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SEPA EPIC-04-89 - PRIMARK CORPORATION - SYLVAN GLEN APARTMENT, RECREATION AND DAYCARE CENTERS
SYLVAN GLEN CONSTRUCTION OF APARTMENT COMPLEX, RECREATION & DAYCARE CENTER 18059 57T" AVE S. EPIC 4 -89 PRO Z-E c:r CAN.0 erZ, 40 City of Tukwila 6200 Southcenter Boulevard Tukwila Washington 98188 (206) 433 -1800 Gary L. VanDusen, Mayor November 6, 1989 Hong Tan Primark 1200 South 192nd St. Suite 102 Seattle, WA 98148 RE: Final EIS Scoping for Sylvan Glen (EPIC- 4 -89). Dear Mr. Tan: I reviewed your suggested modifications to the EIS Scope and conclude that no substantive changes to the draft scope are warranted. This decision is primarily based on the need to clearly and appropriately demonstrate that the proposed buildings can be built as shown and where shown without further analysis or development revisions. The final EIS scope is shown in Attachment A. It reflects the level of analysis normally required to clearly and appropriately demonstrate the specific construction's feasibility when we can measure the impacts of the proposal. I have also attached the Geotechnical and Utilities analysis of the Valley View Estates EIS to illustrate the depth and breadth of analysis expected (Attachment B). Vernon Umetsu will continue to work with you as the City's project planner and is available to answer any general questions. He will be out of the office until November 20th, and general questions may be referred to me during the interim. Specific technical questions should be resolved directly with the appropriate departments. This final EIS scope may be appealed to the Tukwila City Council within ten days after the date of this letter by submitting a written appeal to the City Clerk. After finalizing the E.I.S. scope, a contract between consultant and City can be negotiated. Draft E.I.S. contracts are generally negotiated on a fixed cost basis. Final E.I.S. costs will be negotiated later once comments have been received. The contract will be executed and work authorized by the City upon receipt of a check for the total estimated amount. Since L. Rick Bee er SEPA Responsible Official ATTACHMENTS cc: Ray Flink c/o Linda Youngs and Betty Drumheller Fraser TTACffiMENT Sylvan Glen Draft Environmental Impact Statement Contents /Consultant Scope of Work The contents of the following sections shall clearly evaluate existing conditions, project impacts, mitigating measures and unavoidable adverse impacts in light of the City's comments. PART I: INTRODUCTION Title Page Preface Fact Sheet Table of Contents List of Tables List of Figures Summary of Impacts and Mitigating Measures Description of Proposed Action Project description shall include, but not be limited to materials required for Board of Architectural Review submittal: A. ALTERNATIVES TO BE EVALUATED IN THE D.E.I.S. 1. The Proposed Action Without realignment of South 178th Street. 2. Project with South 178th Street realignment Realignment as determined by city engineer; number of units may be reduced or remain the same as proposal. 3. Proposed action with two story units grouped along public street frontages. 4. Office rather than multi - family use. 5. No action. A description of all alternatives shall be provided with the same level of detail as the proposed action including, but not limited to: plan view, elevations, cross - sections, grade and fill plan, and typical structural engineering (to be coordinated with engineering safety factor calculations in Earth). A preliminary site plan of alternatives shall be approved by the SEPA Official prior to detailed design. • • PART II: ELEMENTS OF THE NATURAL ENVIRONMENT A. EARTH Discussion based on the geotechnical report by Golder Associates as reviewed by Dames and Moore. This discussion shall include, but not be limited to the following: Existing Conditions 1. Ground surface profile(s), indicating original and proposed grades. Such profile(s) shall be estimated beyond property lines in the vicinity of South 178th Street where necessary to evaluate conditions which may affect the site or adjacent sites. A site topographic survey by a licensed surveyor at a minimum 30 foot scale, shall show existing contour lines with shot locations and elevations noted, surrounding properties, existing structures, street right -of -way and the proposed development shall be provided. 2. Description of subsurface conditions including geology, soil /bedrock stratigraphy, shallow and deep groundwater conditions, and engineering characteristics. Evaluation of the slope stability conditions of the site requires information on the geometry of any past slide, deep soil conditions, and groundwater elevations. Exploration logs and laboratory test results shall be provided. 3. History of site conditions will also be documented based on review of: a. Washington State Department of Transportation (WSDOT) Construction Records for I -5 and South 178th Street b. City of Tukwila Public Works Engineering Department information c. Sensitive areas Map Folio for King County, Washington, December 1987 d. Aerial photographs Impacts 1. Description of proposed structure and utilities including the engineering safety factors. 2. Approximate floor grades /excavation levels of proposal. 3. The present stability of the site, the stability during construction, and the stability of site areas after the proposed development is completed will be provided, including a statement of the relative risks at each stage, the slide potential relating to abutting properties, and stability under seismic conditions will be documented. Existing and finished grades, grading and earthwork, includ- ing compaction and fill material requirements, use of site soils as fill or backfill, imported fill /backfill specifications, height and inclination of slopes. 5. Assess drainage /erosion hazards on and off site, during and after construction of the proposed building foundation and grading. Mitigating Measures Specific measures for: 1. Short term construction period. 2. Long term recommended construction and structural design. B. WATER Existing Conditions 1. Surface water areas in vicinity to be inventoried. 2. Subsurface water covered under "Earth ". Impacts 1. To be addressed in Earth. The geotechnical analysis will evaluate impacts and mitigating measures for site drainage. Mitigating Measures Alternative measures to mitigate drainage impacts to be explored include on -site retention and upgrading the pump station at South 178th Street /Southcenter Parkway. B. ]NOISE Existing Conditions /Impacts /Mitigating Measures Conduct a noise study to establish existing noise conditions and . document the effect of freeway noise impacts upon the proposed development (i.e. living, sleeping, and recreation areas). Effect of site plan, proposed structures and adjoining topography on projected noise levels shall be documented. The JGL noise study provides a useful prototype document for impact analysis and mitigating measures. PART III: ELEMENTS OF THE BUILT ENVIRONMENT A. LAND USE Existing Conditions Documentation should encompass the site and surrounding area from South 178th /South 180th to City limits, and from I -5 to 57th Street. Impacts Land use impacts to be evaluated for to each alternative. 1. Discuss whether the proposed change will significantly affect the viability of Comprehensive Plan land use designa- tions for adjacent properties. 2. Consistency of each alternative action and impacts with Comprehensive Plan land use policies and map, and environmental (steep slope) policies. 3. Discuss cumulative impacts of more intensive uses in terms of capability of area utilities (water, sewer, transportation network) to support more intensive uses. 4. Please note that consistency with adopted plan elements is required for Comprehensive Plan amendments, including, but not be limited to South 178th /South 188th Street improve- ments. The Public Works Department should be contacted for determination of consistency with road and utility plans. Mitigating Measures Mitigating measures to be identified by alternative. B. AESTHETICS Existing Conditions Views of project site must be documented from the four sites indicated on the attached map. Photographs may be required to clearly show the existing site, and as a base on which project alternatives will be shown. Impacts The proposed alternatives must be graphically superimposed onto existing conditions. Mitigating Measures Summarize mitigating characteristics of project design etc. C. TRANSPORTATION Existing Conditions Document existing LOS for South 178th /South 180th, Southcenter Parkway and South 180th /Military Road intersections, and Military Road /South 188th, trips, accident rates, and pedestrian facili- ties. Specific transportation system evaluations shall include: 1. Trip generation and distribution of ADT and PM peak hour traffic, and the following LOS intersection analyses: Southcenter Parkway /South 180th Street. LOS analysis shall be per the latest ITE capacity manual. 2. Vehicle and pedestrian safety analysis to include pedestrian walking routes, school routes, and school and Metro bus accessibility. 3. South 178th Street is not available as year -round street due to 21% grades. Analyze alternative alignments for South 178th Street in consultation with the Public Works Department. 4. Identify emergency access for fire, police, and ambulance, existing and as proposed by mutual aid pact for fire and emergency medical. 5. Identify King County and WSDOT requirements for new I -5 freeway ramps at its intersection with South 178th Street. Impacts 1. Trip generation, travel pattern, and road capacity analysis per direction of the City Engineer to address impacts on above existing conditions. 2. Consistency of development with Six Year Transportation Improvement Plan. Consult City Engineer for demonstrating proposed project has made provision for the South 188th /South 178th Street improvements. 3. Consistency of internal circulation pattern with Fire Department and Public Works standards. Mitigating Measures 1. Evaluate the need for specific road improvements to mitigate immediate development impacts, the need for a no protest agreement for the formation of an R.I.D. to provide the project's fair share in resolving cumulative transportation impacts, and pedestrian improvements. 2. Identify mitigation and funding sources (LID participation, etc.) for safety and capacity impacts including the vehicle, pedestrian, and emergency access. D. UTILITIES Existing Conditions 1. Describe existing facilities on and adjacent to site: access points, and system capacity. Complete a sewer, water, storm drainage capacity analysis. Reference impacts of cumulative land use changes in Land Use. Please note that storm drainage system capacity is especially limited in this area. 2. Certification of water availability from W.D. No. 75 shall be required. Tukwila fire pressure and flow standards shall be satisfied and documented. 3. An engineering analysis of sewer availability at the site and sewer system capacity to satisfy project demand shall be conducted. Horton Dennis (Marty Penhallgram) has recently completed an evaluation of sewer capacity in the area. Impacts Identify impacts of failed systems. Evaluate the need to provide for the impacts of failed sewer and water systems (i.e. by thrust blocks, double walled pipes, and regular maintenance). Mitigating Measures Identify specific improvements to system capacity to satisfy the immediate needs of the project, and any "no protest" L.I.D. agreements which should be executed to ensure the project pays its fair share of cumulative system improvement needs. APPENDIX Distribution List and Mailing Labels • CHIIeW T��.. 'AO GeoEngineers Incorporated (206) 881-7900 P.O. Box 6325 2020 124th Ave. N.E. Bellevue. WA 98008 April 25, 1985 Stepan and Associates, Inc. 930 South 336th Street, Suite A Federal Way, Washington 98003 Attention: Mr. Glen McKinney Gentlemen: Consulting Geotechnical Engineers and Geologists We are pleased to submit two copies of our "Report, Geotechnical and Hydrological Studies, Proposed Valley View Estates, Slade Way and 53rd Avenue South, Tukwila, Washington ". This report was developed in two phases. The scope of services for the first phase was outlined in our proposal dated August 9, 1983, and the Phase 1 report was presented on February 17, 1984. This report replaces and supplements our Phase I report. The Phase II services consist of collecting additional data and expanding some of our previous analyses to respond to comments raised during hearings on the Draft Environmental Impact Statement. These services were performed under a confirming agreement dated July 16, 1984 and were expanded by verbal authorization from Mr. Tom Russell, project manager for Puget Western, on several occasions. We have enjoyed working with you on this project and are looking forward to continuing our relationship during the instrumentation installation and monitoring, and construction phases of the project. Should you have any questions or need additional information, please call. GMD:JKT:da File No. 523 -02 cc: Puget Western (8) Attn: Mr. Tom Russell Yours very truly, ineers, .nc. Ja'1C..K. Tuttle ,r..incipa1 T A B L E O F C O N T E N T S INTRODUCTION SCOPE REVIEW OF SITE HISTORY SITE CONDITIONS SUBSURFACE CONDITIONS GEOHYDROLOGICAL AND SURFACE WATER CONDITIONS STABILITY INTRODUCTION DEEP - SEATED SLIDING SHALLOW- SEATED SLIDING Page No. 1 2 4 7 9 10 12 12 12 14 CONCLUSIONS AND RECOMMENDATIONS 16 GENERAL 16 EVALUATION OF I -5 DRAIN SYSTEM 18 SITE DEVELOPMENT 21 STRUCTURAL FILLS AND PAVING 24 RETAINING STRUCTURES 25 FOUNDATION DESIGN 27 INSTRUMENTATION AND MONITORING 28 USE OF THIS REPORT 31 List of Figures Figure No. SITE PLAN 1 HORIZONTAL DRAIN AND WELL SYSTEM 2 EXISTING ON SITE HORIZONTAL DRAIN LAYOUT 3 CROSS SECTION A -A1 4 SCHEMATIC OF PROPOSED INTERCEPTOR DITCH 5 i GeoEngineers Incorporated APPENDIX A Page No. FIELD EXPLORATIONS AND LABORATORY TESTING A -1 FIELD EXPLORATIONS A -1 LABORATORY TESTING A -1 Appendix A Figures UNIFIED SOIL CLASSIFICATION SYSTEM AND KEY TO SAMPLE DATA LOGS OF EXPLORATION APPENDIX B Figure No. A -1 A -2 T ru A-19 Page No. INSTRUMENTATION AND MONITORING B -1 PIEZOMETRIC LEVELS B -1 INCLINOMETER DATA B -1 TABLE B -1 B -2 TABLE B -2 B -3 TABLE B -3 B -4 TABLE B -4 B -5 APPENDIX C Page No. SLOPE STABILITY ANALYSES C -1 INTRODUCTION C -1 Methodology C -1 Assumptions C -1 Selection Parameters C -3 Results C -3 Additional Analyses C -3 Dynamic Analysis C -4 SHALLOW SLIDING C -4 Appendix C Figures Figure No. CROSS SECTION FOR STABILITY ANALYSIS C -1 & C -2 ii GeoEngineers Incorporated REPORT GEOTECHNICAL AND HYDROLOGICAL STUDIES PROPOSED VALLEY VIEW ESTATES SLADE WAY AND 53RD AVENUE SOUTH TUKWILA, WASHINGTON FOR DR. H. M. ALLENEACH INTRODUCTION This report presents the results of our geotechnical and hydrological studies of the site proposed for construction of Valley View Estates. The report replaces and supplements our report dated February 17, 1984. Revisions to the report include additional water level data obtained since issuance of the initial report. We also address, in expanded detail, specific issues raised during review of the Draft Environmental Impact Statement. The site is located adjacent to the west right - of-way for Interstate Highway No. 5 and is bounded on the south by Slade Way and on the west by Slade Way and 53rd Avenue South, as shown on the Site Plan, Figure 1. The proposed development includes construction of 18 six -unit residential structures together with associated roadways, parking areas and utilities. The units will be stepped into the hillside, requiring varying depths of cut. Some cutting and filling will also be required to construct the roadways and parking areas as well as to establish reasonable grades around the various buildings. Wood frame construction which will result in relatively light foundation loads is planned. The proposed residential property is located within a very large, prehistoric, landslide zone. Also, a substantial portion of the property was involved in the landslide which occurred in 1960 as the result of excavation of borrow material which was used for fill in the Andover Industrial Park. The stability of this and adjacent properties on the southwest portion of the interchange of the freeway with State Route 405 has been improved by the remedial drainage measures which were installed by the Washington State Department of Transportation (WSDOT) during construction of Interstate. Highway No. 5. No evidence of recent deep - seated movement was noted during GeoEngineers Incorporated • • our site examinations. The WSDOT drainage facilities include systems of horizontal drains and vertical wells, a number of which exist immediately east of this property. SCOPE The scope of services for these studies was developed. and executed in two phases. Phase I was developed following a meeting on August 2, 1983 of the various parties involved in assembling information for the Environmental Impact Statement for this project. Phase I reflected our assessment of the extent of study which we considered to be appropriate for-this project, based on studies made for the 1960 -61 landslide by members of our staff while employed with Dames & Moore and a review of existing surficial site conditions by our firm in 1982. Our proposal for Phase I was submitted in a letter dated August 9, 1983. We received authorization to proceed in September 1983. The purpose of the Phase I services was twofold: 1) to develop pertinent information on soil and ground water conditions for inclusion in the Environ- mental Impact Statement, and 2) to develop further design criteria, as appropriate, for the geotechnical aspects of the project. The Phase I scope of services includes: 1. Exploring subsurface soil and ground water conditions by drilling a series of test borings from which representative soil samples were obtained and in which piezometers were installed to monitor ground water conditions at appropriate levels. 2. Evaluating pertinent physical and engineering characteristics of the soils from the results of laboratory tests. 3. Reviewing information available from the Washington State Department of Transportation on the subsurface drainage system which was installed in the site area during construction of Interstate Highway 5. 4. Defining, to the extent possible, past landslide history of the immediate area. 5. Evaluating the overall stability of the project site for present geotechnical and hydrological conditions. 2 GeoEngineers Incorporated 6. Evaluating pertinent design criteria for the geotechnical elements of the project, including stability of cut and fill slopes, design criteria for shallow foundations, retaining structure design criteria, earthwork procedures, and site drainage requirements. In addition, our scope of services for Phase I was expanded to include the installation of a slope indicator casing and obtaining an initial set of readings at Boring F. This installation has been made in an area of past sliding, but lies above the area of planned development so that information from subsequent readings will provide a means of monitoring any movements of the hillside in the area between Slade Way and the planned residential development. The Phase II scope of services was developed following public hearings on the Draft EIS. The scope of services was developed with Mr. Tom Russell, project manager for Puget Western, Inc. and was authorized verbally. The purpose of the Phase II services is to gather additional information on the geohydrologic regime in the hillside and to respond to comments on the Draft EIS. The Phase II scope of services includes: 1. Obtaining an additional set of readings of the piezometers and the slope inclinometer. 2. Flushing out several piezometers installed by others adjacent to the site during investigations for the construction of 1 -5. 3. Obtaining additional information on the Washington State Department of Transportation well system including sounding the depth and recording the water levels in the wells. 4. Reviewing the Phase I assessment of the geohydrologic regime on the hillside with regard to the additional water level data. 5. Conducting additional static stability analyses to evaluate the stability of the hillside relative to pre- and post -drain installation and to develop criteria for identifying the extent to which water levels in the hillside can safely rise before remedial drainage measures would need to be initiated. 6. Conducting dynamic stability analyses to evaluate the hillside stability under earthquake conditions. GeoEngineers Incorporated 7. Expanding our Phase I recommendations for monitoring and instrumen- tation of site stability prior to, during, and following construction. REVIEW OF SITE HISTORY The review of the site history included examining files of the Washington State Department of Transportation in Olympia and various soils reports pertaining to the site specifically and to the adjacent slope stabilization measures accomplished during 1 -5 construction. The soils reports that were reviewed include: - "Report of Stability Investigation, Borrow Area Slide, 54th Avenue South and South 162nd Street; Tukwila, Washington ", by Dames & Moore, December 1, 1960. - "Report of Soils Investigation, Earthslide, South 162nd Street Near 53rd Avenue South, Tukwila, Washington ", by Dames & Moore, June 27, 1961. - "Report on Foundation Investigation, Existing Slide Area, Tukwila Interchange, PSH -1 (SR5) ", by Shannon & Wilson, June 12, 1964. - "Summary Report, Slope Stability Investigation, Tukwila Interchange (SR5) ", by Shannon & Wilson, April 14, 1966. - "Summary Report, Soil Conditions and Earth Movements., Vicinity of the Tukwila Interchange ", by Shannon & Wilson, June 21, 1968. "Geotechnical Design Consultation, Proposed Residential Development, Slade Way and 53rd Avenue South, Tukwila, Washington ", by GeoEngi- neers, May 3, 1982. The listed reports document a large earthslide that occurred at the site in 1960 as material was being excavated from a borrow area immediately downslope of the site. The extent of the slide is well documented in the 1960 and 1961 reports and is shown in Figure 2. The slide covered the southern two- thirds of the site as well as extending another 200 feet upslope from the western boundary of the site. Measurements during October 1960 indicated that the slide area was moving an average of 0.5 feet per day. Movements continued at a diminished rate in 1961. Slope indicator measurements taken in conjunction with the Dames & Moore studies indicated that movements were occurring in a shear zone 25 GeoEngineers Incorporated to 40 feet below the ground surface through the central portion of the slide. In addition, the shear zone was indicated to consist of clayey soil underlain by a layer of waterbearing sand. The 1960/61 slide movement had resulted from the combined effect of excavation and the substantial artesian pressures existing in the waterbearing sand layer. The remedial measures considered were based on reducing the hydrostatic pressure within the waterbearing sand layer which appeared to immediately underlie the failure surface. Deep wells as well as horizontal drains and drainage trenches were considered. A series of horizontal drains was installed in the summer of 1961, together with some regrading of the borrow pit area. A plan from the Shannon & Wilson 1964 report showing the locations of the horizontal drains is presented in Figure 3. Altogether, 20 6- inch - diameter slotted pipe drains with lengths from 100 to 150 feet were installed. Eight of the drains were located along the toe of the roadway fill in the southwest corner of the site, while the remainder were located in the south - central portion of the site. The flow from the drains does not appear to be piped and is probably responsible for some of the existing wet areas at the site. The 1966 and 1968 reports are related to the overall stability of the hillside, both to the north and below this site, as it related to con- struction of the.I- 5/SR405 interchange and related roadways. At that time there had been considerable landslide activity not only at the project site but north and northwest along the hillside. Ten to twelve landslides of various dimensions were observed in these areas. The 1968 report shows several recent slide scarps at the project site. With one exception, all of these were less than 200 feet long and were aligned along the contour; however, one was approximately 700 feet long and was aligned approximately at 45 degrees to the contours in the northern third of the site. This scarp appeared to be the northern boundary of a large slide, possibly the 1960 -61 slide. The proposed remedial measures consisted of an extensive subsurface drainage system of vertical wells tied into horizontal drains and cylinder pile wall retaining structures as shown in Figure 2. In addition, an inter- ceptor drain, shown as the D -3 drain on Figures 2 and 3, was installed. 5 GeoEngineers Incorporated These remedial measures were initiated by the Washington State Department of Transportation and were subsequently monitored and reported on by Shannon & Wilson. The WSDOT drain system consists of a series of 5- foot - diameter wells tied into horizontal drains originating at the retaining wall along Klickitat Drive, as shown in Figure 2. The wells are located just east of the site. In addition to the large diameter wells, a number of small diameter vertical drains were installed in between the large wells as shown in Figure 2. Based on information in the Shannon & Wilson reports, the horizontal drains consist of 1 -1/2- inch - diameter unperforated plastic pipe with 10 -foot- long stainless steel well point tips. that every fifth drain have a section of stainless steel We have not located any records that verify whether In addition, it was recommended screen at mid- length. or not this was done. Information, including elevations, grades and lengths of the WSDOT horizontal drain and vertical well system, is presented in Table B -4 in Appendix B. Based on inspection of the wells, it appears that the original pumps are still in place in approximately 70 percent of the wells. The pumps and outlet pipes have been removed in the other wells. The condition of the in -place pumps is not known. Inspection of the outlets of the horizontal drain system revealed 42 outlets through the cylinder pile retaining wall along Klickitat Drive (see Figure 2). The length and orientation of any drains in these outlets other than those that lead to the wells is unknown. There may be short horizontal drains to drain immediately behind the wall or replacement drains to the wells. The extra outlets may also be weepholes to drain the zone behind the wall. Approximately half of the 42 drain outlets, primarily to the north, were dry at the time of our most recent visit (April 12, 1985). Flow through the other weepholes varied from a drip to about one gallon per minute. There was also significant flow between the wall panels in two places. At one location, the flow between the panels was estimated to be 4 to 6 gallons per minute. The 1968 Shannon & Wilson report also identifies a system of original test drains that were installed by WSDOT just east of the eastern property line and south of the horizontal drain /vertical well system (see Figure 2). 6 GeoEngineers Incorporated • • Our examination of the portions of this drain system still in evidence indicates that they are still at least partially functional. These drains consist of 1 -1/2- inch - diameter PVC pipe. The outlets are connected to buried manifolds, three of which discharge into a drainage gully. The fourth manifold was unable to be located. Approximately 60 percent of the drains were located, of which approximately 20 percent appear to be damaged and in need of repair. Local sloughing and erosion has occurred at the drain outlets in several places. Flows from the three manifold outlets ranged from approximately 0.25 to 3 gallons per minute. The 1966 Shannon & Wilson report summarizes potential failure modes for the landsliding on the hillside and, like the 1960 and 1961 studies by Dames & Moore, concludes that the mode of failure at the project site is due to the presence of a clayey silt underlain by sands with artesian pressures. The report includes classification and average strength values for the important materials in the hillside. These data were used in our studies. The Shannon & Wilson report concludes that the I -5 project area slopes (including the area in which the drains and wells are installed) are stable for the static conditions then (1968) existing. They also concluded that the soil materials in the slopes "are unlikely to be significantly affected by seismic activity ". Some evidence of near - surface movement, mostly in the form of shallow creep and flow slides, was noted in our examination of the site prior to preparing our consultation report of May 3, 1982. A recent scarp was observed a short distance east of Slade Way. The scarp is about 200 feet long and varies from about 12 to 20 inches in height. The downslope extent of the slide appears to be limited to the upper portion of the property in which no construction is planned. The slide was estimated to have occurred in 1981 or earlier, based on the extent to which vegetation had reestablished itself along the scarp. SITE CONDITIONS A plan of the site is shown in Figure 1. The site covers approximately 7 acres and is non - uniformly shaped, being bounded on the south and west 7 GeoEngineers Incorporated • • by Slade Way and on the east by the Interstate Highway No. 5 right -of -way. A sanitary sewer runs along contour through the eastern portion of the site. There is also evidence of the D -3 drain, as shown on Figure 2. The site slopes moderately to the east and northeast with isolated areas becoming moderately steep. A large drainage swale transects the southern portion of the site, resulting in the sewer alignment curving to the west around this swale before swinging to the northeast. There are three benches on the site that appear to be manmade. The presence of the benches may be indicative of remedial grading following previous slide activity. The lowest bench appears to have been constructed during the installation of the sanitary sewer line and essentially follows the sewer alignment to a point where the sewer line crosses the property line at the center of the eastern property line. The ground surface downslope from the sewer bench in the southeast corner of the site is moderately steep. A second bench starts at the southern property line slightly upslope from the sewer line bench and is oriented approximately parallel to the sewer line bench for approximately one -third the length of the site at which point it disappears. The third bench is located in the center of the site and may have been constructed during installation of an old surface drain in this area. Vegetation consists of areas of very dense berry vines, some exceeding 10 feet in height, fairly dense alder groves, scattered evergreen trees, particularly on the western portion of the site, and occasional horsetails, which are indicative of wet ground. Most of the alder trees located on the middle to eastern portion of the site appear to be fairly young, indicating that the site was likely stripped of vegetation following the slide in 1960 -61. Wet surface- conditions were observed over much of the site during our field explorations in October 1983. Some of these appear as seeps or springs, possibly originating from the horizontal drains installed in 1961 as shown on Figure 3. A corrugated metal pipe stormwater drain is located at the intersection of Slade Way and South 160th Street and is reported to parallel 53rd South for a short distance before turning east and tying into the D -3 drain. 8 GeoEngineers Incorporated The drain was leaking several gallons per minute at the time of our explor- ations. Flow from this drain was apparently being collected by the upper portion of the D -3 drain. SUBSURFACE CONDITIONS Subsurface conditions were explored at the site by drilling 8 borings using a truck- mounted, hollow -stem auger drill rig. The borings were drilled during October 13 to October 21, 1983. Because of wet conditions at the site and relatively steep slopes, a dozer was required to assist the drill rig in moving around the site. An engineer from our staff established the boring locations, maintained logs of the explorations, . and obtained relatively undisturbed samples for observation and laboratory testing. The boring locations, as subsequently surveyed by Stepan & Associates, Inc., are shown on Figure 1. Details of the field explorations, along with the boring logs edited to reflect laboratory examination and testing, are presented in Appendix A. Piezometers were installed in all borings except Boring F where an inclinometer casing which will permit future moni- toring of slope movements was installed. Both deep and shallow piezometers were installed in Boring J. Details of the piezometer and inclinometer instrumentation are presented in Appendix B. Subsurface conditions at the site were interpreted from borings in the 1960 and 1961 investigations and from the current drilling program. Three major units were identified at the site as follows: UNIT A: Fill and /or slope debris, probably native to the site and consisting of loose to medium dense silty fine to medium sands. Thickness varies between 5 and 10 feet. UNIT B: Gray silt interbedded with fine to medium sand. The gray silt varies in consistency between medium stiff to very stiff, generally becoming stiffer with depth. The silt has some zones which contain a trace to some clay. Slickensides are present throughout the unit as well as randomly oriented contacts between different gradations of materials. The sand layers appear to vary from 1/8 of an inch to one to two feet in thickness and are generally saturated. 9 GeoEngineers Incorporated UNIT C: Gray sandy silty gravel and gray gravelly sand with some silt. Consistency varies from dense to very dense and unit is generally saturated. Unit B generally grades into Unit C and is separated by a layer of gray fine to medium silty sand in some of the borings. The three units vary significantly both in depth and elevation across the site. As shown in a typical cross section in Figure 4, the units tend to follow the existing topography and slope down to the east. The thickness of the gray silt (Unit B) is less toward the south (25 feet in Boring C) and increases to the north (89 feet in Boring K). The dip of the surface of Unit C is to the northeast and may represent an erosional feature that occurred before deposition of Unit B. GEOHYDROLOGICAL AND SURFACE WATER CONDITIONS Two separate and independent hydrologic regimes exist at the site. The upper regime, existing within Units A and B, is influenced by surface water runoff, seepage from upslope, and direct precipitation. Seepage volumes are small due to the relatively low permeability of these soils. Water pressures in this regime are likely to be hydrostatic. In contrast, the lower regime existing within Unit C is influenced primarily by subsurface ground water flow. The source of water is not known; however, it is likely that it is upslope and to the west or southwest of the site. Water pressures in this regime were artesian at the time of the 1960 -61 slide. The permeability of the soil in the lower regime (Unit C) is significantly higher than the soils in the upper regime and seepage volumes would be expected to be cor- respondingly higher. The original water table at the site has been modified on three occasions in the past 25 years. The first modification occurred after the 1960 -61 slide when several on -site horizontal drains were installed in 1961 on the slope (see Figure 3). These were installed to alleviate the artesian pressures in Unit C and arrest the hillside movements. The second modification of the water table at the site occurred in 1966 when the Washington State Department of Transportation installed a 10 GeoEngineers Incorporated series of large- diameter wells (see Figure 2). These wells were then pumped during construction of a cylinder pile wall along Klickitat Drive to the east of the project site. The third and most recent modification of the ground water regime occurred near the end of construction of the cylinder pile wall when horizontal drains were drilled to intercept the vertical wells and the pumps in the wells were subsequently switched off. Water levels in the two ground water regimes were measured using the piezometers installed in our borings in October 1983, three of the piezometers installed by Shannon & Wilson in 1966 which we were able to locate, and the WSDOT vertical wells. Our piezometers are installed in Unit C, the lower ground water regime, with the exception of the second piezometer in Boring J which was installed in Unit B, the upper ground water regime. The piezometer levels in our borings were originally measured on November 18, 1983 and subsequently measured on three occasions between November 30, 1984 and March 12, 1985. These data are presented in Table B -1 in Appendix B. Several readings of the Shannon & Wilson piezometers and the WSDOT wells were also taken during this period. These data are presented in Tables B -2 and B -3 in Appendix B. The Shannon & Wilson piezometers were flushed in March 1985. The piezometric data collected from November 1984 to March 1985 indicate relatively stable water levels in the lower ground water regime (Unit C) at the site. Water level depths range from 29 to 77 feet below the ground surface at the site and 26 to 55 feet as measured in the Shannon & Wilson piezometers east of the site. The water level data from the WSDOT wells is less consistent and it appears that several wells or horizontal drains are plugged. This is discussed further in the section on "Evaluation of 1 -5 Drain System ". In the upper ground water regime (Units A and B), the water levels are expected to be variable, ranging from,the ground surface to depths of ten or more feet, depending largely on local topography, seasonal rainfall, and other factors. In Piezometer J, the water depth has been stable over the last six months at a depth of 9 feet. 11 GeoEngineers Incorporated STABILITY INTRODUCTION The purpose of the stability analyses is to assess the risk of instability of the hillside. The risk of sliding is related to existing conditions and to the effects of changing water levels in the hillside, as well as to earthquake activity. The analytical procedure consists of evaluating the gravitational force driving the soil downslope and the force of the soil (strength) resisting the sliding. The procedure also takes into account the effects that ground water conditions have on the resisting force. In general, the higher the water levels in the slope the lower the soil strength or resisting force. The risk of slide movement is expressed as a factor of safety which is defined as the ratio of the resisting force divided by the driving force. If the resisting force equals the driving force, the factor of safety is 1 and the risk of sliding is very high, whereas if the resisting force is greater than the driving force, the factor of safety is greater than 1 and the risk of sliding decreases as the factor of safety increases. Generally, slopes having a factor of safety greater than 1.5 are considered to have an acceptably low risk of sliding and are considered to be stable. Stability analyses were conducted to analyze both deep- seated and shallow- seated sliding. Details of the analyses including figures showing the failure surfaces analyzed are presented in Appendix C. A brief description and summary of the results of the analyses is presented below. DEEP- SEATED SLIDING The stability of the hillside was evaluated by considering the different topographic and ground water conditions which existed during the 1960 -61 slide and which exist in March 1985. The alignment of the section judged to be most critical of those analyzed is shown on Figure 1. The first set of analyses was conducted by assuming topographic and water level conditions recorded in 1960 and 1961 and back calculating the soil strength parameters required to yield a factor of safety of 1.0. 12 GeoEngineers Incorporated • • The soil strength parameters so determined are in good agreement and fall within the range of values reported by Dames & Moore and Shannon & Wilson and used in their analyses. The key parameter is the friction angle in the failure zone. The actual values used are as follows: Soil Along " Soil Above Failure Zone Failure Zone 0 c 0 c GeoEngineers, Inc. Shannon & Wilson, Inc. Dames & Moore D = friction angle in degrees. C = cohesion in psf. 15 0 25 0 14 0 -- 14 600 22° 350 700 0 The parameters determined in our studies were then used to analyze the slope stability for the March 1985 topographic and water level conditions inasmuch as we judge them to be a reasonable median value of the three sets of parameters reported. The results of these analyses indicate that the factor of safety of the hillside for current conditions is in the range of 1.5 to 1.6 for the sections analyzed. The increase in factor of safety is, in our opinion, primarily due to the decrease in water levels caused by the WSDOT drain system, and represents an acceptable factor of safety in relation to the planned project. The impact of building loads on overall slope stability was also evaluated and found to have a negligible influence on the factor of safety. The possibility of a decrease in the factor of safety with a rise in the water level resulting from deterioration of the drainage system was also evaluated. The results of this evaluation (see Appendix C) indicate that the risk of sliding would become very high, i.e. FS = 1.0, if the water table were to rise an average of 20 feet above the March 1985 levels in the lower artesian aquifer. (See Tables B -1, B -2 and B -3.) The stability of the hillside was also evaluated for earthquake condi- tions. For this condition, the ground shaking during the earthquake increases the driving force. The seismic increment was approximated in the analysis by an equivalent static force proportional to a nominal horizontal ground acceleration (pseudo static method). For the project area, a horizontal 13 GeoEngineers Incorporated • ground acceleration of 0.15g, where g is the acceleration due to gravity, was assumed. This value is typically used for seismic design in the Seattle area. It should be noted that the factor of safety calculated using the pseudo static method has a different connotation from that for static loading. Specifically, for the soil conditions which underlie the project site, a factor of safety of 1 or less represents a very high risk of sliding only during the ground shaking period. When the shaking ceases, movements should effectively also cease. This correlates with the observations of movements reported by a local resident upslope of the site after the 1965 earthquake. The actual amount of straining or displacement will depend on specific site and earthquake characteristics as well as the soil and ground water conditions. For the earthquake analysis, the shear plane was considered to have an additional strength component equal to 500 pounds per square foot of cohesion. This additional strength component is representative of the undrained soil conditions which would exist during the short -term cyclic loading. A factor of safety of 1.13 was computed using the indicated earthquake loading and undrained strength parameters. This value is considered, in general practice, to provide a level of risk comparable to a factor of safety of 1.5 for static conditions. SHALLOW- SEATED SLIDING Slope stability due to shallow - seated sliding was evaluated using an empirical /infinite slope approach. This approach is based on reviewing existing slopes at the site and then analyzing different water level conditions, assuming a uniform infinitely long slope of similar material. Slope con- figurations at the site vary from about 2H:1V (horizontal to vertical) to 4H:1V. Perched water levels (upper regime in Units A and B) are variable across the site, ranging from the surface in areas below springs or flow from old horizontal drains to 9 feet (Boring J), or deeper. In some areas, evidence of surficial creep, as expressed by bending in tree trunks as they have grown, on the flatter but wetter slopes, indicates a lesser degree of stability than steeper, well- drained slopes on the site. 14 GeoEngineers Incorporated The importance of control of water levels on near - surface stability is illustrated using a 3H:1V continuous slope, the soil strength (0 = 250) assigned to the upper soils in the analysis of deep- seated stability and varying the perched water level. The effect of water level conditions on the factor of safety against sliding (ratio of resisting force to driving force) is shown in the following table. Perched Water Level Factor of Safety at ground surface 0.7 6 feet below ground surface 1.1 12 feet below ground surface 1.4 The recommended final slopes for the site are 3H:1V or flatter. It is our conclusion that the stability of the slopes can be maintained at acceptable levels, provided that adequate drainage of the slopes is accomp- lished. The types of drainage facilities to be installed include an interceptor trench along the western property line, surface drains, a gully French drain, parking area French drains, subsurface wall drains and downspout drains. The extent of each of these facilities which should be installed to develop adequate drainage is discussed subsequently. The actual building loads will have a small favorable effect on the shallow slope stability, as the friction angle of the underlying soil is greater than the overall slope angle and the added vertical load will increase the resisting force more than the driving force will be increased (provided the load is applied slowly so that pore pressures are allowed to dissipate which is assumed to be the case for the type of construction and soils considered). There may be some destabilization of slopes during construction if slopes are oversteepened or adequate shoring is not used. Remedial measures including temporary backfilling, buttressing or otherwise increasing toe resistance may have to be initiated. Dynamic loading during an earthquake decreases the stability of slopes and may result in movement of any marginally stable slopes around the perimeter of the project. As described previously, the sliding should be limited to the duration of the earthquake. Resistance to sliding of individual structures requires analysis on a site - specific basis. This analysis should 15 GeoEngineers Incorporated be conducted by GeoEngineers, Inc. and the appropriate corrective measures recommended for inclusion in the design during the preparation of the final plans. CONCLUSIONS AND RECOMMENDATIONS GENERAL We conclude that development of the property as planned is feasible providing that maintenance of the WSDOT drain systems to the level required to maintain or improve present performance is accomplished and that the recommended near - surface drainage measures are accomplished as subsequently discussed on pages 22 and 23. Development of the site will be difficult due to the marginal stability and saturation of the near - surface soils. Close coordination between the earthwork contractor and the engineer will be required to see that our recommendations are diligently followed, as subsequently discussed on page 22. There are two principal mechanisms of slope instability which could affect the property. These include deep - seated sliding in a zone of soil from 30 to 50 feet below the surface and surficial sliding in the upper unit of soil, generally extending to a depth of about 10 to 12 feet below the present ground surface. The potential for movement of the hillside in the deeper zone of soils is largely controlled by the continued satisfactory performance of the vertical well /horizontal drain system which was installed during construction of Interstate Highway 5. It is also controlled to a lesser degree by the "Original Test Drains" which were installed south of the vertical well /hori- zontal drain system. From our review of available information, it appears that the overall site stability in the approximately 20 years since these drains have been constructed has been good and that the drainage system continues to be generally effective in preventing deep- seated movements. It is of prime importance, however, that both of the WSDOT drain systems remain fully operational. If the drainage systems should deteriorate so that artesian pressures can again increase beneath the hillside, the risk of deep - seated and extensive earth movements can be expected to significantly increase. 16 GeoEngineers Incorporated The second mechanism of shallow - seated movements is largely affected by surface runoff and near - surface infiltration of rainfall and runoff from higher ground. Based on the approximately 200 - foot -long scarp that was observed in 1982 and considered to be indicative of recent movement, it is evident that this potential for surficial movements is still relatively high in the southern portion of the property. We recommend that surface and near - surface drainage on the site be improved by constructing an interceptor ditch along the westerly limits of the property adjacent to Slade Way, together with installation of various drainage facilities in connection . with site grading and building construction which are discussed subsequently. The piezometers and slope indicator which have been installed as a part of this investigation form the basic components of an instrumentation program to monitor long -term behavior of the property. We recommend that this instrumentation program be expanded prior to construction. Additional slope inclinometers and piezometers should be installed at locations where they can be protected and remain functional, both during and following construction. A series of hubs should be installed above areas where cuts are planned. The hubs should be initialized (surveyed in) immediately and monitored on a regular basis thereafter. The system of piezometers and the inclinometer currently in place should also be maintained and monitored on a regular basis. Some of the new piezometers may have to be located to replace existing piezometers which may be lost in construction activities. A long -term monitoring program to be accomplished under the direction of (or by) our firm is recommended. We consider such a program essential to detect any changes in effectiveness of the WSDOT and on -site drainage systems so that early remedial action can be taken if needed. The extent of the recommended instrumentation program is described in a subsequent section. Earthwork on this property will be very difficult. We recommend that site grading be undertaken during the late summer -early fall months when the least amount of rainfall can be expected and surface runoff and seepage in the upper soil units should be diminished. Depending upon the overall construction schedule for the project, it may not be possible to accomplish all earthwork and drainage- related activities as well as foundation construction 17 GeoEngineers Incorporated in a single dry season. Therefore, we strongly recommend that construction activities be scheduled so that site grading, drainage installation and surface stabilization, if not final paving, are completed in any given area within a single construction season. Construction should also be phased, as described subsequently, to minimize the impact in any one area. No area should be left partially graded or without proper surface drainage, as this may- endanger the near - surface stability of that portion of the site if left through the wet seasons. Several of the planned structures are shown located above the existing sewer (see Figure 1). We understand that the sewer alignment may be changed so that it no longer is located below the structures. However, special foundation preparation procedures, as described on page 25, will be necessary along the sewer alignment to provide uniform bearing support for the structures. A major drainage way intersects the site in an east -west direction through the center of the site. It is important to maintain provisions for drainage along this gully alignment. Accordingly, we recommend that a French drain be installed along the base of the gully as shown in Figure 1 before any filling is accomplished. - EVALUATION OF I -5 DRAIN SYSTEM The operational life of horizontal drains is not well known. Depending on the soil type into which the drain is installed, the installation method and other factors, drains may operate satisfactorily for many years. However, drains are also known to silt up or clog due to corrosion or algae and bacterial growths within the slotted sections of pipe. This can result in major, if not total, loss of operating effectiveness after a few years. There appear to be no data available to assess periodic changes in performance of the WSDOT drain systems over the last few years. However, there are records of the water levels during the period December 1966 to June 1968 for several piezometers located immediately east of the site. There are also records of our piezometers from November 1983 through the present, and recent records of the water levels in three Shannon & Wilson piezometers 18 GeoEngineers Incorporated • and in the WSDOT wells (see Tables B -1 through B -3). Although the data are seasonal and precipitationvaries on an annual basis, we believe that there is a sufficient data base on which to evaluate the effectiveness and degradation of the WSDOT drainage system. The locations of the piezometers for which data are available during the period December 1966 to June 1968 are shown in Figure 2. The piezometric elevations before and after drain installation during this period as well as the March 1985 readings are tabulated below: PIEZOMETRIC ELEVATIONS (FEET) IN SHANNON & WILSON PIEZOMETERS PRE AND POST 1-5 DRAIN SYSTEM INSTALLATION Pre Drain Post Drain Piezo- Tip Water Water Elevation meter Elevation Elevation Dec. 66 Oct. 67 June 68 March 85 1A 85 155 101 92 90 93 1B 100 115 109 97 100 111 19 52 149 111 111 122 N/L 232 49 72 65 60 77 N/L 1 80 162 103 102 110 -139 2 86 153 130 122 123 N/L 3A 90 137 105 99 120 N/L N/L - Not able to be located. The tabulated data indicate that, with the exception of Piezometer 232, the piezometric surface was lowered between 15 and 65 feet approximately 3 years after installation. Since that time (June 1968) to the present, the water levels in the three Shannon & Wilson piezometers which we were able to locate indicate a rise of 3, 11 and 29 feet in Piezometers 1A, 1B, and 1, respectively. This indicates some degradation in the drain system; however, it may be related in part to the fact that the drains have not yet been cleaned out by WSDOT in 1985 (as of April). A similar comparison may be made of the water levels in Borings DM -1 and DM -3 from the Dames & Moore June 1961 report and Borings D and G in this study just inside the east property line of the site. This comparison is based on water levels at the time of the slide and at the present (March 19 GeoEngineers Incorporated 1985) time. Borings DM -1 and DM -3 both indicated artesian conditions shortly after boring completion. Borings D and G indicate water levels approximately 56 and 77 feet below the surface, which represents a in water level in this area. Finally, a comparison may be made between the substantial reduction existing water levels in the vertical wells and the elevations at which the horizontal drains intersect the wells. If the system is operating effectively, the water levels in the wells should be 1 to 2 feet higher (to account for head loss in the horizontal drain) than the intercept elevations. Comparison of the data in Tables B -3 and B -4 in Appendix B indicates that only a few wells, 19 and 22, 23 and 24, are operating effectively. The water levels in the other wells are generally on the order of 20 feet higher, and Wells 1, 2 and 3 up to 70 feet higher than the levels of the horizontal drains at the wells. The excess head in the wells may indicate clogging of the drains (increased head required to obtain flow), or it may simply indicate total clogging of the horizontal drains and reduced flow by alternate paths. In addition, Wells 1, 2 and 3 are not consistent with Wells 4 and 5, and Shannon & Wilson Piezometers 1, IA and 1B. It appears that, with the exception of the four wells noted, all of the horizontal drains and /or vertical wells are blocked to some degree. At this time (April 1985), it appears that the WSDOT drains have not been cleaned out for some time, based on the vegetative growth at the outlets. It is likely that maintenance of the drain system will affect the water levels in the wells and thus influence the conclusions to be drawn from the existing available data. performance of the WSDOT drain still significantly below the However, in spite of the indicated reduced system, the water levels at the site are levels that existed at the time of the slide and the system is, in our opinion, still effective in maintaining the water level in Unit C low enough for adequate (F.S.'1.6) deep- seated stability of the hillside. However, we believe that the stability of the project site is primarily dependent on the continued effective operation of the WSDOT drain system. It is improbable, in our opinion, that the water levels at the site will rise to critical levels in a short period of time (that is, in days or weeks) but, rather, over a period of months. With monitoring 20 GeoEngineers Incorporated at regular intervals, changes in water levels can be detected and appropriate remedial measures may be implemented. The multiple well groups and horizontal drains provide a redundancy to the system. Also, some of the flow appears . to have found other paths, possibly along the outsides of some drains, as evidenced by the flow through the panels at the retaining wall. We believe that it is essential that WSDOT expend effort to flush the horizontal drains and restore the effectiveness of the wells. If nothing is done, the drain system will continue to deteriorate, probably accelerating with time; however, if the drains are flushed and the wells cleaned and redeveloped if necessary, the system should continue to be effective for many years. Given the importance of the WSDOT drain systems on the stability of the project site, we recommend that the following repair work and maintenance procedures be implemented by WSDOT as soon as possible. o Clean out and flush the horizontal drains. o Clean out, flush and develop, if necessary, the 24 vertical wells. o Extract the pumps after flushing. (It is likely the pumps are silted in and may not be able to be extracted without flushing.) o Sound the depths of the wells. o Secure the top plates on the wells to prevent extraneous matter from being thrown into the wells. o Repair the "original test drain" system. o Locate and document the manifold outlets for the original test drains. o Monitor the flows from both systems of horizontal drains, as well as the piezometer levels, as discussed in the section on "Monitoring." SITE DEVELOPMENT The sequence of operations required to develop the site is critical to the successful completion of the project. In view of this condition, we have developed a general sequence for site development with regard to installation of instrumentation, drainage, site clearing and grading, and construction. Only minor deviations should be permitted from this sequence and then only with the approval of the engineer. 21 GeoEngineers Incorporated The recommended site development sequence is as follows: 1. Install additional instrumentation at least two months in advance of construction, and preferably as soon as possible, to establish the preconstruction data base. (See section on Instrumentation and Monitoring for details.) Monitor instrumentation on a regular basis, to be specified at the time of installation, before, during and after construction. 2. Construct interceptor trench along west property line (see later details in this section), install temporary drainage ditches in construction -free upslope areas, and install temporary erosion control measures to pick up concentrated surface water flow, locate and tightline appropriate on -site horizontal drains. 3. Establish access road, accomplish general site clearing, install gully French drain and accomplish general site grading. 4. Perform individual structure grading on a phased basis. Alternate building areas should be graded and with the number of sites prepared limited to the number for which foundation, wall construction and backfilling can be completed during the dry season. The approximate location of the interceptor trench is shown on Figure 1. The trench should be approximately 2 feet wide and not less than 7 feet deep. It should preferably extend to the top of the gray silt which varied between 7 and 12 feet in the three closest borings. The trench should be lined with a monofilament filter fabric such as Mirafi 140N, with not less than 2 feet of overlap of adjacent sections of the fabric. A 6 -inch smooth -wall perforated pipe should be fully bedded in a well - graded sand or clean gravel at the bottom of the trench. The remaining trench backfill should be clean, free-draining sand and gravel. The filter fabric should cover the free- draining fill with a fabric overlap of 12 inches below the surface and be covered with the silty native soil. A detail of the interceptor trench is shown in Figure 5. The approximate location of the gully French drain is shown in Figure 1. The drain should be installed from the downstream end working up the existing gully. The gully should be cleaned out of all organic material and debris for a width of at least 8 feet and a 3- foot-thick blanket of graded sand 22 GeoEngineers Incorporated • • and gravel filter placed in the gully. A smooth -wall, 8- inch - diameter perforated PVC pipe should be placed in a 12- inch -deep trench in the filter material and then covered with an additional 2 feet of the filter material. The top of the filter material should be at least 4 feet wide. The filter material should then be covered with filter fabric, as previously specified for the interceptor drain. Fill may then be placed in level lifts on either side of, and above, the filter material. We recommend that permanent French drains be installed along the upslope sides of all parking areas. These drains should be at least 5 feet below finished grades and should consist of perforated pipe fully bedded in a graded sand filter or in clean gravel which is, in turn, enclosed in a filter fabric envelope. The filter fabric should be installed with overlaps in the same manner as described above for the interceptor trench. The remaining trench backfill should consist of clean, free - draining sand and gravel. A similar drain should be installed in any wet areas to the west of the building units. Flow from these drains may be combined with flow from footing drains and downspouts for disposal in a storm drain system; however, the design of connecting pipes should be such to prevent backflow into sections of perforated pipe. We anticipate no impact on the WSDOT drain system from the proposed development if surface runoff is collected and routed off -site and surface water infiltration is minimized as recommended above. This conclusion is based on the fact that the WSDOT system services the lower aquifer and the barrier of lower permeability soils afforded by Unit B essentially precludes continuity between the upper and lower ground water regimes at the site. See Section on "GEOHYDROLOGICAL AND SURFACE WATER CONDITIONS" in this report. The ability to use the on -site soils for fill is expected to be limited. We anticipate that the soils in their natural state will be above optimum moisture for adequate compaction. In order to use these soils, drying will be necessary. Also, we recommend that only clean granular soils be used for fill behind retaining structures. While careful segregation of 23 GeoEngineers Incorporated the natural soils during excavation may provide some suitable backfill, we anticipate that much of the backfill behind the walls and for any areas of structural fill will have to be imported. Stockpiling should be limited as much as practical on the site to minimize potential impacts on slope stability and erosion. As noted, most of the on -site soil to be excavated will be unsuitable for backfill and should be immediately removed from the site. The earthwork should be sequenced to limit the size of any stockpiles. If stockpiles are required, they should be placed at the north end of the site. The size and height of the stockpiles should be determined on a specific basis as construction progresses and in coordination with our field representative. We recommend that temporary cut slopes be made no steeper than approxi- mately 1- 1 /2H:1V (horizontal to vertical) and be limited to 15 feet in height. The stability of these cut slopes will be relatively low. Our analyses indicate that the factor of safety under static, drained conditions will be on the order of 1.2 to 1.3,. assuming some short -term cohesion. Some sloughing or localized sliding should be anticipated, particularly where zones of seepage are encountered. When the excavations are made for the various buildings, we recommend that the construction be sequenced so that alternate building sites are excavated (for example, Sites 3, 5, 7, 9, etc.), retaining walls built and adequately braced, perimeter drainage installed, and backfill placed before beginning excavation for the intermediate buildings. Permanent cut or fill slopes should be established at no steeper than 3H:1V. Slopes should be seeded as soon as practical. Localized seeps which are not intercepted by the general drainage facilities may have to be drained and /or excavated and backfilled with gravel or crushed rock to resist erosion damage to slopes. STRUCTURAL FILLS AND PAVING All structural fill should be placed in relatively thin (8 to 10 inches). layers and uniformly compacted. Backfill against retaining walls, particularly those in the structures, should not .be overcompacted. A compaction of 24 GeoEngineers Incorporated 90 to 92 percent of the maximum dry density determined by ASTM D -1557 should be achieved. Fill beneath paved areas or forming slopes should be compacted to 95 percent of maximum density. We understand that access roadways and parking areas will be paved with asphaltic concrete. Prior to placing base course material, we recommend that the exposed subgrade be thoroughly proofrolled. Any soft, loose or wet areas should be excavated and replaced with clean granular fill if the natural soils cannot be satisfactorily recompacted. Based on the existing surficial wet conditions, it should be expected that overexcavation and replacement of on -site soils with imported granular fill will be necessary over much of the roadway and the parking area. Overexcavation of 12 to 18 inches may be necessary for roadways and parking areas to establish a stable subgrade. All fill placed below subgrade level should be compacted to at least 92 percent of maximum dry density (ASTM D- 1557). A pavement section of 4 -1/2 inches of clean pit run subbase, 1 -1/2 inches of crushed rock base and 2 inches of asphaltic concrete should be used. The extent of overexcavation and replacement of backfill along the existing sewer in areas to be occupied by buildings should be verified by examination during construction. As a worst case condition, the following may be necessary. Fill used to replace material excavated from the sewer line trenches should consist of clean granular soil. The existing backfill should be excavated from beneath the full building area and beyond for a distance of 4 feet on both sides to a depth of at least 5 feet below the bottom of the footing or to the top of the pipe, whichever is more shallow. The first foot of backfill over the pipe should be compacted to about 92 percent of maximum dry density and the remainder to 95 percent. RETAINING STRUCTURES Retaining structures will be required for all of the buildings based on present plans. The units will be stepped into the hillside so that each section of retaining wall will be no more than one story high. The setback between walls is expected to be 15 feet or more. In addition, retention of cut slopes and fill embankments will be required along portions of the parking areas and near Unit Nos. 1 and 2. 25 GeoEngineers. Incorporated We recommend that lateral pressures on the basement walls be determined using an equivalent fluid density of 35 pounds per cubic foot (pcf) times the height of the wall in feet. This value applies only if clean, lightly compacted granular backfill is used against the walls and if a perforated drain is installed along the base of the wall to prevent the buildup of hydrostatic pressure. This value also applies only where the ground surface behind the wall is level for a distance equal to the height of the wall. If a sloping ground surface exists closer to the wall, this value may have to be increased. Retaining structures along the parking area and elsewhere outside of the buildings could consist of gabion basket walls, reinforced earth structures, or conventional poured concrete walls. We recommend against the use of rockeries except possibly for protection of low (less than 5 feet) cuts into natural soils. Rockeries should not be used to retain fill embankments. Where backfill behind the walls is level, lateral pressures may be determined using an equivalent fluid density of 35 pcf times the height of the wall in feet. Where the surface slopes upward behind the wall, an increased lateral pressure must be used. If a backslope of 3H:1V exists, we recommend that the lateral pressures be determined using an equivalent fluid density of 60 pcf times the height of the wall in feet. We should review design criteria for other backslope configurations. Drainage of the backfill as well as cut slopes behind these retaining structures is critical to their stability. The lateral pressure design criteria given above is based on drained conditions. For solid structures, such as a poured wall, a zone of clean backfill and a perforated drain should be installed. If gabion basket walls are used, we recommend that filter fabric be placed beneath and behind the baskets to prevent the retained soils from washing into the relatively open work gabion rock. A perforated base drain located immediately behind the baskets is also recommended for gabion installations. Resistance to lateral loads on retaining structures may be developed by passive pressures and base friction. We recommend that passive pressures be determined using an equivalent fluid density of 200 pounds per cubic 26 GeoEngineers Incorporated • • foot. Base frictional resistance can be determined using a factor of 0.3 times the vertical downward component of long -term loading. These values incorporate a factor of safety of about 1.3. FOUNDATION DESIGN We recommend that the lowest floor grade of each structure be established at an elevation such that a shallow foundation system will bear directly on natural soils below the topsoil layer. We recommend specifically against supporting structures on a combination of cut and fill. It may be necessary to overexcavate and replace some of the native materials if soft, wet conditions are encountered during construction. This will probably occur all along the sewer line, as previously discussed. Overexcavation /replacement will be satisfactory providing that any fill which is placed does not extend above the original ground surface elevation. We suggest the use of a foundation system consisting of a thickened slab system that will provide more rigidity and resistance to slight differential movements across a structure than that.which would be provided by continuous wall footings and a slab -on- grade system. The foundation system should consist of thickened edges around the perimeter of the slab and thickened sections beneath bearing walls within the buildings. The thickened slab system should have continuous reinforcing consisting of reinforcing bar rather than steel mesh. The thickened edge sections should extend at least 18 inches below lowest adjacent finished grade and should have a base width of at least 18 inches. The thickened edge portion of this foundation system may be proportioned using a bearing value of 2,000 pounds per square foot. This value applies to the total of all design loads including wind or seismic, but excluding the weight of the footing and any overlying backfill. Care must be taken in preparing the subgrade for the thickened slab foundation system to avoid disturbance to the bearing materials. Any seepage which is encountered should be collected and diverted from the building area. The prepared bearing surfaces should be examined by one of our staff to determine that suitable preparation has been accomplished. It may be necessary to move and replace soft, wet or otherwise disturbed soils and to install localized drainage facilities to handle any seepage within the building area proper. Any soft soil should be replaced with clean granular 27 GeoEngineers Incorporated fill compacted to 95 percent of the maximum dry density. We recommend that the bearing surface be protected from disturbance during reinforcing steel placement and concrete pouring by placing .a 4- inch -thick layer of clean sand or sand and gravel compacted to a moderately dense state. Over - compaction should be avoided to prevent pumping if the subgrade soils are wet. We recommend that foundation drains be installed along the outside of the thickened edge sections of the foundation system. These drains, together with the drains for the retaining wall sections of the buildings, should be connected to tight drain lines along the east property lines so that flow can be conducted off -site for disposal in a means which will not adversely affect the stability either of this site or the hillside to the east. Settlement of the foundation system designed and installed as recommended above is expected to be relatively small, probably on the order of 1/2 to 3/4 of an inch. Some differential settlement may occur across units because of the differences of relief of overburden pressure resulting from the varying depths of excavation to establish lowest floor grade levels. INSTBDMENTATION AND MONITORING The purpose of the instrumentation program and long -term monitoring at the site is to establish base line data for the performance of the horizontal drain system and, hence, to set up an early warning system if the water levels in the slope start to rise. The instrumentation program which we envision as being appropriate includes piezometers located in areas where they will not be damaged by site grading and construction activities, a network of inclinometers to monitor any hillside movement, survey stakes on slopes which are regraded or which have cuts made at the toe of the slope, and benchmarks established on building foundations as they are con- structed. We recommend installation of at least 6 additional inclinometers, 4 along the easterly boundary of the project site and 2 along the upper portion of the site, one to the north and one to the south of Inclinometer F. These inclinometers will be installed to function as piezometers as well. 28 GeoEngineers Incorporated • • The piezometers and inclinometers should be installed at least two months prior to, and preferably as soon as possible, to start obtaining baseline data. The number of additional piezometers installed may vary, depending on how many of the existing ones can be saved. It appears probable that 4 or 5 of the existing piezometers will be lost (D, G, H, J, and K). We recommend installation of 6 to 10 shallow piezometers (i.e., to depths of approximately 20 to 25 feet each) to monitor water levels in the upper soil strata and 3 or 4 additional deep piezometers to supplement the piezometric data developed from the inclinometers. The shallow piezometers will monitor the effectiveness of the westerly interceptor drain and other site drainage facilities. In addition to the long -term instrumentation, slope monitoring stakes should be installed in areas where grading involves cuts into the near - surface soils. These should consist of one or more rows of stakes on 20- to 40 -foot centers from which elevation and alignment records can be maintained to determine whether or not any movements occur in the surficial soils. If any movements are detected, remedial measures will be able to be undertaken promptly. As building foundations are placed, permanent reference points should be established at least on the four corners of each building and the elevations recorded. Future elevation readings of these points will then provide a basis for determining any elevation changes which may occur due to foundation settlements or hillside movements. If hillside movements should occur, they would also be reflected in the inclinometer readings. We recommend that the monitoring program initially require that inclino- meters and piezometers be monitored monthly during construction, bi- monthly between construction seasons and twice a year, in February and August, after completion of the project. More frequent monitoring may be required, depending on the weather. Slope monitoring stakes should be surveyed on an every- other -day basis while grading activities are underway in the immediate area and monthly during periods of construction until project completion. It is anticipated that slope stake systems will be lost in final landscaping. 29 GeoEngineers Incorporated • • Benchmarks on building foundations should be initialized as soon as they are set and read once when each building unit is about 50 percent complete, once upon completion, and annually thereafter. A detailed action plan should be prepared so that it can be promptly implemented in the event of significant changes in water levels or indications of slope movement. The plan should include trigger levels for the inclinometers and piezometers, and specific actions by responsible parties should be established. We recommend that an overall rise in water level of ten (10) feet in the lower aquifer (Unit C), as measured by the on -site piezometers, be taken as a "trigger" level for remedial action. Other trigger levels related to the WSDOT drain systems should be established once they have been cleaned out and are working properly. Trigger levels for the inclinometers should be based on an increase in displacement of more than 0.2 inches per year. The action plan should consist of the following: 1. Notifying our firm immediately. 2. Analysis of the data by our firm to establish the probable cause of the changed conditions at the site. 3. Developing recommendations by our firm for obtaining additional information if necessary and to implement the necessary remedial measures. These recommendations may include: o Obtaining additional information such as surveying the settlement hubs at the site. o Increasing the monitoring frequency. o Maintenance or restoration of the on -site drainage or WSDOT drain systems. o Installation of new horizontal drains on or off site (WSDOT right -of -way). o Pumping the vertical wells in the WSDOT system. o Implementing localized slope stabilization measures. It should be kept in mind that modifications to the number, locations, and, possibly, types of instrumentation as well as modification in the frequency of monitoring may be appropriate as project construction progresses. 30 GeoEngineers Incorporated For this reason, it is imperative that GeoEngineers have a continuing parti- cipation on the project to coordinate installation of the instrumentation, to recommend changed locations or additional points, to monitor the instrumen- tation, and to interpret the data and advise on the performance of the hillside and recommend what, if any, remedial measures may be appropriate. USE OF THIS REPORT We have prepared this report for use by Dr. H.M. Allenbach and members of the design team. This report should be provided to prospective contractors for their bidding or estimating purposes. Our report, conclusions and interpretations should not be construed as a warranty of the subsurface conditions. As noted previously, we have used data developed by our firm as well as by others at widely spaced locations. If there are changes in the loads, grades, location, configuration or type of construction planned from that which we have been provided, the conclusions and recommendations presented may not be applicable. If design changes are made, we request that we be 'given the opportunity to review our conclusions and recommendations and to provide a written modification or verification. When the design has been completed, we recommend that the appropriate construction drawings and specifications be reviewed by our firm to see that our recommendations have been interpreted and implemented as intended. The earthwork and site preparation activities are of critical importance to the success of this project. GeoEngineers, Inc. must be involved in the construction monitoring and field to see that our recommendations are properly interpreted and implemented. If we are not involved in the con- struction phase of the project, we disclaim any liability for the manner in which the construction is accomplished or the results thereafter. The scope of our services does not include services related to construction safety precautions and our recommendations are not intended to direct the contractor's methods, techniques, sequences or procedures, except as specifi- cally described in our report for consideration in design. There are probable variations in subsurface conditions between the explorations and also with time. A contingency for unanticipated conditions should be included in the budget and schedule. The construction monitoring, 31 GeoEngineers Incorporated testing and consultation by our firm will provide the opportunity to confirm that the conditions encountered are consistent with those indicated by the explorations, to provide recommendations for design changes should the conditions revealed during the work differ from those anticipated, and to evaluate whether or not earthwork and foundation installation activities comply with contract plans and specifications. Within the limitations of scope, schedule and budget, our services have been executed in accordance with generally accepted practices in this area at the time the report was prepared. No other warranty, express or implied, should be understood. The conclusions and recommendations in this report should be applied in their entirety. If there are any questions concerning this report or if we can provide additional services, please call. Respectfully submitted, .• ., -.1 i, I• j•, °Se GeoEngineers, Itic. ,t i Of it F • t o GMD:JKT:da File No. 523 -02 April 25, 1985 ord6n M. Denby Engineer Se J . Tuttle incipal 32 toy T U 7 ASH, ; % -, t 4 Z\1 s — eSS/pNAI 0 ,1'� GeoEngineers Incorporated FIGURE 1 SLADE WAY Q. ® DM �C i 7 / IP J PARKING 1 PROPOSED INTERCEPTOR TRENCH PROPOSED FRENCH DRAIN \,‘ %0 4*, „ ►V DM -1 _ 1� • H� PARKING 7 DM- 13 14 r 1 r 15 RLICRINCL: UkAWINI, LNIIIILU "vALIEY VICW ESTATES I BY W117�LY L UAM INL, DAIED 5/5/82 5 ° 3 1 ‘ ' ' ` N PJF -VE 530.0 1 12" DIAMETER DUCTILE IRON SEWER LINE NOTE: PROPOSED INTERCEPTOR TRENCH TO BE LOCATED IN THE FIELD. TRENCH TO BE ALIGNED ALONG CONTOUR AND DRAIN FROM NORTH TO SOUTH. PROPOSED FRENCH DRAIN TO BE LOCATED IN FIELD IN EXISTING DRAINAGE GULLY. 40-D EXPLANATION: BORING LOCATION AND LETTER DESIGNATION UM -1 UAMI-S E MUURL INVEST ILATIUN 1961 U 80 I I,O SCALE IN ELET GeoEngineers Inc. 1 SITE PIAN FIGURE 3 Reference: Drawing entitled "Plan of Slide Area with Reconnaissance Data and Proposed Drainage" by Shannon 6 Wilson, dated June, 1964. Legend: Marsh Areas with Surface Seepage OD Seepage Zones Horizontal Drains Installed by Others 0.4 gpm Flow Measured May 12, 1964 Subdrains to be Installed Under Existing Contract ® Slope Indicator Installed by Shannon Wilson, Inc. in June, 1964 Drill Hole Made by Shannon 6 Wilson in May —June, 1964 Q Observation Well Installed by the State ® Slope Indicator Installed by the State Boring Made by Dames 6 Moore, April,• 1961 0 50 100 150 1 1 1 Scale In Feet GeoEngineers Inc. EXISTING ON SITE HORIZONT4:. DRAIN FIGURE 4 ELEVATION IN FEET A 240- 200- 160- 120- 80- PROPERTY LINE 0 z Z 0 m z Z 0 m ESTIMATED PERCHED WATER TABLE WATER TABLE IN UNIT C r Vdiralt UNIT C L) 0 z U' _ z 0 o m�� z O Z to. �� „... ..,,,eiimir ,,,, ,...- Mlt� PROPERTY LINE UNIT A GRAY SILTY SAND AND SANDY SILT (COLLUVIUM AND SLOPE DEBRIS) UNIT B GRAY SILT WITH INTERBEDDED WET SILTY SAND TO SAND LAYERS; SLICKENSIDES TOWARDS BASE OF UNIT. UNIT C GRAY SAND AND GRAVEL INTERBEDDED WITH SILT LAYERS; .WET. A I A -240 -200 -160 -120 -80 ELEVATION IN FEET HOkIZONTAL SCALE: 1" - 40' ( : 1 u 1 1 11l. W 1 1 A GeoEngineers ” Inc . 1.1 )1 ,11.11UI1 A -Al 5z� -OL I-1J': WJ 9•z05 FIGURE 5 WELL GRADED SAND OR CLEAN GRAVEL BACKFILL NON -WOVEN FILTER FABRIC MINIMUM WIDTH =2' 6" PERFORATED PIPE MINIMUM DEPTH =7' GeoEngineers Inc. SCHEMATIC OF PROPOSED INTERCEPTOR DITCH • • APPENDIX A FIELD EXPLORATIONS AND LABORATORY TESTING FIELD EXPLORATIONS Subsurface soil and ground water conditions at the site were explored by drilling 8 borings at the locations shown on the Site Plan, Figure 1. The borings were generally terminated in the waterbearing sand and gravel layer. Total lineal footage was 572 feet. The borings were drilled using a truck- mounted, 4 -inch inside diameter, hollow -stem auger drill rig. Observation wells consisting of 1/2 -inch PVC pipe with a slotted tip were installed in all borings, except Boring F, after drilling was completed. A double installation was used in Boring J where a well tip was installed at the bottom of the, hole and at the contact with the silt at 20 feet depth. A slope inclinometer casing was installed in boring F in order to permit measurement of any future movements in the slope. A geotechnical engineer from our staff was present during the explora- tions. Our representative assisted in locating the borings, obtained repre- sentative soil samples, examined and classified the soils encountered, observed ground water conditions and maintained a detailed log of each exploration. The soils were classified in accordance with the Unified Soil Classification System which is described on Figure A -1. The logs of the explorations are presented on Figures A -2 through A -17. Relatively undisturbed soil samples were obtained from the borings using a heavy -duty sampler with 2 -1/2 -inch brass liner rings. The sampler was driven using a 250 -pound hammer falling a distance of 30 inches. The driving resistance for one foot of penetration is noted on the logs adjacent to the sample notations. All samples were sealed in containers to limit moisture loss, labeled and taken to our laboratory for further examination and testing. LABORATORY TESTING Selected samples were tested to determine the field moisture and density and strength characteristics. The moisture- density data are presented on the logs of the explorations next to the appropriate sample notations on Figures A -2 through A -18. A- 1 GeoEngineers Incorporated BORING LOG AND SAMPLE DA A KEY DRIVEN SAMPLES BLOWS REQUIRED TO DRIVE SAMPLER MOISTURE CONTENT 28 11.2% 111 • DRY DENSITY ® IN PCF ❑ ONE FOOT OR INDICATED PENETRATION USING POUND HAMMER FALLING INCHES "P" INDICATES SAMPLER PUSHED WITH WEIGHT OF HAMMER INDICATES LOCATION OF UNDISTURBED SAMPLE INDICATES LOCATION OF DISTURBED SAMPLE INDICATES LOCATION OF SAMPLING ATTEMPT WITH NO RECOVERY OTHER TYPES GRAPHIC LOG OF SAMPLES SM ~" LETTER SYMBOL SOIL TYPE DISTINCT CONTACT BETWEEN SOIL STRATA GRADUAL CHANGE BETWEEN SOIL STRATA INDICATES LOCATION OF THIN WALL, PITCHER, OR OTHER TYPES OF SAMPLES (SEE TEXT) / / BOTTOM OF BORING UNIFIED SOIL CLASSIFICATION SYSTEM MAJOR DIVISIONS LETTER SYMBOL DESCRIPTIONS COARSE SOILS MORE /INN sox OF MATERIAL IS Lem TWW ND. 200 SIEVE SIZE GRAVEL AND GRAVELLY ICRE T)W$ 50% fT C melt - ON P°. ♦ SIEVE CLEAN GRAVELS (LITTLE OR NO FINES) GW MELM-X s.GR ELS. GRAV L-SME"a° GP PaDRLr�,AADEO GRAVELS. GRAVEL- SAND MIXTURES. LITTLE OR NO FINES GRAVELS WITH FINES (APPRECIABLE AMOUNT If FINES) GM SILTY GRAVELS. GRAVEL- 5000SILT MIXTURES GC CLAYEY GRAVELS. GRAVEL -SAM° -SILT MIXTURES SAND AND SANDY SOILS CCOARSE FMC_ TIM EOWZI CLEAN SANDS (LITTLE CR ND FINES) SW VELL GRACED SANDS. GRAVELLY SAN'S. LITTLE oR ND F,NEs SP POORLY- GRADED S*°S. GRAVELLY SAN'S. LITTLE DR ND FINES SANDS WITH FINES )APPRECIABLE AMOUNT OF FINES) SM SILTY SANS. SAND-SILT MIXTURES i SC CLAYEY SANDS. S ID -CLAY MIXTURES FINE GRAINED SOILS MERE THAN CF E1R' IS ( 200 SIEVE SIZE SILTS AND CLAYS LIOUID LIMIT LESS THAN 50 ML INORGANIC SILTS. AND VERY FINE SANDS. SA10X5 c CLAYEY SILLTSCVIMM SLIGHT PLASTICITY CL INORGANIC CLAYS DF LOM TO NEDI'7 PLASTICITY. GRAVELLY CLAYS. sAov CLAYS. SILTY CLAYS. LEAN CLAYS OL OLGNvIC SILTS AN) ORGANIC SILTY CLAYS OF NOM PLASTICITY SILTS AND CLAYS . LIOUID LIMIT GREATER THAN 50 MH 1NORGWIC SILTS. MICACEOUS p1 DIATO- ' FINE SAND CO SILTY SOILS CH DORGA RIC CLAYS CF NIGH PLASTICITY FAT CLAYS OH ORGANIC CLAYS CF MEOILDA TD NIGH PLASTICITY. ORGANIC SILTS HIGHLY ORGANIC SOILS PT PEAT. P&MIS. SMNi SOILS wITM NIGH ORGANIC CONTENTS NOTE. DUAL SYMMS INDICATE BOOEPIINE 501L CLASSIP ICATIC% GeoEn ineers Inc. 9 UNIFIED SOIL CLASSIFICATION SYSTEM AND KEY TO SAMPLE DATA BORING C ELEVATION: 237.1 FEET GRAPHIC TEST DATA LOG FIGURE A -2 DATUM: CITY OF TUKWILA DESCRIPTION 15 - 20 25-1 30- 35- 40— 23.8% 99.111 9 1.9% 91.5 II 29 31.2% 91.7 II 28.3% 94.2 32 24.5% 100.9 II 53 24.6% 100.5 II 54 .9% 98.31 53 6" .6% 122.8 II Sit BROWN SILTY SAND WITH GRAVEL (STIFF, MOIST) ML GRAY SANDY SILT WITH RUST STAINS (STIFF, MOIST) ML GRAY SILT WITH WET FINE SANDY SILT INTERBEDDED (STIFF, MOIST) SLICKENSIDES SLICKENSIDES FINE SANDY SILT LENSES SL I CKENS 1 DES SP GRAY FINE TO MEDIUM SAND (MEDIUM DENSE TO TO DENSE, MOIST) HIT GRAVEL AT 38 FEET FOR 2 FEET, THEN SANDY, THEN BACK INTO GRAVEL *SEE KEY FOR EXPLANATION OF SYMBOLS GeoEngineers Inc. LOG OF EXPLORATION '40 BORING C (CONTINUED) GRAPHIC TEST DATA LOG 45 55 6 0 -' 65" 70 75 51 6n 14.3% 116.111 93 34.9% 82.71 50 4" 26.0% 99.011 50 5" 26.6% 98.711 50 53 16.1% 119.21 89 6" 4.0 159.8 II 7.1% 60 6" ML SM DESCRIPTION FIGURE A -3 SM ML SM ML GM • GRAY GRAVELLY SANDY SILT TO SILTY SAND WITH WET FINE TO MEDIUM SAND LENSES (STIFF TO DENSE, MOIST) GRAY FINE TO MEDIUM SAND WITH SOME SILT, ORGANIC FRAGMENTS AND MICA (DENSE, MOIST TO WET) SHOE CONTAINED WOOD GRAY FINE SANDY SILT (STIFF, MOIST TO WET) GRAY GRAVELLY SILT WITH FINE TO MEDIUM SAND LENSES AND OCCASIONAL ORGANIC FRAGMENTS (STIFF TO VERY STIFF, MOIST) GRAVEL AT 64 FEET BORING COMPLETED AT 73i FEET ON 10/20/83 PIEZOMETER INSTALLED AT 732 FEET ON 10/20/83 GROUND WATER LEVEL AT 64 FEET DURING DRILLING *SEE KEY FOR EXPLANATION OF SYMBOLS GeoEngineers Inc. LOG OF EXPLORATION RAH:(MD:nA DEPTH IN FEET BORING D ELEVATION: 178.8 FEET *GRAPHIC *TEST DATA LOG . DESCRIPTION FIGURE A -4 10 15-- 20 25- 3 0 -- 35- 40- 9 26.6% 91.111 14 30.9% 88.811 36 29.6% 93.111 19 23.5% 100.91 32 18.8% 110.61 32 9.7% 110.91 50 511 9.6% 50 2" 6.40 142.4® ML BROWN AND GRAY SILT WITH ORGANIC FRAGMENTS AND ROOTS (STIFF, MOIST TO WET) (FILL ?) ML GRAY SILT WITH SOME RUST STAINS (STIFF, MOIST) ML SM LAMINATIONS DIPPING AT 20 °, OCCASIONAL CALCIUM CARBONATE CONCRETION GRAY SILT WITH POCKETS OF GRAY FINE SAND (STIFF, MOIST) OCCASIONAL GRAVEL WITH FINE SANDY SILT LENSES SLICKENSIDES GP GRAY SANDY GRAVEL (DENSE, WET) *SEE KEY FOR EXPLANNATION OF SYMR01.S GeoEngineers Inc. LOG OF EXPLORATION QAM:cmn:DA 40 BORING D (CONTINUED) *GRAPHIC *TEST DATA LOG DESCRIPTION FIGURE A -5 45 - 60 - GP 78 6" 7.3% 139.2 50 3" 11.5% 50 GP GRAY SANDY GRAVEL WITH SOME SILT (DENSE, WET) 4" GM X0.6% 130.80 19.7% 100 T GM GRAY SILTY SANDY GRAVEL (DENSE, WET) 7 FEET OF HEAVE AT 57i FEET BORING COMPLETED AT 58i FEET ON 10/19/83 PIEZOMETER INSTALLED AT 58i FEET ON 10/19/83 *SEE KEY FOR EXPLANATION OF SYMROLS GeoEngineers Inc. LOG OF EXPLORATION RAW(MD:DA 0 BORING F ELEVATION: 237.0 FEET *GRAPHIC *TEST DATA LOG DESCRIPTION FIGURE A -6 15- 20- 25- 30- 35- 40- SM 5 43.5% 70.911 7 35.0% 86.211 6 ML 27.4% 96.111 14 27.0% 97.911 12 30.3% 93.811 ML 35 30.6% 92.211 51 30.1% 92.511 65 24.3% 101.911 ML ML BROWN- BLACK -GRAY SILTY SAND WITH ORGANICS (MEDIUM DENSE, MOIST TO WET) (FILL) GRAY SAND WITH MICA (MEDIUM DENSE, MOIST TO WET) GRAY FINE SANDY SILT (SOFT, WET) GRAY SILT WITH A TRACE OF CLAY WITH SLICKENSIDES AND SOME WET FINE SANDY SILT LAYERS (MEDIUM STIFF, MOIST) GRAY SILT AND FINE SANDY SILT LENSES AND SLICKENSIDES (STIFF, DAMP) SLICKENSIDES GRAY FINE SANDY SILT WITH SLICKENSIDES (STIFF, DAMP) *SEE KEY FOR EXPLANATION OF SYMBOLS GeoEngineers Inc. LOG OF EXPLORATION 40 BORING F (CONTINUED) *GRAPHIC *TEST DATA LOG DESCRIPTION FIGURE A -7 76 26.5% 97.311 45- 34 20.6% 109.51 w 50 50 5 13.5% 122.611 55 ML ML SP 50 2" GM 9.1% 117.611 ML 60- 50 11" 1 65- GM SOME FINE SANDY SILT LENSES GRAY SILT INTERBEDDED WITH FINE TO MEDIUM SAND (STIFF TO DENSE, MOIST TO WET) INCREASING GRAVEL CONTENT WITH DEPTH GRAY SANDY SILTY GRAVEL TO SANDY GRAVELLY SILT (DENSE TO VERY DENSE, MOIST TO WET) GRAY SANDY SILTY GRAVEL (VERY DENSE, MOIST TO WET) BORING COMPLETED AT 63 FEET 1 INCH ON 10/21/83 GROUND WATER LEVELS MEASURED AT 10.5 AND 53 FEET DURING DRILLING INCLINOMETER CASING INSTALLED AT DEPTH OF 63 FEET 1 INCH ON 10/21/83 *SEE KEY FOR EXPLANATION OF SYMBOLS GeoEngineers Inc. LOC OF EXPLORATION RA.:GMn'DA 0 5 BORING G ELEVATION: 179.2 FEET *GRAPHIC *TEST DATA LOG 15- 20- 25- 30- 35- 40- 20 11.2% 105.011 SM SM DESCRIPTION FIGURE A -8 BROWN GRAVELLY SILTY SAND WITH SOME COBBLES (MEDIUM DENSE TO DENSE, MOIST) BROWN AND GRAY RED - STAINED GRAVELLY SILTY SAND (MEDIUM DENSE, MOIST) ML GRAY SILT WITH FINE SANDY SILT LENSES 20 (STIFF, MOIST) 25.9% 98.71 15 32.0% 90..311 16 25.7% 99.811 8 35.0% 86.511 18 32.3% 90.811 31 28.7% 92.711 57 27.7% 95.911 FINE SANDY SILT LENSES (MOIST TO WET) SLICKENSIDES DIPPING AT 45° FINE SAND LENSES GRADES TO VERY STIFF AND DAMP SLICKENSIDES SLICKENSIDES WITH FINE SANDY SILT LENSES *SEE KEY FOR EXPLANATION OF SYMBOLS GeoEngineers Inc. LW; OF EXPLORATION DAH:rm^:Dt 40 *GRAPHIC *TEST DATA LOG • FIGURE A -9 BORING G (CONTINUED) DESCRIPTION 45 - w 50- z a 60- 65 - 70 75 80 - 32 25.1% 99.811 42 25.2% 100.311 21 24.8% 101.111 63 6" 24.0% 101.211 86 6" 12.4% 125.3Ig 50 1" 13.7% 121.9® 70 6" 26.3% 99.41 50 25.3% 96.51 ML ML SP SM GM SP HIT GRAVEL AT 45 FEET GRAY SILT WITH FINE SANDY SILT AND FINE TO MEDIUM SAND LENSES (STIFF., MOIST) SLICKENSIDE GRAY FINE TO MEDIUM SAND WITH GRAY SILT INTERBEDDED (MEDIUM DENSE, WET) INCREASING GRAVEL CONTENT GRAY SILTY SANDY GRAVEL (DENSE, MOIST TO WET) 2 FEET HEAVE AT 67.5 FEET GRAY FINE TO MEDIUM SAND WITH SOME GRAVEL AND OCCASIONAL GRAY SILT LAYER (DENSE, WET) BORING COMPLETED AT 78i FEET ON 10/18/83 GROUND WATER LEVEL AT 49i FEET DURING DRILLING PIEZOMETER INSTALLED AT 78' FEET *SEE KEY FOR EXPLANATION OF SYMBOLS GeoEngineers Inc. LOG OF EXPLORATION 0 BORING L ELEVATION: 207.5 FEET *GRAPHIC *TEST DATA LOG DESCRIPTION FIGURE A -10 5-' 20 30 40 18 9.8% 122.511 6 35.4% 84.911 6 33.4% 89.111 8 26.1% 98.011 22 30.7% 92.211 34 29.9% 93.411 51 27.4% 97.011 43 27.6% 96.411 SM ML BROWN GRAVELLY SILTY SAND (MEDIUM DENSE, MOIS -T) GRAY SILT WITH REDDISH BROWN STAINS AND FINE SAND INTERBEDDED (SOFT, MOIST) r GRADES TO MEDIUM STIFF FRACTURES GRADES TO STIFF 1/8 INCH SAND LENS AT 281 FEET GRADES TO VERY STIFF, DAMP SLICKENSIDE AT 371 FEET *SEE KEY FOR EXPLANATION OF SYMROT.S GeoEngineers Inc. LOG OF EXPLORATION FIGURE A -11 40 *GRAPHIC *TEST DATA LOG BORING L (CONTINUED) DESCRIPTION 45 — 50- z ca 55 60— 65— 73 22.3% 104.41 86 25.8% 98.41 32 23.5% 104.41 52 6" 13.5% 125.91 ML SM GRAY INTERBEDDED SILT AND FINE SAND (VERY STIFF, ML MOIST) FRACTURES AND SLICKENSIDES SP GRAY FINE SAND (LOOSE TO MEDIUM DENSE, WET) ▪ G• M GRAY SANDY GRAVEL WITH A TRACE TO SOME SILT HEAVE AT 611 FEET. BORING COMPLETED AT 63 FEET ON 10/14/83 GROUND WATER LEVEL ESTIMATED AT 49 FEET DURING DRILLING PIEZOMETER INSTALLED AT A DEPTH OF 63 FEET ON 10/14/83 *SEE KEY FOR EXPLANATION OF SY1+1,1O L GeoEngineers Inc. LOG OF EXPLORATION DEPTH IN FEET 0 BORING H ELEVATION: 229.5 FEET *GRAPHIC *TEST DATA LOG DESCRIPTION FIGURE A -12 5- 10- 15- 2 0- 25- 30- 35- 40-• 6 SP SP BROWN SILTY FINE SAND WITH GRAVEL (MEDIUM DENSE, MOIST) (FILL) TAN TO BROWN FINE SAND WITH RUST STAINS (LOOSE, MOIST) 21 30.5% 90.811 ML GRAY SILT. WITH SAND LENSES (STIFF, MOIST) 24 30.2% 92.411 22 28.6% 95.211 30.9% 92.21 24 25.6% 100.411 29 26.2% 99.711 21 28.8% 95.411 7 /WITH A TRACE OF CLAY *SEE KEY FOR EXPLANATION OF SYMBOLS GeoEngineers Inc. LOG OF EXPLORATION FIGURE A -13 DEPTII IN FEET 40 *GRAPHIC *TEST DATA I.UG BORING H (CONTINUED) DESCRIPTION 45- 50-1 55~ 60- 65' 25 33.1% 90.111 34 29.9% 93.511 46 28.0% 95.91 66 28.2% 96.111 93 22.6% 102.811 WITH SAND INTERBEDDED, SLICKENSIDES, AND VERTICAL SAND /SILT CONTACT IN SAMPLE GRAY SILT INTERBEDDED WITH SAND VERTICALLY GRAVEL OBSERVED BY DRILLER GRAY SILT INTERBEDDED WITH SAND LENSE AT 70 DEGREE DIP GRAVEL IN BARREL ABOVE SAMPLE BORING COMPLETED AT 621 FEET ON 10/13/82 GROUND WATER OBSERVED AT 55 FEET DURING DRILLING PIEZOMETER INSTALLED AT 62i FEET *SEE KEY FOR EXPLANATION OF SYNROLS GeoEngineers Inc. LOG OF EXPLORATION BORING J ELEVATION: 195.4 FEET *GRAPHIC *TEST DATA LOG DESCRIPTION 20- 25 - 30 35- 4 0 — 50 6' 23.5% 87.01 7 30.2% 90.4. 5 28.2% 95.81 32.2% 17 • 18 31.6% 91.011 18 31.8% 88.011 24 32.4% 90.011 22 32.3% 90.011 SM BROWN GRAVELLY SILTY SAND WITH WOOD FRAGMENTS (MEDIUM DENSE, MOIST) ML GRAY SILT INTERBEDDED WITH SAND LENSES (SOFT, MOIST) r GRADES TO STIFF WITH SLICKENSIDES AND FRACTURING FRACTURES SLICKENSIDES OCCASIONAL BROWN STAINS SLICKENSIDES *SEE KEY FOR EXPLANATION OF SYMBOL~ GeoEngineers Inc. LOG OF EXPLORATION FIGURE A -1 DEPTH IN FEET 40 *GRAPHIC *TEST DATA LOG BORING J (CONTINUED) DESCRIPTION 45- 50 - 55-1 60- 65- 70 75 - 80- 25 30.9% 92.611 23 32.0% 90.111 29 33.7% 89.011 23 28.7% 93.711 96 23.6% 100.911 47 25.9% 89.811 106 18.3% - 106.111 59 6" 18.7% 110.211 ML ML GP WITH SLICKENSIDES AND BROWN STAINS LARGE SLICKENSIDE GRADES TO VERY STIFF FEW SLICKENSIDES WET SAND LENSES AND RUST STAINS GRAY SILT WITH SOME GRAVEL, SLICKENSIDES, RUST STAINS, AND SAND LENSES (VERY STIFF, DAMP) HIT GRAVEL BETWEEN 77 TO 80 FEET *SEE KEY FOR EXPLANATION OF SYMBOLS GeoEngineers Inc. 1 LOG OF EXPLORATION FIGURE A -16 80 85 w z a A *GRAPHIC *TEST DATA LOG f1L F SP BORING J (CONTINUED) DESCRIPTION GRAY FINE TO MEDIUM SAND (MEDIUM DENSE, WET) HEAVE AT 82i FEET BORING COMPLETED AT 84 FEET ON 10/15/83 GROUND WATER LEVEL ESTIMATED AT 49 DURING DRILLING PIEZOMETER INSTALLED AT A DEPTH OF 82i FEET AND 20 FEET *SEE KEY FOR EXPLANATION OF SYMBOLS GeoEngineers Inc. 1 LOG OF EXPLORATION FIGURE A -17 BORING K ELEVATION: 175.0 FEET *GRAPHIC *TEST DATA LOC DESCRIPTION w 10- z 2 0 - 25" 30- 35 40- 13 21.7% 99.611 9 26.3% 97.011 8 34.10 87.711 10 28.3% 97.011 5 35.5% 87.31 20 29.8% 92.411 20 26.4% 93.511 36 26.1% 98.211 SM BROWN GRAVELLY SILTY SAND WITH RED AND DARK BROWN STAINS (LOOSE TO MEDIUM DENSE, MOIST) ML GRAY SILT WITH SAND LENSES AND RUST STAINS (STIFF, MOIST) MOTTLED APPEARANCE GRADES TO SOFT AND WET SLICKENSIDES GRADES TO STIFF AND MOIST TO WET SLICKENSIDES AND BROWN STAINS SLICKENSIDES AND BLOCKY FRACTURES *SEE KEY FOR EXPLANATION OF SYNF3OLS GeoEngineers Inc. i LOC OF EXPLORATION R /\H•GMD•nn 40 BORING K (CONTINUED) *GRAPHIC *TEST DATA LOG DESCRIPTION FIGURE A -18 45- H w 50 z H a w 55- 60- 65 70- 75- 80- 32 27.7% 95.911 54 27.9% 96.711 31 27.1% 96.411 58 30.1% 93.011 82 25.3% 98.411 76 27.0% 98.01 50 4" 24.5% 101.311 65 20.2% 110.011 i ML ML MANY SLICKENSIDES .VERTICAL COLOR CONTACT IN SILT SLICKENSIDES DISTORTIONS IN SAND LENSE SLICKENSIDES GRADES TO VERY STIFF MANY SLICKENSIDES SLICKENSIDE TRACE OF SOME VERY FINE SANDY WET VERY FINE SANDY SILT LENSES GRAY FINE SANDY SILT (STIFF, WET) `77VBROWN SILTY SANDY GRAVEL (DENSE, WET) *SEE KEY FOR EXPLANATION OF SY*+ROT.S GeoEngineers Inc. i LOG OF EXPLORATION RAN '. (IMD: nn 80 BORING K (CONTINUED) *GRAPHIC *TEST DATA LOG DESCRIPTION FIGURE A -19 70 6" 23.0% 104.011 85— 50 4" 25.9% 98.811 ck: 9 0 r z GP ML GRAY FINE SANDY SILT (STIFF, WET) BORING COMPLETED AT 88 FEET 9 INCHES ON 10/17/83 GROUND WATER LEVELS MEASURED AT 14 FEET AND 79.5 FEET DURING DRILLING PIEZOMETER INSTALLED IN GRAVEL LAYER AT 88 FEET *SEE KEY FOR EXPLANATION OF SYNBfT,S GeoEngineers Inc. LOG OF EXPLORATION • • APPENDIX B INSTRUMEPTPATION AND MONITORING PIEZOMETRIC LEVELS A series of water level measurements was made in the piezometers installed by GeoEngineers, Inc.; in Piezometers 1A, IB, and 1 installed by Shannon & Wilson in 1966; and in the Group 1 vertical wells installed by the Washington State Department of Transportation (WSDOT) during construction of the 1 -5 /I -405 interchange in the mid- 1960s. The water levels measured in the piezometers and wells since November 1983 are presented in Tables B -1 through B -3. The elevation datum used is the Valvue Sewer District datum. INCLINOMETER DATA The inclinometer in Boring F was initialized on November 1, 1983. Subsequent sets of readings were taken on November 18, 1983 and March 12, 1985. The readings indicate no discernible movements at this time. The data are available for review or copying from our files. B - 1 GeoEngineers Incorporated TABLE B -1 PIEZOMETRIC LEVELS - GEOENGINEERS, INC. BORINGS Ground Elevation of Water Table (Feet) Surface Elev. Boring (feet) 11/18/83 11/30/84 3/4/85 3/12/85 C 237.1 196.6 196 197 D 178.8 172.7(1) 172(1)(2) 123 123 G 179.2 163.3(1) 103 102 H 229.5 189.1 184.5 183.5 J(top) 195.4 184.1 184.5 185.5 185.5 J(bottom) 195.4 167.8(1) 114.5 166.5(1) 114.5 K 175.0 129.5 - (3) L 207.5 177.6 177.5 178 NOTES: (1) High water levels possibly due to surface water infiltration. (2) Reading obtained on 12/12/84. (3) Piezometer K plugged at 7 foot depth. B - 2 GeoEngineers Incorporated • TABLE 8-2 PIEZOMETBIC LEVELS - SHANNON & WILSON PIEZOMETEBS Casing Elevation of Water Table Elev. (Feet) Piezometer (feet) 3/4/85 3/12/85 IA 148.5 93.5 93.5 1B 151.5 111.5 111.5 1(1) 165.0 146.5(1) 139 (1) NOTE: (1) Piezometer 1 consists of a slope indicator casing and is obstructed at Elevation 130. B - 3 GeoEngineers Incorporated TABLE B -3 PIEZOMETRIC LEVELS - GROUP 1 WSDOT WELLS Casing Elevation of Water Table (feet) Elev. Well No. (feet) 11/30/84 3/4/85 3/12/85 1 161.4 143.5 144 144 2 162.6 148.5 147 147 3 162.8 152.0 152.5 152.5 4 166.2 - 101 101 5 166.5 103.5 104.5 104.5 6 166.4 - (1) - - 7 163.2 140 140 8 162.1 124 124 9 162.6 109.5 109.5 10 157.5 107.5 107.5 107.5 11 156.8 108 108 108 12 157.3 108.5 108.5 107.5 13 155.0 104 104 14 153.8 111 112 112 15 152.8 113 113 16 147.4 116.5 115.5 17 146.6 116.5 116.5 18 145.4 117.5 116.5 19 136.5 94.5. 94.5 20 135.1 118 118 21a - (2) 21b 133.1 117 117 116 22 131.0 dry at 86' dry at 86' dry at 86' 23 131.3 96.5 97.5 24 130.3 97 96.5 NOTES: (1) Well No. 6 plugged at 9 foot depth. (2) Well No. 21a plugged at 10 foot depth. B - 4 GeoEngineers Incorporated TABLE B-4 GROUP 1 WSDOT VERTICAL WELL /HORIZONTAL DRAIN SYSTEM Well Ground GEI WSDOT Surface Pump Elevation Outlet Well Well No. Elevation Elevation at Well Elevation Grade Length No Series No. Feet Feet Feet Feet % Feet 1 I 1 159.6 60.1 80.9 80.5 2 213.0 2 2 160.1 61.0 82.6 80.5 1 222.6 3 3 160.5 56.0 81.6 80.5 2 223.1 4 II 1 164.6 54.5 82.1 81.7 2 233.6 5 2 164.3 51.8 82.8 82.8 2 223.4 6 3 164.1 51.6 86.9 82.6 2 223.6 7 III 1 162.3 53.4 83.4 83.3 2 223.7 8 2 161.5 51.3 88.0 83.9 2 212.8 9 3 161.0 52.7 86.5 84.4 1 213.7 10 IV 1 156.7 50.6 .84.5 84.9 0 204.9 11 2 155.4 53.0 87.3 85.0 1 203.3 12 3 156.5 51.4 90.1 86.2 2 214.8 13 V 1 153.3 50.2 87.8 87.4 1 183.8 14 2 152.4 54.2 89.7 88.0 1 184.3 15 3 151.2 N/S 90.1 88.4 1 184.7 16 VI 1 145.7 42.5. 90.6 89.8 2 152.8 17 2 . 144.7 N/S 92.0 90.6 1 153.2 18 3 143.8 62.8 92.4 91.0 1 152.9 19 VII 1 133.5 N/S 93.7 93.0 1 134.8 20 2 132.9 N/S 95.8 94.5 1 135.1 21 3 132.2 N/S 94.6 94.6 0 126.6 22 VIII 1 128.2 N/S 97.1 97.1 0 95.0 23 2 128.9 N/S 97.5 97.5 0 84.8 24 3 128.6 N/S 97.9 97.9 0 85.5 Horizontal Drain Parameters N/S Not shown on WSDOT documents. B- 5 GeoEngineers Incorporated • • APPENDIX C SLOPE STABILITY ANALYSES INTRODUCTION A description of the slope stability analyses for the deep- seated sliding failure mode and the results are presented in this appendix. Methodology: Deep- seated block -type sliding was analyzed with the aid of the computer program STABL, which allows analyses of shear surfaces of general shapes, including sliding blocks. The program is based on Carter's Method. Critical failure surfaces are generated using pseudo random techni- ques. The input parameters include slope topography, piezometric levels in the lower sand aquifer, soil strengths, earthquake acceleration coefficients and building loads on the slope. The initial phase of our analyses included back-calculating soil strengths from conditions existing during sliding in 1961. The back- calculated soil strengths were obtained by changing the input values to achieve a computed factor of safety of about 1.0. These strengths, along with water level and topographic information were used to compute a new factor of safety for conditions existing in March 1985. The effects of water level rise, earthquake loading, and building loads on the factor of safety were then evaluated. Assumptions: Several assumptions were necessary in evaluating deep - seated block sliding stability. Topography representative of conditions existing in 1961 (soon after the major slide of 1960) and those existing at present (1985) were evaluated. Topographic conditions assumed in 1961 were based on Plate 3 of the Dames & Moore report dated June 27, 1961. Topographic conditions existing at present (1985) are based on topographic information provided by Stepan & Associates, Inc. for . the section of the slope located between the uphill and downhill property lines. Topography below the downhill property line and above the uphill property line was estimated from Figure 1 in the Shannon & Wilson report dated June 21, 1968. The sections judged most critical of those used in our analyses are shown on Figures C -1 and C -2 for the 1961 and 1985 topographies, respectively. C- 1 GeoEngineers Incorporated • • The location of the section depicted on Figure C -1 and C -2 is shown on Figure 1. The location of the section used in the 1961 Dames & Moore report differs from that used in our analyses and is located to the southeast of the section we have used. The section shown on Figure C -2 is drawn through the center of a large swale, while the borings drilled both for our studies and by Dames & Moore are located on the flanks of this swale. The differences in topographic conditions shown in 1961 and 1985 indicates that a significant amount of material is absent from the lower portion of the slide area, particularly below the downhill property line. The difference could be attributable to material removal as well as to the different sections used by Dames & Moore and GeoEngineers. Soil conditions depicted in all of the borings used to develop our cross sections vary significantly. This is especially true of Borings DM -1 and D, DM -3 and G, and DM -4 and C. Variations across the swale are also apparent when comparing the logs for Borings DM -1 and DM -3 with D and G, respectively. The presence and variable elevations of sand lenses throughout the thick fine - grained layer (Unit 8) probably account for the major part of this variability. They also have a significant influence on the location of the failure surface. The location of failure zones identified from slope indicator measurements in the Dames & Moore borings and zones of slickensided material encountered in Borings C, D, G, L and F were used to estimate the probable location of the slide plane in our analyses. See Figure 1. For both topographic conditions (1961 and 1985), the soil conditions were simplified to a three -layer system. The uppermost layer includes the surficial silty sand and thick fine - grained soil units (Units A and B shown in Figure 1). The second layer (underlying the thick fine - grained soil unit) was assumed as a thin (5- foot - thick) zone of weak material through which the slide plane passes. Material underlying this weak layer was assigned a higher strength and represents dense glacially compacted soils through which the slide plane probably does not pass. The extent of the weak zone was estimated from our borings and the Dames & Moore borings. C — 2' GeoEngineers Incorporated • • Water levels for the 1961 analysis had to be estimated as artesian conditions existed at the time the borings were drilled by Dames & Moore in 1961. Based on the observations by Dames & Moore personnel of the rate of flow from the borings, the piezometric surface was assumed at 5 feet above the existing ground surface. Water level information from our borings and Shannon & Wilson Piezometers 1, IA and 1B were used to establish the piezometric surface existing in 1985. The sliding block failure surface was modeled using five constraint areas positioned along the lower boundary of the assumed weak zone. The downhill exit point for the slide was based on the exit point indicated in the 1961 Dames & Moore report. This exit point may have been observed at that time because this portion of the site was cleared as a result of borrow operations. The failure surfaces are shown in Figures C -1 and C -2 for 1961 and 1985, respectively. Selection of Parameters: The analyses using 1961 conditions were performed by varying soil strengths of the upper two soil layers until a factor of safety of approximately 1.0 was obtained. The friction angles for this condition were computed at 25 degrees for the upper material and 15 degrees for the weak zone material. These friction angles are considered to be residual values and the cohesion intercepts were accordingly assumed to be zero. The analyses indicate a zone of critical failure surfaces having nearly equal factors of safety near the uphill property line. See Figure C -1. Results: T.he failure surface and piezometric conditions evaluated for existing conditions are shown in Figure C -2. The analyses indicate a factor of safety of 1.5 to 1.6 for the section assumed in the analysis. Our analyses of the stability of sections located outside of the swale yield factors of safety approximately the same for existing piezometric conditions. Additional Analyses: We then evaluated the effects of an increase in the water level. Factors of safety of 1.3 and 1.0 were obtained when the piezometric levels were raised 10- and 20 -feet, respectively, above existing levels. C - 3 GeoEnglneers Incorporated • • We also evaluated the effect of the building loads on deep- seated stability by assuming an average areal building load of 200 pounds per square foot extending over the building footprints at two locations on the slope. The factor of safety obtained for this loading condition was nearly identical with that obtained without building loads. Dynamic Analysis: Dynamic stability was evaluated by subjecting the slope to a horizontal acceleration coefficient of 0.15 with the piezometric surface at current levels. We assigned a cohesion value of 500 psf and a friction angle of 15 degrees to the weak zone to represent undrained soil strength. This is considered to be conservative and to be more appropriate for earthquake loading. A factor of safety of 1.13 was obtained for these conditions. While the factor of safety indicated for dynamic loading conditions is relatively low, this value is considered, in general practice, to provide a level of risk comparable to a factor of safety of 1.5 for static conditions. Strains and, therefore, slope movement developed during earthquake loading will probably be limited. This is normally observed in cohesive soils during earthquake loading and is indicated by the reported localized zones of cracking in the uphill portion of the slide area during the 1965 Seattle earthquake. c - GeoEngineers Incorporated FIGURE C -I 360- 370- 280 - 2%0-* 700 - 0 160 If 170- 80 4U- 0 (0,100) (0,82) (120,88) (96,116) (243,162) PROPERTY LINE 1 96 1 Topography ESTIMATED PIE20METRIC LEVEL (364,173) - - (337,164) PROPERTY LINE SLADE MAY ZONE OF GENERATED SURFACES CRITICAL FAILURE (728 252) (786,253) (880,275) L = 125 PCF SOIL 0 C = 0 Sg -240 - -,° - ?(880,228 • - 360 -320 - 280 (526,190) (526,171) (0,64) (364,133) 51101144 BLUE. 1AILURI SURIALL (526,166) (880,209) (880,204) SOIL O 3 = 120 PCF C = 0 0 = 15' SOIL 0 ( = 130 PCF C = 0 0 = 15' 1 1 1 1 1 1 1 1 1 '760 800 840 880 0 40 80 120 160 200 240 280 320 360 400 440 480 520 560 600 640 680 720 DISTANCE IN FEET 141)115: 1) 51C11ON LINE IS SECTION A -A. SIIOMN IN FIGURE 1. 2) TOPOGRAPHY BASED ON PLATE 3 IN DAMES L MOORE REPORT DATED 6/77/61 AND CORRESPONDS 10 CONDITIONS 60151 - IN1: AI1tO SLIDE Of 1960 -61. 1) 11A1IR LEVELS ESTIMATED 680M BORINGS DRILLED BY DAMES L MOORS IN 1961. 200 4. z z 0 160 i 120. 80 -40 GeoEngineers Inc. CROSS SECTION FOR STABILITY ANALY,IS • APPENDIX B UTILITIES REPORT FIGURE C -2 360 ^ 320 - 280 240- r 200^ z ELEVATION 160^ PROPERTY LINE 1985 Topography ESTIMATED PIEZOMETRIC SURFACE (457,171) (542,200 ZONE OF GENERATED CRITICAL FAILURE SURFACES PROPERTY LINE (72 SLADE WAY ,252) (786,253) (880,275) (302,141) 120- 80 (0,69) 40 0 (364,133) 0 0,100) 0,76)) (0,64) (242,115) (120,88) S110161. BLOC• IAILURt SURFACE (526,171) (526,166) SOIL (J ! = 120 PCF C = 0 O= IS SOIL p3 ! = 130 PCF C = 0 0 = 35 - 360 320 280 -24.0 880,228) 880,204) 200 (880,204) z -160 0 i - 1201 -60 - 40 1 80, 1 1 1 1 1 I 1 1 L 1 I I T 160 200 240 280 320 560 400 1.1.0 480 520 560 600 DISIANCE IN FEE1 120 NOTES:. 1) SECTION LINE 15 SECTION A -A' SHOWN IN FIGURE 1. 2) TOPOGRAPHY BELOW DOWNHILL PROPERTY LINE AND ABOVE UPHILL PROPERTY LINE BASED ON FIGURE I IN SHANNON 6 WILSON REPORT GATED 6/21/68. 1) TOPOGRAPHY BETWEEN PROPERTY LINES BASED ON PRE- LIMINARY TOPOGRAPHIC MAP PROVIDED BY SIEPAN ASSOCIATES, INC., DATED MARCH, 1985. 4) WATER LEVELS BASED ON MEASUREMENTS MARL IN PIEZOMETERS IN51A1L(D BY GE0ENGIN(ER5 AND SHANNON L WILSON, AND IN GROUP 1 VERTICAL DRAINAGE WELLS INSTALLED BY W5Ll0I , 1 1 1 680 640 1 1 1 1 720 760 1100 640 0 880 GeoEngineers Inc. ICRUST, SE(:1 ION FOR SJAI3I L I T Y ANAL Y'I I S • • / /if �1i / v A EXISTING STORM SYSTEM & EASEMENT ����NY►N� \N� EXISTING STORM a9• Iwo S gip !M CONTROL MN EXISTING SEWER & EASEMENsT / J °�` \�o VALLEY VIEW ESTATES SITE UTILITY PLAN l(-5�'� FIGURE 16 LEGEND simmisePROPOSED STORM LINE \ \\ \PROPOSED WATER LINE ■U■ ■PROPOSED SANITARY SEWER Lir.. • VALLEY VIEW ESTATES UTILITY. REPORT Prepared By: STEPAN & ASSOCIATES, INC. 930 SOUTH 336TH STREET FEDERAL. WAY, WASHINGTON 98003 5 -1 -85 STORMWATER RUNOFF /ABSORPTION EXISTING CONDITIONS The site slopes generally from west to east with a drainage swale bisect- ing the southern portion of the site. Slopes vary from 3% to 50%. Site vege- tation consists of alder, a few maple and dense blackberry vines. As stated in the surface water portion of the geotechnical report pre- pared by Geo Engineers, permeability is relatively low in Units A and B (ref. Figure 4 in the geotechnical report) and significantly higher in Unit C. The Washington State Department of Transportation has installed a series of large diameter wells and horizontal drains just east of the site to modify and control the water table (Ref. Figure 1 in the geotechnical report). This sys- tem was installed during the construction of Interstate 5. This will be referred to as the WSDOT system in the remainder of this report. Impacts: Existing surface runoff and absorption characteristics would be altered by aspects of the proposed development: the installation of drainage systems, removal of vegetation during site preparation, fill and grading, and introduction of impervious surfaces on the site in the form of roads, parking areas, and structures. Off -site features such as the City of Seattle water line should not be effected by the proposed development. Absorption would be reduced, and the volume of runoff would, be increased as described below. Mitigating Measures: The proposed stormwater facilities as shown on the attached Site Utility Plan and sub - surface facilities as described in the geotechnical report prepared by GeoEngineers would mitigate the impacts of site development on runoff and absorption characteristics. The engineering drawings for the storm water system will be prepared in accordance with City of Tukwila requirements and are subject to City review and approval. SURFACE WATER MOVEMENT AND QUANTITY Existing Conditions: The site drainage basin is bounded by Slade Way and the extension of 158th Street on the north. The basin area is 7.2 acres and is divided into 2 sub basins the south being 4.4 acres and the north 2.8 acres. Drainage from the site flows directly to the Green River through a series of,pipes and open channels which are described below. Surface runoff from the southern portion of the site (4.4 acres) sheet flows to a rip -rap lined ditch which bisects the south side of the site. This ditch flows to a receiving structure on the south side of Klickitat Drive. A 24 -inch pipe runs from the receiving structure to a manhole where the pipe size increases to 30" under Klickitat Drive. This 30 -inch line then runs para- llel to Klickitat and connects to a 48" line which runs parallel to the north- bound lane of Interstate 5. The 48 -inch line then crosses under Interstate 5 and discharges in a lined open channel which is on the west and north side of Southcenter Parkway. The channel flows through a short section of 78 -inch pipe and a section of 108 -inch pipe and then discharges in the Green River. • • Surface runoff from the north portion of the site (2.8 acres) sheet flows to a lined ditch along the east side of the site. The ditch flows to a receiv- ing structure near the northeast corner of the site. An 18 -inch pipe runs from the structure to a manhole where the pipe size increases to 24 ". This line runs under Interstate 5 and ties into the same 48 -inch line which was described in the preceding paragraph. The flows follow the same route to the Green River as described for the southern portion of the site. The WSDOT system of vertical wells are connected to horizontal drains which also flow to the systems described above. Off -site flow from approximately 12 acres of mostly single - family resi- dences west of Slade Way and south of South 160th Street enters the site south of the intersection to South 160th Street and 53rd Avenue South. Part of this system parallel to 53rd Road South runs above ground, and is leaking (observa- tion 10/17/83), causing some ponding in the immediate area. The system also consists of 12 -inch and 18 -inch underground pipe and runs generally in a north - south direction. This pipe connects to the same 24 -inch line described in the paragraph above. From here the runoff travels the same path to the Green River as that previously described. Impacts: Construction of the proposed development would not alter existing drainage basin boundaries. Site development would eliminate existing natural surface flow and infiltration characteristics and introduce an addi- tional buried conduit system. The new drainage collection system would con- tain and direct surface water at higher velocities and in different directions across the site, as shown on the Site Utility Plan; however, stormwater would continue to exit the property at the same points along the southern an eastern boundary. Changes in potential peak flow of storm runoff due to building construc- tion and paving will be controlled by the drainage retention and runoff con- trol system. Surface water would be collected in a subsurface conduit system as shown on the site utility plan, which would direct stormwater drainage at higher velocities and in slightly different directions across the site. The new storm sytem would also collect existing on -site horizontal drains (ref. Figure 3 - GeoEngineers Report and footing and retaining wall drains. The proposed drainage system includes storm drainage retention pipes and control structures which would control and store storm water to limit the runoff rate to a predevelopment rate. Therefore, surface water would exit the site at approximately the same rate as it does under existing conditions. The installation of a storm drain system would provide positive benefits because it would collect and channel surface water, some of which is currently flowing in ill- defined channels, and direct it to a controlled system outflow. The storm drain system and the system of foundation wall drains will also increase the factor of safety against sliding in the upper layers of soil (Ref. page 15 geotechnical report) and provide less impact on the WSDOT System (Ref. page 23). The 7.2 acre drainage basin is divided into 2 sub basins the south being 4.4 acres and the north 2.8 acres. Based on a storm of 10 year recurrence interval, the south basin would require approximately 1,500 cu. ft. of storage capacity, and the north basin would require approximately 1,000 cu. ft. of storage. The size of the controlled outlet from the site would be runoff at a rate that would not exceed existing conditions. -2- • • Since runoff from the site flows directly to the Green River as detailed in the preceding paragraphs, an alternate to this would be to provide no deten- tion for the site. This is a normal practice on sites which flow directly to a large body of water or river. There would be several benefits from this. The principal benefit would be elimination of a possible source of water leakage from the detention struc- ture. It would also eliminate some of the excavation and disturbance of the hillside on -site. As shown on the attached storm calculation sheet the introduction of impervious surfaces would increase the peak surface runoff from a total of 1.36 cubic feet per second (CFS) to approximately 3.34 CFS during 10 -year storm conditions. This is an increase of 1.98 CFS at the peak. Surface run- off would increase a total of 1.67 CFS to 4.13 CFS during a 25 -year storm. This is an increase of 2.46 CFS at the peak runoff. This is a relatively small increase given the size and capacity of the downstream storm system which is capable of handling 20 CFS or greater. Mitigating Measures: A stormwater system designed in accordance with City of Tukwila requirements and requirements and recommendations detailed in the geotechnical report prepared by Geo Engineers is proposed to be installed. The City of Tukwila must approve stormwater drainage plans prior to issuance of the building permit. The site development sequence and facilities as recommended in the geotechnical report prepared by GeoEngineers would be included on the detailed site grading plan. A temporary storm management system and the erosion control measures as described in the geotechnical report will be employed during construction. Where possible, natural vegetation for silt control will be maintained. Temporary siltation ponds shall be constructed by placing straw bales across swales. All temporary and erosion control measures will be maintained in a satisfactory condition until such time as cleaning and /or construction is completed and permanent drainage facilities are operational. The temporary siltation ponds should not effect the groundwater table. The proponent would have maintenance responsibility for the drainage control facilities during construction, and it is proposed that the owner assumes maintenance responsibility for these on -site facilities after comple- tion of the development. Cleaning, flushing and regular maintenance of the WSDOT drain systems described in the geotechnical report is essential. A portion of the existing storm system would be abandoned (See Appendix - Letter from Department of Transportation) and replaced by a new storm line to handle off -site runoff as shown on the site utility plan. The existing storm line that is above ground and leaking would be repaired. Surface Water Quality Existing Conditions: There is no known water quality data for surface runoff from the site. -3- • • Impacts: The introduction of impervious surfaces over a portion of the proposeddevelopment would reduce the area of exposed soils. Therefore, reduced quantities of sediment, nutrients, and organic material contained in the soil would be expected to leave the site in surface runoff. However, in place of these would be contaminants more typical of residential developments: petroleum residues, traces of heavy metals, and sediments washed from roads and driveways. The increased quantity of impervious surfaces would increase the volume of stormwater runoff from the site. Catch basins and oil /water separators proposed within the on -site drainage collection system would func- tion to separate sediments and petroleum residues from stormwater to a certain extent. On -site drainage detention and the outlet control structure would further allow for separation of these pollutants from storm water before release from the site. Use of pesticides, herbicides, and fertilizers (if any) on yards and on landscaping in common areas may occasionally contribute slight quantities of contaminants to stormwater that would not be removed by the proposed pollution separation devices. Also, the partial coverage of soils with asphalt paving and structures may result in slight elevation of temperature of runoff from these surfaces. Perhaps the greatest significant potential for adverse impact on surface water quality would be during temporary construction periods. Clearing and grading would expose soils on the site to potential erosion by rainfall. Mitigating Measures: The proponent would have maintenance responsibility for the on -site drainage control facilities. Cleaning, flushing and regular maintenace of the existng WSDOT systems as described in the geotechnical report is essential. Catch basins and oil /water separators should be cleaned frequently and properly maintained to assure maximum attainable pollution separation. SANITARY SEWER SYSTEM Existing Condition: The site would be served by Val Vue Sewer District. There is an existing 12 -inch cast iron sewage main which runs through the site as shown on the utility site plan. The line connects to Metro at the Hat Highlands connection. Sewage from the site would be treated at the Renton Sewage Treatment Plant and would be transmitted to the plant via the freeway interceptor, Val Vue outfall and Tukwila interceptor. The proposed project is within Metro's Renton treatment plant service area. Metro has prepared a facilities plan for the Renton system with a grant from DOE and EPA, in part because the Renton treatment plant has reached its "design" capacity and continued development is occurring within the service area. A final plan for the Renton service area was adopted by the Metro Council in November, 1981 and contains a recommended program for upgrading the Renton system so that water quality and health will continue to be protectect- ed. The plan was amended on April 5, 1984 to revise the alignment for the effluent transfer system pipeline. These improvements will be on line in early 1987. Impact: The on -site sewage collection system would be designed by the proponent s engineer and would be installed as shown on the site utility plan. Six- and eight -inch lines would collect sewage throughout the project and con- nect into the existing Val Vue sewer line as shown. A field survey of this area has recently been completed which indicates the existing sanitary sewer would be relocated so that it will not be under the proposed buildings. This is indicated on the site utilty plan. As per the attached letter from Val Vue Sewer District the relocation construction of this line can occur without any disruption of service in the existing line. The development will result in increased sewage flows. As stated above, the Renton Treatment Plant is currently treating more than design capacity but temporary measures are being taken which will accommodate flows. The plant will be upgraded by early 1987.if present plans are implemented. Mitigating Measures: If water use was reduced by residents implementing water - saving measures in their homes, the volume of sewage that would be discharged from the project area would also be reduced. SOLID WASTE Existing Conditions: The business and residences in the surrounding vicinity are currently served by Sea -Tac Disposal. Dumpsters and compactors can be rented from them. The solid waste is taken to the King County Transfer Station. Impacts: The proposed development will increase demand for solid waste collection which can adequately be provided by Sea -Tac. Disposal. Mitigating Measures: None WATER SYSTEM Existing Conditions: The project is located in Water District No. 75 service area and would be served from the District's supply and distribution system (ref. letters to and from Water District No. 75, attached). The District is supplied from the large Cedar River Pipeline which runs adjacent to the site. The District anticipates that this source will be able to meet long -range demands for water in this area. (Conversation with Duane Huskey on 3/26/85). The District has a 6 -inch main that extends to the intersection of South 160th Street and 53rd Avenue South. There is also an 8 -inch main that extends east on South 166th Street and terminates approximately 200 feet west of the intersection with 54th Avenue South. Static pressure in this area is 125 psi. Impacts: The District's water distribution would be extended from the 6 -inc mh ain in South 160th Street with a new 8" main on Slade Way. This would be as called for in the District's Comprehensive Plan. Connections from this main would supply the proposed development with water. Fire hydrants will be spaced as required to provide adequate fire protection. The water system would be designed by the proponent's engineer. This existing system could . supply adequate fire and potable water flow to the proposed development. (Conversation with Duane Huskey on 3/25/85). The system within the development would be maintained by the owners. The system within the Slade Way right -of -way would be maintained by Water District No. 75. Installation of the water system to serve the proposed development could have short -term impacts on vehicular travel on Slade Way where trenching is . required within the right -of -way or across the road. During actual connec -• tion of the project system to the District system, water service in the area could be interrupted for brief periods of time. Implementation of the proposal would result in a long -term commitment of the District water supply to serve the proposed development; however, as stated above, the District does not expect to experience difficulty in meeting long -range demands in the area. The proposed on -site system would comply with City of Tukwila fire flow and hydrant- spacing requirements, as well as with the requirements of the Washington State Department of Social and Health Services. The on -site system would comply with Water District No. 75 installation requirements including those to prevent a cross - connection between water and sewer. According to Washington Survey and Rating Bureau criteria, approximately 2100 gpm (see appendix for calculations) is the required fire flow for multi - family develop- ments of this type. The proposed system would meet the minimum criteria. Projected domestic water usage for the site should not exceed 0.04 mgd on a peak day (see appendix for calculations). Mitigating Measures: Installation of water- saving fixtures and devices such as flow restrictors in new dwelling. units (at the discretion of the builder) could reduce water consumption, but the feasibility and necessity of this is doubtful. -6- ... • _- _ i .' / EXISTING STORM SYSTEM & EASEMENT I ; e, 0/ /, 0/ 0/ . 0 k. • �I .18 • • 0/. / O) EXISTING STORM INTERCEPTOR TRENCH (- -- — • L CIO 41044N 41AtiA ` , X10 �v k ( /Lc° CONTROL MH \O"' 1•• DETENTIi PIPE EXISTING SEWER & EASEMENh VALLEY VIEW ESTATES SITE UTILITY PLAN 8� • • • PROPOSED Amw■mm. PROPOSED — molpPROPOSED ■■•\' PROPOSED ■••■ PROPOSED LEGEND • • FRENCH DRAIN INTERCEPTOR TRENCI- STORM LINE WATER LINE SANITARY CFWFR 1 IN APPENDIX VALLEY VIEW ESTATES Preliminary Storm Drainage Analysis Storm Drainage Criteria The storm drainage system for the proposed project as previously described shall be based upon the following criteria.. These criteria and method of analysis are quoted from the "Requirements and Guidelines for Storm Drainage Control in King County ", Division of Hydraulics, King County, May 1979 and that document should be referenced for additional information. 1. Runoff Rate Q = CIA where 0 = Rate of flow in cubic feet /second C = Runoff co- efficient based on relative imperviousness of the area i = Rainfall intensity in inches /hour for Seattle area A = Area of runoff in acres 2. Calculation of drainage pipes, ditches and other facilities will be completed, based on requirements with design of the final facilities. Southn Basin Area in basin = 4.4 acres Travel length = 500 feet Velocity (slope average 25 %) = 1.3 FPS (bare ground) Travel Time = 10 + 500 = 16.4 minutes 1.3(60) i = 1.25. inch /min. 1tSeattle) i25 = 1.55 inch /min. "c" existing = .15 Existing 10 -year peak rate = 0 existing = CiA = (.15)(1.25)(4.4) = 0.83 cfs Existing 25 -year peak rate = 0 existing = 0.15 (1.55)(4.4) = 1.02 cfs CFuture = 2.1 ac (0.90) + 5.0 ac (.15) = 0.37 .1 Future 10 -year peak = (.37)(1.25)(4.4) = 2.04 cfs Future 25 -year peak = (.37)(1.55)(4.0) = 2.52 cfs • • Qo = 0existing. Area ( future) 0.83 = 0.51 4.4(0.37) T = -25 + 1763 = 34 minutes 0.51 VS 2. = 2P20(34 - 40(0.51) 34 = 931 ft.3r,cre (.c. future) VT = 931 (4.4)(.37) = 1516 ft.3 detention volume North Basin Area in basin - 2.8 acres Travel length = 500 feet Velocity = 1.3 fps Travel Time = 10 + 500 = 16.4 minutes 1.3(60) 110 = 1.25 inch /min. 125 = 1.55 "c "existing = .15 Existing 25 -year peak = 0.15 (1.55)(2.8) .= 0.65 cfs Existing 10 -year peak rate = Qexisting = CiA = (0.15)(1.25)(2.8) = 0.53 cfs future = 2.1(0.9) + 5(1.5) = 0.37 7.1 Future 10 -year peak = .37 (1.25)(2.8) =. 1.30 cfs Future 25 -year peak = .37 (1.55)(2.8) = 1.61 cfs Qo = °existing = .53 = 0.51 • Area ( "c" future) 2.8 .37 T = -25 + 1762 = 34 minutes 0-. Vs = 2820(34) - 40(0.51)34 = 931 ft.3 /Acre ( "c "existing) 25 + 34 VT = 431(2.8).37 = 965 ft.3 detention volume Fire Flow .keclui rements F= 18 C(A)°.5 * C= 1.5 Wood Frame Construction A= 5,248 Square Feet F= 18 (1.5(5248)0'5 = 1,956 ypn use Less 25% (low hazard occupancy) Plus Exposures (20% + 20 %) =40% = 2,000 gpm -500 1,500 +600 2,100 gpn Projected Water Usage Multi Family - 90 gal /unit -day Peaking Factor = 18 + p P- poulation 4 + P = 18 + 0.216 = 4.14 + 0.216 in thousands Flow = 90 gal /unity -day x 108 units x 4.14 1,000,000 gal /mg = 0.04 million gallons per day * Guide for determination of required fire flow; Insurance Service Oftice Sanitary Sewer Flow Multi - Family 90 gal /unit -day. Infiltration Inflow = 1,100 gal /ac -day; 7.2 acres Peaking factor = 18 + P = 4.14 Flow = 90x108x4.14 + 1,100 x7.2 = 0.05 million gallons per day 1,000,000 7 I. STEPAN & ASSOCIATES, Inc. April 16, 1985 Mr. Richard Johnson Design Engineer Dept. of Transportation State of Washington 9611 S.E. 36th Street Mercer Island, WA 98040 Reference: Valley View Estates E.I.S. Dear Richard: After discussions with the soils consultant, GeoEngineers, we would like to request on behalf of Puget Western, Inc. the following: 1) The horizontal drains be flushed and cleaned. Also do the horizontal drains consist of 10' of stainless steel screen and the remainder tight - line to the vertical wells? The horizontal drainage and /or vertical wells appear to be plugged since the water level in the wells is at a higher level than where the horizontal drains intersect the vertical wells. 2) The vertical wells be flushed and cleaned. Also bolt in place and lock the covered plates on the wells. 3) What is the status and condition of the pumps that are currently in the wells. What is the status of the condition and location of those that have been removed from the wells? 4) A repair and flushing of the original test drains shown on the attached sketch. Also any documents as to where these drains connect to. If you have any questions, please contact Jack Tuttle or Gordon Denby at 881 -7900 or myself at 682 -4771. Very truly yours, STEP N A ASpCIATES, INC. Glenn McKinney, P.E. Vice President GM /gc cc: Joel Haggard, Attorney Tom Russell, Puget Western Jack Tuttle, GeoEngineers • 930 South 336th StrFet, Suite A • frderal Way. Washington 9800 i • T acoma 927.7A50. Seattle M2.4771 • F1t;URE 2 • 3A- 119 Co ;Me sou (R')t r ■ ■N. Project Sit.. • Approximate Extent of Slide 4- 20- 611.. r - 0 100 200 300 Scale In Feet Reference: Drawing entitled "Plan of Completed Remedial Measures" by Shannon 6 Wilson dated March 31, 1966. Legend: Horizontal Drains (existing) o °° --Original Test Drains 0------Recommended Drain (Grade: 1 -32) 'Cylinder Pile Wall 41immmailmExisting or Proposed Right of Way ♦ Additional Vertical Drains (6 -9 in. dia.) • Large Diameter (5') Deep Well 4:1 Final Excavated Slope (horizontal:vertical) • Piezometer Installed During 1966 Investigation GeoEngineers Inc. 11 R \11 IV1. STEPAN & ASSOCIATES, Inc. April 17, 1985 Mr. Duane Huskey, P.E. Water District No. 75 P.O. Box 68100 Riverton Heights Station Seattle, WA 98168 Reference: Valley View Estates Water Service Dear Dwain: As per your letter of April 10, 1985, an 8 -inch main, not a 6 -inch main, would be installed in Slade Way. Also attached for your review is a rough draft of the water portion of the Valley View E.I.S. Please call me if you have any questions or comments. Very truly yours, STEPAN & ASSOCIATES, INC. Glenn McKinney, P.E. Vice President GM /gc Attachment. • ' i0 Smith 3 3hth Street. Suite A • Federdl b4 .��,' '. hint;l�m 481h14 • I.tcoma '12' 71110 . Seattle (,M2 .1-71 • I& tNGINIERING i STEPAN & ASSOCIATES, Inc. March 25, 1985 Mr. Duane Huskey, P.E. Water District No. 75 P.O. Box 68100 Riverton Heights Station Seattle, WA 98168 Reference: Water Service for Proposed Valley View Project / Slade Way Dear Duane: As per our discussion, a new 6" main from your existing 6" line in South 160th Street to your existing 8" main in South 166th Street would provide adequate fire (2100 gpm) and domestic flow. Water District No. 75 would pay for the portion of the new main in 54th Avenue. If you have any questions, please contact me.. Very truly yours, STEPAN & ASS 9,�IATES, INC. Glenn McKinney, P.E. Vice President GM /gc cc: T. Russell J. Haggard • 930 South 336th Street, Suite A • Federal Way, Washington 98003 • l aroma. 927.7M0 Seattle. 682.4771 • DAN N "T.ALDVIELL. R•es..-!ent GEORGE _ c_Jh96ERu �ec;e•• JERRY P. HARRIS. Commissioner ?'Valer f i/r c[ f o. April 10, 1985 • /1.119 t oun Ii SEATTLE. WASHINGTON 98168 Stepan & Associates, Inc. 930 South 336th Street Suite A Federal Way, Washington 98003 Attention: Mr. Glenn McKinney, P.E. Vice President Dear Glenn: There seems to be some misunderstanding of the information, either the way I told it to you or the way you heard it, on the new main for the Valley View project on Slade Way. The calculations that we performed showed that by extending a new 8" line from our existing 6" line on South 160th Street, the 2,100 gpm domestic fire flow could be met. The portion of the main along 54th Avenue South is not scheduled for construction at this time but would be connected to the main installed for this project. Please call me if you have any questions. Sincerely, Duane Huskey, /P.E. DH:tmw cc: Ken Hall, Manager, WD #75 KEN HALL KENT HAYDEN DUANE HUSKEY :rg CLIFF BARTLETT Supt-rin :ence •It i • s . 11 WAR. •DI,ICr NO. 7s 19883 28th Ave. South Seattle. Washington 98188 Bus: 824.0373 S re-P/1-A/ caL ,4SS c c. A-Tg 3(. rtvc?/ft c %4y / ("1.4. S'‘fuo3 WE ARE SENDING YOU 2-ittached ❑ Under separate cover via ❑ Shop drawings ❑ Copy of letter O Prints ❑ Change order LIADa cFTa6usuorua. OAT( Z - f - 61's _ JO• NO ION CL6-./4I /Sic if / AfA/ C / A[. Z4,14 7W 4,A/E L4% c ; �0.vs C.. 44 c Ey ✓, Et-) Es74-77 1 ❑ Plans ❑ Samples the following items: ❑ Specifications COPIES DATE NO. DESCRIPTION THESE ARE TRANSMITTED as checked below: O For approval Di-for your use gels requested ❑ For review and comment ❑ Legal description ❑ Approved bills O FOR BIDS DUE ❑ Approved as submitted ❑ Approved as noted ❑ Retumed for corrections ❑ Tracings ❑ Quotation 19 ❑ Resubmit ❑ Submit ❑ Return ❑ Signature ❑ Payment copies for approval copies for distribution corrected prints 0 PRINTS RETURNED AFTER LOAN TO US REMARKS COPY TO SIGNED: 1 DAN N CA n'. ":'E_L P.cci,-+er, GEORGE ocRG JERRY P. HARRIS, Commissio;, • KEN HALL KENT HAYDEN DUANE HUSKEY CLIFF BARTLETT ?l'zI'r liiiricf o. -7ri. n q (nunfi1 SEATTLE. WASHINGTON 98168 January 11, 1985 Stepan & Associates 930 South 336th Street Federal Way, Washington 98003 JAN 141 Attention: Mr. Glenn McKinney Re: Water District No. 75 Comp Plan 1981 -1985 Dear Mr. McKinney: Please find enclosed a copy of Page 102 of Water District No. 75's current Comprehensive Plan. We show extending 3,800 lineal feet of 8" ductile iron main along Slade Way. This would loop our facilities at 51st Avenue South and South 166th Street. Our existing 6" C.I. along South 160th Street could possibly be used depending on fire flow requirements for this development. Hopefully, this information is what you required. Please call me should you have any questions. Sincerely, Duane Huskey, P.E. DH:tmw Enclosure cc: Ken Hall, Manager, WD #75 — TIMETABLE OF IMPROVEMENTS A. The order of listing below is a tentative priority listing subject to change, based on a continuing evaluation of needs. B. The costs shown are estimated at 1981 prices. For each subsequent year prior to construction, an estimated 102 must be added to this cost due to inflation. It is thus recommended that an annual in- crease of 102 be made to the Replacement and Renewal Fiend, in order to keep pace with increased construction costs. ALONG TABLE 23 Replacements and Renewals - Immediate (1981 -1985) $380,000 /Year FROM EST. 1981 TO LENGTH SIZE COST *S. 166th S. 170th *S. 170th S. 170th *S. 175th *S. 192nd S. 208th *S. 236th Slade Way 6th Ave. *33rd Ave. 42nd Ave. *42nd Ave. 42nd Ave. *46th Ave. *53rd Ave. Military *Bow Lake St. St. St. St. St. St. St. St. S. S. S. S. S. S. S. Rd. S. Tank Area *1981 Projects 32nd Ave. S. 40th Ave. S. 49th Ave. S. 51st Ave. S. 33rd Ave. S. Des Moines Way Pac. Hwy. S. 10th Ave. S. 51st Ave. S. Cul -de -Sac S. 170th St. S. 160th St. S. 272nd St. S. 276th St. Star Lake Rd. S. 168th St. S. 224th St. Kent -Des Moines Rd. Fressure Zone Modification 34th Ave. S. 49th Ave. S. Slst Ave. S. 53rd Ave. S. 34th Ave. S. 16th Ave. S. Military Rd. S. 13th P1. S. 54th Ave. S. S. 200th St. S. 175th St. S. 164th St. S. 276th St. S. 280th St. S. 280th St. S. 170th St. • • 1100' 8" $ 24,200 2,700' 8" 59,400 630' 8" 15,100 500' 8" 11,000 320' 8" 7,040 1,050' 8" 23,100 2,300' 8" 50,600 730' 12" 24,090 3,800' 8" 83,600 300' 12" 9,900 1,740' 8" 38,280 1,300' 8" 28,600 1,315' 8" 28,930 1,300' 8" 28,600 1,290' 8" 28,380 660' 6" 10,840 2,700' 8" 59,400 60.000 Subtotal $591,060 • JERRY P. HARRIS. President GECRGE ?L'."'. MBERG. Secretary DAN CALCWELL. Commissioner Water 21i/ric1 7o. 75, Jn County Teieonone 624 0375 P 0. Box 68100. Riverton Neignts Station SEATTLE. WASHINGTON 98188 January 4, 1985 Mr. Brad Collins, Planning Director City of Tukwila Planning Department 6200 Southcenter Boulevard Tukwila, Washington 98188 W. Thorpe & Associates 815 Seattle Tower Third & University Seattle, Washington 98101 Re: Draft EIS, Valley View Estates 1984 Gentlemen: KEN E HALL MARION HARTER Mi ^ace• Office 19@53 22th Avenue So Highline water district intertie Water district 75 intertie Water district #75 intertie Water District No. 75 finds it highly impractical in view of the newly - passed Water System Coordination Act for the City of Tukwila to extend a dead end main into our corporate boundary to serve property where the District has existing facilities. Our Comprehensive Plan contemplates looping our existing system from Slade Way along 54th Avenue South to connect to an existing line on S. 166th Street. We are not anxious to continue the flushing programs necessary for the existing dead end mains. Another dead end main installed using City of Tukwila facilities will only contribute to an existing bad situation. The District feels it may also be appropriate to discuss with Tukwila an intertie at the PRV facility on 53rd Avenue South. We do .not desire this potential customer to withdraw from our corporate boundary, nor are we interested in a service area agreement to allow Tukwila to serve a customer we are better equipped to serve. City of Tukwila Planning Department and R. W. Thorpe & Associates Pace 2 January 4, 1985 We would be more than happy to discuss this project with the City of Tukwila Planning Department or the developer at their convenience. Please call Duane Huskey or myself should you have any questions. Sincerely, en Hall Administrative Manager KH: tmw cc: Dr. Herman Allenbach Puget Western, Inc. Paula Russell, Boundary Review Board COMMISSIONERS: B W BUTTfAS BETTY LUNZ MrC.AEL J WEST • SEWER DISTRICT 14816 MILITARY ROAD SOUTH P.O. BOX 68063 SEATTLE WASHINGTON 98168 TELEPHONE: 242.3236 January 23, 1985 Brad Collins, Planning Director City of Tukwila Planning Department 6200 Southcenter Boulevard Tukwila, Wa. 98188 COMMENT ON VALLEY VIEW ESTATES DRAFT EIS MANAGER: JAN 2 81955 T J YATEUCM SUBJECT: Sanitary Sewers The comments made herein are in reference to the 12" sanitary sewer line owned and operated by the Val Vue Sewer District that traverses the proposed Valley View Estate site. The District and its consulting engin- eering firm, Yoshida, Inc., has reviewed the Draft EIS and the easement for the District's sewer line and has concluded that to case the sewer in those areas where buildings are to be built over the sewer may not be the best method or the most cost effective. Attached is a copy of the site utility plan (Figure 16) on page 130. The District's recommended method is to relocate a portion of the existing 12" sewer line. This is indicated in orange on the revised site utility plan. The relocation will eliminate the potential violation of the City's policy that prohibits placement of buildings on top of sewer lines. It will also eliminate the potential of a possible sewerage spill that could occur during the encasement of the sewer line. The relocation construction of the sewer line can occur without any disruption of service in the existing line. Should any further information or elaboration be required on this matter, please contact this office. Sincerely, VAL VUE SEWER DISTRICT T. /MATELICH Manager TJM /gbs Enc. END OF ATTACHMENT B :� • • MEMORANDUM From: Rick Beeler, D.C.D. Directo To: Kim Hart, Finance Dept. RE: Release Primark Funds Date: November 2, 1989 Please pay Jane Preuss of Urban Regional Research $1,000 per the attached invoice from funds deposited by Primark Inc. for this purpose. This $1,000 disbursement will eliminate any funds in this account. Thank you. URBAN REGIONAL RESEARCH Planning Consulting Services October 3, 1989 City of Tukwila Planning Department 6200 Southcenter Boulevard Tukwila, WA 98188 ATTENTION: L. Rick Beeler INVOICE: PREPARATION OF EIS SCOPE FOR SYLVAN GLEN Jane Preuss 11.5 hours 4 $65 s 748.00 Clerical 9 0 hours 0 $28 $ 252.00 TOTAL AMOUNT DUE 1,000.00 Suite 1000 Tower Building 1809 Seventh Avenue WA 98101 () 6244889 A & C FILE# • ,-"" �� DATE 7 CO EP- 6,/55, CONSULTANT SERVICES EMENT `12 THIS AGREEMENT, entered into as of this 27th day of July, 1989, is by and between the City of Tukwila, a Municipal Corporation, hereinafter referred to as the "City" and Jane Preuss, hereinafter referred to as the "Consultant ". WHEREAS, the City desires to retain the services of a consultant to complete the scope of work for an environmental impact statement; and WHEREAS, the Consultant is qualified, willing and able to provide and perform said services described in this agreement; and WHEREAS, the said services to be performed by the Consultant are temporary in nature. NOW THEREFORE, in consideration of the mutual promises and covenants herein contained, to be kept, performed and fulfilled by the respective parties thereto, and other good consideration, is mutually agreed as follows: 1. The Consultant shall assist the Community Development Department by preparing a final "scope of work" for the Sylvan Glen Environmental Impact Statement (File No.: EPIC -4 -89) and shall complete all work in a manner pursuant to the understandings and agreement in Exhibit A. 2. The City agrees to pay the Consultant $1,000,00 for services performed under this contract. Such payment shall constitute the consultant's sole compensation for the contract services performed for the City. The Consultant shall submit invoices to the City not more often than once a month, which shall be based upon completion of the scope of work. Consultant Service Agreement July 25, 1989 Page 2 The payment to the Consultant shall be payable to and mailed to the following address: Jane Preuss Urban Regional Research Suite 100, Tower Building Seventh and Olive Seattle, WA 98101 3. The term of this agreement shall be through August 31, 1989 unless terminated earlier or extended for an additional period as provided under the following section hereof. 4. This agreement may be extended for an additional period upon the written consent of both parties hereto. This agreement may be terminated at will by either Party on ten (10) days written notice to the other, except that if either Party fails to perform or observe any of the provisions, terms, or conditions herein, either Party may terminate this agreement immediately, so long as written notice is thereafter communicated to the other. 5. Said services, and shall be conducted in accordance with performance. all duties incidental or necessary thereto and performed diligently and competently and professional standards of conduct and 6. All records or papers of any sort relating to the City and the project will at all times be the property of the City and shall be surrendered to the City upon demand. All information concerning the City and said project, which is not otherwise a matter of public record or required by law to be made public, is confidential and the Consultant will not, in whole or in part, now or.at any time disclose that information without the • • Consultant Service Agreement July 25, 1989 Page 2 express consent of the City. 7. This agreement may not be assigned or otherwise transferred by either party hereto. The Consultant may hire a portion of the work to be done by others provided the Consultant receives written consent of the City. 8. No change, alternation, modification or addition to this agreement will be effective unless it is in writing and properly signed by both parties. IN WITNESS WHEREOF, the parties hereto have signed this agreement on the day and year first above written. Approved as to form: con -agent 7 -24 -89 Community Development Director y Administrator • EXHIBIT A CONSULTANT'S STATEMENT OF UNDERSTANDING AND AGREEMENT FOR PREPARING ENVIRONMENTAL IMPACT STATEMENTS Environmental impact statement consultants shall govern their behavior by the following understandings and agreements. This is to ensure the preparation of an objective, unbiased document, and avoid the appearance of a conflict of interest. The consultant understands: 1. WAC 197 - 11-420 stipulates that preparation of Draft and Final EIS' is the responsibility of the DCD by or under the direction of its responsible official. 2. DCD will assure that the EIS is prepared in a professional manner and with appropriate interdisciplinary methodology. 3. DCD will direct the areas of research and examination to be undertaken as a result of the scoping process, as well as determine the organization of the resulting document. 4. DCD will supervise the EIS preparation process and will approve the document for publication only when the DCD is satisfied it complies with the spirit of RCW 43.21C and the SEPA Rules (WAC 197 -11). The consultant agrees: 1. EIS preparation will be as objective and unbiased as possible in order to achieve a legally adequate document. When necessary, the consultant shall participate with DCD in demonstrating EIS adequacy if the EIS is challenged. 2. Persons who participate in preparation of a directed EIS are considered agents for Tukwila's Department of Community Development (DCD) in achieving an adequate document. When adequacy of an EIS is challenged, persons who have participated in EIS preparation shall continue in their capacity as an agent for the DCD. The EIS consultant shall not act as an advocate for a project proponent in SEPA appeals, to avoid the potential appearance of a conflict of interest. To participate in the preparation of the EIS under the direction of DCD. Preliminary drafts of the EIS or sections of the EIS will be submitted directly to the DCD for review and not to the project proponent or the proponent's representatives for preliminary review. Applicant's review copies shall be distributed only through the DCD. • Law Offices HANSON, BAKER, LUDLOW AND DRUMHELLER, P.S. • John M. Baker II Betty L. Drumheller Janet Gray John E. Hanson John T. Ludlow John T. McLean Paul D. Rytting Linda M. Youngs William E. Zwink (1980) VIA FACSIMILE (433 -1833) Mr. Rick Beeler Director Planning Department CITY OF TUKWILA 6200 Southcenter Boulevard Tukwila, Washington 98188 300 Surley Building 0 C T "9 1777 Main Street 1 1989 > llevue, Washington 98004 (206) 454 -3374 C r FAX (206) 454 -0087 r - -. l�¢ln_ October 18, 1989 Re: Primark Application for Apartment Development On the Ray Flink Property Dear Rick: A problem has arisen with this application which I hope you can resolve quickly. When I spoke with you last, you said you had approved the scope of the EIS changes and told me to have Jane Preuss get in touch with Vernon Umetsu. Vernon had received some proposed changes to the scope from Guy Spencer at Primark, and it was our understanding that Vernon had approved those changes and needed merely to check with you. I assume when he checked with you that he presented you with the changes that had been sent over by Primark. Apparently, Vernon now takes the position that deep soil borings are required for the EIS. This issue was resolved several months ago and, if imposed by the City of Tukwila, makes the project economically unfeasible. On June 28, 19.89, a meeting was held in Tukwila to discuss the soil boring issue. The people attending the meeting were Jack Pace, Vernon Umetsu (who, to my recollection, was in and out of the meeting), Jane,,,Preuss, Craig LaVielle, and Ken Haskell of Golder & Asociates, Primark'-s,soils consultants, Ron Cameron and me. There was considerable discussion considering whether or not deep borings were required for the EIS. As we discussed the issue, it became clear to all of us that no one at the City really had the expertise to determine whether or not deep 'b'orings were required. This issue was to be left to Dames & Moore, your consultants/ Golder & Associates was of the • Law Offices HANSON, BAKER, LUDLOW AND DRUMHELLER, P.S. Mr. Rick Beeler October 17, 1989 Page 2 opinion that they could provide ample information concerning overall soil stability without doing the deep borings at this time. Jack Pace, in fact, suggested that we allow Golder & Associates to submit their report as part of the EIS. That report would then be reviewed by Dames & Moore, and if they, in their professional judgment, were not satisfied with the analysis, they could require further studies. This solution seemed to make good sense, as none of us in the room, with the exception of the Golder & Associates people, had the expertise to determine what level of analysis was necessary. We understood that the requirement for deep borings as part of the soils analysis would be eliminated from the initial scope. If Dames & Moore is not satisfied with the analysis they receive from Golder & Associates, then we will all reevaluate the need for further work. The purpose of an EIS is not to run a project into the ground, but to provide an adequate level of environmental review. If this very expensive analysis is not eliminated, Primark will be obligated to terminate the project. Primark recognizes that before the units are constructed, this level of soils analysis will be necessary. They intend to do deep borings in conjunction with building design. It is not reasonable, however, to require the soils analysis necessary for construction when Primark does not even know if the rezone will be granted. We hope there has been a misunderstanding concerning the deep boring issue and that this element of the scope can be removed immediately so the project can proceed. Please contact me today, if possible, with your response. LMY /nd cc: .Ms. Jane Preuss Mr. Ray Flink Mr. Hong Tan, Primark Corporation 4897Y -14Y Very truly yours, HANSON, BAKER, LUDLOW AND DRU»HELLER, P.S. Linda M. You '1 16:37 '8`206 246 8154 • PR I MARK -, ..- • fj 001 PREMARK DATE: ys-/e FACSIMILE COVER LETTER T0: A4en 4/77(,( FAX # 3 3 /63_3 (://7,/ eV) Tc4w/ /B / /7iiin FROM: 6GLI/ `%�jj��- FAX # ( 206) 246 -8154 i MESSAGE /COMMENTS: M7 tee.,- 5 en Sy /i. /.�1 5 /. S d are-. aei /d - /pi 4'r77 a ' YD artj :�`iv ,,,s ,ot,// cLi1j'4f TOTAL NUMBER OF PAGES INCLUDING THIS COVER SHEET 102 - 1200 S. 192nd Street Seattle, Washington 98148 (206) 241 -6241 UWOO /O J lb:. l CLbb Lob Olb4 PKII`7AKK IQ](NZ s Proposed modifications to wording ot Ei.S scope for Sylvan Glen (EPIC -4 -89) PART 1: INTRODUCTION A. ALTERNATIVES TO BE EVALUATED I N THE U . E . 1 . S . 2. Project with South 178th Street realignment. ttealaanmenr_ as determined with city engineer; number ot units to remain the same as proposal. 5. No action A description of all alternotivec chill be provided with the same level of detail as the proposed action including, but not limited to: plan view, elevations, cross- sections, and grade and fill plan. Cross-sections shall indicate ,,,,y,,.� foundation oncept . - A.e. &A. I �Q • ` 4.,6P" aij "" of e , eedZ�L`Da p...- A preliminary site lan of alt#Vnat .- )- _ lie reviewed by the SEPA'official prior to design of elevation- and detailed" grading design. PART II: ELEMENTS OF THE NATURAL ENVIRONMENT A. EARTH Discussion based on the geotechnical report by Golder Associates as reviewed by Dames and Moore. The report snail consider the following: Existing Conditions 1. Ground surface pr_otiles, indicating original and proposed grades. Such profiles shall be estimated beyond property lines in the vicinity of South 178th Street where necessary to evaluate con• ti.ns .hic m-y affect the site or adiacent to c - 4 i' 0 (rxArl' A site topographic survey by a licensed surveyor at a minimum 40 foot-scale shall show existing contour lines with shot �- locations and elevations noted, existing structures and ^ street right -of -way. 2. Description of subsurface conditions including geology soil /bedrock stratigraphy, slope stability, groundwater conditions, and engineering characteristics. 3. History of site conditions will also be documented based on review of: a. Washington State Department ot Transportation construction records for 1 -5 and South 178th Street. 09/05/89 16:38 V206 246 8154 v • . 1 Pw-, PKIMAKK • b. City of Tukwila Public Works Engineering Department information. c. Sensitive Areas Map Folio for King County, - shingtor December 19 8 7. d. Aerial photographs. Impacts tgj bb.S 1. Description of propose: structure and utilities. 2. Approximate floor grades /excavation levels of oroposal. 3. Discussion ot how the proposed development affects t:lle stability of the site and adjoining properties during ano after construction, including a statement ot the relative risks at each stage. 4. Existing and finished grades, grading and earthwork, including compaction and fill._.material specifications, use ot site soils as fill or backf.iliy imported till /backtiil specifications, height and inclination of slopes. 5. Assessment of drainage /erosion hazards on site dur.i.na and attet gun iLnLLiuri in regard to the proposed building and grading plans. Mitigating Measures Specific measures for avoiding adverse impacts: in the short term, during construction. 2p. in the long term, after construction. B. WATER Existing Conditions 1. Surface water areas in vicinity to be inventoried. 2. Subsurface water covered under "Earth." Impacts and Mitigating Measures 1. Alternative measures to mitigate drainage impacts to ne explored include on -site retention and upgrading the storm water pump Station at South 17Sth Street and Snnthdenter Parkway. 2. Groundwater impacts and mitigating measures will be evaluated in the geotechnical analysis, and addressed in the "Earth" section. ` 09/05/89 16:39 1106 246 8154 C. NOISE PRIMARK • Document how contiqurati6n oi„—si-L- adjoining topography to west, and distance from freeway, act to buffer arolect from freeway noise. if freeway noise is a significant component or ambient noise levels on site, and ambient levels exceed those generally acceptable due to freeway noise, identity mitigating measures. PART III: ELEMENTS OF THE BUILT ENVIRONMENT C. TRANSPORTATION 3. South 178th Street is not available as year -round street due to 21% grades; identify emergency access for fire, police, and ambulance, existing and as proposed by mutual aid pact for fire and emergency medical. 4. (replace with contents of item 5.) 5. (now is item number 4.) 4004 1909 DATE /TIME• TO: JANE PRUESS 621 -0531 (Name) (Company Name) (FAX #) City of Tukwila PLANNING DEPARTMENT 6200 Southcenter Boulevard Tukwila, Washington 98188 (206) 433 -1849 FAX TRANSMISSION AUGUST 29, 1989 1:15 P.M. FROM: VERNON UMETSU FAX #: 433 -1833 PHONE NO. 433 -1858 SUBJECT: ATTACHED LETTER RE EIS SCOPING FOR SYLVAN GLEN PAGE(s):_8_(+ Cover Sheet) COMMENTS: CITY OF TUKWILA 6200 ;(11.THCE. VIER BOULEVARD. TUKWILA. 1V.4SHI.VGTO.V 98188 August 28, 1989 Hong Tan Primark 1200 South 192nd St. Suite 102 Seattle, WA 98148 PHONE 4 (206) 433.1800 Gary L. 1 jnDuse n. Mayor RE: EIS Scoping for Sylvan Glen (EPIC- 4 -89). Dear Mr. Tan: I have reviewed your materials and the responses received during the E.I.S. comment period, and determined that a limited scope E.I.S. is required. The document will addresses the areas of Earth, Air, Water, Noise, Land Use, Aesthetics, Transportation, and Utilities per the document outline in Attachment A. Please review the attached scope and contact Vernon Umetsu of my staff by September 5, 1989 with your comments. The E.I.S. scope will be finalized after this date, the consultant's contract cost negotiated, and a contract between consultant and City prepared for your review. Draft E.I.S. contracts are generally negotiated on a fixed cost basis. Final E.I.S. costs will be negotiated later once comments have been received. The contract will be executed and work authorized by the City upon receipt of a check for the total estimated amount. Vernon Umetsu will be working with you as the City's project planner and is available to answer any general questions. Specific technical questions should be resolved directly with the appropriate departments. S . Rick Beeler SEPA Responsible Official cc: Ray Flink c/o Betty Drumheller ATTACHMENT A Sylvan Glen Draft Environmental Impact Statement Contents /Consultant Scope of Work The contents of the following sections shall clearly evaluate existing conditions, project impacts, mitigating measures and unavoidable adverse impacts in light of the City's comments. PART I: INTRODUCTION Title Page Preface Fact Sheet Table of Contents List of Tables List of Figures Summary of Impacts and Mitigating Measures Description of Proposed Action Project description shall include, but not be limited to materials required for Board of 'Architectural Review submittal: A. ALTERNATIVES TO BE EVALUATED IN THE D.E.I.S. 1. The Proposed Action Without realignment of South 178th Street. 2. Project with South 178th Street realignment LA4AA-44"iieA— "A Realignment as determined by city engineer; 41enegiveof to remain the same as proposal. 3. Proposed action with two story units grouped along public street frontages. 4. Office rather than multi - family use. 5. No action. A description of all alternatives shall be provided with the same level of detail as the proposed action including, but not limited • plan view, elevations, cross - sections, grade and fill plan, an• Via+ structural engineering (to be coordinated with engineering safety factor calculations in Earth). r"A preliminary site plan of alternatives shall be approved by the SEPA Official prior to detailed design. PART II: ELEMENTS OF THE NATURAL ENVIRONMENT A. EARTH Discussion based on the geotechnical report by Golder Associates as rev ' ewed by Dames and Moore ?, 7:0„, c�=Q,- ,,��.-a. ,,tie. Exist ng Conditions 1. Ground surface profiles4, indicating original and proposed grades. Such profil.s; shall be estimated beyond property lines in the vicinity of South 178th Street where necessary to evaluate conditions which may affect the site or adjacent sites. A site topographic survey by a licensed surveyo shall show existing contour lines with shot locations and elevations noted, surrounding properties, existing structures, street right -of -way. scale. r a a minimum (0 foot- 2. Description of subsurface conditions including geology, soil /bedrockstratigraphy, shallow and deep groundwater conditions,_ and engineering characteristics. Evaluation of the slope stability conditions of the site requires information on the geometry of any past slide, deep soil conditions, and groundwater elevations. Exploration logs and laboratory test results shall be —7 .);tros-7- ? provided. 3. History of site conditions will also be documented based on review of: a. Washington State Department of Transportation (WSDOT) Construction Records for I -5 and South 178th Street b. City of Tukwila Public Works Engineering Department information c. Sensitive areas Map Folio for Ring County, Washington, December 1987 d. Aerial photographs Impacts 1. Description of proposed structure and utilities including 'r 2 the engineering safety factors.) 2. Approximate floor grades /excavation levels of proposal, 3. The present stability of the site, the stability during construction, and the stability of site areas after the proposed development is completed will be provided, including a statement of the relative risks at each stage, the slide potential relating to abutting properties, and stability under seismic conditions will be documented. 4. Existing and finished grades, grading and earthwork, includ- ing compaction and fill material requirements, use of site soils as fill or backfill, imported fill /backfill -e_ me s, height and inclination of slopes. -i 5. Assess drainage /erosion proposectpundation) and cent- rem. hazards on site in regard to the grading plans Mitigating Measures Specific measures for: 1. Short term construction period. 2. Long term recommended construction and structural design. B. WATER Existing Conditions 1. Surface water areas in vicinity to be inventoried. 2. Subsurface water covered under "Earth ". Impacts 1. To be addressed in Earth. The geotechnical analysis will evaluate ,• pacts and mitigating measures for site drainage. Mitigating Measures Alternative measures to mitigate drainage impacts to be explored include on -site retention and upgrading the pump station at South 178th Street /Southcenter Parkway. B. NOISE Existing Conditions /Impacts /Mitigating Measures Conduct a noise study to document the effect of freeway noise impacts upon the proposed development (i.e. living, sleeping, and recreation areas). Effect of site plan, proposed structures and adjoining topography on projected noise levels shall be documented. - _ _, _ _ - - .. The JGL noise study provides a useful prototype document for impact analysis and mitigating measures. PART III: ELEMENTS OF THE BUILT ENVIRONMENT A. LAND USE Existing Conditions Documentation should encompass the site and surrounding area from South 178th /South 180th to City limits, and from I -5 to 57th Street. Impacts Land use impacts to be evaluated for to each alternative. 1. Discuss whether the proposed change will significantly affect the viability of Comprehensive Plan land use designa- tions for adjacent properties. 2. Consistency of each alternative action and impacts with Comprehensive Plan land use policies and map, and environmental (steep slope) policies. 3. Discuss cumulative impacts of more intensive uses in terms -of capability of area utilities (water, sewer, transportation network) to support more intensive uses. 4. Please note that consistency with adopted plan elements is required for Comprehensive Plan amendments, including, but not be limited to South 178th /South 188th Street improve- ments. The Public Works Department should be contacted for determination of consistency with road and utility plans. Mitigating Measures Mitigating measures to be identified by alternative. B. AESTBBTICS Existing Conditions Views of project site must be documented from the four sites indicated on the attached map. Photographs may be required to clearly show the existing site, and as a base on which project alternatives will be shown. Impacts The proposed alternatives must be graphically superimposed onto existing conditions. Mitigating Measures Summarize mitigating characteristics of project design etc. C. TRANSPORTATION Existing Conditions Document existing LOS for South 178th /South 180th, Southcenter Parkway and South 180th /Military Road intersections, and Military Road /South 188th, trips, accident rates, and pedestrian facili- ties. Specific transportation system evaluations shall include: 1. Trip generation and distribution of ADT and PM peak hour traffic, and the following LOS intersection analyses: Southcenter Parkway /South 180th Street. LOS analysis shall be per the latest ITE capacity manual. 2. Vehicle and pedestrian safety analysis to include pedestrian walking routes, school routes, and school and Metro bus accessibility. 3. South 178th Street is not available as year -round street due to 21% grades demonstrate alternative alignments for South}a '"' 178th Street. J 4. Identify emergency access for fire, police, and ambulance, existing and as proposed by mutual aid pact for fire and emergency medical. 5. Identify King County and WSDOT requirements for new I -5 freeway ramps at its intersection with South 178th Street. Impacts 1. Trip generation, travel pattern, and road capacity analysis per direction of the City Engineer to address impacts on above existing conditions. 2. Consistency of development with Six Year Transportation Improvement Plan. Consult City Engineer for demonstrating proposed project has made provision for the South 188th /South 178th Street improvements. 3. Consistency of internal circulation pattern with Fire Department and Public Works standards. Mitigating Measures 1. Evaluate the need for specific road improvements to mitigate immediate development impacts, the need for a no protest agreement for the formation of an R.I.D. to provide the project's fair share in resolving cumulative transportation impacts, and pedestrian improvements. • • 2. Identify mitigation and funding sources (LID participation, etc.) for safety and capacity impacts including the vehicle, pedestrian, and emergency access. D. UTILITIES Existing Conditions 1. Describe existing facilities on and adjacent to site: access points, and system capacity. Complete a sewer, water, storm drainage capacity analysis. Reference impacts of cumulative land use changes in Land Use. Please note that storm drainage system capacity is especially limited in this area. 2. Certification of water availability from W.D. No. 75 shall be required. Tukwila fire pressure and flow standards shall be satisfied and documented. 3. An engineering analysis of sewer availability at the site and sewer system capacity to satisfy project demand shall be conducted. Horton Dennis (Marty Penhallgram) has recently completed an evaluation of sewer capacity in the area. Impacts Identify impacts of failed systems. Evaluate the need to provide for the impacts of failed sewer and water systems (i.e. by thrust blocks, double walled pipes, and regular maintenance). Mitigating Measures Identify specific improvements to system capacity to satisfy the immediate needs of the project, and any "no protest" L.I.D. agreements which should be executed to ensure the project pays its fair share of cumulative system improvement needs. APPENDIX Distribution List and Mailing Labels D,0V 70 1�i�2 C eg�Z A?' f/ .% /422moAz (.2.1 -t e ( K- /8s8 , F /niA S , CoK TW T S YC vAA( G C_ E■,( /¢4 k 73, OK " 8 /i .S- /8 y rev' c„ )g T sC-661 Tom/ S /s TIC F/nrA S sco /c c-✓'1/ C `eleC EA S(S Fob A Co K S v c_TA-K T : C4', •c 7 4- L.T. 0 T'I S Co At 72ACT 4C au /46--S Co c W. C/ L PP/zo vs}- • AwY CS To TEt. S COP C 26f-QV o,,1 G GK -re CO v"‘ Ct c: Fog A- co At Tt4 CT cub M sw.775 /ok! 11-D / 77on/ T o G o t nc_.G T O 4-P Pc r c.4 N T • . 'a To Fv ,va 7774(S Do cc) (KIT P4,6-As e- ,ye- flu PA- R eD c 7� A_ cress r o.Vs anc i Hine. S »4y, LA 2G PR:o M4-r S ,4-K.0 A--r- M Y 7) CSK, • _412. (.t4 ( .r P "A L E, /- 5- -- C 0 Ac z-eW T ot Y _ vtetAi —G 67_V,01 -1 ARTY, _OK STEP c.Je 7 Sc aR;S — D ) 4 - 7 - - ! /' 5 -/ c 7 14f / S �S - TffC - P2ofos�D F/A 1 S - -S_co Pc- t C �' - w t L 8E e t SL S Fok A — Co "(S_v c-7A! -T _ Ci∎` ?WA- 7). O T E ¢ l _ S _ . Go_Ai T24GT ___46- a va. S___- co c} CI-.L.. Ace P /_Zo_-ILA- L o A'At ---- [.AT_ &"7_2- C-60+1,4 G_C 5. o G - GK -- 7o .v - Fog /4' Me-- N1) M s-t.c T by AD /770",e Fo t $ 7-0 F_u_%vL _ -riWS Do_ c,ciei CKIT P4-6Se--- ot.L %Hv2Sb ry_,_ LA 2G _P� -O SLrLT - M S --4 7 ASK-. • 1 August 9, 1989 Hong Tan Primark 1200 South 192nd St. Suite 102 Seattle, WA 98148 RE: EIS Scoping for Sylvan Glen (EPIC- 4 -89). Dear Mr. Tan: I have reviewed your materials and the responses received during the E.I.S. comment period, and determined that a limited scope E.I.S. is required. The document will addresses the areas of Earth, Air, Water, Noise, Land Use, Aesthetics, Transportation, and Utilities per the document outline in Attachment A. Please review the attached scope and contact me by September 5, 1989 with your comments. The E.I.S. scope will be finalized after this date, the consultant's contract cost negotiated, and a contract between consultant and City prepared for your review. The City generally caps D.E.I.S. contracts with a maximum dollar amount. Final E.I.S. costs will be negotiated later once comments have been received. The contract will be executed and work authorized by the City upon receipt of a check for the total estimated amount. Vernon Umetsu, on my staff, will continue to be available to work with you on this project. Specific technical questions should be resolved directly with the appropriate departments. Sincerely, Rick Beeler cc: Ray Flink c/o Betty Drumheller • • Betty Drumheller Hanson, Baker, Ludlow and Drumheller, P.S. 300 Surrey Building 10777 Main Street Bellevue, WA 98004 454 -3374 • • ATTACHMENT A Sylvan Glen Draft Environmental Impact Statement Contents /Consultant Scope of Work The contents of the following sections shall clearly evaluate existing conditions, project impacts, mitigating measures and unavoidable adverse impacts in light of the City's comments. PART I: INTRODUCTION Title Page Preface Fact Sheet Table of Contents List of Tables List of Figures Summary of Impacts and Mitigating Measures Description of Proposed Action Project description shall include, but not be limited to materials required for Board of Architectural Review submittal: A. ALTERNATIVES TO BE EVALUATED IN THE D.E.I.S. 1. The Proposed Action Without realignment of South 178th Street. 2. Project with South 178th Street realignment Realignment as determined by city engineer; density to remain the same as proposal. 3. Proposed action with two story units grouped along public street frontages. 4. Office rather than multi - family use. 5. No action. A description of all alternatives shall be provided with the same level of detail as the proposed action including, but not limited to: plan view, elevations, cross - sections, grade and fill plan, typical foundation type, and structural system. A preliminary site plan of alternatives shall be approved by the SEPA Official prior to detailed design. • • PART II: ELEMENTS OF THE NATURAL ENVIRONMENT A. EARTH Discussion based on the geotechnical report by Golder Associates as reviewed by Dames and Moore: Existing Conditions 1. Ground surface profile(s), indicating original and proposed grades. Such profile(s) shall be estimated beyond property lines in the vicinity of South 178th Street where necessary to evaluate conditions which may affect the site or adjacent sites. A site topographic survey by a licensed surveyor shall show existing contour lines with shot locations and elevations noted, surrounding properties, existing structures, street right -of -way. and plan view of the site relative to the proposed development shall be provided at a minimum 40 foot scale. 2. Description of subsurface conditions including geology, soil /bedrock stratigraphy, groundwater conditions, and engineering characteristics. Evaluation of the slope stability conditions of the site requires information on the geometry of any past slide, deep soil conditions, and groundwater elevations. Exploration logs and laboratory test results shall be provided. 3. History of site conditions will also be documented based on review of: a. Washington State Department of Transportation (WSDOT) Construction Records for I -5 and South 178th Street b. City of Tukwila Public Works Engineering Department information c. Sensitive areas Map Folio for King County, Washington, December 1987 d. Aerial photographs Impacts 1. Description of proposed structure and utilities 2. Approximate floor grades /excavation levels of proposal 3. The present stability of the site, the stability during construction, and the stability of the site after the proposed development is completed will be provided, including a statement of the relative risks at each stage, the slide potential relating to abutting properties, and stability under seismic conditions will be documented. 4. Existing and finished grades, grading and earthwork, includ- ing compaction and fill material requirements, use of site soils as fill or backfill, imported fill /backfill require- ments, height and inclination of slopes. 5. Assess drainage /erosion hazards on site in regard to the proposed foundation and grading plans, and during construction. Mitigating Measures Specific measures for: 1. Short term construction period. 2. Long term recommended construction and structural design. B. WATER Existing Conditions 1. Surface water areas in vicinity to be inventoried. 2. Subsurface water covered under "Earth ". Impacts 1. To be addressed in Earth. The geotechnical analysis will evaluate impacts and mitigating measures for site drainage. Mitigating Measures Alternative measures to mitigate drainage impacts to be explored include on -site retention and upgrading the pump station at South 178th Street /Southcenter Parkway. • • NOISE Existing Conditions /Impacts /Mitigating Measures Conduct a noise study to document the effect of proposed structures and adjoining topography on Existing noise conditions shall be established. study provides a useful proto -type document for and mitigating measures. PART III: ELEMENTS OF THE BUILT ENVIRONMENT A. LAND USE Existing Conditions site plan, freeway noise. The JGL noise impact analysis Documentation should encompass the site and surrounding area from South 178th /South 180th to City limits, and from I -5 to 57th Street. Impacts 1. Discuss whether the proposed change will significantly affect the viability of Comprehensive Plan land use designa- tions for adjacent properties. 2. Consistency of each alternative action and impacts with Comprehensive Plan land use policies and map, and environmental (steep slope) policies. 3. Discuss cumulative impacts of more intensive uses in terms of capability of area utilities (water, sewer, transportation network) to support more intensive uses. 4. Please note that consistency with adopted plan elements is required for Comprehensive Plan amendments, including, but not be limited to South 178th /South 188th Street improve- ments. The Public Works Department should be contacted for determination of consistency with road and utility plans. Mitigating Measures Land use impacts to be addressed by alternatives. B. AESTHETICS Existing Conditions Views of the project must be documented from the four sites indicated on the attached map. • • Impacts The proposed action must be graphically superimposed onto existing conditions. Mitigating Measures See Alternatives. D. TRANSPORTATION Existing Conditions Document existing LOS for South 178th /South 180th, Southcenter Parkway and South 180th /Military Road intersections, and Military Road /South 188th, trips, accident rates, and pedestrian facili- ties. Specific transportation system evaluations shall include: 1. Trip generation and distribution of ADT and PM peak hour traffic, and the following LOS intersection analyses: Southcenter Parkway /South 180th Street. LOS analysis shall be per the latest ITE capacity manual. 2. Vehicle and pedestrian safety analysis to include pedestrian walking routes, school routes, and school and Metro bus accessibility. 3. South 178th Street is not available as year -round street due to 21% grades demonstrate alternative alignments for South 178th Street. 4. Identify emergency access for fire, police, and ambulance, existing and as proposed by mutual aid pact for fire and emergency medical. 5. Identify King County and WSDOT requirements for new I -5 freeway ramps at its intersection with South 178th Street. Impacts Trip generation, travel pattern, and road capacity analysis per direction of the City Engineer to address impacts on above existing conditions. Consistency of development with Six Year Transportation Improvement Plan. Consult City Engineer for demonstrating proposed project has made provision for the South 188th /South 178th Street improvements. Consistency of internal circulation pattern with Fire Department and Public Works standards. • • Mitigating Measures Evaluate the need for specific road improvements to mitigate immediate development impacts, the need for a no protest agreement for the formation of an R.I.D. to provide the project's fair share in resolving cumulative transportation impacts, and pedestrian improvements. Identify mitigation and funding sources (LID participation, etc.) for safety and capacity impacts including the vehicle, pedestrian, and emergency access. D. UTILITIES Existing Conditions Describe existing facilities on and adjacent to site: access points, and system capacity. Complete a sewer, water, storm drainage capacity analysis. Reference impacts of cumulative land use changes in Land Use. Please note that storm drainage system capacity is especially limited in this area. Certification of water availability from W.D. No. 75 shall be required. Tukwila fire pressure and flow standards shall be satisfied and documented. An engineering analysis of sewer sewer system capacity to satisfy conducted. Horton Dennis (Marty completed an evaluation of sewer Impacts availability at the site and project demand shall be Penhallgram) has recently capacity in the area. Identify impacts of failed systems. Evaluate the need to provide for the impacts of failed sewer and water systems (i.e. by thrust blocks, double walled pipes, and regular maintenance). Mitigating Measures Identify specific improvements to system capacity to satisfy the immediate needs of the project, and any "no protest" L.I.D. agreements which should be executed to ensure the project pays its fair share of cumulative system improvement needs. APPENDIX Distribution List and Mailing Labels ci# PRIMARK • JUL a1989 4 June 29, 1989 Jack Pace Senior Planner City of Tukwila 6200 Southcenter Boulevard Tukwila, Washington 98188 Re: Sylvan Glen Dear Mr. Pace: The purpose of this letter is to confirm that submittal for Sylvan Glen consists of the following applications: Comprehensive Plan Amendment Rezone Application to R -4 PRD Application Please note that the PRD Application will be in lieu of the Binding Site Plan Commitment u der the Subdivision Code which was requested under our .ubmittal transmitted to you on February 22, 1989. cc: Vernon Umetsu 102 - 1200 S. 192nd Street Seattle, Washington 98148 (206) 241 -6241 Hong Tan President ;i•. "�-_- +ids,. s Golder Associates Inc, CONSULTING ENGINEERS June 27, 1989 City of Tukwila Planning Department 6200 Southcenter Blvd. Tukwila, Washington 98188 ATTENTION: Jack Pace, Senior Planner RE: EIS GEOTECHNICAL CONTRIBUTION SYLVAN GLEN APARTMENTS TUKWILA, WASHINGTON 254;6-1C I T'r - CF TUKW I LH ;# RECEIVED CITY OF TUKWILA JUN 2 7 1989 BUILDING um„'. Our ref: 893 -1005 Dear Mr. Pace: Our firm has been asked to contribute the geotechnical (Soil, Erosion, Slope Stability and Groundwater) portions of the environmental impact statement (EIS) for the proposed Sylvan Glen apartments in Tukwila, Washington. We appreciate this opportunity and look forward to preparing our contribution to the EIS. We have prepared a preliminary geotechnical exploration and engineering report for project, dated February 20, 1989. We anticipate the field dated gathered as part of the preliminary report will be sufficient to allow us to address the pertinent issues for the project and complete our contribution to the EIS. We have attached a brief outline of the geotechnical issues we will address in the proposed EIS for Sylvan Glen. If you have any questions please call. Sincerely, GOLDER ASSOCIATES INC. LaVielle, P.E. Senior Engineer 2 (/8 t Lea- GOLDER As8CCIATES INC. • 4i0• • 148TH AvENUE N.E„ REDMOND (SEATTLE), WASHINGTON, U.B.A. 98052 • TEL. (208) 889 -0777 • FACSIMILE (208) B8$6498 • TELEX 3106002944 OFFICES IN CANADA • UNITED. STATES • UNITED KINGDOM • SWEDEN • AUSTRALIA UG X49 C1Tl' OF TLkLJ1LH ;## .y. SYLVAN GLEN PROTECT EIS OUTLINE (EARTH AND WATER) 1. EARTH A. EXISTING CONDITIONS 1. Topography 2. Soils 3. Erosion 4 -. Slope Stability B. IMPACTS 1. Topography 2. Soils a. Cuts and Fills b. Foundations 3. Erosion a. During Construction b. Post Construction 4. Slope Stability a. Landslide Stability b. Head Scarp Stability C. MITIGATING MEASURES 1. Erosion.. 2.. Stability II. WATER A. EXISTING CONDITIONS' 1. Groundwater 2. Surface Drainage B. IMPACTS 1. Drainage a. Surface Runoff b. Intercepted Springs 2. Dewatering a. Impacts on'Stability b. Impacts on Groundwater C. MITIGATING MEASURES 1. Drainage 2. Dewatering • if_ Mr. William Polk June 8, 1989 Page 2 ELEMENTS OF THE ENVIRONMENT A. Earth Discussion based on the geotechnical report, Dames and Moore revisions, and the following revisions to the SEPA checklist: a. Terrain is generally steep slopes with a bench; not rolling. b. Steepest slope is 1.67:1 (60 %); not 2:1 (50 %). c. Boring B -1 shows compressed organic and silt layers at 38 feet. This indicates variable soil conditions and the potential need for additional borings to determine depth to compact soils. The need for additional borings at each pile and structural support facility location shall be evaluated. Insufficient data is provided in boring logs. Additional data required includes providing piezometric information for groundwater and sampling date. d. No data has been submitted to substantiate a conclusion of no unstable soils in the immediate vicinity. Such a conclusion is inconsistent with the geotechnical finding of highly erodible soils on site, and City experiences with unstable slopes on similar, nearby sites (i.e. Valley View Apartments, and Sylvan Glen Apartments). A geotechnical study and structural engineering analysis will be required to evaluate site stability under existing and proposed conditions. An acceptable engineering safety factor shall be specified and compared with the alternatives This analysis shall include all down slope areas to the Levitz railroad spur and Southcenter Parkway. The City will have Dames and Moore evaluate all geotechnical /hydrological studies pursuant to the scope in Attachment A. Their evaluation shall be incorporated into the DEIS WSDOT evaluation of the project alternatives should be included as applicable. This shall include, but not be limited to impacts and mitigating measures surrounding the storm water line running across WSDOT property and into their system. e. Cross - sections primarily running east to west, will be required to show existing and finished grades, and improvements for all alternatives. All retaining wall and rockeries (max. ht. is 4 ft.) shall be shown. Cross - sections shall show the site at a minimum 30 ft. scale. A second set of smaller scale cross - sections shall show the site, existing and finished grades, and alternative improvements in relation to the remaining down slope area to the Levitz spur and Southcenter Parkway. Mr. William Polk June 8, 1989 Page 3 • • f. The highly erodible soils on site (per Geotech. Rept.) indicates a high erosion potential during and after construction. g. Additional information on erosion control facilities and implementation schedule must be submitted. At a minimum, this shall include evaluating the need for the following development phasing: i. Acquire easement to construct/maintain /repair the storm water line from the property boundary to WSDOT storm water system and construct storm water line with no detention on site to the maximum extent feasible. Any detention facilities required by WSDOT should be constructed down slope on the flats where failure would not be as catastrophic. If on -site detention is feasible, the engineering design safety factor shall be specified and approved by the Public Works Department. Specific recommendations shall not be limited to actual facility requirements such as double walled detention pipes and a regular monitoring schedule. ii. Build temporary on site storm water construction and erosion control systems. iii. Complete on -site road system including curbing. iv. Complete all . upslope improvements with immediate connection of roof drains to storm water system prior to start of down slope construction. This would minimize exposed erodible soils and runoff. An "as built" certified survey by a City selected surveyor on the eastern road curb and building foundation locations shall be required prior to starting work on eastern units. v. Phased construction of down slope units as possible. Phasing and construction practices to be per geotechnical study and as approved by the City. At a minimum, construction phasing will probably prohibit disturbing areas 20 ft. west of the existing eastern slope edge until all up slope structures and roads are completed. vi. All drainage facilities shall be sized for the 100 year event from the site to a public storm system. B. Air Quality Evaluate the long term air quality impacts from freeway originated pollutants, if any. If none, substantiate with a discussion. crcIPoF TUKWILA FAX TRANSMITTAL FAX NUMBER: (206) 433 -1833 TO: BILL BETCOCK DATE: FRIDAY, MAY 12, 1989 TITLE: FROM: VERNON UMETSU COMPANY: TUKWILA ASSOCIATES TITLE: ASSOCIATE PLANNER DEPARTMENT: sv: , vvx,,. , c.v v ..v,w,..... .........,......, ........ ...................... DEPARTMENT: COMMUNITY DEVELOPMENT A ._.. FAX NO. 1- 272 -5591 TOTAL NO. OF PAGES TRANSMITTED, INCLUDING THIS COVER SHEET: 8 SENT BY (INITIALS): WB •w o taWxctina AA :moo:a:WAMa k�rMc$0 .�xw SUBJECT: REVISED PROPOSAL - RAINIER RIDGE COMMENTS /MESSAGE: 4 3 IF THIS COMMUNICATION IS NOT CLEARLY RECEIVED, PLEASE CALL: Wendy at 433 -1849 y TUKWILA CITY HALL - 6200 Southcenter Boulevard, Tukwila WA 98188 - (206) 433 -1800 03/24/89 0 4TTA C f'f M etiv T �{ DAMES&. MOORE a(.)t Al. r,ar, r r NNW] 51J0 MARKET PLACE T.':V;_R.. _ 'it- Hr;,r A t �Nj , . EA'1TLE, WAS}•:E'�iiT. O.`. 1 :. '., (1, 0•1 ,;. 1/4,1. May 10, 1989 j The City of Tukwila 6200 Southcenter Boulevard 1 ukwila, Washington 98188 Attention: Mr. Phil Fraser Revised Proposal Review of Geotechnical Preliminary Plans Rainier Ridge for T1be Citv of Tukwila Gentlemen: Report and RECEIVED poi mg TUKWILA PUBLJC WORKS Dames & Moore is pleased to present this revise 1 proposal to review the geotechnical reports by Rittenhouse -Zeman & Associates and to review the geotechnical and hydrological aspects of the preliminary plans by Tritec Associates, Inc. We understand the purpose of this review is to determine what information is needed to decide that the proposed development will not have a geotechnical failure affecting safety and economics. The documents provided us for review are: I. "Subsurface Exploration and Geotechnical Engineering Report, Proposed Rainier Ridge Apartments, South 178th Street & Interstate 5, Tukwila, Washington," for Holly Homes Company, 8222 Washington Boulevard S.W., Tacoma, Washington, by Rittenhouse - Zewnu dt Associates, Inc., Dellevue, Washington, November, 1988. 2. Letter report, "Summary of COeotechnica1 Design Recommendations, Rainier Ridge Apartments: Eastern Buildings, Tukwila, Washington," for Holly Homes Company, by Rittenhouse -Zeman & Associates, Inc., 2l December 1988. 3. "Supplemental Subsurface Exploration and Geotechnical Engineering Report, Proposed Rainier Ridge Apartments, South 178th Street and Interstate 5, Tukwila, Washington," for Holly Homes Company, by Rittenhouse -Zeman & Associates, Inc., February 1989. 4. Luudseape Masterplan by Thomas Rengstoif, ASLA, no date. 5. Letter report, "Description of Foundations and First Floor Framing for Buildings A, B and C," by Robert Fossatti Associates, 3 April 1989. • DAMES& MOORE A Ilkt 1-F. >: x /riTi., PAR TNI;P.'U 1!!. The City of Tukwila May 10, 1989 Pap 2 6. Site Plan /Building Elevations, 8 sheets, by, William Polk Associates, no date. 7. Letter, "Rainier Ridge Apartments - SEPA Review," to Mr. L. Rick Beeler, Planning Director, City of Tukwila, from Mr. William B. Betlach, Project Manager, Tritec Associates, Inc., 3 April 1989. 8. Letter, "SR 5, MP 153.15 Vic., CS 1767, Status of Rainier Ridge Apartment Complex," to Mr. William B. Betlach, Tritec Associates, Inc., from Mr. James L. Lutz, WSDOT, 3 April 1989. 9. "Rainier Ridge Apartments, Noise Study," II? Triter Associates Inc., Silverdale, WA, from JGL Acoustics, Inc., Bellevue, WA, 3 April 1989. 18. 1`crmlt Application uocuments, Lrty 01 Tukwila. Spetificully, our scope includes the following: 1. Review the submitted documents for completeness and report on itemized deficiencies. 2. Evaluate the Rittenhouse -Zeman & Associates (RZA) site investigations to determine if the investigations included enough explpratory borings and excavation pits. 3. Review and evaluate the RZA geotechfical and groundwater analysis and design recommendations and conclusions that relate to: o Site Stability o I'oundations " Slopes o Retaining walls " Rockeries o Site drainage, permanent run -off control, upstream and downstream run -off effects and /or considerations 4. Evaluate acceptability of construction recommendations. ai • Temporary construction period run-off control " Construction limitations due to weather ERMES & MOOR E • -• • - -- ''S3i::;:.;i; ,1. yL L:`�I'i 6L+ PART1Jr1r!.:IC1' The City Of Tukwila May 10, 1989 Page 3 5. Evaluate suggested /recommended monitoring programs for construction and for design life of project. 6. Evaluate recommended maintenance agreements, particularly for drainage facilities. Also, uny suggested drainage casements and agreements. 7. Provide a written report and recommendations for approval /disapproval of permit based on the geotechnical and hydrological considerations. No independent analyses of existing data will beperformed and we will not acquire any new !site- specific subsurface data. We will complete our review within three weeks after receiving authorization. We will, in (submitting our report, identify areas where additie4a1 is necessary iv complete the review. We will conduct ally isvestifilibh in accordance, with our standard Schedule of Charges and billing rates shown on the enclosed Attachments A through C. For the scope outlined above, we estimate our fee will be between $6,000 to $7,500. The cost breakdown for our services is as follows: I Item 1 12 -4 5 i6 i 7 1 P1 i i jtiiI Management/ Dining, etc. Project Engineer/ Principal Support Man Hours Time Hours 12 25 5 6 -- 8 2 12 10 5 3 Ketmburslble & Eauioment 50 100 50 200 Total 1,100. 2,600 500 800 1,800 Estimuted Total 'UV Oft IMES & MOORE 4 rRt'f':• 'd.:• !.Il,'Mfl, VAR Et:iK'■Hl:' The City of 'Tukwila May 10, 1989 Page 4 It has bccn a pleasure preparing this proposal for you and we look forward to working with you on this project. If you have any questions, please call us. \firkin; vet y truly, DAMES & MOORE Iihrb4ns L. Chabra, P.E. Principal Engineer /Assmiiite Hl.0 :kh v: \kuh \suils\props \tukwlla.lta 05i1yr J,: 'T5: 46 ' 12206 448 7994 [DAMES /MOORE SEA i' Anir n% MES & M OORE .•\ r.:;rr...,Z!i jpiA!.!J .•1f? hb Phk.TN1,1“1111' EM LOYEE Harbans L. Chabra Lynn E. Morlan Kelly S. Merrill W. (Martin McCabe Richard D. Clark James Su Thomas McFarlane Ke 'in Lamb J. Wade Albert Corbin Ae Rubertis JeaJine Dorn NORTHWEST SOILS February 14, 19P9 PERSONNEL BILLIN4► RATES HOURLY RATE $127.01 85.00 78.29 78.29 61.38 54.10 42.20 42.20 50.35 33.20 30.65 Wo4d Processing 43.35 Accounting 43.35 Secfetarial 30.00 Attachment A - ._•0.5/10/89 115:46 448 7994', fi DAMES /MOORE ilp DAMES (Si MOORL Ap of st ;lr ?NAi.L!!dlttUI'AR!NL'U.J)-!IV SCHEDULE OF CiIARGES UNITED STATES The ciIimpensation to Dames & Moore for our professional services is based upon and measured by the following elements, which are computed as set forth below. 1.0 1't;RSONNEL CHARGES 1.1 Charges for employees arc Computed by multiplying the total direct salary cost of our personnel (expressed as an hourly rate) by a facto of 2.5. The total direct salary cost shall be a suns equal to the direst payroll cost (computed by dividing the annual payroll cost by 1,940 hours plus 40 percent of same to cover payroll taxes, insurance incident to employment, sick leave and other employee benefits, The time of a partn r or retained consultant devoted to the project is charged at an assigned billing rate. 1.2 The 40 percent employee benefit factor is used for work performed by personnel assigned to ofil+:es in the United States. For work performed by personnel in our offices in other countries. it will vary depending on the employee benefits paid in the particular location, 1.3 When outside the United States, employees' and partners' total direct salary cost will be increased by the premium customarily paid ' by otter organizations for work at that location. 1,4 I Time spent in either local or inter -city travel, when travel is in the interest of the work, will be charged for in accordance with the foregbing schedule; when traveling by public carrier, a maximum charge of 'eight hours per day will be made, 2.0 2.1 I 2.2 3.9 1 OTHER SERVICES AND SUPPLIES 3,1 `` Charges for services, equipment and facilities not furnished directly by Dames &. Moore, and any unusual items of expense not custdmarfly incunetl in our normal operations, are computed as follows. EQUIPMENT CHARGES Computer control of project costs will he billed at a rate of S I.25 Fier each 550 of fob charges ui fraction thereof. Other Dames & Moore equipment, if used, will be billed at the rates noted in the Appendix. 3.1.1 Coat plus 10 percent includes shipping charges, subsistetice, transportation, printing and reproduction, lung distance 1.;oinmunication, miscellaneous Supplies and rentals. 3.1.2 Cost plus 15 percent includes surveying services, land drilling equipment, construction equipment, testing laboratories, wntract labor. 3.1.3 Cost plus 25 percent includes aircraft. watercraft, helicopter and marine drilling equipment and operation. 111.5 (7•titt) r Attar ' i -rnaflt 13 RI 007 (/10/89 15:47 $2 448.7994' DAMES /M00RE SCHEDULE OF CHARGES — APPENDIX Dames & Moore EQUIPMENT i AWTOMOTIVE Vehicle, per hour (maximum of 8 hours per dray) $ 4.00 Mileage, per mile $ .25 SOIL Solis sampling and compaction control equipment, per shift hour $ 5.00 Sol sample rings and containers, per sample S 5.00 LABORATORY Sol, water and biologic testing equipment per employee, per !lour '� 10.06 D riarrlic Testing Equipment will be quoted as iequiiedl DIN I N G SCUBA diving, per diver, per clay . . . . . . . . . . . . . . . S 100.00 REPORT PREPARATION Wbrd Processing Equipment. per hour $ 10.00 1nHuuse Reproduction, per sheet S .10 ESIGINEERING COMPUTER SERVICES T e use of Dames & Moore's in -house computer facilities will he charged in accordance with the " ]engineering Computer Applications Billing Schedule" (attached). Computer time and other services provided by outside vendors will be charged at cost plus 15 %. Terminals, plotters, forms, an'd computer supplies will be charged at cost plus 15 %. FI;FLO Because of the varied nature of equipment. location and use, these rates will be quoted as required. 11.4 (REV. 2.82) Attachment. C 2008 • 1► METRO Municipality of Metropolitan Seattle Exchange Building • 821 Second Ave. • Seattle, WA 98104 -1598 April 13, 1989 Rick Beeler, Planning Director City of Tukwila 6200 Southcenter Blvd. Tukwila, Washington 98188 Determination of Significance File No.: EPIC -4 -89 PRIMARK CORP Dear Mr. Beeler: APR 181989 Metro staff offers the following scoping comments for the Sylvan Glen Project DEIS. o Surface water management design elements mitigating adverse impacts to the water quality of Green River should be identified and evaluated. o The DEIS should provide information regarding planned wastewater disposal system(s), projected peak and average wastewater flows, and impacts to downstream wastewater facilities. o The effectiveness of transportation demand management (TDM) actions to mitigate the project's traffic impacts needs to be evaluated. We look forward to the opportunity to review,and comment on the DEIS upon its release. Sincerely, Gregory M. Bush, Manager Environmental Planning Division GMB:jmg4591 5 CHRISTINE O. GREGOIRE Director • • STATE OF WASHINGTON DEPARTMENT OF ECOLOGY Mail Stop PV -11 • Olympia, Washington 98504 -8711 • (206) 459 -6000 April 10, 1989 Mr. Rick. Beeler City of Tukwila 6200 Southcenter Blvd. Tukwila, WA 98188 Dear Mr. Beeler: [\PR 1 L 1989 p Thank you for the opportunity to comment on the scoping no- tice for the construction of 144 apartment units by Primark Corporation (EPIC- 4 -89). We reviewed the environmental checklist and have the following comments. The geotechnical study mentions the presence of springs and a wet area on the project site. The draft environmental impact statement should include the results of an investigation of these areas and an evaluation of any wetlands on the site. If you have any questions, please call Mr. Andy McMillan of the Wetlands Section at (206) 438 -7428. Sincerely, Barbara J. Ritchie Environmental Review Section BJR: cc: Andy McMillan GARY F. FAULL PETER S. BANKS March 31, 1989 Mr. Rick Beeler Planning Director 6200 Southcenter Blvd. Tukwila, WA 98188 FAULL & BANKS ATTORNEYS AT LAW 321 BURNETT AVENUE SOUTH P. 0. BOX 26 RENTON, WASHINGTON 98057 (206) 255 -5600 Re: Environmental Impact Statement Input 18059 57th Ave. S. Project Dear Mr. Beeler: APR ° 3 1989 1 1 ii Please be advised that I am the attorney for Mr. and Mrs. Roy Martin whose property is contiguous with, the property being proposed rezone, etc. My clients are concerned about two things:. 1. The impact of any requirement for an increase in the capacity of the utilities, in particular, sewer and water lines. They do not feel they should be responsible for having to pay any costs attendant on that increase requirement if it is man- dated by the City. 2. They are concerned with the landscaping configuration that would cut off their view of Mount Rainier. Any correspondence from you I would appreciate having directed through my office as Mr. and Mrs. Martin may not be in residence during the impact statement procedure. RY F. F GFF %de.. cc: Roy - nd'Winona Martin • City of Tukwila PLANNING DEPARTMENT 6200 Southcenter Boulevard Tukwila, Washington 98188 (206) 433 -1849 DATE /TIME: TO. (Name) FAX TRANSMISSION TUESDAY, MARCH 28, 1989 LEGAL PUBLICATION DEPT (Company Name) FROM: JOANNE JOHNSON, PLANNING DEPT VALLEY DAILY NEWS (FAX #) -1 - /oO FAX #: 433 -1833 PHONE NO: 433 -1849 SUBJECT. PUBLICATION ON THURSDAY, MARCH 30, 1989 OF ATTACHED SCOPING NOTICE PAGE(s):_ 1 (+ Cover Sheet) AFALIDAVIT OF DISTI1BUTI0N 4 0 oa �µ r "CJ hereby declare that: Q Notice of Public Hearing • Notice of Public Meeting Q Board of Adjustment Agenda Packet • Board of Appeals Agenda Packet Planning Commission Agenda Packet Q Short Subdivision Agenda Packet [i Determination of Nonsignificance ❑ Mitigated Determination of Non - significance Determination of Significance and Scoping Notice O Notice of Action Q Official Notice • Notice of Application for Q Other Shoreline Management Permit Q Shorelinelnagement Permit [I Other was mailed to each of the following addresses on 5/2-2" /92. 198 S. ¢/3 AC.sO ? S. /ctiKcsr /so <<s %7RAFP(c 1 ) AUC. C, Mac b N Bozo Q4 S r 50. U-JA 998(0+, Uc Name of Project ,� �G t/i4W1' File Number p /C - 4 -8? Signature Mario A. Segale 18010 Southcenter Parkway Tukwila, WA 98188 David Parrot 5425 S. 178th Street Seattle, WA 98188 Schneider Homes, Inc. 6510 Southcenter Boulevard Suite #1 Tukwila, WA 98188 John W. Denure 5563 S. 178th ' Seattle, WA 98188 Paul Jonientz 5565 S. 178th Street Seattle, WA 98188 William M. Polk 2427 Financial Center Seattle, WA 98161 Roy E. Martin 5665 S. 178th St. Seattle, WA 98188 Robert Schoenbachler 15533 61st Avenue N.E. Bothell, WA 98011 Mario A. Segale P. 0. Box 88050 Tukwila, WA 98188 Herman Schoenbachler 18115 Southcenter Parkway Seattle, WA 98188 Ray and Madeline Flink 18059 Southcenter Parkway Seattle, WA 98188 WAC 197 -11 -970 DETERMINATION OF SIGNIFICANCE AND REQUEST FOR/COMMENTS ON,SCOPE OF EIS Description of Proposal Construct 144 unit apartment complex, recreation center and day- care /K -3 for 80 children. Requires Comprehensive Plan Amendment, Rezone, Conditional Use Permit and Planned Residential Development permits. Proponent PRIMARK CORP Location of Proposal, including street address, if any 18059 57th Avenue in NW a of Sec. 35, TWN 23, RGE 4, RGE 4; Tukwila, wa Lead Agency: City of Tukwila File No. EPIC-4-89 E'IS Required. The lead agency has determined this proposal is likely to have a significant adverse impact on the environment. An environmental impact statement (EIS) is required under RCW 43.21C.030(2)(c) and will be prepared. An environmental checklist or other materials indicating likely environmental impacts can be reviewed at our offices. The lead agency has identified the following areas for discussion-in the EIS: Earth, Water, Land Use, Transportation, Public Services and Utilities. Additional details and /or elements will be provided during detailed E.I.S. scoping. Scoping. Agencies, affected tribes, and members of the public are invited to comment on the scope of the EIS. You may comment on alternatives, mitigation measures, pro - bable significant adverse impacts, and licenses or other approvals that may be required. The method and deadline for giving us your comments is: All comments must be written. All comments must be received or post- marked by April 12, 1989. Responsible Official Rick Beeler Position /Title Planning Director Address 6200 Southcenter Boulevard Tu Phone 433 -1845 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 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 available with the City Clerk and Planning Department. City of Tukwila PLANNING DEPARTMENT 6200 Southcenter Boulevard Tukwila, Washington 98188 (206) 433 -1849 LETTER OF TRANSMITTAL TO -vi-7P7; Z>F Coco G Y) ADDRESS v/koAJMN74(... ATTENTION DATE -Y (_A9 REGARDING ell/C. - 4-8? WE ARE SENDING YOU THE. FOLLOWING 1346-ached Q Under separate cover COPIES DESCRIPTION 2 eV O A7ranc nF Sr GI cANC( THESE ARE TRANSMITTED T,AFF(C R ,IALYS7S Q For approval GC 0 Te-cry N i C A/VA c yceS Q For review and comment Ct TcKLfS [[ or your use and information X2.0 Se G'' "Aco' i f G S gx (I Q As requested COMMENTS ii /Lcb 3l2 r/B9//6L Q Other SIGNED (23 /P4.LTRANS) • MEMORANDUM From: Vernon Umetsuv x-1658 To: Environmental Reviewers RE: Sylvan Glen Apartments in the S.W. 1/4 of the 180th/Somthcemter Parkway Intersection. Date: March 20, 1989 I am distributing this preliminary list of environmental elements to be included is the project E.I.S. per direction from the DRC. I have drafted a list of specific items for discussion and included the full range of EIS items possible. I anticipate a limited scope EIS. Please submit your written comments by April 12th. This is a FIRM deadline. Comments not received by this date will not be included in the DEIS unless I am directed to do so by Rick Beeler. Elements of a limited scope environmental impact statement for Sylvan Glen apartment development. 1. NATURAL ENVIRONMENT A. Earth Complete geotechnical analysis per,submitted geotechnical study. Topographic map with existing and finished contour lines and sections. Provide existing slope map overlain on topographic contour map. Slope intervals to be 0-10%, 11-15%, 16-25%, 26-35%, B. Water Ground and surface water analysis. 2. BUILT ENVIRONMENT A. Land Use--Existing, Projected impacts on surrounding area from 178th/180th to City limits, and from I-5 to 57th Street. Discuss whether this will significantly affect the viability of Comprehensive Plan land use designations for adjacent properties. If viability is significantly degraded and more intensive use designations should be expected, discuss the capability of area utilities to support more intensive uses in this section. Consistency of proposed use and impacts with Comprehensive Plan land use policies and map, environmental (steep slope) policies, and Six Year Transportation Improvement Plan shall be shown. Please note that consistency with aigIILEct plan elements is required for Comprehensive Plan amendments. This would include, but not be limited to 188th/178th St. improvements. The Public Works Department should be contacted for determinations of consistency with road and utility plans. B. Transportation--Trip generation, travel pattern, and road capacity analysis per direction of the City Engineer. Consistency of development with Six Year Transportation Improvement Plan. Consult City Engineer for demonstrating proposed project has made provision for the So. 188th St./So. 178th St. improvements. • Consistency of internal circulation pattern with Fire Department and Public Works standards. C. Public Services and Utilities Sewer, Water,' Storm drainage. Connect points and system capacity. Storm drainage system capacity is especially limited in this area ' ' C'TTY OF TUKWILA 1)(5 ; Ss ®•l P,- c- one 3/r � CN CENTRAL PERMIT SYSTEM EPIC <1-- 8 FILE ENVIRONMENTAL REVIEW ROUTING FORM TO: [] BLDG 0 PLNG [] P.W. (j FIRE El POLICE (] P & R PROJECT S Y /A l C C tlTl LOCATION FGin/ /‘ PnI'LgZ 6>SG✓ or li02" S % 121 FILE NO. DATE TRANSMITTED ..3 //f //c41; RESPONSE REQUESTED BY 2720/g? STAFF COORDINATOR (/Ery).0voiv Mersu RESPONSE RECEIVED THE ATTACHED ENVIRONMENTAL CHECKLIST WAS RECEIVED REGARDING THIS PROJECT. PLEASE REVIEW AND COMMENT BELOW TO ADVISE THE RESPONSIBLE OFFICIAL REGARDING THE THRESHOLD DETERMINATION. THE ENVIRONMENTAL REVIEW FILE IS AVAILABLE IN THE PLANNING DEPART- MENT THROUGH THE ABOVE STAFF COORDINATOR. COMMENTS REGARDING THE PROJECT YOU WISH CARRIED TO THE PLANNING COMMISSION, BOARD OF ADJUSTMENT, AND CITY COUNCIL SHOULD BE MADE ON THE ATTACHED CENTRAL PERMIT SYSTEM ROUTING FORM. ITEM COMMENT A-PP -ictity r ACRcz7s ;V P<w c g,4 1 -l41.r •a lif;ec e_ 0 SW 4 OF 0 6 1 1 ' 9 ' + S 7 Z r , ,e e-A c;' C / (767-2-1S-77 rr 4 e_A./ es y -la % c:;k 0c it Ids •, df G_ / �2 �rCil ✓� CT s i� DATE fr//,/6///:r7 COMMENTS PREPARED BY C.P.S. Form 11 It5 cuSS ® b,QC one 3/r CITY OF TUKWILA CN CENTRAL PERMIT SYSTEM EPIC 4 - ‘8? FILE ENVIRONMENTAL REVIEW ROUTING FORM TO: EI BLDG El PLNG Q P.W. Q FIRE n POLICE n P & R PROJECT S YL(///J LOCATION Ft, //< P ccfZ 6).5634 or lg'O'244 -5 T'1 FILE NO. DATE TRANSMITTED -TA)" //8 RESPONSE REQUESTED BY 2/20/8? STAFF COORDINATOR (/E ' foN U,ci rsu RESPONSE RECEIVED THE ATTACHED ENVIRONMENTAL CHECKLIST WAS RECEIVED REGARDING THIS PROJECT. PLEASE REVIEW AND COMMENT BELOW TO ADVISE THE RESPONSIBLE OFFICIAL REGARDING THE THRESHOLD DETERMINATION. THE ENVIRONMENTAL REVIEW FILE IS AVAILABLE IN THE PLANNING DEPART- MENT THROUGH THE ABOVE STAFF COORDINATOR. COMMENTS REGARDING THE PROJECT YOU WISH CARRIED TO THE PLANNING COMMISSION, BOARD OF ADJUSTMENT, AND CITY COUNCIL SHOULD BE MADE ON THE ATTACHED CENTRAL PERMIT SYSTEM ROUTING FORM. ITEM COMMENT frPPcic,i j r Aces ;0 Pvk c i Sc-- , t g� ;� /'1 C (rL 0 Sc() i erff + S 7 1-21 r d icrA c c- ( 7 �' �` S%: ra 4 - � Z Gk/ o -cr- IF pd .s .S / rcPstz.- IS-5L3P) DATE � 1,31 COMMENTS PREPARED BY C.P.S. Form 11 YY■YYN 0\KC e 'I_SjUl.\ s V\ ere, iy101.4i VO 106 vrerfrk T vr) P \iPc b.7.‘ c reelS or s s SylVt.. _61e0, I 0o_v. de- 1-74/edo (or Kle.4,14.‘"..4 14.1 *Ar4ro: rt-e- S e c doe sly, .+1.041 pi- 12 tz. 0 c c�Ycs C\'\ Qt S rt_o volecior 4)01 ft) rep 5/frit... GI kifis_to 4 eit say.s +-Ak-e 1.INP) r 6 4r. (...m.N."11401" 64. ceckeisr-ett c_co"K.A.4- P7 +44- s 17 066 ?, 5,7„... c.c.., o Joocie.ok t.4„/I• Le Li FM/Y14. te,.4c kAsky oet15 e S U) (9--t-el.) V'A.1.,f Or-- C&OOlJ f& L / 25- aa Ici R7 TRANSPORTATION ANALYSIS FOR SYLVAN GLEN THE PROPOSED ACTION The proposal is to construct 144 residential units, 307 parking stalls, a school that is accredited for primary grades K -3, and licensed child- care for children, ages 4 weeks to 12 years. Total school enrollment will be 75 -80 children. The swimming pool and school facilities will be available to the greater Tukwila community, i.e. for swimming les- sons, youth theater, computer lessons, and summer sports camp. The location of the 542,123 s.f. 12.44 acre site is shown on the vicini- ty map in Figure 1. Access will be off of 57th Avenue South /Southcenter Parkway. An emergency secondary access will be provided off of South 178th /180th Street. The proposed site plan is shown in Figure 2. EXISTING CONDITIONS Study Area Transportation System The site is served by 57th Avenue South /Southcenter Parkway and South 178th /180th Street. Southcenter Parkway south of the site is a two lane road with a 60' right -of -way. According to the Tukwila Comprehen- sive Plan, Southcenter Parkway is a secondary arterial north of South 180th and a collector arterial south of 180th. There are no sidewalks south of South 180th on 57th Avenue South. According to the Comprehensive Plan, South 178th /180th is a collector arterial with a right -of -way of 60'. It presently has four lanes to the east and two lanes to the west of Southcenter Parkway /57th Avenue South. There are no sidewalks on this street. The grades on three legs of the intersection are relatively flat. The grade on South 178th Street within approximately 700' of the intersection is up to 21% downgrade.) In addition, there are two sharp curves within this section of roadway. This configuration has contributed to an accident hazard. 1 Information on percentage grades from Ross Earnst, Public Works Director, January 18, 1989. 1 Figure 1 Vicinity URBAN REGIONAL RESEARCH I000 1-o & 16 Seer q /o Sylvan Glen Submitted by Primark 3 tt su.ss. .4".. ISOM STICEer .6 4, ....roost. ...rt. VAILP VIGUAITY AMP Nom .r. • .ono 04. s Ma. 1.1wr as. •••••4 Ar MIK II... Figure 2 SITE PLAN t*-4r -r t . fYro oP tobrInoiTION. V4 we 1..4. • no, OINEMONEME MEM ffnurrrrir7--17--lik Izzat ■oEREWIff •-• • •,..• Sal -iLtiu.1■0•1 I_ • issim■Imommtmornamorinar. 11111••■11WIME,I=IIMIIINE •.4 IMMINNIMINIMINZIENNINIIDtl, 1111■111•■••••■•=91=1M1 Ikl1W-11.T.A.:4=1111■1111•11111111MMMIIV" 111-ffer_ at,"1". f:' all 1:13111O1= UTTRI=MMMSENNW 111}:CMIM @LCa0=1 OMMIIM■ =MC 1/11■M ED ELLEIICe F13 ■IMMEMMMi C16211 11111,,,C1Lat2==g1:11 There is an actuated traffic signal at the intersection of South 178th/ 180th and Southcenter Parkway /57th Avenue South controlling the various traffic movements. The Green River Valley Transportation Action Plan (GRVTAP) is a multi - jurisdictional implementing and financing plan for road improvement projects in the Green River Valley. Two projects in Tukwila are on the GRVTAP high priority list.2 There are three proposals for transporta- tion improvement projects in the immediate vicinity. The City of Tukwila has included these projects in their Six Year Transportation Improvement Program (TIP).3 TIP Priority #4: 57th Avenue South South 180th St. to south city limits (South 200th Street) Widen to 4 or 5 lanes Functional Classification: Class of Work: Work Code: Total Length in Miles: Funding Status: Expenditure Plan: Responsible Agency: Minor arterial New construction Grading Draining A.C. or PCC pavement Curbs or gutters .50 Carryover from previous year Proposed for funding 1st Year - $786,000 2nd Year - $613,000 City of Tukwila (according to GRVTAP) COMMENT: The City will be undertaking the design in the immediate future; however, they do not yet have construction funds. 2 PSCOG, January 1987, Green River Valley Transportation Action Plan. 3 Implementation of the Transportation Improvement Account Program, Report to the Legislative Transportation Committee, State of Washington Transportation Improvement Board, January 1989. 2 TIP Priority #50: South 188th Connector 4 South 178th Street - South 188th Street New 5 lane arterial Functional Classification: Class of Work: Work Code: Minor arterial New Construction Grading Draining AC or PCC Pavement Curbs and Gutters Total Length in Miles: .66 Funding Status: Unfunded Responsible Agency: WSCOT or USDOT COMMENT: According to interviews with members of the Tukwila Public Works Department, this project appears to be abandoned. See attached letter from Golder Associates regarding geotechnical problems with this alignment. TIP Priority #54: South 178th Street Southcenter Parkway - I -5 - South 178th Street New Interchange Functional Classification: Class of Work: Work Code: Minor arterial New Construction Grading Draining AC or PCC Pavement Curbs and Gutters Total Length in Miles: .46 Funding Status: Unfunded; funding unknown Responsible Agency: WSDOT (according to GRVTAP) 4 City of Tukwila, December 1984, South 188th Connector, I -5 at South 188th to South 180th St. by Centrac. 3 COMMENT: The Washington State Department of Transportation (WSDOT) is studying ways to reduce congestion on I -5 in the area from I -405 to Fife. Methods being evaluated focus on improvements or modifications to existing facilities, rather than on construction of a new interchange.5 The studies consider such options as the addition of High Occupancy Vehicle (HOV) lanes for both directions of traffic from I -405 to Fife and truck climbing lanes and transit only lanes from I -405 to the vicinity of South 200th. In addition, there is a special Federal Highway Administration study in this same general area of I -5 to test models on freeway congestion, weaving, ramp metering and other features to lower congestion. These FHWA studies will lead to proposed improve- ments or modifications (not new construction) as funds become available, e.g. through gas tax monies.6 Existing Traffic Volumes and Capacity According to traffic counts conducted by the City of Tukwila in 1989, the AWDT for the south leg of 57th Avenue South is 4,800 AWDT.7 The estimated P.M. peak is 550 vehicles. On South 178th, the AWDT is 12,500 with an estimated P.M. peak of 1,120 vehicles. Traffic volumes on other streets in the vicinity are shown on Figure 3. The term level of service (LOS) is used to describe roadway capacities. The categories of service range from the best, level A, to the worst, level F.8 The level of service at the intersection of South 178th/ 180th and 57th Avenue South /Southcenter Parkway is LOS C. On the south leg of Southcenter Parkway, it operates at LOS B. Level C is the 5 Washington State Department of Transportation, District #1, John Conrad, Planning Engineer, February 1989. 6 Ibid. 7 City of Tukwila, Public Works Department, 1988. 8 Techniques developed to access the levels of congestion that result from different street and volume conditions described in the Highway Capacity Manual, Transportation Research Board Special Report 209. 4 Figure 3 Existing Traffic Volumes Source: Tukwila Public Works Department URBAN REGIONAL RESEARCH Sylvan Glen Submitted by Primark design standard normally used to design city streets and roads. Safety 9 Over the period between January 1, 1986 and September 30, 1988, there were a total of 48 accidents on South 178th /180th, and Southcenter Parkway /57th Avenue South. Accidents occurred as follows: • 1986: 22 total; 6 injury accidents • 1987: 9 total; 1 injury accident • 1988: 17 total; 5 injury accidents As Figure 4 indicates, the majority of these accidents occurred at the intersection of South 180th and Southcenter Parkway (22 or 47% of the total). An additional 13 (28 %) were on South 178th where the majority hit the guardrail, the luminary pole, or a fence. Of the accidents on Southcenter Parkway north of South 180th Street, the majority of acci- dents occurred when entering or exiting a driveway. There were no fatal accidents, bicycle or pedestrian related accidents during the period. Transit Services, Pedestrian, and Bicycle Travel The area is served by three transit routes, all of which stop at the intersection of Southcenter Parkway and South 180th Street. Route 150 links the site with Auburn and downtown Seattle. Route 187 provides service to Federal Way. Route 155 is a connector with Valley General, Fairwood, and downtown Renton. There are no sidewalks or bicycle lanes in the immediate vicinity. IMPACTS Vehicular Transportation Generation Trip generation for the proposal was determined by applying the Insti- tute of Transportation Engineers (ITE) Trip Generation Report and its 9 Source: Accident Report Summaries from Washington State Patrol, January 1989. 5 G`i N Figure 4 Accidents Source: Washington State Patrol data from 1/1/85 to 9/30/88 URBAN REGIONAL RESEARCH Sylvan Glen Submitted by Primark subsequent updates to the proposed project. The project consists of 144 apartment units and a school licensed for childcare and accredited for primary grades K -3. Approximately half of the children (35) regularly enrolled in the school will be living in Sylvan Glen while the remaining 35 children will be from the greater community. The ITE generation rate of 6.1 trips per unit, plus an assumed 4.0 trips per child outside of the development have been used as the basis for projecting traffic generated by this project. Based on these generation factors, Table 1 shows the total estimated vehicle trips. TABLE 1 ESTIMATED VEHICLE TRIP GENERATION Daily Trips AM Peak Hour PM Peak Hour In Out In Out In Out 510 510 25 65 70 40 These generation factors result in 1,020 daily trips into and out of the project. It is estimated that approximately 25 vehicles will enter and 65 vehicles will exit during the morning peak hour. During the afternoon peak hour, it is estimated that 70 vehicles will enter and 40 will exit the proposed project. It is anticipated that the majority of this traffic will be to and from Southcenter Parkway. The proportions of this distribution may change somewhat when 57th Avenue South is improved to South 200th Street. At that point, there would be a direct connection to Orillia Road which may alleviate some pressure on South 178th. The projected trip distribution is shown on Figure 5. During the weekends when school is not in session, swimming and other lessons will be offered. Class size for these lessons have not been determined; however, total weekend trips are expected to be approximately the same as weekday trips. Total traffic volumes from the proposed action are added to existing 6 PROJECT GENERATION 90 ' (110) 1,020 1 Center Pkwy 25 285 N S. 180th St. r2-0 (20) (25) 140 285 60 710 30 (35) 31 57th Avenue South 000 AM Peak (000) PM Peak 0000 Average Weekday Traffic Volume (AWDT) NOTE: Roadways are not shown to correct scale. Figure 5 Project Trip Generation URBAN REGIONAL RESEARCH Sylvan Glen Submitted by Primark traffic volumes, plus a 3% annual growth rate to project the 1990 traffic as shown in Figure 6. Again, this estimate may somewhat under- state the traffic on 57th Avenue South once improvements have been made. The increase in traffic generated by this proposal is not expect- ed to change the existing level of service (LOS) on the streets and intersections within the immediate area. The bicycle and pedestrian increase from this development is estimated to be minor and will not impact the existing facilities. Parking It is anticipated that this proposal will not impact the existing parking facilities in the area since there will be 2 spaces per unit, plus 1.5 spaces per school employee, for a total of 307 parking spaces on site. This total will provide an adequate number of stalls for the residents, the school staff and the drop -in parents. Safety and Transit Since access to the project will be from 57th Avenue South, it is anticipated that the contribution to the accident rate will be less than the percentage increase in traffic. It is also anticipated that the City's improvement of 57th Avenue South will encourage people to use the South 200th /Orillia Road connection rather than South 178th Street. The accident rate is, therefore, expected to remain approxi- mately the same. Some increase in transit usage can be anticipated. 7 Figure 6 Estimated 1990 Traffic Volumes URBAN REGIONAL RESEARCH Sylvan Glen Submitted by Primark South 178th to the north. As part of our study, we reviewed construction records in the vicinity of the site to help identify potential geotechnically related construction problems. Our review revealed that a portion of the Interstate 5 (I -5) alignment located approximately two miles north of the Flink property site near Slade Way and South 53rd Avenue was excavated into an ancient landslide that was not identified prior to construction. This excavation caused unstable conditions that resulted in the development of 10 or 12 smaller landslides. Eventually this GOLDER ASSOCIATES, INC. • 4104.148TH AVENUE N.E., REDMOND (SEATTLE), WASHINGTON 98052, U.S.A. • TELEPHONE (206) 883.0777 • TELEX 5108002944 �, OFFICES IN CANADA • UNITED STATES • UNITED KINGDOM • AUSTRALIA February 21, 1989 2 893 -1005 hillside was stabilized using an extensive dewatering system, and large cylinder pile walls. Our geotechnical study of the Flink property found evidence of prehistoric landslide activity at the site which included steep landslide scarps, hummocky topography, fractured and intermixed soils and an anomalous closed drainage area just west of the site. Our opinion is based on a geologic reconnaissance of the site, interpretation of aerial photography covering the site, and excavation of 18 test pits to maximum depth of 14 feet. Based on the results of our preliminary study, we have not found any evidence to suggest the prehistoric landslides are currently unstable. In addition, we have not identified any geotechnical conditions that would make the site unsuitable for the proposed light weight structures and low volume roads within the Sylvan Glen project. However, we have identified several geotechnical concerns that require further investigation and specific design and construction considerations. Specifically these include the overall site stability, the stability of the steep landslide scarps, and foundation conditions on areas of suspected slide debris. Successful development of the site will require the project to be designed and constructed within several geotechnical constraints. One of the primary constraints affecting site development may be potential grading limitations in order to maintain site stability. This criteria could limit cuts and fills to less than about five feet to ten feet in critical areas. The alignments for Alternatives D and E extend across landslides that we have identified. Based on the existing site grades, we believe that construction of a four -lane road across the site would require cuts and fills of at least 30 feet in height within the landslide areas. In order to maintain site stability, it is possible that cut and fills of this magnitude may not be feasible in portions of the site without extensive mitigating measures. Mitigating measures could include installation of horizontal drains to stabilize the area, installation of deep soldier pile walls, and /or others. Although technically feasible, these solutions are expensive and may add substantial costs to the project. In general, the geotechnical concerns and potential constraints that we have identified with regards to the Sylvan Glen project will likely apply to the South 188th Connector project. Golder Associates February 21, 1989 3 893 -1005 We are available to discuss these comments and the results of our preliminary geotechnical study with yourself or any other interested parties. Sincerely, GOLDER ASSOCIATES INC. Rober . P m, Associate RLP /KH /jao1513 cc: Jane Preuss Golder Associates i' Golder Associates CONSULTING GEOTECHNICAL AND MINING ENGINEERS REPORT TO PRIMARK CORPORATION RESULTS OF THE PHASE I GEOTECHNICAL STUDY PROPOSED SYLVAN GLEN APARTMENTS TUKWILA, WASHINGTON Distribution: 2 copies Primark Corporation Seattle, Washington 2 copies - Urban Regional Research Seattle, Washington 5 copies Golder Associates Inc. Redmond (Seattle), Washington February 1989 893 -1005 GOLDER ASSOCIATES. INC. • 4104-148TH AVENUE N.E., REDMOND (SEATTLE), WASHINGTON 98052, U.S.A. • TELEPHONE (206) 883-0777 • TELEX 5106002944 OFFICES IN CANADA • UNITED STATES • UNITED KINGDOM • AUSTRALIA February 20, 1989 i 893 -1005 TABLE OF CONTENTS Page No. 1. PROPOSED PROJECT 2 2. SITE DESCRIPTION 2 3. REVIEW OF EXISTING INFORMATION 3 4. FIELD EXPLORATIONS 4 5. SUBSURFACE CONDITIONS 4 6. LANDSLIDE CONDITIONS 6 7. CONCLUSIONS AND RECOMMENDATIONS 7 8. USE OF THIS REPORT 8 LIST OF FIGURES 1. Vicinity Map 2. Site and Explorations Plan LIST OF APPENDICES APPENDIX A. Summary Test Pit Logs Golder Associates Golder Associates CONSULTING GEOTECHNICAL AND MINING ENGINEERS February 20, 1989 Our ref: 893 -1005 Primark Corporation 102 1200 South 192nd Street Seattle, Washington 98148 ATTENTION: Mr. Guv S. Spencer RE: RESULTS OF THE PHASE I GEOTECHNICAL STUDY PROPOSED SYLVAN GLEN APARTMENTS TUKWILA, WASHINGTON Dear Mr. Spencer: Golder Associates Inc. is pleased to present the results of our Phase I geotechnical study of the proposed Sylvan Glen Apartments. The site is located south of 180th Street and west if 57th Avenue South in Tukwila, Washington as shown in Figure 1. The purpose of this study was to evaluate the subsurface conditions at the site and to assess the suitability of the site for the proposed development. Our scope of work was described in a proposal to you dated April 14, 1988. We received your verbal authorization to proceed on January 10, 1989. The study described in this report consisted of 18 test pits excavated to a maximum depth of 14 feet, a geologic reconnaissance of the site, an interpretation of aerial photography covering the site, and a review of geotechnical reports and publications covering the site and adjacent properties. This study found evidence of prehistoric landslide activity at the site. This evidence includes steep scarps, hummocky topography, fractured and intermixed soils, and an anomalous closed drainage area just west of the site. The primary geotechnical concerns regarding the proposed development include: • The overall site stability. • The stability of the steep landslide scarps. • Foundation conditions on areas of suspected landslide debris. Based on the results of our preliminary study, we have not identified any geotechnical conditions that would make the site unsuitable for GOLDER ASSOCIATES, INC. • 4104-148TH AVENUE N.E., REDMOND (SEATTLE), WASHINGTON 98052, U.S.A. • TELEPHONE (206) 8830777 • TELEX 5106002944 OFFICES IN CANADA • UNITED STATES • UNITED KINGDOM • AUSTRALIA February 20, 1989 2 893 -1005 development provided our recommendations are properly implemented. Additional geotechnical data are necessary, however, in order to further evaluate the site slope stability concerns and to refine the general geotechnical recommendations included in this report. This additional work should include several borings, laboratory testing of the selected soil samples, a slope stability analysis, and preparation of additional geotechnical recommendations. The results of this study and our preliminary geotechnical recommendations are further described and discussed in the following sections. 1. PROPOSED PROJECT It is our understanding that the proposed development will consist of 20 two to three - story, wood - frame, slab -on -grade residential apartment buildings with accessory paved driveways and parking areas. We understand that buildings are to be placed on fill building pads and that the building foundation loads will be relatively light. It is also our understanding that the daycare facility, which will be located at the east end of the property, will include an eight -foot daylight basement. The proposed development will include some cuts and fills for the buildings, road construction, and construction of underground utilities. 2. SITE DESCRIPTION The site is an irregular shaped parcel consisting of approximately 12.44 acres. The site is located south of 180th Street and west of 57th Avenue South in Tukwila, Washington as shown in Figure 1. The site is currently accessible from a gravel drive off of South 180th. The driveway serves two woodframe, private homes and a fenced pasture in the eastern third of the site. Site slopes in the eastern third are relatively gentle with overall inclination on the order of 4H:1V to 10H:1V (horizontal to vertical). The majority of the western two - thirds of the site is undeveloped land forested with big leaf maples, alders, firs, blackberry bushes, and grasses. Slopes on the western two - thirds are steeper than in the eastern portion of the site and range between 1.5H:1V to 4H:1V. In the southwest portion of the site, the topography is slightly hummocky. The western portion is accessible from a series of rough, track roads and foot trails. This area of the site has several springs which contribute to a small stream and a wet area adjacent to the southwest and south central property boundaries respectively. This wet area was created when the current owner dammed the natural drainage outlet with a small two to three foot earthberm. At the time of our visit, the owner had recently removed the dam and was draining this area. A small basin on the adjacent property to the west, drains into the stream at the southwest property corner. The basin outlet had been previously dammed adjacent to the southwest property corner to create a water supply reservoir. Currently, a spring near the basin is cased to Golder Associates February 20, 1989 3 893 -1005 a depth of eight to ten feet and provides water for the houses on the property. It is our understanding that this well will be abandoned during project construction. 3. REVIEW OF EXISTING INFORMATION The site is located on the west slope of the Green River valley. In general, the area in the immediate vicinity of the site has been extensively developed including construction projects such as the construction of Interstate 5 (I -5) west of the site and the relocation of South 178th Street just to the north. As part of this study, we reviewed construction records and other existing information listed below. • Washington State Department of Transportation (WSDOT) Construction Records for I -5 and South 178th Street. • City of Tukwila Public Works Engineering Department information. • Sensitive Areas Map Folio for King County _,_W.ashi.notnn__no,„ —k„ 1987. L t.DSGIDe" • Aerial Photographs. SG4- We did not find any information indicating any 1 landslide problems on or adjacent to the site. 1 South 178th Street relocation construction recor; contacted the City of Tukwila Public Works Engin;___,�_ were informed that they are not aware of any stability problems near the site. The review of I -5 construction records did reveal that extensive landslides developed on the west slope of the Green River valley approximately two miles north of the site near Slade Way and South 53rd Ave. This area was identified as a large ancient landslide in which 10 to 12 smaller recent slides developed within the older slide debris. Some of these landslides were reactivated during the construction of I- 5. This hillside was eventually stabilized with large cylinder pile walls and an extensive dewatering system using temporary dewatering wells and permanent horizontal drains. The sensitive areas map compiled by King County identifies Landslide hazard areas in unincorporated King County. The landslide hazard areas are identified based on topography, stratigraphy, and relative permeability of these units. The site itself is not included in the King County Sensitive Areas Map (KCSAM). However, portions of the west slope of the Green River valley to the north and south of the site are located on the KCSAM and indicate that much of the western slope of the Green River valley is classified as a landslide hazard area. Golder Associates February 20, 1989 4 893 -1005 4. FIELD EXPLORATIONS As part of this study we excavated 18 test pits using a rubber -tired backhoe to depths of 10 to 13 feet and completed a geologic reconnaissance of the site. One shallow test pit was excavated using a hand shovel in an area the backhoe could not access. Test pit locations were determined by taping from existing landmarks. Elevations were interpolated from the topographic contours shown in Figure 2. The locations and elevations of the test pits should be considered approximate. The locations of the test pits are shown in Figure 2, and the test pit logs are present in Appendix A. The soils were classified in accordance with the Unified Soils Classification System which is also included in Appendix A. The test pits were excavated under the supervision of an engineer from our firm, who examined and retrieved disturbed, but representative, bulk samples of the soils encountered in the test pits. The soils encountered were classified and the pertinent information recorded, including soil sample depths, stratigraphy, soil engineering characteristics, and groundwater occurrence. All samples were sealed to prevent moisture loss, and returned to our laboratory for further examination. The stratification boundaries noted on the summary logs, represent the approximate boundaries between soil types. The soil and groundwater conditions are those recorded for the dates indicated, and may not necessarily represent those of other times or locations. 5. SUBSURFACE CONDITIONS The test pits encountered a wide variety of soil types. For the purpose of discussion, the site is divided into the east region, northwest region and slide debris region as described below. • EAST REGION: The east region includes the portion of the site east of the shaded area in Figure 2. The eastern half of this region encountered a thin layer of topsoil with upper loose sands underlain by silty sand and gravel at depth. In TP -3, 3.5 feet of fill was encountered. The present owner indicated that this portion of the property was slightly regraded with a combination of shallow cuts and fills. The western portion of this region encountered alluvium. • SLIDE DEBRIS REGION: This region includes the portion of the site that is suspected to be underlain by slide debris as is shown in Figure 2. Upper loose sands were encountered near surface at the higher elevations of this region, generally above elevation 80 to 90 feet. The upper loose sands appear to be underlain by disturbed, fractured and intermixed soils classified as slide debris at the eastern end of this region. Golder Associates considerable amount of heavily decayed logs and organic debris. The thickness of this layer ranged from four feet in TP -12 to more than eleven feet in TP -10. Golder Associates February 20, 1989 6 893 -1005 • TILL: An upper layer of till was encountered above the slide scarps in the northwest corner of the site. This soil typically consisted of dense, silty, fine to coarse sand, with little to some gravel. Where encountered, the till ranged from two to seven feet in thickness. • OUTWASH SAND: The explorations indicate that the till is underlain by outwash sand. The sand ranges in thickness from two to seven feet. The outwash sand typically consists of dense, brown and grey, sand with a trace of gravel. • HARD SILT AND CLAY: A very hard, dark grey, highly fractured and slickensided clay was encountered in TP -9 beneath the outwash sands. The thickness of this clay extended beyond the depth of the test pit. A two foot thick layer of hard, olive grey, massive silt was encountered in TP -8 within the outwash sand. Slight groundwater seepage was encountered at the eastern end of the site at a depth of 9 to 12 feet in TP -1, TP -2, and TP -3. Slight to moderate groundwater seepage was also encountered at various depths within the Alluvium. At a depth of eight feet, moderate groundwater seepage was encountered in the sand layer beneath the soft silt in TP- 13. No groundwater was encountered at an elevation greater than approximately 75 feet. At the time of our field investigation, the only spring observed was at the west end of the site which is currently being tapped as a domestic water supply. We were informed by the owner that one or more springs have occurred near TP -13 and apparently were a source of water for the pond that was once located in this area. 6. LANDSLIDE CONDITIONS We have identified past landslide activity at the west and northwest portion of the site that involves at least three separate landslides. Evidence for the prehistoric landslide activity includes: • Hummocky topography. • Steep scarps. • Poor drainage at the west end of the site. • Disturbed, fractured and intermixed soils. • Interpretation of aerial photographs. Immediately west of the site is a large bowl - shaped scarp. This scarp marks the top of at least one prehistoric landslide that deposited slide Golder Associates Golder Associates February 20, 1989 8 893 -1005 results of additional geotechnical information. These constraints will probably involve: • FOUNDATIONS: Generally spread footings will probably be acceptable. However, in the slide debris area and the lower site areas underlain by loose soils, special foundation preparation may be required. This would probably involve excavation of loose upper soils and placement of compacted fill. Locally some preloading may be appropriate. Although unlikely some areas within the slide debris region may require piles or relocation of structures. • GRADING LIMITATIONS: Our final recommendations will include specific criteria regarding allowable site grading including maximum allowable slopes, cuts, and fills. To maintain site stability, these criteria may be quite strict and could limit cuts /fills to less than about 6 to 10 feet in critical areas. • DRAINAGE PROVISIONS: A conservative approach to surface and subsurface drainage is essential at this site. These provisions will involve at least adequate control of surface runoff and placement of one or more interceptor drain trenches. • AREAS NOT TO BE DEVELOPED: We may identify selected areas which should not be developed due either to poor soil conditions or the potential for slide movement. • SLOPE OFFSET: We recommend that all buildings and structural walls be offset from the steep scarps. Depending on slope stability analyses, we anticipate slope offsets in the range of 10 to 20 feet. 8. USE OF THIS REPORT This report has been prepared exclusively for the use of the Primark Corporations and their consultants for the specific application to this project. Additional geotechnical exploration is required to assess suitability of the site for the proposed development. The preliminary field exploration has been performed in general accordance with locally accepted geotechnical engineering practice to provide information for the area explored. Variations in the subsurface soil and groundwater conditions between the actual test pit sites should be expected. Golder Associates February 20, 1989 9 893 -1005 If you have any question or need additional information, please contact us. Sincerely, GOLDER ASSOCIATES INC. Kenneth Haskell Project Engineer Ro,ert . 1u Associate RLP /CL /KH /jao1509 Golder Associates FIGURES Golder Associates Reference: Thomas Brothers Map, 1988. PROJECT NO 893 -1005 DWG. NO 9690 DATE 2/20/89 DRAWN 'CW APPROVED KH FIGURE 1 VICINITY MAP PRIMARK/ SYLVAN GLEN /TUKWILA Golder Associates Inc. 22O N 0 CD (0 °� 1 Existing Residence 80 0 0 h a. 0 50 N 1 100 200 HD -1! :ATP -15, 15 110 0 0 LEGEND 90 *TP -1 Test Pit Location IS HD -1 Hand Dug Test Pit Suspected Area Underlain by Prehistoric Slide Debris 100 Contour Interval (feet) r2o Trir Existing Slide Scarp FEET FIGURE 2 SITE AND EXPLORATION PLAN PRIMARK/ SYLVAN GLEN / TUKWILA •��� AAOJECYNO.'1593 1OO5 DWG NO 9679 DATE 2 /20/ 89 DRAWN CW APPROVED KH Golder Associates Inc. APPENDIX A Golder Associates Unified Soil Classification System Criteria for Assigning Gro ip Symbols and Names Soil Classificot;on Generalized Group Descriptions COARSE — GRAINED SOILS More than 50% retained on No. 200 sieve GRAVELS more than 502 of coarse froction . retained on No. 4 Sieve CLEAN GRAVELS Less than 52 fines GW well—graded Grose!' GP Poorly— groded grovels GRAVELS %Vat! FILES More than 122 lines CIA Grovel and Silt Mixtures GC Crcve! and Cloy Mixtures SANDS 502 or more of coarse fraction passes No. • Sieve CLEAN SANDS Less than 52 fines SW Well— graded Sands SP Poorty— graded Sands SANDS WITH FINES More than 122 fines SM Sond and Sat Mixtures SC Sond and Clay Mixtures ANE— GRAINED 501L5 502 or more posses the No. 200 sieve SILTS AND CLAYS Liquid limit less than 50 INORGANIC CL tow— plasticity Clays ML Non— plastre and Low — Plasticity Silts ORGANIC 01 Non — plastic and Low— Plasticity Organic Cloys Non — plastic and Low — Plasticity Organic Silts SILTS AND CLAYS Liquid limit greater than 50 INORGANIC CH High— plasticity Cloys UPI High— plasticity Silts ORGANIC OH High — plasticity Organic Clays High — plasticity Organic Silts HIGHLY ORGANIC SOILS Primarily organic matter. dark in color, and organic odor PT Peot Relative Density or Consistency Utilizing Standard Penetration Test Values Soils (a) (b) Cohesive Soils ) Density (c) N (c) , blows /ft. Relative Density n 'Consistency (c) N. blows /ft. Undroined (d) Shea Strength (psf) Very loose Loose Compact Dense Very Dense 0 to 4 4 to 10 10 to 30 30 to 50 over 50 0 - 15 15 — 35 35 — 65 65 — 85 >85 Very soft Soft Firm Stiff Very Stiff Hard 0 to 2 2 to 4 4 to B 8 to 15 15 to 30 over 30 C250 250 -500 500-1000 1000-2000 2000 -4000 >4000 (a) Soils cons sting of gravel. sand. and silt. either separately or in combination. possessing no characteristics of plastic; y. and exhibiting drained behavior. (b) Soils possessing the ct arocteristics of plasticity. and exhibiting undrained behavior. (c) Refer to text of ASTM 0 1586 -84 for o definition of N; in normally consolidated cohesionless soils Relative Density terms are based on N values corrected for overburden pressures. (d) Undrained shear strength w 1/2 unconfined compression strength. Descriptive Terminology Denoting Component Proportions Descriptive Terms Range of Proportion Trace Above 12 in. 0 -52 Little Grovel 5 -122 Some fo or Adject;m ) 12 -302 And Sand 30 -502 (o) Use Gravelly, Scndy or Sitty as appropriate. Component Definitions by Gradation Component Size Range Boulders Above 12 in. Cobbles 3 in. to 12 :n. Grovel 3 in. to No. • (4.76mm) Coarse grovel 3 in. to 3;4 in. Fine grove: 314 ;n. to No. • (4.76mm) Sand No. 4 (4.76mm) to No. 200 (0.074m •' Coarse sand No. 4 (4.76mm) to No. 10 (2.3mm.) Medium so -.d No. 13 (2.0•m) to No. •0 (0.42mm) Fine sand No. 40 (0.42mm) to No. 200'(0.074 -' ^.; Slt ana Clcy Smaller than No. 200 (0.07•mm) Samples SS SPT Sampler (2.0- OD) HD Heavy Duty Split Spoon SH Shelby Tube P Pitcher Sampler 8 Bulk C Cored Unless otherwise noted. drive samples advanced with 140 Ib. hammer with 30 in. drop. Laboratory Tests Test Designation Moisture (1) Density 0 Groin Sire G Hydrometer H Atterberg Limits (1) Consolidation C Unconfined U UU Triox UU CU Trio: CU. CO Trios CO Permeability, P (1) Moisture and Atterberg Limits plotted en log. Silt and Clay Descriptions Description Typical Unified Designation Slat ML (non — plastic) Clayey Silt CL —ML (low plasticity) Sny Cloy CL Clay Cn Ptastic Silt Mrs Orgcnic Soils CL. OH. Pt 73 - 1064 /FOPM 5'3 SOIL CLASSIFICATION /LEGEND t«\ j; Golder Associates TEST PIT LOG TP -1 Approximate Surface Elevation: 62 ft. 0.0 to 0.5 ft. Very loose, dark brown, silty SAND, trace gravel, roots and organics (SM) (TOPSOIL) 0.5 to 8.0 ft. Loose, brown olive grey, clean, fine to coarse SAND, trace gravel, occasional cobbles. (SP) Compact at 4.0 ft. Compact to dense at 7.0 ft. 8.0 to 10.0 ft. Compact, greyish- brown, silty, fine to coarse SAND, some gravel. (SM) 10.0 to 12.0 ft. Compact, greyish- brown, clayey fine to coarse SAND, little to some gravel. Mottled with iron stains. (SC) Grades to a sandy clay at 11 ft. 12.0 to 13.0 ft. Compact, olive grey and brown, gravelly SAND, little silt with occasional dark rust colored zones. (SW) Coarsens with depth. Occasional cobbles at 13.0 ft. Slight groundwater seepage encountered at 10.5 ft. Seepage increases at 13.0 ft. Test pit caving at 13.0 feet. Test pit terminated at depth of 13.0 ft. 1/19/89. Golder Associates TP -2 Approximate Surface Elevation: 55 ft. 0.0 to 0.25 ft. Very loose, dark brown, fine to coarse SAND, little to some silt gravel, roots and organics (SM) (TOPSOIL) 0.25 to 4.5 ft. Loose, light brown, clean, fine to coarse SAND, (SP) Compact at 3.0 ft. 4.5 to 6.5 ft. Compact, grey and rusty brown, gravelly, fine to coarse SAND, with occasional 2 to 3 -inch diameter clasts of hard, brown silt. (SP) 6.5 to 8.5 ft. 8.5 to 9.0 ft. TP -3 Compact, light brown and grey, clean, fine to coarse SAND. (SP) Compact, grey and rusty brown, gravelly, fine to coarse SAND, little to some silt and clay. (SW -SC) Very Slight groundwater seepage encountered at 9.0 ft. Upper five feet of test pit caving. Test pit terminated at depth of 9.0 ft. 1/19/89. Approximate Surface Elevation: 66 ft. 0.0 to 3.5 ft. Very loose, intermixed light and dark brown, fine to coarse SAND, little to some silt, roots and organics with bricks and boards (SM) (FILL) 3.5 to 10.0 ft. Loose, olive grey, gravelly, fine to coarse SAND, little to some clay. (SW -SC) Compact at 6 ft. Clay content increasing with depth. 10.0 to 12.0 ft. Compact, grey and rusty brown, gravelly, fine to coarse SAND, little to some clay, occasional cobbles. (SW -SC) Very slight groundwater seepage encountered at 12.0 ft. Test pit terminated at depth of 13.0 ft. 1/19/89. Golder Associates TP -4 Approximate Surface Elevation: 85 ft. 0.0 to 0.25 ft. Very loose, dark brown, silty, fine to coarse SAND, roots and organics (SM) (TOPSOIL) 0.25 to 3.5 ft. Loose, light brown to grey, clayey, fine to coarse SAND, some gravel, occasionally mottled with iron stains. (SW -SC) 3.5 to 13 ft. Loose, medium brown, clean, fine to coarse SAND, trace gravel, occasional cobbles. (SP) Compact at 5.0 ft. Becomes dense and interlayered with grey medium to coarse sand at 7.0 ft No groundwater encountered. Test pit caving at 13.0 ft. Test pit terminated at depth of 13.0 ft. 1/19/89. TP -5 Approximate Surface Elevation: 95 ft. 0.0 to 0.25 ft. Very loose, dark brown, silty, fine to coarse SAND, roots and organics (SM) (TOPSOIL) 0.25 to 5.0 ft. Loose, brownish olive grey, fine to coarse SAND, with . some yellowish iron staining. (SP) 5.0 to 10.0 ft. Compact, light olive grey, clean, fine to coarse SAND, trace gravel with occasional cobbles (SP) No groundwater encountered. Test pit caving at 8.0 ft. Test pit terminated at depth of 10.0 ft. 1/19/89. Golder Associates. TP -6 Approximate Surface Elevation: 104 ft. 0.0 to 0.25 ft. Very loose, dark brown, silty, fine to coarse SAND, roots and organics (SM) (TOPSOIL) 0.25 to 3.0 ft. Very loose, rusty dark brown, silty, fine to coarse SAND, little to some gravel with occasional cobbles, some roots and organics. (SM) 3.0 to 4.0 ft. Loose, light olive grey,silty, fine to coarse SAND, little gravel. (SW -SM) 4.0 to 6.0 ft. Compact, brownish olive grey, fine to coarse SAND. (SM) 6.0 to 9.0 ft. Compact, brownish olive grey, fine to coarse SAND, some gravel, little silt, with occasional cobbles (SM). 9.0 to 13.0 ft. Loose to compact, light brown to olive grey, clean, fine to coarse SAND, trace gravel. (SP) No groundwater encountered. Test pit caving at 13.0 ft. Test pit terminated at depth of 13.0 ft. 1/19/89. TP -7 Approximate Surface Elevation: 156 ft. 0.0 to 0.5 ft. Very loose, dark brown, silty, fine to coarse SAND, roots and organics (SM) (TOPSOIL) 0.5 to 1.0 ft. Loose, brown, silty, fine to coarse SAND, little gravel. (SM) 1.0 to 7.0 ft. Dense, brown and olive grey, silty, fine to coarse SAND, some gravel, mottled with iron stains (GLACIAL TILL) (SM -SW) 7.0 to 10.0 ft Compact to dense, olive grey, clean fine to coarse SAND, trace gravel. (SP) No groundwater encountered. Test pit terminated at depth of 10.0 ft. 1/19/89. Golder Associates TP -8 Approximate Surface Elevation: 156 ft. 0.0 to 0.25 ft. Very loose, dark brown, silty, fine to coarse SAND, roots and organics (SM) (TOPSOIL) 0.25 to 2.0 ft. Loose, brown, silty, fine to coarse SAND, trace gravel with occasional cobbles. (SM) 2.0 to 4.0 ft. Dense, brown and olive grey, silty, fine to coarse SAND, some gravel, mottled with iron stains (GLACIAL TILL) (SM -SW) 4.0 to 7.0 ft Compact, dark olive grey, clean fine to coarse SAND, trace gravel. (SP) 7.0 to 9.0 ft. Hard, olive grey, SILT, trace to little fine sand, massively bedded. (ML) 9.0 to 11.0 ft. Dense, olive grey, fine to coarse SAND, little gravel, trace silt. (SW) No groundwater encountered. Test pit terminated at depth of 11.0 ft. 1/19/89. TP -9 Approximate Surface Elevation: 195 ft. 0.0 to 0.25 ft. Very loose, dark brown, silty, fine to coarse SAND, roots and organics (SM) (TOPSOIL) 0.25 to 7.5 ft. Dense, grey and brown, silty, fine to coarse SAND, little gravel, mottled with iron staining. (SM) (GLACIAL TILL) 7.5 to 8.5 ft. Dense, grey and brown, clean, fine to coarse SAND. (SP). 8.5 to 9.0 ft Very hard, dark grey, clay, heavily fractured with slickensides, occasional thin contorted layers (less than 1 mm) of light brown, fine to medium sand. (CL) Two large boulders encountered at 9.0 ft. No groundwater encountered. Test pit terminated at depth of 9.0 ft. 1/19/89. Golder Associates Approximate Surface Elevation: 65 ft. 0.0 to 1.0 ft. Very loose, dark brown, clayey, fine to coarse SAND, little gravel, very moist, roots and organics (SC) (TOPSOIL) 1.0 to 12.0 ft. Compact to dense, greenish dark grey, clean, fine to coarse SAND with slightly decayed log fragments (SP). (ALLUVIUM) Becomes gravelly with occasional boulders and cobbles from 5.0 to 7.0 ft. Very slight groundwater seepage encountered at 10 to 12 feet. Test pit terminated at depth of 12.0 ft. 1/20/89. TP -11 Approximate Surface Elevation: 68 ft. 0.0 to 1.0 ft. Very loose, dark brown, silty, fine to coarse SAND, trace gravel, very moist, roots and organics (SM) (TOPSOIL) 1.0 to 2.0 ft. Loose, dark olive grey, fine to coarse SAND, little silt, trace gravel, some roots. Boulder at 2.0 ft.(SP) 2.0 to 6.0 ft. Loose to compact, intermixed brown, clayey fine to coarse SAND, little gravel; light grey SILT; and dark grey fine SAND, grey, mottled with iron stains, occasional log fragments. (SM -SC) Compact at 4.0 ft. 6.0 to 10.0 ft. Compact, intermixed brown, fine to coarse SAND, little to some gravel, light grey SILT; and occasional till clasts one half -inch in diameter, mottled. (SM) 10.0 to 12.0 ft. Compact, brownish olive grey, silty, fine to coarse SAND, little gravel. (SP) No groundwater encountered. Test pit terminated at depth of 12.0 ft. 1/20/89. Golder Associates TP -12 Approximate Surface Elevation: 77 ft. 0.0 to 1.0 ft. Very loose, dark brown, silty, fine to coarse SAND, roots and organics (SM) (TOPSOIL) 1.0 to 5.0 ft. Compact, greenish grey, fine to coarse SAND, little silt, little gravel with occasional log fragments. (SP) 5.0 to 10.0 ft. Firm, brownish olive grey, SILT, trace gravel, occasional fractures, mottled with iron stains, and interlayered with occasional medium grey, medium to coarse sand. (ML) Moderate groundwater seepage encountered from 1.0 to 5.0 ft. Test pit terminated at depth of 10.0 ft. 1/20/89. TP -13 Approximate Surface Elevation: 80 ft. 0.0 to.0.5 ft. Very loose, dark brown, silty, fine to coarse SAND, roots and organics (SM) (TOPSOIL) 0.5 to 8.0 ft. Firm, brownish -olive grey, SILT, trace fine sand, heavily fractured, mottled with iron stains. (ML) 8.0 to 10.0 ft. Compact, brownish olive grey, fine to coarse SAND, trace silt. (SP) Moderate groundwater seepage encountered at 8.0 ft. Test pit terminated at depth of 10.0 ft. 1/20/89. Golder Associates TP -14 Approximate Surface Elevation: 72 ft. 0.0 to 1.0 ft. 1.0 to 6.0 ft. Very loose, dark brown, silty, fine to coarse SAND, roots and organics (SM) (TOPSOIL) Loose to compact, greenish grey, clean, fine to coarse SAND, with heavily decayed wood and organic debris, horizontally layered (up to 1.0 ft thick). Moderate groundwater seepage observed from the decayed material. (SP) 6.0 to 11.0 ft. Soft, light, brownish olive grey, SILT, little to some sand with some hard clay clasts, mottled with iron stains. (ML -SM) Firm at 8.0 ft. Moderate groundwater seepage encountered from 1.0 to 5.0 ft. Test pit terminated at depth of 11.0 ft.. 1/20/89. TP -15 Approximate Surface Elevation: 88 ft. 0.0 to 1.0 ft. Very loose, dark brown, fine to coarse SAND, little to some silt, trace gravel, occasional cobbles, with roots and organics (SM) (TOPSOIL) 1.0 to 10.0 ft. Compact, brownish olive grey, fine to coarse SAND, trace gravel, moist, mottled with iron stains. Test pit caving at 6.0 ft. No groundwater seepage encountered. Test pit terminated at depth of 6.0 ft. 1/20/89. Golder Associates TP -16 Approximate Surface Elevation: 136 ft. 0.0 to 1.0 ft. Very loose, dark brown, fine to coarse SAND, little . to some silt, trace gravel, occasional cobble, roots and organics (SM) (TOPSOIL) 1.0 to 12.0 ft. Loose, brown to light olive grey, fine to coarse SAND, occasional decayed log fragments, slightly moist. Compact at 5.0 to 6.0 ft. No groundwater seepage encountered. Test pit collapsed at 12.0 ft. Test pit terminated at depth of 12.0 ft. 1/20/89. TP -17 Approximate Surface Elevation: 150 ft. 0.0 to 0.5 ft. Very loose, dark brown, silty, fine to coarse SAND, trace gravel, roots and organics (SM) (TOPSOIL) 0.5 to 8.0 ft. Loose, medium brown, silty, fine to coarse SAND, trace to little gravel with occasional cobbles and boulders, occasional decayed wood fragments, slightly mottled with iron staining. Compact at 5.0 ft. 8.0 to 11.5 ft. Compact to dense, medium brown, gravelly SAND, occasional cobbles. No groundwater seepage encountered. Test pit terminated at depth of 11.5 ft. 1/20/89. Golder Associates TP -18 Approximate Surface Elevation: 155 ft. 0.0 to 0.5 ft. Very loose, dark brown, fine to coarse SAND, little silt, trace gravel, roots and organics (SM) (TOPSOIL) 0.5 to 8.0 ft. Loose, medium brown, fine to coarse SAND, little to some gravel, trace silt, occasional clasts of dense, brownish olive grey, fine to coarse SAND. Compact at 6.0 ft. 8.0 to 10.0 ft. Compact, brownish olive grey, clean, fine to coarse SAND with occasional clasts of dense sand. 10.0 to 11.0 ft. Compact to dense, reddish brown to olive grey, fine to coarse SAND, some gravel, little silt. No groundwater seepage encountered. Test pit terminated at depth of 11.0 ft. 1/20/89. HD -1 (Hand dug test pit) Approximate Surface Elevation: 0.0 to 0.25 ft. Very loose, dark brown, fine to coarse SAND, little silt, trace to little gravel, roots and organics (SM) (TOPSOIL) 0.25 to 2.0 ft. Loose, dark brown and dark olive grey, fine to coarse SAND, trace to little gravel, trace silt some roots and organics. Color changing to a light brownish olive grey with depth. KH /jao1510 Test pit terminated at 2.0 ft. 1/20/89. Golder Associates • ENVIRONMENTAL CHECKLIST A. BACKGROUND 1. Name of proposed project, if applicable: 2. Name of applicant: Primark Control No. Epi ^file No. �--g5' Feei00.00 Receipt No. 7?.3 S Sylvan Glen 3. Address and phone number of applicant and contact person: 1200 South 192nd St., Suite 102, Seattle, WA 98148. Phone: 241 -6241 (Contact Person: Jane Preuss, 624 - 1669) 4. Date checklist prepared: February 15, 1989 5. Agency requesting Checklist: City of Tukwila 6. Proposed timing or schedule (including phasing, if applicable): Construction. spring 199n 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. None 9. Do you know whether applications are pending for governmental approvals of other proposals directly affecting the property covered by your proposal? If yes, explain. No 10. List any government dprovals or permits that will be• needed for your proposal. • • f • use for school_ 11. Give brief, complete description of your proposal, including the proposed use and the size of the project and site. There are several questions later in thi checklist that ask you to describe certain aspects of your proposal. You do no need to repeat those answers on this page. Section E requires a complete description of the objectives and alternatives of your proposal and should not be summarized here. Construction of 144 roidential units: ayrarp rent_e lirpnspd fnr aporoximatJ y75 or 60 children, a recreation renter with regulation size swimming pool jl 307 parking spares 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 applica- tions related to this checklist. The 12.445 -acre site is hounded on the north. by 172th a ast—by S.E. 57th. The legal description is (see attached sheets), A topographic map was submit tEd_as_aart eLthe pre lictioa_.package_ 13. Does the proposal lie within an area designated on the City's Comprehensive Land Use Policy Plan Map as environmentally sensitive? No. -3- 1 11/18/88 15 ! 04 $206 246 8154 PR I MARK 002 • /_ EG4L Dt 5CR/PT /ON Thal portion io/i of the SC %? of the NW /a of Sec. 35, T. 23 N., R. 4 E_, w. M. Kin, County, Washington, described os Jo / lows: Be9inniny on the southerly /ine of said Subdivision of o point 657.0? feet west- erly a1 the /Itcrsec /ion of .soid southerly /•ne with rnC wester /y tine 4/ CDunry /Food I/o. 54 0 t S •1 TM Ave. 5. ), said point being the soatnwegterty corner of that Certain rroct of /and described in instru- ment recorded under RcCOrdinq No. 4744487; Thence N. /6 °P /'00''E., 6'3 /.,JJ feel to the northwesterly corner of sold Curtain tract of fond; Thence 5.447'S3'lo'E., sem.8O feet; Thence N. 6O°47'.3O'E., eO6.43 feet to ttie westerly fine of said County f r Rood; Thence nor /het /y along soid wester /y dQfine extended ?or /heriy to the northerly It\ � /ine of sold subdivision; Thence wesherCAP. along said northerly fine to the northwest j corner of said subdivision; Thence southerly Wong the wester /y h»e thereof to the south - west corner of soid subdivision; Thence easterly o /ong the souther /y like thereof to p j the Point of Beginning; TOGETHER WITH 4 - o• that portion 0/ S. 178 TN 5 . vocoted by City use of 7jMui /o Ordinance No. 5'66, 4s would `,•' .i2 attach by operotion of /ow. ' EXCEPT that portion thereof Aescridcd „• a� os follows: 8eginnin9 of the northwest corner of S4id Subdivision; rhe„ce 5.8765I101°C. Wong the North line of sold sub- division, BOLO feet to the True Point of 5e9inn /i,g ; Thence South, perpehdicu /or to the sold North tine of of said .5vbd;vi.s or,, e50 feet; Thence rvyt, parallel with /he sold NU t/ line of sole/ subdivision to //,c Weal fine of County Rood No.540; Thence northerly o %ong the said Wester /y • tine of soid Coll nf9 Rood, G -e/endcc/ /iur / /icr /y, to the ,r, /ars-ectip,, with the solo NCrtfh /ine of said subdivision; Thence N.87 °.5 /'0/''W. u/ony soid North fine of .said se' bd 'WV ivn, ,335 feet. more or /eSS, to the True Point of 1:3e9inninq. Ar,c/ £'AcePT 'hot par /ion thcrea/ hying souther/9 of o line described os follows : .e Southwest corner of >he 5E1/4 of t/? ' NPV'/4 of said .5cction 35; Thence N. /•49'45'e. olon9 of _4e -i .S/JbP / /L/ % 4- 4"g_9t s -1■ , .... tile .. .•! cnirl /.ne. • 7•1-...n�w - - - ..._......... •....,.,‘.,.y wv,.y .�ora euesreriy �� A48 7°4e ,T .w i � , line ez tended northerly to the northerly .334.09' • , i I 1 line of said subdivision; Thence ;!,ester /y Yra+Mcf cw trNE) SET REBQR d CAP ..e-.5. ro7o8" ILI 1 along Said northerly line f.2`the northwest -J ! corner of said subdivision; Thence southerly + - along the westerly /;re- thereof to the south- I ; west corner of said subdivision; Thence t. 01 D / 1 easterly o/on9 the southerly /foe thereof to .0 o the Pc.n1 -cf Be9inninq; rOGETHER WITH x'09.*, _ 3 3o' �� ? that portion of S. /78 TN St. vacated by City. °cp-cS,_ r'- ; of Tukwila Ordinance No. SC6, a5 would • rep' attach by operation of /ou.. JOE) 2- • r! / EXCEPT thol portion thereof described ,t v. 145" Z�� ' 4 as follows: ( .114 �E'RJ 4 Beginning 0/ me northwest corner of Said subdivision; woo,ta.. .,.. Of IZ 1 Thence -5.87°37'01°E. olong the North line of sold -sub- -" � O �� ,� division, 800 feel to the 7"rue Point of Beginning two. . NPV I Y45 ; 34 ' Thence South, perpendicular to the sold North line of / o� of sold subdivision, 250feet; Thence Fos.', parallel f f �1 with the sold /North /ire of said subdivision to the e- • 4 J-- • + West line of County Road No_ 540; Thence northerly + o/ony the sofa Westerly tine of sorb' County Rood, ci extended northerly, to the intersection with the said North /ine of said subdivision; Thence N.87 °5 /'0/.1 o/onq sold North line of ,;aid subdivision, 335 feet, more or less, to the True Point of Beginning. Arid EXCEPT that portion thereof Iying souther /y of .0 / Dc described os Deginn ;n9 of she Southwest corner of the 3E 4 of the NW 1/4 of sold Section 35; Thence N. t °49'45'E. olon9 the Wes, line of sold subdivision, SG 5_20 feet to the True Point of Beginning of sold line; Thence N. C3°J6'QS'E., 48s 45 feet to on iron pipe t .'he northwesterly Corner of shot certain tract of /ond in sold subdivision described in +nsrrarrent recorded under l?ecordrog No. 417444 87; Thence 5.87 °54'30 "E_, 504.80feet; Thence N. 60 °4T'9O E., 206:43 feet to the Westerly margin o1 County Road /i/o.340 (3-7r"' Ave_ 5.1 and the terminus of sold line. ALSO EXCEPT /hot portion 19ing wt-min the right- of -way of S_ /78 "I St_ as presently estob /ished- NOT£= Above- /ego/ description Jrorn Schedule A, Chicago Title f,?suronce Corrpong s No. 130944 SURVEYORS CFPT/$I(' 7 TO BE COMPLETED BY APPLICANT B. ENVIRONMENTAL ELEMENTS 1. Earth a. General description of ite (circle one): Flat, rolling, hiller, steep slopes mountainous, other b. What is the steepest slope on the site (approximate percent slope)? •40% and over 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. Information will be provided in soils report to • be prepared by geotechnical engineer. d.. Are there surface indications or history of unstable soils in the immediate vicinity? If so, describe. No. • e. Describe the purpose, type, and approximate quanti- ties of any filling or grading proposed. Indicate source of fill. To be discussed in the soil report tg_be submitted under separate cover. f.• Could erosion occur as a result of clearing, construction, or use? If so, generally describe. Measures dictated by the soils engineer will be taken to minimize erosion. g. About what percent of the site will be covered with impervious surfaces after project construction (for example, asphalt or buildings)? Approximately 203.900 s.f. of impervious surface is proposed, which is 3R_5° of the total city Evaluation for Agency Use Only • Evaluation for 41, Agency Use Only h. Proposed measures to reduce or control erosion, or other impacts to the earth, if any: Pleasures will be defined in forthcoming soils report. 2. Air a. What types of emissions to the air would result from 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. During construction. dust will be created. Therew will be some long -term impacts created by increased traffic and particulate matter from the fireplaus. Oua►itities will not be significant. 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: None prnpnced 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. Thp GEpan River is 1/4 mile frorl-the- site. --_ • 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. No 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. NA 4) Will the proposal require surface water withdrawals or diversions? Give general description, purpose, and approximate quan- tities, if known. No. 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. Evaluation for Agency Use Only Evaluation for +, 010 Agency Use Only b. Ground: 1) Will ground water be withdrawn, or will water be discharged to ground water? Give general description, purpose, and approximate quan- tities, if known. No. 2) Describe waste materials that will be discharged into the ground from septic tanks or other sour- ces, 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. NA 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. An on -site stormwater detention system will be designed in relation to the building groupings. The system will be designed by a licensed civil engineer and submitted as part of permit ap- plication drawings. Evaluation for Agency Use Only 2) Could waste materials enter ground or surface waters? If so, generally describe. No d. Proposed measures to reduce or control surface, ground, and runoff water impacts, if any: Measures to reduce and control surface and runoff water impacts wi a designed by a licensed civil engineer. 4. Plants .a. Check or circle types of vegetation found on the site:. X deciduous tree: alder, maple, aspen, other evergreen tree: fir, cedar, pine, other X shrubs grass _ pasture _ crop or grain wet soil plants: cattail, buttercup, bullrush, skunk cabbage, other water plants: water lily, eelgrass, milfoil, other X_ other types of vegetation b. What kind and amount of vegetation will be removed or altered? The majority of the major stands _pf trees are located on the steep _portions of the sitei they will not be disturbed. VegetdtiQn will he disturbed in areas requiring grading for the roads and buildings, c. List threatened or endangered species known to be on or near the site. None known •d. Proposed landscp n g, use of nativ e plants, IP or other measures to preserve or enhance vegetation on the site, if any: A proposed list of plantings will be submitted by the landscape architect_ 5. Animals a. Circle any birds and animals which have been observed on or near the site or are known to be on or near the site: birds: heron, eagle, songbirds other: mammals: deer, bear, elk, beaver, other: squirrels fish: bass, salmon, trout, herring, shellfish, other: NA b. List any threatened or endangered species known to be on or near the site. NA c. Is the site part of a migration route? If so, explain. Part of the Puget SoundLWest Coast fl„ywj for various species of migratory birds. d. Proposed measures to preserve or enhance wildlife, if any: None propp e Evaluation for Agency Use Only Evaluation for 40 Agency Use Only 6. Energy and Natural Resources a. What kinds of energy (electric, natural gas, oil, wood stove, solor) will be used to meet the completed project's energy needs? Describe whether it will be used for heating, manufacturing, etc. Electric energy will be used for all systems_ b. Would your project affect the potential use of solar energy by adjacent properties? If so, generally describe. No. because project will be low. 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: Buildings have hpea sited to maximize solar access while minimizing grading. 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. Nn 1) Describe special emergency services that might be required. None anticipated. 2) Proposed measures to reduce or control environ- mental health hazards, if any: None b. Noise 1) What types of noise exist in the area which may affect your project (for example: traffic, equipment, operation, other) ?_adffjc.` 2) What types and levels of noise would be created by or associated with the project on a short - term or a long -term basis (for example: traf- fic, construction, operation, other)? Indicate what hours noise would come from the site. Some short -term noise during construction from equipment operation. some long -term .noise from traffic generated by the proposed action. 3) Proposed measures to reduce or control noise impacts, if any: None proposed. 8. Land and Shoreline Use a. What is the current use of the site and adjacent properties? Vacant and twn sing le_- family IMPC Uses North: vacant - finned PO South" F_ - 7nned RA Fast: Manufacturing - M -7 West: vacant .._in t P rpunty b. Has the site been used for agriculture? If so, describe. No. c. Describe any structures on the site. 2 rPsidenrpc_ Evaluation for Agency Use Only are: III d. Will any structures be demolished? If so, what? Yes. both residanres_ e. What is the current zoning classification of the site? RA f. What is the current comprehensive plan designation of the site? Low density residential with aecla L development considerations overlay g. If applicable, what is the current shoreline master program designation of the site? NA h. Has any part of the site been classified as an "environmentally sensitive" area? If so, specify. No. i. Approximately how many people would reside or work in the completed project? Reside: 240; work: 10 J. • Approximately how many people would the completed project displace? 2, 1Dyvners M � the_� 2 enants k. Proposed measures to ,avoid or reduce displacement impacts, if any: If they �diS , the dy�placeps m - reside in the proposed motion_ �J 1. Proposed measures to ensure the proposal is com- patible with existing and projected land uses and plans, if any: Discussion of maasure _ roposed to ensure compatibility with Single- family ch ter _ will he submitted separately _ -12- Evaluation for Agency Use Only 9. Housing a. Approximately how many units would be provided, if any? Indicate whether high, middle, or low - income housing? 144 middle- income units. • b. Approximately how many units, if any, would be eli- minated? Indicate whether high, middle, or low - income housing. 2 eliminated. One residence of owner and one renter. c. Proposed measures to reduce or control housing impacts, if any: None proposed. 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? 35 feet,. Either vinyl or wood sidinT b. What views in the immediate vicinity would be altered or obstructed? None c. Proposed measures to reduce or control aesthetic impacts; if any: 2 -story structures on portiQn_of the site visible from So. 178th. Three -story struc- tures not visible from off the si.e, Evaluation for Agency Use Only 11. Light and Glare Evaluation for Agency Use Only a. What type of light or glare will the proposal produce? What time of day would it mainly occur? There will hP sPrurity ligghting at night in the park- ing lute and huildingc entrances_ Some light will he generated h,y vehirlPc Pntering and exiting_the_ project at night_ b. Could light or glare from the finished project be a safety hazard or interfere with views? No. 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: Shielding and spotting of security lighting. 12. Recreation a. What designed and informal recreational oppor- tunities are in the immediate vicinity? Jogging paths; fishing in the Green River; shopping_ in the Southcenter area. 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: A recreation center will be constructed_Qn -site which will incltde_an indoor swimming _amt lad _a120.1 sluna and party lounge and an exercise room. Outdnoi recreation opportunities will include a barbecue (continued on attached sheet) -14- • 12. Recreation c. (continued) area; an outdoor play area for the daycare center, a climbing toys area; a tot lot and 2 sports courts which will either be for pickleball, volleyball or basketball. The extensive open space areas will be used for informal recreation and walking. • 13. Historic and Cultural Preservation a. Are there any places or objects listed on, or pro- posed for, national, state, or local preservation registers known to be on or next to the site? If so, generally describe. No. 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: NA Evaluation for Agency Use Only 14. Transportation a. Identify public streets and highways serving the site, and describe proposed accss to the existing street system. Show on site plans, if any. Streets serving the property are 57th Ave. S. So. 178th St.; So. 180th St. and Southcenter Parkway. Access to the project will be from _ _57th Av nup Smith_ b. Is the site currently served by public transit? If not, what is the approximate distance to the nearest transit stop? The site is served by Metro Route _12 , 187, and 155 with a stop at So. 180th and Southcenter Parkway. c. How many parking spaces would the completed project have? How many would the project eliminate? The project will have 307 parking,_spaces. Four spaces will be eliminated, d. Will the proposO require any new roads or stree , or improvements to existing roads or streets, not including driveways? If so, generally describe (indicate whether public or private). Impacts on roadways will be discussed in traffic study sub - mitted under separate cover. e. Will the project use (or occur in the immediate vicinity of) water, rail, or air transportation? If so,, generally describe. Nn_ f. How.many vehicular trips per day would be generated by the completed project? If known, indicate when peak volumes would occur. Traffic volumes from the school and the residential use will be discussed in the traffic study submitted under separate cover. . Proposed measures to reduce or control transpor- tation impacts, if any: Measures to reduce and control transportation impacts will be disc.vssed in traffic study submitted under separate cover. 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. The project would result in as yet undetermined increase in d n n for puhlir services: adl ice and b. Proposed measures to reduce or control direct impacts on public services, if any. Measures to re- duce and control direct impacts will be described under separate cover. -16- tva1uacnon tor Agency Use Only Evaluation for • Agency Use Only 16. Utilities a. Circle utilities currently available at the site: electric natural gas, water, re use servic , to ephone i sanitary sewer, septic system, other. 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. The site is in Water District 75; water service__ has not vet been evaluated. Sewer capacity in the area has been studied.py HortonlDennis & Assoc. _ Their findings will be addressed during subsequent analyses being undertaken for this project. 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: D Date Submitted: vic-e16 231 1 g7 PLEASE CONTINUE TO THE NEXT PAGE. tO BE COMPLETED BY APPL #VT O. SUPPLEMENTAL SHEET FOR NONPROJECT ACTIONS (do not use this sheet for project actions) • Evaluation for Agency Use Only Because these questions are very general, it may be helpful to read them in conjunction with the list of the elements of the environment. When answering these questions, be aware of the extent the proposal, or the types of activities likely to result from the proposal, would affect the item at a greater intensity or at a faster rate than if the proposal were not imple- mented. Respond briefly and in general terms. 1. How would the proposal be likely to increase discharge to water; emissions to air; production, storage, or release of toxic or hazardous substances; or production of noise? Proposed measures to avoid or reduce such increases are: 2. Now would the proposal be likely to affect plants, ani- mals, fish, or marine life? Proposed measures to protect or conserve plants, ani- mals, fish, or marine life are: Evaluation for Agency Use Only 3. How would the proposal be likely to deplete energy or natural resources? Proposed measures to protect or conserve energy and natural resourses are: 4. How would the proposal be likely to use or affect environmentally sensitive areas or areas designated (or eligible or under study) for governmental protection; such as parks, wilderness, wild and scenic rivers, threatened or endangered species habitat, historic or cultural sites, wetlands, floodplains, or prime farmlands?• Proposed measures to protect such resources or to avoid or reduce impacts are: 5. How would the proposal be likely to affect land and shoreline use, inclduing whether it would allow or encourage land or shoreline uses incompatible with existing plans? Evaluation for • • Agency Use Only Proposed measures to avoid or reduce shoreline and land use impacts area: How does the proposal conform to the Tukwila Shoreline Master Plan? 6. How would the proposal be likely to increase demands on transportation or public services and utilities? Proposed measures to reduce or respond to such demand(s) are: 7. Identify, if possible, whether the proposal may conflict with local, state, or federal laws or requirements for the protection of the environment. Evaluation for 0 Agency Use Only 8. Does the proposal conflict with policies of the Tukwila Comprehensive Land Use Policy Plan? If so, what poli- cies of the Plan? Proposed measures to avoid or reduce the conflict(s) are: TO BE COMPLETED BY APPLICANT Evaluation for • 0 Agency Use Only E. 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 aforegoing items of the Environmental Checklist. This information provides a general overall perspective of the proposed action in the context of the environmental infor- mation provided and the submitted plans, documents, suppor- tive information, studies, etc. 1. What are the objective(s) of the proposal? 2.. What are the alternative means of accomplishing these objectives? 3. Please compare the alternative means and indicate the preferred course of action: • • Evaluation for Agency Use Only 4. Does the proposal conflict with policies of the Tukwila Comprehensive land Use Policy Plan? If so, what poli- cies of the Plan? Proposed measures to avoid or reduce the conflict(s) are: -23- • 711-1 • ,,%7 John W. Denure. i� jr p Paul Jonientz 0 %.:� r IA • L ! \R +,:William M. Polk:': ?. ;' \ \ µ..• 1' r. Mario •A0 Segale 0 C Schneider Homes, Schneider Homes, Ray' Fl ink in.(l••.• Herman Schoenbachler f, `,Roy E. Martin co /PO Ole !7 Mario A. • 0 M' Mario A. Segale a r? 0 r Mario A. Segale �• N !I � V i h 04, 4P r }N 8 °L i 10 / Assessor's Map Source: King County Assessor URBAN REGIONAL RESEARCH Sylvan Glen Submitted by Primark Office Commercial Parks and Open Space Low Density Residential Heavy Industry Light Industry Comprehensive Plan URBAN REGIONAL RESEARCH Sylvan Glen Submitted by Primark P -O (Professional and Office) C -2 (Regional Retail) CM (Industrial Park) M -2 (Heavy Industry) R -A (Agricultural) CZ Zoning URBAN REGIONAL RESEARCH Sylvan Glen Submitted by Primark Vacant Land, Commercial Industrial Residential (Within 1000 foot radius) Existing Land Use URBAN REGIONAL RESEARCH Ju6n,:� "'I Wen Sylvan Glen Submitted by Primark 4. am: Pr ,A• • • e•-• • 4. .4.4,1••• **out. ow4413144 • • • •• 5f7UT STRZET ••••■• MOO V .D. 14-41•64..a. t•-•••••■••• eV ggp TDI VIC-U.11r( MAP s .? -2.. A •• A %Aro Dr 8 rm. ow 1r wor AV coos SITE PLAN.-ort giggp pap., agg pg ag • megpg • • On. i• •••• ADO, Woo 16 ...A. s• • AA.... G. Sao TV. Of ..4.1...OVIDN V.I Ka v..) AO. .447.4.6. va. 1 8 C ■ DuDpmf I 1 0 10 CI c 44 1 •11711•111■111U1ILMIINNIIRDI1E [113■NIMMININGEI9■OCE •11.. •=1B■11MMIIIDEDDIM HIIIIMEI tIJR! ,u, ..3G7=71 _arr7431•1111■ .: M... . ■ MD Wl a eo n j * u won M. rwa etommn wn h. 18 WOOD IWO MIO 6 SODOM I O • MI.( 10. ■••Vi I. 9 • .-7- V.IM-MIS RIMMIMNIII IDIMEMEED=RI. I■1I•1 FIE1 EEIILL-1DLLILIII 141MIMEMPIII=MI• I IIEMIUMNITAir■B • 23) SECTION A -A .A.��N.v ..0 w.� TTKWw4 WYWL 7.JI..17M4 • A2 • 1-arig ril ---11nuitallifit 1111 mieumml • END ELEVATION Stsaff5 RIN m Hamm IIIIiiI -51141i11111111111111111111I11— = TflII =1 11 HIfflIIIIIF =,— BUILDING — A SCALE 1/8" 1-0 REAR ELEVATION. FRONT ELEVATION AT HIGH GRADE EOM tr, N•M DIEm MIME limmum 3NRIF-Z- n Ma ammo• 0 11111aindlibbil t Ell FRONT ELEVATION AT LOW GRADE A3 1111111111011110J111111111 - - - - _ LEFT END ELEVATION in ----=-111115.1011 INN Immo — En -31 MB FRIO' !-5:411 111 L!JIiii BUILDING — B SCALE 1/8" = 1'-0" FRONT ELEVATION REAR ELEVAT ION EE Tirrig Li—P= 1111111111111r113111;711111 --wwit11111 RIGHT END ELEVATION s,? 4('‘' ■ A4 ,II�II, m =0 w i 7 t ��i0 VVIII:° II�IIIIN its - - -- END ELEVATION BUILDING — C A SCALE 1/9" FRONT ELEVATION 11-0- 1 - am mu inif11111 11111111111111k===== IptrA mit REAR ELEVATION A5 • www•IMINIIIr • I , i?J EAST ELEVATION RECREATION — DAYCARE BUILDING SCALE 1/8' = 1 • —0" • • . — — NORTH ELEVATION • WEST ELEVATION z , ! •tt .". _:-.--=-1 - -17- -.,,. 7.- -:i :- t': , i.,,,,;,:, .....:„.:__ ,., SOUTH ELEVATION CO E. A6 PLAIT MATERIAL LEGEND SYMB01. DDSCRIPflcN DESCRIPTION GEIMETIGLEEDISEEIS LYMEIR SIDURD Pbn ryMntri. /Sootrn Pie. P.ndd.o....nd..i /Douglas Fe Taiga b.t.rop »Yll. /me.en Hemlock Abin prear. /Nvbl. Fir Ch..rgp.ri. ls...ni.n./L...a Cypress textan.TR.Ac Am efcin.ten /Vb. M.M. Aar .ina.l. /Amur Mani* Aar r.br.. /Red Maple Qaroe. [arr../.bile Oak Qosras rubr./R.d Oak Can.. fl.ria./Flov.ring Dog.eod Peru aWrnp./Flov.riro Pear tr .la... ph..vopbfl.a Wttbiyta ee Th Lie tdambus .tyr.dfb./A merman Sonet.om agar.a bnk.eodi/Ormmen a...tbe. b.rkwadri/Del.ny amrnllu. Arbutus .ned. /Sir.vberre Tree Photinla fr...rii /Phmim. f IIoni. •Tr.d..ti•/Fr.d.. Exanania a.ith.ri .h.lb. /LW Plum .e.e ..go/Munbo Pine Ibei dndo. .pdAboaodendroe Viburnum dntdii /pnb viburnum My.in a.itfee.ica/P.dfw Wu Myrtle ' Y.aini.• orate. /Evergreen butkberry Munn. Mae. /Laurusan DIEJLEIDLUESIEN C.ne..lb./TM.n.a Dog.. Caren r.rla./Rolnig Dogwood LA.. M.Mis./St.b.n Sums Germ....pbl.n. /a.nb..ry Caton ..ee Pbtl.d.tpb...inbi.i. /Mai Onp Yib ..drop r dM P /A. Viburnum MjaS.. mybeny Viburnum pYat.m tomnuam /DaeblefiM Viburnum atemeaner dammed/Bear.. Catmesmer Ardat P i . m- n.1/1....y Thorn alma /Dvmf Prr1.M.M Bogor, both Thame.r•/Tha d.M Ivy • nmume 1' = 40' e.w . . DEVELOPMENT PLAN f Noil_VAQ-1 1Y012),_1_ -r 1 1 11111111111 1 City of Tukwila PLANNING DEPARTMENT 6200 Southcenter Boulevard Tukwila, Washington 98188 (206) 433 -1849 • PRE - APPLICATION PROJECT SUMMARY FOR STAFF USE ONLY Pre - application File # pre - app -(jl'; -n Date Received: 542-3g Meeting Date 5-26-g? Time a ;0O1O0)• Routing: VI BLDG 12 FIRE yi PLNG [2[ PWD g POLICE 2 PKS & REC 1. PROJECT INFORMATION Project Name Sylvan Glen Site Address 18059 Southcenter Parkway Description of Proposal Construction of a daycare center and 144 residential units Acreage of Site (gross)12.445 acres Anticipated Period of Construction: From Spring 1989 To Summer 1989 I Will project be developed in phases? ❑ Yes © No If yes, describe Identify existing easements on site: None 2. BUILDING INFORMATION Total Building Square Footage Type of Construction (1985 UBC) Please indicate the square footage of each floor, broken down by building use(s): BUILDING' USE AND OCCUPANCY CLAS'S'IFICATION SQUARE FOOTAGE 1st Floor / ./ 2nd Floor / 3rd Floor TOTAL TOTAL TOTAL (For additional floors please fill out another sheet) Storage or use of flammable, combustible or hazardous materials on premise or area of construction? ❑ Yes © No If yes, explain: Number of parking stalls proposed: Regular 335 Compact 8 Handicapped 11 3.. APPLICANT Contact Person Jane Preuss for Address 1809 7th Avenue; Suite 1000 Company Primark Prepared by: Jane Preuss Zip 98101 Phone# 624 -1669 Date 5/18/88 SYLVAN GLEN NOTES Pair 1 A i � � | / 1 C / 9 1 BUILDING INFORMATION .MUMB[R --- _., BUILDINGS . i . FT. GROSS .TOTAL FLOOR FLOOR AREA AREA 8Y 6LEG.TYPE 3,671 69 g363 3 BUILDING TYPE 4 A � 5 6 10 , 9,871 7.230. 11,700 ^ , , ^ ' . __ ,__ , --'--'—r----' �� 93/710 7.230 1 1/7UO 187/009 _ 4 _ ^________ , • . -- ,_---- , ~____ ' �� 6 C ^ 1 140_ ' ^ 7 BUILDING AND DAYCARE ~ _REC 8 9 TOTAL BUILDING SQ. FT. , 80 11 UNIT INFORMATION � 1 2 1 3 | 14 UNIT TYPE �JUANT|TY 3D ^ 5U 36^__ . 43 1 5 ONE BEDROOM TWO BEDROOM ONE BATH y6 87 TWO BEDROOM TWO BATH THREE BEDROOM 1 8 1 9 20 TOTAL UNITS 144 , - 7 1 22 ^ 23 PARKING INFORMATION 24 _— , 25 SPACES REQUIRED: 26 144 UNITS X 23PACES EACH 283 SPACES 2 7 DAYCARE: 7 EMPLOYEES X 28 1.5 SPACES PER EMPLOY[[ 11 SPACES 29�'5PAC[5 � ._;07 SPACES 29 --- -----''--- T0TA[8PAC[�R[QUfR[D 30 31 TOTAL SPACES PROVIDED Pair 1 • PRE - APPLICATION PLAN SUBMITTAL CHECKLIST • Pre - application plans should contain the following: Q 1. Vicinity map Q 2. Site plan (drawn to scale), including dimensioned property lines and iden- tifying the following: Q Building setbacks from property line 0 Width of any adjacent public right -of- way(s) Q Designated landscape areas J Easements (including railroad, Puget Power, etc.) (l Parking layout [x Truck loading area designations (none) a Access points and traffic circulation pattern EI Footprint of existing and /or proposed structures 0 Significant natural features (water, slopes, vegetation, etc.) Q Identify sites proximity to river environment if less than 1700' from river Q Topography map (for slopes over 15 %) Q 3'. Building layout, i'dentifyi"ng- the fol lowi ng :- 0 General layout Q Exits and exiting pattern ( Uses and dimensions of all spaces (Please check the appropriate boxes identifying what was included on your plans, and attach checklist to your pre - application submittal.) • City of �kwila PLANNING DEPARTMENT 6200 Southcenter Boulevard Tukwila, Washington 98188 (206) 433-1849 PI ME Pre -app File # PRE- APP - 017 -88 FOR STAFF USE ONLY Project Na Meeting Date 5 -26 -88 Time 2:30 pm Site Addre Checklist mailed to contact person (date): 5 -27 -88 STAFF PRESENT NAMES /TITLES E] Building (433 -1851) Duane Griffin, Bldg Offic ©Fire (575 -4404) Nick Olivas, Fire Marsha' © Planning (433 -1849) Vernon Umetsu, Assoc. P1z ['Public Works (433 -1850) Phil Fraser, Senior Engir ©Parki & Rec. (433 -1847) Don Williams, Director ® Police (433 -1806) Tom Kilberg, Crime Prever ❑Other ( - ) ❑Oth'er ( )- APPLICANT /REPRESENTATIVES PRESENT Contact Person: Name Jane Preuss Company /Title Prin Address 1809 7th Ave. Suite 1000, Seattle, WA Others Present: Name Guy Spenser Company /Title Prin Address 1809 7th Ave. Suite 1000, Seattle, WA Name Ray Flink Company /Title Prof Address Name Company /Titl.e. Address Name Company /Title Address Name Company /Title Address • • City of Tukwila PLANNING DEPARTMENT 6200 Southcenter Boulevard Tukwila, Washington 98188 (206) 433 -1849 PRE - APPLICATION CHECKLIST BUILDING DIVISION (construction) FOR STAFF USE ONLY Pre -app File # PRE- APP - 017 -88 Project Name: Sylvan Glen Meeting Date 5 -26 -88 Time 2:30 pm Site Address: 18059 Southcenter Py Occupancy Group R -1 CONSTRUCTION INFORMATION g 1. Comply with the provisions of the Uniform Building Cod Q, 1985 Edition (as �-- amended) . Coueid 5c fir( code dree.rid 1 an adop /o-n c vise o i ihe: eerie by Cit,>I., R 2. Comply with Washington State Barrier Free Code, 1987 Edition. 21 3. Comply with Uniform Mechnical Code, 1985 Edition. 0 4. Comply with State Energy Code. Provide energy calculations stamped by a Washington State Licensed architect or engineer. 5. Provide licensed Washington Architect stamp on construction drawings. f 6. Provide a soils report, stamped by a Washington State licensed engineer. 0 7. Submit structural calculations stamped by a Washington State licensed struc- tural engineer. 8. Obtaitn bu'i 1'dtngr permit. 9. Obtain mechanical permit. Roof top mounted equipment requires structural calculations stamped by a licensed engineer. 10. Obtain grading /fill permit. Q 11. Obtain separate permit for rack storage. Rack storage: must be designed for seismic zone 3. A licensed structural engineers stamp will be required for rack storage 8' and over. [[ 12. Obtain a sign permit (TMC Title 19). Ce; (� / 13. Special inspectors will be required-far � <r'T��eC� 6-e c, 304) O,13C. 14. Notify Building Official of testing lab hired by architect or owner (not by contractor). El 15. Obtain approvals and permits from outside agencies (see attached misc. and outside agencies checklist). o Electrical permit and inspections through Washington State Department of Labor and Industries, 872 -6012. o Plumbing permit and inspections through King County Health Department, 587 -2732. [I 16. King County Health Department must approve and stamp plans for restaurants and food service facilities prior to submittal to Tukwila Building Division. [ 17. Provide plan submittal Jp per requirements on attached plan submittal handout. 18. Tk1- )cC iTI07 /,S O _ �1 /o o o 0 1 fk e row La ke cd cicri2 [[ Checklist prepared by (staff): qdL2i0X f :see. // (9N'e ctka pia c r` ay, )4 E Date SI c 0 City of ikwila FIRE DEPARTMENT 444 Andover Park East Tukwila, Washington 98188 -7661 (206) 575-4.404 • PRE — APPLICATION CHECKLIST FIRE DEPARTMENT (construction) FOR STAFF USE ONLY Pre -app File # PRE - APP - 017 -88 Project Name: Sylvan Glen Meeting Date 5 -26 -88 Time 2:30 pm Site Address: 18059 Southcenter Py Occupancy Group R -L CONTRUCTION INFORMATION [� 1. The City of Tukwila has adopted the 1985 Uniform Fire Code. This and other nationally recognized standards will be used during construction and operation of this project. (TMC 16.16.120) [(5. Maximum grade is 15% for all projects. + 12f 6. Hose stations are required. (City Ord. #1141) Q 7. A fire alarm system is required for this project. (City Ord. #1327) Plans shall be submitted to the Tukwila Fire Marshal for approval, prior to commencing any alarm system work. Submit three (3) sets of complete drawings. This includes one 127 for our file, one for company file, and one for the job site. Special installations of fixed extinguisher systems, fire alarm systems, dust collectors, fuel storage, etc. require separate plans and permits. Plans to be submitted to the Fire Marshal prior to start of installation. (UFC 10.301) 9. Portable fire extinguishers will be required in finished buildings per N.F.P.A. #10. (Minimum rating 2A, 10 BC) . Fire hydrants will be required. (City Ord. #729) . Required fire hydrants shall be approved for location by the Fire Department, approved for purity by the Water Department, and fully in service prior to start of construction. A fire hydrant must be no further than 150 feet from a struc- ture; and no portion of a structure to be over 300 feet from fire hydrant. (UFC 10.301 and City Ord. #729) 4. Automatic fire sprinklers are required for this project. Sprinkler systems to comply with N.F.P.A. #13. Sprinkler plans shall be submitted to Washington State Surveying and Rating Bureau, Factory Mutual or Industrial Risk Insurers for appro- val prior to being submitted to Tukwila Fire Marshal for approval. Submit three (3) sets of sprinkler drawings. This includes one for our file, one for company file, and one for the job site. (City Ord. #1141) Q 10. Buildings utilizing storage of high piled combustible stock will require mechani- cal smoke removal per Section 81 of the 1985 UFC. 11. During construction, an all- weather access will be required to within 150 feet of the building. (UFC 10.301) 1262. No building will be occupied, by people or merchandise, prior to approval and inspection by Fire and Building Departments. Ef// 13. Adequate addressing is required. Number size will be determined by setback of building from roadway. Four inch numbers are minimum. Numbers will be in color which contrasts to background. (UFC 10.208) [714. Designated fire lanes may be required for fire and emergency access. This requirement may be established at the time of occupancy and /or after the facility is in operation. (UFC 10.207 as amended) 15. Special Fire Department permits are required for such things as: storage of compressed gas, cryogens, dry cleaning plans, repair garages, places of assembly, storage of hazardous materials, flammable or combustible liquids or solids, LPG, welding and cutting operations, spray painting, etc. (UFC 4.101) 16. Miscellaneous requirements L»ye4gE &/1004 404'440 die v tai /EfilmweAlk - rem, Yist -, -- / a 2N,e, nuha s ■ a.// aPD","/ /21 as nl t.e.-F Icefc 4,0a.•f/XC // u./re /Jte.vA' <_ Checklist prepared by (staff): Date .5 -2‘ /yam City of Tukwila FIRE DEPARTMENT 444 Andover Park East Tukwila, Washington 98188 -7661 (206) 575-4404 PRE - APPLICATION CHECKLIST FIRE DEPARTMENT (inspections) FOR STAFF USE ONLY Pre -app File # PRE- APP - 017 -88 Project Name: Sylvan Glen Meeting Date 5 -26 -88 Time 2:30 pm Site Address: 18059 Southcenter Py Occupancy Group R -1 INSPECTIONS REQUIRED BY FIRE DEPARTMENT Underground fire line from vault to riser a. Thurst block and rodding b. Type of pipe c. Depth of cover d. Flush e. Hydrostatic test f. Fire Dept. approved plans g. Materials and test certi- ficate Overhead sprinkler piping a. Hydrostatic test b. Trip test c. Alarm system monitoring test. d °... Fire Dept.' approved: pTans•.. e. Sprinkler head location and spacing Q 3. Underground tank a. Location b. Distance between tanks c. Distance to property line d. Depth of cover e. Vent piping, swing joints, fill piping, discharge piping f. Anchoring g. Hydrostatic test h. Separate Fire Dept. approved plans [(5. Fire alarm a. Acceptance test b. Fire Dept. approved plans [� 6. Hood and duct inspections a. Installation b. Trip test Checklist prepared by (staff): [[ 7. Spray Booth a. Location b. Fire protection c. Ventilation d. Permit [[ 8. Flammable liquid room a. Location b. Fire protection c•. Permit Q 9. Rack storage a. Permit b. Mechanical smoke removal c. Rack sprinklers d. Aisle width O 10. Fire doors and fire dampers a. Installation b. Drop testing 11. Fire final a. Fire Dept. access b. Bldg. egress and occupancy load c. Hydrants d. Bldg. address e. Fire protection systems (1) Halon systems (2) Standpipes (3) Hose Stations (4) Fire Doors (5) Fire Dampers (6) Fire Extinguishers 12. Other a. b. c. d. e. f. 9• CL) Date .T --R( SI PLANNING DEPARTMENT 6200 Southcenter Boulevard Tukwila, Washington 98188 (206) 433-1849 • PRE - APPLICATION CHECKLIST PLANNING DEPARTMENT (land use) FOR STAFF USE ONLY Pre -app File # Pre - App- 017 -88 Project Name: Sylvan Glen Meeting Date 5 -26 -88 Time 2:30 pm Site Address: 18059 Southcenter Pkwy. Zoning R -A LAND USE INFORMATION 2/1. Compliance with the Zoning Code (Title 18). 2. Obtain the following permits /approvals: (applications attached) _ Boundary Line Adjustment ��Building Site Improvement Plan Comprehensive Plan Amendment ✓Conditional Use PermitcPoR DAY CA,Q- ,/ Design Review Design Review - Interurban ✓Environmental (SEPA) Planned Mixed Use Development U 1. Proposed, use, compl4esp with, zoni ngr? Q 4. Structure meets setback requirements? Q 5. Proposal meetings minimum parking space standards? [[ 6. Roof -Top mechanical equipment screened? O 7. Site plan complies with andscape requirements. ✓Planned Residential ✓ - Rezone As _ S• horeline Management _ Shoreline Management - Short Subdivision — S• ubdivision - Unclassified Use — Variance, for Development* Pao fos eD Permit Permit Rev. Yes,✓o:. Yes No MA ■ Yes No Yes No N/A Ls No U 8. Cov"Ci L- QR-ev 0 c)S 0 C) Y (A( 1C•47C1) U 9. if A'S A SUFF(G(oneT Amo'J'rT of M rf-FA-M,c,Y ^'e'b t-*i'4 [[ 10. 5.:4r4E7 M riA(G 7,faT�s Q 11. A s s c : Hipc. � � /o Goat PACT s rA c c..t' U 12. PRov/2),6- £(C 404 r(onr , 7F, l 8. 5a,. O 60 Q 13. Q 14. O 15. Q 16. O 17. U 18. U 19. U 20. Checklist prepared by (staff): Date Z 278e City of 1Ukwiia 6200 Southeenter Boulevard Tukwila. Washington 98188 Public Works Department 433 -1850 PRE - APPLICATION CHECKLIST PUBLIC WORKS (utilities) FOR STAFF USE ONLY Pre -app File # PRE- APP - 017 -88 Project Name: Sylvan Glen Meeting Date 5 -26 -88 Time 2:30 pm Site Address: 18059 Southcenter Py CONSTRUCTION INFORMATION 12[C 1. 8bte-i-nThe following permits 7 X viflL�o Channelization /Striping /Signing Curb Cut /Access /Sidewalk Excavation (public) Fire Loop /Hydrant (main to vault) Flood Zone Control '1 Hauling (2,000 Bond, Cert. Ins.) lirLandscape Irrigation Moving an Oversized Load Sanitary Side Sewer - Other -4 Sewer Main Extension (private) X( Sewer Main Extension (public) Storm Drainage Water Main Extension (private)' '`- i)/ Water Main Extension (public) Water Meter (exempt) Water Meter (permanent) Water Meter (temporary) 7s [ 2. Water and sewer assements may apply. and will be determined during the utility plan review process. Q 3. Provide sidewalks per Ordinance #1158, #1217 and #1233, or obtain waiver. Q 4. Provi'de traffic analysis for: Q 5. Provide developers agreement for: Q 6. Provide Hydrological-Geotechnical analysis. S c r itiun -rru Agn•..� -� Co (-7 t,3 sb g s% n K-1N4 AT N k� jZA►MPs AT ►- \ El 7. Review traffic study prepared by ( (ltfARae. 1E.1\161 - s 1s3$±" Colve.icc?- & ?ED- l c. AP Me INFbn -m410 3 ul`�C -rt' Q 8. Provide plan submittal per requirements on attached plan submittal handout. Q 9 Q 10. Q 1 . SEW AV A-1 1 L1 T `1 S F-1421- LL E. F TERIY1►►v0") Q 12 . rt (\-D U EA R c o) — &-o f 1v(r f l) (LION DEN N Is .S^TU 1)-) Q 3: 01 Sr)LM1 -BD Sc w s`(S; �- Q 14. Ce, (A4111 (IV I D FUTUite. L(PS1WluL OF MI�11.5 Q 15. ( - 7Y1 4- /INS ID Q s--0\-M c) , Pl) -U) I'Yl -ET IF "Po sS L f ) t_LT 1 �S . Q 17. 18. LI Yv1 ova 1=lZ Q 19. C N 7-0 r1TJ w A'`'1� i 5 �= AVE 5, w (L-c_ (3� Q 20. • A1D"'l1 —ry T(v -�/�2 f�Li*. s1Tt> SL(3111 Checklist prepared by (staff): Date 5/D (otgS • tit 11 0 S. 178TH STREET • %t • SCALE: 1'= 100' CENTRAC ASSOCIATES CONNECTIONS TO 178th/ 180th ST. ALTERNATIVE E 1 -5 at S. 188th to S. 180th 30 FIGURE 12 27 1-14-1( WIL A CI 9037 King, ounty ALTERNATIVE E�_1 ORIGINAL "E" SPUR LINE 9033 01s Schneider Homes Inc.' 9109 /Schneider Homes Inc. ALTERNATIVE D Herman Schoenbachler' 9039 9090 John W. Deniire 9019 ?. Paul (l' Jonientt ALTERNATIVE C, • 9015 Herman Schoenbachler 9040 Roy E. Martin 9050 57th Ave. M. A. Segale 90316 9032 9055 M. A. Segale M. A. Segale 9055 M. A. Segale REVISION 12/10/84 APPROXIMATE SCALE (Per new topo mapping) ALTERNATIVE ALIGNMENTS AND PROPERTY OWNERSHIP 18 FIGURE 4 tit • co S• 178T N STREET • • SCALE: 1.= 100' CENTRAC ASSOCIATES CONNECTIONS TO 178th/ 180th ST. ALTERNATIVE E 1 -5 at S. 188th to S. 180th 30 FIGURE 12 • CI IMIT3 ALTERNATIVE Et 9037 King. °linty 9012 Schneider Homes Inc. 9033 Schneider Homes Inc. 109 •Schneider Homes Inc. ALTERNATIVE D 9040 Roy E. Martin 9015 Herman Schoenbachler 1 57th Ave. M. A. Segale 903$ 9032 9055 M. A. Segale M. A. Segale REVISION 1200/84 APPROXIMATE SCALE (Per new topo mapping) 1'= 200' 9055 M. A. Segale 9031 Robert Schoenbachler ALTERNATIVE ALIGNMENTS AND PROPERTY OWNERSHIP FIGURE 4 18 ,/r-rrio -wooro (2ko2 0A-1/0) cr? d - 72,?-7-773 o2 _?--ovnrvo c/r7r/i9ioi I frplirotl, • 070pr7 ,71 /7/27ni -2-)9 ,r7q6e-k-d-7r0 -eryivv- 1i - -)/x0 //7 01 /7'1 2 o,r)g • 29-7.,7?-7 cy--i-vkK) /-2/ /7 72-2 cfrP c/l2POi /7P 14P j-Y77 ?DID 14-9--124/ v770 '- WX-103-(00 "70 ruir7,027( 02--)7197 01/14(77 c r-r7e1-26,1 ).0 We?-2-S-% e 20 p_c)-rorio-po -7--e?yrin "rpQ g 26/ w-e--o-27 - 1t-oe- r trruozo mfoio (?)-74f2s rY70,1//,/0/-- P-R9/pi2 (0-7-0.1,76; or-r-n41 • .. • •• Vrr—vrpa (-7.—v/7r70 T1cf L - rig a ; ✓o/c' ariv/-7971 fl7? 7 - 2- w) m 02 i'QO & -x-/-2v7-79 7-YrY-P-7-720 - -tprp r .. 1 1'0 p0,90/0/ S S / Old/ � z "ti V2 • rd r11,77 ?,m o_72 8 8b/ - vv/ '71-) ✓U /5.q, -cV77 _ / g - r?'-if914-7040 o� O ,/o zo 79?-0-0 '(Y? - 1/1 /M1.9 70, i&-oi 194-77 - Avg 77 - ?.r torY voutv a.‘ ?-0/-6 (prn-o- r )01 lemon lei - L (,�TV , Li () c/a dil 507"64, .�J gtf. Ci 4-e (i274-1,t ie,tl a ?,oc w ni CLeDq,. C/74 , '46a-4-td 1240 ow, 60h ' 5- 02' bin./ 'ed u.� E 5 av o-kio9 c.�.: >-e-d( , te_.,40 0 2o2./L-JG( _ aL c.,ts o, 4107,0-ev -e911 iPj()e, - lea Z-ecGcot)cGLI cpicy zio t1- 9 1-tx1 - ,11°/7L(31 (921 - ,--171'ra,--t7ic , z-0/LE W 1,1, a& (.one, )04_0cc5-3. Aokyy,t2 90/.o/0cLtaL& On4, cU2eQ,eezQ �ti-1)-1 cGi �a-e �v d1o4v22), c��, ✓ CGS Co' �!'�C 9L- CeMikttuu)4-k inCtitu70 g_te>r,a -ion 9 Feco,dily C1✓-(4, (�,l.b- 1C l3� e � tA,o• (,uct.,d) , 47;0")1 ea.o-ed -000y-da, _ r'actia �c�o bzf• 41,/d_dea -v Q.Lv 01, PO tVa L C a '