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HomeMy WebLinkAboutEX_04_RS_Geotechincal_Report_230825_v1EarthSolutionsNWLLC EarthSolutions NW LLC 15365 N.E.90th Street,Suite 100 Redmond,WA 98052 (425)449-4704 Fax (425)449-4711 www.earthsolutionsnw.com Geotechnical Engineering Construction Observation/Testing Environmental Services GEOTECHNICAL ENGINEERING STUDY PROPOSED RESIDENTIAL DEVELOPMENT TALBOT ROAD PROPERTY 2103 TALBOT ROAD SOUTH RENTON,WASHINGTON ES-9099 RECEIVED 09/08/2023 JDing PLANNING DIVISION DocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C PREPARED FOR SEATTLE LLL, LLC July 18, 2023 _________________________ Brian C. Snow, L.G. Senior Staff Geologist _________________________ Henry T. Wright, P.E. Associate Principal Engineer _________________________ Kyle R. Campbell, P.E. Senior Principal Engineer GEOTECHNICAL ENGINEERING STUDY PROPOSED RESIDENTIAL DEVELOPMENT TALBOT ROAD PROPERTY 2103 TALBOT ROAD SOUTH RENTON, WASHINGTON ES-9099 Earth Solutions NW, LLC 15365 Northeast 90th Street, Suite 100 Redmond, Washington 98052 Phone: 425-449-4704 | Fax: 425-449-4711 www.earthsolutionsnw.com 07/18/2023 07/18/2023 DocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C Geotechnical-Engineering Report Important Information about This Subsurface problems are a principal cause of construction delays, cost overruns, claims, and disputes. While you cannot eliminate all such risks, you can manage them. The following information is provided to help. The Geoprofessional Business Association (GBA) has prepared this advisory to help you – assumedly a client representative – interpret and apply this geotechnical-engineering report as effectively as possible. In that way, you can benefit from a lowered exposure to problems associated with subsurface conditions at project sites and development of them that, for decades, have been a principal cause of construction delays, cost overruns, claims, and disputes. If you have questions or want more information about any of the issues discussed herein, contact your GBA-member geotechnical engineer. Active engagement in GBA exposes geotechnical engineers to a wide array of risk-confrontation techniques that can be of genuine benefit for everyone involved with a construction project. Understand the Geotechnical-Engineering Services Provided for this Report Geotechnical-engineering services typically include the planning, collection, interpretation, and analysis of exploratory data from widely spaced borings and/or test pits. Field data are combined with results from laboratory tests of soil and rock samples obtained from field exploration (if applicable), observations made during site reconnaissance, and historical information to form one or more models of the expected subsurface conditions beneath the site. Local geology and alterations of the site surface and subsurface by previous and proposed construction are also important considerations. Geotechnical engineers apply their engineering training, experience, and judgment to adapt the requirements of the prospective project to the subsurface model(s). Estimates are made of the subsurface conditions that will likely be exposed during construction as well as the expected performance of foundations and other structures being planned and/or affected by construction activities. The culmination of these geotechnical-engineering services is typically a geotechnical-engineering report providing the data obtained, a discussion of the subsurface model(s), the engineering and geologic engineering assessments and analyses made, and the recommendations developed to satisfy the given requirements of the project. These reports may be titled investigations, explorations, studies, assessments, or evaluations. Regardless of the title used, the geotechnical-engineering report is an engineering interpretation of the subsurface conditions within the context of the project and does not represent a close examination, systematic inquiry, or thorough investigation of all site and subsurface conditions. Geotechnical-Engineering Services are Performed for Specific Purposes, Persons, and Projects, and At Specific Times Geotechnical engineers structure their services to meet the specific needs, goals, and risk management preferences of their clients. A geotechnical-engineering study conducted for a given civil engineer will not likely meet the needs of a civil-works constructor or even a different civil engineer. Because each geotechnical-engineering study is unique, each geotechnical-engineering report is unique, prepared solely for the client. Likewise, geotechnical-engineering services are performed for a specific project and purpose. For example, it is unlikely that a geotechnical- engineering study for a refrigerated warehouse will be the same as one prepared for a parking garage; and a few borings drilled during a preliminary study to evaluate site feasibility will not be adequate to develop geotechnical design recommendations for the project. Do not rely on this report if your geotechnical engineer prepared it: • for a different client; • for a different project or purpose; • for a different site (that may or may not include all or a portion of the original site); or • before important events occurred at the site or adjacent to it; e.g., man-made events like construction or environmental remediation, or natural events like floods, droughts, earthquakes, or groundwater fluctuations. Note, too, the reliability of a geotechnical-engineering report can be affected by the passage of time, because of factors like changed subsurface conditions; new or modified codes, standards, or regulations; or new techniques or tools. If you are the least bit uncertain about the continued reliability of this report, contact your geotechnical engineer before applying the recommendations in it. A minor amount of additional testing or analysis after the passage of time – if any is required at all – could prevent major problems. Read this Report in Full Costly problems have occurred because those relying on a geotechnical- engineering report did not read the report in its entirety. Do not rely on an executive summary. Do not read selective elements only. Read and refer to the report in full. You Need to Inform Your Geotechnical Engineer About Change Your geotechnical engineer considered unique, project-specific factors when developing the scope of study behind this report and developing the confirmation-dependent recommendations the report conveys. Typical changes that could erode the reliability of this report include those that affect: • the site’s size or shape; • the elevation, configuration, location, orientation, function or weight of the proposed structure and the desired performance criteria; • the composition of the design team; or • project ownership. As a general rule, always inform your geotechnical engineer of project or site changes – even minor ones – and request an assessment of their impact. The geotechnical engineer who prepared this report cannot accept DocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C responsibility or liability for problems that arise because the geotechnical engineer was not informed about developments the engineer otherwise would have considered. Most of the “Findings” Related in This Report Are Professional Opinions Before construction begins, geotechnical engineers explore a site’s subsurface using various sampling and testing procedures. Geotechnical engineers can observe actual subsurface conditions only at those specific locations where sampling and testing is performed. The data derived from that sampling and testing were reviewed by your geotechnical engineer, who then applied professional judgement to form opinions about subsurface conditions throughout the site. Actual sitewide-subsurface conditions may differ – maybe significantly – from those indicated in this report. Confront that risk by retaining your geotechnical engineer to serve on the design team through project completion to obtain informed guidance quickly, whenever needed. This Report’s Recommendations Are Confirmation-Dependent The recommendations included in this report – including any options or alternatives – are confirmation-dependent. In other words, they are not final, because the geotechnical engineer who developed them relied heavily on judgement and opinion to do so. Your geotechnical engineer can finalize the recommendations only after observing actual subsurface conditions exposed during construction. If through observation your geotechnical engineer confirms that the conditions assumed to exist actually do exist, the recommendations can be relied upon, assuming no other changes have occurred. The geotechnical engineer who prepared this report cannot assume responsibility or liability for confirmation-dependent recommendations if you fail to retain that engineer to perform construction observation. This Report Could Be Misinterpreted Other design professionals’ misinterpretation of geotechnical- engineering reports has resulted in costly problems. Confront that risk by having your geotechnical engineer serve as a continuing member of the design team, to: • confer with other design-team members; • help develop specifications; • review pertinent elements of other design professionals’ plans and specifications; and • be available whenever geotechnical-engineering guidance is needed. You should also confront the risk of constructors misinterpreting this report. Do so by retaining your geotechnical engineer to participate in prebid and preconstruction conferences and to perform construction- phase observations. Give Constructors a Complete Report and Guidance Some owners and design professionals mistakenly believe they can shift unanticipated-subsurface-conditions liability to constructors by limiting the information they provide for bid preparation. To help prevent the costly, contentious problems this practice has caused, include the complete geotechnical-engineering report, along with any attachments or appendices, with your contract documents, but be certain to note conspicuously that you’ve included the material for information purposes only. To avoid misunderstanding, you may also want to note that “informational purposes” means constructors have no right to rely on the interpretations, opinions, conclusions, or recommendations in the report. Be certain that constructors know they may learn about specific project requirements, including options selected from the report, only from the design drawings and specifications. Remind constructors that they may perform their own studies if they want to, and be sure to allow enough time to permit them to do so. Only then might you be in a position to give constructors the information available to you, while requiring them to at least share some of the financial responsibilities stemming from unanticipated conditions. Conducting prebid and preconstruction conferences can also be valuable in this respect. Read Responsibility Provisions Closely Some client representatives, design professionals, and constructors do not realize that geotechnical engineering is far less exact than other engineering disciplines. This happens in part because soil and rock on project sites are typically heterogeneous and not manufactured materials with well-defined engineering properties like steel and concrete. That lack of understanding has nurtured unrealistic expectations that have resulted in disappointments, delays, cost overruns, claims, and disputes. To confront that risk, geotechnical engineers commonly include explanatory provisions in their reports. Sometimes labeled “limitations,” many of these provisions indicate where geotechnical engineers’ responsibilities begin and end, to help others recognize their own responsibilities and risks. Read these provisions closely. Ask questions. Your geotechnical engineer should respond fully and frankly. Geoenvironmental Concerns Are Not Covered The personnel, equipment, and techniques used to perform an environmental study – e.g., a “phase-one” or “phase-two” environmental site assessment – differ significantly from those used to perform a geotechnical-engineering study. For that reason, a geotechnical-engineering report does not usually provide environmental findings, conclusions, or recommendations; e.g., about the likelihood of encountering underground storage tanks or regulated contaminants. Unanticipated subsurface environmental problems have led to project failures. If you have not obtained your own environmental information about the project site, ask your geotechnical consultant for a recommendation on how to find environmental risk-management guidance. Obtain Professional Assistance to Deal with Moisture Infiltration and Mold While your geotechnical engineer may have addressed groundwater, water infiltration, or similar issues in this report, the engineer’s services were not designed, conducted, or intended to prevent migration of moisture – including water vapor – from the soil through building slabs and walls and into the building interior, where it can cause mold growth and material-performance deficiencies. Accordingly, proper implementation of the geotechnical engineer’s recommendations will not of itself be sufficient to prevent moisture infiltration. Confront the risk of moisture infiltration by including building-envelope or mold specialists on the design team. Geotechnical engineers are not building-envelope or mold specialists. Copyright 2019 by Geoprofessional Business Association (GBA). Duplication, reproduction, or copying of this document, in whole or in part, by any means whatsoever, is strictly prohibited, except with GBA’s specific written permission. Excerpting, quoting, or otherwise extracting wording from this document is permitted only with the express written permission of GBA, and only for purposes of scholarly research or book review. Only members of GBA may use this document or its wording as a complement to or as an element of a report of any kind. Any other firm, individual, or other entity that so uses this document without being a GBA member could be committing negligent or intentional (fraudulent) misrepresentation. Telephone: 301/565-2733 e-mail: info@geoprofessional.org www.geoprofessional.org DocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C July 18, 2023 ES-9099 Seattle LLL, LLC 325 – 118th Avenue Southeast, Suite 100 Bellevue, Washington 98005 Attention: Lili Lu Dear Lili: Earth Solutions NW, LLC (ESNW) is pleased to present this geotechnical report for the proposed residential development to be constructed along the west side of Talbot Road South, just west of the intersection with South 21st Street, in Renton, Washington. Based on the results of our investigation, the proposed residential construction is feasible from a geotechnical standpoint. Geologic stratigraphy observed at the subsurface exploration locations generally consisted of about 8 to 30 feet of native glacial till deposits atop competent Renton Formation sandstone and siltstone bedrock, which extended to the maximum exploration depth of about 80 feet below existing grades and to the termination depth of all exploratory borings. The subject site falls entirely within an area identified as a moderate/medium coal mine hazard area per City of Renton GIS mapping. However, based on the results of our investigation, the site can be classified as a low coal mine hazard area. In our opinion, the risk of surface subsidence due to collapsing coal mine workings may be considered very low to negligible based on the competent underlying geology and lack of coal mine related void space encountered at the exploration locations. In our opinion, coal mine hazard area regulations and specialized design considerations regarding potential surface subsidence are not necessary for this project. As such, the typical residential structure proposed to be constructed on this site can be supported on conventional spread and continuous foundations bearing on undisturbed competent native soil, recompacted native soil, or new structural fill placed directly on a competent subgrade. Competent native soil suitable for foundation support is expected to be encountered beginning at depths of about two to three feet below existing grades across the site. The native glacial till and underlying bedrock deposits exhibit very poor infiltration characteristics, including high relative density, high fines content, and weak cementation. In our opinion, full infiltration should be considered infeasible from a geotechnical standpoint. 15365 N.E. 90th Street, Suite 100 • Redmond, WA 98052 • (425) 449-4704 • FAX (425) 449-4711 Earth Solutions NW LLC Geotechnical Engineering, Construction Observation/Testing and Environmental Services DocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C Seattle LLL, LLC ES-9099 July 18, 2023 Executive Summary – Page 2 Earth Solutions NW, LLC This report provides geotechnical analyses and recommendations for the proposed residential development. The opportunity to be of service to you is appreciated. If you have any questions regarding the content of this geotechnical engineering study, please call. Sincerely, EARTH SOLUTIONS NW, LLC Brian C. Snow, L.G. Senior Staff Geologist DocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C Earth Solutions NW, LLC  Table of Contents ES-9099 PAGE INTRODUCTION ................................................................................. 1 General .................................................................................... 1 Project Description ................................................................. 2 SITE CONDITIONS ............................................................................. 3 Surface ..................................................................................... 3 Subsurface .............................................................................. 3 Topsoil and Fill ............................................................. 4 Native Soil ..................................................................... 4 Bedrock ......................................................................... 4 Geologic Setting ........................................................... 5 Groundwater ................................................................. 6 Geologic Critical Areas Review ............................................. 6 Coal Mine Hazard ......................................................... 7 Landslide Hazard.......................................................... 9 DISCUSSION AND RECOMMENDATIONS ....................................... 9 General .................................................................................... 9 Site Preparation and Earthwork ............................................. 10 Temporary Erosion Control ......................................... 10 Excavations and Slopes .............................................. 10 Structural Fill ................................................................ 11 In-situ and Imported Soil ............................................. 12 Wet Season Grading .................................................... 12 Subgrade Preparation .................................................. 13 Void Space Restoration ............................................... 13 Grading and Excavations in Bedrock ......................... 13 Foundations ............................................................................ 13 Retaining Walls ....................................................................... 14 Seismic Design ....................................................................... 15 Slab-on-Grade Floors ............................................................. 16 Utility Support and Trench Backfill ....................................... 16 Preliminary Pavement Sections ............................................. 17 Drainage................................................................................... 17 Infiltration Feasibility ................................................... 18 Preliminary Stormwater Vault Design ........................ 18 LIMITATIONS ...................................................................................... 20 Additional Services ................................................................. 20 DocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C   Earth Solutions NW, LLC Table of Contents Cont’d ES-9099 GRAPHICS Plate 1 Vicinity Map Plate 2 Boring Location Plan Plate 3 Geologic Map Plate 4 Historical Coal Mine Map K32 A Plate 5 LiDAR-Based Shaded Relief Map Plate 6 Retaining Wall Drainage Detail Plate 7 Footing Drain Detail APPENDICES Appendix A Subsurface Exploration Logs Appendix B Laboratory Test Results DocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C Earth Solutions NW, LLC  GEOTECHNICAL ENGINEERING STUDY PROPOSED RESIDENTIAL DEVELOPMENT TALBOT ROAD PROPERTY 2103 TALBOT ROAD SOUTH RENTON, WASHINGTON ES-9099 INTRODUCTION General This geotechnical engineering study was prepared for the proposed residential development to be constructed on the west side of Talbot Road South, just west of the intersection with South 21st Street, in Renton, Washington. The purpose of this study was to provide geotechnical recommendations to support the current development plans, as understood at the time of this study. To fulfill our scope of services, the following tasks were completed:  Subsurface exploration to characterize the soil and groundwater conditions and to assess potential coal mine hazards on site.  Laboratory testing of representative soil samples collected at the exploration locations.  Infiltration feasibility evaluation based primarily on our field observations and laboratory analyses.  Engineering analyses and recommendations for the proposed residential development.  Literature review of historical coal mine maps and related documentation.  Preparation of this report. The following documents and resources were reviewed as part of our report preparation:  Pre-Application Submittal, prepared by D.R. Strong Consulting Engineers, dated October 13, 2022.  Feasibility Layout, prepared by D.R. Strong Consulting Engineers, Project No. 22058, dated July 28, 2022.  Geologic Map of the Renton Quadrangle, King County, Washington, by Mullineaux, D.R., dated 1965.  Web Soil Survey (WSS), online resource maintained by the Natural Resources Conservation Service (NRCS) under the United States Department of Agriculture (USDA). DocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C Seattle LLL, LLC ES-9099 July 18, 2023 Page 2 Earth Solutions NW, LLC  Soil Survey of King County Area, Washington, by Snyder, D.E., Gale, P.S., and Pringle, R.F., USDA Soil Conservation Service, issued November 1973.  Geology of the Renton, Auburn, and Black Diamond Quadrangles, King County, Washington: A Study of Cenozoic Bedrock and Surficial Deposits in the Southeastern Part of the Puget Sound Lowland, Geological Survey Professional Paper 672, by Mullineaux, D.R., United States Geological Survey, dated 1970.  Chapter 4 (Soil and Rock Classification and Logging) of the WSDOT Geotechnical Design Manual, M 46-03.16, dated February 2022.  Geologic Information Portal, online resource maintained by the Washington State Department of Natural Resources (DNR).  Faults and Earthquakes in Washington State, by Czajkowski and Bowman, endorsed by the Washington State Department of Natural Resources, dated 2014.  King County Landslide Hazard Areas, Map 12-1, prepared by Tetra Tech, Inc. and endorsed by the King County Flood Control District, dated May 2010.  King County Liquefaction Susceptibility, Map 11-5, prepared by Tetra Tech, Inc. and endorsed by the King County Flood Control District, dated May 2010.  Renton Municipal Code (RMC) Title IV, Chapter 3, Section 4-3-050. Project Description The subject site consists of a single tax parcel (King County Parcel No. 722200-0175) located on the west side of Talbot Road South, just west of the intersection with South 21st Street, in Renton, Washington. Site-specific development plans were not available for review. However, per the referenced feasibility layout, we understand the site is proposed to be developed with six residential lots, an access road, a stormwater facility, and other associated improvements. At the time of report submission, specific building load values were not available for review; however, we anticipate that typical two- to three-story residential structures will be constructed, consisting of relatively lightly loaded wood framing supported on conventional foundations. Based on our experience with similar developments, we estimate wall loads of about 2 to 3 kips per linear foot and slab-on-grade and column loading of 150 pounds per square foot (psf) will be incorporated into the final design. If the above design assumptions either change or are incorrect, ESNW should be contacted to review the recommendations provided in this report. ESNW should review final designs to verify the geotechnical recommendations provided in this report have been incorporated into the plans. DocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C Seattle LLL, LLC ES-9099 July 18, 2023 Page 3 Earth Solutions NW, LLC SITE CONDITIONS Surface The subject site is located on the west side of Talbot Road South, just west of the intersection with South 21st Street, in Renton, Washington. The site is comprised of a single tax parcel (King County Parcel No. 722200-0175) and totals roughly 1.39 acres in area. The approximate site location is depicted on Plate 1 (Vicinity Map). Based on the Public Land Survey System (PLSS), the site is located in the southeast quarter of the southeast quarter of section 19, township 23 north, range 5 east (SE 1/4 SE 1/4 S19, T23N, R5E). Approximated site locations shown on Plates 3 through 5 (introduced in later sections of this report) are based on measurements from PLSS section lines, which are illustrated on the attached graphics. Please note that the map on Plate 4 delineates each quarter of sections 19 (SE 1/4), 20 (SW 1/4), 29 (NW 1/4), and 30 (NE 1/4) within T23N, R5E. Plates 3 and 5 do not illustrate section quarters, but instead only depict section boundaries with respect to the PLSS. The site is currently developed with a single-family residence, outbuildings, and associated improvements. Undeveloped portions of the site are primarily surfaced with grasses and landscaping areas. Surface topography descends from east to west at gentle gradients, with an estimated 30 to 35 feet of total vertical relief across the site. The site is bordered to the north and south by existing residential development, to the east by Talbot Road South, and to the west by Shattuck Avenue South. Subsurface An ESNW representative observed, logged, and sampled five borings between May 15 and May 17, advanced at accessible locations within the property boundaries using a track-mounted mud- rotary drill rig and operators retained by ESNW. The subsurface exploration locations were selected to avoid existing improvements and utility lines and based on historical coal mine mapping (described later in this report) in areas most probable to encounter historical mine workings. The purpose of the subsurface exploration was to assess and classify the site soils, to characterize the groundwater conditions within areas proposed for new development, and to evaluate the risk of surface subsidence (and other hazards) due to suspected historical coal mine workings near the subject site. The soil borings were advanced to a maximum depth of about 80 feet bgs, and all explorations were terminated within undisturbed, competent Renton Formation bedrock. The approximate locations of the borings are depicted on Plate 2 (Boring Location Plan). Please refer to the exploration logs provided in Appendix A for a more detailed description of subsurface conditions. Representative soil samples collected at our exploration sites were analyzed in general accordance with Unified Soil Classification System (USCS) and USDA methods and procedures. DocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C Seattle LLL, LLC ES-9099 July 18, 2023 Page 4 Earth Solutions NW, LLC Topsoil and Fill Topsoil thickness was not directly observed during the subsurface exploration. Sampling methods employed during mud-rotary drilling typically bypass surficial topsoil layers, and the shallowest samples were collected at five feet bgs across the site during the exploration. In any case, based on our experience in the project vicinity, typical topsoil sections range in thickness from about 6 inches up to about 18 inches. It is possible that deeper or shallower pockets of topsoil are present in localized areas across the site. Thickness of the topsoil layer is heavily influenced historical site activities such as previous development, site grading, or agricultural practices. Topsoil can commonly be characterized by its dark brown color, the presence of fine organic material, and small root intrusions. Fill was not encountered at the exploration locations. Fill may be present in isolated areas of the site, such as the “dirt mounds” indicated on the referenced feasibility layout in the western site portion, or in areas surrounding existing site improvements and utilities. However, deep (i.e., greater than five feet thick), widespread fills were not observed during the subsurface exploration and are not expected to be present at the subject site. Native Soil In general, geologic stratigraphy can be characterized as glacial till deposits atop Renton Formation siltstone and sandstone bedrock. Thickness of the glacial till deposit varied from about 8 feet in the western portion of the site near Shattuck Avenue South, up to about 30 feet in the eastern portion near Talbot Road South. Visual and laboratory classifications of the samples collected from the glacial till deposits characterized the soils primarily as silty sand (USCS: SM) with minor amounts of scattered gravel. The native soils frequently exhibited zones of light iron oxide staining and weak cementation, which are typical of glacial till deposits. Blow counts recorded during the exploratory drilling indicate the glacial till is chiefly in a very dense condition (i.e., N>50), with isolated areas of medium dense to dense near surface deposits (i.e., at B-3, B-4, and B-5, within five feet of the existing ground surface). Based on the laboratory analyses, the silty sands contain considerable fines between about 42 and 49 percent. At boring B-2, the surficial soils were classified as a sandy silt, with fines contents of up to about 58 percent. Soil moisture was characterized as moist to wet, and moisture content typically ranged between about 10 and 20 percent. Bedrock Renton Formation bedrock was encountered at all five boring locations, and all borings were terminated within very dense, undisturbed bedrock deposits. As noted above, depth to bedrock varied from about 8 feet in the western portion of the site near Shattuck Avenue South, up to about 30 feet in the eastern portion near Talbot Road South. The observed bedrock was visually classified to include both sandstone and siltstone members of the Renton Formation. Trace to minor amounts of coal, present in millimeter-scale laminations or as sand-sized clasts, was observed throughout the explored bedrock strata and at variable depths. DocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C Seattle LLL, LLC ES-9099 July 18, 2023 Page 5 Earth Solutions NW, LLC Relevant geotechnical descriptors were taken from the referenced WSDOT Geotechnical Design Manual and incorporated into the characterization of bedrock encountered during the investigation. As such, the sandstone member was primarily characterized as light gray (N7), medium to coarse grained, fresh (Grade I), very weak to moderately weak rock (R1 to R2), with isolated areas in the upper part of the formation characterized as moderate yellowish brown (10YR 6/6) and slightly weathered (Grade II). Similarly, the deeper siltstone member was characterized primarily as very dense, moist, light gray (N7), fine grained, fresh (Grade I), extremely to very weak rock (R0 to R1). N-values recorded throughout the bedrock profile observed during the exploration correlate to very dense deposits (i.e., N>50). At all boring locations, sandstone was the first rock type encountered beneath the glacial till cap. The sandstone member extended to the termination depth of borings B-3 and B-5. Underlying the sandstone and extending to the termination depth of borings B-1, B-2, and B-4, siltstone was encountered at depths of roughly 58 feet, 25 feet, and 40 feet, respectively. The sandstone member was encountered in a relatively weathered condition at borings B-1 and B-2, becoming unweathered and gray at depths between roughly 25 and 30 feet. At borings B-3 through B-5, unweathered sandstone was encountered at the upper bedrock surface and extended to the termination depth or the contact with the underlying siltstone. In general, the upper sandstone member was easily friable within the sample spoons, lacking strong cementation and a fine-grained cohesive matrix. Siltstones encountered across the site were in a relatively unweathered condition throughout the observed geologic profiles. In general, drilling through the sedimentary rocks was relatively slow, and the drill rig exhibited consistent drilling behavior indicating relatively uniform conditions and a lack of void spaces (such as an abandoned coal mine tunnel). We utilized two different drilling bits within the bedrock units: a tricone bit (standard bit for mud-rotary in the Puget Sound) was utilized to penetrate the upper glacial till and sandstone bedrock strata where the probability of encountering gravel clasts was higher (tricones are more durable through gravels). Once the boreholes were advanced through the till and upper sandstone members, the drill rig was retooled with a drag bit, providing increased drilling efficiency through the relatively dense and fine-grained lower sandstone and siltstone members. Evidence of both primary and secondary bedrock structures were observed within the collected samples. Bedding was evidenced in both silt- and sandstone members by the presence of millimeter-scale laminations, although some sections of bedrock were “massively” bedded (i.e., no bedding). Direct measurements of structural attitude and bedding orientation were not possible; however, it should be noted that the observed laminations described above were in a near-vertical orientation relative to the sampling spoon, indicating that sedimentary bedding within the Renton Formation beneath the subject site dips at high angles relative to horizontal. Geologic Setting Geologic mapping of the area indicates the site is underlain primarily by Vashon-age ground moraine (Qgt) deposits. Along the western property line and parallel with Shattuck Avenue South, Renton Formation bedrock (Tr) is identified and extends west to the Green River valley floor. The geologic map also depicts the presence of the Talbot Syncline just north of the subject site. A portion of the referenced geologic map is included on Plate 3 of this report. DocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C Seattle LLL, LLC ES-9099 July 18, 2023 Page 6 Earth Solutions NW, LLC Ground moraine deposits are synonymous with glacial till deposits and are locally divided into “lodgment till” and “ablation till.” Lodgment till generally consists of a compact and unsorted mixture of gravel, sand, silt, and clay that is commonly referred to as “hardpan.” Ablation till is similar but is typically much less compact and coherent. Renton Formation bedrock is characterized as arkosic sandstone, mudstone, and shale containing coal beds mostly near the base or middle of the formation. Renton Formation bedrock is also characterized by its numerous faults of small displacement and wavy bedding. A syncline is a fold or “trough” in which initially horizontal and planar geologic strata are deformed into concave upward geometry by compressional tectonic stresses. The fold axis, or the centerline of the fold, crosscuts immediately north of the subject property in an east-southeast, west-northwest orientation. A detailed characterization of regional geology is available in the referenced Geological Survey professional paper. The online WSS resource identifies Beausite gravelly sandy loam on 6 to 15 percent slopes (Map Unit Symbol: BeC) as the primary soil unit underlying the site. Beausite soils formed in glacial deposits underlain by sandstone at depth, and support vegetation including alder, fir, cedar, and associated brush and shrubs. Per the referenced USDA soil survey, the native soils are characterized with medium surface water runoff and moderate hazard of water erosion. In our opinion, the site geology and soil conditions are consistent with the published resources outlined in this section. Groundwater Groundwater was not observed at the boring locations primarily due to the pressurized injection of drilling fluids utilized in mud-rotary drilling techniques, which inherently obscures the observation of natural groundwater. However, based on the conditions encountered, in our opinion, significant quantities of groundwater are unlikely to be present at the subject site. If encountered, groundwater flow rates would be expected to be relatively light. It should be noted that zones of perched groundwater seepage are common within glacial deposits, particularly along sections of sloping topography, and groundwater seeps should be expected within site excavations at depth. Groundwater seepage rates and elevations may fluctuate depending on many factors, including precipitation duration and intensity, the time of year, and soil conditions. In general, groundwater flow rates are higher during the winter, spring, and early summer months. Geologic Critical Areas Review ESNW reviewed Title IV, Chapter 3, Section 4-3-050 – Critical Areas Regulations – of the Renton Municipal Code (RMC) to assess the presence of geologic critical areas at the subject site. ESNW also reviewed the City of Renton’s online GIS “COR” mapping resource, which depicts suspected critical areas throughout the jurisdiction. Regulated geologic critical areas within the City of Renton (City) include steep slopes, landslide hazards, erosion hazards, seismic hazards, and coal mine hazards. DocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C Seattle LLL, LLC ES-9099 July 18, 2023 Page 7 Earth Solutions NW, LLC Based on our review, the critical areas mapping indicates a moderate coal mine hazard area is present at the subject site. High and moderate landslide hazard areas are also indicated just off the northwest property corner, and isolated areas of “regulated slopes” are mapped around the site perimeters, most notably along the eastern property line. However, slope heights within areas identified as regulated slopes are limited to about five feet maximum per the COR map resource, and slope gradients are below the threshold to be classified as either “sensitive” or “protected” slopes. Coal Mine Hazard The subject site falls entirely within an area identified as a moderate/medium coal mine hazard area per City of Renton GIS mapping. Moderate/medium coal mine hazards are defined in the RMC as: areas where mine workings are deeper than two hundred feet (200’) for steeply dipping seams, or deeper than fifteen (15) times the thickness of the seam or workings for gently dipping seams. These areas may be affected by subsidence. Historical mine mapping available through Washington State DNR’s online Geologic Information Portal indicates the subject site is bordered on both north and south sides by abandoned underground coal mines, including the Old Patton and Sunbeam mines. We selected one map (Coal Mine Map K32 A) from the DNR catalogue to include on Plate 4 of this report. In our opinion, Map K32 A effectively and representatively illustrates the approximate site location and surrounding historical coal mining activity. Based on the historical mapping reviewed, it appears that mine entrances for the Sunbeam Mine (south of the subject site) were opened along the lower portion of the eastern Green River valley wall at elevations between roughly 50 and 65 feet. Records of the Old Patton Mine (north of the subject site) are significantly less detailed than those of the Sunbeam mine; however, it is presumed that mine entrances for the Old Patton Mine were opened in a similar fashion along the eastern Green River valley wall. Notably, the fold axis of the Talbot Syncline (also named the Patton Syncline), which crosscuts the region in an east-southeast, west-northwest orientation, separates the Sunbeam and Old Patton mines. Assuming the Talbot Syncline has relatively symmetrical fold geometry (and the axial plane is relatively vertical), historical mine workings for the Old Patton mine are likely at comparable elevations to those for the Sunbeam mine, as both mines are roughly equidistant from the fold axis. Based on topographic information available through the COR mapping resource, surface elevations at the subject site range from roughly 166 feet in the northwest site corner to about 198 feet along the eastern property line. As depicted on the historical DNR coal mine maps, mined-out areas within the Sunbeam Mine were surveyed at roughly elevation 69 feet. As such, we would expect that historical coal mine workings would be at least 97 to 129 feet bgs assuming horizontal geologic stratigraphy. However, per the geologic map, the Renton Formation stratigraphy underlying the subject site and surrounding area are deformed into concave upward geometry (a syncline). Based on our subsurface observations and structural measurements on the geologic map, strata within the Renton Formation beneath the subject site dip at steep angles towards the north. Per the historical coal mine mapping, dip angles within the mining zone of the Sunbeam Mine are documented between 55 and 65 degrees to the north. DocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C Seattle LLL, LLC ES-9099 July 18, 2023 Page 8 Earth Solutions NW, LLC As such, given the synclinal fold geometry and the relative location of the subject site roughly 200 to 500 feet north (down dip) of mapped, known mine workings, the coal seam targeted by the nearby mining operations is expected to be deepest along the fold axis. Therefore, we would expect that if mining operations had progressed directly beneath the subject site, the abandoned workings would be deeper than the estimated elevations of coal mine workings assuming horizontal stratigraphy above (i.e., 97 to 129 feet bgs), as the mining operation would have been advanced down dip and at progressively lower elevations approaching the fold axis. Readily available LiDAR mapping of the subject site reveals potential mining related disturbances west of the site – apparent fill deposits and roadcuts are present on the eastern Green River valley wall near the Sunbeam Mine entrance, and consistent with the depiction of historical mine workings shown on the historical coal mine maps. However, mining related disturbances and evidence of surface subsidence are not visible within the site boundaries on the LiDAR mapping. A LiDAR-based shaded relief map of the subject site is included on Plate 5. Geologic stratigraphy observed at the boring locations was generally characterized as about 8 to 30 feet of glacial till deposits atop competent Renton Formation sandstone and siltstone bedrock. Undisturbed Renton Formation bedrock extended to the termination depth of all five borings advanced across the property, and no evidence of open voids, loose or collapsed coal mine workings, or thick coal seams was observed within any of the boreholes. Historical mine maps do not illustrate mined-out areas directly beneath the subject site. However, based on the COR mapping of moderate/medium coal mine hazard areas encompassing the subject site, undocumented mining may have occurred. The subsurface explorations were advanced to a maximum depth of about 80 feet bgs, and as such, we are unable to conclusively rule out the presence of abandoned mine workings within the upper 200 feet of existing grades. In consideration of the evidence and reasoning outlined above, however, it is our opinion that the site can be classified as a low coal mine hazard. Low coal mine hazards are defined in the RMC as: areas with no known mine workings and no predicted subsidence. While no mines are known in these areas, undocumented mining is known to have occurred. In our opinion, the risk of surface subsidence due to collapsing coal mine workings may be considered very low to negligible based on the competent underlying geology and lack of coal mine related void space encountered at the exploration locations. In our opinion, coal mine hazard area regulations and specialized design considerations regarding potential surface subsidence are not necessary for this project. Per the RMC, any hazards found during development activities shall be immediately reported to both ESNW and the Development Services Division. Any coal mine hazards shall be mitigated prior to re-commencing construction based on supplemental recommendations or reports prepared by the geotechnical professional. DocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C Seattle LLL, LLC ES-9099 July 18, 2023 Page 9 Earth Solutions NW, LLC Landslide Hazard High and moderate landslide hazard areas are indicated on the COR map resource just off the northwest property corner. However, the referenced landslide hazard area map does not depict the same hazard area. In our opinion, based on our observations of very dense glacial till and competent Renton Formation bedrock underlying the subject site and topographic data depicted on the COR map, the mapped landslide hazard area is in error. Slope gradients surrounding the site generally fall below the 15 percent threshold to be classified as high or medium landslide hazards. Low landslide hazard areas include any areas with slopes less than 15 percent. Therefore, the site and immediately surrounding area can be classified as a low landslide hazard area. In our opinion, the risk of landsliding as a result of existing and/or proposed site development activities should be considered very low to negligible on account of the very dense and competent underlying geology. DISCUSSION AND RECOMMENDATIONS General Based on the results of our investigation, the proposed residential construction is feasible from a geotechnical standpoint. The primary geotechnical considerations associated with the proposed project include earthwork, temporary excavations, structural fill requirements, subgrade preparation, retaining wall foundation support, slab-on-grade support, utility support and trench backfill, drainage, and stormwater management. Geologic stratigraphy observed at the subsurface exploration locations generally consisted of about 8 to 30 feet of native glacial till deposits atop competent Renton Formation sandstone and siltstone bedrock, which extended to the maximum exploration depth of about 80 feet below existing grades and to the termination depth of all exploratory borings. The subject site falls entirely within an area identified as a moderate/medium coal mine hazard area per City of Renton GIS mapping. However, based on the results of our investigation, the site can be classified as a low coal mine hazard area. In our opinion, the risk of surface subsidence due to collapsing coal mine workings may be considered very low to negligible based on the competent underlying geology and lack of coal mine related void space encountered at the exploration locations. In our opinion, coal mine hazard area regulations and specialized design considerations regarding potential surface subsidence are not necessary for this project. As such, the typical residential structure proposed to be constructed on this site can be supported on conventional spread and continuous foundations bearing on undisturbed competent native soil, recompacted native soil, or new structural fill placed directly on a competent subgrade. Competent native soil suitable for foundation support is expected to be encountered beginning at depths of about two to three feet below existing grades across the site. DocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C Seattle LLL, LLC ES-9099 July 18, 2023 Page 10 Earth Solutions NW, LLC The native glacial till and underlying bedrock deposits exhibit very poor infiltration characteristics, including high relative density, high fines content, and weak cementation. In our opinion, full infiltration should be considered infeasible from a geotechnical standpoint. This study has been prepared for the exclusive use of Seattle LLL, LLC, and its representatives. A warranty is neither expressed nor implied. This study has been prepared in a manner consistent with the level of care and skill ordinarily exercised by other members of the profession currently practicing under similar conditions in this area. Site Preparation and Earthwork Site preparation activities should consist of installing temporary erosion control measures and performing site stripping within the designated clearing limits. Subsequent earthwork activities may involve additional grading and utility installations. Temporary Erosion Control The following temporary erosion and sediment control (TESC) Best Management Practices (BMPs) should be considered:  Temporary construction entrances and drive lanes, consisting of at least six inches of quarry spalls, should be considered to both minimize off-site soil tracking and provide stable surfaces at site entrances. Placing geotextile fabric underneath the quarry spalls will provide greater stability, if needed.  Silt fencing should be placed around the appropriate portions of the site perimeter.  When not in use, soil stockpiles should be covered or otherwise protected to reduce the potential for soil erosion, especially during periods of wet weather.  Temporary measures for controlling surface water runoff, such as interceptor trenches, sumps, or interceptor swales, should be installed prior to beginning earthwork activities.  Dry soils disturbed during construction should be wetted to minimize dust and airborne soil erosion. Additional TESC BMPs, as specified by the project civil engineer and indicated on the plans, should be incorporated into construction activities. TESC BMPs may be modified during construction as site conditions require and as approved by the site erosion control lead. Excavations and Slopes Based on the soil conditions observed at the exploration locations, excavation activities are likely to expose medium dense to dense native soils within the upper five feet of existing grades, transitioning to very dense, cemented, and competent glacial till or native Renton Formation bedrock at depth. The presence of shallow perched groundwater seepage should be anticipated within site excavations. DocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C Seattle LLL, LLC ES-9099 July 18, 2023 Page 11 Earth Solutions NW, LLC The following Federal Occupation Safety and Health Administration and Washington Industrial Safety and Health Act soil classifications and maximum allowable temporary slope inclinations may be used:  Areas exposing groundwater seepage 1.5H:1V (Type C)  Loose soil and fill 1.5H:1V (Type C)  Medium dense to dense soil 1H:1V (Type B)  Dense to very dense native soil or bedrock 0.75H:1V (Type A) Groundwater seepage should be anticipated during excavation activities, particularly if excavations take place during the wet season. An ESNW representative should observe temporary excavations to evaluate the presence of groundwater seepage. If seepage is not observed, steeper temporary slope inclinations may be feasible, particularly where the native, unweathered, and cemented “hardpan” glacial till deposits are exposed within relatively large, open excavations. As previously noted, coal mine related hazards found during development activities shall be immediately reported to both ESNW and the Development Services Division for remediation. An ESNW representative should observe temporary and permanent slopes to confirm the slope inclinations are suitable for the exposed soil conditions and to provide additional excavation and slope recommendations, as necessary. If the recommended temporary slope inclinations cannot be achieved, temporary shoring may be necessary to support excavations. Permanent slopes should be planted with vegetation to both enhance stability and minimize erosion and should maintain a gradient of 2H:1V or flatter. Structural Fill Structural fill is defined as compacted soil placed in foundation, slab-on-grade, roadway, permanent slope, retaining wall, and utility trench backfill areas. Structural fill placed and compacted during site grading activities should meet the following specifications and guidelines:  Structural fill material Granular soil  Moisture Content At or slightly above optimum  Relative compaction (minimum) 95 percent (Modified Proctor)  Loose lift thickness (maximum) 12 inches The in-situ mineral soils may not be suitable for use as structural fill unless the soil is at (or slightly above) the optimum moisture content at the time of placement and compaction. Soil shall not be placed dry of the optimum moisture content and should be evaluated by ESNW during construction. DocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C Seattle LLL, LLC ES-9099 July 18, 2023 Page 12 Earth Solutions NW, LLC If native soil is placed below the optimum moisture content, settlement will likely occur during periods of wet weather. As such, structural fill soils should be properly moisture conditioned, as necessary, to ensure acceptability of the soil moisture content at the time of placement and compaction. Native soil will be difficult or impossible to use as structural fill during extended wet weather conditions. In this respect, moisture conditioning or treatment of the soils may be necessary at some locations prior to use as structural fill. With respect to underground utility installations and backfill, local jurisdictions may dictate the soil type(s) and compaction requirements. Unsuitable material or debris must be removed from structural areas if encountered. In-situ and Imported Soil The in-situ soils encountered at the subject site have a high sensitivity to moisture and were generally in a moist to wet condition at the time of exploration. Soils anticipated to be exposed on site will degrade rapidly if exposed to wet weather and construction traffic. Compaction of the soil to the levels necessary for use as structural fill may be difficult or impossible during wet weather conditions, and are likely to be over the optimum moisture content immediately after excavation. Soils encountered during site excavations that are excessively over the optimum moisture content will likely require aeration or treatment prior to placement and compaction. Conversely, soils that are substantially below the optimum moisture content will require moisture conditioning through the addition of water prior to use as structural fill. An ESNW representative should be contacted to evaluate the suitability of the in-situ soil for use as structural fill at the time of construction. Imported soil intended for use as structural fill should be evaluated by ESNW during construction. The imported soil must be workable to the optimum moisture content, as determined by the Modified Proctor Method (ASTM D1557), at the time of placement and compaction. During wet weather conditions, imported soil intended for use as structural fill should consist of a well-graded, granular soil with a fines content of 5 percent or less (where the fines content is defined as the percent passing the Number 200 sieve, based on the minus three-quarter-inch fraction). Wet Season Grading Earthwork activities that occur during the wet season may require additional measures to protect both structural subgrades and soil intended for use as structural fill. Site-specific recommendations can be provided at the time of construction and may include leaving cut areas several inches above design subgrade elevations, covering working surfaces with crushed rock, protecting structural fill soil from adverse moisture conditions, and additional TESC recommendations. ESNW can assist in obtaining a wet season grading permit if required by the governing jurisdiction. DocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C Seattle LLL, LLC ES-9099 July 18, 2023 Page 13 Earth Solutions NW, LLC Subgrade Preparation Following site stripping, ESNW should be contacted to observe the subgrade to confirm soil conditions are as anticipated and to provide supplementary recommendations for subgrade preparation, as necessary. Such supplementary recommendations for subgrade improvement may be provided at the time of construction and would likely include further mechanical compaction or overexcavation and replacement with suitable structural fill. Void Space Restoration The process of removing the existing structures may produce voids where old foundations are removed and where crawl space areas may have been present. Complete restoration of voids from old foundation areas must be executed as part of the subgrade preparation activities. The following guidelines for preparing the subgrade where existing structures have been removed should be incorporated into the final design:  Where voids and related demolition disturbances extend below planned subgrade elevations, restoration of these areas should be completed. Structural fill should be used to restore voids or unstable areas resulting from the removal of existing structural elements.  Recompact, or overexcavate and replace, areas of existing fill exposed throughout areas of future subgrade. Overexcavations should extend into competent native soils and structural fill should be utilized to restore subgrade elevations, as necessary.  ESNW should confirm subgrade conditions, as well as the required level of re-compaction and/or overexcavation and replacement, during site preparation activities. ESNW should also evaluate the overall suitability of prepared subgrade areas following site preparation activities. Grading and Excavations in Bedrock Site grading and excavations may extend into the underlying and relatively competent sandstone bedrock. The upper surface of Renton Formation bedrock will likely be rippable with conventional equipment. However, areas of increased difficulty should be anticipated. In our opinion, the contractor should be prepared with tiger-teeth-fitted excavator buckets for excavations that extend into the sandstone bedrock, particularly in the western portion of the site where bedrock was encountered within about eight feet of the existing ground surface. ESNW would be available during initial mass grading activities to further evaluate rippability of the native bedrock with the grading contractor, if requested. Foundations Typical two- to three-story residential structures constructed on this site can be supported on conventional spread and continuous footings bearing on competent (undisturbed) native soil, recompacted native soil, or new structural fill placed directly on a competent subgrade. Provided site earthwork activities are completed in accordance with our recommendations, suitable soil conditions should be exposed beginning at depths of about two to three feet bgs. DocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C Seattle LLL, LLC ES-9099 July 18, 2023 Page 14 Earth Solutions NW, LLC An ESNW representative should be requested to confirm the suitability of foundation subgrades at the time of construction. If deemed necessary, the undisturbed native soils may be compacted in situ provided the soil is at or slightly above the optimum moisture content. Due to the high moisture sensitivity of the site soils, foundation subgrade areas should be protected from wet weather or areas of remediation should be anticipated; a layer of crushed rock can be considered to protect foundation subgrade areas. If structural building pads are disturbed during wet weather, remediation measures such as overexcavation and replacement with rock may be necessary in some areas. Provided the structure(s) will be supported as described above, the following parameters may be used for design of the new foundations:  Allowable soil bearing capacity 2,500 psf  Passive earth pressure 300 pcf  Coefficient of friction 0.40 A one-third increase in the allowable soil bearing capacity can be assumed for short-term wind and seismic loading conditions. The passive earth pressure and coefficient of friction values include a safety factor of 1.5. With structural loading as expected, total settlement in the range of one inch is anticipated, with differential settlement of about one-half inch. Most of the anticipated settlement should occur during construction as dead loads are applied. Retaining Walls Retaining walls must be designed to resist earth pressures and applicable surcharge loads. The following parameters may be used for retaining wall design:  Active earth pressure (unrestrained condition) 35 pcf  At-rest earth pressure (restrained condition) 55 pcf  Traffic surcharge (passenger vehicles) 70 psf (rectangular distribution)  Passive earth pressure 300 pcf  Coefficient of friction 0.40  Seismic surcharge 8H psf* * Where H equals the retained height (in feet). The passive earth pressure and coefficient of friction values include a safety factor of 1.5. Additional surcharge loading from adjacent foundations, sloped backfill, or other loads should be included in the retaining wall design. DocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C Seattle LLL, LLC ES-9099 July 18, 2023 Page 15 Earth Solutions NW, LLC Retaining walls should be backfilled with free-draining material that extends along the height of the wall and a distance of at least 18 inches behind the wall. The upper 12 inches of the wall backfill may consist of a less permeable soil, if desired. Drainage should be provided behind retaining walls such that hydrostatic pressures do not develop. If drainage is not provided, hydrostatic pressures should be included in the wall design. A perforated drainpipe should be placed along the base of the wall and connected to an approved discharge location. A typical retaining wall drainage detail is provided on Plate 6. Seismic Design The 2018 International Building Code (2018 IBC) recognizes the most recent edition of the Minimum Design Loads for Buildings and Other Structures manual (ASCE 7-16) for seismic design, specifically with respect to earthquake loads. Based on the soil and bedrock conditions encountered at the exploration locations, the parameters and values provided below are recommended for seismic design per the 2018 IBC. Parameter Value Site Class C* Mapped short period spectral response acceleration, SS (g) 1.427 Mapped 1-second period spectral response acceleration, S1 (g) 0.486 Short period site coefficient, Fa 1.200 Long period site coefficient, Fv 1.500 Adjusted short period spectral response acceleration, SMS (g) 1.712 Adjusted 1-second period spectral response acceleration, SM1 (g) 0.728 Design short period spectral response acceleration, SDS (g) 1.142 Design 1-second period spectral response acceleration, SD1 (g) 0.486 * Assumes very dense native soil and bedrock conditions, encountered to a maximum depth of 80 feet bgs during the May 2023 field exploration, remain very dense to at least 100 feet bgs. As indicated in the table footnote, several of the seismic design values provided above are dependent on the assumption that site-specific ground motion analysis (per Section 11.4.8 of ASCE 7-16) will not be required for the subject project. ESNW recommends the validity of this assumption be confirmed at the earliest available opportunity during the planning and early design stages of the project. Further discussion between the project structural engineer, the project owner, and ESNW may be prudent to determine the possible impacts to the structural design due to increased earthquake load requirements under the 2018 IBC. ESNW can provide additional consulting services to aid with design efforts, including supplementary geotechnical and geophysical investigation, upon request. DocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C Seattle LLL, LLC ES-9099 July 18, 2023 Page 16 Earth Solutions NW, LLC Liquefaction is a phenomenon that can occur within a soil profile as a result of an intense ground shaking or loading condition. Most commonly, liquefaction is caused by ground shaking during an earthquake. Soil profiles that are loose, cohesionless, and present below the groundwater table are most susceptible to liquefaction. During the ground shaking, the soil contracts, and porewater pressure increases. The increased porewater pressure occurs quickly and without sufficient time to dissipate, resulting in water flowing upward to the ground surface and a liquefied soil condition. Soil in a liquefied condition possesses very little shear strength in comparison to the drained condition, which can result in a loss of foundation support for structures. In our opinion, and consistent with the depiction on the referenced liquefaction susceptibility map, site susceptibility to liquefaction may be considered very low to negligible. The absence of a shallow groundwater table and the relatively dense and cemented characteristics of the native soil and bedrock were the primary bases for this opinion. Slab-on-Grade Floors Slab-on-grade floors should be supported on a firm and unyielding subgrade consisting of competent native soil or at least 12 inches of new structural fill. Unstable or yielding areas of the subgrade should be recompacted or overexcavated and replaced with suitable structural fill prior to slab construction. A capillary break consisting of a minimum of four inches of free-draining crushed rock or gravel should be placed below the slab. The free-draining material should have a fines content of 5 percent or less defined as the percent passing the number 200 sieve, based on the minus three- quarter-inch fraction. In areas where slab moisture is undesirable, installation of a vapor barrier below the slab should be considered. If used, the vapor barrier should consist of a material specifically designed to function as a vapor barrier and should be installed in accordance with the manufacturer’s specifications. Utility Support and Trench Backfill The native soils observed at the subsurface exploration locations are generally suitable for support of utilities. Utility trench excavations may encounter bedrock; see above for a discussion regarding excavations into bedrock. Use of the native soil as structural backfill in the utility trench excavations will depend on the in- situ moisture content at the time of placement and compaction. If native soil is placed below the optimum moisture content, settlement will likely occur once wet weather impacts the trenches. As such, backfill soils should be properly moisture conditioned, as necessary, to ensure acceptability of the soil moisture content at the time of placement and compaction. Native soil will be difficult or impossible to use as utility trench backfill during extended wet weather conditions. In this respect, moisture conditioning or treatment of the soils may be necessary at some locations prior to use as structural fill. Utility trench backfill should be placed and compacted to the specifications of structural fill provided in this report or to the applicable requirements of the presiding jurisdiction. DocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C Seattle LLL, LLC ES-9099 July 18, 2023 Page 17 Earth Solutions NW, LLC Preliminary Pavement Sections The performance of site pavements is largely related to the condition of the underlying subgrade. To ensure adequate pavement performance, the subgrade should be in a firm and unyielding condition when subjected to proof rolling with a loaded dump truck. Structural fill in pavement areas should be compacted to the specifications previously detailed in this report. Soft, wet, or otherwise unsuitable or yielding subgrade conditions will require remedial measures, such as overexcavation and/or placement of thick crushed rock or structural fill sections, prior to pavement. We anticipate new pavement sections will be subjected primarily to passenger vehicle traffic. For lightly loaded pavement areas subjected primarily to passenger vehicles, the following preliminary pavement sections may be considered:  A minimum of two inches of hot-mix asphalt (HMA) placed over four inches of crushed rock base (CRB).  A minimum of two inches of HMA placed over three inches of asphalt-treated base (ATB). An ESNW representative should be requested to observe subgrade conditions prior to placement of CRB or ATB. As necessary, supplemental recommendations for achieving subgrade stability and drainage can be provided. Final pavement design recommendations, including recommendations for heavy traffic areas, access roads, and frontage improvement areas, can be provided once final traffic loading has been determined. Road standards utilized by the governing jurisdiction may supersede the recommendations provided in this report. The HMA, ATB, and CRB materials should conform to WSDOT specifications. All soil base material should be compacted to a relative compaction of 95 percent, based on the laboratory maximum dry density as determined by ASTM D1557. If on-site roads are constructed with an inverted crown, additional drainage measures may be recommended to assist in maintaining road subgrade and pavement stability. Drainage Groundwater seepage will likely be encountered within site excavations depending on the time of year grading operations take place. Temporary measures to control surface water runoff and groundwater during construction would likely involve passive elements such as interceptor trenches, interceptor swales, and sumps. ESNW should be consulted during preliminary grading to identify areas of seepage and provide recommendations to reduce the potential for seepage- related instability. The contractor should be prepared to manage areas of groundwater seepage in excavations. Finish grades must be designed to direct surface drain water away from structures and slopes. Water must not be allowed to pond adjacent to structures or slopes. In our opinion, a foundation drain should be installed along building perimeter footings. A typical foundation drain detail is provided on Plate 7. DocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C Seattle LLL, LLC ES-9099 July 18, 2023 Page 18 Earth Solutions NW, LLC Infiltration Feasibility Based on conditions encountered during the fieldwork, in our opinion, full infiltration should be considered infeasible from a geotechnical standpoint. Near surface soils consisted of very dense, weakly cemented glacial till deposits with fines contents between about 42 and 58 percent. The high relative density, high fines content, and weak cementation of native glacial till soils will severely limit in-situ hydraulic conductivity. In our opinion, the native glacial till soils and underlying bedrock should be considered impermeable for design purposes. If necessary to satisfy project objectives, limited infiltration applications may be feasible within the upper weathered soil horizon. However, depending on the extent of proposed grade modifications (i.e., grade cuts and fills), the upper weathered soils are unlikely to remain in an undisturbed condition, precluding the design and implementation of shallow LID elements. ESNW would be pleased to further investigate the feasibility of shallow LID elements, upon request. Preliminary Stormwater Vault Design Based on the presence of impermeable glacial till and bedrock deposits, we anticipate a stormwater detention vault will likely be utilized for stormwater management in the western portion of the site. Vault foundations should be supported on very dense, undisturbed native soil, bedrock, or crushed rock placed on a competent subgrade surface. Based on observations made at boring location B-1 (within Tract A), vault excavations would be expected to expose dense glacial till deposits from the surface extending to roughly eight feet bgs. Deeper than eight feet, vault excavations will likely expose slightly weathered, competent Renton Formation sandstone bedrock. Minor perched groundwater seepage may be exposed depending on the time of year excavations occur. Storm vault designs must incorporate adequate buffer space from property boundaries such that temporary excavations to construct the vault structure can be successfully completed. Perimeter drains should be installed around the vault and conveyed to an approved discharge point. The presence of perched groundwater seepage should be anticipated during excavation activities for the vault; however, buoyancy is not expected to influence the vault design. In general, and in anticipation for groundwater seepage to be present within the vault excavation, Type A and C soils (as described in the Excavations and Slopes section of this report) should be expected. DocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C Seattle LLL, LLC ES-9099 July 18, 2023 Page 19 Earth Solutions NW, LLC The following parameters can be used for stormwater vault design:  Allowable soil bearing capacity 5,000 psf (very dense glacial till or competent Renton Formation Bedrock)  Active earth pressure (unrestrained) 35 pcf  Active earth pressure (unrestrained, hydrostatic) 80 pcf  At-rest earth pressure (restrained) 55 pcf  At-rest earth pressure (restrained, hydrostatic) 100 pcf  Coefficient of friction 0.40  Passive earth pressure 350 pcf  Seismic surcharge 8H psf* * Where H equals the retained height. The passive earth pressure and coefficient of friction values include a safety factor of 1.5. The vault walls should be backfilled with free-draining material or suitable common earth if a sheet drain material is used. The upper one foot of the wall backfill can consist of a less permeable soil, if desired. A perforated drainpipe should be placed along the base of the wall and connected to an approved discharge location. If the elevation of the vault bottom is such that gravity flow to an outlet is not possible, the portion of the vault below the drain should be designed to include hydrostatic pressure. Design values accounting for hydrostatic pressure are included above. ESNW should observe grading operations for the vault and the subgrade conditions prior to concrete forming and pouring to confirm conditions are as anticipated, and to provide supplemental recommendations as necessary. Additionally, ESNW should be contacted to review final vault designs to confirm that appropriate geotechnical parameters have been incorporated into the design. We anticipate native soil will be used as vault backfill. Detention vault backfill should conform to the specifications of structural fill previously detailed in this report. The native soil is moisture sensitive and will settle once impacted by wet weather if placed below the optimum moisture content. ESNW recommends placing the native soil at or slightly above the optimum moisture content. Native soil placed substantially above the optimum moisture content will require additional time or remediation prior to supporting a structure. DocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C Seattle LLL, LLC ES-9099 July 18, 2023 Page 20 Earth Solutions NW, LLC LIMITATIONS This study has been prepared for the exclusive use of Seattle LLL, LLC, and its representatives. The recommendations and conclusions provided in this study are professional opinions consistent with the level of care and skill that is typical of other members in the profession currently practicing under similar conditions in this area. A warranty is neither expressed nor implied. Variations in the soil and groundwater conditions observed at the exploration locations may exist and may not become evident until construction. ESNW should reevaluate the conclusions provided in this study if variations are encountered. Additional Services ESNW should have an opportunity to review final project plans with respect to the geotechnical recommendations provided in this report. ESNW should also be retained to provide testing and consultation services as needed during design and construction phases of the project. DocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C Geotechnical Engineering,Construction Observation/Testing and Environmental Services Drawn MRS Checked BCS Date June 2023 Date 06/07/2023 Proj.No.9099 Plate 1 Earth Solutions NWLLCEarthSolutionsNWLLC EarthSolutions NW LLC Vicinity Map Talbot Road Property Renton,Washington Reference: King County,Washington OpenStreetMap.org NORTH NOTE:This plate may contain areas of color.ESNW cannot be responsible for any subsequent misinterpretation of the information resulting from black &white reproductions of this plate. SITE Renton DocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C Plate Proj.No. Date Checked DrawnEarthSolutionsNWLLC GeotechnicalEngineering,ConstructionObservation/TestingandEnvironmentalServicesEarthSolutionsNWLLCEarthSolutionsNWLLCBoringLocationPlanTalbotRoadPropertyRenton,WashingtonNORTHLEGEND Approximate Location of ESNW Boring,Proj.No. ES-9099,May 2023 Subject Site Existing Building Proposed Lot Number NOTE:This plate may contain areas of color.ESNW cannot be responsible for any subsequent misinterpretation of the information resulting from black &white reproductions of this plate. NOTE:The graphics shown on this plate are not intended for design purposes or precise scale measurements,but only to illustrate the approximate test locations relative to the approximate locations of existing and /or proposed site features.The information illustrated is largely based on data provided by the client at the time of our study.ESNW cannot be responsible for subsequent design changes or interpretation of the data by others. 0 2 5 5 0 1 0 0 Sc ale in Feet1"=5 0 ' MRS BCS 06/15/2023 9099 2 B-1 1 B-2 B-3 B-4 B-5 B-1 TALBOT ROAD S.TALBOT ROAD S.1 2 3 4 5 6 Tract A 170 180 190170 180 190SHATTUCK AVENUE S.DocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C Plate Proj.No. Date Checked DrawnEarthSolutionsNWLLC GeotechnicalEngineering,ConstructionObservation/TestingandEnvironmentalServicesEarthSolutionsNWLLCEarthSolutionsNWLLCCAM BCS 06/15/2023 9099 3 Reference: Geologic Map of The Renton Quadrangle, King County,Washington By D.R.Mullineaux 1965 GeologicMapTalbotRoadPropertyRenton,WashingtonNORTH NOTE:This plate may contain areas of color.ESNW cannot be responsible for any subsequent misinterpretation of the information resulting from black &white reproductions of this plate. Approximate Site Location DocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C Plate Proj.No. Date Checked DrawnEarthSolutionsNWLLC GeotechnicalEngineering,ConstructionObservation/TestingandEnvironmentalServicesEarthSolutionsNWLLCEarthSolutionsNWLLCCAM BCS 06/15/2023 9099 4 Reference: Geologic Structure Map of Renton Coal Mine, Renton Coal Company,Renton,Washington. Washington Department of Natural Resources, Historical Coal Mine Map K32 A HistoricalCoalMineMapK32ATalbotRoadPropertyRenton,WashingtonNORTH NOTE:This plate may contain areas of color.ESNW cannot be responsible for any subsequent misinterpretation of the information resulting from black &white reproductions of this plate. Approximate Site Location DocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C Geotechnical Engineering,Construction Observation/Testing and Environmental Services Drawn CAM Checked BCS Date June 2023 Date 06/15/2023 Proj.No.9099 Plate 5 Earth Solutions NWLLCEarthSolutionsNWLLC EarthSolutions NW LLC Approximate Site LocationPotentialMining Related Disturbances NOTE:This plate may contain areas of color.ESNW cannot be responsible for any subsequent misinterpretation of the information resulting from black &white reproductions of this plate. NORTH LiDAR-Based Shaded Relief Map Talbot Road Property Renton,Washington DocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C Geotechnical Engineering,Construction Observation/Testing and Environmental Services Drawn MRS Checked BCS Date June 2023 Date 06/15/2023 Proj.No.9099 Plate 6 Earth Solutions NWLLCEarthSolutionsNWLLC EarthSolutions NW LLC NOTES: Free-draining Backfill should consist of soil having less than 5 percent fines. Percent passing No.4 sieve should be 25 to 75 percent. Sheet Drain may be feasible in lieu of Free-draining Backfill,per ESNW recommendations. Drain Pipe should consist of perforated, rigid PVC Pipe surrounded with 1-inch Drain Rock. LEGEND: Free-draining Structural Backfill 1-inch Drain Rock 18"Min. Structural Fill Perforated Rigid Drain Pipe (Surround in Drain Rock) SCHEMATIC ONLY -NOT TO SCALE NOT A CONSTRUCTION DRAW ING Retaining Wall Drainage Detail Talbot Road Property Renton,Washington DocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C Geotechnical Engineering,Construction Observation/Testing and Environmental Services Drawn MRS Checked BCS Date June 2023 Date 06/15/2023 Proj.No.9099 Plate 7 Earth Solutions NWLLCEarthSolutionsNWLLC EarthSolutions NW LLC Slope Perforated Rigid Drain Pipe (Surround in Drain Rock) 18"Min. NOTES: Do NOT tie roof downspouts to Footing Drain. Surface Seal to consist of 12"of less permeable,suitable soil.Slope away from building. LEGEND: Surface Seal:native soil or other low-permeability material. 1-inch Drain Rock SCHEMATIC ONLY -NOT TO SCALE NOT A CONSTRUCTION DRAW ING Footing Drain Detail Talbot Road Property Renton,Washington DocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C Earth Solutions NW, LLC Appendix A Subsurface Exploration Logs ES-9099 Subsurface conditions on site were explored between May 15 and May 17, 2023, by advancing five borings using a track-mounted mud-rotary drill rig and operators retained by ESNW. The approximate locations of the exploration sites are illustrated on Plate 2 of this study. The exploration logs are provided in this Appendix. The borings were advanced to a maximum depth of about 80 feet bgs. The final logs represent the interpretations of the field logs and the results of laboratory analyses. The stratification lines on the logs represent the approximate boundaries between soil types. In actuality, the transitions may be more gradual. DocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C >12%Fines<5%FinesHighlyOrganicSoilsSiltsandClaysLiquidLimit50orMoreSiltsandClaysLiquidLimitLessThan50Fine-GrainedSoils-50%orMorePassesNo.200SieveCoarse-GrainedSoils-MoreThan50%RetainedonNo.200SieveSands-50%orMoreofCoarseFractionPassesNo.4SieveGravels-MoreThan50%ofCoarseFractionRetainedonNo.4Sieve>12%Fines<5%FinesGW GP GM GC SW SP SM SC ML CL OL MH CH OH PT Well-graded gravel with or without sand,little to no fines Poorly graded gravel with or without sand,little to no fines Silty gravel with or without sand Clayey gravel with or without sand Well-graded sand with or without gravel,little to no fines Poorly graded sand with or without gravel,little to no fines Silty sand with or without gravel Clayey sand with or without gravel Silt with or without sand or gravel;sandy or gravelly silt Clay of low to medium plasticity;lean clay with or without sand or gravel; sandy or gravelly lean clay Organic clay or silt of low plasticity Elastic silt with or without sand or gravel;sandy or gravelly elastic silt Clay of high plasticity; fat clay with or without sand or gravel;sandy or gravelly fat clay Organic clay or silt of medium to high plasticity Peat,muck,and other highly organic soils EEaarrtthh SSoolluuttiioonnss NNWW LLC Geotechnical Engineering,Construction Observation/Testing and Environmental Services EXPLORATION LOG KEYFillFILLMadeGround Classifications of soils in this geotechnical report and as shown on the exploration logs are based on visual field and/or laboratory observations,which include density/consistency,moisture condition,grain size,and plasticity estimates,and should not be construed to imply field or laboratory testing unless presented herein. Visual-manual and/or laboratory classification methods of ASTM D2487 and D2488 were used as an identification guide for the Unified Soil Classification System. Terms Describing Relative Density and Consistency Coarse-Grained Soils: Fine-Grained Soils: SPT blows/foot SPT blows/foot Test Symbols &Units Fines =Fines Content (%) MC =Moisture Content (%) DD =Dry Density (pcf) Str =Shear Strength (tsf) PID =Photoionization Detector (ppm) OC =Organic Content (%) CEC =Cation Exchange Capacity (meq/100 g) LL =Liquid Limit (%) PL =Plastic Limit (%) PI =Plasticity Index (%) Component Definitions Descriptive Term Size Range and Sieve Number Smaller than No.200 (0.075 mm) Boulders Modifier Definitions Percentage by Weight (Approx.) <5 5 to 14 15 to 29 >30_ Modifier Trace (sand,silt,clay,gravel) Slightly (sandy,silty,clayey,gravelly) Sandy,silty,clayey,gravelly Very (sandy,silty,clayey,gravelly) Moisture Content Dry -Absence of moisture,dusty,dry to the touch Damp -Perceptible moisture,likely below optimum MC Moist -Damp but no visible water,likely at/near optimum MC Wet -Water visible but not free draining, likely above optimum MC Saturated/Water Bearing -Visible free water,typically below groundwater table Symbols Cement grout surface seal Bentonite chips Grout seal Filter pack with blank casing section Screened casing or Hydrotip with filter pack End cap ATD =At time of drilling Static water level (date) _>50 Density Very Loose Loose Medium Dense Dense Very Dense Consistency Very Soft Soft Medium Stiff Stiff Very Stiff Hard <4 4 to 9 10 to 29 30 to 49 <2 2 to 3 4 to 7 8 to 14 15 to 29 _>30 EEaarrtthh NNWWLLC EarthSolutions NW LLC Cobbles Gravel Coarse Gravel Fine Gravel Sand Coarse Sand Medium Sand Fine Sand Silt and Clay Larger than 12" 3"to 12" 3"to No.4 (4.75 mm) 3"to 3/4" 3/4"to No.4 (4.75 mm) No.4 (4.75 mm)to No.200 (0.075 mm) No.4 (4.75 mm)to No.10 (2.00 mm) No.10 (2.00 mm)to No.40 (0.425 mm) No.40 (0.425 mm)to No.200 (0.075 mm) DocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C 165.0 SS SS 100 100 15-22-26 (48) 11-20-24 (44) MC = 13.4 Fines = 49.2 MC = 20.0 SM Bedrock Gray silty SAND, dense, moist [USDA Classification: slightly gravelly LOAM] -light iron oxide staining -minor scattered fine gravel -machine chatter SANDSTONE (Renton Formation Bedrock), moderate yellowish brown (10YR 6/6), medium to coarse grained, slightly weathered (Grade II), very weak to moderately weak rock (R1 to R2) -heavily oxidized to about 30' -mm scale laminations -poorly graded medium to coarse sand grains with silty matrix 8.0DEPTH(ft)0.0 2.5 5.0 7.5 10.0 12.5 15.0 (Continued Next Page)SAMPLE TYPENUMBERDRILLING CONTRACTOR Holocene Drilling DATE STARTED 5/15/23 COMPLETED 5/15/23 GROUND WATER LEVEL: GROUND ELEVATION 173 ft LATITUDE 47.46082 LONGITUDE -122.21248 LOGGED BY BCS CHECKED BY HTW NOTES SURFACE CONDITIONS Field grass AT TIME OF DRILLINGAT TIME OF DRILLING AFTER DRILLING PAGE 1 OF 6 BORING NUMBER B-1 PROJECT NUMBER ES-9099 PROJECT NAME Talbot Road Property GENERAL BH / TP / WELL - 9099.GPJ - GINT US.GDT - 7/18/23Earth Solutions NW, LLC 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 RECOVERY %BLOWCOUNTS(N VALUE)TESTS U.S.C.S.MATERIAL DESCRIPTION GRAPHICLOGDocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C 143.0 SS SS SS 100 100 100 17-50/5" 22-22-32 (54) 50/6" MC = 16.6 MC = 19.5 MC = 19.5 Bedrock SANDSTONE (Renton Formation Bedrock), moderate yellowish brown (10YR 6/6), medium to coarse grained, slightly weathered (Grade II), very weak to moderately weak rock (R1 to R2) (continued) -smooth, consistent rig behavior to BOH -becomes moderate yellowish brown (10YR 6/6) and light gray (N7) -trace coal present in mm scale laminations and sand-sized clasts -trace coal present in mm scale laminations 30.0DEPTH(ft)15.0 17.5 20.0 22.5 25.0 27.5 30.0 (Continued Next Page)SAMPLE TYPENUMBERDRILLING CONTRACTOR Holocene Drilling DATE STARTED 5/15/23 COMPLETED 5/15/23 GROUND WATER LEVEL: GROUND ELEVATION 173 ft LATITUDE 47.46082 LONGITUDE -122.21248 LOGGED BY BCS CHECKED BY HTW NOTES SURFACE CONDITIONS Field grass AT TIME OF DRILLINGAT TIME OF DRILLING AFTER DRILLING PAGE 2 OF 6 BORING NUMBER B-1 PROJECT NUMBER ES-9099 PROJECT NAME Talbot Road Property GENERAL BH / TP / WELL - 9099.GPJ - GINT US.GDT - 7/18/23Earth Solutions NW, LLC 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 RECOVERY %BLOWCOUNTS(N VALUE)TESTS U.S.C.S.MATERIAL DESCRIPTION GRAPHICLOGDocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C SS SS SS 90 100 91 42-50/4" 24-50/6" 40-50/5" MC = 17.3 MC = 16.2 MC = 18.0 Bedrock SANDSTONE (Renton Formation Bedrock), light gray (N7), medium to coarse grained, fresh (Grade I), very weak to moderately weak rock (R1 to R2) -sample is easily friable -trace coal in sand-sized clasts -easily friableDEPTH(ft)30.0 32.5 35.0 37.5 40.0 42.5 45.0 (Continued Next Page)SAMPLE TYPENUMBERDRILLING CONTRACTOR Holocene Drilling DATE STARTED 5/15/23 COMPLETED 5/15/23 GROUND WATER LEVEL: GROUND ELEVATION 173 ft LATITUDE 47.46082 LONGITUDE -122.21248 LOGGED BY BCS CHECKED BY HTW NOTES SURFACE CONDITIONS Field grass AT TIME OF DRILLINGAT TIME OF DRILLING AFTER DRILLING PAGE 3 OF 6 BORING NUMBER B-1 PROJECT NUMBER ES-9099 PROJECT NAME Talbot Road Property GENERAL BH / TP / WELL - 9099.GPJ - GINT US.GDT - 7/18/23Earth Solutions NW, LLC 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 RECOVERY %BLOWCOUNTS(N VALUE)TESTS U.S.C.S.MATERIAL DESCRIPTION GRAPHICLOGDocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C 118.0 115.0 SS SS SS 100 0 67 25-30- 50/6" 50/6" 12-12-15 (27) MC = 16.4 MC = 27.8 Bedrock ML Bedrock SANDSTONE (Renton Formation Bedrock), light gray (N7), medium to coarse grained, fresh (Grade I), very weak to moderately weak rock (R1 to R2) (continued) -minor scattered coal fragments -inch scale dark brown organic beds -consistent drilling behavior -no recovery Gray SILT, medium dense, wet SILTSTONE (Renton Formation Bedrock), light gray (N7), fine grained, fresh (Grade I), extremely to very weak rock (R1 to R2) 55.0 58.0DEPTH(ft)45.0 47.5 50.0 52.5 55.0 57.5 60.0 (Continued Next Page)SAMPLE TYPENUMBERDRILLING CONTRACTOR Holocene Drilling DATE STARTED 5/15/23 COMPLETED 5/15/23 GROUND WATER LEVEL: GROUND ELEVATION 173 ft LATITUDE 47.46082 LONGITUDE -122.21248 LOGGED BY BCS CHECKED BY HTW NOTES SURFACE CONDITIONS Field grass AT TIME OF DRILLINGAT TIME OF DRILLING AFTER DRILLING PAGE 4 OF 6 BORING NUMBER B-1 PROJECT NUMBER ES-9099 PROJECT NAME Talbot Road Property GENERAL BH / TP / WELL - 9099.GPJ - GINT US.GDT - 7/18/23Earth Solutions NW, LLC 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 RECOVERY %BLOWCOUNTS(N VALUE)TESTS U.S.C.S.MATERIAL DESCRIPTION GRAPHICLOGDocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C SS SS SS 100 100 100 50/3" 32-50/4" 50/3" MC = 12.4 MC = 15.5 MC = 13.4 Bedrock SILTSTONE (Renton Formation Bedrock), light gray (N7), fine grained, fresh (Grade I), extremely to very weak rock (R1 to R2) (continued) -trace fine sand -very slow, consistent drilling to BOH -weak to moderately lithified -retool rig with "drag bit", slightly increased drilling efficiencyDEPTH(ft)60.0 62.5 65.0 67.5 70.0 72.5 75.0 (Continued Next Page)SAMPLE TYPENUMBERDRILLING CONTRACTOR Holocene Drilling DATE STARTED 5/15/23 COMPLETED 5/15/23 GROUND WATER LEVEL: GROUND ELEVATION 173 ft LATITUDE 47.46082 LONGITUDE -122.21248 LOGGED BY BCS CHECKED BY HTW NOTES SURFACE CONDITIONS Field grass AT TIME OF DRILLINGAT TIME OF DRILLING AFTER DRILLING PAGE 5 OF 6 BORING NUMBER B-1 PROJECT NUMBER ES-9099 PROJECT NAME Talbot Road Property GENERAL BH / TP / WELL - 9099.GPJ - GINT US.GDT - 7/18/23Earth Solutions NW, LLC 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 RECOVERY %BLOWCOUNTS(N VALUE)TESTS U.S.C.S.MATERIAL DESCRIPTION GRAPHICLOGDocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C 92.5 SS SS 100 100 50/2" 50/1" MC = 11.2 MC = 22.1 Bedrock SILTSTONE (Renton Formation Bedrock), light gray (N7), fine grained, fresh (Grade I), extremely to very weak rock (R1 to R2) (continued) Boring terminated at 80.5 feet below existing grade. No groundwater encountered during drilling. Boring backfilled with grout. LIMITATIONS: Ground elevation (if listed) is approximate; the test location was not surveyed. Coordinates are approximate and based on the WGS84 datum. Do not rely on this test log as a standalone document. Refer to the text of the geotechnical report for a complete understanding of subsurface conditions. 80.5DEPTH(ft)75.0 77.5 80.0 SAMPLE TYPENUMBERDRILLING CONTRACTOR Holocene Drilling DATE STARTED 5/15/23 COMPLETED 5/15/23 GROUND WATER LEVEL: GROUND ELEVATION 173 ft LATITUDE 47.46082 LONGITUDE -122.21248 LOGGED BY BCS CHECKED BY HTW NOTES SURFACE CONDITIONS Field grass AT TIME OF DRILLINGAT TIME OF DRILLING AFTER DRILLING PAGE 6 OF 6 BORING NUMBER B-1 PROJECT NUMBER ES-9099 PROJECT NAME Talbot Road Property GENERAL BH / TP / WELL - 9099.GPJ - GINT US.GDT - 7/18/23Earth Solutions NW, LLC 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 RECOVERY %BLOWCOUNTS(N VALUE)TESTS U.S.C.S.MATERIAL DESCRIPTION GRAPHICLOGDocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C 160.0 SS SS 100 100 21-31-45 (76) 50/4" MC = 6.0 Fines = 57.8 MC = 13.2 ML Gray sandy SILT, medium dense, moist -rig chatter, becomes very dense [USDA Classification: slightly gravelly LOAM] -light iron oxide staining -minor scattered fine gravel -significant machine chatter 15.0DEPTH(ft)0.0 2.5 5.0 7.5 10.0 12.5 15.0 (Continued Next Page)SAMPLE TYPENUMBERDRILLING CONTRACTOR Holocene Drilling DATE STARTED 5/16/23 COMPLETED 5/16/23 GROUND WATER LEVEL: GROUND ELEVATION 175 ft LATITUDE 47.46107 LONGITUDE -122.21214 LOGGED BY BCS CHECKED BY HTW NOTES SURFACE CONDITIONS Field grass AT TIME OF DRILLINGAT TIME OF DRILLING AFTER DRILLING PAGE 1 OF 3 BORING NUMBER B-2 PROJECT NUMBER ES-9099 PROJECT NAME Talbot Road Property GENERAL BH / TP / WELL - 9099.GPJ - GINT US.GDT - 7/18/23Earth Solutions NW, LLC 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 RECOVERY %BLOWCOUNTS(N VALUE)TESTS U.S.C.S.MATERIAL DESCRIPTION GRAPHICLOGDocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C 150.0 SS SS SS 89 100 100 18-32-46 (78) 50/6" 50/2" MC = 17.8 MC = 17.3 MC = 10.4 Bedrock Bedrock SANDSTONE (Renton Formation Bedrock), moderate yellowish brown (10YR 6/6) and light gray (N7), medium to coarse grained, slightly weathered (Grade II), very weak to moderately weak rock (R1 to R2) -relatively friable rock -slow drilling SILTSTONE (Renton Formation Bedrock), light gray (N7), fine grained, fresh (Grade I), extremely to very weak rock (R0 to R1) -moderately to strongly lithified -very slow, consistent drilling to BOH 25.0DEPTH(ft)15.0 17.5 20.0 22.5 25.0 27.5 30.0 (Continued Next Page)SAMPLE TYPENUMBERDRILLING CONTRACTOR Holocene Drilling DATE STARTED 5/16/23 COMPLETED 5/16/23 GROUND WATER LEVEL: GROUND ELEVATION 175 ft LATITUDE 47.46107 LONGITUDE -122.21214 LOGGED BY BCS CHECKED BY HTW NOTES SURFACE CONDITIONS Field grass AT TIME OF DRILLINGAT TIME OF DRILLING AFTER DRILLING PAGE 2 OF 3 BORING NUMBER B-2 PROJECT NUMBER ES-9099 PROJECT NAME Talbot Road Property GENERAL BH / TP / WELL - 9099.GPJ - GINT US.GDT - 7/18/23Earth Solutions NW, LLC 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 RECOVERY %BLOWCOUNTS(N VALUE)TESTS U.S.C.S.MATERIAL DESCRIPTION GRAPHICLOGDocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C 134.5 SS SS SS 100 100 100 50/5" 50/3" 50/3" MC = 13.7 MC = 11.4 MC = 14.9 Bedrock SILTSTONE (Renton Formation Bedrock), light gray (N7), fine grained, fresh (Grade I), extremely to very weak rock (R0 to R1) (continued) -moderately abundant coal (approximately 20 to 40 percent of sample) present in mm scale laminations -laminations are near vertical in orientation -minor coal (approximately 10 o 15 percent of sample) present in mm scale laminations -laminations are near vertical in orientation Boring terminated at 40.5 feet below existing grade. No groundwater encountered during drilling. Boring backfilled with grout. LIMITATIONS: Ground elevation (if listed) is approximate; the test location was not surveyed. Coordinates are approximate and based on the WGS84 datum. Do not rely on this test log as a standalone document. Refer to the text of the geotechnical report for a complete understanding of subsurface conditions. 40.5DEPTH(ft)30.0 32.5 35.0 37.5 40.0 SAMPLE TYPENUMBERDRILLING CONTRACTOR Holocene Drilling DATE STARTED 5/16/23 COMPLETED 5/16/23 GROUND WATER LEVEL: GROUND ELEVATION 175 ft LATITUDE 47.46107 LONGITUDE -122.21214 LOGGED BY BCS CHECKED BY HTW NOTES SURFACE CONDITIONS Field grass AT TIME OF DRILLINGAT TIME OF DRILLING AFTER DRILLING PAGE 3 OF 3 BORING NUMBER B-2 PROJECT NUMBER ES-9099 PROJECT NAME Talbot Road Property GENERAL BH / TP / WELL - 9099.GPJ - GINT US.GDT - 7/18/23Earth Solutions NW, LLC 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 RECOVERY %BLOWCOUNTS(N VALUE)TESTS U.S.C.S.MATERIAL DESCRIPTION GRAPHICLOGDocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C 172.0 SS SS 100 100 4-6-10 (16) 27-50/3" MC = 18.9 Fines = 42.3 MC = 12.7 SM Bedrock Gray silty SAND, medium dense, moist [USDA Classification: slightly gravelly fine sandy LOAM] -minor scattered fine gravel -light iron oxide staining SANDSTONE (Renton Formation Bedrock), light gray (N7), medium to coarse grained, fresh (Grade I), very weak to moderately weak rock (R1 to R2) -smooth consistent rig behavior to BOH 10.0DEPTH(ft)0.0 2.5 5.0 7.5 10.0 12.5 15.0 (Continued Next Page)SAMPLE TYPENUMBERDRILLING CONTRACTOR Holocene Drilling DATE STARTED 5/16/23 COMPLETED 5/16/23 GROUND WATER LEVEL: GROUND ELEVATION 182 ft LATITUDE 47.46083 LONGITUDE -122.21201 LOGGED BY BCS CHECKED BY HTW NOTES SURFACE CONDITIONS Field grass AT TIME OF DRILLINGAT TIME OF DRILLING AFTER DRILLING PAGE 1 OF 4 BORING NUMBER B-3 PROJECT NUMBER ES-9099 PROJECT NAME Talbot Road Property GENERAL BH / TP / WELL - 9099.GPJ - GINT US.GDT - 7/18/23Earth Solutions NW, LLC 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 RECOVERY %BLOWCOUNTS(N VALUE)TESTS U.S.C.S.MATERIAL DESCRIPTION GRAPHICLOGDocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C SS SS SS 92 100 67 20-50/6" 50/5" 17-18-23 (41) MC = 14.3 MC = 17.9 MC = 17.7 Bedrock SANDSTONE (Renton Formation Bedrock), light gray (N7), medium to coarse grained, fresh (Grade I), very weak to moderately weak rock (R1 to R2) (continued) -near vertical, mm scale coal laminations 0-15% coal -slow drilling, retool rig from tricone bit to drag bit -easily friable -near vertical / steeply diping mm scale coal laminations 0-15% coalDEPTH(ft)15.0 17.5 20.0 22.5 25.0 27.5 30.0 (Continued Next Page)SAMPLE TYPENUMBERDRILLING CONTRACTOR Holocene Drilling DATE STARTED 5/16/23 COMPLETED 5/16/23 GROUND WATER LEVEL: GROUND ELEVATION 182 ft LATITUDE 47.46083 LONGITUDE -122.21201 LOGGED BY BCS CHECKED BY HTW NOTES SURFACE CONDITIONS Field grass AT TIME OF DRILLINGAT TIME OF DRILLING AFTER DRILLING PAGE 2 OF 4 BORING NUMBER B-3 PROJECT NUMBER ES-9099 PROJECT NAME Talbot Road Property GENERAL BH / TP / WELL - 9099.GPJ - GINT US.GDT - 7/18/23Earth Solutions NW, LLC 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 RECOVERY %BLOWCOUNTS(N VALUE)TESTS U.S.C.S.MATERIAL DESCRIPTION GRAPHICLOGDocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C SS SS SS 100 100 100 50/3" 50/5" 50/5" MC = 18.2 MC = 16.5 MC = 18.2 Bedrock SANDSTONE (Renton Formation Bedrock), light gray (N7), medium to coarse grained, fresh (Grade I), very weak to moderately weak rock (R1 to R2) (continued) -trace coal present in mm scale, near vertical laminationsDEPTH(ft)30.0 32.5 35.0 37.5 40.0 42.5 45.0 (Continued Next Page)SAMPLE TYPENUMBERDRILLING CONTRACTOR Holocene Drilling DATE STARTED 5/16/23 COMPLETED 5/16/23 GROUND WATER LEVEL: GROUND ELEVATION 182 ft LATITUDE 47.46083 LONGITUDE -122.21201 LOGGED BY BCS CHECKED BY HTW NOTES SURFACE CONDITIONS Field grass AT TIME OF DRILLINGAT TIME OF DRILLING AFTER DRILLING PAGE 3 OF 4 BORING NUMBER B-3 PROJECT NUMBER ES-9099 PROJECT NAME Talbot Road Property GENERAL BH / TP / WELL - 9099.GPJ - GINT US.GDT - 7/18/23Earth Solutions NW, LLC 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 RECOVERY %BLOWCOUNTS(N VALUE)TESTS U.S.C.S.MATERIAL DESCRIPTION GRAPHICLOGDocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C 136.5 SS 100 50/3"MC = 15.3 Bedrock Boring terminated at 45.5 feet below existing grade. No groundwater encountered during drilling. Boring backfilled with grout. LIMITATIONS: Ground elevation (if listed) is approximate; the test location was not surveyed. Coordinates are approximate and based on the WGS84 datum. Do not rely on this test log as a standalone document. Refer to the text of the geotechnical report for a complete understanding of subsurface conditions. 45.5DEPTH(ft)45.0 SAMPLE TYPENUMBERDRILLING CONTRACTOR Holocene Drilling DATE STARTED 5/16/23 COMPLETED 5/16/23 GROUND WATER LEVEL: GROUND ELEVATION 182 ft LATITUDE 47.46083 LONGITUDE -122.21201 LOGGED BY BCS CHECKED BY HTW NOTES SURFACE CONDITIONS Field grass AT TIME OF DRILLINGAT TIME OF DRILLING AFTER DRILLING PAGE 4 OF 4 BORING NUMBER B-3 PROJECT NUMBER ES-9099 PROJECT NAME Talbot Road Property GENERAL BH / TP / WELL - 9099.GPJ - GINT US.GDT - 7/18/23Earth Solutions NW, LLC 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 RECOVERY %BLOWCOUNTS(N VALUE)TESTS U.S.C.S.MATERIAL DESCRIPTION GRAPHICLOGDocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C 171.0 SS SS 67 100 14-14-19 (33) 25-41- 50/5" MC = 17.4 Fines = 48.4 MC = 12.7 SM Brown silty SAND, dense, moist [USDA Classification: slightly gravelly LOAM] -light iron oxide staining -trace scattered fine gravel -becomes gray, very dense -reduced oxide staining, weakly cemented -significant drilling resistance -rig chatter 15.0DEPTH(ft)0.0 2.5 5.0 7.5 10.0 12.5 15.0 (Continued Next Page)SAMPLE TYPENUMBERDRILLING CONTRACTOR Holocene Drilling DATE STARTED 5/17/23 COMPLETED 5/17/23 GROUND WATER LEVEL: GROUND ELEVATION 186 ft LATITUDE 47.46091 LONGITUDE -122.21164 LOGGED BY BCS CHECKED BY HTW NOTES SURFACE CONDITIONS Field grass AT TIME OF DRILLINGAT TIME OF DRILLING AFTER DRILLING PAGE 1 OF 4 BORING NUMBER B-4 PROJECT NUMBER ES-9099 PROJECT NAME Talbot Road Property GENERAL BH / TP / WELL - 9099.GPJ - GINT US.GDT - 7/18/23Earth Solutions NW, LLC 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 RECOVERY %BLOWCOUNTS(N VALUE)TESTS U.S.C.S.MATERIAL DESCRIPTION GRAPHICLOGDocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C 161.0 SS SS SS 100 100 100 36-45- 50/5" 29-35-47 (82) 50/5" MC = 16.6 Fines = 47.7 MC = 13.4 MC = 14.9 SM Bedrock Brown silty SAND, very dense, moist [USDA Classification: slightly gravelly LOAM] -scattered fine to medium gravel in cemented, silty sand matrix -scattered fine gravel -weakly cemented SANDSTONE (Renton Formation Bedrock), light gray (N7), medium to coarse grained, fresh (Grade I), very weak to moderate weak rock (R1 to R2) -friable rock 25.0DEPTH(ft)15.0 17.5 20.0 22.5 25.0 27.5 30.0 (Continued Next Page)SAMPLE TYPENUMBERDRILLING CONTRACTOR Holocene Drilling DATE STARTED 5/17/23 COMPLETED 5/17/23 GROUND WATER LEVEL: GROUND ELEVATION 186 ft LATITUDE 47.46091 LONGITUDE -122.21164 LOGGED BY BCS CHECKED BY HTW NOTES SURFACE CONDITIONS Field grass AT TIME OF DRILLINGAT TIME OF DRILLING AFTER DRILLING PAGE 2 OF 4 BORING NUMBER B-4 PROJECT NUMBER ES-9099 PROJECT NAME Talbot Road Property GENERAL BH / TP / WELL - 9099.GPJ - GINT US.GDT - 7/18/23Earth Solutions NW, LLC 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 RECOVERY %BLOWCOUNTS(N VALUE)TESTS U.S.C.S.MATERIAL DESCRIPTION GRAPHICLOGDocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C 146.0 SS SS SS 100 100 100 50/4" 31-50/5" 50/3" MC = 13.7 MC = 15.7 MC = 13.2 Bedrock Bedrock SANDSTONE (Renton Formation Bedrock), light gray (N7), medium to coarse grained, fresh (Grade I), very weak to moderate weak rock (R1 to R2) (continued) -mm scale coal laminations -bedding plane is near vertical -decreasing grain size SILTSTONE (Renton Formation Bedrock), light gray (N7), fine grained, fresh (Grade I), extremely to very weak rock (R0 to R1) -trace coal present in mm scale laminations -laminations are near vertical in orientation -increasing sand content 40.0DEPTH(ft)30.0 32.5 35.0 37.5 40.0 42.5 45.0 (Continued Next Page)SAMPLE TYPENUMBERDRILLING CONTRACTOR Holocene Drilling DATE STARTED 5/17/23 COMPLETED 5/17/23 GROUND WATER LEVEL: GROUND ELEVATION 186 ft LATITUDE 47.46091 LONGITUDE -122.21164 LOGGED BY BCS CHECKED BY HTW NOTES SURFACE CONDITIONS Field grass AT TIME OF DRILLINGAT TIME OF DRILLING AFTER DRILLING PAGE 3 OF 4 BORING NUMBER B-4 PROJECT NUMBER ES-9099 PROJECT NAME Talbot Road Property GENERAL BH / TP / WELL - 9099.GPJ - GINT US.GDT - 7/18/23Earth Solutions NW, LLC 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 RECOVERY %BLOWCOUNTS(N VALUE)TESTS U.S.C.S.MATERIAL DESCRIPTION GRAPHICLOGDocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C 140.5 SS 100 50/3"MC = 20.0 Bedrock Boring terminated at 45.5 feet below existing grade. No groundwater encountered during drilling. Boring backfilled with grout. LIMITATIONS: Ground elevation (if listed) is approximate; the test location was not surveyed. Coordinates are approximate and based on the WGS84 datum. Do not rely on this test log as a standalone document. Refer to the text of the geotechnical report for a complete understanding of subsurface conditions. 45.5DEPTH(ft)45.0 SAMPLE TYPENUMBERDRILLING CONTRACTOR Holocene Drilling DATE STARTED 5/17/23 COMPLETED 5/17/23 GROUND WATER LEVEL: GROUND ELEVATION 186 ft LATITUDE 47.46091 LONGITUDE -122.21164 LOGGED BY BCS CHECKED BY HTW NOTES SURFACE CONDITIONS Field grass AT TIME OF DRILLINGAT TIME OF DRILLING AFTER DRILLING PAGE 4 OF 4 BORING NUMBER B-4 PROJECT NUMBER ES-9099 PROJECT NAME Talbot Road Property GENERAL BH / TP / WELL - 9099.GPJ - GINT US.GDT - 7/18/23Earth Solutions NW, LLC 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 RECOVERY %BLOWCOUNTS(N VALUE)TESTS U.S.C.S.MATERIAL DESCRIPTION GRAPHICLOGDocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C 177.0 SS SS 39 100 7-7-6 (13) 25-50/6" MC = 19.4 MC = 12.2 Fines = 48.1 SM Gray silty SAND, medium dense, moist -minor scattered fine to medium gravel [USDA Classification: slightly gravelly LOAM] -becomes very dense, weakly cemented 15.0DEPTH(ft)0.0 2.5 5.0 7.5 10.0 12.5 15.0 (Continued Next Page)SAMPLE TYPENUMBERDRILLING CONTRACTOR Holocene Drilling DATE STARTED 5/17/23 COMPLETED 5/17/23 GROUND WATER LEVEL: GROUND ELEVATION 192 ft LATITUDE 47.46099 LONGITUDE -122.21118 LOGGED BY BCS CHECKED BY HTW NOTES SURFACE CONDITIONS Field grass AT TIME OF DRILLINGAT TIME OF DRILLING AFTER DRILLING PAGE 1 OF 4 BORING NUMBER B-5 PROJECT NUMBER ES-9099 PROJECT NAME Talbot Road Property GENERAL BH / TP / WELL - 9099.GPJ - GINT US.GDT - 7/18/23Earth Solutions NW, LLC 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 RECOVERY %BLOWCOUNTS(N VALUE)TESTS U.S.C.S.MATERIAL DESCRIPTION GRAPHICLOGDocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C 162.0 SS SS SS 100 100 82 50/6" 50/5" 40-50/5" MC = 11.4 MC = 11.1 MC = 11.1 SM Gray silty SAND, very dense, moist -slight rig chatter -trace sand-sized coal fragments incorporated into glacial till deposit 30.0DEPTH(ft)15.0 17.5 20.0 22.5 25.0 27.5 30.0 (Continued Next Page)SAMPLE TYPENUMBERDRILLING CONTRACTOR Holocene Drilling DATE STARTED 5/17/23 COMPLETED 5/17/23 GROUND WATER LEVEL: GROUND ELEVATION 192 ft LATITUDE 47.46099 LONGITUDE -122.21118 LOGGED BY BCS CHECKED BY HTW NOTES SURFACE CONDITIONS Field grass AT TIME OF DRILLINGAT TIME OF DRILLING AFTER DRILLING PAGE 2 OF 4 BORING NUMBER B-5 PROJECT NUMBER ES-9099 PROJECT NAME Talbot Road Property GENERAL BH / TP / WELL - 9099.GPJ - GINT US.GDT - 7/18/23Earth Solutions NW, LLC 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 RECOVERY %BLOWCOUNTS(N VALUE)TESTS U.S.C.S.MATERIAL DESCRIPTION GRAPHICLOGDocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C SS SS SS 100 100 100 50/5" 50/4" 50/6" MC = 12.6 MC = 14.7 MC = 16.5 Bedrock SANDSTONE (Renton Formation Bedrock), light gray (N7), medium to coarse grained, fresh (Grade I), very weak to moderate weak rock (R1 to R2) -friable rock -poorly graded medium to coarse sand grains in silty sand matrixDEPTH(ft)30.0 32.5 35.0 37.5 40.0 42.5 45.0 (Continued Next Page)SAMPLE TYPENUMBERDRILLING CONTRACTOR Holocene Drilling DATE STARTED 5/17/23 COMPLETED 5/17/23 GROUND WATER LEVEL: GROUND ELEVATION 192 ft LATITUDE 47.46099 LONGITUDE -122.21118 LOGGED BY BCS CHECKED BY HTW NOTES SURFACE CONDITIONS Field grass AT TIME OF DRILLINGAT TIME OF DRILLING AFTER DRILLING PAGE 3 OF 4 BORING NUMBER B-5 PROJECT NUMBER ES-9099 PROJECT NAME Talbot Road Property GENERAL BH / TP / WELL - 9099.GPJ - GINT US.GDT - 7/18/23Earth Solutions NW, LLC 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 RECOVERY %BLOWCOUNTS(N VALUE)TESTS U.S.C.S.MATERIAL DESCRIPTION GRAPHICLOGDocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C 141.5 SS SS 100 100 50/5" 50/4" MC = 15.9 MC = 16.3 Bedrock SANDSTONE (Renton Formation Bedrock), light gray (N7), medium to coarse grained, fresh (Grade I), very weak to moderate weak rock (R1 to R2) (continued) -massive (no bedding) Boring terminated at 50.5 feet below existing grade. No groundwater encountered during drilling. Boring backfilled with grout. LIMITATIONS: Ground elevation (if listed) is approximate; the test location was not surveyed. Coordinates are approximate and based on the WGS84 datum. Do not rely on this test log as a standalone document. Refer to the text of the geotechnical report for a complete understanding of subsurface conditions. 50.5DEPTH(ft)45.0 47.5 50.0 SAMPLE TYPENUMBERDRILLING CONTRACTOR Holocene Drilling DATE STARTED 5/17/23 COMPLETED 5/17/23 GROUND WATER LEVEL: GROUND ELEVATION 192 ft LATITUDE 47.46099 LONGITUDE -122.21118 LOGGED BY BCS CHECKED BY HTW NOTES SURFACE CONDITIONS Field grass AT TIME OF DRILLINGAT TIME OF DRILLING AFTER DRILLING PAGE 4 OF 4 BORING NUMBER B-5 PROJECT NUMBER ES-9099 PROJECT NAME Talbot Road Property GENERAL BH / TP / WELL - 9099.GPJ - GINT US.GDT - 7/18/23Earth Solutions NW, LLC 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 RECOVERY %BLOWCOUNTS(N VALUE)TESTS U.S.C.S.MATERIAL DESCRIPTION GRAPHICLOGDocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C Earth Solutions NW, LLC Appendix B Laboratory Test Results ES-9099 DocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 0.0010.010.1110100 3 D100 140 Specimen Identification 1 fine 6 HYDROMETER 304 49.2 57.8 42.3 48.4 47.7 101/2 COBBLES Specimen Identification 4 coarse 20 401.5 8 14 USDA: Gray Slightly Gravelly Loam. USCS: SM. USDA: Gray Slightly Gravelly Loam. USCS: Sandy ML. USDA: Gray Slightly Gravelly Fine Sandy Loam. USCS: SM. USDA: Brown Slightly Gravelly Loam. USCS: SM. USDA: Gray Slightly Gravelly Loam. USCS: SM. 6 60 PERCENT FINER BY WEIGHTD10 0.143 0.089 0.17 0.151 0.167 GRAIN SIZE DISTRIBUTION 100 LL B-01 B-02 B-03 B-04 B-04 3/4 U.S. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS GRAVEL SAND 19 19 19 19 19 %Silt B-01 B-02 B-03 B-04 B-04 2 2003 Cc CuClassification %Clay 16 PID60 D30 coarse SILT OR CLAYfinemedium GRAIN SIZE IN MILLIMETERS 3/8 50 5.0ft. 5.0ft. 5.0ft. 5.0ft. 15.0ft. 5.00ft. 5.00ft. 5.00ft. 5.00ft. 15.00ft. PL PROJECT NUMBER ES-9099 PROJECT NAME Talbot Road Property GRAIN SIZE USDA ES-9099 TALBOT ROAD PROPERTY.GPJ GINT US LAB.GDT 6/2/23Earth Solutions NW, LLC 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 DocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 0.0010.010.1110100 3 D100 140 Specimen Identification 1 fine 6 HYDROMETER 304 48.1 101/2 COBBLES Specimen Identification 4 coarse 20 401.5 8 14 USDA: Gray Slightly Gravelly Loam. USCS: SM. 6 60 PERCENT FINER BY WEIGHTD10 0.158 GRAIN SIZE DISTRIBUTION 100 LL B-05 3/4 U.S. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS GRAVEL SAND 19 %Silt B-05 2 2003 Cc CuClassification %Clay 16 PID60 D30 coarse SILT OR CLAYfinemedium GRAIN SIZE IN MILLIMETERS 3/8 50 10.0ft. 10.00ft. PL PROJECT NUMBER ES-9099 PROJECT NAME Talbot Road Property GRAIN SIZE USDA ES-9099 TALBOT ROAD PROPERTY.GPJ GINT US LAB.GDT 6/2/23Earth Solutions NW, LLC 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 DocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C Earth Solutions NW, LLC Report Distribution ES-9099 Seattle LLL, LLC Attention: Lili Lu D.R. Strong Consulting Engineers Attention: Maher Joudi, P.E. DocuSign Envelope ID: 3AB65E25-59D2-48AF-A2E4-184C4FA9F94C