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Home My WebLink AboutEX_07_Geotechnical ReportEarthSolutionsNWLLC EarthSolutionsNWLLC 15365 N.E. 90th Street, Suite 100 Redmond, WA98052 (425) 449-4704 Fax (425) 449-4711 www.earthsolutionsnw.com Geotechnical Engineering Construction Observation/Testing Environmental Services GEOTECHNICAL ENGINEERING STUDY PROPOSED SHORT PLAT 3804 MEADOW AVENUE NORTH RENTON, WASHINGTON ES-7126 PREPARED FOR MR. HUY NGUYEN March 12, 2020 _________________________ Brian C. Snow, G.I.T. Staff Geologist _________________________ Keven D. Hoffmann, P.E. Senior Project Manager GEOTECHNICAL ENGINEERING STUDY PROPOSED SHORT PLAT 3804 MEADOW AVENUE NORTH RENTON, WASHINGTON ES-7126 Earth Solutions NW, LLC 15365 Northeast 90th Street, Suite 100 Redmond, Washington 98052 Phone: 425-449-4704 | Fax: 425-449-4711 www.earthsolutionsnw.com 03/16/2020 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 ReportGeotechnical-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 TimesGeotechnical 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 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 GuidanceSome 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 March 12, 2020 ES-7126 Mr. Huy Nguyen 15400 Southeast 155th Place, Unit 99 Renton, Washington 98058 Dear Mr. Nguyen: Earth Solutions NW, LLC (ESNW), is pleased to present this geotechnical report for the subject site. While specific site plans were not available at the time of this report, we presume the site will be developed into a short plat, comprised of several two- to three-story residential structures and related infrastructure improvements. Based on the results of our study, construction of a short plat is feasible from a geotechnical standpoint. Based on the conditions observed during the fieldwork, the subject site is underlain primarily by medium dense recessional outwash deposits. The proposed structures can be supported on conventional spread and continuous foundations bearing on undisturbed competent native soil, recompacted native soil, or new structural fill. We anticipate competent native soil suitable for support of foundations will be encountered beginning at depths of about two to four feet below existing grades across the site. This report provides geotechnical analyses and recommendations for the proposed short plat. 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, G.I.T. Staff Geologist 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 Earth Solutions NW, LLC Table of Contents ES-7126 PAGE INTRODUCTION ................................................................................. 1 General..................................................................................... 1 Project Description ................................................................. 2 SITE CONDITIONS ............................................................................. 2 Surface ..................................................................................... 2 Subsurface .............................................................................. 2 Topsoil and Fill ............................................................. 2 Native Soil ..................................................................... 3 Geologic Setting ........................................................... 3 Groundwater ................................................................. 3 GEOLOGICALLY HAZARDOUS AREAS EVALUATION .................. 3 Erosion Hazard ........................................................................ 4 Landslide Hazard .................................................................... 4 Regulated Slopes .................................................................... 5 Seismic Hazard ....................................................................... 5 Analysis of Proposal .............................................................. 6 DISCUSSION AND RECOMMENDATIONS ....................................... 6 General..................................................................................... 6 Site Preparation and Earthwork ............................................. 6 Temporary Erosion Control ......................................... 6 In-Situ and Imported Soil ............................................. 6 Structural Fill ................................................................ 7 Subgrade Preparation .................................................. 7 Excavations and Slopes .............................................. 7 Foundations ............................................................................ 8 Seismic Design ....................................................................... 9 Slab-on-Grade Floors ............................................................. 9 Retaining Walls ....................................................................... 9 Drainage................................................................................... 10 Infiltration Evaluation ................................................... 10 Utility Support and Trench Backfill ....................................... 11 LIMITATIONS ...................................................................................... 11 Additional Services ................................................................. 11 Earth Solutions NW, LLC Table of Contents Continued ES-7126 GRAPHICS Plate 1 Vicinity Map Plate 2 Test Pit Location Plan Plate 3 Retaining Wall Drainage Detail Plate 4 Footing Drain Detail APPENDICES Appendix A Subsurface Exploration Test Pit Logs Appendix B Laboratory Test Results Earth Solutions NW, LLC GEOTECHNICAL ENGINEERING STUDY PROPOSED SHORT PLAT 3804 MEADOW AVENUE NORTH RENTON, WASHINGTON ES-7126 INTRODUCTION General This geotechnical engineering study (study) was prepared for the proposed short plat to be constructed on the east side of Meadow Avenue North, nearest the intersection with North 38th Street, in the Kennydale neighborhood of Renton, Washington. To complete the scope of services, we performed the following:  Subsurface exploration to characterize the soil and groundwater conditions;  In-situ infiltration testing;  Laboratory testing of representative soil samples collected on site;  Review of on-site geologically hazardous areas;  Engineering analyses and recommendations for the proposed short plat, and;  Preparation of this report. The following documents and resources were reviewed as part of our report preparation:  Preliminary Geologic Map of Seattle and Vicinity, Washington, compiled by H.H. Waldron et al., dated 1961;  Web Soil Survey (WSS) online resource, maintained by the Natural Resources Conservation Service (NRCS) under the United States Department of Agriculture (USDA);  Soil Survey of Snoqualmie Pass Area, Parts of King and Pierce Counties, Washington, prepared by the United States Department of Agriculture Soil Conservation Service, dated 1990;  Soil Survey of King County Area, Washington, prepared by the United States Department of Agriculture Soil Conservation Service, dated 1973;  Liquefaction Susceptibility Map 11-5, prepared by the King County Flood Control District, dated May 2010;  Renton Municipal Code (RMC);  City of Renton Critical Areas Map: Online “COR Maps”, and;  City of Renton Surface Water Design Manual. Mr. Huy Nguyen ES-7126 March 12, 2020 Page 2 Earth Solutions NW, LLC Project Description We understand the proposed project will likely consist of constructing a three-lot short plat and associated improvements. At the time this report was prepared, neither site plans nor building load values were available for review. However, we anticipate the proposed residential structures will be two to three stories and constructed using relatively lightly loaded wood framing supported atop conventional foundation systems. Based on our experience with similar developments, we estimate wall loads of about 1 to 2 kips per linear foot and slab-on-grade loading of 150 pounds per square foot (psf) will be incorporated into final designs. Grade cuts and fills to establish individual-lot subgrade and finish grade elevations are expected to be less than five feet. Stormwater management will presumably use infiltration to the extent feasible. If the above design assumptions are incorrect or change, ESNW should be contacted to review the recommendations provided in this report. ESNW should review the final designs to verify the geotechnical recommendations provided in this report have been incorporated into the plans. SITE CONDITIONS Surface The subject site is located northeast of the intersection between North 38th Street and Meadow Avenue North, in Renton, Washington. The approximate location of the property is illustrated on Plate 1 (Vicinity Map). The site is comprised of one tax parcel (King County Parcel No. 334270- 0570), totaling about 0.59 acres. The site is currently developed with a single-family residence and a detached shed structure. The existing topography is relatively level, with less than two feet of elevation change across the site. To the east of the sound barrier wall, grades descend sharply to the Interstate 405 corridor. Subsurface An ESNW representative observed, logged, and sampled five test pits on February 17, 2020. The test pits were excavated at accessible locations within the property, using a mini-trackhoe and operator retained by our firm. The approximate locations of the test pits are depicted on Plate 2 (Test Pit Location Plan). Please refer to the test pit logs provided in Appendix A for a more detailed description of subsurface conditions. Representative soil samples collected at the test pit locations were analyzed in general accordance with Unified Soil Classification System (USCS) and USDA methods and procedures. Topsoil and Fill Topsoil was generally encountered within the upper 6 to 42 inches of existing grades where test pits were excavated. In some instances, relic topsoil horizons were observed beneath fill soil. The topsoil was characterized by a dark brown color, the presence of fine organic material, and small root intrusions. Root zones extended between about four to five feet below the existing ground surface (bgs). Mr. Huy Nguyen ES-7126 March 12, 2020 Page 3 Earth Solutions NW, LLC Fill was observed at test pit locations TP-1, TP-2, TP-3, and TP-4, extending to a maximum depth of about five feet bgs. The fill soil generally consisted of tan silty sand with minor interbedded topsoil. In TP-4, rebar, plastic bags, and wood debris was observed. Native Soil Underlying the topsoil and fill, the native soil consisted primarily of medium dense silty sand and poorly graded sand with variable silt and gravel content (USCS: SM, SP, and SP-SM). The native deposits were primarily observed in a wet condition at the time of our exploration, and weak iron oxide staining was noted at several locations. The maximum exploration depth was roughly nine feet bgs. Geologic Setting Geologic mapping of the area indicates the site is underlain by younger gravel (Qyg) and younger sand (Qys) as part of the Vashon recessional outwash series. Recessional outwash was deposited by glacial meltwater and is readily comprised of silt, clay, sand, and gravel. The referenced WSS resource identifies Indianola loamy sand (Map Unit Symbol: InC) across the majority of the site, with Norma sandy loam (Map Unit Symbol: No) mapped along the eastern edge. The Indianola loamy sands were formed in eskers, kames, and terraces, and the Norma sandy loams were formed in flood plains. Based on our field observations, the native soil on site is generally consistent with the geologic and soil mapping resources outlined in this section. Groundwater During the subsurface exploration, perched groundwater seepage was encountered at test pit locations TP-3 and TP-4 at eight-and-one-half and five-and-one-half feet bgs, respectively. Groundwater seepage may be encountered within site excavations depending on the time of year and extent of grading activities. Seepage rates and elevations 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. GEOLOGICALLY HAZARDOUS AREAS EVALUATION To evaluate geologically hazardous areas, we reviewed Chapter 4-3 of the City of Renton (City) Municipal Code (RMC). The RMC provides designation and definition criteria for identifying specific geologically hazardous areas and developing appropriate site development plans which will not adversely impact the site or surrounding properties. According to the referenced City Critical Areas Map, erosion hazards, landslide hazards, and regulated slopes are all mapped within 50 feet of the subject site. The mapped hazards are largely associated with the hillslope east of the subject site (outside of the property boundaries) and bordering Interstate 405. Additionally, a seismic hazard area is mapped within 500 feet of the subject site. Mr. Huy Nguyen ES-7126 March 12, 2020 Page 4 Earth Solutions NW, LLC Erosion Hazard According to RMC 4-3-050G5c, erosion hazard areas can be defined as: i. Low Erosion Hazard (EL): Areas with soils characterized by the NRCS as having slight or moderate erosion potential and a slope less than 15 percent. ii. High Erosion Hazard (EH): Areas with soils characterized by the NRCS as having severe or very severe erosion potential and a slope greater than 15 percent. The referenced City Critical Areas Map designates a high erosion hazard on the eastern slope of the site (bordering Interstate 405). The site soils are predominantly mapped as Indianola loamy sand (Map Unit Symbol: InC), with Norma sandy loam (Map Unit Symbol: No) along the eastern edge. The USDA SCS 1973 King County Soils Survey classifies the erosion hazard of Indianola soils as slight to moderate. The USDA SCS 1990 Snoqualmie Pass Area Soil Survey states there is no hazard of erosion associated with Norma soils. In our opinion, given that the site topography is relatively level, the site soils within the proposed development areas generally exhibit low erosivity potential in a typical construction setting. Best Management Practices (BMPs), in general accordance with City surface water and stormwater regulations, should be used for site design and development. At a minimum, silt fencing should be placed along the entire development envelope, and soil stockpiles should be covered when not in use. If construction occurs during periods of wet weather, methods to control surface water runoff will likely be necessary. Construction entrances should be surfaced with quarry spalls to minimize off-site tracking of silt and soil generated during site construction. Landslide Hazard Per RMC 4-3-050G5b, landslide hazard areas can be defined as: i. Low Landslide Hazard (LL): Areas with slopes less than 15 percent. ii. Medium Landslide Hazard (LM): Areas with slopes between 15 percent and 40 percent, underlain by soils that consist largely of sand, gravel, or glacial till. iii. High Landslide Hazards (LH): Areas with slopes greater than 40 percent and areas with slopes between 15 percent and 40 percent underlain by soils consisting largely of silt and clay. iv. Very High Landslide Hazards (LV): Areas of known mapped or identified landslide deposits. The referenced City Critical Areas Map designates a landslide hazard on the eastern slope bordering Interstate 405. In our opinion, given that the slope is largely vegetated with blackberries, trees, and other shrubs; has a slope of about 31 percent; and is outside of the proposed development area, the landslide hazard may be characterized as low to medium. Mr. Huy Nguyen ES-7126 March 12, 2020 Page 5 Earth Solutions NW, LLC Regulated Slopes According to RMC 4-3-050G5a, steep slopes may be categorized into two types: i. Sensitive Slopes: A hillside, or portion thereof (excluding engineering retaining walls), characterized by: a. An average slope of 25 percent to less than 40 percent, as identified in the City Steep Slope Atlas or in a method approved by the City, or; b. An average slope of 40 percent or greater, with a vertical rise of less than 15 feet, as identified in the City Steep Slope Atlas or in a method approved by the City; c. Abutting an average slope of 25 percent to 40 percent, as identified in the City Steep Slope Atlas or in a method approved by the City. ii. Protected Slopes: A hillside, or portion thereof, characterized by an average slope of 40 percent or greater grade and having a minimum vertical rise of 15 feet, as identified in the City Steep Slope Atlas or in a method approved by the City. The referenced City Critical Areas Map designates portions of the eastern slope both as sensitive and protected slopes. Because the eastern slope is located outside of and well away from the anticipated grading and construction activities, it is our opinion that the designations of sensitive and/or protected slopes on site should not impact the proposed short plat from a geotechnical standpoint. Seismic Hazard Per RMC 4-3-050G5d, seismic hazard areas can be defined as: i. Low Seismic Hazard (SL): Areas underlain by dense soils or bedrock. These soils generally have site classifications of A through D, as defined in the 2012 International Building Code (2012 IBC). ii. High Seismic Hazard (SH): Areas underlain by soft or loose, saturated soils. These soils generally have site classifications E or F, as defined in the 2012 IBC. The referenced City Critical Areas Map designates a seismic hazard area approximately 260 feet to the east of the subject site. Based on the conditions observed during our subsurface exploration and the lack of an established, shallow groundwater table, it is our opinion that the seismic hazard on site is low. The referenced Liquefaction Susceptibility Map identifies low potential for liquefaction at the subject site. Mr. Huy Nguyen ES-7126 March 12, 2020 Page 6 Earth Solutions NW, LLC Analysis of Proposal ESNW should be contacted to review both the preliminary and final project plans to further evaluate the proposed construction and any potential impacts to geologically hazardous areas. If more significant grading activities or larger-than-anticipated residential structures are proposed, ESNW should reevaluate the potential impacts to the adjacent hazard areas. DISCUSSION AND RECOMMENDATIONS General Based on the results of our investigation, construction of the proposed short plat is feasible from a geotechnical standpoint. The primary geotechnical considerations associated with the proposed development include site preparation and earthwork, suitability of on-site soil as structural fill, subgrade preparation, temporary excavations, building foundations, retaining walls, drainage, and infiltration feasibility. 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 infrastructure and utility installations. Temporary Erosion Control Erosion control measures should conform to the standards and requirements of the Washington State Department of Ecology, King County, and City, where applicable. Please refer to the Erosion Hazard section of this report for a more detailed discussion on recommended temporary erosion and sediment control measures during construction. In-Situ and Imported Soil The majority of the soils encountered during our subsurface exploration have a moderate to high sensitivity to moisture and were generally in a wet condition at the time of exploration. The soils anticipated to be exposed at this site will degrade if exposed to wet weather and construction traffic. Compaction of the soils to the levels necessary for use as structural fill may be difficult or impossible during wet weather conditions. 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 determine the suitability of in-situ soils for use as structural fill at the time of construction. Mr. Huy Nguyen ES-7126 March 12, 2020 Page 7 Earth Solutions NW, LLC 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). 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 existing soil 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 optimum and should be evaluated by ESNW during construction With respect to underground utility installations and backfill, local jurisdictions may dictate the soil type(s) and compaction requirements. Areas of otherwise unsuitable material and debris should be removed from structural areas and replaced with structural fill. Subgrade Preparation Following site stripping, ESNW should observe the subgrade to confirm soil conditions are as anticipated and to provide supplementary recommendations for subgrade preparation as necessary. In general, foundation subgrade surfaces should be compacted in situ to a minimum depth of one foot below the design subgrade elevation. Uniform compaction of the foundation and slab subgrade areas will establish a relatively consistent subgrade condition below the foundation and slab elements. 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. Excavations and Slopes Excavation activities on site are likely to expose loose to medium dense native soil beginning at depths of approximately two to four feet bgs. Based on the soil conditions observed at the subsurface exploration locations, the following maximum allowable temporary slope inclinations may be used. Mr. Huy Nguyen ES-7126 March 12, 2020 Page 8 Earth Solutions NW, LLC The applicable Federal Occupation Safety and Health Administration and Washington Industrial Safety and Health Act soil classifications are also provided:  Areas exposing groundwater seepage 1.5H:1V (Type C)  Loose soil; fill 1.5H:1V (Type C)  Medium dense to dense native soil 1H:1V (Type B) Permanent slopes should be planted with vegetation to both enhance stability and minimize erosion and should maintain a gradient of 2H:1V or flatter. The presence of perched groundwater may cause localized sloughing of temporary slopes. 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. Foundations The proposed residential structures can be supported on conventional spread and continuous footings bearing on undisturbed competent native soil, compacted native soil, or new structural fill. We anticipate competent native soil suitable for support of foundations will be encountered at a depth of about two to four feet below existing grades. Where loose or unsuitable soil conditions are encountered at foundation subgrade elevations, compaction of the soils to the specifications of structural fill or overexcavation and replacement with suitable structural fill will likely be necessary. Provided the structure 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. The majority of the settlement should occur during construction when dead loads are applied. Mr. Huy Nguyen ES-7126 March 12, 2020 Page 9 Earth Solutions NW, LLC Seismic Design The 2015 IBC recognizes the American Society of Civil Engineers (ASCE) for seismic site class definitions. In accordance with Table 20.3-1 of the ASCE Minimum Design Loads for Buildings and Other Structures Manual, Site Class D should be used for design. Please refer to the Seismic Hazard section of this report for an opinion of the site-specific seismic hazard. 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- quarters-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. 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 6H 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. 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. Mr. Huy Nguyen ES-7126 March 12, 2020 Page 10 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. 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 3. If drainage is not provided, hydrostatic pressures should be included in the wall design. Drainage Discrete zones of perched groundwater seepage should be anticipated in 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 interceptor trenches, interceptor swales, and sumps. ESNW should be consulted during preliminary grading to both identify areas of seepage and provide recommendations to reduce the potential for seepage-related instability. 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, foundation drains should be installed along building perimeter footings. A typical foundation drain detail is provided on Plate 4. Infiltration Evaluation In accordance with the 2017 City of Renton Surface Water Design Manual (2017 RSWDM), a small-scale Pilot Infiltration Test (PIT) was completed at test pit location TP-2. The PIT was completed by excavating a roughly three-foot by four-foot (infiltration surface) test pit to a depth of about three and one-half feet bgs and following the prescribed PIT procedure as outlined in the 2017 RSWDM. Based on the results of the PIT, the following design parameters are recommended:  Measured infiltration rate 10 inches per hour (iph)  Total correction factor 0.5  Design infiltration rate 5 iph The correction factor of 0.5 was selected based on the guidelines provided in the 2017 RSWDM. In our opinion, a correction factor of 0.5 is suitable for the observed conditions at the testing location. At this time, the design infiltration rate of 5 iph is applicable only at the location of TP-2 and only at the infiltration test depth. ESNW should be contacted to review stormwater management plans if infiltration is used for design. Supplementary recommendations and/or testing may be necessary depending on the size, depth, and siting of infiltration facilities. Mr. Huy Nguyen ES-7126 March 12, 2020 Page 11 Earth Solutions NW, LLC Utility Support and Trench Backfill The soils observed at the subsurface exploration locations are generally suitable for support of utilities. 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. Native soil will be difficult or impossible to use as utility trench backfill during wet weather conditions. 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. LIMITATIONS This study has been prepared for the exclusive use of Mr. Huy Nguyen and his representatives. The recommendations and conclusions provided in the geotechnical engineering 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 not expressed or implied. Variations in the soil and groundwater conditions observed at the test locations may exist and may not become evident until construction. ESNW should reevaluate the conclusions provided in this geotechnical engineering study if variations are encountered. Additional Services ESNW should have an opportunity to review the final design with respect to the geotechnical recommendations provided in this report. ESNW should also be retained to provided testing and consultation services during construction. Drwn. MRS Checked BCS Date Mar. 2020 Date 03/13/2020 Proj. No. 7126 Plate 1 Earth Solutions NWLLC Geotechnical Engineering,Construction EarthSolutionsNWLLC EarthSolutionsNWLLC Observation/Testing and Environmental Services Vicinity Map Meadow Avenue Short Plat 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 Newcastle Renton Drwn. MRS Checked BCS Date Mar. 2020 Date 03/13/2020 Proj. No. 7126 Plate 2 Earth Solutions NWLLC Geotechnical Engineering,Construction EarthSolutionsNWLLC EarthSolutionsNWLLC Observation/Testing and Environmental Services Test Pit Location Plan Meadow Avenue Short Plat Renton, Washington NORTH 0 30 60 120 Scale in Feet 1"=60' 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. LEGEND Approximate Location of ESNW Test Pit, Proj. No. ES-7126, Feb. 2020 Subject Site Existing Building Proposed Lot Letter A B C Sound Barrier Wall TP-1 TP-2 TP-3 TP-4 TP-5 TP-1 130 130MEADOW AVENUE N.SR-405A N. 38TH STREET Drwn. MRS Checked BCS Date Mar. 2020 Date 03/13/2020 Proj. No. 7126 Plate 3 Earth Solutions NWLLCEarthSolutionsNWLLC EarthSolutionsNWLLC Geotechnical Engineering,Construction Observation/Testing and Environmental Services Retaining Wall Drainage Detail Meadow Avenue Short Plat Renton, Washington 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 DRAWING Drwn. MRS Checked BCS Date Mar. 2020 Date 03/13/2020 Proj. No. 7126 Plate 4 Earth Solutions NWLLC Geotechnical Engineering,Construction Observation/Testing and Environmental Services EarthSolutionsNWLLC EarthSolutionsNWLLC Footing Drain Detail Meadow Avenue Short Plat Renton, Washington 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 DRAWING Earth Solutions NW, LLC Appendix A Subsurface Exploration Test Pit Logs ES-7126 Subsurface conditions on site were explored on February 17, 2020, by excavating five test pits using a mini-trackhoe and operator retained by our firm. The approximate locations of the test pits are illustrated on Plate 2 of this study. The test pit logs are provided in this Appendix. The test pits were advanced to a maximum depth of about nine 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. GRAVEL AND GRAVELLYSOILS CLAYEY GRAVELS, GRAVEL - SAND - CLAY MIXTURES WELL-GRADED SANDS, GRAVELLYSANDS, LITTLE OR NO FINES POORLY-GRADED SANDS,GRAVELLY SAND, LITTLE OR NO FINES SILTY SANDS, SAND - SILTMIXTURES CLAYEY SANDS, SAND - CLAYMIXTURES INORGANIC SILTS AND VERY FINESANDS, ROCK FLOUR, SILTY OR CLAYEY FINE SANDS OR CLAYEYSILTS WITH SLIGHT PLASTICITY INORGANIC CLAYS OF LOW TO MEDIUM PLASTICITY, GRAVELLYCLAYS, SANDY CLAYS, SILTY CLAYS,LEAN CLAYS ORGANIC SILTS AND ORGANICSILTY CLAYS OF LOW PLASTICITY INORGANIC SILTS, MICACEOUS OR DIATOMACEOUS FINE SAND ORSILTY SOILS INORGANIC CLAYS OF HIGHPLASTICITY SILTSANDCLAYS MORE THAN 50% OF MATERIAL ISLARGER THANNO. 200 SIEVE SIZE MORE THAN 50%OF MATERIAL IS SMALLER THANNO. 200 SIEVESIZE MORE THAN 50%OF COARSEFRACTION PASSING ON NO.4 SIEVE MORE THAN 50%OF COARSEFRACTION RETAINED ON NO.4 SIEVE SOIL CLASSIFICATION CHART (APPRECIABLEAMOUNT OF FINES) (APPRECIABLE AMOUNT OF FINES) (LITTLE OR NO FINES) FINEGRAINEDSOILS SAND AND SANDY SOILS SILTS AND CLAYS ORGANIC CLAYS OF MEDIUM TO HIGH PLASTICITY, ORGANIC SILTS PEAT, HUMUS, SWAMP SOILS WITHHIGH ORGANIC CONTENTS LETTERGRAPH SYMBOLSMAJOR DIVISIONS COARSE GRAINEDSOILS TYPICAL DESCRIPTIONS WELL-GRADED GRAVELS, GRAVEL -SAND MIXTURES, LITTLE OR NO FINES POORLY-GRADED GRAVELS, GRAVEL - SAND MIXTURES, LITTLEOR NO FINES SILTY GRAVELS, GRAVEL - SAND - SILT MIXTURES CLEANGRAVELS GRAVELS WITH FINES CLEAN SANDS (LITTLE OR NO FINES) SANDS WITH FINES LIQUID LIMITLESS THAN 50 LIQUID LIMITGREATER THAN 50 HIGHLY ORGANIC SOILS DUAL SYMBOLS are used to indicate borderline soil classifications. The discussion in the text of this report is necessary for a proper understanding of the nature of the material presented in the attached logs. GW GP GM GC SW SP SM SC ML CL OL MH CH OH PT Earth Solutions NW LLC 127.5 126.5 123.0 122.0 MC = 16.20% MC = 18.40% MC = 2.90% Fines = 1.40% MC = 21.90% SM TPSL SP SM Brown silty SAND, medium dense, moist (Fill) Relic TOPSOIL Horizon Tan poorly graded SAND with gravel, medium dense, moist [USDA Classification: very gravelly coarse SAND] Tan silty SAND, medium dense, moist Test pit terminated at 8.0 feet below existing grade. No groundwater encountered during excavation. No caving observed. 2.5 3.5 7.0 8.0 NOTES Surface Conditions: gravel GROUND ELEVATION 130 ft LOGGED BY BCS EXCAVATION METHOD TEST PIT SIZE EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS: CHECKED BY KDH DATE STARTED 2/17/20 COMPLETED 2/17/20 AT TIME OF EXCAVATION --- AT END OF EXCAVATION --- AFTER EXCAVATION ---SAMPLE TYPENUMBERDEPTH(ft)0 5 PAGE 1 OF 1 TEST PIT NUMBER TP-1 PROJECT NUMBER ES-7126 PROJECT NAME Meadow Avenue Short Plat GENERAL BH / TP / WELL - 7126.GPJ - GINT STD US.GDT - 3/16/20Earth Solutions NW, LLC 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 TESTS U.S.C.S.MATERIAL DESCRIPTION GRAPHICLOG 128.5 127.5 127.0 125.0 120.5 MC = 11.00% MC = 20.50%Fines = 33.20% MC = 27.70% Fines = 8.20% MC = 19.20% MC = 14.70%Fines = 5.10% TPSL SM TPSL SM SP-SM Dark brown TOPSOIL, root intrusions to 5' (Fill) Tan silty SAND, medium dense, moist (Fill) Relic TOPSOIL Horizon Tan silty SAND, medium dense, moist -slight caving to BOH -infiltration test, [USDA Classification: slightly gravelly very fine sandy LOAM] Gray poorly graded SAND with silt, medium dense, wet [USDA Classification: slightly gravelly SAND] -weak iron oxide staining to 8' -becomes poorly graded sand with gravel [USDA Classification: gravelly coarse SAND] Test pit terminated at 8.5 feet below existing grade. No groundwater encountered duringexcavation. Caving observed from 3.0 feet to BOH. 0.5 1.5 2.0 4.0 8.5 NOTES Depth of Topsoil & Sod 6": grass GROUND ELEVATION 129 ft LOGGED BY BCS EXCAVATION METHOD TEST PIT SIZE EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS: CHECKED BY KDH DATE STARTED 2/17/20 COMPLETED 2/17/20 AT TIME OF EXCAVATION --- AT END OF EXCAVATION --- AFTER EXCAVATION ---SAMPLE TYPENUMBERDEPTH(ft)0 5 PAGE 1 OF 1 TEST PIT NUMBER TP-2 PROJECT NUMBER ES-7126 PROJECT NAME Meadow Avenue Short Plat GENERAL BH / TP / WELL - 7126.GPJ - GINT STD US.GDT - 3/16/20Earth Solutions NW, LLC 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 TESTS U.S.C.S.MATERIAL DESCRIPTION GRAPHICLOG 129.5 127.0 126.0 121.5 MC = 15.20% MC = 11.40% Fines = 15.20% MC = 22.90% MC = 23.10% TPSL SM TPSL SM Dark brown TOPSOIL (Fill) Brown silty SAND, medium dense, moist (Fill) Relic TOPSOIL Horizon -charcoal fragments Tan silty SAND, medium dense, moist -weak iron oxide staining -at 4' [USDA Classification: slightly gravelly loamy SAND] -becomes gray, light groundwater seepage at 8.5' Test pit terminated at 8.5 feet below existing grade. Groundwater seepage encountered at8.5 feet during excavation. No caving observed. 0.5 3.0 4.0 8.5 NOTES Depth of Topsoil & Sod 6": grass GROUND ELEVATION 130 ft LOGGED BY BCS EXCAVATION METHOD TEST PIT SIZE EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS: CHECKED BY KDH DATE STARTED 2/17/20 COMPLETED 2/17/20 AT TIME OF EXCAVATION --- AT END OF EXCAVATION --- AFTER EXCAVATION ---SAMPLE TYPENUMBERDEPTH(ft)0 5 PAGE 1 OF 1 TEST PIT NUMBER TP-3 PROJECT NUMBER ES-7126 PROJECT NAME Meadow Avenue Short Plat GENERAL BH / TP / WELL - 7126.GPJ - GINT STD US.GDT - 3/16/20Earth Solutions NW, LLC 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 TESTS U.S.C.S.MATERIAL DESCRIPTION GRAPHICLOG 125.5 121.0 MC = 22.60% MC = 24.30% MC = 18.40% SM SM Tan silty SAND, medium dense, moist (Fill) -becomes brown -interbedded dark brown TOPSOIL in fill -rebar, plastic bags, and wood debris Gray silty SAND, medium dense, moist -weak iron oxide staining -light groundwater seepage Test pit terminated at 9.0 below existing grade. Groundwater seepage encountered at 5.5feet during excavation. Caving observed from 1.5 to 5.0 feet. 4.5 9.0 NOTES Surface Conditions: gravel GROUND ELEVATION 130 ft LOGGED BY BCS EXCAVATION METHOD TEST PIT SIZE EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS: CHECKED BY KDH DATE STARTED 2/17/20 COMPLETED 2/17/20 AT TIME OF EXCAVATION --- AT END OF EXCAVATION --- AFTER EXCAVATION ---SAMPLE TYPENUMBERDEPTH(ft)0 5 PAGE 1 OF 1 TEST PIT NUMBER TP-4 PROJECT NUMBER ES-7126 PROJECT NAME Meadow Avenue Short Plat GENERAL BH / TP / WELL - 7126.GPJ - GINT STD US.GDT - 3/16/20Earth Solutions NW, LLC 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 TESTS U.S.C.S.MATERIAL DESCRIPTION GRAPHICLOG 125.5 124.5 120.0 MC = 10.90% MC = 6.60% Fines = 7.80% MC = 45.40% TPSL SM SP- SM Dark brown TOPSOIL -root intrusions to 4' Tan silty SAND, medium dense, moist Gray poorly graded SAND with silt, medium dense, moist [USDA Classification: gravelly SAND] -8" tan silty sand lens -becomes wet Test pit terminated at 8.0 feet below existing grade. No groundwater encountered during excavation. No caving observed. 2.5 3.5 8.0 NOTES Depth of Topsoil & Sod 30": grass GROUND ELEVATION 128 ft LOGGED BY BCS EXCAVATION METHOD TEST PIT SIZE EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS: CHECKED BY KDH DATE STARTED 2/17/20 COMPLETED 2/17/20 AT TIME OF EXCAVATION --- AT END OF EXCAVATION --- AFTER EXCAVATION ---SAMPLE TYPENUMBERDEPTH(ft)0 5 PAGE 1 OF 1 TEST PIT NUMBER TP-5 PROJECT NUMBER ES-7126 PROJECT NAME Meadow Avenue Short Plat GENERAL BH / TP / WELL - 7126.GPJ - GINT STD US.GDT - 3/16/20Earth Solutions NW, LLC 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 TESTS U.S.C.S.MATERIAL DESCRIPTION GRAPHICLOG Earth Solutions NW, LLC Appendix B Laboratory Test Results ES-7126 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 HYDROMETER304 1.4 33.2 8.2 5.1 15.2 101/2 COBBLES Specimen Identification 4 coarse 20 401.5 8 14 USDA: Tan Very Gravelly Coarse Sand. USCS: SP with Gravel. USDA: Tan Slightly Gravelly Very Fine Sandy Loam. USCS: SM. USDA: Gray Slightly Gravelly Sand. USCS: SP-SM. USDA: Gray Gravelly Coarse Sand. USCS: SP-SM with Gravel. USDA: Tan Slightly Gravelly Loamy Sand. USCS: SM. 6 60 PERCENT FINER BY WEIGHTD10 0.526 0.174 0.399 0.111 7.406 0.137 0.259 1.314 0.253 GRAIN SIZE DISTRIBUTION 100 36.98 3.06 8.55 LL TP-01 TP-02 TP-02 TP-02 TP-03 0.2 0.085 0.154 3/4U.S. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS GRAVEL SAND 37.5 9.5 9.5 19 9.5 %Silt 0.19 1.38 0.79 TP-01 TP-02 TP-02 TP-02 TP-03 2 2003 Cc CuClassification %Clay 16 PID60 D30 coarse SILT OR CLAYfinemedium GRAIN SIZE IN MILLIMETERS 3/8 50 5.0ft. 3.5ft. 5.0ft. 8.5ft. 4.0ft. 5.00ft. 3.50ft. 5.00ft. 8.50ft. 4.00ft. PL PROJECT NUMBER ES-7126 PROJECT NAME Meadow Avenue Short Plat GRAIN SIZE USDA ES-7126 MEADOW AVENUE SHORT PLAT.GPJ GINT US LAB.GDT 3/10/20Earth Solutions NW, LLC 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 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 HYDROMETER304 7.8 101/2 COBBLES Specimen Identification 4 coarse 20 401.5 8 14 USDA: Gray Gravelly Sand. USCS: SP-SM. 6 60 PERCENT FINER BY WEIGHTD10 0.2650.664 GRAIN SIZE DISTRIBUTION 100 7.71 LL TP-05 0.086 3/4U.S. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS GRAVEL SAND 19 %Silt 1.23 TP-05 2 2003 Cc CuClassification %Clay 16 PID60 D30 coarse SILT OR CLAYfinemedium GRAIN SIZE IN MILLIMETERS 3/8 50 4.0ft. 4.00ft. PL PROJECT NUMBER ES-7126 PROJECT NAME Meadow Avenue Short Plat GRAIN SIZE USDA ES-7126 MEADOW AVENUE SHORT PLAT.GPJ GINT US LAB.GDT 3/10/20Earth Solutions NW, LLC 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 Earth Solutions NW, LLC Report Distribution ES-7126 EMAIL ONLY Mr. Huy Nguyen 15400 Southeast 155th Place, Unit 99 Renton, Washington 98058