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HomeMy WebLinkAboutRS_Technical_Information_Report_221208_v1 800 Garden Technical Information Report May 2022 | Master Site Plan TIR Report May 2022 | Master Site Plan TIR Report December 2022 800 Garden – Bay West i Technical Information Report May 2022 Prepared for: Bay West Prepared by: KPFF Consulting Engineers 1601 Fifth Avenue, Suite 1600 Seattle, WA 98101 Phone: (206) 622-5822 KPFF Project No. 2000705 FOR REFERENCE ONLY December 2022 KPFF Consulting Engineers ii 800 Garden – Bay West iii Table of Contents 1. Project Overview ........................................................................................................................................... 1 2. Conditions and Requirements Summary ................................................................................................... 2 Core Requirement No. 1: Discharge at the Natural Location ........................................................................ 2 Core Requirement No. 2: Off-Site Analysis ................................................................................................... 2 Core Requirement No. 3: Flow Control .......................................................................................................... 2 Core Requirement No. 4: Conveyance System ............................................................................................. 3 Core Requirement No. 5: Construction stormwater pollution prevention ...................................................... 3 Core Requirement No. 6: Maintenance and Operations ............................................................................... 3 Core Requirement No. 7: Financial Guarantees and Liability ....................................................................... 3 Core Requirement No. 8: Water Quality facilities .......................................................................................... 3 Core Requirement No. 9: On-Site BMPs ....................................................................................................... 3 Special Requirements ..................................................................................................................................... 4 Special Requirement No. 1: Other Adopted Area-Specific Requirements .............................................. 4 Special Requirement No. 2: Flood Hazard Area Delineation .................................................................. 4 Special Requirement No. 3: Flood Protection Facilities .......................................................................... 4 Special Requirement No. 4: Source Control ........................................................................................... 4 Special Requirement No. 5: Oil Control .................................................................................................. 4 Special Requirement No. 6: Aquifer Protection Area .............................................................................. 4 3. Off-Site Analysis ........................................................................................................................................... 4 Bacteria Problem (Type 1) .............................................................................................................................. 5 Dissolved Oxygen (DO) Problem (Type 2) ..................................................................................................... 5 Temperature Problem (Type 3) ...................................................................................................................... 5 4. Flow Control, LID, and Water Quality Facility Analysis and Design ....................................................... 5 Existing Site Hydrology ................................................................................................................................... 5 Developed Site Hydrology .............................................................................................................................. 5 Performance Standards .................................................................................................................................. 6 Flow Control System ....................................................................................................................................... 6 Water Quality System ..................................................................................................................................... 6 5. Conveyance System Analysis and Design................................................................................................. 6 6. Special Reports and Studies ....................................................................................................................... 6 7. Other Permits ................................................................................................................................................ 7 8. Construction Stormwater Pollution Prevention Plan (CSWPPP) Analysis and Design ........................ 7 Erosion and Sediment Control Plan Analysis and Design .............................................................................. 7 Stormwater Pollution Prevention and Spill Control Plan Design .................................................................... 7 9. Bond Quantities, Facility Summaries, and Declaration of Covenant ...................................................... 7 10. Operations and Maintenance Manual ......................................................................................................... 7 KPFF Consulting Engineers iv List of Figures Figure 1-1: Vicinity Map (Renton GIS)................................................................................................................. 1 List of Tables Table 1-1: Summary of Site Areas ...................................................................................................................... 1 Table 7-1: List of Permits ..................................................................................................................................... 7 Appendices Appendix A – Site Figures Appendix B – Technical Information Report (TIR) Worksheet Appendix C – Geotechnical Report Appendix D – Project Plans Appendix E - Correspondence 800 Garden – Bay West 1 1. Project Overview The 800 Garden project is located at 800 Garden Avenue North, Renton, Washington (King County Parcel ID No. 0823059217). It is bounded by Northeast Eighth Street to the south, Garden Avenue to the west, a railroad to the east, and a home improvement center to the north, refer to figure 1-1 below for a general site vicinity map. The proposed project consists of three residential buildings with ground-level retail. Between the buildings will be pedestrian-oriented plazas with landscaping and concrete paths. Off-site improvements in the public right-of-way include street widening, concrete curbs, landscaping strips, concrete sidewalks, concrete driveway, ADA curb ramps, and additional property dedicated to the City of Renton (COR). Refer to Table 1-1 below for a summary of the proposed and existing site areas. Figure 1-1: Vicinity Map (Renton GIS) Table 1-1: Summary of Site Areas LAND COVER EXISTING PROPOSED Building Area (Square Feet) 157,870 325,170 Impervious Site Area (Square Feet) 328,360 149,704 Pervious Site Area (Square Feet) 45,899 57,255 Total Site Area (Square Feet) 532,129 532,129 Total Impervious Area (Square Feet) 486,230 474,874 Percent Impervious 91.2% 89.2% KPFF Consulting Engineers 2 The site currently contains a one-story commercial building, asphalt parking lot, two driveways, concrete pedestrian walkways, and landscaping. The existing site is generally flat. There is an existing short retaining wall along the east side that separates the fire lane from the railroad. In the existing condition, stormwater from the parking lot sheet flows to catch basins spaced throughout the lot. These catch basins connect to a system that discharges stormwater to the 72-inch public storm drain in Garden Avenue. Stormwater from the roof and access drives along the east and south sides of the existing building are conveyed to the north where stormwater connects with the parking lot drainage and discharges near the middle of the site. The proposed development will discharge to the same existing stormwater conveyance systems in Garden Avenue North. New pollution-generating surfaces will be treated using Best Management Practices (BMPs) that meet enhanced basic water quality standards. Refer to Appendix A for Land coverage exhibits, basin exhibits, site exhibits, and Appendix B for the TIR worksheet. 2. Conditions and Requirements Summary The proposed redevelopment project results in more than 2,000 square feet but less than 50 acres of new plus replaced impervious surface; therefore, a “Full Drainage Review” is required per the 2017 City of Renton Surface Water Design Manual (CORSWDM), Section 1.1.2.4. The following is a summary of how the project will comply with the nine core requirements and six special requirements. CORE REQUIREMENT NO. 1: DISCHARGE AT THE NATURAL LOCATION The Project will generally maintain the existing topography and drainage patterns of the site. Runoff from the project site will continue to discharge to the existing public stormwater system in Garden Avenue. Stormwater runoff from the frontage improvements will not be redirected as a result of this project. The on-site drainage facilities are not anticipated to create a significant adverse impact to downstream properties or drainage systems. CORE REQUIREMENT NO. 2: OFF-SITE ANALYSIS An off-site analysis is included in Section 3 of this report, as required by Section 1.2.2 of the CORSWDM. CORE REQUIREMENT NO. 3: FLOW CONTROL The project will continue to discharge directly to Johns Creek via the 72-inch public storm drain in Garden Avenue adjacent to the site. The site and discharge path are located downstream of the Interstate 405 east right-of-way. Per Section 1.2.3 and Table 1.2.3.B if the CORSWDM, Johns Creek has been identified as a major receiving water. Coordination with the City of Renton, included in Appendix E, has determined that the current conveyance system has sufficient capacity for the project and there are no erosion concerns with Johns Creek. Furthermore, the project will be reducing the amount of impervious area draining to Johns Creek; as such, the project does not anticipate adverse impacts due to the development. 800 Garden – Bay West 3 As such, flow control will not be required as part of the proposed development. CORE REQUIREMENT NO . 4: CONVEYANCE SYSTEM Proposed conveyance system elements on-site and off-site shall be analyzed, designed, and constructed per Section 1.2.4 of the CORSWDM. Conveyance system calculations will be provided during construction document permitting following entitlement. CORE REQUIREMENT NO. 5: CONSTRUCTION STORMWATER POLLUTION PREVENTION Temporary Erosion and Sediment Control (TESC) BMPs will be implemented during construction to prevent the transport of sediment from the project site to the maximum extent feasible. TESC BMPs are anticipated to include silt fences, conveyance swales, check dams, a sediment pond with a liner, catch basin inserts, mulching of exposed areas, dust control, and other measures as necessary. A Construction Stormwater Pollution Prevention Plan (CSWPPP) will be prepared during construction document permitting following entitlement. CORE REQUIREMENT NO. 6: MAINTENANCE AND OPER ATIONS The owner is responsible for the maintenance and operations of the proposed drainage facilities. A maintenance and operations manual will be provided during construction document permitting following entitlement. CORE REQUIREMENT NO. 7: FINANCIAL GUARANTEES AND LIABILITY The project will post a construction bond, assignment of funds, or a certified check before a building permit is issued in accordance with the COR Municipal Code 4-6-030. The applicant will also maintain liability insurance throughout the duration of construction. A maintenance bond will also be submitted to the COR before receiving acceptance of any newly constructed on-site private storm drain improvements. Bond quantities will be provided during construction document permitting following entitlement. CORE REQUIREMENT NO. 8: WATER QUALITY FACILITIES The project generates more than 5,000 square feet of pollution-generating impervious surfaces (PGIS) with greater than 50 percent of the site’s runoff to the water quality facility being from commercial land use; therefore, Enhanced Basic Water Quality is required per Section 1.2.8.1 of the CORSWDM. The project will treat runoff from target PGIS using a series of proprietary water quality vaults. See Section 4 of this report for the project’s water quality system. CORE REQUIREMENT NO. 9: ON-SITE BMPS The site is greater than 22,000 square feet; therefore, the project is subject to Large Lot BMP Requirements per Section 1.2.9.2 of the CORSWDM. On-site BMP requirements may be satisfied through two methods: (1) application of BMPs to the maximum extent feasible, or (2) complying with the Low-Impact Development (LID) Performance Standard. The project opts to satisfy Core Requirement No. 9 by applying BMPs to the maximum extent feasible for all new and replaced impervious surfaces and new pervious surfaces. KPFF Consulting Engineers 4 The project will evaluate the feasibility for the specific BMPs during construction document permitting following entitlement. Soil amendment will be applied to all new pervious surfaces in accordance with Appendix C.2.13 of the CORSWDM. Roof downspout connects to the public stormwater system will be via perforated pipe connection in accordance with Appendix C.2.11 of the CORSWM. SPECIAL REQUIREMENTS In addition to the nine core requirements, the project must evaluate compliance with the six special drainage requirements. Special Requirement No. 1: Other Adopted Area-Specific Requirements There are no known adopted area-specific regulations for the site; therefore, Special Requirement No. 1 is not applicable. Special Requirement No. 2: Flood Hazard Area Delineation Per the FEMA Flood Map Service Center, the project does not contain and is not adjacent to a flood hazard area; therefore, Special Requirement No. 2 is not applicable. Special Requirement No. 3: Flood Protection Facilities The project will not rely on existing or proposed flood protection facilities for protection against hazards posed by erosion or inundation; therefore, Special Requirement No. 3 is not applicable. Special Requirement No. 4: Source Control Water quality source controls applicable to this project will be applied in accordance with the King County Stormwater Pollution Prevention Manual and Renton Municipal Code, Title IV. See Section 8 of this report for the Construction Stormwater Pollution Prevention Plan Analysis and Design. Special Requirement No. 5: Oil Control The site is not considered high use because its anticipated average daily traffic count is less than 100 vehicles per 1,000 square feet of gross building area; therefore, Special Requirement No. 5 is not applicable. Special Requirement No. 6: Aquifer Protection Area The site is not located within the Aquifer Protection Areas; therefore, Special Requirement No. 6 is not applicable. 3. Off-Site Analysis Per Section 1.2.2 of the CORSWDM, projects shall perform an off-site analysis to assess potential off-site drainage and water quality impacts associated with the development of the project site. Per the exemptions laid out in Section 1.2.2 of the CORSWDM, the project meets criteria 2; the project results in a net reduction of impervious surface and does not exceed 3/4 acre of new pervious surface and utilizes an existing connection to discharge to the existing 72-inch storm main. The project does not contain or is located adjacent to an area identified as being a landslide hazard, steep slope hazard area, or erosion hazard area. However, the project triggers Core Requirement No. 8 (Water Quality Facilities) – as such, the project will 800 Garden – Bay West 5 provide an off-site analysis sufficient to identify and address downstream water quality problems requiring special attention per Section 1.2.2.1.2 of the CORSWDM. Per the Washington Department of Ecology (DOE) Water Quality Atlas, Johns Creek has been identified as Category 5 for temperature, bacteria, and dissolved oxygen. BACTERIA PROBLEM (TYPE 1) The project will evaluate treatment methods to be implemented during construction document permitting following entitlement. DISSOLVED OXYGEN (DO) PROBLEM (TYPE 2) The project is not proposing to utilize a wetpool, wetpond, or a wetvault to manage stormwater. No additional facilities are proposed to address dissolved oxygen. TEMPERATURE PROBLEM (TYPE 3) The project is not proposing to utilize a wetpond to provide water quality, and the project is not proposing open drainage features. No additional facilities are proposed to address water temperature. 4. Flow Control, LID, and Water Quality Facility Analysis and Design EXISTING SITE HYDROLOGY The project consists of one threshold discharge area; the parking lot and building all drain to the existing 72- inch storm main under Garden Avenue. Surface stormwater in the parking lot sheet flows to a series of catch basins spaced throughout the lot. Stormwater is conveyed to the west where it discharges to the public storm drain. Surface stormwater from the access road along the west, east, and south sides of the building sheet flows to catch basins, which then conveys stormwater to the southwest corner of the site where stormwater discharges to the existing public storm drain. Stormwater from the roof connects to the southerly stormwater system prior to discharging to the public storm main. Refer to Appendix A for an existing conditions basin exhibit. DEVELOPED SITE HYDROLOGY The development will consist of one threshold discharge area made up of three buildings, an access road along the north and east perimeter of the site, and large pedestrian-oriented plazas between the buildings and on the southwest corner of the site. Runoff from the PGIS drive aisles around the site will be conveyed to water quality facilities designed to provide enhanced water quality treatment and sized for all surface areas draining to the facility. Refer to Appendix A for a proposed conditions basin exhibit. KPFF Consulting Engineers 6 PERFORMANCE STANDARD S The project is exempt from flow control as discussed in Section 2, Core Requirement No. 3 of this report. On-site BMPs will be implemented to the maximum extent feasible per the Large Lot BMP Requirements in Section 1.2.9.2.2 of the CORSWDM. The conveyance system will have sufficient capacity to convey and contain the 25-year peak flow per Section 1.2.4 of the CORSWDM. The project is subject to Enhanced Basic Water Quality per Section 1.2.8.1 of the CORSWDM. FLOW CONTROL SYSTEM The project is exempt from flow control as discussed in Section 2, Core Requirement No. 3 of this report. WATER QUALITY SYSTEM All new PGIS and surfaces adjacent to and downstream of the PGIS will be directed to a below-grade water quality vault. The project will evaluate the various emerging stormwater treatment technologies that have received DOE General Use Level Designation approval for at minimum enhanced water quality treatment. The facility will be sized to provide treatment for 91 percent of the total PGIS runoff volume to comply with Core Requirement No. 8. 5. Conveyance System Analysis and Design No existing capacity issues were found in the off-site analysis as discussed in Section 3 of this report; therefore, existing off-site conveyance systems are not analyzed. All new on-site and off-site conveyance system elements shall be analyzed, designed, and constructed per Section 1.2.4.1 of the CORSWDM. Conveyance system calculations will be provided during construction document permitting following entitlement. 6. Special Reports and Studies A Geotechnical Engineering Report has been prepared by GeoEngineers dated March 10, 2022. Refer to Appendix C for a detailed analysis of the site explorations and existing soils. 800 Garden – Bay West 7 7. Other Permits Section 1.1.3 of the CORSWDM provides other required permits for the project, which are included in the table below. Table 7-1: List of Permits Agency Permit/Approval Washington State Department of Ecology NPDES Construction Stormwater permit City of Renton Civil Construction Permit Clearing, Grading, and Building Permits 8. Construction Stormwater Pollution Prevention Plan (CSWPPP) Analysis and Design EROSION AND SEDIMENT CONTROL PLAN ANALYSIS AND DESIGN Temporary and permanent erosion and sediment control (ESC) measures will be implemented per Section D.2.1 of the CORSWDM. A CSWPPP will be prepared during construction document permitting following entitlement. STORMWATER POLLUTION PREVENTION AND SPILL CONTROL PLAN DESIGN Stormwater pollution prevention and spill control (SWPPS) measures will be implemented per Section D.2.2 of the CORSWDM. A CSWPPP will be prepared during construction document permitting following entitlement. 9. Bond Quantities, Facility Summaries, and Declaration of Covenant The Site Improvement Bond Quantity Worksheet provided by the Community of Economic Development (CED) will be prepared during construction document permitting following entitlement. 10. Operations and Maintenance Manual The stormwater facilities located on-site generally consist of catch basins for collection; storm drainage pipes for conveyance; infiltrating bioretention planters for water quality treatment; stormwater structures including manholes, a flow splitter, and a pump; and rock splash pads for outfall protection. The Maintenance and Operations Manual is intended for the project owner once the project is complete and will be prepared during construction document permitting following entitlement, in accordance with Appendix A of the CORSWDM. KPFF Consulting Engineers 8 This page intentionally left blank. 800 Garden – Bay West Appendix A Appendix A Site Figures  CSK-A1 – Existing Drainage Areas  CSK-A2 – Proposed Drainage Areas  CSK-A3 – Existing Drainage Basin  CSK-A4 – Proposed Drainage Basin  CSK-A5 – Off-site Analysis Discharge Map  CSK-A6 – NRCS Soil Map STOPSTOPSTOP STOP STOPSTOPSTOP STOP NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE STOPSTOP STOPNO P AR KI NG FI RE L AN E NO P ARK IN G F IR E L ANENO PA RK IN G F IR E LA NE STOP STOPSTOPSTOP STOP STOPSTOPSTOP STOP NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE STOPSTOP STOPNO P AR KI NG F I RE L AN E NO PA RK IN G F IR E LA NENO PA RK IN G F IR E LA NE STOP STOPSTOPSTOP STOP STOPSTOPSTOP STOP NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE STOPSTOP STOPNO P AR KI NG F I RE L AN E NO PA RK IN G F IR E LA NENO PA RK IN G F IR E LA NE STOP STOPSTOPSTOPSTOPSTOP NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE STOPSTOP 9,028 752 City of Renton Print map Template This map is a user generated static output from an Internet mapping site and is for reference only. Data layers that appear on this map may or may not be accurate, current, or otherwise reliable. None 3/10/2022 Legend 5120256 THIS MAP IS NOT TO BE USED FOR NAVIGATION Feet Notes 512 WGS_1984_Web_Mercator_Auxiliary_Sphere Information Technology - GIS RentonMapSupport@Rentonwa.gov Streams (Classified) <all other values> Type S Shoreline Type F Fish Type Np Non-Fish Type Ns Non-Fish Seasonal Unclassified Not Visited 5' Primary 5' Intermediate 2019.sid Red: Band_1 Green: Band_2 Blue: Band_3 N I-405DISCHARGE POINT PROJECT SITE JOHNS CREEK 0.25 MILE DOWNSTREAM ~0.57 MILE DOWNSTREAM GARDEN AVE N N 8TH ST LAKE WASHINGTON Off-site Analysis Discharge Map CSK-A5 Soil Map—King County Area, Washington Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 3/21/2022 Page 1 of 3526040052606005260800526100052612005261400526160052604005260600526080052610005261200526140052616005261800559100559300559500559700559900560100560300560500560700560900561100561300561500 559100 559300 559500 559700 559900 560100 560300 560500 560700 560900 561100 561300 561500 47° 30' 24'' N 122° 13' 0'' W47° 30' 24'' N122° 10' 56'' W47° 29' 37'' N 122° 13' 0'' W47° 29' 37'' N 122° 10' 56'' WN Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 10N WGS84 0 300 600 1200 1800 Feet 0 100 200 400 600 Meters Map Scale: 1:6,980 if printed on B landscape (17" x 11") sheet. Soil Map may not be valid at this scale. Project Location CSK-A6 Soil group "Ur" MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Map Unit Polygons Soil Map Unit Lines Soil Map Unit Points Special Point Features Blowout Borrow Pit Clay Spot Closed Depression Gravel Pit Gravelly Spot Landfill Lava Flow Marsh or swamp Mine or Quarry Miscellaneous Water Perennial Water Rock Outcrop Saline Spot Sandy Spot Severely Eroded Spot Sinkhole Slide or Slip Sodic Spot Spoil Area Stony Spot Very Stony Spot Wet Spot Other Special Line Features Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:24,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: King County Area, Washington Survey Area Data: Version 17, Aug 23, 2021 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Jul 6, 2020—Jul 27, 2020 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. Soil Map—King County Area, Washington Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 3/21/2022 Page 2 of 3 CSK-A6 Map Unit Legend Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI AgC Alderwood gravelly sandy loam, 8 to 15 percent slopes 8.4 1.9% AkF Alderwood and Kitsap soils, very steep 36.7 8.2% InC Indianola loamy sand, 5 to 15 percent slopes 54.1 12.1% RdC Ragnar-Indianola association, sloping 25.0 5.6% RdE Ragnar-Indianola association, moderately steep 10.9 2.4% Ur Urban land 279.0 62.4% Totals for Area of Interest 447.1 100.0% Soil Map—King County Area, Washington Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 3/21/2022 Page 3 of 3 CSK-A6 REFERENCE 8: PLAN REVIEW FORMS AND WORKSHEET TECHNICAL INFORMATION REPORT (TIR) WORKSHEET 12/12/2016 2017 City of Renton Surface Water Design Manual 8-A-6 Part 17 SIGNATURE OF PROFESSIONAL ENGINEER I, or a civil engineer under my supervision, have visited the site. Actual site conditions as observed were incorporated into this worksheet and the attached Technical Information Report. To the best of my knowledge the information provided here is accurate. ____________________________________________________________________________________ Signed/Date 800 Garden – Bay West Appendix B Appendix B Technical Information Report (TIR) Worksheet CITY OF RENTON SURFACE WATER DESIGN MANUAL 2017 City of Renton Surface Water Design Manual 12/12/2016 8-A-1 REFERENCE 8-A TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 1 PROJECT OWNER AND PROJECT ENGINEER Part 2 PROJECT LOCATION AND DESCRIPTION Project Owner _____________________________ Phone ___________________________________ Address __________________________________ _________________________________________ Project Engineer ___________________________ Company _________________________________ Phone ___________________________________ Project Name __________________________ CED Permit # ________________________ Location Township ________________ Range __________________ Section _________________ Site Address __________________________ _____________________________________ Part 3 TYPE OF PERMIT APPLICATION Part 4 OTHER REVIEWS AND PERMITS  Land Use (e.g., Subdivision / Short Subd.)  Building (e.g., M/F / Commercial / SFR)  Grading  Right-of-Way Use  Other _______________________  DFW HPA  COE 404  DOE Dam Safety  FEMA Floodplain  COE Wetlands  Other ________  Shoreline Management  Structural Rockery/Vault/_____  ESA Section 7 Part 5 PLAN AND REPORT INFORMATION Technical Information Report Site Improvement Plan (Engr. Plans) Type of Drainage Review (check one): Date (include revision dates): Date of Final:  Full  Targeted  Simplified  Large Project  Directed ____________________________________ __________________ Plan Type (check one): Date (include revision dates): Date of Final:  Full  Modified  Simplified ____________________________________ __________________ Bay West Development 1725 South Bascin Ave, Suite 1050 Campbell, CA 95008 Thaddeus Egging KPFF Consulting Engineers 206-622-5822 408-781-0561 800 Garden 23 north 5 east 8 800 Garden Avenue North Renton, WA 98057 ü ü REFERENCE 8: PLAN REVIEW FORMS AND WORKSHEET TECHNICAL INFORMATION REPORT (TIR) WORKSHEET 12/12/2016 2017 City of Renton Surface Water Design Manual 8-A-2 Part 6 SWDM ADJUSTMENT APPROVALS Type (circle one): Standard / Blanket Description: (include conditions in TIR Section 2) ____________________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________ Approved Adjustment No. ______________________ Date of Approval: _______________________ Part 7 MONITORING REQUIREMENTS Monitoring Required: Yes / No Start Date: _______________________ Completion Date: _______________________ Describe: _________________________________ _________________________________________ _________________________________________ Re: SWDM Adjustment No. ________________ Part 8 SITE COMMUNITY AND DRAINAGE BASIN Community Plan: ____________________________________________________________________ Special District Overlays: ______________________________________________________________ Drainage Basin: _____________________________________________________________________ Stormwater Requirements: _____________________________________________________________ Part 9 ONSITE AND ADJACENT SENSITIVE AREAS  River/Stream ________________________  Lake ______________________________  Wetlands ____________________________  Closed Depression ____________________  Floodplain ___________________________  Other _______________________________ _______________________________  Steep Slope __________________________  Erosion Hazard _______________________  Landslide Hazard ______________________  Coal Mine Hazard ______________________  Seismic Hazard _______________________  Habitat Protection ______________________  _____________________________________ N/A N/A Johns Creek REFERENCE 8-A: TECHNICAL INFORMATION REPORT (TIR) WORKSHEET TECHNICAL INFORMATION REPORT (TIR) WORKSHEET 2017 City of Renton Surface Water Design Manual 12/12/2016 Ref 8-A-3 Part 10 SOILS Soil Type ______________________ ______________________ ______________________ ______________________ Slopes ________________________ ________________________ ________________________ ________________________ Erosion Potential _________________________ _________________________ _________________________ _________________________  High Groundwater Table (within 5 feet)  Other ________________________________  Sole Source Aquifer  Seeps/Springs  Additional Sheets Attached Part 11 DRAINAGE DESIGN LIMITATIONS REFERENCE  Core 2 – Offsite Analysis_________________  Sensitive/Critical Areas__________________  SEPA________________________________  LID Infeasibility________________________  Other________________________________  _____________________________________ LIMITATION / SITE CONSTRAINT _______________________________________ _______________________________________ _______________________________________ _______________________________________ _______________________________________ _______________________________________  Additional Sheets Attached Part 12 TIR SUMMARY SHEET (provide one TIR Summary Sheet per Threshold Discharge Area) Threshold Discharge Area: (name or description) Core Requirements (all 8 apply): Discharge at Natural Location Number of Natural Discharge Locations: Offsite Analysis Level: 1 / 2 / 3 dated:__________________ Flow Control (include facility summary sheet) Standard: _______________________________ or Exemption Number: ____________ On-site BMPs: _______________________________ Conveyance System Spill containment located at: _____________________________ Erosion and Sediment Control / Construction Stormwater Pollution Prevention CSWPP/CESCL/ESC Site Supervisor: _____________________ Contact Phone: _________________________ After Hours Phone: _________________________ Ur - Urban Land ~0%-4%Uncategorized 1 1 Direct Discharge TBD by Contractor REFERENCE 8: PLAN REVIEW FORMS AND WORKSHEET TECHNICAL INFORMATION REPORT (TIR) WORKSHEET 12/12/2016 2017 City of Renton Surface Water Design Manual 8-A-4 Part 12 TIR SUMMARY SHEET (provide one TIR Summary Sheet per Threshold Discharge Area) Maintenance and Operation Responsibility (circle one): Private / Public If Private, Maintenance Log Required: Yes / No Financial Guarantees and Liability Provided: Yes / No Water Quality (include facility summary sheet) Type (circle one): Basic / Sens. Lake / Enhanced Basic / Bog or Exemption No. _______________________ Special Requirements (as applicable): Area Specific Drainage Requirements Type: SDO / MDP / BP / Shared Fac. / None Name: ________________________ Floodplain/Floodway Delineation Type (circle one): Major / Minor / Exemption / None 100-year Base Flood Elevation (or range): _______________ Datum: Flood Protection Facilities Describe: Source Control (commercial / industrial land use) Describe land use: Describe any structural controls: Oil Control High-Use Site: Yes / No Treatment BMP: _________________________________ Maintenance Agreement: Yes / No with whom? _____________________________________ Other Drainage Structures Describe: Will be provided at constructiondocument permitting Will be provided at constructiondocument permitting REFERENCE 8-A: TECHNICAL INFORMATION REPORT (TIR) WORKSHEET TECHNICAL INFORMATION REPORT (TIR) WORKSHEET 2017 City of Renton Surface Water Design Manual 12/12/2016 Ref 8-A-5 Part 13 EROSION AND SEDIMENT CONTROL REQUIREMENTS MINIMUM ESC REQUIREMENTS DURING CONSTRUCTION  Clearing Limits  Cover Measures  Perimeter Protection  Traffic Area Stabilization  Sediment Retention  Surface Water Collection  Dewatering Control  Dust Control  Flow Control  Control Pollutants  Protect Existing and Proposed BMPs/Facilities  Maintain Protective BMPs / Manage Project MINIMUM ESC REQUIREMENTS AFTER CONSTRUCTION  Stabilize exposed surfaces  Remove and restore Temporary ESC Facilities  Clean and remove all silt and debris, ensure operation of Permanent BMPs/Facilities, restore operation of BMPs/Facilities as necessary  Flag limits of sensitive areas and open space preservation areas  Other _______________________ Part 14 STORMWATER FACILITY DESCRIPTIONS (Note: Include Facility Summary and Sketch) Flow Control Type/Description Water Quality Type/Description  Detention  Infiltration  Regional Facility  Shared Facility  On-site BMPs  Other ________________ ________________ ________________ ________________ ________________ ________________  Vegetated Flowpath  Wetpool  Filtration  Oil Control  Spill Control  On-site BMPs  Other ________________ ________________ ________________ ________________ ________________ ________________ ________________ Part 15 EASEMENTS/TRACTS Part 16 STRUCTURAL ANALYSIS  Drainage Easement  Covenant  Native Growth Protection Covenant  Tract  Other ____________________________  Cast in Place Vault  Retaining Wall  Rockery > 4′ High  Structural on Steep Slope  Other _______________________________ Will be provided at construction document permitting 800 Garden – Bay West Appendix C Appendix C Geotechnical Report Geotechnical Engineering Services 800 Garden Mixed-Use 800 Garden Avenue North Renton, Washington for Bay West Development Holdings, LLC March 10, 2022 Geotechnical Engineering Services 800 Garden Mixed-Use 800 Garden Avenue North Renton, Washington for Bay West Development Holdings, LLC March 10, 2022 GeoEngineers, Inc. Redmond, Washington 98052 425.861.6000 Geotechnical Engineering Services 800 Garden Mixed-Use 800 Garden Avenue North Renton, Washington File No. 24939-001-00 March 10, 2022 Prepared for: Bay West Development Holdings, LLC 1725 S. Bascom Avenue, Suite 1050 Campbell, California 95008 Attention: Pete Beritzhoff Prepared by: GeoEngineers, Inc. 17425 NE Union Hill Road, Suite 250 Redmond, Washington 98052 425.861.6000 Corey A. Hamil, PE Kyle M. Smith, PE Geotechnical Engineer Senior Geotechnical Engineer Robert C. Metcalfe, PE, LEG Principal CAH:KMS:RCM:nld 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. March 10, 2022 | Page i File No. 24939-001-00 1.0 INTRODUCTION ......................................................................................................................................... 1 2.0 PROJECT DESCRIPTION ............................................................................................................................ 1 3.0 FIELD EXPLORATIONS AND LABORATORY TESTING .............................................................................. 1 3.1. Field Explorations ................................................................................................................................... 1 3.2. Laboratory Testing ................................................................................................................................. 1 3.3. Previous Geotechnical Studies ............................................................................................................. 1 4.0 SITE CONDITIONS ...................................................................................................................................... 2 4.1. Site Geology ........................................................................................................................................... 2 4.2. Surface Conditions................................................................................................................................. 2 4.3. Subsurface Soil Conditions ................................................................................................................... 2 4.4. Groundwater Conditions ........................................................................................................................ 3 5.0 CONCLUSIONS AND RECOMMENDATIONS ............................................................................................. 3 5.1. Earthquake Engineering ........................................................................................................................ 4 5.1.1. Site-Specific Response Spectrum ............................................................................................. 4 5.1.2. Seismic Hazards ......................................................................................................................... 5 5.2. Building Foundations ............................................................................................................................. 6 5.2.1. Augercast Piles ........................................................................................................................... 6 5.3. Footing Drains ........................................................................................................................................ 9 5.4. Floor Slabs .............................................................................................................................................. 9 5.4.1. Design Features ...................................................................................................................... 10 5.5. Methane Collection ............................................................................................................................. 10 5.5.1. Methane Barrier ...................................................................................................................... 10 5.5.2. Vent Pipe System .................................................................................................................. 11dr 5.6. Underslab Utility Support .................................................................................................................... 11 5.7. Hardscape and Utilities ...................................................................................................................... 11 5.8. Earthwork ............................................................................................................................................ 12 5.8.1. Clearing and Site Preparation ................................................................................................. 12 5.8.2. Subgrade Preparation ............................................................................................................. 12 5.8.3. Subgrade Protection ................................................................................................................ 13 5.8.4. Structural Fill............................................................................................................................ 13 5.8.5. Temporary Cut Slopes ............................................................................................................. 16 5.8.6. Erosion and Sediment Control ................................................................................................ 16 5.8.7. Utility Trenches ........................................................................................................................ 17 5.9. Pavement Recommendations ............................................................................................................ 17 5.9.1. Subgrade Preparation ............................................................................................................. 17 5.9.2. New Hot Mix Asphalt Pavement ............................................................................................. 17 5.9.3. Portland Cement Concrete Pavement .................................................................................... 17 5.9.4. Asphalt-Treated Base .............................................................................................................. 18 5.10. Construction Dewatering .................................................................................................................... 18 5.11. Infiltration Considerations .................................................................................................................. 19 6.0 RECOMMENDED ADDITIONAL GEOTECHNICAL SERVICES .................................................................. 19 7.0 LIMITATIONS ........................................................................................................................................... 19 8.0 REFERENCES .......................................................................................................................................... 20 March 10, 2022 | Page ii File No. 24939-001-00 LIST OF FIGURES Figure 1. Vicinity Map Figure 2. Site Plan Figure 3. Bearing Soils Contour Map Figure 4. Cross Section A-A’ Figure 5. Cross Section B-B’ Figure 6. Cross Section C-C’ Figure 7. Wall Drainage and Backfill Figure 8. Compaction Criteria for Trench Backfill Figure 9. Recommended Site-Specific MCER Response Spectrum APPENDICES Appendix A. Field Explorations Figure A-1 – Key to Exploration Logs Figures A-2 through A-5 – Log of Borings Figure A-6 through A-13 – CPT Logs Appendix B. Laboratory Testing Figure B-1 – Atterberg Limits Test Results Appendix C. Boring Logs from Previous Studies Appendix D. Report Limitations and Guidelines for Use March 10, 2022 | Page 1 File No. 24939-001-00 1.0 INTRODUCTION This geotechnical engineering report presents the preliminary results of GeoEngineers’ geotechnical engineering services for the 800 Garden Mixed-Use development located at 800 Garden Avenue North in Renton, Washington. The site consists of approximately 11.5 acres (King County Parcel No. 082305-9217) and is located northeast of the Garden Avenue North and North 8th Street intersection. The site is currently occupied by a Fry’s Electronics warehouse building and at-grade asphalt paved surface parking lots. The site is shown relative to surrounding physical features on Figure 1, Vicinity Map and Figure 2, Site Plan. The purpose of this report is to provide geotechnical engineering conclusions and recommendations for the design of the planned 800 Garden Mixed-use development. GeoEngineers’ geotechnical engineering services have been completed in general accordance with our signed agreement executed on January 8, 2021. 2.0 PROJECT DESCRIPTION Based on our review of the Pre-Application Submittal, dated November 11, 2021, we understand Bay West Development is planning a new development that includes demolition of the Fry’s Electronics building and construction of three new buildings to be completed in three phases. Phase 1 or Building A consists of five stories of Type III-A timber construction over three levels of Type 1-A concrete construction. Phases 2 and 3, Buildings B and C, respectively, are planned to consist of five stories of Type III-A timber construction over two levels of Type 1-A concrete construction. The upper five stories of each building phase are planned to be residential housing consisting of a total of 1,223 units for the three phases. The project also includes commercial and retail space for two stories of each phased building located along Garden Avenue. Additional associated improvements include sidewalks, court yards, underground utilities, and landscaping. 3.0 FIELD EXPLORATIONS AND LABORATORY TESTING 3.1. Field Explorations Subsurface explorations at the site were evaluated by drilling four borings (B-1 through B-4) to depths of about 75 feet below existing grade and conducting eight cone penetration tests (CPT-1 through CPT-8) to depths ranging from approximately 41 to 92 feet below existing site grades. The CPTs were advanced to practical refusal. The approximate locations of the borings and CPTs are shown on Figure 2. Descriptions of the field exploration program and summary boring and CPT logs are presented in Appendix A. 3.2. Laboratory Testing Soil samples were obtained during drilling and were taken to GeoEngineers’ laboratory for further evaluation. Selected samples were tested for the determination of moisture content, fines content and Atterberg limits. A description of the laboratory testing program and the test results are presented in Appendix B. 3.3. Previous Geotechnical Studies We reviewed available geotechnical reports prepared previously by GeoEngineers and others that included subsurface information at the site or in the immediate vicinity of the site. These documents included March 10, 2022 | Page 2 File No. 24939-001-00 previous borings logs and laboratory testing for the existing Fry’s Electronics site and for the adjacent property to the north at the Lowe’s Renton site. The approximate locations of the previous boring logs we reviewed are shown in Figure 2, and are included in Appendix C. 4.0 SITE CONDITIONS 4.1. Site Geology We reviewed the geologic map of the Renton Quadrangle (Mullineaux 1965) and a U.S. Geological Survey Map titled “Geologic Map of Surficial Deposits in the Seattle 30’x60’ Quadrangle, Washington” (Youd et. Al. 1993). The surficial soils in the vicinity of the site are mapped as modified land over alluvial deposits. The modified land consists of land changes by man for construction or development purposes, generally fill methods. The alluvial deposits range from clay to gravel, with silt and fine sand most common along the Duwamish River floodplain. The alluvium is commonly organic rich, sometimes containing interbedded peat. The alluvial soils were deposited by the meandering Cedar River and are poorly to moderately consolidated. 4.2. Surface Conditions The site is currently occupied by the existing 152,000 square foot Fry’s Electronics warehouse building, which consists of a single-story prefabricated steel building. The existing Fry’s Electronics warehouse building is supported on deep foundations (augercast piles). Associated features include an asphalt paved surface parking lot to the north of the Fry’s Electronics building, access drive lanes, concrete curbing and landscaping. Site grades range from approximately Elevation 31 to 36 feet from west to east. Numerous underground utilities are located at the site including sanitary sewer, storm drain, gas, water, power, and telecommunications fiber, among others. 4.3. Subsurface Soil Conditions GeoEngineers’ understanding of subsurface conditions is based on the results of our exploration program, our review of existing geotechnical information, and our review of the geologic map. . The soils encountered at the site consist of relatively shallow fill overlying alluvial deposits as shown in Figures 4 through 6, Cross Sections A-A’ through C-C’, respectively, and the boring logs presented in Appendix A. Soils encountered at the site generally consisted of the following: ■ Asphalt: Most of the site to the north of and around the Fry’s Electronics building consists of asphalt pavement. The asphalt pavement was observed to range from approximately 3 to 11 inches thick. ■ Fill: Fill was encountered below the asphalt pavement in each of the borings and CPTs. The fill generally consisted of soft/loose to medium stiff/medium dense silt and silty sand with variable gravel content. The thickness of fill encountered in our explorations ranged from approximately 8 to 11 feet. March 10, 2022 | Page 3 File No. 24939-001-00 ■ Alluvium: Upper Alluvium The upper alluvial deposits were encountered below the fill in the borings and the cone penetration test probes. The upper alluvial deposits consist of interbedded layers of sand, silt, clay, and peat and organic silt. The upper alluvium deposit extends to depths ranging from 39 to 68 feet below existing site grades (Elevation -3 to -36 feet). The sand layers contain variable amounts of silt and are the most prevalent unit within the deposit. The sand layers are loose to medium dense, making them susceptible to liquefaction. Peat and organic silt layers within the upper alluvium vary from 3 to 15 feet thick and are highly compressible, and are generally thickest in the upper portion of the deposit. Layers of peat and organic silt are present through this deposit. The silt and clay layers are soft to medium stiff, moderately compressible, and are generally present near the bottom of this deposit. Lower Alluvium The lower alluvium deposits generally consist of medium dense to very dense sand and gravel with variable silt content. The lower alluvium deposits are considered to be generally consolidated and a suitable bearing layer for support of building foundations. The top of the lower alluvium deposit was encountered at depths ranging from 39 to 68 feet below existing site grades (Elevation -3 to -36 feet). Our interpretation of the top of the lower alluvium deposit across the site is shown on Figure 3, Bearing Soils Contour Map. 4.4. Groundwater Conditions Based on conditions observed during drilling, the groundwater level at the site ranges from approximately 7½ to 10 feet deep below existing grade, which corresponds to approximately Elevations 26.5 to 24 feet (North American Vertical Datum of 1988 [NAVD 88]). Groundwater observations are presented on the exploration logs in Appendix A at the respective depths. Our groundwater observations are consistent with previous groundwater observations and measurements taken at and in the project site vicinity. Groundwater observations represent conditions observed during exploration and may not represent the groundwater conditions throughout the year. Groundwater seepage is expected to fluctuate as a result of season, precipitation and other factors (i.e. Lake Washington water levels). 5.0 CONCLUSIONS AND RECOMMENDATIONS A summary of the 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 Site Class F per the International Building Code (IBC) due to the presence of potentially liquefiable soils below the building footprints. As a result, a site-specific seismic response spectrum is required for building periods greater than 0.5 seconds. We recommend that the building be designed using the recommended risk-targeted maximum-considered earthquake (MCER) site-specific response spectrum presented in Table 2 and Figure 9. ■ The results of our liquefaction analyses indicate that fill and loose to medium dense alluvial soils, below the groundwater table, are susceptible to liquefaction during the building code-prescribed March 10, 2022 | Page 4 File No. 24939-001-00 maximum-considered earthquake (MCE) event (i.e. earthquake event with 2,500-year return period). Based on the results of our liquefaction-induced settlement analysis, we estimate that free field ground surface settlement on the order of 2 to 10 inches could occur during an MCE-level earthquake due to soil liquefaction. ■ Foundation support for the proposed buildings can be provided by augercast piles embedded in the lower alluvial deposits. The estimated post-construction static foundation settlement of augercast piles constructed as recommended in this report, is estimated to be less than 1 inch. ■ Design of the at-grade slabs should consider estimate site settlement because of the underlying upper alluvial deposits; therefore, we recommend that the floor slabs be pile supported. In addition to being susceptible to liquefaction, the upper alluvial soils are compressible and are expected to settle under new/increased loading conditions. Static settlements will depend on the thickness of new fill placed in the building footprints. If slab areas are not supported on deep foundations, long-term static settlement is anticipated to be 4 to 6 inches. The at-grade floor slab for the building should be underlain by at least 6 inches of clean crushed rock for uniform support and as a capillary break. ■ Imported gravel borrow should be used as structural fill under all building elements. ■ We recommend that perimeter footing drains be installed around the exterior of each building. The perimeter drains should be installed at the base of the perimeter footings. ■ At-grade pavement areas may be supported on existing soils provided that the upper 2 feet of subgrade soils are removed, replaced in lifts, and compacted (if possible) to at least 95 percent of the maximum dry density (MDD) per ASTM International (ASTM) D 1557. ■ On-site fine-grained fill and alluvial soils should not be considered for reuse as structural fill and should be exported, unless used in landscape areas. Our specific geotechnical recommendations are presented in the following sections of this report. 5.1. Earthquake Engineering We evaluated the site for seismic hazards including liquefaction, lateral spreading and fault rupture. 5.1.1. Site-Specific Response Spectrum A site-specific response analysis was previously completed for the nearby Top Golf site located at 8th and Logan Avenue. A comparison of the subsurface soil conditions supports the use of the same site-specific MCER response spectrum for the 800 Garden Avenue site. The site-specific response spectrum is appropriate for building periods up to 1 second. Buildings with fundamental building periods greater than 1 second will require that a separate site-specific response analysis be completed at this site. The site-specific response analysis was completed in accordance with the procedure outlined in Chapter 21 of the American Society of Civil Engineers (ASCE) 7-10 code to develop the site-specific MCER response spectrum. The recommended MCER site-specific response spectrum is presented in Figure 9 and is defined in Table 1. The design spectrum is taken as two thirds of the MCER values presented in Table 1 per ASCE 7-10 Section 21.3. March 10, 2022 | Page 5 File No. 24939-001-00 TABLE 1. IBC SEISMIC PARAMETERS Period (s) MCER Response Spectrum (g) 0.01 0.45 0.05 0.71 0.075 0.79 0.10 0.86 0.20 1.04 0.30 1.04 0.40 1.04 0.50 1.04 0.75 1.04 1.00 1.04 5.1.2. Seismic Hazards 5.1.2.1. Surface Fault Rupture The site is located about 2.4 miles south of the Seattle Fault zone. Based on the distance from mapped known faults, it is our opinion there is a low risk of faut rupture at the site. 5.1.2.2. Liquefaction Liquefaction refers to a condition in which vibration or shaking of the ground, usually from earthquake forces, results in development of high excess pore water pressures in saturated soils and subsequent loss of stiffness and/or strength in the deposit of soil so affected. In general, soils that are susceptible to liquefaction include loose to medium dense, clean to silty sands and low-plasticity silts that are below the water table. Ground settlement, lateral spreading and/or sand boils may result from soil liquefaction. Structures, such as buildings, supported on or within liquefied soils may experience foundation settlement or lateral movement that can be damaging. The evaluation of liquefaction potential is a complex procedure and is dependent on numerous site parameters, including soil grain size, soil density, site geometry, static stress, and the design ground acceleration. Typically, the liquefaction potential of a site is evaluated by comparing the cyclic stress ratio (CSR), which is the ratio of the cyclic shear stress induced by an earthquake to the initial effective overburden stress, to the cyclic resistance ratio (CRR), which is the soils resistance to liquefaction. We evaluated the liquefaction triggering potential (Youd and Idriss 2001, Idriss and Boulanger 2014, NCEER 1998 with Cetin correction factor) and liquefaction-induced settlement (Tokimatsu and Seed 1987; Ishihara and Yoshimine 1992; Idriss and Boulanger 2008) for soil conditions in each of the borings and CPTs we completed at the site. Based on our analyses, the potential exists for liquefaction with the sandy and low plasticity silt alluvial deposits encountered in explorations completed at the site. The cohesive soils encountered within the alluvium soils may also experience loss of shear strength during seismic loading. Ground settlement resulting from earthquake-induced liquefaction is estimated to be on the order of 2 to 10 inches, with the differential settlement between column footings equal to the total estimated settlement. March 10, 2022 | Page 6 File No. 24939-001-00 5.1.2.3. Lateral Spreading Lateral spreading involves lateral displacements of large volumes of liquefied soils. Lateral spreading can occur on near-level ground as blocks of surface soils are displaced relative to adjacent blocks. Lateral spreading also occurs as blocks of surface soils are displaced toward a nearby slope or free-face such as a nearby waterfront or stream bank by movement of the underlying liquefied soil. Due to the distance to a nearby free face and the relatively flat grade, it is our opinion the risk of lateral spreading is low. 5.2. Building Foundations Based on the presence of the compressible peat and organic silt layers within the upper alluvium, as well as the presence of potentially liquefiable soils, we recommend that the buildings be supported on deep foundations consisting of augercast piles. Specific design and construction recommendations for augercast piles are presented in the following sections. 5.2.1. Augercast Piles Augercast piles are constructed using a continuous-flight, hollow-stem auger attached to a set of leads supported by a crane or installed with a fixed-mast drill rig. The first step in the pile casing process consists of drilling the auger into the ground to the specified tip elevation of the pile. Grout is then pumped through the hollow-stem during steady withdrawal of the auger, replacing the soils on the flights of the auger. The final step is to install a steel reinforcing cage and typically a center bar into the column of fresh grout. One benefit of using augercast piles is that the auger provides support for the soils during the pile installation process, thus eliminating the need for temporary casing or drilling fluid. 5.2.1.1. Construction Considerations The augercast piles should be installed using a continuous-flight, hollow-stem auger. As is standard practice, the pile grout must be pumped under pressure through the hollow stem as the auger is withdrawn. Maintenance of adequate grout pressure at the auger tip is critical to reduce the potential for encroachment of adjacent native soils into the grout column. The rate of withdrawal of the auger must remain constant throughout the installation of the piles to reduce the potential for necking of the piles. Failure to maintain a constant rate of withdrawal of the auger should result in immediate rejection of that pile. Reinforcing steel for bending and uplift should be placed in the fresh grout column as soon as possible after withdrawal of the auger. Centering devices should be used to provide concrete cover around the reinforcing steel. The contractor should adhere to a waiting period of at least 12 hours between the installation of piles spaced closer than 8 feet, center-to-center. This waiting period is necessary to avoid disturbing the curing concrete in previously cast piles. Grout pumps must be fitted with a volume-measuring device and pressure gauge so that the volume of the grout placed in each pile and the pressure head maintained during pumping can be observed. A minimum grout line pressure of 100 pounds per square inch (psi) should be maintained. The rate of auger withdrawal should be controlled during grouting such that the volume of the grout pumped is equal to at least 115 percent of the theoretical pile volume. A minimum head of 10 feet of grout should be maintained above the auger tip during withdrawal of the auger to maintain a full column of grout and to prevent hole collapse. The geotechnical engineer of record should observe drilling operations, monitor grout injection procedures, record the volume of grout placed in each pile relative to the calculated volume of the hole and evaluate the adequacy of individual pile installations. March 10, 2022 | Page 7 File No. 24939-001-00 5.2.1.2. Axial Capacity Axial pile load capacity in compression is developed from end bearing in the lower alluvial deposits and from side frictional resistance along the length of the pile. Uplift pile capacity will also be developed from side frictional resistance along the length of the pile. The depth to the competent lower alluvial soils varies below the proposed buildings, generally increasing in depth from east to west across the site. We recommend that pile lengths be determined based on the minimum required embedment depth in the lower alluvium to achieve the required pile capacity. On the west side of the site, where the lower alluvium is deeper, the piles will be longer and will consequently develop more side friction resistance in the thicker deposits of upper alluvium below the peat deposits. The allowable seismic capacities include the effects of downdrag and the residual strength of potentially liquefiable layers within the fill and upper alluvial deposits located below the groundwater table. For planning purposes, we recommend that the site be split into east and west areas. For this preliminary design purposes, the east and west areas are represented by the areas of the site that are east and west of the Cross Section A-A’ location (see Figure 4). Augercast pile capacities were developed based on embedment depths below the lower alluvium contact at Elevation -10 feet for the east area and Elevation -20 feet for the west area. Axial pile capacities are presented in Tables 2 and 3, for 18- and 24-inch-diameter augercast piles having 10 and 20 feet of embedment into the lower alluvial deposits. The bearing surface elevation contours for the lower alluvium is presented in Figure 3. Pile capacities for embedment depths between 10 and 20 feet can be linearly interpolated between the capacities presented in Tables 2 and 3. TABLE 2. ALLOWABLE AXIAL PILE CAPACITY – 18-INCH AUGERCAST PILES Location Lower Alluvium Elevation (feet) Embedment Depth/Minimum Pile Tip Elevation (feet) Static Capacity (kips) Seismic Capacity (kips) Downward Uplift Downward Uplift East -10 10 ft (El -20 ft) 105 130 270 100 East -10 20 ft (El -30 ft) 190 190 420 200 West -20 10 ft (El -30 ft) 170 175 315 115 West -20 20 ft (El -40 ft) 260 245 480 240 TABLE 3. ALLOWABLE AXIAL PILE CAPACITY – 24-INCH AUGERCAST PILES Location Lower Alluvium Elevation (feet) Embedment Depth/Minimum Pile Tip Elevation (feet) Static Capacity (kips) Seismic Capacity (kips) Downward Uplift Downward Uplift East -10 10 ft (El -20 ft) 195 175 455 130 East -10 20 ft (El -30 ft) 315 250 675 275 West -20 10 ft (El -30 ft) 290 235 530 155 West -20 20 ft (El -40 ft) 420 325 770 320 March 10, 2022 | Page 8 File No. 24939-001-00 Allowable pile capacities were evaluated based on Allowable Stress Design (ASD) and are for combined dead plus long-term live loads. The allowable capacities are based on the strength of the supporting soils and include a factor of safety of 2 for end bearing and side friction and a factor of safety of 1.1 for seismic conditions. The capacities apply to single piles. If piles are spaced at least three pile diameters on center, as recommended, no reduction of axial capacity for group action is needed, in our opinion. The structural characteristics of pile materials and structural connections may impose limitations on pile capacities and should be evaluated by the structural engineer. For example, steel reinforcing will be needed for augercast piles subjected to uplift or large bending moments. 5.2.1.3. Lateral Capacity Lateral loads can be resisted by passive soil pressures on the vertical piles and by the passive soil pressures on the pile cap. Because of the potential separation between the pile-supported foundation components and the underlying soil from settlement, base friction along the bottom of the pile cap should not be included in the calculations for lateral capacity. Table 4 summarizes the design parameters for laterally loaded piles. We recommend that these parameters be incorporated into the commercial software LPILE to evaluate response and capacity of piles subject to lateral loading. For potentially liquefiable soils, a reduced p-multiplier should be applied to the model P-Y curve of the relevant soil units for evaluating seismic conditions (Boulanger, et al. 2003). TABLE 4. LPILE SOIL PARAMETERS Soil Unit1 Approximate Depth Below Existing Grade (feet) Effective Unit Weight (pcf) Friction Angle (degrees) Stiffness Parameter, k (pci) P- Multiplier1 Top of Soil Layer Bottom of Soil Layer Fill (Above Groundwater Table) 0 9 120 34 110 Fill (Below Groundwater Table) 4 9 57.6 34 70 Upper Loose/Soft to Medium Dense/Medium Stiff Alluvium 9 63 57.6 31 50 1 (static) 0.1 (seismic) Lower Dense to Very Dense/Hard Alluvium 63 200 67.6 38 120 1 (static) 0.1 (seismic) Notes: 1 Sand (Reese) Model pcf – pounds per cubic foot pci – pounds per cubic inch Piles spaced closer than five pile diameters apart will experience group effects that will result in a lower lateral load capacity for trailing rows of piles with respect to leading rows of piles for an equivalent deflection. We recommend that the lateral load capacity for piles in a pile group spaced less than five pile diameters apart be reduced in accordance with the factors in Table 5 per AASHTO Load and Resistance Factor Design (LRFD) Bridge Design Specifications Section 10.7.2.4. March 10, 2022 | Page 9 File No. 24939-001-00 TABLE 5. PILE P-MULTIPLIERS, PM, FOR MULTIPLE ROW SHADING Pile Spacing1 (in terms of pile diameter) P-Multipliers, Pm2, 3 Row 1 (leading row) Row 2 (1st trailing row) Row 3 and higher (2nd trailing row) 3D 0.80 0.40 0.30 5D 1.00 0.85 0.70 Notes: 1. The P-multipliers in the table above are a function of the center to center spacing of piles in the group in the direction of loading expressed in multiples of the pile diameter, D. 2. The values of Pm were developed for vertical piles only per 2017 ASHTO LRFD Table 10.7.4-1. 3. The P-multipliers are dependent on the pile spacing and the row number in the direction of the loading to establish values of Pm for other pile spacing values, interpolation between values should be conducted. We recommend that the passive soil pressure acting on the pile cap be estimated using an equivalent fluid density of 350 pounds per cubic foot (pcf) where the soil adjacent to the foundation consists of adequately compacted structural fill. The passive resistance value includes a factor of safety of 1.5 and assumes a minimum lateral deflection of 1 inch to fully develop the passive resistance. Deflections that are less than 1 inch will not fully mobilize the passive resistance in the soil. 5.2.1.4. Pile Settlement We estimate that the post-construction settlement of pile foundations, designed and installed as recommended, will be on the order of 1 inch or less. Maximum differential settlement should be less than about one-half the post construction settlement. Most of this settlement will occur rapidly as loads are applied. 5.3. Footing Drains We recommend that perimeter footing drains be installed around each building. The perimeter drains should be installed at the base of the exterior footings as shown on Figure 7. The perimeter drains should be provided with cleanouts and should consist of at least 4-inch-diameter perforated pipe placed on a 3-inch bed of, and surrounded by, 6 inches of drainage material enclosed in a non-woven geotextile fabric such as Mirafi 140N (or approved equivalent) to prevent fine soil from migrating into the drain material. We recommend against using flexible tubing for footing drainpipes. The perimeter drains should be sloped to drain by gravity, if practicable, to a suitable discharge point, preferably a storm drain. We recommend that the cleanouts be covered and be placed in flush mounted utility boxes. Water collected in roof downspout lines must not be routed to the footing drain lines. 5.4. Floor Slabs Given that augercast piles is the recommended foundation support option, we recommend that the floor slabs be structurally supported on piles because of the estimated total and differential settlement under static and seismic loading. Since the slab will be pile-supported, the slab subgrade will only need to be prepared in a manner to facilitate construction and no specific requirements for soft soil removal and/or compaction below the lower level slabs are required. However, we recommend that concrete slabs-on-grade be constructed on a gravel layer to provide uniform support and drainage, and to act as a capillary break as shown in Figure 7. March 10, 2022 | Page 10 File No. 24939-001-00 5.4.1. Design Features We recommend that the floor slabs be underlain by a capillary break gravel layer consisting of at least 6 inches of clean crushed gravel meeting the requirements of Section 9-03.1(4)C, Grading No. 67 of the 2020 Washington State Department of Transportation (WSDOT) Standard Specifications. The gravel layer should be placed directly over the prepared subgrade. If water vapor migration through the slabs is objectionable, the gravel should be covered with a heavy plastic sheet, such as 10-mil plastic sheeting, to act as a vapor retarder. This will be necessary in occupied spaces and where the slabs will be surfaced with tile or will be carpeted. It may also be prudent to apply a sealer to the slab to further retard the migration of moisture through the floor. The contractor should be made responsible for maintaining the integrity of the vapor retarder during construction. 5.5. Methane Collection Provisions should be made under the floor slab to vent potential accumulations of methane gas generated by decomposition of the peat and other underlying organic soils. We recommend placing a perforated pipe within a gravel layer and venting the pipes outside the building. Methane vapor mitigation should also include placing a 30-mil polyvinyl chloride (PVC) geomembrane beneath the floor slab to act as a methane and water vapor barrier. 5.5.1. Methane Barrier We recommend that the methane barrier consist of a 30-mil PVC geomembrane liner. The geomembrane should be installed by an approved and experienced contractor. All seams and penetrations must be sealed/welded in accordance with the manufacturer’s recommendations. All tears or punctures must be repaired in accordance with the manufacturers’ requirements. Equipment traffic and foot traffic on top of the installed barrier must be kept to a minimum. A cushion geotextile may also be used to protect the barrier from necessary traffic. Also, the contractor must not drive any form stakes through the barrier or otherwise damage the barrier during construction. The geomembrane should be installed in such a manner as to provide an impermeable seal at all pipe penetrations or discontinuities, such as interior and exterior foundations, grade beams, column risers and utility pipes which penetrate the barrier. On subgrade surfaces, all sharp points and projections must be removed to limit rips, tears, and punctures of the geomembrane. If damage is identified during geomembrane installation, it must be repaired immediately. The geomembrane installation must be constructed in accordance with the manufacturer’s recommendations. Geomembrane integrity testing should also be completed in accordance with the manufacturer/installer approved quality assurance manual. Where punctures, tears and/or unsatisfactory welded seams are identified, appropriate repairs should be made until no evidence of potential leaks are detected. These repairs should be documented and approved by the owner’s representative. The engineer should observe the installer’s QA/QC program during construction. March 10, 2022 | Page 11 File No. 24939-001-00 5.5.2. Vent Pipe System For planning purposes, we recommend a perforated vent pipe be installed within 10 feet of the inner perimeter of the building footprints. The perforated pipes should be placed within a 6-inch layer of clean crushed gravel with negligible sand or silt in conformance with Section 9-03.1(4)C, Grading No. 67 of the 2020 WSDOT Standard Specifications. The pipes should be backfilled as described in the “Underslab Utility Support” section. The perforated pipes should consist of 4-inch-diameter, machine slotted PVC pipe, or an approved equal. Solid wall (blank) PVC pipe should be used in below-grade pipe runs that extend outside the building footprint. The horizontal pipe runs should continue to vertical riser pipes placed beyond the exterior building walls to vent vapors to the atmosphere. The vertical riser pipe should be vented such that precipitation cannot enter the pipe, 5.6. Underslab Utility Support We recommend that the floor slab will be structurally supported, as described previously. To mitigate the potential for damage to utilities below the slab resulting from settlement of the underlying soils, we recommend that underslab utilities be structurally suspended from the slab. Pea gravel should be placed as backfill above the underslab utilities in order to reduce the soil loads acting on the suspended utilities. The pea gravel is anticipated to flow around the suspended utilities as settlement occurs. GeoEngineers can be consulted to provide estimates of loads acting on the suspended utilities once the details regarding the depth and size of utilities are known. Alternatively to backfilling with pea gravel, the underslab utilities can be installed without backfilling such that they are surrounded by a void space. Even with this alternative, the utilities need to structurally suspended from the slab. Flexible connections should be provided for all utilities that transition from the pile supported buildings to surrounding areas. Surrounding areas without a net grade increase should be expected to settle on the order of 8 to 12 inches over a design life of 50 years from secondary compression in peat and organic soils. 5.7. Hardscape and Utilities Concrete hardscape areas, such as entry slabs and sidewalks, and utilities on the outside of the buildings may experience long-term settlement after a design seismic event or as the organic soils compress. If finished grades are raised by more than about 1 to 2 feet relative to existing grades, long-term settlement due to consolidation settlement may also occur. Sidewalks along the building should be detached so that the side closest to the building does not hang up on the pile-supported structure and cause sidewalks to tilt. Entries should be designed as a ramp with one end supported on the building and the other end supported on the ground to avoid the development of abrupt changes in grade. Sidewalks and entry slabs should be underlain by a minimum 4-inch-thick layer of crushed surfacing base course (CSBC). March 10, 2022 | Page 12 File No. 24939-001-00 5.8. Earthwork Based on the subsurface conditions observed in the borings and CPTs, we expect that the soils at the site may be excavated using conventional heavy-duty construction equipment. Near surface site soils (fill material) generally consist of loose to medium dense sand and gravel with variable silt and medium stiff to very stiff silt. 5.8.1. Clearing and Site Preparation Construction of the proposed buildings and site improvements will require demolition of the existing Fry’s Electronics building and removal of the existing asphalt surface, walkways, concrete curbing, etc. Asphalt and concrete may be recycled and reused as structural fill in limited areas outside the building footprints; otherwise, it should be removed from the site along with other construction debris. The recycled concrete should be reused as described in the section of this report titled “Reuse of Existing Asphalt, Basecourse and Concrete Rubble.” All existing utilities should be removed from the building footprints and rerouted if needed. Areas to receive fill, structures, or pavements should be cleared of vegetation and stripped of topsoil, if any. Clearing should consist of removal of all debris, trees, brush and other vegetation within the designated clearing limits. The topsoil materials could be separated and stockpiled for use in areas to be landscaped. Debris should be removed from the site, but organic materials could be chipped/composted and also reused in landscape areas, if desired. We anticipate that the depth of stripping will range from 4 to 6 inches in landscape areas located on the site. Actual stripping depths should be determined based on field observations at the time of construction. The organic soils can be stockpiled and used later for landscaping purposes or may be spread over disturbed areas following completion of grading. Materials that cannot be used for landscaping or protection of disturbed areas should be removed from the project site. Grubbing should consist of removing and disposal of stumps, roots larger than 1-inch-diameter, and matted roots from the designated grubbing areas. Grubbed materials should be completely removed from the project site. All depressions made during the grubbing activities to remove stumps and other materials, should be completely backfilled with properly placed and compacted structural fill. GeoEngineers should evaluate the exposed soil after completion of stripping and grubbing is completed to confirm suitability prior to site development. Care must be taken to minimize softening of subgrade soils during stripping operations. Areas of the exposed subgrade which become disturbed should be compacted to a firm, non-yielding condition, if practical, prior to placing any structural fill necessary to achieve design grades. If this is not practical because the material is too wet, the disturbed material must be aerated and recompacted or excavated and replaced with structural fill. 5.8.2. Subgrade Preparation Prior to placing new fills and pavement or hardscape base course materials subgrade areas should be proof rolled to locate soft or pumping soils. Prior to proof rolling, unsuitable soils should be removed from below building and pavement/hardscape areas. Proof rolling can be completed using a piece of heavy tire- mounted equipment such as a loaded dump truck. During wet weather, the exposed subgrade areas should March 10, 2022 | Page 13 File No. 24939-001-00 be probed to determine the extent of soft soils. If soft or pumping soils are observed, they should be removed and replaced with structural fill. If deep pockets of soft silt or pumping soils are encountered outside the building footprints, it may be possible to limit the depth of overexcavation by placing a woven geotextile fabric such as Mirafi 600X (or similar material) on the overexcavated subgrade prior to placing structural fill. The geotextile will provide additional support by bridging over the soft material and will help reduce fines contamination into the structural fill. This may be performed under pavement areas depending on actual conditions observed during construction, but it is not necessary under the planned buildings. After completing the proof-rolling, the subgrade areas should be recompacted to a firm and unyielding condition, if possible. The achievable degree of compaction will depend on when construction is performed. If the work is performed during dry weather conditions, we recommend that all subgrade areas be recompacted to at least 95 percent of the MDD in accordance with the American Society for Testing and Materials (ASTM) D 1557 test procedure (modified proctor). If the work is performed during wet weather conditions, it may not be possible to recompact the subgrade to 95 percent of the MDD. In this case, we recommend that the subgrade be compacted to the extent possible without causing undue heaving or pumping of the subgrade soils. Subgrade disturbance or deterioration could occur if the subgrade is wet and cannot be dried. If the subgrade deteriorates during proof rolling or compaction, it may become necessary to modify the proof rolling or compaction criteria or methods. 5.8.3. Subgrade Protection Site soils may contain significant fines content (silt/clay) and will be highly sensitive and susceptible to moisture and equipment loads. The contractor should take necessary measures to prevent site subgrade soils from becoming disturbed or unstable and maintain as much of the existing pavement as practicable. Construction traffic during the wet season should be restricted to specific areas of the site, preferably areas that are surfaced with crushed rock materials or areas with existing pavement which are not susceptible to wet weather disturbance. 5.8.4. Structural Fill All fill, whether on-site soils or imported fill for support of foundations, floor slab areas, pavement areas and as backfill for retaining walls or in utility trenches should meet the criteria for structural fill presented below. Structural fill soils should be free of organic matter, debris, man-made contaminants, and other deleterious materials, with no individual particles larger than 4 inches in greatest dimension. The suitability of soil for use as structural fill depends on its gradation and moisture content. 5.8.4.1. Materials Recommended structural fill material quality varies depending upon its use as described below: ■ Structural fill to construct pavement areas, to place below floor slabs, to construct embankments, to backfill retaining walls and utility trenches, and to place against pile caps should consist of gravel borrow as described in Section 09-03.12(1) of the 2020 WSDOT Standard Specifications, with the additional restriction that the fines content be limited to no more than 5 percent, especially if the work occurs in wet weather or during the wet season (October through May). March 10, 2022 | Page 14 File No. 24939-001-00 ■ Structural fill placed around footing drains should consist of washed ⅜-inch to No. 8 pea gravel per Section 9-03.1(4)C Grading No. 8, or conform to Section 9-03.12(4) of the 2020 WSDOT Standard Specifications, as shown on Figure 7. ■ Structural fill placed as CSBC below pavements should conform to Section 9-03.9(3) of the 2020 WSDOT Standard Specifications. ■ Structural fill placed as capillary break below slabs should consist of 1-inch minus clean crushed gravel with negligible sand or silt in conformance with Section 9-03.1(4)C, Grading No. 67 of the 2020 WSDOT Standard Specifications, as shown on Figure 7. We recommend that the suitability of structural fill soil from proposed borrow sources be evaluated by a representative of our firm before the earthwork contractor begins transporting the soil to the site. 5.8.4.2. Reuse of On-site Soils The on-site fill is generally fine-grained and has natural moisture contents above typical optimum moisture content for these soil types, and it will be difficult to achieve the minimum compaction requirements without drying the soils significantly during the summer months. In our opinion, the on-site soils should not be planned for use as structural fill. The fine-grained upper alluvial soils (silt) are not suitable for reuse as structural fill and should be disposed of off-site. Imported gravel borrow should be used for structural fill and backfilling throughout the site. The on-site fill may be reused in landscape areas outside the building footprint; however, grading should be planned during the normally dry season (June through September). The contractor should plan to cover all fill stockpiles with plastic sheeting if it will be used as structural fill. The reuse of on-site soils is highly dependent on the skill of the contractor, schedule, and the weather, and we will work with the design team to maximize the reuse of on-site soils outside the building footprint. 5.8.4.3. Reuse of Existing Asphalt, Basecourse and Concrete Rubble Existing asphalt pavement and Portland cement concrete (PCC) rubble may be reused as structural fill if properly crushed during demolition. Recycled PCC rubble and base course materials may be reused as structural fill throughout the project, including under the building footprints. Recycled asphalt may be used under new pavement and in utility trenches but should not be used under foundations or below the buildings. Recycled asphalt and concrete should not be used in landscape areas. Location-specific restrictions on use of recycled materials may apply, therefore we recommend checking with local permit authorities before planning to use recycled materials. For use as general structural fill, the asphalt and concrete rubble should be crushed or otherwise ground up and should meet gradation requirements for gravel borrow as described in Section 9-03.14(1) of the 2020 WSDOT Standard Specifications. If recycled asphalt and/or concrete will be used under pavement areas, we recommend that it meet gradation requirements for CSBC as described in Section 9-03.9(3) of the 2020 WSDOT Standard Specifications. 5.8.4.4. Fill Placement and Compaction Criteria Structural fill should be mechanically compacted to a firm, non-yielding condition. Structural fill should be placed in loose lifts not exceeding 12 inches in thickness when using heavy compaction equipment and not more than 6 inches when using hand operated compaction equipment. The actual thickness will be dependent on the structural fill material used and the type and size of compaction equipment. Each lift should be moisture conditioned to within about 2 percent of the optimum moisture content and compacted March 10, 2022 | Page 15 File No. 24939-001-00 to the specified density before placing subsequent lifts. Compaction of all structural fill should be in accordance with the ASTM D 1557 test method. Structural fill should be compacted to the following criteria: ■ Structural fill in new pavement and hardscape areas outside the City right of way including utility trench backfill, should be compacted to at least 90 percent of the MDD, except that the upper 2 feet of fill below final subgrade should be compacted to at least 95 percent of the MDD, as shown in Figure 8. ■ Structural fill placed within the City right of way, including fill for mass grading and utility trench backfill, should be compacted to at least 95 percent of the MDD or as required by the City. ■ Structural fill placed below floor slabs should be compacted to at least 95 percent of the MDD, including backfill for utility trenches below the building footprint. ■ Structural fill placed as crushed rock base course below pavements and hardscape should be compacted to at least 95 percent of the MDD. ■ Non-structural fill, such as fill placed in landscape areas, should be compacted to at least 90 percent of the MDD, unless otherwise specified by the landscape architect. 5.8.4.5. Weather Considerations Disturbance of near surface soils should be expected if earthwork is completed during periods of wet weather. During dry weather, the soils will: (1) be less susceptible to disturbance, (2) provide better support for construction equipment, and (3) be more likely to meet the required compaction and subgrade preparation criteria. The wet weather season generally begins in October and continues through May in western Washington; however, periods of wet weather may occur during any month of the year. For earthwork activities during wet weather, we recommend that the following steps be taken: ■ The ground surface in and around the work area should be sloped so that surface water is directed away from the work area. The ground surface should be graded so 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, and it should not be directed towards downslope structures, unless properly collected and conveyed to appropriate catch basins. ■ Earthwork activities should not take place during periods of moderate to 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 temporary construction dewatering, the use of plastic sheeting, sumps with pumps, and grading. 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. ■ The contractor should cover all soil stockpiles that will be used as structural fill with plastic sheeting. ■ Construction traffic should be restricted to specific areas of the site, preferably areas that are surfaced with working pad materials not susceptible to wet weather disturbance. March 10, 2022 | Page 16 File No. 24939-001-00 ■ Construction activities should be scheduled so that the length of time that soils are left exposed to moisture is reduced to the extent practical. Routing of equipment on the existing fill during the wet weather months will be difficult and the subgrade will likely become highly disturbed and rutted. In addition, a significant amount of mud can be produced by routing equipment directly on the on-site soils in wet weather. Therefore, to protect the subgrade soils and to provide an adequate wet weather working surface for the contractor’s equipment and labor, we recommend that the contractor protect exposed subgrade soils with a crushed gravel working pad at least 12 inches thick underlain by a geotextile separator where needed. 5.8.5. Temporary Cut Slopes For planning purposes, temporary unsupported cut slopes more than 4 feet high may be inclined 1½H:1V (horizontal to vertical) in the fill and upper alluvial soils. This temporary cut slope inclination may need to be flattened by the contractor if significant caving/sloughing or groundwater seepage occurs. For open cuts at the site, we recommend that: ■ No traffic, construction equipment, stockpiles, or building supplies be allowed at the top of the cut slopes within a distance of at least 5 feet from the top of the cut; ■ The excavation does not encroach on a 1H:1V influence line projected down from the edges of nearby or planned foundation elements; ■ Exposed soil along the slope be protected from surface erosion using waterproof tarps or plastic sheeting or flash coating with shotcrete; ■ Construction activities be scheduled so the length of time the temporary cut is left open is reduced to the extent practicable; ■ Erosion control measures be implemented as appropriate such that runoff from the site is reduced to the extent practicable; ■ Surface water be diverted away from the excavation; and ■ The general condition of the slopes be observed periodically by GeoEngineers to confirm adequate stability. Because the contractor has control of the construction operations, the contractor should be made responsible for the stability of the cut slopes, as well as the safety of the excavations. Temporary slopes must conform to applicable local, state and federal safety regulations. 5.8.6. Erosion and Sediment Control Construction activities including stripping and grading will expose soils to the erosional effects of wind and water. The amount and potential impacts of erosion are partly related to the time of year that construction actually occurs. Wet weather construction will increase the amount and extent of erosion and potential sedimentation. We recommend maintaining existing vegetation during the wet season, if possible, to reduce potential erosion. Erosion and sedimentation control measures may be implemented by using a combination of interceptor swales, straw bale barriers, silt fences and straw mulch for temporary erosion protection of exposed soils. March 10, 2022 | Page 17 File No. 24939-001-00 All disturbed areas should be finished graded and paved or landscaped as soon as practicable to reduce the risk of erosion. 5.8.7. Utility Trenches Trench excavation, pipe bedding and trench backfilling should be completed using the general procedures described in the 2020 WSDOT Standard Specifications, or City of Renton requirements, or as specified by the project civil engineer. Utility trench backfill should consist of structural fill and should be placed in lifts of 12 inches or less (loose thickness) when using heavy compaction equipment, and 6 inches or less when using hand compaction equipment, such that adequate compaction can be achieved through the lift. Each lift must be compacted prior to placing the subsequent lift. Prior to compaction, the backfill should be moisture conditioned to within 2 percent of the optimum moisture content. The backfill should be compacted in accordance with the criteria discussed above. General utility trench backfill recommendations are provided in Figure 8. 5.9. Pavement Recommendations 5.9.1. Subgrade Preparation We recommend the subgrade soils in new pavement areas be prepared and evaluated as described in the “Subgrade Preparation” section of this report. All new pavement and hardscape areas should be supported on subgrade soils that have been proof rolled or probed, and approved by the geotechnical engineer. If the exposed subgrade soils are loose or soft, it may be necessary to excavate localized areas and replace them with structural fill or gravel base course. Pavement subgrade conditions should be observed during construction and prior to placing the base course materials in order to evaluate the presence of zones of unsuitable subgrade soils and the need for over-excavation and replacement of these zones. 5.9.2. New Hot Mix Asphalt Pavement In light-duty pavement areas (e.g., automobile parking), we recommend a pavement section consisting of at least a 3-inch thickness of ½-inch hot-mix asphalt (HMA) per WSDOT Sections 5-04 and 9-03, over a 4-inch thickness of densely compacted CSBC per WSDOT Section 9-03.9(3). In heavy-duty pavement areas (such as driveways, truck traffic lanes, materials delivery), we recommend a pavement section consisting of at least a 4-inch thickness of ½-inch HMA over a 6-inch thickness of densely compacted CSBC. The base course should be compacted to at least 95 percent of the MDD obtained using ASTM D 1557. We recommend that proof rolling of the subgrade and compacted base course be observed by a representative from our firm prior to paving. Soft or yielding zones observed during proof rolling may require overexcavation and replacement with compacted structural fill. The pavement sections recommended above are based on our experience. Thicker asphalt sections may be needed based on the City of Renton requirements, or actual traffic data, truck loads, and intended use. All paved and landscaped areas should be graded so that surface drainage is directed to appropriate catch basins. 5.9.3. Portland Cement Concrete Pavement PCC sections may be considered for areas where concentrated heavy loads may occur. We recommend that these pavements consist of at least 6 inches of PCC over 6 inches of CSBC over a 12-inch-thick March 10, 2022 | Page 18 File No. 24939-001-00 subbase. A thicker concrete section may be needed based on the actual load data for use of the area. If the concrete pavement will have doweled joints, we recommend that the concrete thickness be increased by an amount equal to the diameter of the dowels. The base and subbase layers should be compacted to at least 95 percent of the MDD. The subbase layer may consist of imported gravel borrow. We recommend PCC pavements incorporate construction joints and/or crack control joints spaced at maximum distances of 12 feet apart, center-to-center, in both the longitudinal and transverse directions. Crack control joints may be created by placing an insert or groove into the fresh concrete surface during finishing, or by saw cutting the concrete after it has initially set-up. We recommend the depth of the crack control joints be approximately one fourth the thickness of the concrete; or about 1½ inches deep for the recommended concrete thickness of 6 inches. We also recommend the crack control joints be sealed with an appropriate sealant to help restrict water infiltration into the joints. 5.9.4. Asphalt-Treated Base If pavements are constructed during the wet seasons, consideration may be given to covering the areas to be paved with asphalt-treated base (ATB) for protection. Light-duty pavement areas should be surfaced with 3 inches of ATB, and heavy-duty pavement areas should be surfaced with 6 inches of ATB. ATB placed to support construction equipment and heavy construction loads should also be at least 6 inches thick, but should be evaluated by the contractor if thicker sections are needed. Prior to placement of the final pavement sections, we recommend the ATB surface be evaluated and areas of ATB pavement failure be removed, and the subgrade repaired. If ATB is used and is serviceable when final pavements are constructed, the CSBC can be eliminated, and the design PCC or asphalt concrete pavement thickness can be placed directly over the ATB. 5.10. Construction Dewatering Static groundwater was observed ranging from about 7½ to 10 feet below existing grades at the site. Therefore, excavations for utility trenches, underground vaults and elevation shafts may encounter groundwater. Dewatering during construction of these areas and other excavations on site may be required. Based on the soil conditions and our experience in the area, we expect that groundwater in excavations less than about 7 feet below existing site grades can be controlled by open pumping using sump pumps. For excavations extending deeper and below the static groundwater table, dewatering using well points or deep wells will be necessary. We recommend that the contractor be required to submit a proposed dewatering system design and plan layout to the project team for review and comment prior to beginning construction. The level of effort for dewatering will depend on the time of year during which construction is accomplished. Less seepage into the work areas and a lower water table should be expected if construction is accomplished in the late summer or early fall months, and correspondingly, more seepage and a higher water table should be expected during the wetter periods of the year and into spring months. We recommend that earthwork activities be completed in the late summer or early fall months when precipitation is typically at its lowest. March 10, 2022 | Page 19 File No. 24939-001-00 5.11. Infiltration Considerations Groundwater is located about 7½ to 10 feet below existing grades. Fill exists across the site, but generally at or above the groundwater level. Fill is susceptible to settlement due to stormwater infiltration. The percent fines in the soil above the groundwater table ranges from 31 to 80 percent. We anticipate that the design infiltration will be low, about ½-inch per hour or less. If infiltration facilities are planned for the site, pilot infiltration tests will be required at the proposed locations of the infiltration facilities. In addition, an evaluation will be needed to assess dewatering induced settlement and mounding effects in the fill. 6.0 RECOMMENDED ADDITIONAL GEOTECHNICAL SERVICES Throughout this report, recommendations are provided where we consider additional geotechnical services to be appropriate. These additional services are summarized below: ■ 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 stripping and grading; observe and evaluate installation of augercast piles; observe and evaluate the suitability of foundations, wall and floor slab subgrades; observe removal of unsuitable fill and debris/rubble from below the building footprints and hardscape areas; observe and test structural fill including wall and utility trench backfill; observe installation of subsurface drainage measures; evaluate suitability of pavement subgrades and other appurtenant structures, and provide a summary letter of our construction observation services. The purpose of GeoEngineers’ construction phase services is to confirm that the subsurface conditions revealed during the work differ from those anticipated, to evaluate whether or not earthwork and foundation installation activities are completed in accordance with our recommendations, and other reasons as described in Appendix D, Report Limitations and Guidelines for Use. 7.0 LIMITATIONS We have prepared this report for the exclusive use of Bay West Development Holdings, LLC and their authorized agents for the 800 Garden Mixed-Use Development project 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/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 D for additional information pertaining to use of this report. March 10, 2022 | Page 20 File No. 24939-001-00 8.0 REFERENCES D. R. Mullineaux, 1965. “Geologic Map of the Renton Quadrangle, King County, Washington.” National Geologic Map Database. U.S. Geological Survey (USGS). Yount, James C., Minard, James P., and Dembroff, Glenn R., 1993. “Geologic Map of Surficial Deposits in the Seattle 30’ x 60’ Quadrangle, Washington.” National Geologic Map Database. U.S. Geological Survey (USGS). ASCE 7-10, 2010. “Minimum Design Loads for Buildings and Other Structures,” American Society of Civil Engineers. ASTM D-1557, 2012. “Standard Testing Method for Laboratory Compaction Characteristics of Soil Using Modified Effort,” ASTM International. GeoEngineers, Inc., 2006. “Geotechnical Engineering Services Lowe’s of Renton Site, Renton, Washington.” GeoEngineers’ File No. 8335-003-00. Kleinfelder, 2001 “Geotechnical Investigation Report Proposed Fry’s Electronics Superstore No. 30, 900 Garden Avenue North, Renton, WA.” Naval Facilities Engineering Command, 1986. “Foundations & Earth Structures.” Idriss, I.M. and Boulanger, R.W., 2014. “CPT and SPT Based Liquefaction Triggering Procedures.” International Code Council, 2018. “International Building Code.” Idriss, I. M., and R. W. Boulanger, 2008. “Soil Liquefaction during Earthquakes.” Earthquake Engineering Research Institute MNO-12. USGS Unified Hazard Tool (Version Dynamic: Conterminous U.S. 2014 (update) (v4.2.0)). Ishihara, K., and Yoshimine M., “Evaluation of Settlements in Sand Deposits Following Liquefaction During Earthquakes,” Soils and Foundations, 32(1), 1992, pp. 1773-188. Tokimatsu K., Seed H.B. 1987. “Evaluation of settlements in sands due to earthquake shaking,” Journal of Geotechnical Engineering, 1987, vol. 113, pp. 861-878. Youd, T. L. and Idriss, I. M. 2001. “Liquefaction Resistance of Soils: Summary Report from the 1996 NCEER and 1998 NCEER/NSF Workshops on Evaluation of Liquefaction Resistance of Soils,” Journal of Geotechnical and Geoenvironmental Engineering, Vol. 127, No. 4, April 2001, pp. 298-313 Washington State Department of Transportation, 2020. “Standard Specifications for Road, Bridge and Municipal Construction.” FIGURES n Ave NE NE 1 2 t h S t NE 1 6 t h S t 900 Gene Coulon Memorial Beach Park B urlingtonNorthern Santa FeN 6th St N 6 t h StGarden AveNN 4 t h S t Houser Way BypN 8th St N 10th S t N L a n d i n g W a y N 1 0t h Pl N 5 th S t Williams Ave NBurnettAveNN 6 t h S t Park Ave NLoganAve NSouthport Dr N 900 900 900 405 The Landing NE 1 2 t h S t NE 16th S t N E 16th SndsAve NEEdmonds Ave NE NE 1 0 t h S t NE 9 t h St NE 5 t h P l NE 6t h P l900 Windsor Hills Park SITE Vicinity Map Figure 1 800 Garden Development Renton, Washington 3 Alpine Lakes Wilderness Kent Tacoma Seattle 1,000 1,0000 Feet Data Source: ESRI. World Navigation Map. Notes: 1. The locations of all features shown are approximate.2. This drawing is for information purposes. It is intended to assist inshowing features discussed in an attached document. GeoEngineers, Inc.cannot guarantee the accuracy and content of electronic files. The masterfile is stored by GeoEngineers, Inc. and will serve as the official record ofthis communication. Projection: NAD 1983 UTM Zone 10N P:\24\24939001\GIS\24939001_Project\24939001_Project.aprx\2493900100_F01_VicinityMap Date Exported: 01/27/21 by ccabrera STOPGGGSTOPSTOP STOP STOPSTOPSTOP STOP NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE GSTOPSTOP STOPNO PARKING F IRE LANENO PARK ING FIRE LANENO PARKING FIRE LANESTOPCP #1CP # 2 CP #3CP #4CP #5 CP #6 CP #7CP #8CP #9CP #1030'30'30'30'30'30'C1C2 C3 C4C5 L3C2 30 30 30303131 31 31 32 33 31 31 323333 31 32 34 3335 3334 333432 33 34 34 34 3534 3333 343535 33 34 3434 3435 3434 353433 3334 34 3534353435353634353633333435 3635363637 3637 3838 3534 363738 3738 3534 34 3536 34 34 34 3 434343536 363535 3435 34 36 37 353535 353433 34 34 35 34 34 36 35 34 34 36 35353 637 35 34 34 36 36 3534 353535 343331 32 3 2 32 32 33 3435 32 33 34 34 33353637353531 363 3 34 34 323432 33 34 34 32 8-STORY MIXED USE-PHASE 1 7-STORY MIXED USE-PHASE 2 7-STORY MIXED USE-PHASE 3 N 10th StGarden Ave NPrivate DriveFry's ElectronicsN 8th StA'A B'BC'CB-1 B-2 B-3 B-4 CPT-1 CPT-2 CPT-3 CPT-4 CPT-5 CPT-6 CPT-7 CPT-8 B-3 B-7 B-6 B-14 B-13 B-15 B-11 B-10 B-5 B-7 B-9 B-8 B-6 B-4 B-1 B-2 B-3 B-18 B-19 B-20 B-16 B-17 B-12 Figure 2 800 Garden Development Renton, Washington Site Plan \\geoengineers.com\WAN\Projects\24\24939001\CAD\00\Geotech\2493900100_F02_Site Plan.dwg TAB:F02 Date Exported: 03/09/22 - 15:14 by mwoodsProposed Layout WENSNotes: 1. The locations of all features shown are approximate. 2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. GeoEngineers, Inc. cannot guarantee the accuracy and content of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication. Data Source: Topographic Survey from kpff dated 12/21/2020. Projection: NAD83 Washington State Planes, North Zone, US Foot Feet 0 Legend 100 100 Boring by GeoEngineers, Inc., 2006B-3 Boring by GeoEngineers, Inc., 2021B-1 CPT-1 Cone Penetrometer Test by GeoEngineers, Inc., 2021 Boring by Kleinfelder, 2001B-1 Cross Section LocationA A' STOPGGGSTOPSTOP STOP STOPSTOPSTOP STOP NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE GSTOPSTOP STOPNO PARKING F IRE LANENO PARK ING FIRE LANENO PARKING FIRE LANESTOPCP #1CP #2CP #3CP # 4 CP # 5 CP #6CP #7 CP # 8CP #9 CP #10 30'30'30'30'30'30'C1C2 C3 C4 C5 L3C2 30 30 30303131 31 31 32 33 31 31 323333 31 32 34 3335 3334 333432 33 34 3 4 34 3534 3333 343535 33 34 3434 3435 3434 353433 3334 34 3534353435353634353633333435 3635363637 3637 3838 3534 363738 3738 3534 34 3536 34 34 34 3434343536 363535 3435 34 36 37 353535 353433 34 34 35 34 34 36 35 34 34 36 35353 637 35 34 34 36 36 3534 353535 343331 32 3 2 32 32 33 3435 32 33 34 34 33353637353531 363 3 34 3 4 323432 33 3434 32 N 8th StGarden Ave NPrivate DriveFry's ElectronicsN 10th St-20 -10 -26 -24 -22 -18 -16 -14 -12 -10 -18 -16 -14 -12 -8 -30 -20 -10 -34 -32 -28 -26 -24 -22 -18 -16 -14 -12 -8 -6 -4 -30 -32 8-STORY MIXED USE-PHASE 1 7-STORY MIXED USE-PHASE 2 7-STORY MIXED USE-PHASE 3 A'A B'BC'CB-1 -21.00 B-2 -11.00 B-3 -31.00 B-4 -25.00 CPT-1 -31.00 CPT-2 -3.00 CPT-3 -10.00 CPT-4 -7.00 CPT-5 CPT-6 CPT-7 -5.00 CPT-8 -36.00 B-15 B-11 B-10 B-5 -16.00 B-7 -30.00 B-9 -6.00 B-8 -18.00 B-6 -21.00 B-4 -27.00 B-1 -28.00 B-2 B-3 B-18 B-19 B-20 B-16 B-17 -30 -20 -28 -26 -24 -22 Figure 3 800 Garden Development Renton, Washington Bearing Soils Contour Map \\geoengineers.com\WAN\Projects\24\24939001\CAD\00\Geotech\2493900100_F03_Bearing Contours Elevation Map.dwg TAB:F03 Date Exported: 03/09/22 - 15:14 by mwoodsWENSFeet 0100 100 Legend Boring by GeoEngineers, Inc., 2006B-3 Boring by GeoEngineers, Inc., 2021B-1 CPT-1 Cone Penetrometer Test by GeoEngineers, Inc., 2021 Boring by Kleinfelder, 2001B-1 Cross Section LocationA A' Notes: 1. The locations of all features shown are approximate. 2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. GeoEngineers, Inc. cannot guarantee the accuracy and content of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication. Data Source: Topographic Survey from kpff dated 12/21/2020. Projection: NAD83 Washington State Planes, North Zone, US Foot Bearing Soils Contour-26 Elevation (Feet)Elevation (Feet)Distance (Feet) -60 -40 -20 0 20 40 60 -60 -40 -20 0 20 40 60 0 100 200 300 400 500 600 700 800 900 1000 1050 Existing BuildingExisting Grade A (North) A' (South) 7-Story Mixed Use Phase 1 7-Story Mixed Use Phase 2 7-Story Mixed Use Phase 3 B-1(11 ft)B-4(65 ft)CPT-7(20 ft)B-5(30 ft)B-2 (Kleinfelder)(9 ft)B-19(9 ft)B-16(9 ft)B-2(72 ft)B-8 (Kleinfelder)(1 ft)30'B-10 (Kleinfelder)(38 ft)40' QT (tsf) 0 500 26 15 5 ML/SM SM PT 50/5"* 28 18 5 3 3 4 4 6 38 7 12 28 40 50 56 60 GP-GM SM ML PT SM OH PT SM CL ML SM SP-SM 35 18 3 GP ML/SM SP PT OL 17 22 17 4 6 4 5 19 26 5 45 34 34 43 42 36 38 GPSMML ML PT SM PT SP-SM SM CL SP-SM 19 7 12 SMGP SM/ML SANDPTOL SP 31 18 5 6 GP SM/ML PT 4 45 16 26 42 52 29 SM SP 17 12 4 GP SM/ML PT SP SP SP 20 12 39 35 10 15 17 48 OL SP SP 34 18 6 20 GP SM SM/ML PT SP GP 34 20 11 4 SP SP PL PT 9 8 17 44 SP OL/PT CL SP 36 41 23 23 7 5 3 26 24 38 12 12 19 13 17 45 44 78 40 GP-GM ML ML PT SM SP-SM PT ML CL SM SP-SM ML 15 3 12 GP SM SM/ML PT SP 24 28 Fill Upper Alluvium Lower Alluvium Figure 4 Cross Section A-A'\\geoengineers.com\WAN\Projects\24\24939001\CAD\00\Geotech\2493900100_F04-6_Cross Sections.dwg TAB:F04 Date Exported: 03/02/22 - 16:05 by mwoods800 Garden Development Renton, Washington Legend Notes: 1. The subsurface conditions shown are based on interpolation between widely spaced explorations and should be considered approximate; actual subsurface conditions may vary from those shown. 2. This figure is for informational purposes only. It is intended to assist in the identification of features discussed in a related document. Data were compiled from sources as listed in this figure. The data sources do not guarantee these data are accurate or complete. There may have been updates to the data since the publication of this figure. This figure is a copy of a master document. The hard copy is stored by GeoEngineers, Inc. and will serve as the official document of record. Datum: NAVD 88, unless otherwise noted. Groundwater observed Legend SM 20 Boring Soil Classification Blow CountBoring ID(Offset)Inferred Soil Contact QT (tsf) 0 500 Cone Penetration Test Tip Resistance Horizontal Scale in Feet 0100 100 Vertical Scale in Feet 020 20 Vertical Exaggeration: 5X Fill Upper Alluvium Lower AlluviumCPT ID(Offset) Elevation (Feet)Elevation (Feet)Distance (Feet) -70 -60 -40 -20 0 20 40 -70 -60 -40 -20 0 20 40 0 50 100 150 200 250 300 350 400 440 Existing Grade B (West) B' (East)B-2(60 ft)CPT-3(33 ft)B-18(45 ft)B-19 (Kleinfelder)(38 ft)B-20 (Kleinfelder)(38 ft)QT (tsf) 0 500 QT (tsf) 0 500 19 6 3 ML/SM GP PTML 35 18 3 GP ML/SM SP PT OL PT ML/SM GP 28 24 2 17 22 17 4 6 4 5 19 26 5 45 34 34 43 42 36 38 GPSMML ML PT SM PT SP-SM SM CL SP-SM Fill Upper Alluvium Lower AlluviumCPT-8 (Kleinfelder)(13 ft)50 50 Figure 5 Cross Section B-B'\\geoengineers.com\WAN\Projects\24\24939001\CAD\00\Geotech\2493900100_F04-6_Cross Sections.dwg TAB:F05 Date Exported: 03/02/22 - 16:09 by mwoods800 Garden Development Renton, Washington Horizontal Scale in Feet 050 50 Vertical Scale in Feet 020 20 Vertical Exaggeration: 2.5X Legend Notes: 1. The subsurface conditions shown are based on interpolation between widely spaced explorations and should be considered approximate; actual subsurface conditions may vary from those shown. 2. This figure is for informational purposes only. It is intended to assist in the identification of features discussed in a related document. Data were compiled from sources as listed in this figure. The data sources do not guarantee these data are accurate or complete. There may have been updates to the data since the publication of this figure. This figure is a copy of a master document. The hard copy is stored by GeoEngineers, Inc. and will serve as the official document of record. Datum: NAVD 88, unless otherwise noted. Groundwater observed Legend SM 20 Boring Soil Classification Blow CountBoring ID(Offset)Inferred Soil Contact QT (tsf) 0 500 Cone Penetration Test Tip Resistance Fill Upper Alluvium Lower AlluviumCPT ID(Offset) Elevation (Feet)Elevation (Feet)Distance (Feet) -60 -40 -20 0 20 40 60 -60 -40 -20 0 20 40 60 0 50 100 150 200 250 300 350 400 450 500 Existing Grade Existing Building C (West) C' (East)CPT-4(48 ft)B-5(17 ft)B-6(2 ft)B-4(22 ft)QT (tsf) 0 500 25 2 4 GP SM SM/ML SP OL 14 56 5 13 SP OL/PT ML SP PT12 7 9 27 OL PT SP 27 35 44 35 SP 17 12 4 GP SM/ML PT SP SP SP 20 12 39 35 10 15 17 48 OL SP SP 34 35 8 13 GP SP PT GP SP14 12 19 6 SPOL PT SP OL OH 24 43 16 38 51 SP GP SM Fill Upper Alluvium Lower Alluvium 5 27 7 6 2 5 30 7 7 12 9 11 10 19 39 41 65 SM SM OL SM ML PT SP-SM PT SM ML PT CL ML SM SP-SMB-3(110 ft)10' Figure 6 Cross Section C-C'\\geoengineers.com\WAN\Projects\24\24939001\CAD\00\Geotech\2493900100_F04-6_Cross Sections.dwg TAB:F06 Date Exported: 03/02/22 - 16:09 by mwoods800 Garden Development Renton, Washington Horizontal Scale in Feet 050 50 Legend Notes: 1. The subsurface conditions shown are based on interpolation between widely spaced explorations and should be considered approximate; actual subsurface conditions may vary from those shown. 2. This figure is for informational purposes only. It is intended to assist in the identification of features discussed in a related document. Data were compiled from sources as listed in this figure. The data sources do not guarantee these data are accurate or complete. There may have been updates to the data since the publication of this figure. This figure is a copy of a master document. The hard copy is stored by GeoEngineers, Inc. and will serve as the official document of record. Datum: NAVD 88, unless otherwise noted. Groundwater observed Legend SM 20 Boring Soil Classification Blow CountBoring ID(Offset)Inferred Soil Contact QT (tsf) 0 500 Cone Penetration Test Tip Resistance Fill Upper Alluvium Lower Alluvium Vertical Scale in Feet 020 20 Vertical Exaggeration: 2.5XCPT ID(Offset) Materials: SLOPED TO DRAIN AWAY FROM STRUCTURE EXTERIOR WALL WALL DRAINAGE MATERIAL FLOOR SLAB 6 INCHES CAPILLARY BREAK 2' MIN.RETAINED SOIL 4" DIAMETER PERFORATED DRAIN PIPE DAMP PROOFING VAPOR RETARDER, PER PLANS TEMPORARY EXCAVATION SLOPE NOT TO SCALE 12" MIN. COVER OF DRAINAGE MATERIAL (6" MIN. ON SIDES OF PIPE) Figure 7 Wall Drainage and Backfill \\geoengineers.com\WAN\Projects\24\24939001\CAD\00\Geotech\2493900100_F07_Wall Drainage and Backfill.dwg TAB:F07 Date Exported: 03/02/22 - 16:13 by mwoodsPAVEMENT OR 24" LOW PERMEABILITY SOIL A. WALL DRAINAGE MATERIAL: Shall consist of washed gravel such as Seattle Mineral Aggregate Type 5 or "Gravel Backfill for Drains" per WSDOT Standard Specification 9-03.12(4), surrounded with a non-woven geotextile such as Mirafi 140N (or approved equivalent). Alternatively Seattle Mineral Aggregate Type 26 may be used without a geotextile fabric between the drainage material and retained soil. However a minimum of 12 inches of Type 5 or "Gravel Back Fill for Drains" surrounded with a geotextile fabric should be used around the drain pipe. B. RETAINED SOIL: Should consist of structural fill, either on-site soil or imported. The backfill should be compacted in loose lifts not exceeding 6 inches. Wall backfill supporting building floor slabs should consist of imported sand and gravel such as Seattle Mineral Aggregate Type 17 or WSDOT Standard Specification 9-03.14 compacted to at least 95 percent ASTM D1557. Backfill not supporting building floor slabs, sidewalks, or pavement should be compacted to 90 to 92 percent of the maximum dry density, per ASTM D1557. Backfill supporting sidewalks or pavement areas should be compacted to at least 95 percent in the upper two feet. Only hand-operated equipment should be used for compaction within 5 feet of the walls and no heavy equipment should be allowed within 5 feet of the wall. C. CAPILLARY BREAK: Should consist of at least 6 inches of clean crushed gravel with a maximum size of 1-inch and negligible sand or fines, such as Seattle Mineral Aggregate Type 28 or WSDOT Standard Specifications Section 9-03.1(4), grading No. 67. D. PERFORATED DRAIN PIPE: Should consist of a 4-inch diameter perforated heavy-wall solid pipe (SDR-35 PVC) or rigid corrugated polyethylene pipe (ADS N-12) or equivalent. Drain pipes should be placed with 0.25 percent minimum slopes and discharge to the storm water collection system. 800 Garden Development Renton, Washington Figure 8 \\geoengineers.com\WAN\Projects\24\24939001\CAD\00\Geotech\2493900100_F08_Compaction Crtieria.dwg TAB:F08 Date Exported: 03/02/22 - 16:14 by mwoods800 Garden Development Renton, Washington Compaction Criteria for Trench Backfill 95 90 90 9590 Pipe Varies Varies (See Note 1) 2 Feet Varies (Modified Proctor) Pipe Bedding Trench Backfill Base Course Concrete or Asphalt Pavement Maximum Dry Density, by Test Method ASTM D1557 Recommended Compaction as a Percentage of Legend 95 Not To Scale Notes: 1. All backfill under building areas should be compacted to at least 95 percent per ASTM D1557. Non-structural Areas Hardscape Or Pavement Areas Ground Surface 0.01 0.1 1 10 0.01 0.1 15% Damped Spectral Acceleration, Sa(g)Period (seconds) ASCE 7-10 Site Class E MCEr 0.8 x ASCE 7-10 Site Class E MCEr Deterministic (MCE) Response Spectrum Site-Specific Probabilistic MCEr Response Spectrum Recommended Site-Specific MCEr Response Spectrum Recommended Site-Specific MCER Response Spectrum 800 Garden Development Renton, Washington Figure 9 Project: 24939-001-00 Executed: 03/03/2022 APPENDICES APPENDIX A Field Explorations March 10, 2022 | Page A-1 File No. 24939-001-00 APPENDIX A FIELD EXPLORATIONS Subsurface conditions were explored by advancing four mud-rotary borings (B-1 through B-4) and performing eight cone penetration tests (CPT-1 through CPT-8). Borings Subsurface soil and groundwater conditions were evaluated by completing four borings (B-1 through B-4) on February 1 and February 2, 2021. The borings were completed to depths of about 75 feet below the existing ground surface. The boring locations were determined by measuring from existing site features and using a hand-held GPS unit. The approximate boring locations are shown on Figure 2. The borings were completed by Holocene Drilling, Inc. using a truck-mounted drill rig using mud rotary drilling methods. The borings were continuously monitored by a representative from our firm who reviewed and classified the soils encountered, obtained representative samples, observed groundwater conditions and prepared a detailed log of each exploration. The soils encountered in the borings were generally sampled at 2½- and 5-foot vertical intervals with a 2-inch outside-diameter split-barrel standard penetration test (SPT) sampler. The disturbed samples were obtained by driving the sampler 18 inches into the soil with a 140-pound automatic 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 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 in 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 through A-5. The boring 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 relative densities noted on the boring logs are based on the blow count data obtained in the borings and judgment based on the conditions encountered. Observations of groundwater conditions were made during drilling. The groundwater conditions encountered during drilling 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 conditions observed during drilling should be considered approximate. Cone Penetration Tests The eight CPTs (CPT-1 through CPT-8) were completed between February 3 and 5, 2021 by In-Situ Engineering under subcontract to GeoEngineers, Inc. The CPT is a subsurface exploration technique in which a small-diameter steel conical tip with adjacent sleeve is continuously advanced with hydraulically March 10, 2022 | Page A-2 File No. 24939-001-00 operated equipment. Measurements of the tip and sleeve resistance allow interpretation of the soil profile and the consistency of the strata penetrated. The tip resistance, friction ratio and pore water pressure are recorded on the CPT logs. The approximate CPT locations are shown on Figure 2. The logs of the CPT soundings are presented on Figures A-6 through A-13. The CPT soundings were backfilled in accordance with procedures outlined by the Washington State Department of Ecology. SYMBOLS TYPICAL DESCRIPTIONS GW GP SW SP SM FINEGRAINED SOILS SILTS ANDCLAYS NOTE: Multiple symbols are used to indicate borderline or dual soil classifications MORE THAN 50%RETAINED ONNO. 200 SIEVE MORE THAN 50%PASSINGNO. 200 SIEVE GRAVEL ANDGRAVELLYSOILS SC LIQUID LIMITLESS THAN 50 (APPRECIABLE AMOUNTOF FINES) (APPRECIABLE AMOUNTOF FINES) COARSEGRAINEDSOILS MAJOR DIVISIONS GRAPH LETTER GM GC ML CL OL SILTS AND CLAYS SANDS WITHFINES SANDANDSANDY SOILS MH CH OH PT (LITTLE OR NO FINES) CLEAN SANDS GRAVELS WITHFINES CLEAN GRAVELS (LITTLE OR NO FINES) WELL-GRADED GRAVELS, GRAVEL -SAND MIXTURES CLAYEY GRAVELS, GRAVEL - SAND -CLAY MIXTURES WELL-GRADED SANDS, GRAVELLYSANDS POORLY-GRADED SANDS, GRAVELLYSAND SILTY SANDS, SAND - SILT MIXTURES CLAYEY SANDS, SAND - CLAYMIXTURES INORGANIC SILTS, ROCK FLOUR,CLAYEY SILTS WITH SLIGHTPLASTICITY INORGANIC CLAYS OF LOW TOMEDIUM PLASTICITY, GRAVELLYCLAYS, SANDY CLAYS, SILTY CLAYS,LEAN CLAYS ORGANIC SILTS AND ORGANIC SILTYCLAYS OF LOW PLASTICITY INORGANIC SILTS, MICACEOUS ORDIATOMACEOUS SILTY SOILS INORGANIC CLAYS OF HIGHPLASTICITY ORGANIC CLAYS AND SILTS OFMEDIUM TO HIGH PLASTICITY PEAT, HUMUS, SWAMP SOILS WITHHIGH ORGANIC CONTENTSHIGHLY ORGANIC SOILS SOIL CLASSIFICATION CHART MORE THAN 50%OF COARSEFRACTION RETAINEDON NO. 4 SIEVE MORE THAN 50%OF COARSEFRACTION PASSINGON NO. 4 SIEVE SILTY GRAVELS, GRAVEL - SAND -SILT MIXTURES POORLY-GRADED GRAVELS,GRAVEL - SAND MIXTURES LIQUID LIMIT GREATERTHAN 50 Continuous Coring Bulk or grab Direct-Push Piston Shelby tube Standard Penetration Test (SPT) 2.4-inch I.D. split barrel 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 berepresentative of subsurface conditions at other locations or times. Blowcount is recorded for driven samplers as the number ofblows required to advance sampler 12 inches (or distance noted).See exploration log for hammer weight and drop. "P" indicates sampler pushed using the weight of the drill rig. "WOH" indicates sampler pushed using the weight of thehammer. Key to Exploration Logs Figure A-1 Sampler Symbol Descriptions ADDITIONAL MATERIAL SYMBOLS NSSSMSHS SYMBOLS Asphalt Concrete Cement Concrete Crushed Rock/Quarry Spalls Topsoil GRAPH LETTER AC CC SOD Sod/Forest Duff CR DESCRIPTIONS TYPICAL TS %F%GALCACPCSDDDSHAMCMDMohsOCPMPIPLPPSATXUCVS Groundwater Contact Measured groundwater level in exploration, well, or piezometer Measured free product in well or piezometer Graphic Log Contact Distinct contact between soil strata Approximate contact between soil strata Material Description Contact Contact between geologic units Contact between soil of the same geologic unit Laboratory / Field Tests Percent finesPercent gravelAtterberg limitsChemical analysisLaboratory compaction testConsolidation testDry densityDirect shearHydrometer analysisMoisture contentMoisture content and dry densityMohs hardness scaleOrganic contentPermeability or hydraulic conductivity Plasticity indexPoint load testPocket penetrometerSieve analysisTriaxial compressionUnconfined compressionVane shear Sheen Classification No Visible SheenSlight SheenModerate SheenHeavy Sheen Rev 09/2020 *Blow counts may not be representative due tocobbles Groundwater observed at approximately10 feet during drilling AL (LL = 65, PI = 19) 13 22 138 41 62 311 31 80 40 Approximately 3 inches hot mix asphalt pavement Gray-brown fine to medium gravel with silt, sand andoccasional cobbles (medium dense, moist) (fill) Gray silty fine to medium sand (medium dense, moist) Brown silt with sand, oxidation staining (very stiff,moist) Dark brown peat (medium stiff, wet) (upper alluvium) Gray silty fine sand with organic matter (soft, wet) Dark brown organic silt (soft, wet) Fibrous peat (soft to medium stiff, wet) 1A1B%F 2 3%F 4AMC4B4C 5%F 6 7AL 8A 8BMC 4 9 13 6 18 18 18 18 50/5" * 28 18 5 3 3 4 4 AC GP-GM SM ML PT SM OH PT Notes: 76.5 LSP KMS Holocene Drilling, Inc.Mud Rotary Foremost B-58DrillingEquipmentAutohammer140 (lbs) / 30 (in) Drop WA State Plane NorthNAD83 (feet)1302960184680 34.4NAVD88 Easting (X)Northing (Y) Start TotalDepth (ft) Logged By Checked By End Surface Elevation (ft)Vertical Datum Drilled HammerData SystemDatum Driller DrillingMethod See "Remarks" section for groundwater observed 2/1/20212/1/2021 Note: See Figure A-1 for explanation of symbols.Coordinates Data Source: Horizontal approximated based on site survey. Vertical approximated based on field survey. Sheet 1 of 2Project Number: Project Location: Project: 24939-001-00 Log of Boring B-1 Figure A-2 800 Garden Development Renton, Washington Date:3/4/21 Path:W:\PROJECTS\24\24939001\GINT\2493900100.GPJ DBLibrary/Library:GEOENGINEERS_DF_STD_US_JUNE_2017.GLB/GEI8_GEOTECH_STANDARD_%F_NO_GWREMARKS MoistureContent (%)FinesContent (%)FIELD DATA MATERIALDESCRIPTION Sample NameTestingRecovered (in)IntervalBlows/footCollected SampleDepth (feet)0 5 10 15 20 25 30 35 Graphic LogGroupClassificationElevation (feet)302520151050 AL (LL = 52, PI = 27) 413 19 51 22 20 26 22 9 Gray silty fine to medium sand (dense, wet) Gray lean clay with occasional sand interbeds (mediumstiff, wet) Light brown fat clay (stiff, wet) Grayish brown silty fine to medium sand (mediumdense, wet) (lower alluvium) Brown fine to medium sand with silt (dense to verydense, wet) 9MC 10%F 11 12AL 13%F 14%F 15 16 17 18 11 12 17 15 11 15 12 13 6 38 7 12 28 40 50 56 60 SM CL ML SM SP-SM Sheet 2 of 2Project Number: Project Location: Project: 24939-001-00 Log of Boring B-1 (continued) Figure A-2 800 Garden Development Renton, Washington Date:3/4/21 Path:W:\PROJECTS\24\24939001\GINT\2493900100.GPJ DBLibrary/Library:GEOENGINEERS_DF_STD_US_JUNE_2017.GLB/GEI8_GEOTECH_STANDARD_%F_NO_GWREMARKS MoistureContent (%)FinesContent (%)FIELD DATA MATERIALDESCRIPTION Sample NameTestingRecovered (in)IntervalBlows/footCollected SampleDepth (feet)35 40 45 50 55 60 65 70 75 Graphic LogGroupClassificationElevation (feet)-5-10-15-20-25-30-35-40 Groundwater observed at approximately9 feet during drilling 21 210 42 257 304 37 60 38 10 Approximately 11 inches hot mix asphalt pavement Brown fine to coarse gravel with sand and occasionalcobbles (medium dense, moist) (fill) Gray silty fine to medium sand with gravel (mediumdense, moist) Gray sandy silt with gravel (very stiff, moist) Gray silt with sand and occasional gravel (very stiff,moist) Dark brown fibrous peat (soft, wet) (upper alluvium) Gray silty fine to medium sand (loose, wet) Dark brown fibrous peat (soft, wet) With solid wood, becomes medium stiff Gray fine to medium sand with silt and occasionalorganic matter (medium dense, wet) 1A 1B 2%F 3 4MC 5%F 6MC 7MC 8%F 18 13 14 15 11 18 15 11 17 22 17 4 6 4 5 19 AC GP SM ML ML PT SM PT SP-SM Notes: 76.5 LSP KMS Holocene Drilling, Inc.Mud Rotary Foremost B-58DrillingEquipmentAutohammer140 (lbs) / 30 (in) Drop WA State Plane NorthNAD83 (feet)1303100184470 33.83NAVD88 Easting (X)Northing (Y) Start TotalDepth (ft) Logged By Checked By End Surface Elevation (ft)Vertical Datum Drilled HammerData SystemDatum Driller DrillingMethod See "Remarks" section for groundwater observed 2/1/20212/1/2021 Note: See Figure A-1 for explanation of symbols.Coordinates Data Source: Horizontal approximated based on site survey. Vertical approximated based on field survey. Sheet 1 of 2Project Number: Project Location: Project: 24939-001-00 Log of Boring B-2 Figure A-3 800 Garden Development Renton, Washington Date:3/4/21 Path:W:\PROJECTS\24\24939001\GINT\2493900100.GPJ DBLibrary/Library:GEOENGINEERS_DF_STD_US_JUNE_2017.GLB/GEI8_GEOTECH_STANDARD_%F_NO_GWREMARKS MoistureContent (%)FinesContent (%)FIELD DATA MATERIALDESCRIPTION Sample NameTestingRecovered (in)IntervalBlows/footCollected SampleDepth (feet)0 5 10 15 20 25 30 35 Graphic LogGroupClassificationElevation (feet)302520151050 56 17 6 Without organic matter Brown silty fine to medium sand (loose, wet) Gray lean clay (medium stiff, wet) Gray fine sand with silt (dense, wet) (lower alluvium) 9 10A10BMC 11 12%F 13 14 15 16 17 12 12 14 17 16 15 15 16 13 26 5 45 34 34 43 42 36 38 SM CL SP-SM Sheet 2 of 2Project Number: Project Location: Project: 24939-001-00 Log of Boring B-2 (continued) Figure A-3 800 Garden Development Renton, Washington Date:3/4/21 Path:W:\PROJECTS\24\24939001\GINT\2493900100.GPJ DBLibrary/Library:GEOENGINEERS_DF_STD_US_JUNE_2017.GLB/GEI8_GEOTECH_STANDARD_%F_NO_GWREMARKS MoistureContent (%)FinesContent (%)FIELD DATA MATERIALDESCRIPTION Sample NameTestingRecovered (in)IntervalBlows/footCollected SampleDepth (feet)35 40 45 50 55 60 65 70 75 Graphic LogGroupClassificationElevation (feet)-5-10-15-20-25-30-35-40 Groundwater observed at approximately7½ feet during drilling AL (LL = 46, PI = 18) 14 49 30 54 434 15 237 39 18 6 Approximately 4 inches hot mix asphalt pavement Gray-brown silty medium sand with gravel (fill) Gray silty sand (medium dense, moist) With organic matter, becomes wet Brown organic silt (medium stiff, wet) (upper alluvium) Brownish gray silty sand with organic matter (loose,wet) Gray silt (very soft, wet) Brown fibrous peat with solid wood (medium stiff, wet) Gray fine to coarse sand with silt (medium dense, wet) Brown amorphous peat (medium stiff, wet) 1 2%F 3 4AMC4B%F 5AL 6MC 7%F 8MC 2 8 15 17 18 14 16 5 27 7 6 2 5 30 7 AC SM SM OL SM ML PT SP-SM PT Notes: 76.5 LSP KMS Holocene Drilling, Inc.Mud Rotary Foremost B-58DrillingEquipmentAutohammer140 (lbs) / 30 (in) Drop WA State Plane NorthNAD83 (feet)1302990183990 34.08NAVD88 Easting (X)Northing (Y) Start TotalDepth (ft) Logged By Checked By End Surface Elevation (ft)Vertical Datum Drilled HammerData SystemDatum Driller DrillingMethod See "Remarks" section for groundwater observed 2/2/20212/2/2021 Note: See Figure A-1 for explanation of symbols.Coordinates Data Source: Horizontal approximated based on site survey. Vertical approximated based on field survey. Sheet 1 of 2Project Number: Project Location: Project: 24939-001-00 Log of Boring B-3 Figure A-4 800 Garden Development Renton, Washington Date:3/4/21 Path:W:\PROJECTS\24\24939001\GINT\2493900100.GPJ DBLibrary/Library:GEOENGINEERS_DF_STD_US_JUNE_2017.GLB/GEI8_GEOTECH_STANDARD_%F_NO_GWREMARKS MoistureContent (%)FinesContent (%)FIELD DATA MATERIALDESCRIPTION Sample NameTestingRecovered (in)IntervalBlows/footCollected SampleDepth (feet)0 5 10 15 20 25 30 35 Graphic LogGroupClassificationElevation (feet)302520151050 225 39 171 31 21 45 7 Gray silty fine sand (medium dense, wet) Gray silt (stiff, wet) Brown to dark brown fibrous peat (stiff, wet) Gray lean clay (stiff, wet) Brown silt with sand (very stiff, wet) Grayish brown silty fine sand (medium dense, wet) Gray fine to medium sand with silt (dense, wet) (loweralluvium) Becomes brownish gray, very dense 9MC 10%F 11 12MC 13MC 14A 14B 15%F 16 17 18 15 18 18 15 16 17 14 11 7 12 9 11 10 19 39 41 65 SM ML PT CL ML SM SP-SM Sheet 2 of 2Project Number: Project Location: Project: 24939-001-00 Log of Boring B-3 (continued) Figure A-4 800 Garden Development Renton, Washington Date:3/4/21 Path:W:\PROJECTS\24\24939001\GINT\2493900100.GPJ DBLibrary/Library:GEOENGINEERS_DF_STD_US_JUNE_2017.GLB/GEI8_GEOTECH_STANDARD_%F_NO_GWREMARKS MoistureContent (%)FinesContent (%)FIELD DATA MATERIALDESCRIPTION Sample NameTestingRecovered (in)IntervalBlows/footCollected SampleDepth (feet)35 40 45 50 55 60 65 70 75 Graphic LogGroupClassificationElevation (feet)-5-10-15-20-25-30-35-40 Groundwater observed at approximately8 feet during drilling172 40 17 25 10 Approximately 4 inches hot mix asphalt Gray fine to coarse gravel with occasional silt and sand(medium dense, moist) (fill) Brown-gray sandy silt with occasional gravel (very stiff,moist) Oxidation staining Gray-brown organic silt with sand and gravel (mediumstiff) Dark brown fibrous peat (stiff, wet) (upper alluvium) Dark gray silty fine to medium sand with organic matter(very loose, wet) Gray fine to coarse sand with silt, gravel and occasionalcobbles (medium dense, wet) Dark brown fibrous peat (stiff, wet) 1A1B 2 3A3BMC 4 5%F 6 7 8A%F8B 16 15 16 1 10 12 9 9 23 23 7 5 3 26 24 38 AC GP-GM ML ML PT SM SP-SM PT Notes: 76.5 LSP KMS Holocene Drilling, Inc.Mud Rotary Diedrich D-90DrillingEquipmentAutohammer140 (lbs) / 30 (in) Drop WA State Plane NorthNAD83 (feet)1303260183940 34.89NAVD88 Easting (X)Northing (Y) Start TotalDepth (ft) Logged By Checked By End Surface Elevation (ft)Vertical Datum Drilled HammerData SystemDatum Driller DrillingMethod See "Remarks" section for groundwater observed 2/2/20212/2/2021 Note: See Figure A-1 for explanation of symbols.Coordinates Data Source: Horizontal approximated based on site survey. Vertical approximated based on field survey. Sheet 1 of 2Project Number: Project Location: Project: 24939-001-00 Log of Boring B-4 Figure A-5 800 Garden Development Renton, Washington Date:3/4/21 Path:W:\PROJECTS\24\24939001\GINT\2493900100.GPJ DBLibrary/Library:GEOENGINEERS_DF_STD_US_JUNE_2017.GLB/GEI8_GEOTECH_STANDARD_%F_NO_GWREMARKS MoistureContent (%)FinesContent (%)FIELD DATA MATERIALDESCRIPTION Sample NameTestingRecovered (in)IntervalBlows/footCollected SampleDepth (feet)0 5 10 15 20 25 30 35 Graphic LogGroupClassificationElevation (feet)302520151050 AL (LL = 26, PI = 11) 88 37 27 17 64 6 Gray sandy silt with interbedded peat layers (stiff, wet) Gray lean clay (very stiff, wet) Becomes brown, stiff Gray silty fine to medium sand (medium dense, wet) Gray fine to coarse sand with silt (dense to very dense,wet) (lower alluvium) Gray sandy silt with gravel (hard, wet) 9MC 10%F 11AL 12 13 14%F 15 16A 16B16C 17 13 16 9 18 5 16 15 17 18 12 12 19 13 17 45 44 78 40 ML CL SM SP-SM ML Sheet 2 of 2Project Number: Project Location: Project: 24939-001-00 Log of Boring B-4 (continued) Figure A-5 800 Garden Development Renton, Washington Date:3/4/21 Path:W:\PROJECTS\24\24939001\GINT\2493900100.GPJ DBLibrary/Library:GEOENGINEERS_DF_STD_US_JUNE_2017.GLB/GEI8_GEOTECH_STANDARD_%F_NO_GWREMARKS MoistureContent (%)FinesContent (%)FIELD DATA MATERIALDESCRIPTION Sample NameTestingRecovered (in)IntervalBlows/footCollected SampleDepth (feet)35 40 45 50 55 60 65 70 75 Graphic LogGroupClassificationElevation (feet)-5-10-15-20-25-30-35-40 CPT_01 CPT CONTRACTOR: In Situ Engineering CUSTOMER: GeoEngineers INCLOCATION: RentonJOB NUMBER: 24939-001-00COMMENT: 800 Garden DevelopmentCOMMENT: OPERATOR: Okbay CONE ID: DDG1369TEST DATE: 2/5/2021 8:25:49 AMPREDRILL: 4.5 ft BACKFILL: 20% Grout & Bentonite ChipsSURFACE PATCH: Cold Patch TOTAL DEPTH: 75.295 ft Depth (ft) Tip COR (tsf) 0 6000 10 20 30 40 50 60 70 80 Sleeve Stress (tsf) 08 F.Ratio (%) 0 10 Pore Pressure (psi) -20 160 SBT FR (RC 1983) 1 sensitive fine grained 2 organic material 3 clay 4 silty clay to clay 5 clayey silt to silty clay 6 sandy silt to clayey silt 7 silty sand to sandy silt 8 sand to silty sand 9 sand 10 gravelly sand to sand 11 very stiff fine grained (*) 12 sand to clayey sand (*) *SBT/SPT CORRELATION: UBC-1983 0 12 SPT (blows/ft) 0 100 Figure A-6 CPT-02 CPT CONTRACTOR: In Situ Engineering CUSTOMER: GeoEngineers INCLOCATION: RentonJOB NUMBER: 24939-001-00COMMENT: 800 Garden DevelopmentCOMMENT: OPERATOR: Okbay CONE ID: DDG1369TEST DATE: 2/3/2021 11:15:00 AMPREDRILL: 4.5 ft BACKFILL: 20% Grout & Bentonite ChipsSURFACE PATCH: Cold Patch TOTAL DEPTH: 65.617 ft Depth (ft) Tip COR (tsf) 0 7000 10 20 30 40 50 60 70 80 Sleeve Stress (tsf) 08 F.Ratio (%) 0 10 Pore Pressure (psi) -20 160 SBT FR (RC 1983) 1 sensitive fine grained 2 organic material 3 clay 4 silty clay to clay 5 clayey silt to silty clay 6 sandy silt to clayey silt 7 silty sand to sandy silt 8 sand to silty sand 9 sand 10 gravelly sand to sand 11 very stiff fine grained (*) 12 sand to clayey sand (*) *SBT/SPT CORRELATION: UBC-1983 0 12 SPT (blows/ft) 0 100 Figure A-7 CPT-03A CPT CONTRACTOR: In Situ Engineering CUSTOMER: GeoEngineers INCLOCATION: RentonJOB NUMBER: 24939-001-00COMMENT: 800 Garden DevelopmentCOMMENT: OPERATOR: Okbay CONE ID: DDG1369TEST DATE: 2/3/2021 9:27:58 AMPREDRILL: 3.0 ft BACKFILL: 20% Grout & Bentonite ChipsSURFACE PATCH: Cold Patch TOTAL DEPTH: 75.295 ft Depth (ft) Tip COR (tsf) 0 6000 10 20 30 40 50 60 70 80 Sleeve Stress (tsf) 08 F.Ratio (%) 0 10 Pore Pressure (psi) -20 160 SBT FR (RC 1983) 1 sensitive fine grained 2 organic material 3 clay 4 silty clay to clay 5 clayey silt to silty clay 6 sandy silt to clayey silt 7 silty sand to sandy silt 8 sand to silty sand 9 sand 10 gravelly sand to sand 11 very stiff fine grained (*) 12 sand to clayey sand (*) *SBT/SPT CORRELATION: UBC-1983 0 12 SPT (blows/ft) 0 100 Figure A-8 CPT-04 CPT CONTRACTOR: In Situ Engineering CUSTOMER: GeoEngineers INCLOCATION: RentonJOB NUMBER: 24939-001-00COMMENT: 800 Garden DevelopmentCOMMENT: OPERATOR: Okbay CONE ID: DDG1369TEST DATE: 2/3/2021 2:13:48 PMPREDRILL: 4.5 ft BACKFILL: 20% Grout & Bentonite ChipsSURFACE PATCH: Cold Patch TOTAL DEPTH: 75.459 ft Depth (ft) Tip COR (tsf) 0 6000 10 20 30 40 50 60 70 80 Sleeve Stress (tsf) 08 F.Ratio (%) 0 10 Pore Pressure (psi) -20 160 SBT FR (RC 1983) 1 sensitive fine grained 2 organic material 3 clay 4 silty clay to clay 5 clayey silt to silty clay 6 sandy silt to clayey silt 7 silty sand to sandy silt 8 sand to silty sand 9 sand 10 gravelly sand to sand 11 very stiff fine grained (*) 12 sand to clayey sand (*) *SBT/SPT CORRELATION: UBC-1983 0 12 SPT (blows/ft) 0 100 Figure A-9 CPT-05 CPT CONTRACTOR: In Situ Engineering CUSTOMER: GeoEngineers INCLOCATION: RentonJOB NUMBER: 24939-001-00COMMENT: 800 Garden DevelopmentCOMMENT: OPERATOR: Okbay CONE ID: DDG1369TEST DATE: 2/3/2021 3:42:32 PMPREDRILL: 4.5 ft BACKFILL: 20% Grout & Bentonite ChipsSURFACE PATCH: Cold Patch TOTAL DEPTH: 48.720 ft Depth (ft) Tip COR (tsf) 0 8000 10 20 30 40 50 60 70 80 Sleeve Stress (tsf) 09 F.Ratio (%) 0 10 Pore Pressure (psi) -20 160 SBT FR (RC 1983) 1 sensitive fine grained 2 organic material 3 clay 4 silty clay to clay 5 clayey silt to silty clay 6 sandy silt to clayey silt 7 silty sand to sandy silt 8 sand to silty sand 9 sand 10 gravelly sand to sand 11 very stiff fine grained (*) 12 sand to clayey sand (*) *SBT/SPT CORRELATION: UBC-1983 0 12 SPT (blows/ft) 0 100 Figure A-10 CPT_06 CPT CONTRACTOR: In Situ Engineering CUSTOMER: GeoEngineers INCLOCATION: RentonJOB NUMBER: 24939-001-00COMMENT: 800 Garden DevelopmentCOMMENT: OPERATOR: Okbay CONE ID: DDG1369TEST DATE: 2/5/2021 1:05:08 PMPREDRILL: 2.0 ft BACKFILL: 20% Grout & Bentonite ChipsSURFACE PATCH: Cold Patch TOTAL DEPTH: 41.339 ft Depth (ft) Tip COR (tsf) 0 6000 10 20 30 40 50 60 70 80 Sleeve Stress (tsf) 08 F.Ratio (%) 0 10 Pore Pressure (psi) -20 160 SBT FR (RC 1983) 1 sensitive fine grained 2 organic material 3 clay 4 silty clay to clay 5 clayey silt to silty clay 6 sandy silt to clayey silt 7 silty sand to sandy silt 8 sand to silty sand 9 sand 10 gravelly sand to sand 11 very stiff fine grained (*) 12 sand to clayey sand (*) *SBT/SPT CORRELATION: UBC-1983 0 12 SPT (blows/ft) 0 100 Figure A-11 CPT-07 CPT CONTRACTOR: In Situ Engineering CUSTOMER: GeoEngineers INCLOCATION: RentonJOB NUMBER: 24939-001-00COMMENT: 800 Garden DevelopmentCOMMENT: OPERATOR: Okbay CONE ID: DDG1369TEST DATE: 2/3/2021 12:29:51 PMPREDRILL: 4.5 ft BACKFILL: 20% Grout & Bentonite ChipsSURFACE PATCH: Cold Patch TOTAL DEPTH: 65.289 ft Depth (ft) Tip COR (tsf) 0 6000 10 20 30 40 50 60 70 80 Sleeve Stress (tsf) 08 F.Ratio (%) 0 10 Pore Pressure (psi) -20 160 SBT FR (RC 1983) 1 sensitive fine grained 2 organic material 3 clay 4 silty clay to clay 5 clayey silt to silty clay 6 sandy silt to clayey silt 7 silty sand to sandy silt 8 sand to silty sand 9 sand 10 gravelly sand to sand 11 very stiff fine grained (*) 12 sand to clayey sand (*) *SBT/SPT CORRELATION: UBC-1983 0 12 SPT (blows/ft) 0 100 Figure A-12 sCPT_08 CPT CONTRACTOR: In Situ Engineering CUSTOMER: GeoEngineers INCLOCATION: RentonJOB NUMBER: 24939-001-00COMMENT: 800 Garden DevelopmentCOMMENT: OPERATOR: Okbay CONE ID: DDG1369TEST DATE: 2/5/2021 10:09:11 AMPREDRILL: 2 ft BACKFILL: 20% Grout & Bentonite ChipsSURFACE PATCH: Cold Patch TOTAL DEPTH: 91.699 ft Depth (ft) Tip COR (tsf) 0 6000 10 20 30 40 50 60 70 80 90 100 F.Ratio (%) 0 10 Pore Pressure (psi) -20 140 SBT FR (RC 1983) 1 sensitive fine grained 2 organic material 3 clay 4 silty clay to clay 5 clayey silt to silty clay 6 sandy silt to clayey silt 7 silty sand to sandy silt 8 sand to silty sand 9 sand 10 gravelly sand to sand 11 very stiff fine grained (*) 12 sand to clayey sand (*) *SBT/SPT CORRELATION: UBC-1983 0 12 SPT (blows/ft) 0 100 Seismic Velocity (ft/s) 0 1400 Figure A-13 APPENDIX B Laboratory Testing March 10, 2022 | Page B-1 File No. 24939-001-00 APPENDIX B LABORATORY TESTING Soil samples obtained from the borings 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 moisture content, fines content, Atterberg limits and sieve analyses. The tests were performed in general accordance with test methods of ASTM International (ASTM) or other applicable procedures. Moisture Content Moisture content tests of selected samples were completed in general accordance with ASTM D 2216. The results of these tests are presented on the exploration logs in Appendix A at the depths at which the samples were obtained. Percent Fines Determination Selected samples were “washed” through the U.S. No. 200-mesh sieve to estimate the relative percentages of coarse- and fine-grained particles in the soil. The tests were conducted in general accordance with ASTM D 1140. 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 estimate the fines content for analysis purposes. The test results are shown on the exploration logs at the respective sample depths. Atterberg Limits Atterberg limit tests were completed for selected soil samples. The tests were used to classify the soil as well as to aid in evaluating index properties and consolidation characteristics of the fine-grained soil deposits. The liquid limit and the plastic limit were obtained in general accordance with ASTM D 4318. The results of the Atterberg limits are summarized in Figure B-1. Note: This report may not be reproduced, except in full, without written approval of GeoEngineers, Inc. Test results are applicable only to the specific sample on which they were performed, and should not be interpreted as representative of any other samples obtained at other times, depths or locations, or generated by separate operations or processes. The liquid limit and plasticity index were obtained in general accordance with ASTM D 4318. GeoEngineers 17425 NE Union Hill Road Ste 250, Redmond, WA 98052 Figure B-1 Atterberg Limits Test Results 800 Garden Development Renton, Washington 24939-001-00 Date Exported: 02.23.2021Symbol Boring Number Depth (feet) Moisture Content (%) Liquid Limit (%) Plasticity Index (%)Soil Description BH-1 BH-1 BH-3 BH-4 25 50 15 45 62 51 54 27 65 52 46 26 19 27 18 11 Elastic silt (MH) Fat clay (CH) Silt (ML) Lean clay (CL) 0 10 20 30 40 50 60 0 10 20 30 40 50 60 70 80 90 100PLASTICITY INDEX LIQUID LIMIT PLASTICITY CHART CL-ML ML or OL CL or OL OH or MH CH or OH APPENDIX C Boring Logs from Previous Studies March 10, 2022 | Page C-1 File No. 24939-001-00 APPENDIX C EXPLORATIONS FROM PREVIOUS STUDIES Appendix C includes boring logs from the following previous studies completed at and in the vicinity of the project site: ■ The logs of 20 borings (B-1 through B-20) completed in 2001 by Kleinfelder, Inc. ■ The logs of three borings (B-2, B-6, and B-7) completed in 2006 by GeoEngineers, Inc. The approximate locations of these explorations are shown in Figure 2. 2½ inches asphalt concrete Brown silty fine to coarse sand with gravel (wet) (fill) Gray silty fine to medium sand with gravel (dense, moist) Grades to loose, wet Dark brown peat with lenses of gray silty fine to medium sand (medium stiff, wet) (upper alluvialdeposits) Gray silty fine sand with thin lenses of peat (very looseto loose, wet) Brown organic silt with thin lenses of gray fine tomedium sand with silt (medium stiff, wet) Gray silty fine to medium sand with thin lenses oforganic silt (medium dense, wet) Organic silt (medium stiff, wet) Dark brown peat (medium stiff, wet) pH = 7.0 pH = 7.4 OC = 20% AL; OC = 9% %F = 16 pH = 4.6 12 18 18 18 18 18 18 18 AC SM SM PT SM OH SM OL PT 31 4 6 4 4 5 11 6 9 1 2 3 4 5 6 7 8 9 10 9 8 125 92 40 157 Dry UnitWeight, lbs/ft3MATERIAL DESCRIPTION MoistureContent %OTHER TESTS AND NOTES SAMPLES Depth feetIntervalBlows/footWater LevelSub-SampleSample NumberGroupSymbolGraphicLogRecovered (in)Elevation feetGeologic Drill LCF Drilling Method 140 lb hammer/30 in drop rope and cathead Drilling Equipment Deeprock XL Trailer-mounted Drill Rig Checked ByDate(s) Drilled 30 Drilling Contractor Logged By Hammer Data Datum/ System Easting(x): Northing(y): Hollow-stem Auger Auger Data SPT Surface Elevation (ft) Sampling Methods 01/03/06 KGO Vertical Datum 26Groundwater Elevation (ft)Total Depth (ft)80 3.75-inch ID Note: See Figure A-1 for explanation of symbols. 30 25 20 15 10 5 0 -5 0 5 10 15 20 25 30 35 Sheet 1 of 3 LOG OF BORING B-3 Project: Project Location: Project Number: Renton, Washington Lowe's of Renton 8335-003-00 Figure A-4 V6_GTBORING P:\8\8335003\00\FINALS\833500300.GPJ GEIV6_1.GDT 1/26/06 Gray silty fine sand with thin lenses of organic matter (loose, wet) Gray fine sand with lenses of organic silt (loose, wet) (soft, wet) Gray fine to medium sand (medium dense, moist) Gray fine to medium sand with silt and thin lenses of organic silt (medium dense, wet) Gray fine to medium sand with silt (medium dense tovery dense, wet) (lower alluvial deposits) %F = 11 12 18 18 18 18 18 18 18 SM OL/PT SP SP-SM SP-SM 10 6 20 25 20 34 53 49 11 12 13 14 15 16 17 18 19 39 Dry UnitWeight, lbs/ft3MATERIAL DESCRIPTION MoistureContent %OTHER TESTS AND NOTES SAMPLES Depth feetIntervalBlows/footWater LevelSub-SampleSample NumberGroupSymbolGraphicLogRecovered (in)Elevation feet-5 -10 -15 -20 -25 -30 -35 -40 -45 35 40 45 50 55 60 65 70 75 Sheet 2 of 3 LOG OF BORING B-3 (continued) Project: Project Location: Project Number: Renton, Washington Lowe's of Renton 8335-003-00 Figure A-4 V6_GTBORING P:\8\8335003\00\FINALS\833500300.GPJ GEIV6_1.GDT 1/26/06 18 46 Dry UnitWeight, lbs/ft3MATERIAL DESCRIPTION MoistureContent %OTHER TESTS AND NOTES SAMPLES Depth feetIntervalBlows/footWater LevelSub-SampleSample NumberGroupSymbolGraphicLogRecovered (in)Elevation feet-50 -55 -60 -65 -70 -75 -80 -85 -90 80 85 90 95 100 105 110 115 120 Sheet 3 of 3 LOG OF BORING B-3 (continued) Project: Project Location: Project Number: Renton, Washington Lowe's of Renton 8335-003-00 Figure A-4 V6_GTBORING P:\8\8335003\00\FINALS\833500300.GPJ GEIV6_1.GDT 1/26/06 2 inches asphalt concrete Brown silty fine to medium sand with occasional gravel(medium dense to dense, moist) (fill) SA; pH = 6.6 Gray silty fine sand with trace organic matter (medium dense, wet) (upper alluvial deposits) Groundwater measured on 01/03/06 Concretesurface seal Bentonite seal 1-inch Schedule 80 PVC wellcasing 10-20 sand backfill 1-inch Schedule 80PVC screen, 0.020-inchslot width 11 10 AC SM SM 18 18 18 12 29 42 37 10 11 1 2 3 4 5 6 WELL CONSTRUCTION MATERIAL DESCRIPTION Elevation feetDry UnitWeight, lbs/ft3MoistureContent %Sub-SampleSample NumberDepth feetBlows/footIntervalGraphic LogGroupSymbolRecovered (in)SAMPLES Geologic Drill LCF 3.75-inch ID Drilling Method 140 lb hammer/30 in drop rope and cathead Drilling Equipment Deeprock XL Trailer-mounted Drill Rig Checked ByDate(s) Drilled Drilling Contractor Logged By Hammer Data Hollow-stem Auger SPT Auger Data Sampling Methods 01/03/06 KGO Datum/ System Easting(x): Northing(y): Vertical Datum 32Total Exploration Depth (ft)16.5 Ground Surface Elevation (ft) Groundwater Elevation (ft)23.5 Steel surface monument Note: See Figure A-1 for explanation of symbols. 0 5 10 15 20 25 30 35 30 25 20 15 10 5 0 Sheet 1 of 1 LOG OF BORING B-4 Project: Project Location: Project Number: Renton, Washington Lowe's of Renton 8335-003-00 Figure A-5 V6_GTWELL P:\8\8335003\00\FINALS\833500300.GPJ GEIV6_1.GDT 1/26/06 1½ inches asphalt concrete Gray silty fine to medium sand with gravel (mediumdense, moist) (fill) pH = 6.6 Grades to loose Brown silty fine to medium sand with gravel and organicmatter (loose, wet) (upper alluvial deposits) Dark brown peat (soft, wet)Gray sandy silt (soft to medium stiff, wet) Gray fine sand with silt and organic matter (loose, wet) Groundwater measured on 01/03/06 Concretesurface seal Bentonite seal 1-inch Schedule 80 PVC wellcasing 10-20 sand backfill 1-inch Schedule 80PVC screen, 0.020-inchslot width 15 18 95 AC SM SM PT ML SP-SM 12 18 12 18 10 14 11 4 4 6 1 2 3 4 5 6 WELL CONSTRUCTION MATERIAL DESCRIPTION Elevation feetDry UnitWeight, lbs/ft3MoistureContent %Sub-SampleSample NumberDepth feetBlows/footIntervalGraphic LogGroupSymbolRecovered (in)SAMPLES Geologic Drill LCF 3.75-inch ID Drilling Method 140 lb hammer/30 in drop rope and cathead Drilling Equipment Deeprock XL Trailer-mounted Drill Rig Checked ByDate(s) Drilled Drilling Contractor Logged By Hammer Data Hollow-stem Auger SPT Auger Data Sampling Methods 01/03/06 KGO Datum/ System Easting(x): Northing(y): Vertical Datum 32.5Total Exploration Depth (ft)16.5 Ground Surface Elevation (ft) Groundwater Elevation (ft)25 Steel surface monument Note: See Figure A-1 for explanation of symbols. 0 5 10 15 20 25 30 35 30 25 20 15 10 5 0 Sheet 1 of 1 LOG OF BORING B-5 Project: Project Location: Project Number: Renton, Washington Lowe's of Renton 8335-003-00 Figure A-6 V6_GTWELL P:\8\8335003\00\FINALS\833500300.GPJ GEIV6_1.GDT 1/26/06 1¾ inches asphalt concrete 1 inch base courseGray sandy silt with occasional gravel (very stiff to hard, moist) (fill) Gray silty fine to medium sand with gravel and occasional wood debris (dense, wet) (fill) Dark brown peat (medium stiff to stiff, moist) (upper alluvial deposits) Gray silty fine sand (loose, moist) SA; pH = 7.7 OC = 15% 12 12 12 12 12 AC GP SM/ML SM PT SM 37 32 36 35 9 1 2 3 4 5 6 13 15 13 81 Dry UnitWeight, lbs/ft3MATERIAL DESCRIPTION MoistureContent %OTHER TESTS AND NOTES SAMPLES Depth feetIntervalBlows/footWater LevelSub-SampleSample NumberGroupSymbolGraphicLogRecovered (in)Elevation feetGeologic Drill LCF Drilling Method 140 lb hammer/30 in drop rope and cathead Drilling Equipment Deeprock XL Trailer-mounted Drill Rig Checked ByDate(s) Drilled 35 Drilling Contractor Logged By Hammer Data Datum/ System Easting(x): Northing(y): Hollow-stem Auger Auger Data SPT Surface Elevation (ft) Sampling Methods 01/03/06 KGO Vertical Datum 34.25Groundwater Elevation (ft)Total Depth (ft)16.5 3.75-inch ID Note: See Figure A-1 for explanation of symbols. 35 30 25 20 15 10 5 0 0 5 10 15 20 25 30 35 Sheet 1 of 1 LOG OF BORING B-6 Project: Project Location: Project Number: Renton, Washington Lowe's of Renton 8335-003-00 Figure A-7 V6_GTBORING P:\8\8335003\00\FINALS\833500300.GPJ GEIV6_1.GDT 1/26/06 1¾ inches asphalt concrete 1 inch base courseBrownish gray silty fine to medium sand with gravel (medium dense to dense, moist) (fill) pH = 7.7 pH = 6.0 Dark brown peat (medium stiff, moist) (upper alluvial deposits) Gray silty fine sand (loose, moist) Gray fine sand with silt and thin lenses of organic matter (loose, wet) Groundwater measured on 01/03/06 Concrete surface seal Bentonite seal 1-inchSchedule 80 PVC wellcasing 10-20 sand backfill 1-inchSchedule 80 PVC screen,0.020-inch slot width 14 19 276 AC GP SM PT SM SP-SM 10 2 18 18 18 27 43 13 8 5 1 2 3 4 5 6 WELL CONSTRUCTION MATERIAL DESCRIPTION Elevation feetDry UnitWeight, lbs/ft3MoistureContent %Sub-SampleSample NumberDepth feetBlows/footIntervalGraphic LogGroupSymbolRecovered (in)SAMPLES Geologic Drill LCF 3.75-inch ID Drilling Method 140 lb hammer/30 in drop rope and cathead Drilling Equipment Deeprock XL Trailer-mounted Drill Rig Checked ByDate(s) Drilled Drilling Contractor Logged By Hammer Data Hollow-stem Auger SPT Auger Data Sampling Methods 01/03/06 KGO Datum/ System Easting(x): Northing(y): Vertical Datum 33Total Exploration Depth (ft)16.5 Ground Surface Elevation (ft) Groundwater Elevation (ft)25.5 Steel surface monument Note: See Figure A-1 for explanation of symbols. 0 5 10 15 20 25 30 35 30 25 20 15 10 5 0 Sheet 1 of 1 LOG OF BORING B-7 Project: Project Location: Project Number: Renton, Washington Lowe's of Renton 8335-003-00 Figure A-8 V6_GTWELL P:\8\8335003\00\FINALS\833500300.GPJ GEIV6_1.GDT 1/26/06 APPENDIX D Report Limitations and Guidelines for Use March 10, 2022 | Page D-1 File No. 24939-001-00 APPENDIX D REPORT LIMITATIONS AND GUIDELINES FOR USE1 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 Bay West Development Holdings, LLC and other project team members for the proposed 800 Garden Mixed-use Development in Renton, Washington. 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 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 proposed 800 Garden Mixed-Use Development located 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 structure; ■ Elevation, configuration, location, orientation or weight of the proposed structure; 1 Developed based on material provided by ASFE, Professional Firms Practicing in the Geosciences; www.asfe.org. March 10, 2022 | Page D-2 File No. 24939-001-00 ■ 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. 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. March 10, 2022 | Page D-3 File No. 24939-001-00 Do Not 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. 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. March 10, 2022 | Page D-4 File No. 24939-001-00 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. 800 Garden – Bay West Appendix D Appendix D Project Plans (Note: The plans included with this report are for reference only and are not scalable. For a complete full-size set of plans, refer to the permit submittal.) 1601 5th Avenue, Suite 1600 Seattle, WA 98101 206.622.5822 www.kpff.com IN COMPLIANCE WITH CITY OF RENTON STANDARDS 800 GARDEN800 GARDENLAND USE PERMIT APPLICATION RENTON, WA 98057 800 GARDEN AVE N Call 811 two business days before you dig R NOT FOR CONSTRUCTION PRELIMINARY CIVIL COVER SHEET 800 GARDEN 800 GARDEN AVENUE NORTH, RENTON, WA 98057 SECTION 8, TOWNSHIP 23 NORTH, RANGE 5 EAST, W.M. STOPSTOPSTOPSTOP NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE STOPSTOP· · · 1601 5th Avenue, Suite 1600 Seattle, WA 98101 206.622.5822 www.kpff.com IN COMPLIANCE WITH CITY OF RENTON STANDARDS 800 GARDEN800 GARDENLAND USE PERMIT APPLICATION RENTON, WA 98057 800 GARDEN AVE N Call 811 two business days before you dig R NOT FOR CONSTRUCTION PRELIMINARY GENERALIZED UTILITY PLAN STOPNO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE · · · · · · 1601 5th Avenue, Suite 1600 Seattle, WA 98101 206.622.5822 www.kpff.com IN COMPLIANCE WITH CITY OF RENTON STANDARDS 800 GARDEN800 GARDENLAND USE PERMIT APPLICATION RENTON, WA 98057 800 GARDEN AVE N Call 811 two business days before you dig R NOT FOR CONSTRUCTION PRELIMINARY GENERALIZED UTILITY PLAN STOPSTOPSTOPSTOP NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE STOPSTOP1601 5th Avenue, Suite 1600 Seattle, WA 98101 206.622.5822 www.kpff.com IN COMPLIANCE WITH CITY OF RENTON STANDARDS 800 GARDEN800 GARDENLAND USE PERMIT APPLICATION RENTON, WA 98057 800 GARDEN AVE N Call 811 two business days before you dig R NOT FOR CONSTRUCTION PRELIMINARY GRADING, PAVING, & DRAINAGE PLAN ≥ STOPNO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE NO PARKING FIRE LANE 1601 5th Avenue, Suite 1600 Seattle, WA 98101 206.622.5822 www.kpff.com IN COMPLIANCE WITH CITY OF RENTON STANDARDS 800 GARDEN800 GARDENLAND USE PERMIT APPLICATION RENTON, WA 98057 800 GARDEN AVE N Call 811 two business days before you dig R NOT FOR CONSTRUCTION PRELIMINARY GRADING, PAVING, & DRAINAGE PLAN ≥ 1601 5th Avenue, Suite 1600 Seattle, WA 98101 206.622.5822 www.kpff.com IN COMPLIANCE WITH CITY OF RENTON STANDARDS 800 GARDEN800 GARDENLAND USE PERMIT APPLICATION RENTON, WA 98057 800 GARDEN AVE N Call 811 two business days before you dig R NOT FOR CONSTRUCTION PRELIMINARY TYPICAL SECTIONS 800 Garden – Bay West Appendix E Appendix E Correspondence From: Nathan Janders <NJanders@Rentonwa.gov> Sent: Monday, March 14, 2022 1:16 PM To: Cate Kraska Cc: Thaddeus Egging; Michael Clark Subject: RE: PRE21-000415 - Flow Control Hi Cate, I am not aware of any capacity issues and think that a direct discharge would be viable here. However, I would also urge you to consider looking at the exceptions under section “A. Peak Rate Flow Control Standard Areas” as I believe that the project will likely have very close to the same, if not less, impervious coverage as the current site and therefore would likely result in less then a 0.15 CFS increase in runoff. Regards, NATHAN JANDERS, P.E., Civil Engineer III City of Renton | CED | Planning Division 1055 S Grady Way | 6th Floor | Renton, WA 98057 Virtual Permit Center | Online Applications and Inspections (425) 430-7382 | NJanders@rentonwa.gov From: Cate Kraska <Cate.Kraska@kpff.com> Sent: Friday, March 11, 2022 8:20 AM To: Nathan Janders <NJanders@Rentonwa.gov> Cc: Thaddeus Egging <Thaddeus.Egging@kpff.com>; Michael Clark <Michael.Clark@kpff.com> Subject: PRE21-000415 - Flow Control Hi Nathan – We’d like to confirm our understanding of flow control requirements for the redevelopment at 800 Garden Ave N. It appears the project falls under the direct discharge exemption because it discharges to Johns Creek downstream of I-405. Do you know of any capacity issues in the system that would not allow the project to apply the direct discharge exemption? Would you agree with our understanding of flow control requirements for the project? Thanks! Cate Kraska She / Her / Hers Civil Design Engineer O 206.622.5822 D 206.926.0505 1601 Fifth Avenue, Suite 1600 Seattle, WA 98101 CAUTION: This email originated from outside the City of Renton. Do not click links, reply or open attachments unless you know the content is safe.