,000 2,078 B -1 19 Gray silt (ML) 23 107 4,000 4,103 *All tests performed on submerged samples at a shear rate of 0.04 inches per minute. Geo Engineers DIRECT SHEAR TEST DATA FIGURE A -6 ontrol No. Epic File No. —' 0i Fee: $325 Receipt No. ENVIRONMENTAL CHECKLIST A. BACKGROUND 1. Name of proposed project, if applicable: 51 Ave S (S 154) Bridge Replacement 2. Name of applicant: City of Tukwila 3. Address and phone number of applicant and contact person: 6300 Southcenter Blvd., Suite 100 Tukwila, WA 98188 433 -0179; Ross Heller 4. Date checklist prepared: 11/2/94 5. Agency requesting checklist City of Tukwila 6. Proposed timing or schedule (including phasing, if applicable): Construction is planned to begin in second quarter of 1995, and continue into 1996. 7. Do you have any plans for future additions, expansion, or further activity related to or connected with this proposal? If yes, explain. No. 8. List any environmental information you know about that has been prepared, or will be prepared, directly related to this proposal. This checklist. 9. Do you kn ow whether applications are pending for governmental approvals of other proposals directly affecting the property covered by your proposal? If yes, explain. No. Page 1 ENVIRONMENTAL CHECKLIST 10. List any government approvals or permits that will be needed for your proposal. Authorization by Tukwila City Council and approval of Tukwila City Mayor. An HPA from the Department of Fisheries will be required for the work in Gilliam Creek. 11. Give brief, complete description of your proposal, including the proposed uses and the size of the project and site. There are several questions later in this checklist that ask you to describe certain aspects of your proposal. You do not need to repeat those answers on this page. Section E requires a complete description of the objectives and alternates of your proposal and should not be summarized here. The existing 51 Ave S Bridge will be removed, and a new one errected. The new bridge will carry the same number of lanes, but will be slightly wider and will carry sidewalks. The vertical alignment of the north approach roadway will be smoothed out to improve the site distance. 12. Location of the proposal. Give sufficient information for a person to understand the precise location of your proposed project, including a street address, if any, and section, township, and range, if known. If a proposal would occur over a range of area, provide the range or boundaries of the site(s). Provide a legal description, site plan, vicinity map, and topographic map, if reasonably. available. While you should submit any plans required by the agency, you are not required to duplicate maps or detailed plans submitted with any permit applications related to this checklist. The project is located in the City of Tukwila, along 51 Ave S, over S 154 Street. The Bridge is in section 22 and 23, Township 23 North, Range 4 East, W.M., City of Tukwila, King County Washington. 13. Does the proposal lie within an area designated on the City's Comprehensive Land Use Policy Plan Map as environmentally sensitive? The bridge spans a stream, and there are steep slopes at each end. Page 2 ENVIRONMENTAL CH1 :LIST B. ENVIRONMENTAL ELEMENTS 1. Earth a. General description of the site (circle one): Flat, rolling, hilly, steep slopes, mountainous, other ,The terrain is steep. b. What is the steepest slope on the site (approximate percent slope)? The maximum slope is approximately 70 %. c. What general types of soils are found on the site (for example, clay, sand, gravel, peat, muck)? If you know the classification of agricultural soils, specify them and note any prime farmland. The foundation soils are glacially consolidated sand & silt. GeoEngineers will complete boarings to confirm foundation design. d. Are there surface indications or history of unstable soils in the immediate vicinity? If so, describe. Some areas of bank erosion exist. e. Describe the purpose, type, and approximate quantities of any filling or grading proposed. Indicate source of fill. Cuts and fills will be made to accommodate the new bridge. Unsupported slopes will be limited to 1.5:1 maximum. In areas where the slope cannot be maintained, retaining walls will be used. Approximately 3,000 yards of gravel and gravel borrow will be imported. f. Could erosion occur as a result of clearing, construction,or use? If so, generally describe. Some erosion could result from the site preparation, including clearing and grubbing. Temporary erosion control techniques will limit this to a minimum. g. About what percent of the site will be covered with impervious surfaces after project construction (for example, asphalt or buildings)? Approximately 80% of the site (R /W) will be asphalt or concrete. Page 3 ENVIRONMENTAL CHECKLIST h. Proposed measures to reduce or control erosion, or other impacts to the earth, if any: Temporary erosion control will be employed during construction as required. Following construction, the site will be either impervious or vegetated. • 2. Air a. What types of emissions to the air would result froin the proposal (i.e., dust, automobile odors, industrial wood smoke) during construction and when the project is completed? If any, generally describe and give approximate quantities if known. There will be dust and exhaust emissions during construction. Exhaust emissions along this street are not expected to increase as the result of this project. b. Are there any off -site sources of emissions or odor that may affect your proposal? If so, generally describe. No c. Proposed measures to reduce or control emissions or other impacts to air, if any: Water trucks will be used as standard dust suppression during construction. 3. Water a. Surface: 1) Is there any surface water body on or in the immediate vicinity of the site (including year -round and seasonal streams, saltwater, lakes, ponds, wetlands)? If yes, describe type and provide names. If appropriate, state what stream or river it flows into. Gilliam Creek passes under the bridge. Page 4 ENVIRONMENTAL C :LIST 2) Will the project require any work over, in, or adjacent to (within 200 feet) the described waters? If yes, please describe and attach available plans. Yes, the foundation for the center 'V' pier will be under the stream. Plans are attached. 3) Estimate the amount of fill and dredge material that would be placed in or removed from surface water or wetlands and indicate the area of the site that would be affected. Indicate the source of fill material. The stream will be temporarlily relocated to accomodate construction of the center pier foundation. The stream will be restored. 4) Will the proposal require surface water withdrawals or diversions? Give general description, purpose, and approximate quantities, if known. Gilliam Creek will be diverted during construction only. 5) Does the proposal lie within a 100 -year floodplain? If so, note location on the site plan. No. 6) Does the proposal involve any discharges of waste materials to surface waters? If so, describe the type of waste and anticipated volume of discharge. No. Page 5 ENVIRONMENTAL CHECICOST b. Ground: 1) Will ground water be withdrawn, or will water be discharged to ground water? Give general description, purpose, and approximate quantities, if known. No. 2) Describe waste materials that will be discharged into the ground from septic tanks or other sources, if any (for example: Domestic sewage; industrial, containing the following chemicals...; agricultural; etc.) Describe the general size of the system, the number of such systems, the number of houses to be served (if applicable), or the number of animals or humans the system(s) are expected to serve. None. c. Water Runoff (including storm water): 1) Describe the source of runoff (including storm water) and method of collection and disposal, if any (include quantities, if known). Where will this water flow? Will this water flow into other waters? If so, describe. The source of the runoff will be from the roadway. Pipes, ditches, swales and natural water courses will all be utilized as required design components to convey storm water. Page 6 ENVIRONMENTAL CHIC :LIST, 2) Could waste materials enter ground or surface waters? If so, generally describe. Runoff from the existing roadway is likely to contain automobile oils and fuel - this project will not increase the level of waste materials entering ground or surface waters. d. Proposed measures to reduce or control surface, ground, and runoff water impacts, if any: A storm -water drainage system that meets King County Design Standards is proposed. 4. Plants a. Check or circle types of vegetation found on the site: X deciduous tree: alder, maple, aspen, other X evergreen tree: fir, cedar,pine, other X shrubs X grass pasture crop or grain X (some) wet soil plants: cattail, buttercup, bulrush, skunk cabbage, other X water plants: water lily, eel grass, milfoil, other other types of vegetation b. What kind and amount of vegetation will be removed or altered? In areas where the roadway is widened beyond the existing graveled shoulder; trees, brush and grass will be removed to accommodate the street section. c. List threatened or endangered species known to be on or near the site. None known. Page 7 ENVIRONMENTAL CHECILST d. Proposed landscaping, use of native plants, or other measures to preserve or enhance vegetation on the site, if any: Property restoration can include seeding and planting of trees and shrubs. 5. Animals a. Circle any birds or animals which have been observed on or near the site or are known to be on or near the site: Birds:. hawk, songbirds, migratory water fowl, other: Mammals: raccoons, squirrels, small rodents, other: Fish: bass, salmon, trout, herring, shellfish, other: Other: b. List any threatened or endangered species known to be on or near the site. None known. c. Is the site part of a migration route? If so, explain. No. d. Proposed measures to preserve or enhance wildlife, if any: None proposed. Page 8 ENVIRONMENTAL CHI :LIST 6. Energy and Natural Resources a. What kinds of energy (electric, natural gas, oil, wood stove, solar) will be used to meet the completed project's energy needs? Describe whether it will be used for heating, manufacturing, etc. Electric street lighting will be used. b. Would your project affect the potential use of solar energy by adjacent properties? If so, generally describe. No. c. What kinds of energy conservation features are included in the plans of this proposal? List other proposed measures to reduce or control energy impacts, if any: The project will replace mercury vapor lights with efficient high pressure sodium luminaires. 7. Environmental Health a. Are there any environmental health hazards, including exposure to toxic chemicals, risk of fire and explosion, spill, or hazardous waste, that could occur as a result of this proposal? If so, describe. No. 1) Describe special emergency services that might be required. None. 2) Proposed measures to reduce or control environmental health hazards, if any: Not applicable. Page 9 ENVIRONMENTAL CHEC -1ST b. Noise 1) What types of noise exist in the area which may affect your project (for example: traffic, equipment, operation, other)? Not applicable. What types and levels of noise would be created by or associated with the project on a short -term or long -term basis (for example: traffic, construction, operation, other)? Indicate what hours noise would come from the site. Noise generated by the construction equipment will occur on a short term basis. 3) Proposed measures to reduce or control noise impacts, if any: Restrict hours of operation to comply with the City's noise ordinance. 8. Land and Shoreline Use a. What is the current use of the site and adjacent properties? The site is currently a two -lane paved roadway & bridge. b. Has the site been used for agriculture? If so, describe. No. c. Describe any structures on the site. The existing bridge carries 2 lanes and spans over 200'.. Page 10 ENVIRONMENTAL CHI "LI T d. Will any structures be demolished? If so, what? Yes, the existing bridge. e. What is the current zoning classification of the site? The adjacent properties vary from R -3 to C -2. f. What is the current comprehensive plan designation of the site? The plan designation for the adjacent properties varies from medium density residential to commercial. g. If applicable, what is the current shoreline master program designation of the site? Not applicable. h. Has any part of the site been classified as an "environmentally sensitive" area? If so, specify. Yes, Gilliam Creek is designated as a stream and the slopes at either end of the bridge are steep. i. Approximately how many people would reside or work in the completed project? None. j. Approximately how many people would the completed project displace? None. k. Proposed measures to avoid or reduce displacement impacts, if any: None. 1. Proposed measures to ensure the proposal is compatible with existing and projected land uses and plans, if any: The new bridge will be constructed to adequately carry projected traffic volumes. Page 11 ENVIRONMENTAL CHECI IST 9. Housing a. Approximately how many units would be provided, if any? Indicate whether high, middle, or low - income housing? None b. Approximately how many units, if any, would be eliminated? Indicate whether high, middle, or low - income housing. None c. Proposed measures to reduce or control housing impacts, if any: Not applicable 10. Aesthetics a. What is the tallest height of any proposed structure(s), not including antennas; what is the principal exterior building material(s) proposed? No buildings are planned. Retaining walls will be limited to minimum required. Overhead utilities will be relocated underground. b. What views in the immediate vicinity would be altered or obstructed? None. c. Proposed measures to reduce or control aesthetic impacts, if any: None. Page 12 ENVIRONMENTAL CH( 'LIST. 11. Light and Glare a. What type of light or glare will the proposal produce? What time of day would it mainly occur? The project will include standard street luminaires. b. Could light or glare from the finished project be a safety hazard or interfere with views? The proposed system is expected to improve public safety. c. What existing off -site sources of light or glare may affect your proposal? None. d. Proposed measures to reduce or control light and glare impacts, if any: None. 12. Recreation a. What designed and informal recreational opportunities are in the immediate vicinity? None. b. Would the proposed project displace any existing recreational uses? If so, describe. No. c. Proposed measures to reduce or control impacts on recreation, including recreation opportunities to be provided by the project or applicant, if any: None. Page 13 ENVIRONMENTAL CHEC GIST 13. Historic and Cultural Preservation a. Are there any places or objects listed on, or proposed for, national, state, or local preservation registers known to be on or next to the site? If so, generally describe. None known. b. Generally describe any landmarks or evidence of historic, archaeological, scientific, or cultural importance known to be on or next to the site. None known. c. Proposed measures to reduce or control impacts, if any: None. 14. Transportation a. Identify public streets and highways serving the site, and describe proposed access to the existing street system. Show on site plans, if any. The proposal is a public street. b. Is the site currently served by public transit? If not, what is the approximate distance to the nearest transit stop? No. c. How many parking spaces would the completed project have? How many would the project eliminate? The project does not require or change any parking. Page 14 ENVIRONMENTAL CHE( L d. Will the proposal require any new roads or streets, or improvements to existing roads or streets, not including driveways? If so, generally describe (indicate whether public or private). No. e. Will the project use (or occur in the immediate vicinity of) water, rail, or air transportation? If so, generally describe. No. f. How many vehicular trips per day would be generated by the completed project? If known, indicate when peak volumes would occur. This project is not expected to result in more vehicle traffic, ped traffic is expected to increase with the addition of sidewalks. g. Proposed measures to reduce or control transportation impacts, if any: None. 15. Public Services a. Would the project result in an increased need for public services (for example: fire protection, police protection, health care, schools, other)? If so, generally describe. No increase is expected. b. Proposed measures to reduce or control direct impacts on public services, if any. None. Page 15 ENVIRONMENTAL CHECIIST 16. Utilities a. Circle utilities currently available at the site: electricity, natural gas, water, refuse service, telephone, sanitary sewer, septic system, other. NA. b. Describe the utilities that are proposed for the project, the utility providing the service, and the general construction activities on the site or in the immediate vicinity which might be needed. No new utilities are proposed with the project, existing overhead utilities will be placed underground. C. SIGNATURE The above answers are true and complete to the best of my knowledge. I understand that the lead agency is relying on them to make its decision. Signature: Date Submitted: Page 16 ///, 9y ENVIRONMENTAL CHE ' LIST D. SUPPLEMENTAL SHEET FOR ALL PROJECT AND NON PROJECT PROPOSALS The objectives and the alternative means of reaching the objectives for a proposal will be helpful in reviewing the foregoing items of the Environmental Checklist. This information provides a general overall perspective of the proposed action in the context of the environmental information provided and the submitted plans, documents, supportive information, studies, etc. 1. What are the objectives of the proposal? Replace the existing, structurally deficient and functionaly indequate bridge. 2. What are the alternative means of accomplishing these objectives? The existing bridge could be repaired and widened to meet current standards. 3. Please compare the alternative means and indicate the preferred course of action: Due to the cost of renovating the existing bridge, it is more economical to replace it. 4. Does the proposal conflict with policies of the Tukwila Comprehensive Land Use Policy Plan? No 5. Proposed measures to avoid or reduce the conflict(s) are: None. Page 17 51ST AVENUE SOUTH BRIDGE REPLACEMENT 4J TUKWILA SITE 5. ,4th CF PRO.ECT SU 6+0103 BGINHIN Cr PRIXECT --\ STA. 1.1.47.87 VICINITY MAP Scar • mom AJD • .c5" t 40 . .SARGENT ENGINEERS INC. . CITY ( . 1 . CONSULTING CNGINCCRS 320 Int bay Drive. Suite 101. Olnopii. to VW: 011 001 Sb OZl 73 00 +t -° ?S 011 f Jald And JO 'd9 001 06 06 013 06 001 011 011 .0-,t1 .0-,t1 ..0-.5' /1.. 07 0l? 0B 06 001 OZ'611 73 00'L6+1' 'NS Z Ja/d f 911 %3 0005'+Z 'n7S 1 Jald ... pas 011 •7 And Jo •ig • • • • • • • xL —, • • • • • • • • 1 In lu — ,�-- - ri u 7 i L - - -- �J C7 — CI E c 4 m� I cc 1— u �. as ml W Zt`n W > a; �o KING COUNTY. WASHINGTON 'Y' INTERIOR PIER DEPARTMENT a C7 CONSULTING ENGINEERS 1ff lt� 04sw RMH •a• .01 Pla•••4- 'atft•S H IGHVVAY SR 10 MP 310 E I Cs1.-11 S 5 P/ 509 10 SP, 5!“ • • t. • •C• ••••.... • &ow) 4A.A.44.• P• •-•JA• I 4'4e,A; 12:1 22-5 **p!, • *V 25 1• 04, OS ▪ 1.1 •40,4 .• I " •• • ••• . 40 41 : • , • qv 4 2— • o . 44, 41, • • • , C7 • • s 394 404 "." . • • .; I: 44. • 57 94!■1.. or • • • •fr , • ' 4i ki-44-4, • rr. • At I" N SS • 42 • 41 111 ,67.0.0160T H • L.'.3 . d` •1..$•.r rl.f AVE., S. l4.A...Al... L94 -0102 51STAVE. S. BRIDGE REPLACEMENT i•.fiYK`/7 t� � \,tf S'A,•5 � s t •x ..�,}. .i. J }f "YF` rJ.; ,) .f .�:� 1 �4i,4 i. '5.:. ..1 +• ilk t 'Hr,'n3�t. r P7- 't��.: iti:�i .x= �J °.i.'�5�•.t 7S-F7:'�9 )i; - P... ^. .,../:• ,,.rCx'^.•/ qi�dkG '??j -Ss i.r`. r: )" .. ,!. . !: •..I .:4 r. t � •,T.: ..r ,• . mile j,..i,..i `e s�.';v u C n x :..wc.> Y� u.� �'.. 'e 1T,°,� iy . :..1•, ! ..i `. r.i � k. t$s, �. ,.,a) tNw ,IIw...{ {ir U.� �'� } .�...r.: ,.'i �: �i. ,..v ..� ..'_..',. .n. .. :'..:. ... ... " . ,t: :','•, :". _ hh 1 l .i� le 'f �'. �•t..a:p. J +w w4J J t_4 , ts: c�..v ..... .. . 5.. ���pgyJ�!?F . �. _ li•F_S'''�,i :.{:''L:1 "1,_u..ezi'`L1 <'..;i ..pIra..: ...�: {. �9.p.. ;Y'+..4,C)'„�iFi sh*'••Sft ;:r :�fj,.•::•�..:.t'�!G�Sytlrr v€�S "t�xi+. 111 ICI I1I 111 I1I 111 I1I I1I I1I ICI I1I 111 1 111 I1I X11 1 1 I1I ICI I1}I 111 I1I ICI I1I �1 ICI ICI ICI I1I ICI ICI I11 1 1 1.1 I1I ICI 111 111 I1I I1I 1 1 ICI 111 ICI 1 1 II I III, tu1.1 II I I I ' I I I I I I I' I I I I I I I I; 0 16 THS INCH 1 / 4 5 6 7 8 9 10 11 MADE IN G(RMANY 12 „kyftv.Ya, s.. ®FLEXIBLE RULER-302AWoERMANV- 6Z 8-L.Z. SZ V GL oZ 6l 81 Ll 91 +il al. 13 01 \13/4111111111111111 1� 111111111111111111 \111111111 \111111111 \n1111111�In1 1 1111111 111 1 11 1 1111111 1110111111111111111111 111111 iii 11 1 <2�• ".rr^_;...4,�9' °.'}•+','4.,,,Gji ,u . dir • " �''.i ' %,' ''w.r� ;C..�w o" N%h' '. JF a ..J. , ,.:;. � �_t,F`' '.... d f.v `i�`;_,, ... ,..,__. i ,.._... . _a:�_ _ a.3z' ,a�':4'�.7,+G`..';Y._.w. .. • .•ftyi� :>r..,f '¢ham. 'F'�,,. d _, _,. ,..�, .. t•' � ra. �k ;��;����'�,`��„�.�.�•"•��c;?N "� r 41e • IF THIS MICROFILMED DOCUMENT IS LESS CLEAR THAN THIS NOTICE, IT IS DUE TO`: ;:THE QUALITY OF THE ORIGINAL DOCUMENT � I 11 i " � 1 1 1 I ( 1 1 1 1 1I III I@ I1.s f l l V 2x4 wood posts at 6' —O" oc mo+{ provide steel posts at Contractors option - 2x?x14 ga wire or equivalent - embed ' 12'• below grade as shown Staple securely to posts • -Filter Fabric loop around.Glavel trench as shown. Staple securely to posts. .Joints in Filter Fabric shall be lapped ot, posts. . Varies: l4'6" -16'0 EXPECTED AREA OF DISTURBANCE - CONTRACTOR PROVIDE DRAWING SIGNED BY A LANDSCAF'E ARCHITECT OR BIOLOGIST ADDRESSING THE RESTORATION OF THE DISTURBED AREAS FOR CITY REVIEW PRIOR TO PERFORMING WORK. DRAWING SUBMITTED BY CONTRACTOR SHALL MEET THE MINIMUM REQUIREMENTS INDICATED ON THE "TYPICAL CREEK RESTORA TIOIJ.. DETAIL" AND THE "TYPICAL BANK PLANTING REQUIREMENTS ". -..-Restore north bank of creek adjacent • .to existing bridge .foundations :with existing bog formed concrete "rocks" or equivalent 3/4" washed gravel backfill typ Line streombed with it-6" quorry spalls to a min., depth. of 8 . • • Typical Creek Restoration Detail NO SCALE . . • • r. • Typical Bank Planting Requirements ZONE PLANT COMMON NAME 1 1 Shrub Vine Maple 1 2 Herb Oregon Grape 1 3 Salal 1 4 Hazelnut 2 5 HerbSword.Fern. 2 6 Salal; 2 7 Shrub Vine Maple. 2 , 8 Salmonberry 2 9 .Red elderberry 2 10 Hazelnut 2 11 Tree Red. alder 2 12 Western Red Cedar 3 13 Herb Lady fern 3 14 •Shrub Salmonberry 3 15 Indian Plum 3 16 Thimbleberry 3 17 Willow cuttings SCIENTIFIC NAME Acer circinatum Mahonia nervosa Gaultherla shallon Corylus cornuta' Polystichum munitum Gaultherla shallon Acer ct'rcinatu'In Rubus spectabi,Cls Sambucus racemosa Corylus'cornuta Alnus rubra Thu,Ja pllcata Athyrlum Fllix- Fem,lna Oemlarla cerasiformis Rubus parvlflorus SIZE,. • 4 -5 Gallon. 1 Gallon 1 Gallon 1 Gallon 1 Gallon • ' • .!15' . Ga1°lon •• Bare Root. - 3 Feet Bare Root - 3 Feet Bare root B Feet Ball &Burlap,- `7.Feet 1 Gallon:: 3 Feet' ' Bare Root - 4.Feet are Root :-'4. Feet. Cuttings PLANTING SPECIFICATION 15 - distribute evenly In 2' o.c. grid - stagger w/ . 2' o.c. grid - stagger w/ 2' o.c.-grid - stagger w/ 2' o.c, grid - stagger w/ 10 - distribute evenly In 5' o.c, grid - stagger w/ 5' o,c, grid - stagger w/ zone 1 #3 #2 #6 #5 zone 2 #9 #8 10 - distribute evenly in zone 2 10 - distribute evenly in zone 2 3 rows at 6' o.c, - .stagger w/ 014 3 rows at 6' o,c,.- .stagger w/ 013 1 row at 6' o,c, - alternate w/ #16 1 row at 6' o.c. - alternate w/ 015 Zone 1 occurs In the. high . slope areas.awayFrom the creek. • Zone 2 occurs in•the low slope areas..ad,Jacent to the creek bank area, Zone 3 occurs immediately .adjacent to the creek for a width of approximately 5 feet. . by.. date-. �n(�p pn /� �ny�(� 4•17. �, T 3 T , I c 11 S .� IIE P T . designed ©OI1Ve�JVL�TL Ql1V U 5 1 A VE. S. BRI D.GE REPL A CEMEN T /,•���� `;: +\ drawn ,. • r ;'. — ENGINEERING — STREETS— WATER — SEWER- PARKS— BUILDING- �(` �'ICLN.t.±' -j. checked ��., ::;.' .. ... prof eng .. .. ` �. file no i:'- pro, dlr PROPOSED BANK RESTORATION � PLAN � scale field bk no no date revisions date RECF N ED vw 1 8.1995 ,:a`e'�;F'', • ' '' : ' .,i'S Y' ea, .k'q • . .• 1 Y ;i^{ a� i6.'L'�fitf l �;c`'� r,`s�n £ag' .ro. : +4 r r.,: n,:lr'•i�`�?Jiy> Z G`�.�.t.;#a > P.•� 1, %i+.., 3> f I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I O III INS INCH 1 2_ 4 5 6 7 8 9 10 11 �"ale «•N. 1� FLEXIBLE RULER -302 IF THIS MICROFILMED DOCUMENT IS LESS . '• CLEAR THAN THIS NOTICE, IT IS DUE TO I: THE QUALITY OF THE ORIGINAL DOCUMENT[.... V€ 6Z eL LZ 9Z SZ +rL EZ LL LZ OZ 6L el ��I1 1ii�Ii Ittu l 111111n1nu101111nllnil11Iltllnn1Indnu1ludiullmllmllluduu1uu1 1 • N. • • . by.. date-. �n(�p pn /� �ny�(� 4•17. �, T 3 T , I c 11 S .� IIE P T . designed ©OI1Ve�JVL�TL Ql1V U 5 1 A VE. S. BRI D.GE REPL A CEMEN T /,•���� `;: +\ drawn ,. • r ;'. — ENGINEERING — STREETS— WATER — SEWER- PARKS— BUILDING- �(` �'ICLN.t.±' -j. checked ��., ::;.' .. ... prof eng .. .. ` �. file no i:'- pro, dlr PROPOSED BANK RESTORATION � PLAN � scale field bk no no date revisions date RECF N ED vw 1 8.1995 ,:a`e'�;F'', • ' '' : ' .,i'S Y' ea, .k'q • . .• 1 Y ;i^{ a� i6.'L'�fitf l �;c`'� r,`s�n £ag' .ro. : +4 r r.,: n,:lr'•i�`�?Jiy> Z G`�.�.t.;#a > P.•� 1, %i+.., 3> f I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I O III INS INCH 1 2_ 4 5 6 7 8 9 10 11 �"ale «•N. 1� FLEXIBLE RULER -302 IF THIS MICROFILMED DOCUMENT IS LESS . '• CLEAR THAN THIS NOTICE, IT IS DUE TO I: THE QUALITY OF THE ORIGINAL DOCUMENT[.... V€ 6Z eL LZ 9Z SZ +rL EZ LL LZ OZ 6L el ��I1 1ii�Ii Ittu l 111111n1nu101111nllnil11Iltllnn1Indnu1ludiullmllmllluduu1uu1 1