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HomeMy WebLinkAboutLUA-07-074_Misc. ' ;"· i\ ';1 .;._ cr'11 ! .... \ r Cut and Fill for 1-405 Transmission Line Relocation Work in the City of Renton Uooer Thunder Area 1 Cut Lower Thunder Area 2 Cut f-' ----- Wetland 2.82 Area 3 Cut Total Cut Unner Thunder Area 1 Fill Lower Thunder Area 2 Fill Wetland 2.82 Area 3 Fill Total Fill Temporary Cut Temporary Fill - ----· ·--- 1300 yards -- 1150 vards 832 yards 568 yards 0 1200 100 100 850 200 GEoENGINEER~ GEOTECHNICAL ENGINEERING SERVICES TALBOT HILL ACCESS ROADS RENTON, WASHINGTON JULY 11, 2007 FOR PUGET SOUND ENERGY File,Vo. 0186-7/0-01 r Geotechnical Engineering Services Talbot Hill Access Roads Renton, Washington File No. 0186-710-01 Prepared for: Puget Sound Energy P.O. Box 90868, EST-04E Bellevue, Washington 98009-0868 Attention: David Wilcox, PE Prepared by: GeoEngineers, Inc. 8410154'" Avenue NE Redmond, Washington 98052 (425) 861-6000 Timothy D. Bailey \ Geotechnical Engineer Shaun D. Stauffer, PE Associate TB25DSja Redm:\00\Finals\O 18671001 Final R.doc Copyright© 2007 by GeoEngmeers, Inc. All rights reserved. July 11, 2007 EXPIRES 1/23/ off Disclairner: Any e:ectronic form. facsimile or hard copy of the ongina! document (em.::i1l, text, table, andlor figure). 1f provided, and any attachments are only a copy of the ongma! document. The original document is stored by Geo Engineers, Inc. and will serve as the otlicial document of record. File No. 0186-7/0-01 TABLE OF CONTENTS INTRODUCTION AND PROJECT UNDERSTANDING .... FIELD EXPLORATIONS AND LABORATORY TESTING SITE CONDITIONS. GEOLOGIC SETTING .......... . GEOLOGY SURFACE CONDITIONS ..... SUBSURFACE CONDITIONS SENSITIVE AREAS ........ . GEOLOGIC RECONNAISSANCE .... CONCLUSIONS AND RECOMMENDATIONS SENSITIVE AREAS IMPACTS .. EARTHWORK ........................ . Earthwork Considerations Clearing and Grubbing ..... Subgrade Preparation. Erosion and Sedimentation Control ...... . Structural Fill Materials ....... . Temporary Slopes Permanent Slopes .............. . Benching ................... . Road Section and Drainage ............................. . ADDITIONAL GEOTECHNICAL SERVICES LIMITATIONS REFERENCES List of Figures Figure 1. Project Location Plan Figure 2. Geology Map Figure 3. Sensitive Areas -Erosion and Steep Slope Figure 4. Geologic Hazard Areas -Seismic and Coal Mine APPENDICES Appendix A -Field Explorations Appendix A Figures Figure A-1 -Key to Exploration Logs Figures A-2 ... A-4 -Log of Borings Appendix B -Laboratory Testing Appendix B Figures Figure B-1 -Sieve Analysis Results Appendix C -Report Limitations And Guidelines For Use File No. 0/86-7/0-01 July 11. 100 7 Pagei Page No. . .... 1 .................. 1 .2 ..2 .......... 2 . ................ 3 .3 . ......... 4 . ........... 4 ........ 5 . .. 5 . ....... 6 ....... 6 ..6 . ................... 6 . ....... 6 ...7 ... 8 ...8 . ....... 9 . .. 9 ................... 9 .... 9 ...... 10 GrnENGINEERu::;i GEOTECHNICAL ENGINEERING SERVICES TALBOT HILL ACCESS ROADS RENTON, WASHINGTON FOR PUGET SOUND ENERGY INTRODUCTION AND PROJECT UNDERSTANDING This report presents the results of our geotechnical engineering sen-ices for the Talbot Hill Access Roads project near Renton, Washington. The site is shown relative to surrounding physical features on the Project Location Plan, Figure l. We understand that the existing Talbot Hill transmission lines in the vicinity of 1-405 will be reconfigured to allow for the expansion of I-405. Most of the existing transmission line structures in the vicinity of I-405 will be relocated as part of this project. In order to access these new transmission line structures, roads will be constructed to provide temporary construction and permanent maintenance access. We understand that the construction of the roads in the project corridor will involve minimal grading, and the roads will be surfaced with gravel. The purpose of this study is to evaluate geologic hazards within the project corridor and to provide geotechnical engineering conclusions and recommendations for the design and construction of the proposed access roads. We understand that Wetland Permitting Services is completing the wetland study for this project. Our geotechnical engineering services were completed in general accordance with our proposal dated May 24, 2007, and included the following primary tasks: • Reviewing previous geotechnical and geologic information for the site vicinity; • Completing geologic reconnaissance of the site to evaluate the presence of geologic hazards as defined by the City of Renton; • Providing geotechn1cal recommendations for construction of the access roads with regard to any sensitive areas or geologic hazards; and • Preparing this geotechnical engmeering report. FIELD EXPLORATIONS AND LABORATORY TESTING The subsurface soil and groundwater conditions along the planned access road alignments were evaluated by completing eight hand explorations (HA-I through HA-8) to depths of 1.2 to 4 feet below existing site grades and by reviewing existing subsurface information for collected for design of the new transmission line structures. The existing information included three borings (B-0/6A, B-0/7A and B-0/13) completed to depths of 29 to SOY, feet. The approximate locations of the bonngs and hand explorations are presented on the Geology Map, Figure 2. Details of the field exploration program and logs of the explorations are presented in Appendix A. Soil samples were obtained during drilling 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. A descript10n of the laboratory testing and the test results are presented in Appendix B. File No 0/86-7/0-01 July I I. :!007 P11ge 1 GEOENGINEER~ I SITE CONDITIONS GEOLOGIC SETTING The project corndor is located within the central Puget Lowland bordered by the Cascade '\fountains to the east and the Olympic Mountains to the west. The Puget Lowland is a north-south trending trough consistmg of Holocene penod deposits generally overlying a sequence of relatively unweathered glacial and mterglacial sediments deposited during the ice ages of the Quatemm)' period. This region has experienced at least six glaciations in the past 2 million years. In the central Puget Lowland, the most complete geologic record of the Quaternary period includes the most recent glaciation, the Vashon stade of the Fraser glaciat10n. The advance and retreat of the Vashon age Puget glacial lobe, approximately 18,000 to 13,000 years ago, deposited most of the near-surface materials and sculpted most of the present landforms withm the Puget Lowland. The deposits of this glacial episode reflect a wide range of glacial depositional environments. As the glacier advanced southward, streams deposited sediment that formed a broad plam in front of the advancing glacier. Gravel-size material was deposited close to the glacier, while silt and clay material was transported farther from the glacier. The advance deposits therefore grade from coarse to fine with increasing depth, with silts and clays (lake deposits) at the base, then coarse-gramed sand and gravel at the top. Lodgement till, consisting of a non-stratified, well-graded deposit of particle sizes ranging from clay to large boulders, was deposited directly from the glacier itself The most conspicuous aspect of glacial till is its consolidat10n, the result of being overridden by the glacial ice. The maximum ice thickness was approximately 3,000 feet in the project vicinity. As the glacier retreated, the depositional sequence was repeated in the reverse order of the glacial advance, with first coarse-grained gravel and sand, then fine-grained silts and clays. The retreat was rapid relative to the advance of the glacier, and the recessional deposits are generally not as thick as the advance deposits. After the Fraser glaciation, Holocene period sediments were deposited over the glacial soils. These deposits typically consist of alluvial soils in river valleys, beach and marine deposits along shorelines, and colluvial deposits (landslide materials) along slopes. Peat and other organic soils occur in numerous depressional areas at the surface. Some of these Holocene period sediments have been modified by human activity, including cut and fill operations. Bedrock outcrops are present in the project corridor, generally on Talbot Hill to the east ofl-405. GEOLOGY Published geologic information for the project vicinity includes United States Geological Survey (USGS) maps for the Renton quadrangle (Mullmeaux, 1965) and a State of Washington Department of Natural Resources (DNRJ map for King County, Washington (Livingston, 1971). The maps indicate that three geologic units are present within the project corridor. Listed generally youngest to oldest, these units are: • Modified land (m) consisting of land modified by widespread or discontinuous fill placement. Modified land is mapped west and north of the project corridor. • Glacial till (Qvt) consisting of a very dense, nonsorted mixture of clay, silt, sand, gravel, cobbles and boulders. The upper 2 to 5 feet ts often weathered and typically medium dense to dense. Glacial till is mapped within the eastern portion of the project corridor. • Renton formation (Tpr) (bedrock) consisting of fine-to medium-grained arkosic and feldspathic, micaceous sandstone, but including some siltstone, sandy shale, and beds of coal and carbonaceous shale. The bedrock is characterized by bedding and faulting, and the thicknesses range up to approximately 2,500 feet. Bedrock ts mapped at the ground surface throughout the majority of the proJect corndor. Bedrock is overlain by glacial till in the eastern portion of the project corridor, and by fill/modified land in the western portion of the project corridor. File /Vo. OJ 86-710-01 July 11. 2007 Pagel GEOENGINEER.g The geology, based on the DNR Geographic Information System (GIS) Layer and the above-referenced maps, is depicted on the Geology Map, Figure 2. SURFACE CONDITIONS The project corridor runs generally east-west down Talbot Hill and across 1-405 and Benson Road. The approximate alignment of the access roads is shown on Figures 2, 3 and 4. There are six Puget Sound Energy transmission lines that run through the project corridor: Talbot Hill-O'Brien #3, Talbot Hill-Boeing Renton, Talbot Hill-Metro Renton, Talbot Hill-O'Brien #2, Talbot Hill-Christopher and Talbot Hill-Asbury. On the west side of Benson Road, the lines turn to the west and south. 1-405 and Benson Road are roughly parallel within the project corridor, and cross the corridor in a north-south direction. The topography along the project corridor begins at the top of Talbot Hill near Grant Avenue South at about Elevation 340 feet, and slopes down to the west at about 20 percent. The topography is hummocky and uneven, possibly because of previous mining activities in the area. A steep ravine (side slope about 70 percent or greater) cuts across the project corridor ma north-south direction. The cut slopes on the east side of 1-405 are mclined at about 70 percent or flatter. On the west side of 1-405, the topography slopes down to Benson Road, and then west of Benson Road, the topography slopes down to the base of the hill at about 60 percent or flatter. There are some areas of overland flow in the upper areas of Talbot Hill, where runoff from the hill runs along the ground surface. The surface flow appears to be perched on the bedrock. A stream flows along the bottom of the steep ravine and through a culvert under 1-405, discharging on the west side of 1-405 near Benson Road. The stream is then conveyed in a concrete-line channel along the base of the hill west of Benson Road to the southwest. There is a large wetland area at the base of the hill between Benson Road and Talbot Road. Vegetation within the project corridor generally consists of thick blackberries, brush and small trees. Areas outside the project corridor are forested with coniferous and deciduous trees, with undergrowth typical of the Puget Sound region. There are wetland grasses and vegetation in the area of the wetland between Benson Road and Talbot Road. SUBSURFACE CONDITIONS Tlie primary soil units observed in the explorations include fill/loose soil and bedrock (Renton Formation sandstone). The table below summarizes our explorations. Exploration B-016A 8-017 A B-0113 HA-1 HA-2 HA-3 File No. 0/86-?!0-0! July I/, 1007 HA-4 HA-5 HA-6 HA-7 HA-8 Fill/Loose Soil (feet) 0-4.5 0-12 0-9 0-3.5 0-3.5 0-1.2 0-3.5 0-2.5 0-1.5 0-3 0-2.5 Bedrock (feet) Groundwater Depth (ft) 4.5-29 ""'"" ____ . ···-··-· 12-49 8 9-50.5 {water at ground surface) 3.5 3.5 (water at ground surface) 1.2 3.5 2.5 (water at ground surface) 1.5 3 2.5 Page] GeoENGINEER~ SENSITIVE AREAS Most of the project corridor lies in or adpccnt to land designated as sensitive areas or geologic hazard areas. Published sensitive area and geologic hazard areas for the project vicinity include eros10n potenttal, coal mine hazards, seismic hazards, landsltde hazards and steep slope hazards. Data regarding severe eros10n potential were obtained from the Natural Resources Conservation Service (:\~CS) soils database. The data for the geologic hazards was provided by the City of Renton and King County. The sensitive areas and geologic hazards in the project vicinity are shown in Figures 3 and 4, respectively. Figure 3 identifies several areas along the project corridor as having steep slopes (slopes greater than 40 percent). These areas are mainly along the south side of I-405 and along a steep ravine that runs in a north-south direction on the east of 1-405. These hazards are likely minor because the Renton Formation is located at shallow depths in these areas. If landsliding occurs, the type of landslide would most likely be very shallow surficial sliding of the soil overburden or highly weathered, decomposed sandstone. The Renton Formation (bedrock) has been mined for coal throughout the Renton area. The mined areas are shown as coal mine hazards in Figure 4. The eastern portion of the proiect corridor is located within mapped coal mine hazard areas. A rock tunnel to access the mined area crosses below 1-405 at approximately milepost (MP) 3.05, just north of the project corridor. According to historical records (Geo. Watkins Evans Consultmg, 1919), the entrance of the rock tunnel was located at Elevation 55.3 feet. The tunnel sloped towards the southeast to the first mme level area, located approximately 500 feet east ofl-405, at Elevation 58.7 feet. Daily records kept by Washington State Department of Transportat10n (WSDOT) personnel during construction of 1-405 note that the rock tunnel was "quite large and will take considerable concrete and material to block it" (WSDOT, September 26). Over the next five working days (WSDOT, September 27 to October 3), they "placed gravel and concreted inside face in the mine tunnel" and "completed placement of gravel at the mine tunnel entrance and placed concrete on the outside face and in the top to seal the tunnel entrance." It is thought that the tunnel diameter was on the order of25 feet. Since construction of 1-405, there has been no evidence of roadway subsidence in the vicinity of the rock tunnel. There has also been no evidence of subsidence in the area of the existing transmission line structures. Based on the available information and based on the depth to the tunnels, it appears that there is a low coal mine hazard risk in the project corridor. Figure 4 also indicates that the large mine tailings pile east of I-405, directly north of the proiect corridor, is mapped as a seismic hazard area because of the potential for liquefaction of the loose tailings. The areas of modified land west of the project corridor are also shown as seismic hazard areas due to the potential for liquefaction. The liquefaction hazard risk appears low for the project as these areas are outside of the project corridor. GEOLOGIC RECONNAISSANCE We completed a two-step geologic reconnaissance to identify geologic or other sensitive areas along the project corridor. The first step consisted of a desk-level study that involved reviewing the above geologic, sensitive areas and geologic hazard area maps and available subsurface information. In addition, we reviewed available "bald earth" Laser Imaging Detection and Ranging (LiDAR) images of the project corridor to aid in assessing geologic hazards. LiDAR consists of transmitting laser pulses from the air (such as from a helicopter) and then recording the reflected laser pulses as they return from the ground, vegetation, structures and other features. A "bald earth" image can be generated wnh the recorded data by plotting only those laser pulses that were reflected from the ground. Hence, a "bald earth" image shows the terrain (topography) with the vegetation, structures and other features stripped from the image and can be utilized to reveal previously hidden features such as landslides, faults and erosion hazards. File No. 0186-710-0! July I I. 2007 Pllge 4 GEOENGINEER~ The second step consisted of field study to define more accurately the geologic features. sensitive areas and hazard areas identified during the desk-level study. Additionally, sensitive and/or hazard areas observed during the field study that were not mapped or apparent during the desk-level study were idenufied and documented. The field geologic reconnaissance was completed by staff level personnel from our firn1. Based on the results of our geologic reconnaissance, it appears that the sensitive areas and geologic hazard areas along the project corridor have been fairly accurately portrayed in the published maps (as shown on Figures 2 through 4), with a few exceptions: • Glacial till was not encountered in the hand explorations in the eastern portion of the project corridor. Instead, bedrock was encountered at shallow depths below the surficial fill or loose weathered soils. • The steep slope areas west ofl-405 do not appear to line up with the topography in several areas. • The uphill ( eastern) access road crosses a shallow ravine that is mapped as a stream channel. Based on our reconnaissance, the water flow in this area is not a stream channel, but rather consists of surface or shallow subsurface flow over a large area. CONCLUSIONS AND RECOMMENDATIONS SENSITIVE AREAS IMPACTS As part of our investigation of the project corridor, we evaluated the impacts the access roads project would have on identified sensitive areas and geologic hazards. These erosion potential, coal mine hazards, seismic hazards, landslide hazards and steep slope hazards. The proposed access roads will be located within mapped erosion potential areas. We recommend that temporary erosion control and permanent revegetation be included with the project plans to mitigate this hazard. It is our opinion that with the use of best management practices for erosion, the proposed grading for the access roads will not cause adverse soil erosion at the project site. The eastern portion of the project corridor is located in a mapped coal mine hazard area. However, because of the small amounts of grading ( cuts of generally less than 4 feet) and the depth to the mine workmgs (upwards of 100 feet in this area), it is our opinion that there is a low risk of the grading activities uncovering coal mine tunnels. The mapped seismic hazards in the project area are associated with the large tailings pile east of 1-405 (north of the project corridor) and the modified land west of the base of Talbot Hill (west of the project corridor). The proposed access roads will involve minimal amounts of grading. Additionally, the grading will generally not occur in these areas and will not increase the risk of soil movement due to liquefacnon; therefore, 1! is our opinion that there is a low seismic hazard risk for this project. There are large areas within the project corridor that are mapped as landslide or steep slope hazards. However, the alignment of the access roads does not encroach within these areas. If landsliding does occur, the type of landslide would most likely be very shallow surficial sliding of the soil overburden or highly weathered, decomposed sandstone and would not impact the constructed roadways. Provided the roadways are constructed as recommended below, it is our opinion that there is a low landslide and steep slope hazard risk for this project. Filelv'o 0/86-710-01 July 1 I. 200? Page 5 GEOENGINEER~ EARTHWORK Earthwork Considerations We anticipate that on-site soils and bedrock can be excavated with conventional excaval!on equipment, such as trackhoes or dozers. R1ppmg may be required to excavate the bedrock. Blasting should not be allowed because of the surrounding urban environment. Clearing and Grubbing The existing ground surface along the proposed access road alignments is typically vegetated with thick blackberries, brush and trees as described in the "Surface Conditions" section of this report. The area along the proposed road alignments should be cleared and grubbed in accordance with Section 2-01 of the 2006 WSDOT Standard Specifications. We estimate that clearing and grubbing will be limited to the upper 6 inches of the topsoil and root zone. Subgrade Preparation The exposed subgrade should be evaluated after site grading complete and prior to placement of structural fill. Proof-rolling with heavy, rubber-tired construction eqmpment should be used for this purpose during dry weather and if access for this equipment is practical. Probing should be used to evaluate the subgrade during periods of wet weather or if access is not feasible for construction equipment. Soft areas noted during proof-rolling or probing should be excavated and replaced with compacted structural fill. 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. Implementing an erosion and sedimentation control plan will reduce the project impact on erosion-prone areas. The plan should be designed in accordance with applicable city, county and/or state standards. The plan should incorporate basic planning principles, including: • Scheduling grading and construction to reduce soil exposure; • Revegetating or mulchrng denuded areas; • Directing runoff away from denuded areas; • Reducing the length and steepness of slopes with exposed soils; • Decreasing runoff velocities; • Preparing drainage ways and outlets to handle concentrated or increased runoff; • Confining sediment to the project site; and • Inspecting and maintaining control measures frequently. In addition, we recommend that sloped surfaces in exposed or disturbed soil be restored so that surface runoff does not become channeled. 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 erosion and reduce transport of sediment to adjacent areas and receiving waters. Permanent erosion protection should be provided by paving or landscape plantmg. 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 to 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. Fife No. 0186-7,'0-0J July I I. 2007 Page 6 GeoENGINEER~ Structural Fill Materials General. Material used to construct or surface the proposed access roads is classified as structural fill for the purpose of this report. Structural fill material quality varies depending upon its use as described below. • At a minimum. structural fill should meet the criteria for common borrow as descnbed in Section 9-03.14(3) of the 2006 WSDOT Standard Specifications. The on-site soils and bedrock generally meet the critena for common borrow. • Structural fill placed as crushed surfacing base course for roadway surfacing should conform to Section 9-03.9(3) of the 2006 WSDOT Standard Specifications, summarized in the followmg table. Sieve Size Percent Passing 1% inch 100 ..... 1 inch 80-100 % inch 50-80 U.S. No. 4 25-45 U.S. No. 40 3-18 U.S. No. 200 7.5 Max • Quarry spalls placed below the road to provide drainage in wet areas should be 2-to 4-inch quarry spalls. Fill Placement and Compaction Criteria. Structural fill should be placed in loose lifts not exceeding 6 inches in thickness. Each lift should be conditioned to the proper moisture content and compacted before placing subsequent lifts. Structural fill supporting the access roads should be compacted to at least 90 percent of the maximum dry density (MOD) in general accordance with the American Society for Testing and Materials (ASTM) D 1557 test procedure. Structural fill placed within I foot of the finished road subgrade elevation should be compacted to at least 95 percent of the MDD. We recommend that GeoEngmeers be present during placement of structural fill. Geo Engineers will perform in-place moisture-density tests in the fill to evaluate whether the work is being done in accordance with the compaction specifications, and to advise on any modifications to procedures that may be appropriate for the prevailing conditions. Weather Considerations. When the moisture content of the on-site soils is more than a few percent above the optimum moisture content, these s01ls become relatively soft and unstable, operation of equipment on these sods will be difficult, and it will be difficult to meet the required compaction criteria. Additionally, disturbance of near-surface soils should be expected if earthwork is completed during periods of wet weather. It will be preferable to schedule site preparation and earthwork activities during extended periods of dry weather when the soils will: (I) be less susceptible to disturbance; (2) provide better support for construction equipment; and (3) be more likely to meet the required compaction criteria. The wet weather season in western Washington generally begins in about October and continues through May; however, periods of wet weather may occur during any month of the year. The optimum earthwork period for the soils expected at the site is typically June through September. If wet weather earthwork is unavoidable, we recommend that: • The ground surface in and around the work area should be sloped so that surface water is directed away from the work area; File No. 0186-7/0-0/ July 11. 2007 Page 7 GEOENGINEER~ ! ! • The ground surface should be graded such that areas of ponded water do not develop. • The contractor should take measures to prevent surface water from collecting m excavations and trenches. '.1easures should be implemented to remove surface water from the work area. • Erosion control techniques should be implemented to prevent sediment from leaving the site, with special attent10n to seepage and surface water flow in areas of Talbot Hill. • Earthwork activities should not take place during periods of heavy precipitation. • Slopes with exposed soils should be covered with plastic sheeting. • The contractor should take necessary measures to prevent on-site soils and soils to be used as fill from becoming wet or unstable. These measures may include the use of plastic sheeting to cover work areas and stockpiles. The site soils should not be left uncompacted and exposed to moisture. Sealing the surficial soils by rolling with a smooth-drum roller prior to periods of precipitation will help reduce the extent that these soils become wet or unstable. • Construction activities should be scheduled so that the length of time that soils are left exposed to moisture is reduced to the extent practicable. Temporary Slopes We recommend that temporary unsupported cut slopes greater than 4 feet deep be inclined no steeper than 1 Y,I-1: 1 V (horizontal to vertical). This recommendation applies to fully dewatered conditions. Flatter slopes may be necessary if seepage is present on the cut face. Temporary cut slopes should encroach no closer than 5 feet laterally from steep slopes, structures, or other improvements on the site. Some sloughmg and raveling of the cut slopes should be expected. Temporary covering, such as heavy plastic sheeting, should be used to protect these slopes during penods of rainfall. Surface water runoff from above cut slopes must be prevented from flowing over the slope face by using berms, drainage ditches, swales or other appropriate methods. If temporary cut slopes experience excessive sloughing or raveling during construction, it may become necessary to modify the cut slopes to maintain safe working condittons and protect adjacent facilities or structures. Slopes experiencing excessive sloughing or raveling can be flattened or can be regraded to add intermediate slope benches, or additional dewatering can be provided if the poor slope performance is related to groundwater seepage. 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. We recommend that the finished slope faces be compacted by track-walking with the equipment running perpendicular to the slope contours so that the track grouser marks help provide an erosion-resistant slope texture. Permanent fill slopes should be constructed no closer than IO feet from the top of adjacent slopes or a lateral distance equal to the vertical height of the permanent fill slope, whichever is greater. To reduce erosion, newly constructed slopes should be 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 or straw/coconut matting should be used to protect the slopes during periods of rainfall. File No. OJS6-7JO-OI July I I. :!007 PageS GEOENGINEER~ Benching In the area where fill will be placed against existing slopes. the fill should be effectively keyed mto the existing slope as described tn Section 2-03 .3( 14) of the 2006 WSDOT Standard Specifications. Road Section and Drainage We recommend that the road section consist of a minimum of 12 inches of crushed surfacing base course overlying compacted structural fill or native soil. This roadway section is intended for permanent mamtenance access. In some areas of the project corridor on Talbot Hill, surface or shallow subsurface water runoff will cross the proposed access road alignment. In these areas, at least 2 feet of quarry spalls should be placed below the road to provide a path for the runoff The quarry spalls should extend a minimum of 2 feet beyond the edges of the road to ensure that the spalls do not become inundated with fine material. ADDITIONAL GEOTECHNICAL SERVICES We recommend that GeoEngineers be retained to provide geotechnical design assistance as the project evolves and during construction to confirm that subsurface conditions are as assumed for design. At a minimum, we recommend the following additional services: • GeoEngineers should be retained to review the project plans and specifications when complete to confirm that our design recommendations have been implemented as intended. • During construction, GeoEngineers should observe the road construction, particularly in the upper areas of Talbot Hill where there is surface or shallow subsurface water flow. The purposes of GeoEngineers' construction phase services are to confirm that the subsurface conditions are consistent with those observed in the explorations and other reasons described in Appendix C, Report Limitations and Guidelines for Use. LIMITATIONS We have prepared this report for the exclusive use of Puget Sound Energy for the Talbot Hill Access Roads project in Renton, Washington. The data should be provided to prospective contractors for their bidding or estimating purposes, but our report and interpretations should not be construed as a warranty of the subsurface conditions. 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 titled "Report Limitations and Guidelines for Use" for additional information pertaining to use of this report. File No. 0186-7!0-0J Jilly I l, ]007 Page 9 GrnENGINEER~ REFERENCES Geo. Watkins Evans Consultmg Mining Engineer, 1919, "Geologic Structure \!lap of Renton Coal Mine, Renton Coal Company, Renton, Washington," March 13, 1919. Livingston, Jr., V.L 1971, State of Washington Department of Natural Resources. D1v1s10n of Mines and Geology, "Geology and Mineral Resources ofKmg County, Washington." Bulletin No. 63. Mullineaux, D.R., 1965, United States Geologic Survey, "Geologic Map of the Renton Quadrangle, King County, Washington," Geologic Quadrangle Map GQ-405. Washington State Department of Transportation, September 20-0ctober 7, WSDOT personnel daily field records (Mr. Jolley) regarding original 1-405 construction. Washington State Department of Transportation, 2006, "Standard Specifications for Road, Bridge and Municipal Construction." File.Vo. 0/86-710-01 July I I. 1007 Page IO GEOENGINEERs,0 r-. 0 0 N a, ., C: ::, -, "O ., "' ·s: ., er 9 0 .t;; ~ 0 UJ er Data Sources: DOQQ from Washing ton State Department of Ecology ----1,00 0 0 Th is map is for information purposes . Data were comp il ed from multiple sources as listed on th is map. T he data sources do no t guarantee these data are accurate or comp lete. There may have been updates to the data since th e pub lication of th is map. The master fi le is stored by GeoEngineers, Inc. and wi ll serve as the official record of this comm unication . The loca ti ons of all fea tu res sh own are approximate. 2,0 0 0 -Fe et oo.z trl Project Location Plan Puget Sound Energy Ta lbot Hill T ransm iss ion Line Rel oca t ion GEoENGINEERS C} Figu re 1 ..... 0 0 N ai QJ C ::, -, ;;; ~ ·5 QJ 0:: a. "' ::E N QJ =i C'l u: 0:: vi 0 >< ~ Cl) g ~ ~ i!i~li If) .... ~~~ 13-o Q~ . ~~J -<-.-<'o / • • • • m Qvt I 5 ••• • • • • • I f- 0) o-<.. '\I'-":~·-' / • CEDAR I f-,..._ ~1 I ~ .............. "-., '·, '----, SMITH~r BURNETT -----~~LIAMS ::a Q ~o 'J.- MAIN ' ' -------------- :r to RENTON Qv i _ , I GRANT I 0~ / .~-------------~--------A( -.-: , a v i /~ : Base data fro m ESRI web service . Geology from Washingto n St ate Department of Nat ural Resources. River s from Washing ton State Department o f Ecology. .~ a: Thi s map is for in fo rma ti on purposes . Data we re com piled from multiple sources as listed on th is map . Th e data sou rces do not gua ran tee th ese data are rJ) Z accu rate or co mpl ete . Th ere may have bee n updates to the data sin ce t he publica tio n of thi s map. The m aster fil e is stored by Geo Engi neers, Inc. and will Legend • Proposed Pole Location -Proposed Access Road Al ig nment Et) Exp lorat ion Inters tates ---Highways Major Streets ===>• Ra ilroads ---Streets Surface Geology Unit, Description m , Modified Land (Holocene) Qvrl , Rec essiona l Outwash , Lowland Lacu s trian (Plei stoce ne ) Qvr. Recessional Outwash, Fraser-age (Ple istocene) Qvi , Recessional Outwash , Fraser-age (Pleistocene ) Qvt , G lac ial nu , F rase r-age (Pleistocene) -Tpr, Renton Fo rmation (E ocene ) Geology Map Pu get Sound Energy Ta lbot Hi ll Trans mi ssion Lin e Re location Figure 2 fil serve as the official reco rd of thi s comm uni ca tion. Th e locatio ns of all featu res s hown are approximate. tTl o::L_ ________________________________________________________________________________________________________ ~ GEoENGINEER~ ,-. 0 ~ ~ N OJ C: :, --, -i::i 3l ·s: OJ Cl'.'. "O )( E ~ Data Sources: ii Base data from ESRI web service. ,5 River data from Washington Department of Natural Resources. If. Erosion data from NRCS soils database. Cl w Cl'.'. Th is map is for informati on purposes. Data were com piled from multiple sources as listed on t his map. Th e data sources do not guarantee these data are accurate o r complete. There may have been updates to the data since the pub lication of this map. The master fi le is stored by GeoEngineers, Inc. and wil l serve as the official reco rd of this co mmunication. The locations of all fea tu res shown are approximate. ~{f}z trJ Legend • Proposed Pole Loca ti o n Severe Erosion Pote ntia l (NRCS) ->40 Percent S lopes Proposed Access Road Al ignment c::=::::, Interstates --· Highways Major Streets River 0 500 ---- Sensi t ive Areas Eros ion and Steep Slopes Puget Sound E nergy 1,000 -Feet Ta lbot Hi ll Transm iss ion Line Re location GEoENGINEER ~ Figure 3 ,._ 0 0 "' .... Cl) J: .... "' Cl) (t' I ; 1-? I C/J I Cl) w ~ J: .... ~ eEt1sOt1RO s "'b -~ a, C ::, -, -0 a, VJ ·;; a, 0::: -0 )( E .,: @ ::, C1) u: 0::: .; Cl X :E iii S? ~ ,._ cs:, a, 9 9 ti: .c iii a. Cl w 0::: Data Sources : Base data from ESRI web service. Rivers from Was hington Department of Natural Resources . Coal m ines , and Seismic from City of Renton and King County GIS . This map is for information purposes. Data we re compiled from multiple sources as listed on this map . The data sources do not guarantee these data are accurate or comp lete. Th ere may ha ve been updates to the data since the publication of this map. The master file is stored by GeoEngineers, Inc. and will serve as the official re cord of this communication . The locations of all features shown are approximate. .:==:=: • ,~;::....-_ . .... "' ~ ~-;--co "'I MILL AVES ~=_;:__ =------ ~-z m 0 • Prop osed P ole Location Proposed Access Road Alignment c:::::::::::::::, Interstates Highways Major Streets === Streets Railroads River Geologic Hazards al Coal Mine WH.U~ s. . H dA ~ e1sm1c azar rea 500 ---- Geologic Hazard Areas Seismic and Coal Mine Puget Sound Energy Talbot Hill Transmission Line Relocation GEoENGINEER~ Figure 4 1,000 -Fee GEoENGINEER~ APPENDIX A FJELD EXPLORA TJONS GENERAL APPENDIX A FIELD EXPLORATIONS Subsurface conditions were explored at the site by drilling three borings and completing eight hand explorations. The borings were completed to depths rangmg from 29 to SOY, feet below the existing ground surface. The drilling was performed by Holocene Drilling between January 22 and 24, 2007. The hand explorations were performed by a geologist from our firm on May 30 and 31, 2007. The exploration locations are shown on the Geology Map, Figure 2. BORINGS Borings B-0/6A, B-0/7 A and B-0/13 were completed using track-mounted, continuous-flight, hollow-stem auger drilling equipment. The borings were continuously monitored 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 exploration. The soils encountered in the borings were sampled at 2Y,-or 5-foot vertical intervals with a 2-inch outside diameter split-barrel standard penetration test (SPT) sampler. The samples were obtained by driving the sampler 18 inches into the soil with a 140-pound hammer free-falling 30 inches. The number of blows required for each 6 inches of penetration was recorded. The blow count ("N-value") of the soil was calculated as the number of blows required for the final 12 inches of penetration. This resistance, or N-value, provides a measure of the relative density of granular soils and the relative consistency of cohesive soils. Where very dense soil conditions or large particles precluded driving the full 18 inches, the penetration resistance for the partial penetration was entered on the logs. The blow counts are shown on the boring logs at the respective sample depths. Soils encountered in the borings were visually classified m general accordance with the classification system described in Figure A-1. A key to the boring log symbols is also presented in Figure A-1. The logs of the borings are presented in Figures A-2 to A-4. The bormg logs are based on our interpretation of the field and laboratory data and indicate the various types of soils and groundwater conditions encountered. The logs also indicate the depths at which these soils or their characteristics change, although the change may actually be gradual. If the change occurred between samples, it was interpreted. The densities noted on the boring logs are based on the blow count data obtained in the bonngs and judgment based on the conditions encountered. Observations of groundwater conditions were made during drilling and are presented on the boring logs. Groundwater conditions observed during drilling represent a short-term condition and may or may not be representative of the long-term groundwater conditions at the site. Groundwater condit10ns observed during drilling should be considered approximate. HAND 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 usmg a series of 3-foot rods. The auger was advanced into the soil by hand. The hand explorations were completed by a geologist from our firm who examined and classified the soils encountered, obtamed representative soil samples, observed groundwater conditions and prepared a summary log of each hand exploration. The subsurface conditions encountered in the hand explorations are presented in the "Subsurface Conditions" section of this report. File No. 0/86-7/0-01 July 11, 2007 Page A-1 GeoENGINEER~ 1 SOIL CLASSIFICATION CHART MAJOR DIVISIONS SYMBOLS TYPICAL 'GRAPH LETTER DESCRIPTIONS I u, WEc.-GRADC GRME~S GRAV:':L - CLEAN o['J°~ GW SJ.NC MIXTU":ES GRAV:C.L GRAVELS 1 ' AND 0 0 GRAVELLY (L -;-'LEa QA NC Fl~ESJ 0 0 0 ~ooRLY-GRAJE:) GRAV:C.S SOILS 0 0 GP GRAV:C. -SANC, MIXTURES ' COARSE , " ·,) SUY GRAVELS. GRAVEL SAND· GRAVELS WTH '< ' GM GRAINED MORET-AN 50% FINES -SI~ T MIXTURES QC C:JARSE SOILS F'l.ACTIO~ RETA11-EU 0~ NO (APPRECIABLE AMO~'Nl ~ CLAYEY GRAVELS. GRAVE.L SANC 4 SIEVE OF i'INCS) GC CU,Y MIXTURES : ~ SW WEL.-GRADEO SANOS, GRAVELLY CLEAN SANDS •: SANclS MORE THAN 50% SANO ... RETAINED ON NO AND (LITILE OR NO FINES) ! wa SIEVE SANDY SP ?OORLY-GRADED SANOS GRAVELLY SANJ SOILS MORE THAN 50% SANDS VVlTH SM Sil TY SANOS, SANO -s;L T OF COARSE FINES MIXTURES FRACTION PASSING NO 4 w SIEVE (APPRECIABLE AMC(INT SC CLAYEY SANOS. SAhlO • CLAY OF "INESI MIXT'jRES I INORGANIC SIL TS ROCK FLOUR ML CLAYEY SIL TS WITH SLIGHT I ?LASTICITY SILTS 0 '/ INORGANIC CLAYS OF LOW TO LIQUID LIMIT CL MEDIUM PLASTICITY, GRAVE'-L Y FINE AND / CLAYS. SANJY Ci..AYS, SIL Ti CLAYS LESS THAN 50 _EJl,N CLAYS GRAINED CLAYS SOILS . ' OL ORGANIC SILTS AND ORGAN1C SILTY Ci..AYS OF LOW PLASTICITY i.lORE f>;AN SO% I I I Ii MH INORGANIC SIL TS MICACEOwS OR PASSING NO 200 I I QIATOMACEOUS SIL TY SOILS SIEVE , SILTS LIQUID LIMIT 0 INORGANIC CLA~S OF H1GH AND G>sEATER THAN 50 CH PLASTICITY CLAYS I ORGANIC CLAYS ANO SIL TS OF OH MEDIUM TO HIGH PlASTICITY .<. ' ~~ ... HIGHLY ORGIINIC SOILS PT PEAT. HUMUS. SWAMP SOILS WITH =,.,. -HIGH ORGAN:C CON""E'ITS NOTE Multiple symbols are used to 1nd1cate borderlme or dual soil class1ficat1ons Sampler Symbol Descriptions II 2.4-inch I.D. split barrel [I Standard Penetration Test (SPT) [] Shelby tube ~ Piston I] Direct-Push ~ Bulk or grab Blowcount 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 GRAPH LETTER TYPICAL DESCRIPTIONS =-- --sa;-. %F AL CA CP cs DS HA MC MD oc PM PP SA TX UC vs NS 55 MS HS NT cc AC CR TS Cement Concrete Asphalt Concrete Crushed Rock/ Quarry Spalls Topsoil/ Forest Duff/Sod Measured groundwater level in exploration, well, or piezometer Groundwater observed at time of exploration Perched water observed at time of exploration Measured free product in well or piezometer Stratigraphic 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 soil unit Laboratory I Field Tests Percent fines Atterberg limits Chemical analysis Laboratory compaction test Consolidation test Direct shear Hydrometer analysis Moisture content Moisture content and dry density Organic content Permeability or hydraulic conductivity Pocket penetrometer Sieve analysis Triaxial compression Unconfined compression Vane shear Sheen Classification No Visible Sheen Slight Sheen Moderate Sheen Heavy Sheen 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 cond1t1ons Descriptions on the logs apply only at the specific exploration locations and at the lime the explorations were made; they are not warranted to be representative of subsurface conditions at other locations or limes. KEY TO EXPLORATION LOGS GEOENGINEER~ FIGURE A-1 Date!~) 01/22/07 Logged TB2 I Checked TB2 Drilled By ' By .. Drilling Holocene Jnlling Hollow-stem Auger Sarnplrrig SPT Contracior Method /vle'.hods --.------ Auger Hammer 140 lb hammer/30 in drop ' Drilling CME 850 Data 4-114-inch ID Data automatic Equipment . ------ Total 29 Suriace Groundwater Not Encountered Deoth (ft) Elevation (ft) Level (ft. bgs) ·-·--~· 1301698.11 VeGical Datum/ Easting(x) Datum System NAO 83 North1ng(y)· 174953.53 SAMPLES c " \ " = ~ ,; OTHER TESTS J'! ,ca 0 V E > MATERIAL DESCRIPTION ;f. £ ~ a. 0 w AND NOTES .c ID 0 E z -' " ec ·E-: 0. ro > " rn V :c 0. 0 .'J ID :, -§, c a ~ if/ a. 2 ~ .0 w ~ 0. ~-" E a E -C i::"' ·;u 0 2 0 D "' "' 0, oo C w ai 0 rn s " a " >, 20 os QC "' "' (!) -' (!) (f) 0 ::::::::::: TS 12 inches topsoil and roots •._:,: . .:.,:.· SM Brown silty fine to medium sand (very loose, wet) C . ] 12 I I C C ;.. 5- 118 82/11" ' /. SM ~ Brown silty fine to medium sand with gravel (very 10 Till-like fabric . dense, moist) (weathere<l sandstone) SA;%F=31 . .,..,.. SM Gray silty fine sand {very dense, moist) (sandstone) - - 10-I 3 -- 8 5013" . . . . . - - 15-I 4 --4 5014" . Drill l ft/min -- -- -- - 20-I 4 50/4" 5 ~~ SM Light brown silty fine sand (very dense, moist) 9 %f="29 -(sandstone) . Drill I ft/3 mm -. -. - . 25-15 5015" 6 ~ - ~ Drill I ft/10 min ~ --- ~ ~ ---a " ' . ---I i 50,/3" I • > w " 30-~ " 0 0 0 ~ . w 00 ~ ~ -~ z ~ 35- 6 ;\/ote: See Figure A-1 for explanation of symbols. ~ ~ w 00 ~ LOG OF BORING B-0/6A ~ " z Project: PSE Talbot Transmission Towers ~ GEOENGINEER~ 0 Renton, Washington 00 Project Location: ~ Figure A-2 " w Project Number: 0186-710-00 Sheet 1 of 1 > I Date(si 01123107 Log[c)CrJ TB2 · Ct1ccked TB2 Drilled By 3y - Drilling Holocene Drilling Hollow-stem Auger Sampling SPT Contrac'.or Method Metrods -------·----~---- Auger Hammer 140 lb hammer/30 in drop ' Drillirg CME 850 Oat;~ 4-114-inch ID Data automatic ' Equipment - Total 49 Surface Groundw2ter 8 Depth (t) Elevc1t1on (ft) Level (ft. :Jgs} ~-------------···-·-~------ Vertical Datum/ Easting(:<) 1301001.6 Datum System NAO 83 Northing(y) 175191.7 SAMPLES C w "' ill " n o3 ~ OTHER TESTS 2 'O 0 " E > MATERIAL DESCRIPTION "' ,Q ~ ci 0 ID ~c AND NOTES .c ID ~ E z _, u 0.0 ·c ...... -0. " > " " 2 ic ,e ID :::, Tu ID ~ 0 ~ "I 0-0. ~ .0 ~- 0 2 u ~ E ro ro "' o E ·-C c·© ID " ro ~ 0 ~> 0 0 C 0: ai U) U) s CJ_, CJ (/) :eu os 0 ft? TS 2 feet topsoil and roots f- :~:;;::-: ] ' SM Light brown with oxidation staining silty fine to medium 18 19 f-sand with a trace of organic matter (medium dense, - f-moist) (filJ?) - 5-] 18 18 z --SA;%F=27 " - " - --!. .· " ] 18 4 3 -e 10--- e . --SM Gray silty fine to medium sand (very dense, wet) f-(sandstone) I 9 50/3" 4 " . 15---Drill 1 fi/min . " . -e . e I 5 5015" 5 . 12 %0RG=4 . Drill I ft/min . _ With a trace of coal 20-- - . I . I 6 5016" 6 Drill I .ft/min -Black coal (very dense, moist) 25--- - - -- ] 5 50/5" 7 Drill l fr/3 min ---SM Gray silty fine sand (very dense, moist) (sandstone) 30-' -- ~ w " - i - 8 ' 35-] S 50!5" ' 10 Drill l ~'2 mm I %f-:o=47 -- Note: See Figure A I for explanation of symbols. LOG OF BORING B-0/7 A GEOENGINEER~ Project: PSE Talbot Transmission Towers Project Location: Renton, Washington Figure A-3 Project Number: 0186-710-00 Sheet 1 of 2 SAMPLES 2-"' "' 0 D ill OTHER TESTS .E' "O 0 • E > MATERIAL DESCRIPTION a'-.Q w 2" i © AND NOTES ~ :;; ,g ---" u ~c C. " > a " i 0. 0 .2 © = :2 ~ 0 w U/ g :;; 0 .0 ::, 0, © ~ ~-u ;; ro "' o E ·-C >, ·m C ~ • .Q D 0 O ~ 0 s C Q C ~ ::eu os 0: a, 1/) CJ---" CJ lfJ 35 ! ' . I i ' I ] 5013" 9 -Dnll l '.-, ftimin 40--- ' I J 5013" 10 Drill I ft/J min ' ' 45--- ' . - ' - ' ' -.. ] 50/3" 11 ' . 50-J . - - ' -I 55- - - - 60- - 65- - - 70- - 75- m --- ~ ~ -~ 5 6 ~ ~ ~ 6 LOG OF BORING B-0/7A (continued) ~ ~ z Project: PSE Talbot Transmission Towers GEoENGINEER~ Project Location: Renton, Washington Figure A-3 Project Number: 0186-710-00 Sheet 2 of 2 b " ~ 0 0 0 0 -' m • 9 a ;; " 6 ~ • • 0 " " " z ii' • > Date(s) ; Logged I Chccf",ed 01 /22/07 I TB2 Onlled I By I By ~ I Drilling Holocene Drilling Hollow-stem Auger Sarnpl1ng Contrac:or Method Methods Avger 4-1/4-inch ID I Hammer 140 lb hammer/30 in drop Orillinq Data Data automatic Equ1pffien1 ----- I Total 50.5 Surface I Groundwater Depth (fl_l Elevation (ft) Level (ft. bgs) Vertical I Datum/ I Easting(x): Datum System NAO 83 I Northing(y): SAMPLES :§. w '.le w .0 " ;;; 2 D 0 • E > MATERIAL DESCRIPTION o". "' ~ a. 0 "' ,g z .,_ ~ ro ID E _, u 0. 0 'C ·c --0. > ~ rn .,:_ 2 £ 2"' :0 To • ~ 0 ~ "I 0. 0 .0 ~-0 2 u .0 E ro ro o, o E --C ~·a:; ID 0 0 rn ' 0 ' >-0 O C a'. 00 "' U) s ('.) _, ('.) (/) ::, (.) OS 0 iy •.•.•.•.•.• TS Brown topsoil with grass and organic matter ::J:;;::: . SM Brown with oxidarion sta1mng silty fine to medium sand . ' (loose, wet) (weathered sandstone) . 118 5 I i . i . . I --5-118 5 ' ' . . ' ' . . ' ' ~~ ------------------------SM Reddish brown silty fine sand (medium dense to very 10-I 18 J ' -dense, wet) (weathered sandstone) -26 23 ' . ' . . ' . . -. . -. . ' 4 --15-112 50/4" ' . . . . . . . . . 20-I 6 50/1" 5 f-r-SM Gray silty fine to medlum sand (very dense, moist) . -(sandstone) . ·. . -. -. . . 25-] 2 5012" 6 -- . . -. - 30-] 4 50/4" 7 --11 . . . . I . . -. 35--- Note: See Figure A-1 for explanation of symbols. LOG OF BORING 8-0/13 Project: PSE Talbot Transmission Towers GEoENGINEER~ Project Location: Renton, Washington Project Number: 0186-710-00 TB2 SPT CME 850 1 1300566 174542 OTHER TESTS AND NOTES SA; %F= 32 Drill I ft/min %F= 32 Figure A-4 Sheet 1 of 2 SAMPLES C " ~~ ;; = D "i5 m OTHER TESTS 2 D 0 w E > MATERIAL DESCRIPTION "' !e ru 0.. :::; u AND NOTES © £ E z ~ u 0. 0 ~c ·c -;::::-0. 0 > "' 0 0 a; :c 3 ru 0 ~ 0 ~ <f; 0. 0. ~D Cl)+-' ::JCT, 0 2 u 0 l, C ;;; ro o, o E 0 § 2:-© © " a ~ 0 ~ ~ C 0: ijj <f; <f; :;: (9~ (;) (J) 2:u:oS 35 ]' )IJ-;,:r " ' ! Drill] fvmin - L - -' ·. C 40 · ] 4 50/..J." ,, ~ -Drill 1 ft/min -L - -L - - -' . 45-l 5 50/5" IU '--Drill I ft/min C - C - -- -- e-0 -. 5 50/5" II ~ - -J Drill l fl/min - - - 55- - - 60- - - - - 65- - - - 70- - - - - 75- - . LOG OF BORING B-0/13 (continued) GEOENGINEER~ Project: PSE Talbot Transmission Towers Project Location: Renton, Washington Figure A-4 Project Number: 0186-710-00 Sheet 2 of 2 GEoENGINEER~ APPENDIXB LABORATORY TESTING I APPENDIX B LABORATORY TESTING GENERAL Soil samples obtained from the explorations were transported to our laboratory and examined to confirm or modify field class1ficat1ons, as well as to evaluate index properties of the soil samples. Representative samples were selected for laboratory testing consisting of moisture content determinations, percent fines and grain size distribution. The tests were performed in general accordance with test methods of the American Society for Testing and Materials (ASTM) or other applicable procedures. 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 U.S. No. 200 mesh sieve to determine the relative percentages of coarse-and fine-grained particles in the soil. The percent passmg 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 D 422 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. FileiVo. 0/86-7/0-01 Jtdy JI. 2007 Page B-1 GeoENGINEERs_O 0186-710-00 TB2: CTS: cts 2-12-07 (Sieve.pp!) G) m 0 m z C\ -z m m :::0 ~ "Tl 15 C ;,:i m rp ... !!! m < m )> z )> ~ Cf) ui ;,:i m Cf) C ~ I- I C) w s >-Cll C) z (/) (/) <l'. CL I-z w u 0::: w CL U.S. STANDARD SIEVE SIZE 1" IS' 3/4" 3/8"" 114 #10 #20 #40 #60 #100 f/200 • I • 1----. f ' --. ---j-, - -Jtmltfl -- I I 11 I i _] __ -· ; I I-HMEtJl+ij~8=11 _:wq_r1J N. ] __ ·":I 1 70 .... ,_,_ 60 1~1-1·~-·-- H !~m=-1 ]: f---1---- --I---I----I I ·1j+-i-+-l-----t--·-·I ,++---+-- ---1---------+ ---1- + ;1-i-1-1-,- ---_-J -L---= I _ I ... -' I T-- ~Jtff+_j___J t1 -I _ I __ I 50 ~, , _j_,~-1----1 1 : , 1- I -J ! - I --- 40 ++--· + 30 ~--•-·-. t I' I I --j-f I ··.I --11 Ii ! ·I 20 -+---1 -; -~ : -+ : : '--+---+--11~~H~f Jrlll L 1 +-+--'---+---4-W T . -/-J-: ·--. I I I ] ---1r-----I ·•--·--· 0 i __ J i 1±_--L, .. 1 tu· :-_-:..: ·_ 1000 I SYMBOL • D 0 100 COBBLES EXPLORATION NUMBER 8-0/BA 8-0/?A B-0113 10 GRAVEL COARSE l FINE DEPTH /ft\ 5 5 10 1 0.1 0.01 GRAIN SIZE IN MILLIMETERS I SAND SlLTORCLAY I COARSE]' MEDIUM FINE SOIL CLASSIFICATION Brown silty fine to medium sand with gravel (SM) Light brown silty fine to medium sand with gravel (SM) Reddish brown silty fine sand {SM) 0.001 GeoENGINEERs_Q' APPENDIXC REPORT LIM/TA TIONS AND GUIDELINES FOR USE t • APPENDIX C REPORT LIMITATIONS AND GUIDELINES FOR USE' This appendix provides information to help you manage your nsks 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 for the Talbot Hill Access Roads project. 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 engmeer or architect may not fulfill the needs of a construction contractor or even another civII 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 our Client. 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 the Client 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 Talbot Hill Access Roads project in Renton, Washington. GcoEnginecrs 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 structure; • elevation, configuration, location, orientation or weight of the proposed structure; • composition of the design team; or • project ownership. If important changes are made after the date of this report, Geo Engineers should be given the opportunity to review our interpretations and recommendations and provide written modifications or confirmation, as appropriate. 1 Developed based on material provided by ASFE, Professional Finns Practicing in the Geosciences; www.asfe.org . File No. 0186-710-01 J11ly 11' ]007 Page C-1 GEOENGINEER~ SUBSURFACE CONDITIONS CAN CHANGE This geotechmcal or geologic report is based on conditions that existed at the time the study was performed. The findmgs and conclusions of this report may be affected by the passage of time, by manmade events such as construct10n on or adJacent to the site, or by natural events such as floods, earthquakes, slope instability or groundwater fluctuations. Always contact GeoEngrneers before applying a report to determme if it remains applicable. MOST GEOTECHNICAL AND GEOLOGIC FINDINGS ARE PROFESSIONAL OPINIONS Our interpretat10ns 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 GeoEngmeers' 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 engmeering or geologic report. Reduce that risk by having GeoEngineers participate in pre-bid and preconstruction conferences, and by providing construction observation. Do Nor REDRAW THE EXPLORATION LOGS Geotechnical engineers and geologists prepare final boring and testing 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. Fiieiv'o 0/86-710-0/ July 11. 1007 Page C-2 GEOENGiNEER~ 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 geotechmca] engineermg or geolog1c report. but preface it with a clearly wntten 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 responsihtlities stemming from unanticipated conditions. Further, a contingency for unanticipated conditions should be mcluded in your project budget and schedule. CONTRACTORS ARE RESPONSIBLE FOR SITE SAFETY ON THEIR OWN CONSTRUCTION PROJECTS Our geotechnica! 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 disciplmes. This lack of understanding can create umealistic 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 "B10logical 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. File No. 0/86-7/0-01 July II. 2007 Page C-3 GEOENGINEER~