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rl Afr �G ON A Pp 6 #.i r i l / f• - .. f f% GEOTECHN1CAL ENGINEERING SERVICES .- PRESIDENT PARK SUBSTATION RENTON, WASHINGTON FEBRUARY 22, 2006 FOR PUGET SOUND ENERGY GEOENGINEER Frle No. 0186-673-00 Geotechnical Engineering Services President Park Substation Renton, Washington File No. 0186-673-00 February 22, 2006 Prepared for: Puget Sound Energy P4 Box 90868, EST-04W Bellevue, Washington 98009-0868 Attention: Fred f_unki, PE Prepared by: GeoEngineers, Inc. Plaza 600 Building 600 Stewart Street, Suite 1700 Seattle, Washington 98101 (206)-728-2674 GeoEngineers, In Snd I othy D. Bailey otechnical Eno McFadden, PE, LEG TB2:JJM.jm:ta RE DM :1010186 8 7 MOTi n a1 s1018 6673 00R _ doc Copyright® 2006 by GeoEngineers, Inc. All rights reserved. Disclaimer Any electronic form, facsimile or hard copy of the original document (email, teatt, table, and/or figure), if provided, and any attachments are only a copy of the original document. 1-be original document is stored by GeoEngineers, Inc. and will serve as the official document of record. File No_ 0186-673-00 TABLE OF CONTENTS Page No. INTRODUCTION........................................ ................ ............................ .. ...................... ......... 1 PROJECTDESCRIPTION .......... ............................................... .................. ....................... - ........................ 1 FIELD EXPLORATION AND LABORATORY TESTING..............................................................................1 FIELDEXPLORATIONS ................... ............. ..—................................... ............................................. 1 LABORATORYTESTING.. .................................................................... ....................... .................... 2 SITECONDITIONS.........................•---..................------...........................---.................................................... 2 SURFACECONDITIONS ............... ..................... ..................... .................................................. •....... 2 GEOLOGY......•...................•-......................---..................................... .................. SUBSURFACE CONDITIONS............................................................................................................2 GROUNDWATER CONDITIONS........................................................................................................3 INFILTRATION TESTING ............................................ ................................................. ....... ... ......... 3 CONCLUSIONS AND RECOMMENDATIONS ........... .................. ... ....................... ...................................... 4 SUMMARY........................... ............. ................................................... ............................................... 4 EARTHQUAKE ENGINEERING.........................................................................................................4 EARTHWORK............. ......... .......................... ..................................................................................... Excavation Considerations.... ............................................ 5 .................... .................................. 5 Clearingand Grubbing ............................................................................................................. 5 SubgradePreparation.................................................................................... .......................... 5 Erosion and Sedimentation Control........................................................................................... 5 StructuralFill ..................................... ..................................................................................... ...6 Weather Considerations...................................•--..................................,.................I................. 7 TemporarySlopes..................................................................................................................... 7 PermanentSlopes ................................................ ....................................... .............................. 8 SHALLOW FOUNDATIONS/ MAT FOUNDATIONS.......................................................................... 8 Allowable Bearing Pressure...................................................................................................... 8 Embedment............................................................................. ... 8 Settlement...................................................................................................................•.............. 8 LateralResistance.....................................................................................................................9 Construction Considerations.... . ................................................................. .............................. 9 RETAININGWALLS........................................................................................................................... 9 General...................................................................................................................................... 9 WallDrainage.. ........................ ........ ..... — ..................... .......................................................... 9 SITE DRAINAGE AND INFILTRATION... ............................ --.— ...................................................... 10 PAVEMENT RECOMMENDATIONS ... .................................... ..... .... ............. ................... I............... 10 Subgrade Preparation...................................................................................... Asphalt Concrete Pavements ... ......................................................... -.................................... 10 LIMITATIONS.............................................................................................................................................. 11 REFERENCES........................................................................................................................... . 11 File Na 0186-673-00 Page i GWENGINEER February 22, 2006 TABLE OF CONTENTS (CONTINUED) Page No. List of Tables Table 1. Infiltration Rate Test Results.......................................................................................................... 3 Table 2. 2003 IBC Seismic Parameters....................................................................................................... 4 List of Figures Figure 1. Vicinity Map Figure 2. Site Plan APPENDICES APPENDIX A —FIELD EXPLORATiONS..................................................................................................A-1 Appendix A Table and Figures Table A-1. Soil Description and Field Screening Results Figure A-1. Key to Exploration Logs Figures A-2 and A-3. Log of Test Pits Figures A-4 through A-9. Log of Hand Augers APPENDIX B — LABORATORY TESTING ................................................ ................................................ B-1 Appendix B Figures Figure B-1. Sieve Analysis Results APPENDIX C— REPORT LIMITATIONS AND GUIDELINES FOR USE ......................................... C-1...C-3 File No. 0186-673-00 Paged GMENGINEERtr.V February 22, 2006 GEOTECHNICAL ENGINEERING SERVICES PRESIDENT PARK SUBSTATION RENTON, WASHINGTON FOR PUGET SOUND ENERGY INTRODUCTION This report summarizes the results of our geotechnical engineering services for the proposed improvements to the existing President Park substation. The substation is located at 475 Union Avenue NE, as shown on the Vicinity Map, Figure 1. The layout of the proposed improvements is shown on the Site Plan, Figure 2. Our geotechnical engineering services were completed in general accordance with our proposal dated. January 5, 2006. Our scope of work includes: • Completing test pits and hand explorations at the site; • Completing infiltration tests at the site; • Completing laboratory testing on selected soil samples from the borings; • Providing geotechnical conclusions and recommendations for the proposed improvements; and • Preparing this report. GeoEngineers also completed environmental services which are summarized in a separate report, "Soil Characterization Services, President Park Substation, 475 Union Avenue NE, Renton, Washington". PROJECT DESCRIPTION Our understanding of the project is based on our meeting with you and review of a preliminary site plan dated December 14, 2005 provided by PSE. We visited the site on January 2, 2006 to evaluate access considerations and develop an appropriate exploration plan. We understand that the existing substation will be demolished as part of this project. We also understand that the new substation will consist of two dead-end towers, a 115 kV transformer, and lightly loaded electrical equipment. The dead end towers will support three conductors, each with a 3 kip tension load at a height of 35 feet. The transformer will weigh up to 150 kips and be supported on a 12 foot by 14 foot by 1 foot thick mat. Other equipment includes a future structure for gas breaker and switches. This equipment will weigh about 17.5 kips and be supported on a 14 foot by 16 foot by 2.25 foot thick slab. The substation will have room for future expansion to include another transformer. The proposed substation will be expanded to the west of the existing substation footprint. An additional driveway will be constructed from the substation east to Union Avenue NE. Some grading will be required to establish site grades, including removal of up to 4 feet of soil across the existing substation pad. Retaining walls will be required to support the fill at the northwest corner of the new substation fence as well as the north edge of the new access driveway. An infiltration facility will be used to manage stormwater from the substation. FIELD EXPLORATION AND LABORATORY TESTING FIELD EXPLORATIONS The subsurface conditions at the site were evaluated by completing two test pits, TP-1 and TP-2, to depths of 8V feet below existing site grades. We also completed six hand explorations, HA-1 to HA-6, to depths File No. 0186-673-00 Page I GEOENG IN EE RS February 2Z 2006 of 4 to % feet below existing site grades. The locations of the test pits and hand explorations are shown on the Site Plan, Figure 2. A detailed description of the field exploration program is presented in Appendix A. We also performed IS hand explorations, B-1 to B-18, inside the substation as part of our soil characterization services for the environmental portion of this project. A summary table (Table A-1) of these explorations is included in Appendix A. LABORATORY TESTING Soil samples were collected during the exploration program and taken to GeoEngineers' laboratory for further evaluation. Selected samples were tested for the determination of moisture content, fines content (material passing the U.S. No. 200 sieve), and grain size distribution (sieve analysis). A description of the laboratory testing and the test results are presented in Appendix B or on the exploration logs, as appropriate. SITE CONDITIONS SURFACE CONDITIONS The site is located in a residential area with multifamily residential properties on the north, south, and west, and Union Avenue NE on the east. The site is currently occupied with an active substation, which includes a dead-end tower, a transformer, and other electrical equipment. The substation is surfaced with gravel and surrounded by a chain -link fence, and a cell tower is located east of the fence. The site is accessed from a paved asphalt concrete driveway off of Union Avenue NE_ There is a 5 feet rockery at the southeast corner of the site on the neighboring property. Utilities at the site include underground power, communications and overhead power. The substation is approximately 10 to 13 feet higher than the surrounding area. The ground surface slopes up from the east, north, and west at about 2H:1 V (horizontal to vertical) and the existing substation} are located at the top of the slope in a fairly level area at about Elevation 413 feet. The residential properties to the south are built into the slope, so there is little grade change on the south side of the substation. Vegetation on the site includes grass, shrubs, and landscaping on the east side of the site and immediately adjacent to the substation fence. There are maple trees and blackberries on the west side of the site, and maple trees and brush in the northeast corner of the site. There is no landscaping inside the perimeter of the substation. There are no surface water features in the vicinity of the site. GEOLOGY Geologic information for the project area (Mullineaux, 1965) indicates that native surficial soils at the site are composed of glacial till. Glacial till commonly consists of a very compact, poorly sorted, non -stratified mixture of clay, silt, sand, gravel and cobbles. Till may include cobbles and large boulders. SUBSURFACE CONDITIONS Based on the explorations performed at the site, the subsurface conditions generally consist of fill and recessional outwash overlying dense glacial till. On the west side of the site, we observed 2'/2 to 3 feet of fill consisting of loose to medium dense silty sand with gravel. The fill was underlain by recessional outwash underlain by loose to medium dense silty File No. 0186-673-00 Page 2 GMENGINEER February 22, 2006 sand with varying gravel content which generally extended to the depths explored, except in TP-2. In TP-2, glacial till consisting of dense silty sand with gravel was encountered below the recessional outwash at a depth of 7'h feet, and extended to the depth explored. In the area of the substation and to the east of the substation, we encountered loose to medium dense silty sand with varying gravel content which extended to the depths explored (3 to 5% feet below the ground surface). We interpret this silty sand to be regraded and native recessional outwash. We observed approximately 3 to 12 inches of gravel surfacing in and around the existing substation. GROUNDWATER CONDITIONS At the time of our exploration on January 12, 2005, the region had experienced 25 consecutive days with measurable precipitation. We observed groundwater at a depth of 6 feet below the ground surface (Elevation 401 feet) in TP-1. We observed that the soil became moist to wet at depths of about 4 feet in the explorations inside the substation, and we encountered groundwater at depths of 3% and 4 feet (Elevation 408.5 and 408 feet) in HA-1 and HA-2, respectively. During our subsequent explorations on February 1, 2006, which was during a drier period, we did not encounter groundwater in explorations IIA4 to IIA-6, completed for the purpose of infiltration tests, although HA-6 was in an area where we observed groundwater on January 12. Based on our observations of groundwater conditions, we interpret that the groundwater and moisture encountered near Elevation 408 to 409 feet represents stormwater perched on top of the dense glacial till encountered in TP-2. It appears that the groundwater at the site infiltrates and generally flows downhill to the northwest corner of the site. The ground at the northwest corner of the site was observed to be soft and wet. INFILTRATION TESTING The City of Renton requires that infiltration facilities be designed in accordance with King County regulations. King County requires infiltration testing, so we performed falling head infiltration tests at three of the exploration locations, HA-4 to HA-6 on February 1, 2006. The tests were performed in general accordance with the procedure described in Reference 6-A of the King County Surface Water Design Manual. To perform the falling head infiltration tests, 6-inch-inside-diameter PVC pipes were seated at least 6 inches into native soils at depths corresponding to the approximate elevation of the proposed infiltration facility. The infiltration rate tests were conducted by filling each pipe with approximately 6 inches of water above the native soil. The infiltration rates were measured for total water level drops of 6 inches. The tests were repeated five times at each location and the results at each location were averaged. The results of the infiltration rate tests are presented on Table 1, together with the depths of each test. Table 1. Infiltration Rate Test Results Location Elevation of Test (feet) Infiltration Rate (inches/hour) HA-4 409 8.1 7.7 HA-5 407� 407 HA-6 5.1 File No. 0186-673-00 Page 3 G WENG IN EER � Fe6ruQry 11, 2006 CONCLUSIONS AND RECOMMENDATIONS SUMMARY A summary of the primary geotechnical considerations is provided below. The summary is presented for introductory purposes only and should be used in conjunction with the complete recommendations presented in this report. • The site is designated as seismic Soil Profile Type D per the 2003 International Building Code (IBC). • On -site soils are suitable for re -use as structural fill during periods of dry weather and may be suitable during wet weather as well, provided they can be moisture conditioned to meet compaction requirements. If on -site soils cannot be adequately compacted during wet weather, imported gravel borrow should be used. • Substation equipment, including dead-end towers, can be supported on shallow foundations with an allowable bearing pressure of 3,500 psf, a passive resistance of 250 psf, and a base friction value of 0.4. We estimate total settlement on the order of % to I inch. • The northwest corner and the new access drive extending to the northeast areas of the substation expansion can be supported using 2- or 3-block-high Ultra Block walls (5 to 7'/2 feet high). Reinforcing geotextile will be required for walls taller than 5 feet, on supporting sloping backfill. • New pavements for the driveways may consist of the standard PSE pavement section, with 3 inches of asphalt concrete over 10% inches of top and base course. Our specific geotechnical recommendations are presented in the following sections of this report. EARTHQUAKE ENGINEERING GeoEngineers evaluated the site for seismic hazards including liquefaction, lateral spreading, fault rupture and earthquake -induced slope instability. Our evaluation indicates that the site does not have liquefiable soils present and therefore also has no risk of liquefaction -induced lateral spreading. In addition, the site has a low risk of fault rupture or scismically-induced slope movement. We recommend the 2003 International Building Code (IBC) parameters for Site Class, short period spectral response acceleration (Ss), 1-second period- spectral response acceleration (Si), and Seismic Coefficients FA and Fv presented in Table 2. Table 2. 2003 IBC Seismic Parameters Recommended . 2003 IBC Parameter Value' Site Class D Short Period Spectral Response Acceleration, SS (percent g) 138 1-Second Period Spectral Response Acceleration, S, (percent g) 47 Seismic Coefficient, FA 1.0 Seismic Coefficient, Fv 1.53 File No. 0186-673-00 Page 4 GEOENGINEERS r.41 February 22, 2006 EARTHWORK Excavation Considerations Pill, recessional outwash, and glacial till were observed in the explorations. We anticipate that these soils can be excavated with conventional excavation equipment, such as trackhoes or dozers. Cobbles were encountered in the soils at the site. While boulders were not observed in the explorations, they may also be encountered, and the contractor should be prepared to remove them where necessary. Clearing and Grubbing Removal and demolition of existing substation structures should include removal of foundation elements. Existing voids or new depressions created during site preparation should be cleaned of loose soil or debris and backfilled with structural fill. Trees, brush and other vegetation, including topsoil with roots, should be stripped and removed from areas where structural fill will be placed. The stripped material should be placed in landscaping areas or taken off -site for disposal. Subgrade Preparation In areas where structural fill is to be placed, the upper 12 inches of existing subgrade soils should be compacted and evaluated prior to fill placement through either probing or proof -rolling with heavy, rubber -tired construction equipment. Likewise, the exposed subgrade in the proposed foundation areas for structures and retaining walls should be evaluated after site grading is complete. Probing should be used to evaluate the subgrades where proof -rolling is not possible or if site grading takes place during wet weather. Soft zones noted during proof -rolling or probing should be excavated and replaced with compacted structural fill. Fill placed on existing slopes which are steeper than SH:1V should be properly keyed into the native soil slope surface. This can be done by constructing the fill in a series of 6- to 8-foot wide horizontal benches cut into the slope. Bench surfaces should be constructed in accordance with Section 2-03.3(14) of the 2006 WSDOT Standard Specifications, and should be thoroughly compacted prior to placing the fill soils. Erosion and Sedimentation Control Potential sources or causes of erosion and sedimentation depend upon construction methods, slope Iength and gradient, amount of soil exposed and/or disturbed, soil type, construction sequencing and weather. The project impact on erosion -prone areas can be reduced by implementing an erosion and sedimentation control plan_ The plan should be designed in accordance with applicable city and/or county standards. The plan should incorporate basic planning principles including: • Scheduling grading and construction to reduce soil exposure; • Retaining existing vegetation whenever feasible; • Revegetating or mulching denuded areas; • Directing runoff away from denuded areas; • Minimizing the length and steepness of slopes with exposed soils; • Decreasing runoff velocities; • Confining sediment to the project site; and • Inspecting and maintaining control measures frequently. File No. 01 &6-673-00 Page 5 GEOENG IN EER February2Z 2006 We recommend that graded and disturbed slopes be tracked in place with the equipment running perpendicular to the slope contours so that the track marks provide a texture to help resist erosion and channeling. Some sloughing and raveling of slopes with exposed or disturbed soil should be expected. Temporary erosion protection should be used and maintained in areas with exposed or disturbed soils to help reduce the potential for erosion and reduce transport of sediment to adjacent areas. Temporary erosion protection should include the construction of a silt fence around the perimeter of the work area prior to the commencement of grading activities. Permanent erosion protection should be provided by re-establishing vegetation using hydroseeding and/or landscape planting. Until the permanent erosion protection is established and the site is stabilized, site monitoring should be performed by qualified personnel to evaluate the effectiveness of the erosion control measures and repair and/or modify them as appropriate. Provisions for modifications to the erosion control system based on monitoring observations should be included in the erosion and sedimentation control plan. Structural Fill Materials. Materials used to raise site grades, placed to support structures or pavements, or used for utility trench backfill is classified as structural fill for the purpose of this report. Structural fill material quality varies depending upon its use as described below: 1. On -site soils may be used as structural fill during dry weather. On -site soils may also be used during wet weather provided that they can be moisture conditioned to meet compaction specifications. If on -site soils cannot be moisture conditioned, imported gravel borrow (WSDOT Standard Specifications Section 9-03.14(1)) should be used. 2. Structural fill placed as crushed surfacing top course below pavements should conform to Section 9-03.9(3) of the 2006 WSDOT Standard Specifications. Pavement base course aggregate should conform to Puget Sound Energy Specification 1275.3110. 3. Structural fill placed as yard surfacing material should conform to Puget Sound Energy Specification 1275.1330 as described in the following table: US Standard Sieve size Percent Passing (by weight) " VA inches 100 1 inch 90 to 100 '1+ inch 0 to 15 318 inch 0 to 5 Fill Placement and Compaction Criteria. Structural fill should be mechanically compacted to a firm, non -yielding condition. In general, structural fill should be placed in loose lifts not exceeding 8 to 10 inches in thickness. Each lift should be conditioned to the proper moisture content and compacted to the specified density before placing subsequent lifts_ Structural fill should be compacted to the following criteria: 1. Structural fill placed below foundations, pavement areas or to establish yard grades should be compacted to at least 95 percent of the maximum dry density (MDD) estimated in accordance with American Society for Testing and Materials (ASTM) D I557. Structural fill placed to form finished slopes should also be compacted to at least 95 percent of the MDD. 2. Structural fill placed behind retaining walls should be compacted to between 90 to 92 percent of the MDD estimated in accordance with ASTM D 1557. Hand operated compactors should be used within 5 feet behind the wall. File No, 0I86-673-00 Page 6 GEoENGINEERSr/P February22, 2006 3. Structural fill (including utility trench backfill) placed outside of areas where foundations, roadways, parking and yard areas are to be located should be compacted to at least 90 percent of the MDD estimated in accordance with ASTM D 1557. 4. Crushed rock base course placed as structural fill below pavements should be compacted to at least 95 percent of the MDD estimated in accordance with ASTM D 1557. We recommend that a representative from our firm be present during proof -rolling and/or probing of the exposed subgrade soils in structure and pavement areas prior to the placement of structural fill and also during the placement of structural fill. Our representative would evaluate the adequacy of the subgrade soils and identify areas needing further work, perform in -place moisture -density tests in the fill to evaluate if the work is being done in accordance with the compaction specifications, and advise on any modifications to procedures that may be appropriate for the prevailing conditions. Weather Considerations The native soils contain a sufficient percentage of fines (silt) and are moisture sensitive. When the moisture content of these soils is appreciably above the optimum moisture content, these soils become muddy and unstable, operation of equipment on these soils will be difficult, and it will be difficult to meet the required compaction criteria. Additionally, disturbance of these near surface soils should be expected if earthwork is completed during periods of wet weather. The wet weather season generally begins in October and continues through May in the Puget Sound region; however, periods of wet weather may occur during any month of the year. The optimum earthwork period for these types of soils is typically June through September. If wet weather earthwork is unavoidable, we recommend that: + Stockpiles of on -site soils that will be used as structural fill during wet weather be covered with plastic sheeting to protect them from rain. If on -site soils cannot be moisture conditioned to meet compactions requirements during wet weather, imported gravel borrow should be used as discussed previously. The ground surface in and around the work area be sloped so that surface water is directed away from the work area. The ground surface should be graded such that areas of ponded water do not develop. Measures should be taken by the contractor to prevent surface water from collecting in excavations and trenches. Measures should be implemented to remove surface water from the work area. Temporary Slopes The soils encountered at the site are classified as Type C soil in accordance with the provisions of Title 296-155 WAC (Washington Administrative Code), Part N, "Excavation, Trenching, and Shoring." We recommend that temporary slopes in excess of 4 feet in height be inclined no steeper than 1'/2H:1 V. Flatter slopes may be necessary if localized sloughing occurs. For open cuts at the site we recommend that: • No traffic, construction equipment, stockpiles or building supplies be allowed at the top of cut slopes within a distance of at least 5 feet from the top of the cut. • Exposed soil along the slope be protected from surface erosion using waterproof tarps or plastic sheeting. • Construction activities be scheduled so that the length of time the temporary cut is left open is kept as short as possible. File No. 0186-673-00 Page 7 GMENGINEERL�g February 12, 1006 • Erosion control measures be implemented as appropriate such that runoff from the site is reduced to the extent practical_ • Surface water is diverted away from the excavation. The general condition of the slopes be observed periodically by a geotechnical engineer to confirm adequate stability. Since the contractor has control of the construction operations, the contractor should be made responsible for the stability of cut slopes, as well as the safety of the excavations. All shoring and temporary slopes must conform to applicable local, state and federal safety regulations. Permanent Slopes We recommend that permanent cut and fill slopes be constructed no steeper than 2H:1V. To achieve uniform compaction, we recommend that fill slopes be overbuilt slightly and subsequently cut back to expose properly compacted fill. To reduce erosion, newly constructed slopes should be planted or hydroseeded shortly after completion of grading. Until the vegetation is established, some sloughing and raveling of the slopes should be expected. This may require localized repairs and reseeding. Temporary covering, such as clear heavy plastic sheeting, jute fabric, loose straw or excelsior matting should be used to protect the slopes during periods of rainfall. SHALILOw FOUNDATIONS/ MAT FOUNDATIONS Allowable Bearing Pressure We recommend the substation equipment be supported on conventional spread footings or mat foundations bearing on either the native soils or on properly compacted structural fill placed over the native soils. The mat foundations and spread footings, where required, may be designed using an allowable soil bearing value of 3,500 pounds per square foot (psf). An allowable edge pressure of 4,000 psf may be used in the design of dead end tower foundations. The allowable soil bearing values apply to the total of dead and long -tern live loads and may be increased by up to one-third for transient loads such as wind or seismic forces. A subgrade modulus of 200 pounds per cubic inch (Pei) may be used for the design of mat foundations. Embedment In general, we recommend that the bottom of foundations be founded at least 18 inches below the lowest adjacent grade for frost protection. The foundation embedment depth may be reduced to 12 inches for small, lightly loaded footings where frost action will not affect equipment performance or an additional 6-inch thickness of non -frost susceptible gravel may be placed below the foundations to achieve an embedment of 18 inches. The gravel should meet the requirements of `yard surfacing material" presented above_ Settlement Provided all loose soil is removed and the subgrade is prepared as recommended in the "Construction Considerations" section below, we estimate that the total settlement of shallow foundations will be on the order of % to 1 inch. Differential settlements are expected to be less than % inch. File No. 0186-673-00 Page 8 GEOENGINEERir.2 February 22, 2006 Lateral Resistance Lateral foundation loads may be resisted by passive resistance on the sides of foundations and by friction on the base of the foundations. For foundations supported on native soils or on structural fill placed and compacted in accordance with our recommendations, the allowable frictional resistance may be computed using a coefficient of friction of 0.4 applied to vertical dead -load forces. The allowable passive resistance may be computed using an equivalent fluid density of 250 pounds per cubic foot (pef) (triangular distribution) if these elements are poured directly against compacted native soils or surrounded by structural fill. The structural fill should extend out from the face of the foundation element for a distance at least equal to theee tunes the height of the element and be compacted to at least 95 percent of the MDD. The above coefficient of friction and passive equivalent fluid density values incorporate a factor of safety of about 1.5. Construction Considerations If soft soil areas are present at the foundation subgrade elevation, the soft areas should be removed and replaced with structural fill. In such instances, the zone of structural fill should extend laterally beyond the footing edges a horizontal distance at least equal to the thickness of the fill. We recommend the condition of all footing excavations be observed by a representative from our firm to evaluate if the work is completed in accordance with our recommendations and that the subsurface conditions are as anticipated. RETAINING WALLS General We recommend that the proposed fill areas at the northwest corner of the site and along the north side of the new driveway be supported with Ultra Block walls. The Ultra Block walls should have a minimum of 18 inches embedment for the first course of blocks at the face of the wall. The upper 12 inches of the subgrade soil should be compacted to at least 95 percent of the MDD. At least 4 inches of crushed rock should be placed below the first course of blocks to protect the subgrade soil and distribute the wall load. The face of the wall should have a batter of l H:SV. For walls in excess of 5 feet high (two blocks), a woven reinforcing geotextile (WSDOT Standard Specifications Section 9-33.2(2)), will be needed to provide adequate wall stability. The geotextile should be located at a height of 5 feet above the bottom of the wall and extend horizontally from the face of the wall to 5 feet behind the back of the wail. Wall Drainage Positive drainage should be provided behind the Ultra Block walls by placing a 12-inch wide zone of gravel borrow behind the walls with a nonwoven geotextile filter fabric between the gravel borrow and the wall backfill. The non -woven geotextile filter fabric (WSDOT Standard Specifications Section 9-33.2(1), Moderate Survivability) should be wrapped to protect the top and bottom of the gravel borrow (WSDOT Standard Specifications Section 9-03.14(1)). Approximately I2 inches of on -site silty soil should be placed above the zone of gravel borrow to reduce the surface water infiltration behind the wall. File No 0186-673-00 Page 9 GwENGINEERS� .February 22, 2006 A 4-inch minimum diameter perforated drain pipe should be placed at the bottom of the zone of gravel borrow. We recommend using either heavy -wall solid pipe (SDR-35 PVC) or rigid corrugated polyethylene pipe (ADS N-12, or equal) for the collector pipe. We recommend against using flexible tubing for wall drain pipe. The pipe should be laid with a minimum slope of one-half percent and discharge to a suitable on -site disposal location. The pipe installations should include cleanouts to allow for future maintenance. Permanent drainage systems should intercept surface water runoff at the top and/or bottom of cut and fill slopes to prevent it from flowing in an uncontrolled manner across the wall. SITE DRAINAGE AND INFILTRATION We recommend that the ground surface be sloped to drain away from the proposed substation. Pavement surfaces should be sloped such that surface water runoff is collected and routed to suitable discharge points. We understand that stormwater at the site will be infiltrated using infiltration trenches that will be located either at the southwest corner or on the east side of the site. The trenches are anticipated to be Iocated 2 to 4 feet below the ground surface. The City of Renton requires that stonnwater be handled in accordance with the King County Surface Water Design Manual, and based on this manual and the results of our infiltration testing, we recommend a design infiltration rate of 5 inches per hour. Per the requirements of the Surface Water Design Manual, the infiltration facilities must be performance tested after construction to demonstrate capacity. PAVEMENT RECOMMENDATIONS Subgrade Preparation We recommend the subgrade soils in new pavement areas be prepared and evaluated as described in the "Earthwork" section of this report. We recommend the upper 12 inches of the existing subgrade soils be compacted to at Ieast 95 percent of the maximum dry density per ASTM D 1557 prior to placing pavement section materials- If the subgrade soils are loose or soft, it may be necessary to excavate the soils and replace them with structural fill. Asphalt Concrete Pavements New pavement sections for the driveways should conform to the PSE standard cross-section which consists of 3 inches of CIass %2 inch, PG 58 hot mix asphalt over at least i'/2 inches of crushed surfacing top course over at least 9 inches of base course aggregate. The crushed surfacing top course should meet the requirements of Section 9-03.9(3) of the 2006 WSDDT Standard Specifications, and the base course should conform to the PSE base course aggregate specification (1275,1310). The crushed surfacing base course and top course should be compacted to at least 95 percent of the maximum dry density prior to the placement of the asphalt concrete. We recommend that proofrolling of the compacted base course be observed by a representative from our firm prior to paving. Soft or yielding areas observed during proofrolling may require over -excavation and replacement with compacted structural fill. File No. 0186-673-00 Page 10 G W ENG IN E E R5� February 22, 2006 LIMITATIONS We have prepared this report for the exclusive use of Paget Sound Energy and their authorized agents for the President Parse Substation project in Renton, Washington. Within the limitations of scope, schedule and budget, our services have been executed in accordance with generally accepted practices in the field of geotechnical engineering in this area at the time this report was prepared. No warranty or other conditions, express or implied, should be understood. Any electronic form, facsimile or hard copy of the original document (email, text, table, and/or figure), if provided, and any attachments are only a copy of the original document. The original document is stored by GeoEngineers, Inc. and will serve as the official document of record. Please refer to Appendix C, Report Limitations and Guidelines for Use for additional information pertaining to use of this report. REFERENCES International Code Council, 2003, "International Building Code." King County Department of Natural Resources, 2005, "King County, Washington, Surface Water Design Manual." Mullineaux, D.R., 1965, United States Geologic Survey, "Geologic Map of the Renton Quadrangle, King County, Washington," Geologic Quadrangle Map GQ-405. U.S. Geological Survey —National Seismic Hazard Mapping Project — Interactive Deaggregations. URL: &Wl lleg i n t. cr. MWs. go v/e q/h t rn llde yZg m 1. html Washington State Department of Transportation, 2006, "Standard Specifications for Road, Bridge and Municipal Construction." File No. 0186-673-00 Page 11 G Eo ENGI N EE R February 22, 2006 9 9 O ! - t�� SST STRE ' 22ND ST O'. '. - � NE - -`drrlf � ST - $ •'- � 1, :- J' :' SE P1�IY ' � 5 -.., S '3t 'w:• � S`(' 1K �` !� R y, t�o9 w z 27(10 � � � iti� �, S� ) . __�4 :. � ' - "'E nn k § I s; tigTTL.ST r r PARK a h YtSY. - � � � t G - a 1 K[ II7Y cx -.- �N` ti Y filS1Y � -i �L ' •� � �•; 4TH _ ST ilE ark Pk R ] 4 W u 1E i7i11 ST LrplCis .. J-i _ r: � 12TR . ST ME ++ i 21N �ST Nr n% TM t1 ".itIffill W - ttr •,� li s 1DTH Il o r a I24TH ST ST 7u P t pc,�C � i,'l Fj�tipy+ W 45i)"x 4 SE 1281 IOOif CDS-4t� C�j b ' i +' K �' SE 1291fI ST 1R`RIYFI��q�. ti ;�4 � 1� � $E �r `[ �'fw: �L3iTx Ze X 51 Y p 37 I36TH Roo jj��'�,.- Lii`-4 k` 'Y' 0101a k�L 'F� Si ]mll 4 1ns'f �__)�� . .• ° Y .yl�[ - �Sy � C lI LdZI�} Si' � f YL'3 S �C .` -i" ram{, WE S 2000 0 2000 Feet Vicinity Map PSE President Park Substation Renton, Washington Reproduced with permission granted byT'HOMAS DROS. MAPS. This map is copyrighted by THONiAS BROS, MAPS- It is � E4 E NG I N E E R5� Figure 1 unlawful to copy or reproduce all or any part thereof, whether for personal use or resale, without permission. 0 CV Li I r] n ED c0 0 d a U O O n to w co 0 a a Ld w GEDENGINEERS APPENDIX A FIELD EXPLQRATIDNS r Ywir APPENDIX A FIELD EXPLORATIONS GENERAL Subsurface conditions were explored at the site by completing two test pits (TP-1 and TP-2) and six hand explorations (HA-1 through HA-6) outside the existing substation_ The test pits were excavated by Custom Backhoe on January 12, 2006, and three hand explorations were completed by GeoEngineers the same day. Three additional hand explorations were completed by GeoEngineers on February 1, 2006 to complete infiltration tests. In addition to these explorations completed outside the existing substation, eighteen hand explorations were completed inside the substation on January 12, 2006, primarily for evaluating potential environmental liabilities. The locations of the explorations were estimated in the field by measuring distances from site features through taping/pacing. The approximate exploration locations are shown on the Site Plan, Figure 2. Exploration elevations were estimated based on a topographic map provided by Puget Sound Energy dated December 15, 2005 that was used for our Site Plan. TEST PITS The test pits were excavated using a rubber -tired baekhoe. The test pits were continuously observed by a geotechnical engineer from our firm who examined and classified the soils encountered, obtained representative soil samples, observed groundwater conditions, and prepared a detailed log of each test pit. Soils encountered in the test pits were visually classified in general accordance with the classification system described in Figure A-1. A key to the exploration log symbols is also presented in Figure A-1. The logs of the test pits are presented in Figures A-2 and A-3. The logs reflect our interpretation of the field conditions and the results of laboratory testing and evaluation of samples. They also indicate the depths at which the soil types or their characteristics change, although the change might actually be gradual. The test pits were backfilled with the excavated soils and compacted to the extent practical with the bucket of the excavator. The fill will not behave as structural fill and will likely need to be recompacted during construction of the substation. HAND AUGER EXPLORATIONS The hand explorations were completed using a manually operated sampling auger. The auger bucket is approximately 4 inches in diameter and 12 inches long and is extended into the ground using a series of 3-feet rods. The auger was advanced into the soil by hand. The hand augers were completed by an environmental scientist or geotechnical engineer from our firm who examined and classified the soils encountered, obtained representative soil samples, observed groundwater conditions, and prepared a detailed log of each hand auger. The logs of the six hand auger explorations outside the substation are presented. in Figures A4 to A-9. The eighteen hand auger explorations completed inside the substation are summarized in Table A-1. GROUNDWATER CONDITIONS Observations of groundwater conditions were made during the explorations. The groundwater conditions encountered during the explorations are presented on the logs. Groundwater conditions observed during the explorations represent a short term condition and may or may not be representative of the long term groundwater conditions at the site. Groundwater conditions recorded on the logs should be considered approximate. File No. 0186-673-00 Page A -I GMENruVEER February22, 2006 TABLE A-1 SOIL DESCRIPTIONS AND FIELD SCREENING RESULTS PRESIDENT PARK SUBSTATION RENTON, WASHINGTON PUGET SOUND ENERGY PROJECT NO. 0186-673-00 Sample Identification' Date Sampled Sample Depth (feet bgs)z Water Sheen3 ScreeningSoil Description Chemical Aanalyslsa Hand Auger Soli Samples B-1 01/12/06 0.5 NS Surface Gravel — 01/12/06 1.0 NS Gray silty fine to medium sand with occasional gravel — 01 /12J06 2.0 NS Gray silty fine to medium sand with occasional gravel — 01/12J06 3.0 NS Gray silty fine to medium sand with occasional gravel — 5-2 01/12/06 0.5 NS Surface Gravel — 01/12/06 1.0 NS Red -Brown Silt with occasional gravel — 01/12/06 2.0 NS Red -Brown Silt with occasional gravel — 01/12106 3.0 NS Gray -Brown silty medium sand with occasional gravel Submitted B-3 01/12106 0.5 NS Surface Gravel — 01112/06 1.0 NS Red -Brown silty fine sand with occasional gravel — 01/12/06 2.0 NS Red -Brown silty fine sand with occasional gravel — 01 /12106 3.0 NS Gray silty medium sand with occasional fine gravel -- B-Q 01/12/06 0.5 NS Surface Gravel -- 01112/06 1.0 NS Red -Brawn silty fine sand with occasional gravel — 01/12/06 2.0 NS Red -Brown silty fine sand with occasional gravel — 01 /12/06 3.0 NS Gray silty medium to course sand and tine gravel — B-5 01/12/06 0.5 NS Surface Gravel -- 01/12/06 1.0 NS Gray silty fine to coarse sand with occasional gravel — 01/12/06 2.0 NS Gray silty fine to coarse sand with occasional gravel — 01/12/06 3.0 NS Gray silty fine to coarse sand with occasional gravel — B'6 OVUM 0.5 NS Surface Gravel — 01/12/06 1.0 NS Gray sil fine to coarse sand with occasional gravel Submitted 01/12J06 2.0 NS Gray sil fine to coarse sand with occasional gravel — 01112J06 3.0 NS I Gray silty fine to coarse sand with occasional gravel _ Notes appear on page 3 File No, 0186-573-00 February 2Z 2006 GeoEngineers TABLE A-1 (Page 2 of 3) Sample Identification' Date Sampled Sample Depth (feet bgse Water Sheen Screening Sall Description Chemical Analysls¢ Hand Auger Soil Samples (continued) 5-7 01/12/06 0.5 NS Surface Gravel _ 01112/06 1.0 NS Gray -Brown silty fine to coarse sand with occasional gravel — 01112/06 2.0 NS Gra)-Brown silty fine to coarse sand with occasional gravel 01/12/06 3.0 NS Gray -Brown silty fine to coarse sand with occasional gravel — B-g 01/12/06 0.5 NS Surface Gravel — 01/12/06 1.0 NS Gray silty fine to coarse sand with occasional gravel — 01/12/06 2.0 NS Gra)(_:0ty fine to coarse sand with occasional gravel — 01112/06 3.0 NS Gray silty fine to coarse sand with occasional gravel _ 5-9 01112/06 0.5 NS Surface Gravel Submitted 01/12/06 1.0 NS Gray silty fine to coarse sand with occasional ravel — 01/12/06 2.0 NS Gray silty fine to coarse sand with occasional gravel — 01/12/06 3.0 NS Brown silty fine to medium sand with occasional gravel _ B-10 01112/06 0.5 NS Surface Gravel — 01/12/06 1.0 NS Gray silty fine to coarse sand with occasional gravel — 01/12/06 2.0 NS Gray silty fine to coarse sand with occasional gravel — 01/12106 3.0 NS Brown silty fine to medium sand with occasional gravel — B-11 01/12/06 0.5 NS Surface Gravel — 01/12/06 1,0 NS Gray silty fine to coarse sand with occasional gravel — 01/12/06 2.0 NS Gray silty fine to coarse sand with occasional gravel — 01/12106 3.0 NS Brown silty fine to medium sand with occasional gravel — B-12 01/12106 0.5 SS Surface Gravel Submitted 01/12/06 1.0 N$ Gray silty fine to coarse sand with occasional gravel — 01/12106 2.0 NS Gray sil fine to coarse sand with occasional gravel -- 01/12/06 3.0 NS Brown silty fine to coarse sand with occasional gravel — B-13 01/12106 0.5 NS Surface Gravel 01/12/06 1.0 N5 Gray silty fine to coarse sand with occasional gravel — 01/12106 2.0 NS Gray silty fine to coarse sand with occasional gravel — 01/12106 3.0 NS Gray silty fine to coarse sand with occasional gravel — Notes appear on page 3 File No. 0186-673-00 February 22, 2006 GeoEnglnears TABLE A-1 (Page 3 of 3) Sample Identification' Date Sampled I Sample Depth (feet bgs)'2 17ater Sheen Screening 1 Soil Description Chemical Analy9186 Hand Auger SolI Samples (continued B-14 B-15 01/12/06 0.5 NS Surface Gravel _ 01/12/06 1.0 SS Black si!ty fine to coarse sand with gravel _ 01/12/06 2.0 NS Brown silty fine to coase sand with occasional ravel — 01/12/06 01/12/06 3.0 0.5 NS HS Brown silty fine to coase sand with occasional gravel Surface Gravel _ _ 01/12/06 1.0 HS Gray silty fine to coarse sand with occasional gravel _ 01/12/06 2.0 HS Brown silty fine to medium sand with occasional aravel Submitted 01/12/06 3.0 HS Wood board covering power conduit at 2.5 feet bgs B-16 01112106 0.5 NS Surface Gravel _ 01/12/06 1.0 NS Gray silty fine to coarse sand with occasional gravel _ 01/12/06 2.0 NS Gray silty fine to coarse sand with occasional gravel _ 01/12/06 3.0 NS Gray silty fine to coarse sand with occasional gravel _ B-17 01/12/06 0.5 MS Surface Gravel Submitted 01/12/06 1.0 SS Black sit fine to coarse sand with gravel _ 01/12/06 2.0 NS Red silty fine to medium sand with occasional gravel _ 01 /12106 2.5 NS Red silty fine to medium sand with occasional gravel _ B-18 01/12/06 1.0 NS Surface Gravel 01/12/06 2.0 NS Gra silty_fine to coarse sand with gravel _ 01/12/06 3.0 NS Gray silty fine to coarse sand with gravel _ 01/12/06 4.0 NS Gray silty fine to coarse sand with gravel _ Notes: ' Approximate sample locations are shown in Figure 2, Z Sample depths were recorded as depth beneath ground surface, 3 Water sheen testing is a qualitative field screening method used to evaluate the potential presence of petroleum related contamination. Field screening methods are 4 Grab samples were obtained from the borings to describe soil conditions in general accordance with ASTM guidelines. 5Polychlorinated biphenyis (PCB) analyzed using EPA method 8082 and/or mineral oil -range hydrocarbons analyzed using Ecology Method NWTPH-Dx with sulfuric -- = not tested NS = no sheen, SS = sli ht sheen, MS = moderate sheen, HS =heavy sheen. REDM:WW188673Y)OT-inale1418667300RTsb19A-1 jUs File No. 0186-673-00 February 22, 2006 GeoEngineers SOIL CLASSIFICATION CHART MAJOR DIVISIONS SYMBOLS TYPICAL DESCRIPTIONS GRAPH LETTER CLEAN o o� Gw wELL�#=ADED GRAVELS. GRAYEL- =AND MDCTURES GRAVEL GRAVELS AND GRAVELLY SOILS SATL[CR Sa FNE� o°o° D D �P POORLY{iRAMDGIRAYELS. GRAVEL. swo mmTuRES COARSE GRAINEp SCALS MORE TwW sos aFR F� GRhVELS 1MTH FINES a GM S LTY GRAVELS.GRAVEL-SAND- SILTMWrURE5 + CtAYEYGPoWELAGRAVEL •sN7D- CLAY IADnDREa RETAINED ON No. ASIEVE a "1O1'rt CLEAN SANDS SW WELL -GRADED SANDS, GRAVELLY SANDS MORE THAN 50% SAND SP POORLY43MDEDSANDS. SAND RETAMEDORND. SIEVE AND SANDY SOILSGRAVELLY MMIORNOF " SANDS yytTH FINES SILTY SANDS, BAND - SILT MD7URES MARE Tliw SO% of CDARSE R FRACON PASSING NO SIEVE gPPRECMDI£AAIOVIR Foeq se CLAYEY SANDS. SAND -CLAY MU RES ML W ORc IC SILTS. ROCK FLOMR. Ta c LArEY sii. VIrTN 611GNT PLAST-- FINE GRAINED SILTS AND LEL SAS DTIy NM IT CLAYS CL W ORGANIC CLAY$ OF LOW TO MEDIUM PLASTN;nY, GRAVELLY CLAY$, sMOY CLAYS, SILTY CLAYS, LEAN CLAYS QL ORGANIC SILTS AND ORGANIC AN siITY CLAYS OF LOW PLASTIOITY SOILS MORE nSO% Mw PASSING NO.20O I I ( I MH OM OR CA ODs VL�SOI LAMS L* SIEVE f t:ri-i pIY CLAYS OF FMFf AND uWDLIMIT CLAYS GREATER THAN 50 off CRGANIC CLAYSANDSATSOF MEDW4 TO NKi17 PLASTIGRY HIGHLY ORGANIC SOILS FIT PEAT. HUMUS. BNNLIP SOILS WRH MlGH ORGANIC CONTENTS NOTE: Multiple symbols are used to indicate bordertine or dual soil classifications Samoler Svmbol Descriptions ■ 2A-Inch I.D. split barrel A Standard Penetration Test (SPT) ® Shelby tube ® Piston Direct -Push ® Bulk or grab Bloweount Is recorded for driven samplers as the number of blows required to advance sampler 12 Inches (or distance noted). See exploration log for hammer weight and drop. A'P' Indicates sampler pushed using the weight of the drill rig. ADDITIONAL MATERIAL SYMBOLS SYMBOLS TYPICAL DESCRIPTIONS GRAPH LETTER CC Cement Concrete AC Asphalt Concrete CR Crushed Bock! Quarry Spalls TS TopsoiV Forest Duff/Sod Measured groundwater level In exploration, welt or pilezorneter T Groundwater Observed at tkne of exploration Perched water observed at time of exploration TF Measured free product In well or plawmetar Stratlaraphic Contact Duct contact between soil strata or geologic units /Gradual change between soil strata or geologic units ,_•___ Approxknate location of soil strata change within a geologic soil unit Laboratory I Field Tests %F Percent fines AL Atberberg limits CA Chemical analysis CID Laboratory compaction bast Cs Consolidation test DS Direct shear HA Hydrometer analysis MC Moisture content MD Moisture content and dry density OC Organic corrtent PM Permeability or hydraulic conductivity PP Pocket penatrnrneter SA Sieve analysis TX Trlaxial compression UC Unconfined compression VS Vane shear Sheen Classification NS No Visible Sheen SS Slight Sheen MS Moderate Sheen HS Heavy Sheen NT Not Tested NOTE: The reader must refer to the discussion in the report text and the logs of explorations for a proper understanding of subsurface conditions. Descriptions on the logs apply only at the specific exploration Locations and at the time the explorations were made; they are not warranted to be representative of subsurface conditions at other locations or times. KEY TO EXPLORATION LOGS GWENGINEER� FIGUREA-1 Date Excavated: 01/12/06 Logged by: IB2 Equipment: Rubber -tire Backhoe Surface Elevation (ft)• 407 vroiect: VS#= Vresldent kiark Substation GEOENGINEER Pro Project Location: Renton, Washington a Figure Project Number: 4156-673-00 Sheetet 17 of or 1 Date Excavated: 01/12/06 Logged by; TB2 Equipment: Rubber -tire Backhoe Surface Elevation (fl)- 412 vroleci: r-ar- rresiaens rarr-auusiauon G EO E N G I N E E R rJ /J/ Project Location: Renton, Washington Figure A-3 �� Project Number: 0186-673-00 sheet 1 of t I Date Excavated: 01/12/06 togged by: TB2 Equipment: Hand Auer Surface Elevation (ft)' 412 rroject: rresiuenL rarK �uvsiallUn G EO E N G I N E E R Project Location: Renton, Washington Figure A-4 Project Number: 0186-673-00 Sheet t or 1 Date Excavated: 01/12/06 Logged by: TB2 Equipment: Hand Auger Surface Elevation (ft), 412 Date Excavated: 01/12/06 Logged by: TB2 Equipment: Hand Auger Surface Elevation (ft)- 408 i J0 Z MATERIAL. DESCRIPTION e OTHER TESTS cc m u AND NOTES a•- a•' wD t]mE a a 1= r ±iou IL0 eE m 00 tla t) 0 0 v3 U 0— SM Brown silty fine to medium sand with gravel and trace roots and organic matter (loose, moist) Probes l to 2 feet SM Brownish gray silty fine to coarse sand with gravel and occasional Probes 2 to 4 inches cobbles (medium dense, moist) t IU-I-11 l I I MC=12% 2 1f I.: I I I I I SA; MC = 15% Hand auger completed at 4 feet No groundwater seepage observed No caving observed Refusal on dense sail and gravel 5 u 10---J } Notes: See Figure A-1 for explanation of symbols. The depths on the hand auger logs are based on an average of measurements across the hand auger and should be considered accurate to 0.5 foot_ LOG OF HAND AUGER HA-3 Project: PSE President Park Substation G W E N G I N E E R Project Location: Renton, Washington Figure A-6 Project Number: 0186-673-00 Sheet t of t Date Excavated: 02/01/06 Logged by: T)32 Equipment: Hand Anger - Surface Elevation (ft)- 413 o :� `m n Fz z MATERIAL DESCRIPTION OTHER TESTS t AND NOTES m d1 LLI Q CL.m C. E C- E L �� d n no f ? ro try co r7 J t3 V] t3 0 Brown silty fine to medium sand with occasional gravel and trace roots and organic matter (loose, moist) (fill) SM Brownish gray silty fine to medium sand with occasional gravel and cobbles (loose to medium dense, moist) 10 sm Cray silty fine to medium sand with gravel (medium dense to dense, moist) 5 Hand auger completed at 5 feet No groundwater seepage observed No caving observed 0 ca W c� a c� 0 n 05 s a z M m m 0 's r V d No es: See Figure A-1 for explanation of symbols- oThe z depths on the hand auger logs are based on as average ofineasuremeots across the hand auger and should be considered accurate to 0.5 foot LOG OF HAND AUGER HA-4 PSE President Park Substation GWENGINEER��rProject: Project Location: Renton, Washington Figure A-7 Project Number. 0186-673-00 sheet 4 of Date Excavated: 02/01/06 Equipment: Hand Auger Logged by: TB2 Surface Elevation (ft)- 412 G EO E N G I N E E R Project Location: Renton, Washington Figure A-8 Project Number 0186-673-00 sheet I or I Date Excavated: 02/01/06 Logged by: TB2 Equipment: Hand Auger Surface Elevation (tt)' 412 rfUJeUL. rJC rIC7wClfi rdlA ODUSIGLFUII G Ea E N G I N E E R Project Location: Renton, Washington Figure A-9 Project Number: 0186-673-00 Sheet 1 of I GE4ENGiNEER� APPENDIX B LABORATORY TESTING APPENDIX B LABORATORY TESTING GENERAL Soil samples obtained from the explorations were transported to our laboratory and examined to confirm or modify field classifications, as well as to evaluate index properties of the soil samples. Representative samples were selected for laboratory testing consisting of the determination of the moisture content, percent fines (material passing the U.S. No. 200 sieve), and grain size distribution (sieve analysis). The tests were performed in general accordance with test methods of the ASTM or other applicable procedures. The sieve analysis results are presented in Figure B-1. The results of the moisture content and percent passing the U.S. No. 200 sieve determinations are presented at the respective sample depth on the exploration logs in Appendix A. MOISTURE CONTENT TESTING Moisture content tests were completed in general accordance with ASTM D 2216 for representative samples obtained from the explorations. The results of these tests are presented on the exploration logs in Appendix A at the depths at which the samples were obtained. PERCENT PASSING U.S. NO. 200 SIEVE Selected samples were "washed" through the No. 200 mesh sieve to determine the relative percentages of coarse and fine-grained particles in the soil. The percent passing value represents the percentage by weight of the sample finer than the U.S. No. 200 sieve. These tests were conducted to verify field descriptions and to determine the fines content for analysis purposes. The tests were conducted in general accordance with ASTM D 1140, and the results are shown on the exploration logs at the respective sample depths. SIEVE ANALYSES Sieve analyses were performed on selected samples in general accordance with ASTM D422 to determine the sample grain size distribution. The wet sieve analysis method was used to determine the percentage of soil greater than the U.S. No. 200 mesh sieve. The results of the sieve analyses were plotted, classified in general accordance with the Unified Soil Classification System (USCS), and are presented in Figure B-1. File No 0186-673-00 PageB-I GMENGINEERLr/ll February 22, 2006 0186-673-00 TB2 : CTS : jvj 1-19-06 (Sieve.ppQ n U.S, STANDARD SIEVESIZE m 3" 1.5" 314" 3/8" 44 # 10 #20 440 060 # 100 9200 0 loo- m z G1 = so z 70 m m m 60 LA z 60 a0 30 U i W 20 a 10 (n 0 < 1000 100 10 1 0.1 0.01 0.001 m „ z GRAIN SIZE IN MILLIMETERS n C M rn T M to COBBLES GRAVEL SAND SILT OR CLAY m COARSE FINE ICOARSEI MEDIUM FINE C r N SYMBOL EXPLORATION NUMBER DEPTH ft SOIL CLASSIFICATION TP-1 6 Brownish gray silty fine to medium sand (SM) ❑ TP_2 g Gray silty fine to medium sand with grave! (SM) 49 HA-2 4 Gray silty fine to medium sand with gravel (SM) . HA-3 3.6 Brownish gray silty fine to coarse sand with gravel (SM) GEOENGlNEERL APPENDIX REPORT LIMITATIONS AND GUIDELINES FOR USE APPENDIX C REPORT LIMITATIONS AND GUIDELINES FOR USE' This appendix provides information to help you manage your risks with respect to the use of this report. GEOTECHNICAL SERVICES ARE PERFORMED FOR SPECIFIC PURPOSES, PERSONS AND PROJECTS This report has been prepared for the exclusive use of Puget Sound Energy and their authorized agents. This report may be made available to other members of the design and construction team for review. This report is not intended for use by others, and the information contained herein is not applicable to other sites. GeoEngineers structures our services to meet the specific needs of our clients. For example, a geotechnical or geologic study conducted for a civil engineer or architect may not fulfill the needs of a construction contractor or even another civil engineer or architect that are involved in the same project. Because each geotechnical or geologic study is unique, each geotechnical engineering or geologic report is unique, prepared solely for the specific client and project site. Our report is prepared for the exclusive use of Puget Sound Energy and their authorized agents. No other party may rely on the product of our services unless we agree in advance to such reliance in writing. This is to provide our firm with reasonable protection against open-ended liability claims by third parties with whom there would otherwise be no contractual limits to their actions_ Within the limitations of scope, schedule and budget, our services have been executed in accordance with our Agreement with Puget Sound Energy and generally accepted geotechnical practices in this area at the time this report was prepared. This report should not be applied for any purpose or project except the one originally contemplated. A GEOTECHNICAL ENGINEERING OR GEOLOGIC REPORT 1S BASED ON A UNIQUE SET OF PROJECT -SPECIFIC FACTORS This report has been prepared for the President Park Substation in Renton, Washington. GeoEngineers considered a number of unique, project -specific factors when establishing the scope of services for this project and report. Unless GeoEngineers specifically indicates otherwise, do not rely on this report if it was: • not prepared for you, • not prepared for your project, • not prepared for the specific site explored, or • completed before important project changes were made. For example, changes that can affect the applicability of this report include those that affect: • the function of the proposed structures; • elevation, configuration, location, orientation or weight of the proposed structures; • composition of the design team; or • project ownership. If important changes are made after the date of this report, GeoEngineers should be given the opportunity to review our interpretations and recommendations and provide written modifications or confirmation, as appropriate. DevOoped based on material provided by ASFE, Professional Firms Practicing in the Geosciences; www.asfe.org. File No. 0186-673-00 Page C-1 GEoENGINEER , February 22, 2006 SUBSURFACE CONDITIONS CAN CHANGE This geotechnical or geologic report is based on conditions that existed at the time the study was performed. The findings and conclusions of this report may be affected by the passage of time, by manmade events such as construction on or adjacent to the site, or by natural events such as floods, earthquakes, slope instability or groundwater fluctuations. Always contact GeoEngineers before applying a report to determine if it remains applicable. MOST GEOTECHNICAL AND GEOLOGIC FINDINGS ARE PROFESSIONAL OPINIONS Our interpretations of subsurface conditions are based on field observations from widely spaced sampling locations at the site. Site exploration identifies subsurface conditions only at those points where subsurface tests are conducted or samples are taken. GeoEngineers reviewed field and laboratory data and then applied our professional judgment to render an opinion about subsurface conditions throughout the site. Actual subsurface conditions may differ, sometimes significantly, from those indicated in this report. Our report, conclusions and interpretations should not be construed as a warranty of the subsurface conditions. GEOTECHNICAL ENGINEERING REPORT RECOMMENDATIONS ARE NOT FINAL Do not over -rely on the preliminary construction recommendations included in this report. These recommendations are not final, because they were developed principally from GeoEngineers' professional judgment and opinion. GeoEngineers' recommendations can be finalized only by observing actual subsurface conditions revealed during construction- GeoEngineers cannot assume responsibility or liability for this report's recommendations if we do not perform construction observation. Sufficient monitoring, testing and consultation by GeoEngineers should be provided during construction to confirm that the conditions encountered are consistent with those indicated by the explorations, to provide recommendations for design changes should the conditions revealed during the work differ from those anticipated, and to evaluate whether or not earthwork activities are completed in accordance with our recommendations. Retaining GeoEngineers for construction observation for this project is the most effective method of managing the risks associated with unanticipated conditions. A GEOTECHNICAL ENGINEERING OR GEOLOGIC REPORT COULD BE SUBJECT TO MISINTERPRETATION Misinterpretation of this report by other design team members can result in costly problems. You could lower that risk by having GeoEngineers confer with appropriate members of the design team after submitting the report. Also retain GeoEngineers to review pertinent elements of the design team's plans and specifications. Contractors can also misinterpret a geotechnical engineering or geologic report. Reduce that risk by having GeoEngineers participate in pre -bid and preconstruction conferences, and by providing construction observation - DO NOT REDRAW THE EXPLORATION LOGS Geotechnical engineers and geologists prepare final boring and test pit logs based upon their interpretation of field logs and laboratory data. To prevent errors or omissions, the logs included in a geotechnicaI engineering or geologic report should never be redrawn for inclusion in architectural or other design drawings. Only photographic or electronic reproduction is acceptable, but recognize that separating logs from the report can elevate risk. File No. 0186-673-00 Page C-2 G EoE NG IN EE Et February 22, 2006 GIVE CONTRACTORS A COMPLETE REPORT AND GUIDANCE Some owners and design professionals believe they can make contractors liable for unanticipated subsurface conditions by limiting what they provide for bid preparation. To help prevent costly problems, give contractors the complete geotechnical engineering or geologic report, but preface it with a clearly written letter of transmittal. In that letter, advise contractors that the report was not prepared for purposes of bid development and that the report's accuracy is limited; encourage them to confer with GeoEngineers and/or to conduct additional study to obtain the specific types of information they need or prefer. A pre -bid conference can also be valuable. Be sure contractors have sufficient time to perform additional study. Only then might an owner be in a position to give contractors the best information available, while requiring them to at least share the financial responsibilities stemming from unanticipated conditions. Further, a contingency for unanticipated conditions should be included in your project budget and schedule. CONTRACTORS ARE RESPONSIBLE FOR SITE SAFETY ON THEIR OWN CONSTRUCTION PROJECTS Our geotechnical recommendations are not intended to direct the contractor's procedures, methods, schedule or management of the work site. The contractor is solely responsible for job site safety and for managing construction operations to minimize risks to on -site personnel and to adjacent properties. READ THESE PROVISIONS CLOSELY Some clients, design professionals and contractors may not recognize that the geoscience practices (geotechnical engineering or geology) are far less exact than other engineering and natural science disciplines. This lack of understanding can create unrealistic expectations that could lead to disappointments, claims and disputes. GeoEngineers includes these explanatory "limitations" provisions in our reports to help reduce such risks. Please confer with GeoEngineers if you are unclear how these "Report Limitations and Guidelines for Use" apply to your project or site. GEOTECHNICAL, GEOLOGIC AND ENVIRONMENTAL REPORTS SHOULD NOT BE INTERCHANGED The equipment, techniques and personnel used to perform an environmental study differ significantly from those used to perform a geotechnical or geologic study and vice versa. For that reason, a geotechnical engineering or geologic report does not usually relate any environmental findings, conclusions or recommendations; e.g., about the likelihood of encountering underground storage tanks or regulated contaminants. Similarly, environmental reports are not used to address geotechnical or geologic concerns regarding a specific project. BIOLOGICAL POLLUTANTS GeoEngineers' Scope of Work specifically excludes the investigation, detection, prevention or assessment of the presence of Biological Pollutants. Accordingly, this report does not include any interpretations, recommendations, findings, or conclusions regarding the detecting, assessing, preventing or abating of Biological Pollutants and no conclusions or inferences should be drawn regarding Biological Pollutants, as they may relate to this project. The term "Biological Pollutants" includes, but is not limited to, molds, fungi, spores, bacteria, and viruses, and/or any of their byproducts. If Client desires these specialized services, they should be obtained from a consultant who offers services in this specialized field. Fife No. 0186-673-00 Page C-3 GEOENGINEERi. February22, 2006 City of Renton President Park Substation Storm Drainage Report Prepared for: PUGET SOUND ENERGY P.O. Box 90868 Bellevue, WA 98009 Prepared by: DAVID EVANS AND ASSOCIATES, INC. 415 - 1 18th Avenue SE Bellevue, WA 98005-3518 (425) 519-6500 PSEN0000-0054 April 2006 DEyE4� � GI p fi RQr /V/V V'3 APB 2 4 20OR '4jFCE1V D City of Renton President Park Substation Storm Drainage Report Prepared for: PUGET SOUND ENERGY P.()_ Box 90868 Bellevue, WA 98009 Prepared by: DAVID EVANS AND ASSOCIATES, INC. 415 - 1 1 Sth Avenue SE Bellevue, WA 98005-3518 (425) 519-6500 PSEN0000-0054 April 2006 EXPIRES 4/2/ NE 12TH T N.T.S. 900 NE 9TH ST w z w 405 Z w a z O_ NE 6TH ST NE 4TH ST SITE ■ VICINITY MAP 0 King County Building and Land Development Division TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Project Owner C Address 1�. ec,5 . Ba 1tL4 r Phone ./ - Project Engineer BcK-c-y TSB Company TAWtO =-VAAS A ASSQr-lraVs Address Phone M - S t1- 6 S� s, Q Subdivision Q Short Subdivision Q Grading 0 Commercial 0 Other rL e- Community ! Drainage Basin [] River [] Stream Q Critical Stream Reach Q Depressions/Swaies Q Lake Q Steep Slopes Q Lakeside/Erosion Hazard Slopes % 4, 15 Q Addilionai SheetsAitatched Page 1 of 2 Project Name 1~ G r Location Township Range S Section Project Size AC_L.,<D Upstream Drainage Basin Size- AC _ Q DOF/G HPA Q Shoreline Management Q COE 404 Q Rockery Q DOE Dam Safety Q Structural Vaults Q FEMA Floodplain Q Other Q COE Wetlands Q HPA Floodplain Wetlands Seeps/Springs High Groundwater Table Groundwater Recharge Other Erosion Potential Erosive Velocities C. M Page 2of2 King County Building and Land Development Division TECHNICAL INFORMATION REPORT (TIR) WORKSHEET REFERENCE LIMITATION/SITE CONSTRAINT [] Ch, 4 - Downstream Analysis 0 0 0 0 F-1 Additional Sheets Attatched PART 9 ESC REQUIREMENTS MINIMUM ESC REQUIREMENTS MINIMUM ESC REQUIREMENTS DURING CONSTRUCTION FOLLOWING CONSTRUCTION C� Sedimentation Facilities Stabilize Exposed Surface [� Stabilized Construction Entrance Remove and Restore Temporary ESC Facilities Q Perimeter Runoff Control [ Clean and Remove All Silt and Debris a Ciearing and Grading Restrictions 0 Ensure Operation of Permanent Facilities C Cover Practices Flag Limits of NGPES Construction Sequence Other Other 0 Grass Lined Channel = Tank M Infiltration Pipe System 0 Vault [] Depression Open Channel 0 Energy Dissapator 0 Flow Dispersal E71 Dry Pond Wetland 0 Waiver Wet Pond 0 Stream Regional Detention Method of Analysis Compensation/Mitigation of Eliminated Site Storage Brief Description of System Operation 2c -C c�R�, L Facility Related Silo Limitations Reference FaclHty Limitation 0 Cast in Place Vault El Other 0 Retaining Wall E 1 Rockery > 4' High 0 Struclural on Steep Slope = Additional Sheets Attatched Nvur . I or a civil engineer under my supervision have visited the site_ Actual site conditions as observed were incorporated into this worksheet and the attatchments. To the best of my knowledge the information provided here is accurate. 0 Drainage Easement [] Access Easement 0 Native Growth Protection Easement 0 Tract 0 Other S;gr.,&Dah TABLE OF CONTENTS VICINITY MAP TECHNICAL INFORMATION REPORT (TIR) WORKSHEET I. PROJECT OVERVIEW 1 2. CONDITIONS AND REQUIREMENTS SUMMARY 2 Core Requirements Discussions 3. INFILTRATION TRENCH ANALYSIS AND DESIGN 4 Id 4. CONCLUSION 5 5. SPECIAL REPORTS AND STUDIES 6 APPENDIX A. Existing Site Conditions B. Proposed Site Conditions C. Soil Map and Legend D. King County Isopluvials E. Portion of Geotechnical Report PROJECT OVERVIEW Existing Site Conditions The proposed site is located at 475 Union Ave NE in City of Renton, more generally in a portion of the Southeast Quarter of the Southeast Quarter of Section 9, Township 23 North, Range 5 East, W.M., in King County, Washington. See Vicinity Map. The site is approximately 1.02 acres and is currently used as a .Puget Sound Energy Substation known as "President Park Substation". The existing equipment of this substation is located in the middle of the site and is surrounded by a seven foot high chain link fence with 5' gravel shoulder around the outside of the existing fence. "There is an additional fenced area of approximately 300 sq. ft. for cell phone equipment. This area is located on the east side of the site and is attached to the outside of the substation fence. The cell site equipment is connected to a wooden cell tower. The outside perimeter of the 5' gravel shoulder is surrounded by vegetation. A mowed lawn is located on the east side of the site adjacent to Union Ave NE. The only access to the substation is via an existing approximately 12' wide asphalt driveway located on the southeast corner of the site from Union Ave NE_ The fenced substation area is generally flat and drains from west to east. It is located on top of a small hill and slopes down on all four sides with an approximately 3:1 slope. (See Appendix A. Existing Site Conditions Map) Proposed Site Conditions Puget Sound Energy is proposing to remove and demolish the existing electric and cell equipment, chain link fence, asphalt driveway and overhead and underground lines, for lowering and regarding the substation pad for new equipment. The new equipment will include transformers, electric towers and various electric components. An area approximately 3000 sq. ft. will be surrounded by spill prevention and containment curb (SPPC curb) where the transformer will be installed. The site will be lowered an average of 3.0 feet and the size of the equipment pad will be increased by approximately 1,400 sq. ft. The final grade of the new substation pad will be generally level as the existing pad. The existing ground under the new gravel base will be graded at 0.5% slope to the west. The pad will be fenced with 10 foot high chain link fence on all sides and surrounded by 5' gravel shoulder. Two gates will be installed on the east side of the substation facing Union Ave NE. Two 18' wide asphalt driveways will also be constructed to connect to Union Ave NE_ One gate will be installed on the west side of substation to access the infiltration trench for maintenance. "These driveways will be periodically utilized by Puget Sound Energy service trucks for re -construction, service and maintenance of the substation and its equipment. The cell phone equipment site will also be re -constructed at the same location after the construction of the substation. (See Appendix B, Proposed Site Conditions Map) 2. CONDITIONS AND REQUIREMENTS SUMMARY Section 4-6-030 of the City of Renton Municipal Code and. the King County Surface Water Management Design Manual (KCSWDM), 1990 Edition were used to determine the runoff control requirements. See Technical Information Report (TIR) Worksheet and actual impervious area calculation below. Total Proposed Impervious Proposed Impervious area (gravel) — 19,670 sq. ft. Proposed Impervious area (asphalt) = 4,678 sq. ft. Total Existing Impervious Existing Impervious area (gravel) = 18,251 sq. ft. Existing Impervious area (asphalt) = 1,974 sq. ft. Net Increase in Impervious area (gravel and asphalt) = 4,123 sq. ft. Per KCSWDM, Chapter 1.1.1, the addition of less than 5,000 sq. ft. of new impervious surface is not subject to drainage review and requirements. Even though this site is not subject to drainage requirements the Core requirements will be discussed below. P:%p\PSEN0000005410600INFOTCIStorm report.doc Core Requirement #] : Discharge at the Natural Location The majority of the storm surface runoff will be maintained as sheet flow across the substation pad from east to west. Some of the storm water is anticipated to be infiltrated on site for the fact that the existing soils have good infiltration rate. (See Appendix E, Soil Report). Core Requirement #2: Offsite Analysis The majority runoff from the site is via the two driveways. After storm surface runoff leaves the driveways and enters Union Ave NE it will continue flowing north along the flow line of the existing curb and gutter for approximately 160 LF to enter an existing catch basin. Then the flow goes northeast via an 8" pipe into a storm manhole. From there the flow is via a 24" pipe continuing north. That is the end of the offsite analysis. The site was visited on March 1, 2006; the weather was windy, overcast and no rain. There are no sign of any erosion or visible drainage problems to the north, south, west and along the frontage of the site to the first catch basin where the runoff flows into. The on -site landscape area is fairly well maintained and the lawn is well cared for. The northwest corner of the site was overgrown with brushes and disturbed by a backhoe used for soil investigation and the northeast comer is also overgrown with brushes. Core Requirement #3: Flow Control This site created less than 5,000 sq. ft. of new impervious area and therefore flow control is not required. On the other hand, the project site soils have good infiltration rate test results (See Appendix E, Soil Report); therefore an on -site infiltration trench will be constructed to control the storm water from the 2898 sq. ft. SPCC curb enclosed area. The infiltration trench will be constructed at the southwest corner of the site in the vicinity of the infiltration test pit no. HA-5. The infiltration trench will be 30' long x 1 I' wide x 3.5' deep with 5 rows of 12" perforated pipe to optimize the infiltration. (See Section 3 for Infiltration Trench Analysis and Design for details) An overflow conveyance will be constructed for added protection in case of emergency. Core Requirement 44: Conveyance System The only conveyance system will be the 8" storm pipe between the infiltration trench and the Catch basin within the SPCC curb area. Storm surface runoff will be sheet flow across the site for other areas. The storm surface runoff from the driveways will be collected by trench drain before exiting the right-of-way and route through a 4" pipe into the flow line of existing curb. Core Requirement #5: Erosion and Sediment Control Standard measures such as silt fence and stabilized construction entrance will be constructed prior to any construction to minimize erosion and sediment leaving the site. The substation pad is generally flat and with the landscaping areas on all sides the erosion potential is minimal. Core Requirement 4W Maintenance and Operations The infiltration trench shall be visually inspected every 6 months. Any debris and sediments over % ofthe perforated pipe shall be cleaned. The overflow pipe shall also be inspected to ensure the outlet is clear of debris. P:Ip1PSEN00000054106001NFOIEC1Sturm report.doc Core Requirement 47: Financial Guarantees and Liability Puget Sound Energy will provide construction bands and/or insurances as required by the City of Renton. Core Requirement #8: Water Quality This site created less than 5,000 sq. ft. of new impervious area and is not subject to runoff requirement; therefore water quality control is not required. 3. INFILTRATION TRENCH ANALYSIS ANI) DESIGN As discussed previously the project site is not subject to flow control, but an on -site infiltration trench to detain storm water from the SPCC curb area is proposed for added protection_ The development hydrograph was generated following the S.B.U.H. Methodology with Type 2, 24-hour rainfall distributions. For this analysis, 100% of the developed storm water will be detained in the infiltration trench_ The developed hydrographs were modeled using the curve number for impervious area. Using developed hydrographs, the infiltration trench was sized through the process of level pool routing using the StormShed software program. The total 24-hour precipitation rate of each storm event is as follows: P2yr — 2.00 in P10yr = 291 in P100yr = 3.90 in SPCC Curb area = 2,898 sq. ft. (0.066 Ac) CN number = 98 (impervious area) (See King County Isopluvials in Appendix D,) SPCC Curbed Area Event Summary: BasinID Peak Q Peak T Peak Vol Area Method Raintype Event ------- (cfs) (hrs) (ac-ft) ac /Loss spcc area 0.12 12.00 0.0098 0.07 SBUH/SCS TYPE2 2 yr spcc area 0.18 12.00 0.0147 0.07 SBUH/SCS TYPE2 10 yr spcc area 0.24 12.00 0.0202 0.07 SBUH/SCS TYPE2 100 yr Drainage Area: spec area Hyd Method: SBUH Hyd Loss Method: SCS CN Number Peak Factor: 484.00 SCS Abs: 0.20 Storm Dur: 24.00 hrs Intv: 10.00 min Area CN TC Pervious 0.0000 ac 98.00 0.00 firs Impervious 0.0660 ac 98.00 0.08 hrs Total 0.0660 ac Impervious CN Data: spcc area 98.00 0.0660 ac P:V,PSEN0000005410GOOINFOIECIStorm report _doc 3 Impervious TC Data: Flow type: Description: Length: Slope: Coeff: Travel Time Fixed None Entered 0.00 ft 0.00% 5.0000 5.00 min Control Structure ID: infiltration - Infiltration control structure Descrip: infiltration trench Start El Max El Increment 100.0000 ft 105.0000 ft 0.10 Infil: 3.50 inlhr Multiplier: 1.00 The Infiltration rate used is less than half of the actual infiltration rate for test pit no. HA-5 (7.7 in/hr) (See Appendix E, Soil Report) Node ID: infilvault Desc: Infiltration trench Start El: 100.0000 ft Max El: 108,0000 ft Contrib. Basin: Contrib. Hyd: Length Width Void Ratio 30.0000 ft 11.0000 ft 30.00 Bottom area only with infiltration Level Pool Summary 2 yr MatchQ—PeakQ— 0.1201 cfs Peak Out Q: 0.0267 cfs - Peak Stg: 101.22 ft - Active Vol. 120.31 cf 10 yr MatchQ=PcakQ= 0.1775 cfs Peak Out Q: 0.0267 cfs - Peak Stg: 102.19 ft - Active Vol: 217.23 of 100 yr MatchQ=PeakQ= 0.2395 cfs Peak Out Q: 0.0267 cfs - Peak Stg: 103.33 ft - Active Vol: 329.85 cf The size of infiltration trench = 30' long x I i' wide x 3.5' deep with 5 rows of 12" perforated pipes_ 4. CONCLUSION The characteristics from the existing site will be mostly intact and may even further improve after the construction of the new substation. The new chain link fence with vinyl slats and landscape vegetation surrounding the site will further enhance the screening to the adjacent properties. Lowering the substation pad will reduce the grade separation between the adjacent properties and also reduce the amount of runoff from the proposed site. Based on the KCSWDM no flow control is required, nevertheless, an infiltration trench is provided to hold and discharge some of storm water on -site. A trench drain for each driveway will also eliminate the storm surface runoff across the sidewalk providing a safer walk path for the pedestrian_ The proposed site improvements of the substation will not have any significant impact to the surrounding areas and will further enhance the substation. 5. SPECIAL REPORTS AND STUDIES See Appendix E for portion of Geotechnical r.nginecring Serviced Report prepared by GcoEngincers, Inc. on February 22, 2006_ P:Ip\PSEN00000054106001NFo1EC\Storm report doe ASP" i BLT✓G Alf J r� EAU S BRASS O15C ■1 A'YA' COW MA a® } � � IANOSCMEO � .e- -i� GRAVEL s� � wARnEar �--_ A9ART�Mr al S mtt AWR AWN EXISTING SITE CONDITIONS EXISTING GRAVEL AREA = 18,251 SOFT. EXISTING ASPHALT AREA = 1,974 SO -FT. WN 12- nA MARtmowl 5 m�: . g= � I a Im Rw Or• i IT 1 � � a �Q' Y EtLY . i➢9-u (*Avg-" R ,atra9. O i E E13l1410.69 D- �Z o Z Q r rff e fi rt-sae e' wuc Rr �0O C p�' � 0. alOeE76 � ,aa w9 FAEl6 EA.SEYUIT :� A�11 r b „ Dw POM 7 rpt / �.[ S EE 3Ag45..1 ppi I[ I� �7 p/� ° E-.sa.9 a rats 0 20 40 80 120 r� LEGEND GRAVES AREA ASPHALT AREA i APPENDIX A DAV I D E VA N S ANDASSOCIATES iirc. 415 - 118th Avenue SE owBellevue Washington 98005-3518 Phone: 425.519.6500 1 1 1 1 1 1 1 1 BLOCK RETAINING WALL no s MAZ use m ew com 'm t ji PROPOSED-' 'INrILTRATION TF ENCH -------- --- ca 600 CIO- :W1 PROPOSED A FOUNDATION 4-- (TYPICAL) --- --- - `I t jai 0 20 40 80 120 EA90"I BEf -CH 0 tw� LEGEND GRAVEL AREA t UK EASEM=w Ut ASPHALT AREA TRENCH RAIN ... . ..... .. SPCC CURB Is - PROPOSED SITE CONDITIONS PROPOSED GRAVEL AREA = 19,670 SQ.FT. PROPOSED ASPHALT AREA 4,678 SQ.FT. AREA INSIDE THE SPCC CURB = 2,898 SQ,FT, APPENDIX B DAVID EVANS ANoASSOCIATESINC. 415 - 11 8th Avenue SE Bellevue Washington 98005-3518 Phone: 425.519.6500 APPENDIX C KING COUNTY AREA, WAS) (RENTON QUADRANC AmC rssAWAH 12 MI. 10' 1 680000 FEET 1220O710" 703 V f �' AEDnOr r j!� i - -• • AMCi -; a an If ` rh � AgC AgC- •n • : 413• �~ 5 AgB An r •— `, l Tr$i lfr j: v . Ev8 ; ark.. . • j e' .8 }rgM B 3 ,. 424 •. •I. Pt 36 WA r SITE .. .......laaaoo r r � •� ! �� AgC FEET An rPrY FZAVEL A $tea n � Qx -' '15-� ' •i I .`. iY•„ ---- EvC --- jAkF sI� '•r P f.' I r� ..-• ems~ •.�,. art f¢II L- -_ ��_ � - � ! ...... •. 1 AkFot am ' ~�y[a ""-` : ---. AkF �+r�rr �y Pye �,Q, ' • �nfi f 11 EvB S AgC "' �----•-- � AkF I u• 1 rr Rh • r INa. � � •t n Py - a F a�1 r ; I. a te - k M w ,_ ___-� ��' p6q pNg .p 1 t' `u E o Pc C' ♦ A\�r AkF as�Ir % I A� Ne k AkF Parpy r N �^ + a 5f Y \C y • Al TBK' AgC EvC I I ! B` Age AkF M if 2 -- -- .77 •__- — °_ — # ~-° sa - 1-_ 6ML�' �_ BM 27r30rr A 6 ! _ I A9C AgC AgO .`- I AkF BMA 428 ! I AgB % 4mB I AgB _ -- crPE�rN1 AgC e ! 27 2 fA ur I 492 1 No �'40,po I i S Sk ! do AgC t • �! o i� B 470 Agg i T1x first capital letter is the initial one of t}ie soil name. A second capital letter, A, 3, C, D, E, at, F, indicates the class of slope_ Symbols without a slope letter are those of nearly level soils. SYMBOL NAML AgEl Alderwood gravelly sandy loam, 0 to 6 percent slopes Alderwood gravelly sandy loam, 6 to 15 percenr slopes AgD Alderwood gravelly samly loam, 15 ro 30 percent slopes AkF Alderwood and Kitsop soils, very steep A.8 Arents, Alderwood mate cl, 0 to 6 percent slopes • A-C: Arents, Alderwood material, 6 v0 15 percent slopes r An Arents, Everett material BeC $eausite gravelly sandy loam, 6 to 15 percent slopes gec) l3eausire gravelly sondy foam, 15 io 30 percent slopes 4.F Re .�. �. y..t-,ell.. --.tea.. 1-.. ._ 13h Rellingham silt loam Far Briscot silt loam Ru Rackley silt loam Cb Coastal Beaches Ea Earlmont silt loom Ed Edgewick fine sandy loam Ev8 Everett gravelly sondy loam, Oro 5 percent slopes EvC Everett gravelly sandy loam, 5 to 15 percent slopes EvD Everett gravelly sandy loam, 15 to 30 percent slopes EwC Everetr-Alderwood gravelly sandy hams, 6 to 15 percent slopes InA Indianola loamy fine sand, 0 to 4 percent slopes 3nC Indianola loamy fine sand, 4 to 15 percent slopes Inc) Indianola loamy Fine sand, 15 to 30 percent slopes Kp8 Kitsop silt loam, 2 to 8 pecceni slopes KPC Kitsop silt foam, 8 to 15 percent slopes KpD Kitsop silt laam, 15 to 30 percent slopes KsC Klaus gravelly loamy and, 6 to 1.5 percenr slopes Ma Mixed allavial land N.0 Neiltan very gra-�elly loamy sand, 2'o 15 percent slopes Ng Newberg silt loom Nk Nooksack silt loam No Norma sandy loam Dr Orcas pear Os Orldio silt loam OvC Qvoll gravelly loam, 0 to 15 percent slopes OvD Ovoll gravelly loam, 15 to 25 percent slopes OvF 0vall gravelly loam, 40 to 75 percent slopes Pc Pilchuck loamy Fine sand Pk Pilchuck fine sandy loam Flu Puget silry clay loam Py Puyallup Fine sandy loam RaC Rognar fine sandy loam, 6 to 15 percent slopes RaD Ragnor fine sandy loam, 15 to 25 percenr slopes RdC Rogtwr-Indianola association, sloping* RdE Rognor-Indianalo ossociotion, mrslerntely steep* Re Renton silt loam Rh River -ash So Salai silt loam Sh Samrramish silt loam Sk Seattle muck Sm Sho[car muck Sn Si silt loam So Snohomish silt Foom Sr Snohomish silt loam, thick surface variant Su Sultan silt loam T. Tukvrilo muck Ur Urban land W. WoodinviNe silt loam • The compasition of these units is more variable than that of the others in the area, but it has been controlled well enaugh to interpret For the expected usa of the soils. Insets, Sheet 4 APPENDIX D 0 1 2 3 4 5 S 7 B Mlles 1 . 300,000 1/90 _40 APPENDIX E 1 1 r 7 li GEOTECHNICAL ENGINEERING SERVICES ' PRESIDENT PARK SUBSTATION £ 5 RENTON, WASHINGTON l FEBRUARY 22, 2006 FOR PUGET SOUND ENERGY File No. 0186-673-00 Geotechnical Engineering Services President Park Substation Renton, Washington File No. 0186-673-00 February 22, 2006 Prepared for: Puget Sound Energy PO Box 90868, EST-04W Bellevue, Washington 98009-0868 Attention: Fred Lunki, PE Prepared by: GeoEngineers, Inc. Plaza 600 Building 600 Stewart Street, Suite 1700 Seattle, Washington 98101 (206)-728-2674 GeoEngineers, F164)ripiothy D. Bailey /GboterAnical Eno McFadden, PE, LEG TB2:JJM:jm:ta REDM:10101868731001Finals1018667300R.doc CopyrightQ 2006 by GeoEngineers, Inc. All rights reserved_ Disclaimer: Any electronic form, facsimile or hard copy of the original document (email, text, table, and/or figure), if provided, and any attachments are only a copy of the original document_ The original document is stored by GeoEngineers, Inc_ and will serve as the official document of record. File No. 0186-673-00 TABLE OF CONTENTS Page No. INTRODUCTION...........................................................................................................................................1 PROJECT DESCRIPTION.................•---.........------........-----...-•------..............................................---...............1 FIELD EXPLORATION AND LABORATORY TESTING..............................................................................1 FIELD EXPLORATIONS ......................................... -•--..................................---------............................1 LABORATORYTESTING................................................................................................................... 2 SITECONDITIONS....................................................................................................................................... 2 SURFACE CONDITIONS................................................................................................................... 2 GEOLOGY.................................................................. 2 SUBSURFACE CONDITIONS............................................................................................................2 GROUNDWATER CONDITIONS........................................................................................................ 3 INFILTRATION TESTING .............................................•--• ....................... 3 CONCLUSIONS AND RECOMMENDATIONS............................................................................................. 4 SUMMARY.......................•..................................................... .....4 EARTHQUAKE ENGINEERING.........................................................................................................4 EARTHWORK....................................................... .-------- --•--.........................................................---... 5 Excavation Considerations.................................................................•--•-.................................. 5 Clearingand Grubbing-----------------------------------------•---...........................-•---.............--....--.....------. 5 Subgrade Preparation.--------•................................................. ........... ......... 5 Erosion and Sedimentation Control ....................................................... .................................... 5 StructuralFill..............................................................................................................................6 Weather Considerations............................................................................................................ 7 TemporarySlopes..................................................................................................................... 7 PermanentSlopes..................................................................................................................... 8 SHALLOW FOUNDATIONS/ MAT FOUNDATIONS .......................................................................... 8 Allowable Bearing Pressure...................................................................................................... 8 Embedment........................................................................ Settlement-. 8 LateralResistance..................................................................................................................... 9 Construction Considerations ........................ ....... ......... ............................................................. 9 RETAININGWALLS ........................ .......... ................................................................... ..................... 9 General..................................................................................................................................... 9 WallDrainage................................................................... ......... 9 SITE DRAINAGE AND INFILTRATION ........................................................................................... 10 PAVEMENT RECOMMENDATIONS................................................................................................10 SubgradePreparation --------------------................................................---..- ............10 Asphalt Concrete Pavements..............................................................•-•---......................---•-•..10 LIMITATIONS......................................................................................... ...............................................11 REFERENCES....................................................................... 11 File No. 0166-673-00 Page i GMENGINEER� February 22, 2006 TABLE OF CONTENTS (CONTINUED) List of Tables Table 1. Infiltration Rate Test Results... Table 2- 2003 IBC Seismic Parameters List of Figures Figure 1. Vicinity Map Figure 2. Site Plan APPENDICES APPENDIX A —FIELD EXPLORATIONS ......................... Appendix A Table and Figures Table A-1. Soil Description and Field Screening Results Figure A-1. Key to Exploration Logs Figures A-2 and A-3. Log of Test Pits Figures A4 through A-9_ Log of Hand Augers APPENDIX B — LABORATORY TESTING ............... Appendix B Figures Figure B-1. Sieve Analysis Results APPENDIX C— REPORT LIMITATIONS AND GUIDELINES FOR USE ........................ Page No. 3 4 W106■ B-1 ...... C-1... C-3 File No. 0186-673-00 Page zi GWENdINEER .February 22, 2006 GEOTECHNICAL ENGINEERING SERVICES PRESIDENT PARK SUBSTATION RENTON, WASHINGTON FOR PUGET SOUND ENERGY INTRODUCTION This report summarizes the results of our geotechnical engineering services for the proposed improvements to the existing President Park substation. The substation is located at 475 Union Avenue NE, as shown on the Vicinity Map, Figure 1. The layout of the proposed improvements is shown on the Site Plan, Figure 2. Our geotechnical engineering services were completed in general accordance with our proposal dated January 5, 2006. Our scope of work includes: • Completing test pits and hand explorations at the site; • Completing infiltration tests at the site; • Completing laboratory testing on selected soil samples from the borings; • Providing geotechnical conclusions and recommendations for the proposed improvements; and • Preparing this report. GeoEngineers also completed environmental services which are summarized in a separate report, "Soil Characterization Services, President Park Substation, 475 Union Avenue NE, Renton, Washington'. PROJECT DESCRIPTION Our understanding of the project is based on our meeting with you and review of a preliminary site plan dated December 14, 2005 provided by PSE. We visited the site on January 2, 2006 to evaluate access considerations and develop an appropriate exploration plan. We understand that the existing substation will be demolished as part of this project. We also understand that the new substation will consist of two dead-end towers, a 115 kV transformer, and lightly loaded electrical equipment. The dead end towers will support three conductors, each with a 3 kip tension load at a height of 35 feet. The transformer will weigh up to 150 kips and be supported on a 12 foot by 14 foot by I foot thick mat. Other equipment includes a future structure for gas breaker and switches. This equipment will weigh about 17.5 kips and be supported on a 14 foot by 16 foot by 2.25 foot thick slab. The substation will have room for future expansion to include another transformer_ The proposed substation will be expanded to the west of the existing substation footprint. An additional driveway will be constructed from the substation east to Union Avenue NE. Some grading will be required to establish site grades, including removal of up to 4 feet of soil across the existing substation pad. Retaining walls will be required to support the fill at the northwest corner of the new substation fence as well as the north edge of the new access driveway. An infiltation facility will be used to manage storinwater from the substation. FIELD EXPLORATION AND LABORATORY TESTING FIELD EXPLORATIONS The subsurface conditions at the site were evaluated by completing two test pits, TP-1 and TP-2, to depths of $%2 feet below existing site grades. We also completed six hand explorations, HA -I to HA-6, to depths File No. 0186-673-00 Page I GWENGINEERS� February 21. 2006 of 4 to 5%s feet below existing site grades. The locations of the test pits and hand explorations are shown on the Site Plan, Figure 2. A detailed description of the field exploration program is presented in Appendix A. We also performed 18 hand explorations, B-1 to B-18, inside the substation as part of our soil characterization services for the environmental portion of this project. A summary table (Table A-1) of these explorations is included in Appendix A. LABORATORY TESTING Soil samples were collected during the exploration program and taken to GeoEngineers' laboratory for further evaluation. Selected samples were tested for the determination of moisture content, fines content (material passing the U.S. No. 204 sieve), and grain size distribution (sieve analysis). A description of the laboratory testing and the test results are presented in Appendix B or on the exploration logs, as appropriate. SITE CONDITIONS SURFACE CONDITIONS The site is located in a residential area with multifamily residential properties on the north, south, and west, and Union Avenue NE on the east. The site is currently occupied with an active substation, which includes a dead-end tower, a transformer, and other electrical equipment. The substation is surfaced with gravel and surrounded by a chain -link fence, and a cell tower is located east of the fence. The site is accessed from a paved asphalt concrete driveway off of Union Avenue NE. There is a 5 feet rockery at the southeast corner of the site on the neighboring property. Utilities at the site include underground power, communications and overhead power. The substation is approximately 10 to 13 feet higher than the surrounding area. The ground surface slopes up from the east, north, and west at about 2H:1V (horizontal to vertical) and the existing substation are located at the top of the slope in a fairly level area at about Elevation 413 feet. The residential properties to the south are built into the slope, so there is little grade change on the south side of the substation. Vegetation on the site includes grass, shrubs, and landscaping on the east side of the site and immediately adjacent to the substation fence. There are maple trees and blackberries on the west side of the site, and maple trees and brush in the northeast corner of the site. There is no landscaping inside the perimeter of the substation. There are no surface water features in the vicinity of the site. GEOLOGY Geologic information for the project area (Mullineaux, 1965) indicates that native surficial soils at the site are composed of glacial till. Glacial till commonly consists of a very compact, poorly sorted, non -stratified mixture of clay, silt, sand, gravel and cobbles. Till may include cobbles and large boulders. SUBSURFACE CONDITIONS Based on the explorations performed at the site, the subsurface conditions generally consist of fill and recessional outwash overlying dense glacial ti 11. On the west side of the site, we observed 2%2 to 3 feet of fill consisting of loose to medium dense silty sand with gravel. The fill was underlain by recessional outwash underlain by loose to medium dense silty File No_ 0186-673-00 Page 2 GEoENGINEER� February 22, 2006 sand with varying gravel content which generally extended to the depths explored, except in TP-2. in TP-2, glacial till consisting of dense silty sand with gravel was encountered below the recessional outwash at a depth of 7'/2 feet, and extended to the depth explored. In the area of the substation and to the east of the substation, we encountered loose to medium dense silty sand with varying gravel content which extended to the depths explored (3 to 5'/s feet below the ground surface). We interpret this silty sand to be regraded and native recessional outwash. We observed approximately 3 to 12 inches of gravel surfacing in and around the existing substation. GROUNDWATER CONDITIONS At the time of our exploration on January 12, 2005, the region had experienced 25 consecutive days with measurable precipitation. We observed groundwater at a depth of 6 feet below the ground surface (Elevation 401 feet) in TP-1. We observed that the soil became moist to wet at depths of about 4 feet in the explorations inside the substation, and we encountered groundwater at depths of 3'/z and 4 feet (Elevation 408.5 and 408 feet) in HA-1 and HA-2, respectively. During our subsequent explorations on February 1, 2006, which was during a drier period, we did not encounter groundwater in explorations HA-4 to HA-6, completed for the purpose of infiltration tests, although HA-6 was in an area where we observed groundwater on January 12. Based on our observations of groundwater conditions, we interpret that the groundwater and moisture encountered near Elevation 408 to 409 feet represents stonnwater perched on top of the dense glacial till encountered in TP-2. It appears that the groundwater at the site infiltrates and generally flows downhill to the northwest corner of the site. The ground at the northwest corner of the site was observed to be soft and wet. INFILTRATION TESTING The City of Renton requires that infiltration facilities be designed in accordance with King County regulations. King County requires infiltration testing, so we performed falling head infiltration tests at three of the exploration locations, HAA to HA-6 on February 1, 2006. The tests were performed in general accordance with the procedure described in Reference 6-A of the King County Surface Water Design Manual. To perform the falling head infiltration tests, 6-inch-inside-diameter PVC pipes were seated at least 6 inches into native soils at depths corresponding to the approximate elevation of the proposed infiltration facility. The infiltration rate tests were conducted by filling each pipe with approximately 6 inches of water above the native soil. The infiltration rates were measured for total water Ievel drops of 6 inches. The tests were repeated five times at each location and the results at each location were averaged. The results of the infiltration rate tests are presented on Table 1, together with the depths of each test. Table 1. Infiltration Rate Vest Results Rate (incheslhour) 409 8.1 407 � 7.7 Location: bn of ?est (feet) ElevaU Infiltration HA-4 HA-5 File No. 0186-673-00 Page 3 GMENGINEEAt February 22, 2006 CONCLUSIONS AND RECOMMENDATIONS SUMMARY A summary of the primary geotechnical considerations is provided below. The summary is presented for introductory purposes only and should be used in conjunction with the complete recommendations presented in this report. • The site is designated as seismic Soil Profile Type D per the 2003 International Building Code (IBC)- • On -site soils are suitable for re -use as structural fill during periods of dry weather and may be suitable during wet weather as well, provided they can be moisture conditioned to meet compaction requirements. If on -site soils cannot be adequately compacted during wet weather, imported gravel borrow should be used. • Substation equipment, including dead-end towers, can be supported on shallow foundations with an allowable bearing pressure of 3,500 psf, a passive resistance of 250 psf, and a base friction value of 0.4. We estimate total settlement on the order of Y2 to 1 inch. • The northwest corner and the new access drive extending to the northeast areas of the substation expansion can be supported using 2- or 3-block-high Ultra Block walls (5 to 7%a feet high). Reinforcing geotextile will be required for walls taller than 5 feet, on supporting sloping backfill. • New pavements for the driveways may consist of the standard PSE pavement section, with 3 inches of asphalt concrete over 10% inches of top and base course - Our specific geotechnical recommendations are presented in the following sections of this report. EARTHQUAKE ENGINEERING GeoEngineers evaluated the site for seismic hazards including liquefaction, lateral spreading, fault rapture and earthquake -induced slope instability. Our evaluation indicates that the site does not have liquefiable soils present and therefore also has no risk of liquefaction -induced lateral spreading. In addition, the site has a low risk of fault rupture or seismically -induced slope movement. We recommend the 2003 International Building Code (IBC) parameters for Site Class, short period spectral response acceleration (Ss), 1-second period- spectral response acceleration (SI), and Seismic Coefficients FA and Fv presented in Table 2. File No. 0186-673-00 February 22, 2006 Table 2. 2003 113C Seismic Parameters Page 4 GWENGINEERL EARTHWORK Excavation Considerations Fill, recessional outwash, and glacial till were observed in the explorations. We anticipate that these soils can be excavated with conventional excavation equipment, such as trackhoes or dozers. Cobbles were encountered in the soils at the site. While boulders were not observed in the explorations, they may also be encountered, and the contractor should be prepared to remove them where necessary. Clearing and Grubbing Removal and demolition of existing substation structures should include removal of foundation elements. Existing voids or new depressions created during site preparation should be cleaned of loose soil or debris and backfilled with structural fill. Trees, brush and other vegetation, including topsoil with roots, should be stripped and removed from areas where structural fill will be placed. The stripped material should be placed in landscaping areas or taken off -site for disposal. Subgrade Preparation In areas where structural fill is to be placed, the upper 12 inches of existing subgrade soils should be compacted and evaluated prior to fill placement through either probing or proof -rolling with heavy, rubber -tired construction equipment. Likewise, the exposed subgrade in the proposed foundation areas for structures and retaining walls should be evaluated after site grading is complete. Probing should be used to evaluate the subgrades where proof -rolling is not possible or if site grading takes place during wet weather. Soft zones noted during proof -rolling or probing should be excavated and replaced with compacted structural fill. Fill placed on existing slopes which are steeper than 5H:1V should be properly keyed into the native soil slope surface. This can be done by constructing the fill in a series of 6- to 8-foot wide horizontal benches cut into the slope. Bench surfaces should be constructed in accordance with Section 2-03.3(14) of the 2006 WSDOT Standard Specifications, and should be thoroughly compacted prior to placing the fill soils. Erosion and Sedimentation Control Potential sources or causes of erosion and sedimentation depend upon construction methods, slope length and gradient, amount of soil exposed and/or disturbed, soil type, construction sequencing and weather. The project impact on erosion -prone areas can be reduced by implementing an erosion and sedimentation control plan. The plan should be designed in accordance with applicable city and/or county standards. The plan should incorporate basic planning principles including: • Scheduling grading and construction to reduce soil exposure; • Retaining existing vegetation whenever feasible; • Revegetating or mulching denuded areas; • Directing runoff away from denuded areas; • Minimizing the length and steepness of slopes with exposed soils; • Decreasing runoff velocities; • Confining sediment to the project site; and • Inspecting and maintaining control measures frequently. File No. 0186-673-00 Page 5 GMENGINEERS February 22, 2006 We recommend that graded and disturbed slopes be tracked in place with the equipment running perpendicular to the slope contours so that the track marks provide a texture to help resist erosion and channeling. Some sloughing and raveling of slopes with exposed or disturbed soil should be expected. Temporary erosion protection should be used and maintained in areas with exposed or disturbed soils to help reduce the potential for erosion and reduce transport of sediment to adjacent areas. Temporary erosion protection should include the construction of a silt fence around the perimeter of the work area prior to the commencement of grading activities. Permanent erosion protection should be provided by re-establishing vegetation using hydroseeding and/or landscape planting. Until the permanent erosion protection is established and the site is stabilized, site monitoring should be performed by qualified personnel to evaluate the effectiveness of the erosion control measures and repair and/or modify them as appropriate. Provisions for modifications to the erosion control system based on monitoring observations should be included in the erosion and sedimentation control plan. Structural Fill Materials. Materials used to raise site grades, placed to support structures or pavements, or used for utility trench backfill is classified as structural fill for the purpose of this report. Structural fill material quality varies depending upon its use as described below: 1. On -site soils may be used as structural fill during dry weather. On -site soils may also be used during wet weather provided that they can be moisture conditioned to meet compaction specifications. If on -site soils cannot be moisture conditioned, imported gravel borrow (WSDOT Standard Specifications Section 9-03.14(1)) should be used. 2. Structural fill placed as crushed surfacing top course below pavements should conform to Section 9-03.9(3) of the 2006 W SDOT Standard Specifications. Pavement base course aggregate should conform to Puget Sound Energy Specification 1275.3110. 3. Structural fill placed as yard surfacing material should conform to Puget Sound Energy Specification 1275.1330 as described in the following table: US Si(Andard Sieve Size Percent.Passirig (by weight) 1'/2 inches 100 1 inch 90 to 100 % inch 0 to 15 _ 318 inch 0 to 5 Fill Placement and Compaction Criteria. Structural fill should be mechanically compacted to a firm, non -yielding condition. In general, structural fill should be placed in loose lifts not exceeding 8 to 10 inches in thickness. Each lift should be conditioned to the proper moisture content and compacted to the specified density before placing subsequent lifts. Structural fill should be compacted to the following criteria: 1. Structural fill placed below foundations, pavement areas or to establish yard grades should be compacted to at least 95 percent of the maximum dry density (MDD) estimated in accordance with American Society for Testing and Materials (ASTM) D 1557. Structural fill placed to form finished slopes should also be compacted to at least 95 percent of the MDD. 2. Structural fill placed behind retaining walls should be compacted to between 90 to 92 percent of the MDD estimated in accordance with ASTM D 1557. Hand operated compactors should be used within 5 feet behind the wall. File Na 0186-673-00 Page 6 GEGENGINEERi February 2Z 2006 3. Structural fill (including utility trench backfill) placed outside of areas where foundations, roadways, parking and yard areas are to be located should be compacted to at least 90 percent of the MDD estimated in accordance with ASTM D 1557. 4. Crushed rock base course placed as structural fill below pavements should be compacted to at least 95 percent of the MDD estimated in accordance with ASTM D 1557. We recommend that a representative from our firm be present during proof -rolling and/or probing of the exposed subgrade soils in structure and pavement areas prior to the placement of structural fill and also during the placement of structural fill. Our representative would evaluate the adequacy of the subgrade soils and identify areas needing further work, perform in -place moisture -density tests in the fill to evaluate if the work is being done in accordance with the compaction specifications, and advise on any modifications to procedures that may be appropriate for the prevailing conditions. Weather Considerations The native soils contain a sufficient percentage of fines (silt) and are moisture sensitive. When the moisture content of these soils is appreciably above the optimum moisture content, these soils become muddy and unstable, operation of equipment on these soils will be difficult, and it will be difficult to meet the required compaction criteria. Additionally, disturbance of these near surface soils should be expected if earthwork is completed during periods of wet weather. The wet weather season generally begins in October and continues through May in the Puget Sound region; however, periods of wet weather may occur during any month of the year. The optimum earthwork period for these types of soils is typically June through September. If wet weather earthwork is unavoidable, we recommend that: • Stockpiles of on -site soils that will be used as structural fill during wet weather be covered with plastic sheeting to protect them from rain. If on -site soils cannot be moisture conditioned to meet compaction requirements during wet weather, imported gravel borrow should be used as discussed previously. • The ground surface in and around the work area be sloped so that surface water is directed away from the work area. The ground surface should be graded such that areas of ponded water do not develop. Measures should be taken by the contractor to prevent surface water from collecting in excavations and trenches. Measures should be implemented to remove surface water from the work area. Temporary Slopes The soils encountered at the site are classified as Type C soil in accordance with the provisions of Title 296-155 WAC (Washington Administrative Code), Part N, `Excavation, Trenching, and Shoring." We recommend that temporary slopes in excess of 4 feet in height be inclined no steeper than 1'/2H:1 V. Flatter slopes may be necessary if localized sloughing occurs. For open cuts at the site we recommend that: • No traffic, construction equipment, stockpiles or building supplies be allowed at the top of cut slopes within a distance of at least 5 feet from the top of the cut. • Exposed soil along the slope be protected from surface erosion using waterproof tarps or plastic sheeting. • Construction activities be scheduled so that the length of time the temporary cut is left open is kept as short as possible. File No. 0186-673-00 Page 7 GEoENGINEERi February 22. 2006 + Erosion control measures be implemented as appropriate such that runoff from the site is reduced to the extent practical. Surface water is diverted away from the excavation_ The general condition of the slopes be observed periodically by a geotechnical engineer to confirm adequate stability - Since the contractor has control of the construction operations, the contractor should be made responsible for the stability of cut slopes, as well as the safety of the excavations. All shoring and temporary slopes must conform to applicable local, state and federal safety regulations. Permanent Slopes We recommend that permanent cut and fill slopes be constructed no steeper than 2H:1V. To achieve uniform compaction, we recommend that fill slopes be overbuilt slightly and subsequently cut back to expose properly compacted fill. To reduce erosion, newly constructed slopes should be planted or hydroseeded shortly after completion of grading. Until the vegetation is established, some sloughing and raveling of the slopes should be expected. This may require localized repairs and reseeding. Temporary covering, such as clear heavy plastic sheeting, jute fabric, loose straw or excelsior matting should be used to protect the slopes during periods of rainfall. SHALLOW FOUNDATIONS/ MAT FOUNDATIONS Allowable Bearing Pressure We recommend the substation equipment be supported on conventional spread footings or mat foundations bearing on either the native soils or on properly compacted structural fill placed over the native soils. The mat foundations and spread footings, where required, may be designed using an allowable soil bearing value of 3,500 pounds per square foot (psf). An allowable edge pressure of 4,000 psf may be used in the design of dead end tower foundations. The allowable soil bearing values apply to the total of dead and long-term live loads and may be increased by up to one-third for transient loads such as wind or seismic forces. A subgrade modulus of 200 pounds per cubic inch (pci) may be used for the design of mat foundations. Embedment In general, we recommend that the bottom of foundations be founded at least 18 inches below the lowest adjacent grade for frost protection. The foundation embedment depth may be reduced to 12 inches for small, lightly loaded footings where frost action will not affect equipment performance or an additional 6-inch thickness of non -frost susceptible gravel may be placed below the foundations to achieve an embedment of 18 inches. The gravel should meet the requirements of "yard surfacing material" presented above. Settlement Provided all loose soil is removed and the subgrade is prepared as recommended in the "Construction Considerations" section below, we estimate that the total settlement of shallow foundations will be on the order of/2 to 1 inch. Differential settlements are expected to be less than '/z inch. File No. 0186-673-00 Page 8 GEoENGINEER5� February 2Z 2006 Lateral Resistance Lateral foundation loads may be resisted by passive resistance on the sides of foundations and by friction on the base of the foundations. For foundations supported on native soils or on structural fill placed and compacted in accordance with our recommendations, the allowable frictional resistance may be computed using a coefficient of friction of 0.4 applied to vertical dead -load forces. The allowable passive resistance may be computed using an equivalent fluid density of 250 pounds per cubic foot (pef) (triangular distribution) if these elements are poured directly against compacted native soils or surrounded by structural fill. The structural fill should extend out from the face of the foundation element for a distance at least equal to three times the height of the element and be compacted to at least 95 percent of the MDD. The above coefficient of friction and passive equivalent fluid density values incorporate a factor of safety of about 1.5. Construction Considerations If soft soil areas are present at the foundation subgrade elevation, the soft areas should be removed and replaced with structural fill. In such instances, the zone of structural fill should extend laterally beyond the footing edges a horizontal distance at least equal to the thickness of the fill. We recommend the condition of all footing excavations be observed by a representative from, our firm to evaluate if the work is completed in accordance with our recommendations and that the subsurface conditions are as anticipated. RETAINING WALLS General We recommend that the proposed fill areas at the northwest corner of the site and along the north side of the new driveway be supported with Ultra Block walls. The Ultra Block walls should have a minimum of 18 inches embedment for the first course of blocks at the face of the wall. The upper 12 inches of the subgrade soil should be compacted to at least 95 percent of the MDD. At least 4 inches of crushed rock should be placed below the first course of blocks to protect the subgrade soil and distribute the wall load. The face of the wall should have a batter of 1H:5V. For walls in excess of 5 feet high (two blocks), a woven reinforcing geotextile (WSDOT Standard Specifications Section 9-33.2(2)), will be needed to provide adequate wall stability. The geotextile should be located at a height of 5 feet above the bottom of the wall and extend horizontally from the face of the wall to 5 feet behind the back of the wall. Wall Drainage Positive drainage should be provided behind the Ultra Block walls by placing a 12-inch wide zone of gravel borrow behind the walls with a nonwoven geotextile filter fabric between the gravel borrow and the wall backfill. The non -woven geotextile filter fabric (WSDOT Standard Specifications Section 9-33.2(i), Moderate Survivability) should be wrapped to protect the top and bottom of the gravel borrow (WSDOT Standard Specifications Section 9-03.14(1)). Approximately 12 inches of on -site silty soil should be placed above the zone of gravel borrow to reduce the surface water infiltration behind the wall. File No. 0186-673-00 Page 9 GEOENGINEERS February 22, 2006 A 4-inch minimum diameter perforated drain pipe should be placed at the bottom of the zone of gravel borrow. We recommend using either heavy -wall solid pipe (SDR-35 PVC) or rigid corrugated polyethylene pipe (ADS N-12, or equal) for the collector pipe. We recommend against using flexible tubing for wall drain pipe. The pipe should be laid with a minimum slope of one-half percent and discharge to a suitable on -site disposal location. The pipe installations should include cleanouts to allow for future maintenance. Permanent drainage systems should intercept surface water runoff at the top and/or bottom of cut and fill slopes to prevent it from flowing in an uncontrolled manner across the wall. SITE DRAINAGE AND INFILTRATION We recommend that the ground surface be sloped to drain away from the proposed substation. Pavement surfaces should be sloped such that surface water runoff is collected and routed to suitable discharge points. We understand that stormwater at the site will be infiltrated using infiltration trenches that will be located either at the southwest corner or on the east side of the site. The trenches are anticipated to be located 2 to 4 feet below the ground surface. The City of Renton requires that stormwater be handled in accordance with the King County Surface Water Design Manual, and based on this manual and the results of our infiltration testing, we recommend a design infiltration rate of 5 inches per hour. Per the requirements of the Surface Water Design Manual, the infiltration facilities must be performance tested after construction to demonstrate capacity. PAVEMENT RECOMMENDATIONS Subgrade Preparation We recommend the subgrade soils in new pavement areas be prepared and evaluated as described in the "Earthwork" section of this report. We recommend the upper 12 inches of the existing subgrade soils be compacted to at least 95 percent of the maximum dry density per ASTM D 1557 prior to placing pavement section materials, if the subgrade soils are loose or soft, it may be necessary to excavate the soils and replace them with structural fill. Asphalt Concrete Pavements New pavement sections for the driveways should conform to the PSE standard cross-section which consists of 3 inches of Class % inch, PG 58 hot mix asphalt over at least 1'/ inches of crushed surfacing top course over at least 9 inches of base course aggregate. The crushed surfacing top course should meet the requirements of Section 9-03.9(3) of the 2006 WSDDT Standard Specifications, and the base course should conform to the PSE base course aggregate specification (1275.1310). The crushed surfacing base course and top course should be compacted to at least 95 percent of the maximum dry density prior to the placement of the asphalt concrete. We recommend that proofrolling of the compacted base course be observed by a representative from our firm prior to paving. Soft or yielding areas observed during proofrolling may require over -excavation and replacement with compacted structural fill. File No. 0186-673-00 Page 10 GMENGINEERS February 22, 2006 LIMITATIONS We have prepared this report for the exclusive use of Puget Sound Energy and their authorized agents for the President Park Substation project in Renton, Washington. Within the limitations of scope, schedule and budget, our services have been executed in accordance with generally accepted practices in the field of geotechnical engineering in this area at the time this report was prepared. No warranty or other conditions, express or implied, should be understood. Any electronic form, facsimile or hard copy of the original document (email, text, table, and/or figure), if provided, and any attachments are only a copy of the original document. The original document is stored by GeoEngineers, fnc. and will serve as the official document of record. Please refer to Appendix C, Report Limitations and Guidelines for Use for additional information pertaining to use of this report. REFERENCES International Code Council, 2003, ".International Building Code_" King County Department of Natural Resources, 2005, "King County, Washington, Surface Water Design Manual." Mullineaux, D.R., 1965, United States Geologic Survey, "Geologic Map of the Renton Quadrangle, King County, Washington," Geologic Quadrangle Map GQ-405. U-S_ Geological Survey — National Seismic Hazard Mapping Project — Interactive Deaggregations. URL: hYR:I%gint. cr. usgs_ggv/eglhtml/deaggint. html Washington State Department of Transportation, 2006, "Standard Specifications for Road, Bridge and Municipal Construction." 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' yyA• C"'A, kF - vxi r x - � 5�,,�p f' S7 g� � N WE S 2000 0 2000 Feet Vicinity Map PSE President Park Substation Renton, Washington Reproduced with permission granted by THOMAS BROS. MAPS. This map is copyrighted by THOMAS BROS. MAPS. 1t is unlawful to copy or reproduce all or any part thereof, whether G E©E N G I N E E R Figure 9 for personal use or resale, without permission. ED 0 0 Y CD F- (fl Of GEOENGINEERS t, APPENDDC A FIELD EXPLORATIONS APPENDIX A FIELD EXPLORATIONS GENERAL Subsurface conditions were explored at the site by completing two test pits (TP-1 and TP-2) and six band explorations (14A-1 through HA-6) outside the existing substation. The test pits were excavated by Custom Backhoe on January 12, 2006, and three hand explorations were completed by GeoEngineers the same day. Three additional hand explorations were completed by GeoEngineers on February 1, 2006 to complete infiltration tests. In addition to these explorations completed outside the existing substation, eighteen hand explorations were completed inside the substation on January 12, 2006, primarily for evaluating potential environmental liabilities. The locations of the explorations were estimated in the field by measuring distances from site features through taping/pacing. The approximate exploration locations are shown on the Site Plan, Figure 2. Exploration elevations were estimated based on a topographic map provided by Puget Sound Energy dated December 15, 2005 that was used for our Site Plan. TEST PITS The test pits were excavated using a rubber -tired backhoe. The test pits were continuously observed by a geotechnical engineer from our firm who examined and classified the soils encountered, obtained representative soil samples, observed groundwater conditions, and prepared a detailed log of each test pit. Soils encountered in the test pits were visually classified in general accordance with the classification system described in Figure A-1. A key to the exploration log symbols is also presented in Figure A-1. The logs of the test pits are presented in Figures A-2 and A-3. The logs reflect our interpretation of the field conditions and the results of laboratory testing and evaluation of samples. They also indicate the depths at which the soil types or their characteristics change, although the change might actually be gradual. The test pits were backfilled with the excavated soils and compacted to the extent practical with the bucket of the excavator. The fill will not behave as structural fill and will likely need to be recompacted during construction of the substation. HAND AUGER EXPLORATIONS The hand explorations were completed using a manually operated sampling auger. The auger bucket is approximately 4 inches in diameter and 12 inches Iong and is extended into the ground using a series of 3-feet rods. The auger was advanced into the soil by hand. The hand augers were completed by an environmental scientist or geotechnical engineer from our firm who examined and classified the soils encountered, obtained representative soil samples, observed groundwater conditions, and prepared a detailed log of each hand auger. The logs of the six hand auger explorations outside the substation are presented in Figures A4 to A-9. The eighteen hand auger explorations completed inside the substation are summarized in Table A-1. GROUNDWATER CONDITIONS Observations of groundwater conditions were made during the explorations_ The groundwater conditions encountered during the explorations are presented on the logs. Groundwater conditions observed during the explorations represent a short term condition and may or may not be representative of the long term groundwater conditions at the site. Groundwater conditions recorded on the logs should be considered approximate. File No_ 0186-673.00 PageA-1 GMENGINEERS February .21, 2006 TABLE A-1 SOIL DESCRIPTIONS AND FIELD SCREENING RESULTS PRESIDENT PARK SUBSTATION RENTON, WASHINGTON PUGET SOUND ENERGY PROJECT NO.0186-673-00 Sample Identification'Sampled Date Sample Depth (feet bgs)2 Water Sheen' Screenin Soil Descriptlo64 Chemical Analysisa Hand Auger Soil Samples B-1 01/12/06 0.5 NS Surface Gravel — 01/12/06 1.0 NS GraX silty fine to medium sand with occasional gravel — 01/12/06 2.0 NS Gray silty fine to medium sand with occasional gravel -- 01/12/06 3.0 NS Gray silty fine to medium sand with occasional gravel -- 8-2 01/12/06 0.5 NS Surface Gravel — 01/12/06 1.0 NS Red -Brown Silt with occasional gravel -- 01/12/06 2.0 NS Red -Brown Silt with occasional gravel — 01/12/06 3.0 NS Gray -Brown silty medium sand with occasional gravel Submitted B-3 01/12106 0.5 NS Surface Gravel — 01/12/06 1.0 NS Red -Brown -silty fine sand with occasional gravel — 01/12/06 2.0 NS lied -Brown silty fine sand with occasional gravel — 01/12/06 3.0 NS Gray silty medium sand with occasional fine gravel -- B-4 01/12/06 0.5 NS Surface Gravel — 01/12/06 1.0 NS Red -Brown silty fine sand with occasional gravel — 01/12/06 2.0 NS Red -Brown silty fine sand with occasional gravel -- 01/12/06 3.0 NS Gray silty medium to course sand and fine gravel -. 8-5 01/12/06 0.5 NS Surface Gravel — 01112/06 1.0 NS Gray sil fine to coarse sand with occasional gravel — 01/12106 2.0 NS Gray silty fine to coarse sand with occasional 2ravel — 01/12/06 &0 NS Gray silty fine to coarse sand with occasional gravel — 8-6 01112/06 0.5 NS Surface Gravel — 01/12/06 1.0 NS Gray silty fine to coarse sand with occasional gravel Submitted 01/12/06 2.0 NS Gray silty fine to coarse sand with occasional gravel 01/12/06 1 3.9 1 NS Gray silty fine to coarse sand with occasional gravel — Notes appear on page 3 Fire No. 0186-673-00 February 22, 2006 GeoEnglneers TABLE A-1 (Page 2 of 3) Sample Identification Date I Sampled Sample Depth (feet bgs)= Water Sheen' Screening Soil Description' Chemical Analysis Hand Auger Soil Samples continued B-7 01/12/06 0.5 NS Surface Gravel — 01/12/06 1.0 NS Gray -Brown silty fine to coarse sand with occasional gravel — 01/12/06 2.0 NS Gray -Brown silty fine to coarse sand with occasional gravel — 01/12/06 3.0 NS Gray -Brown silty fine to coarse sand with occasional gravel _ B-6 01/12/06 0.5 NS Surface Gravel — 01/12/06 1.0 NS Gray silty fine to coarse sand with occasional gravel — 01/12/06 2.0 NS Gray silty fine to coarse sand with occasional 2ravel — 01/12/06 3.0 NS Gray silty fine to coarse sand with occasional gravel — B-g 01112J06 0.5 NS Surface Gravel Submitted 01/12/06 1.0 NS Gray sillfine to coarse sand with occasional gravel — 01/12/06 2.0 NS Gray si!ty fine to coarse sand with occasional gravel — 01/12/06 3,0 NS Brown silty fine to medium sand with occasional gravel — B-90 01/12/06 0.5 NS Surface Gravel — 01/12106 1.0 NS Gray silty fine to coarse sand with occasional gravel — 01112/06 2,0 NS Gray silty fine to coarse sand with occasional gravel — 01112/06 3.0 NS Brown silty fine to medium sand with occasional gravel — B-11 01/12/06 0.5 NS Surface Gravel — 01/12/06 1.0 NS Gray silty fine to coarse sand with occasional gravel — 01/12/06 2.0 NS Gray silty fine to coarse sand with occasional gravel — 01/12/06 3.0 NS Brown silty fine to medium sand with occasional gravel — B-12 01/12/06 0.5 SS Surface Gravel Submitted 01/12/06 1.0 NS Gray silty fine to coarse sand with occasional gravel — 01/12106 2.0 NS Gray silty fine to coarse sand with occasional gravel — 01/12/06 3.0 NS Brown silty fine to coarse sand with occasional gravel — B-13 0111V06 0.5 NS Surface Gravel — 01/12106 1.0 NS Gray silty fine to coarse sand with occasional gravel — 01/12/06 2.0 NS Gray silty fine to coarse sand with occasional gravel — 01/12/06 3.0 NS Gray silty fine to coarse sand with occasional gravel — Notes appear on page 3 File No. 0186-673-00 February 2Z 2006 GeoEnalneers TABLE A-1 (Page 3 of 3) Sample Date Sampled Sample Depth Water Sheen (feet bgs)z Screening Soil Description ChemicalIdentification/ Analysis6 Hand Auger SolI Samples (continued B-14 01/12/06 0.5 NS Surface Gravel 01112/06 1.0 SS Black silty fine to coarse sand with gravel — 01/12/06 2.0 NS Brown silty fine to coase sand vrith occasional gravel _ 01/12106 3.0 NS Brown silty fine to coase sand with occasional gravel _ 8-16 01/12106 0.5 HS Surface Gravel _ 01/12/06 1.0 HS Gray silty fine to coarse sand with occasional gravel -- 01/12/06 2.0 HS Brown silty fine to medium sand with occasional gravel Submitted 01/12/06 3.0 HS Wood board covering power conduit at 2.5 feet bgs _ B-16 01112/06 0.5 NS Surface Gravel _ 01/12/06 1.0 NS Gray sllty fine to coarse sand with occasional gravel — 01/12106 2.0 NS Gray silty fine to coarse sand with occasional gravel — 01/12/06 3.0 NS Gray silty fine to coarse sand with occasional gravel _ B-17 01/12/06 0.5 MS Surface Gravel Submitted 01/12/06 1.0 SS Black s0ty fine to coarse sand with gravel -- 01/12/06 2.0 NS Red silty fine to medium sand with occasional gravel - 01/12/06 2.5 NS Red silty fine to medium sand with occasional gravel — B-18 01/12/06 1.0 NS Surface Gravel 01/12/06 2.0 NS Gray silty fine to coarse sand with gravel — 01/12/06 3.0 NS Gray silty fine to coarse sand with gravel _ 01/12/06 4.0 NS Gray silty fine to coarse sand with gravel — Notes: 'Approximate sample locations are shown in Figure 2. 2 Sample depths were recorded as depth beneath ground surface. 3 Water sheen testing is a qualitative field screening method used to evaluate the potential presence of petroleum related contamination. Field screening methods are ° Grab samples were obtained from the borings to describe soil conditions in general accordance with ASTM guidelines. 5Polychlodnated biphenyls (PCB) analyzed using EPA method 8082 and/or mineral oil -range hydrocarbons analyzed using Ecology Method NWTPH-Dx with sulfuric -- = not tested NS = no sheen, 55 = slight sheen, MS = moderate sheen, HS = heavy sheen. REDM:1010186673WOVinals1U1868730ORTableA-1.xls File No. 0186-673-00 February 22, 2006 GeoEngineers SOIL CLASSIFICATION CHART MAJOR DMSIONS SYMBOLS TYPICAL. DESCRIPTIONS GRAPH LETTER Ct" 01 \P d �j`w WELL-G GRAVELS,GRAVEL- SAM MIR)AR E0 GRAVEL GRAVELS V AND GRAVELLY SOILSAWTH 00R oA No FNEM G O O O GP POORLrr,RADEDGRAVELS. GRAVEL -SAND MDnVRES GM sLTV GRAVELS,GRAVEL-SAND- CRANED GRAINI� SULS MORE TNAN W% OFCOMSESnTNIxTLIRES FRACTION CLAY MI%TLIRES RETAW-VONN0curErGRAVELsaRAYEL-SAND- CLEANSANDS S. 1NEll .RADE0 SANDS. GRAVELLY SANDS MORETHA9%% SAND Sp PRtY-GRADEDSANDS. cNAVELLY SAND RETAINED ON NO. mo SIEVE AND SANDY SOILS CLIME oA No FIMM SANDS mTH FINES SM SILTY SANDS, SAND -SILT MIX RES MORE TNAN SO% DR COARSE rRACTION PASSING NO. 4 SIEVE WPREGANE AMDVNT OF FNEFr SC CLAYEY SANDS, SAND -CLAY MRTV RLS INORGANIC SILYs ROGR FLOVR. 'LAYey SILTS...T PLA"rrY FINE GRAINED SILTS AND LESS T1rN so CLAYS CL INORGANIC CLAYS OF LOW TO MEMN PLASTICRY. GRAVELLY CL y cLA r Cur'' SILTY CLAYS, tL aRGANIC SRTSANDORSA SILTY CLAYS OF LOW PLASMITY SatS MORE THAN 501AI` PAWN q NO. 700 { MH INOFYGANtC 81LT8. MICACEOUS OR DLATONACEGUS SILTYSDILS SIEVE 1 f Zz CH INORGANIC CLAYS OF HIGH PLASTICITY SILTS AND LIOUDUAIn cursGREATEN THAN SO 4/EY ON ORGAM TO HtG FLASTr TY MERVM TO M(iN PLABTIOTFY LHIGHLY ORGANIC SOILS trr HUrAV5. 51NAMPeRGANIccGNTENrs FT ADDITIONAL MATERIAL SYMBOLS SYMBOLS TYPICAL DESCRIPTIONS GRAPH LETTER - CC grin• Cement Concrete AC Asphalt Concrete CR Crushed Rock/ Quarry 5palis :r Topsoill Forest Duff/Sod Measured groundwater level In exploration, well, or plezomater V Groundwater observed at time of exploration Perched water observed at tine of exploration IF Measured free product In well or plexometer Stiatitaraohic Contact Distinct contact between soil strata or geologic units Gradual change between soil strata or geologic units _ _ _ _ Approximate location of soil strata change within a geologic loll unit NOTE Multiple symbols are used to indicate borderline or dual soil classifications Laboratory I Field Tests Sampler §Mbol Descriptions %F Percent fines Atterberg Iknlfs ■AL 2A4nch I.D. split barrel CA Chemical analysis CP Laboratory compaction bast Standard Penetration Test (SPT) CS Consolidation test DS Direct shear ® Shelby tube HA Hydrometer analysis MG Moisture content ®Piston MD Moisture corderd and dry density OC Organic content Direct -Push PM Parrneability or hydraulic conductivity PP Pocket penetrometer ®Bulk or grab SA TX Sleve analysis Trhudat compression UC Unconfined compression VS Vane shear Blov=unt Is recorded for driven sam piers as tine number of blows required to advance sampler 12 inches (or Sheen Classification distance noted). See exploration log for harnrner weight and drop. SWt Sheen SSSS en A "P" Indicates sampler pushed using the weight of the MS Moderate sheen drill rig. KS Heavy Sheen NT Not Tested NOTE: The reader must refer to the discussion in the report text and the logs of expbratlans for a proper understanding of subsurface conditions_ Desaiptions on the logs apply only at the specific exploration locations and at the time the explorations were made; they are not warranted to be representative of subsurface conditions at other locations or times. I KEY TO EXPLORATION LOGS GEoENGINEER� FIGUREA-1 Date Excavated: 01/12/06 Logged by: TB2 Equipment Rubber -tire Backhoe Surface Elevation (ft)• 407 Project: PSE President Park Substation G EQ E N G I N E E R Project Location: Renton, Washington Figure A-2 Project dumber. 0986 673-00 Sheet 1 of 1 Date Excavated: 01/12/06 Logged by: TB2 Equipment: Rubber -tire Backhoe Surface Elevation (tt)- 412 o MATERIAL DESCRIPTION -14 OTHER TESTS m m m n n= nM m m AND NOTES 6 lJlm cd w `20 O� o0 co to c9� 0w I�U SM Brownish gray silty fine to medium sand with gravel and occasional cobbles (loose to medium dense) (fill) Probes 2 to 8 inches MC —15% 1D SM Brown silty fine to medium sand with gravel and tract roots and organic matter (loose, moist) Probes 4 to 12 inches %F=18;MC=15% 5 SP-SM Light brown fine to medium sandArith silt, gravel and occasional cobbles (medium dense, moist) 05 3 %F=10;MC=8% SM Gray silty fine to medium sand with gravel (dense, moist) Wacial.till) 4 J SA; MC = 11% Test pit completed at 8.5 feet No groundwater seepage observed No caving observed 14 Notes: See Figure A-1 for explanation of symbols. The depths on the test pit logs are based on an average of measurements across the test pit and should be considered accurate to Q 5 foot LOG OF TEST PIT TP-2 Project: PSE President Park Substation G W E N G I N E E R Project Location: Renton, Washington Figure A-3 Project Number 0186-673-00 Sheet T of I Date Excavated: 01/12/06 bogged by: TB2 Equipment: Hand Auger _ Surface Elevation (ft)• 412 z MATERIAL DESCRIPTION OTHER TESTS L m m o o tD AND NOTES — CL w❑ m W mCD of to W o C7 � 0 W 00 U 0 UP 3 inches gravel surfacin Sm Grta silt fine to medium sand with gravel and occasional cobbles med4m dense, moist to wet) 0 2 t IT 1,11 1 1 1 MC=12'/0 Hand auger completed at 4 feet Groundwater seepage observed at 3.5 feet No caving observed Unable to retrieve samples below 4.5 feet due to water r 10- Notes: See Figure A-1 for explanation of symbols_ The depths on the hand auger logs are based on an average of measurements across the hand auger and should be considered accurate to 0.5 foot. L LOG OF HAND AUGER HA-1 Project: PSE President Park Substation G W E N G 1 N E E Project Location: Renton, Washington Figure A-4 Project Number: 0186-673-00 sheet 1 of 1 Date Excavated: 01/12/G6 Logged by: TB2 Equipment: __ Hand Auger Surface Elevation (ft)- 412 Date Excavated: 01/12/06 Logged by: TB2 Equipment:. _ Hand Auger Surface Elevation (ft)' 448 1_vV WE I1^1�LJ /'1V Vl�fl [-iMw Project: PSE President Park Substation G EO E N G I N E E R Project Location: Renton, Washington Figure A-6 Project Number: 0186-673-04 sneer t ar 1 Date Excavated: 02/01/06 Lagged by: TB2 Hand Auger Surface Elevation ft - 413 Equipment:._ ( ) rrotect: rzpt a resiaeni rant ouosiauon GEOENGINEER� Project Location: Renton, Washington Pro � g i=igureA-7 Project Number: 0186-673-00 Sheet 1 of 1 Date Excavated: 02/01/06 Logged by: TB2 Equipment: Hand Auger Surface Elevation (ft): 412 rroject rar_ rresiaent rarK Ouv5tauvn G E4 E N G I N E E R Project Location: Renton, Washington Figure A-8 Project Number: 0186-673-00 Sheet 1 of 1 Date Excavated: 02/01/06 Logged by: TB2 Equipment: Hand Auger Surface Elevation (ft)- 412 Project: Pit President Park Substation G Eo E N G I N E ER Project Location: Renton, Washington Figure A-9 �� Project Number. 0186-673-00 sheet 1 of t GE4ENGINEERS APPENDIX B LABORATORY TESTING APPENDIX B LABORATORY TESTING GENERAL Soil samples obtained from the explorations were transported to our laboratory and examined to confirm or modify field classifications, as well as to evaluate index properties of the soil samples. Representative samples were selected for laboratory testing consisting of the determination of the moisture content, percent fines (material passing the U.S. No. 200 sieve), and grain size distribution (sieve analysis). The tests were performed in general accordance with test methods of the ASTM or other applicable procedures. The sieve analysis results are presented in Figure B-1. The results of the moisture content and percent passing the U.S. No. 200 sieve determinations are presented at the respective sample depth on the exploration logs in Appendix A. MOISTURE CONTENT TESTING Moisture content tests were completed in general accordance with ASTM D 2216 for representative samples obtained from the explorations. The results of these tests are presented on the exploration logs in Appendix A at the depths at which the samples were obtained. PERCENT PASSING U.S. No. 200 SIEVE Selected samples were "washed" through the No. 200 mesh sieve to determine the relative percentages of coarse and fine-grained particles in the soil. The percent passing value represents the percentage by weight of the sample finer than the U.S. No. 200 sieve. These tests were conducted to verify field descriptions and to determine the fines content for analysis purposes. The tests were conducted in general accordance with ASTM D 1140, and the results are shown on the exploration logs at the respective sample depths. SIEVE ANALYSES Sieve analyses were performed on selected samples in general accordance with ASTM D422 to determine the sample grain size distribution. The wet sieve analysis method was used to determine the percentage of soil greater than the U.S. No. 200 mesh sieve. The results of the sieve analyses were plotted, classified in general accordance with the Unified Soil Classification System (USCS), and are presented in Figure B-1. File No. 0186-673-00 Page E-1 GWENGINEER February 22, 2006 0186-673-00 TB2 : CTS : jvj 1-19-06 (Sleve.ppl) 1 ! 1 11 � !' IIIII■■■■11111i���.�1���I■■NIIIII■■■■IIIII■■N■IIIII■■■■ IIIII■■■IIIII■■■� �1>,.��1�■■IIIII■■■■IIIII■■■■IIIII■■■■ •, IIIII■■■■IIIII■■L��.:i:�y�i !�11111■■■■IIIII■■■�IIi11■■■N ;, IIIII■■■■IIIII■■■��Ill������i�:���■■■IIIII■�■■IIIII■■■■ IIIII■■■�11111■■i �11111�■l��IIIII�.!■NIIIII■■■■IIIII■■■� IIIII■■■IIIII■■■�►��111■■■� IIIII■►1■■IIIII■■■NIIIII■■■■ II1111■■M11111■■■=1111210 ii11I■■■NIIIII■■■■II111■■■M .. 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I1111■■■■IIIII■■■�11111■■■■ 1111■■■■I�aII■■■■IIIII■■■■ , Ii111■■■■IIIII■■■�11111■■■�11111■■■NIIIII■■■�I1111■■■N IIIII■■■■ IIIII■■■■IIIII■■■■ III■■■■IIIII■■■■ IIIi1■■■■ , IIIII■■■NIIIII■�■�11111■■■■ IIIN■■■IIIII■■■NIIIII■■■■ rrr 4rt r r r r r r� SYMBOL EXPLORATION DEPTH GEtA VEL SAND COBBLES SILT OR CLAY COARSE FINE COARSE MED1l1Ni FII�iE NUMBER ft SAIL CLASSIFICATION • TP-1 & Brownish gray silty fine to medium sand {SM) ❑ TP-2 8 Gray silty fine to medium sand with gravel (SM) � wy_Z q Gray silty fine to medium sand with gravel (SM) HA-3 3.5 Brownish gray silty fine to coarse sand with gravel (SM) GEOENGINEERS APPENDix C REPORT LIMITA TIONS AND GUIDELINES FOR USE APPENDIX C REPORT LIMITATIONS AND GUIDELINES FOR USE' This appendix provides information to help you manage your risks with respect to the use of this report. GEOTECHNICAL SERVICES ARE PERFORMED FOR SPECIFIC PURPOSES, PERSONS AND PROJECTS This report has been prepared for the exclusive Use of Puget Sound Energy and their authorized agents. This report may be made available to other members of the design and construction team for review. This report is not intended for use by others, and the information contained herein is not applicable to other sites. GeoEngineers structures our services to meet the specific needs of our clients. For example, a geotechnical or geologic study conducted for a civil engineer or architect may not fulfill the needs of a construction contractor or even another civil engineer or architect that are involved in -the same project. Because each geotechnical or geologic study is unique, each geotechnical engineering or geologic report is unique, prepared solely for the specific client and project site. Our report is prepared for the exclusive use of Puget Sound Energy and their authorized agents. No other party may rely on the product of our services unless we agree in advance to such reliance in writing. This is to provide our firm with reasonable protection against open-ended liability claims by third parties with whom there would otherwise be no contractual limits to their actions. Within the limitations of scope, schedule and budget, our services have been executed in accordance with our Agreement with Puget Sound Energy and generally accepted geotechnical practices in this area at the time this report was prepared. This report should not be applied for any purpose or project except the one originally contemplated. A GEOTECHNICAL ENGINEERING OR GEOLOGIC REPORT IS BASED ON A UNIQUE SET OF PROJECT -SPECIFIC FACTORS This report has been prepared for the President Park Substation in Renton, Washington. GeoEngineers considered a number of unique, project -specific factors when establishing the scope of services for this project and report. Unless GeoEngineers specifically indicates otherwise, do not rely on this report if it was: • not prepared for you, • not prepared for your project, • not prepared for the specific site explored, or • completed before important project changes were made. For example, changes that can affect the applicability of this report include those that affect: • the function of the proposed structures; • elevation, configuration, location, orientation or weight of the proposed structures; • composition of the design team; or • project ownership. If important changes are made after the date of this report, GeoEngineers should- be given the opportunity to review our interpretations and recommendations and provide written modifications or confirmation, as appropriate. 3 Developed based on material provided by ASFF, Professional Finns Practicing in the Geosciences; www_asfe.org . File No. 0186-673-00 Page C-1 GWENGINEER . February 22, 2006 SUBSURFACE CONDITIONS CAN CHANGE This geotechnical or geologic report is based on conditions that existed at the time the study was performed. The findings and conclusions of this report may be affected by the passage of time, by manmade events such as construction on or adjacent to the site, or by natural events such as floods, earthquakes, slope instability or groundwater fluctuations. Always contact GeoEngineers before applying a report to determine if it remains applicable. MOST GEOTECHNICAL AND GEOLOGIC FINDINGS ARE PROFESSIONAL OPINIONS Our interpretations of subsurface conditions are based on field observations from widely spaced sampling locations at the site. Site exploration identifies subsurface conditions only at those points where subsurface tests are conducted or samples are taken. GeoEngineers reviewed field and laboratory data and then applied our professional judgment to render an opinion about subsurface conditions throughout the site. Actual subsurface conditions may differ, sometimes significantly, from those indicated in this report. Our report, conclusions and interpretations should not be construed as a warranty of the subsurface conditions. GEOTECHNICAL ENGINEERING REPORT RECOMMENDATIONS ARE NOT FINAL Do not over -rely on the preliminary construction recommendations included in this report. These recommendations are not final, because they were developed principally from GeoEngineers' professional judgment and opinion. GeoEngineers' recommendations can be finalized only by observing actual subsurface conditions revealed during construction. GeoEngineers cannot assume responsibility or liability for this report's recommendations if we do not perform construction observation - Sufficient monitoring, testing and consultation by GeoEngineers should be provided during construction to confirm that the conditions encountered are consistent with those indicated by the explorations, to provide recommendations for design changes should the conditions revealed during the work differ from those anticipated, and to evaluate whether or not earthwork activities are completed in accordance with our recommendations. Retaining GeoEngineers for construction observation for this project is the most effective method of managing the risks associated with unanticipated conditions. A GEOTECHNICAL ENGINEERING OR GEOLOGIC REPORT COULD BE SUBJECT TO MISINTERPRETATION Misinterpretation of this report by other design team members can result in costly problems. You could lower that risk by having GeoEngineers confer with appropriate members of the design team after submitting the report. Also retain GeoEngineers to review pertinent elements of the design team's plans and specifications. Contractors can also misinterpret a geotechnieal engineering or geologic report. Reduce that risk by having GeoEngineers participate in pre -bid and preconstruction conferences, and by providing construction observation. ❑O NOT REDRAW THE EXPLORATION LOGS Geotechnical engineers and geologists prepare final boring and test nit logs based upon their interpretation of field logs and laboratory data. To prevent errors or omissions, the logs included in a geotechnical engineering or geologic report should never be redrawn for inclusion in architectural or other design drawings. Only photographic or electronic reproduction is acceptable, but recognize that separating logs from the report can elevate risk. File No. 0186-673-00 Page C-2 LOP February22, 2006 GIVE CONTRACTORS A COMPLETE REPORT AND GUIDANCE Some owners and design professionals believe they can make contractors liable for unanticipated subsurface conditions by limiting what they provide for bid preparation. To help prevent costly problems, give contractors the complete geotechnical engineering or geologic report, but preface it with a clearly written Ietter of transmittal. In that letter, advise contractors that the report was not prepared for purposes of bid development and that the report's accuracy is limited; encourage them to confer with GeoEngineers and/or to conduct additional study to obtain the specific types of information they need or prefer. A pre -bid conference can also be valuable. Be sure contractors have sufficient time to perform additional study. Only then might an owner be in a position to give contractors the best information available, while requiring them to at least share the financial responsibilities stemming from unanticipated conditions. Further, a contingency for unanticipated conditions should be included in your project budget and schedule. CONTRACTORS ARE RESPONSIBLE FOR SITE SAFETY ON THEIR OWN CONSTRUCTION PROJECTS Our geotechnical recommendations are not intended to direct the contractor's procedures, methods, schedule or management of the work site. The contractor is solely responsible for job site safety and for managing construction operations to minimize risks to on -site personnel and to adjacent properties. READ THESE PROVISIONS CLOSELY Some clients, design professionals and contractors may not recognize that the geoscience practices (geotechnical engineering or geology) are far less exact than other engineering and natural science disciplines. This lack of understanding can create unrealistic expectations that could lead to disappointments, claims and disputes. GeoEngineers includes these explanatory "limitations" provisions in our reports to help reduce such risks. Please confer with GeoEngineers if you are unclear how these "Report Limitations and Guidelines for Use" apply to your project or site. GEOTECHNICAL, GEOLOGIC AND ENVIRONMENTAL REPORTS SHOULD NOT BE INTERCHANGED The equipment, techniques and personnel used to perform an environmental study differ significantly from those used to perform a geotechnical or geologic study and vice versa. For that reason, a geotechnical engineering or geologic report does not usually relate any environmental findings, conclusions or recommendations; e.g., about the likelihood of encountering underground storage tanks or regulated contaminants. Similarly, environmental reports are not used to address geotechnical or geologic concerns regarding a specific project. BIOLOGICAL POLLUTANTS GeoEngineers' Scope of Work specifically excludes the investigation, detection, prevention or assessment of the presence of Biological Pollutants. Accordingly, this report does not include any interpretations, recommendations, findings, or conclusions regarding the detecting, assessing, preventing or abating of Biological Pollutants and no conclusions or inferences should be drawn regarding Biological Pollutants, as they may relate to this project. The term `Biological Pollutants" includes, but is not limited to, molds, fungi, spores, bacteria, and viruses, and/or any of their byproducts. If Client desires these specialized services, thcy should be obtained from a consultant who offers services in this specialized field. FileX7. 0186-673-00 Page C-3 GEoENGINEERird February 22, 2006