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HomeMy WebLinkAboutRS_Geotechnical_Report_20210521_v1.pdfSECTION 37 GEOTECHNICAL REPORT EarthSolutionsNWLLC EarthSolutions NW LLC 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 UPDATED GEOTECHNICAL ENGINEERING STUDY PROPOSED RENTON APARTMENTS 615 AND 617 WILLIAMS AVENUE SOUTH RENTON, WASHINGTON ES-5946.03 PREPARED FOR GMD DEVELOPMENT, LLC June 10, 2020 _________________________ Adam Z. Shier, L.G. Project Geologist _________________________ Kyle R. Campbell, P.E. Principal Engineer UPDATED GEOTECHNICAL ENGINEERING STUDY PROPOSED RENTON APARTMENTS 615 AND 617 WILLIAMS AVENUE SOUTH RENTON, WASHINGTON ES-5946.03 Earth Solutions NW, LLC 15365 Northeast 90th Street, Suite 100 Redmond, Washington 98052 Phone: 425-449-4704 | Fax: 425-449-4711 www.earthsolutionsnw.com 06/10/2020 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 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 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 June 10, 2020 ES-5946.03 GMD Development, LLC 520 Pike Street, Suite 1010 Seattle, Washington 98101 Attention: Mr. Thomas Geffner Dear Mr. Geffner: Earth Solutions NW, LLC (ESNW) is pleased to present this report titled “Updated Geotechnical Engineering Study, Proposed Renton Apartments, 615 and 617 Williams Avenue South, Renton, Washington”. This report was updated to reference the most current plans and provide additional subsurface exploration. Based on the conditions observed during our fieldwork, the site is underlain primarily by a relatively thick layer of very loose to medium dense alluvial sediments consisting predominately of silt and sand layers. The seasonal groundwater level was observed at depths of about six to nine feet below existing grades. Groundwater levels fluctuate and may become shallower during the wetter winter months. Based on the results of our study, the proposed apartment building should be supported by a pile foundation system advanced through the loose soils to bear on firm native soils, or on conventional shallow foundations after completion of a ground improvement program (rammed aggregate piers, etc.). Recommendations for foundation design and other geotechnical recommendations are provided in this study. 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 Adam Z. Shier, L.G. Project 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-5946.03 PAGE INTRODUCTION ................................................................................. 1 General..................................................................................... 1 Project Description ................................................................. 2 SITE CONDITIONS ............................................................................. 2 Surface ..................................................................................... 2 Subsurface .............................................................................. 2 Groundwater ................................................................. 3 Geologically Hazardous Areas .............................................. 3 Seismic Hazard Areas .................................................. 4 Coal Mine Hazard Areas .............................................. 4 DISCUSSION AND RECOMMENDATIONS ....................................... 4 General..................................................................................... 4 Site Preparation and Earthwork ............................................. 5 Foundations ............................................................................ 6 Ground Improvement ................................................... 6 Pile Foundations .......................................................... 6 Building Slabs ......................................................................... 7 Retaining Walls ....................................................................... 7 Seismic Considerations ......................................................... 8 Drainage................................................................................... 8 Utility Trench Backfill ............................................................. 8 Pavement Sections ................................................................. 9 LIMITATIONS ...................................................................................... 9 Additional Services ................................................................. 9 Earth Solutions NW, LLC Table of Contents Cont’d ES-5946.03 GRAPHICS Plate 1 Vicinity Map Plate 2 Subsurface Exploration Plan Plate 3 Retaining Wall Drainage Detail Plate 4 Footing Drain Detail APPENDICES Appendix A Subsurface Exploration Boring and Test Pit Logs Appendix B Laboratory Test Results Earth Solutions NW, LLC UPDATED GEOTECHNICAL ENGINEERING STUDY PROPOSED RENTON APARTMENTS 615 AND 617 WILLIAMS AVENUE SOUTH RENTON, WASHINGTON ES-5946.03 INTRODUCTION General This updated geotechnical engineering study was prepared for the proposed apartment building to be constructed at 615 and 617 Williams Avenue in Renton, Washington. The purpose of this study was to prepare geotechnical recommendations for the proposed development. Our scope of services for completing this geotechnical engineering study included the following:  Subsurface exploration and laboratory testing of soil samples obtained during subsurface exploration;  Engineering analyses, and;  Preparation of this report. As part of our report preparation, the following documents were reviewed:  Architectural Site Plan, prepared by Studio19 Architects;  Geologic Map of the Renton Quadrangle, King County, Washington, 1965, by D.R. Mullineaux;  Geologic Structure Map of Renton Coal Mine, 1920, by Watkins Evans;  Amendments to the King County Surface Water Design Manual, February 2010, Provided by the City of Renton, and;  The Natural Resources Conservation Service Web Soil Survey (WSS). GMD Development, LLC ES-5946.03 June 10, 2020 Page 2 Earth Solutions NW, LLC Project Description We understand the site will be developed with an apartment building and associated improvements. A preliminary site layout plan was available to us at the time of this report preparation, and we anticipate the building will be six stories in height with one level of concrete and five levels of wood frame supported on a post-tensioned concrete slab. No grading plans were available at the time of writing this report; however, we anticipate the parking area will have a finish floor elevation matching the existing grade. The building will likely incorporate a post- tensioned slab configuration. If grades will be raised more than one foot, the recommendations herein must be re-evaluated by ESNW. We anticipate foundation loads will be on the order of 4 to 6 kips per lineal foot for continuous footings, column loads on the order of 300 to 500 kips and slab-on-grade loading will likely be on the order of 150 pounds per square foot (psf). A preload program to reduce settlement on site will likely be necessary due to the soil conditions encountered. If the above design assumptions are incorrect or change, ESNW should be contacted to review the recommendations in this report. ESNW should review the final design to verify that our geotechnical recommendations have been incorporated. SITE CONDITIONS Surface The site is located at 615 and 617 Williams Avenue in Renton, Washington. The site is irregular in shape and is bordered to the north and west by mixed commercial and residential properties, to the south by South Grady Way and to the east by Williams Avenue South. The 617 address is currently occupied by a billboard, and the 615 address contains a single-family residence. The overall site topography is relatively flat with little discernible elevation change and vegetation consists primarily of field grass with sparse trees near Williams Avenue. The limits of the property are approximately delineated on the Subsurface Exploration Plan (Plate 2). Subsurface Two test pits were excavated across accessible areas of the site for purposes of assessing soil conditions and characterizing the site soils on March 20, 2018. A boring was completed on April 5, 2018 to further classify the site soils. Three additional borings (B-101, B-102, and B-103) were advanced across the subject site on May 22, 2020 as part of this updated geotechnical engineering study. Please refer to the test pit and boring logs provided in Appendix A for a more detailed description of the subsurface conditions. Additionally, two groundwater wells were installed at boring locations B-101 and B-102 to monitor groundwater throughout the 2020-2021 winter season. GMD Development, LLC ES-5946.03 June 10, 2020 Page 3 Earth Solutions NW, LLC At our test sites, a relatively deep topsoil layer was encountered extending up to about two feet below existing grades. The topsoil was characterized by a dark brown color and organic content. fill was not encountered; however, fill may be present in areas where former structures were removed. Underlying the topsoil, very loose to medium dense alluvial and floodplain deposits consisting of non-plastic silt (ML), silty fine sand (SM) and sand (SP, SP-SM) were encountered extending to the maximum exploration depth of 46.5 feet. A thin layer of peat (PT) was encountered at boring location B-1 and B-101 from about 21 to 21.5 feet below existing grade. Soil conditions improved to a medium dense state at depths of about 20 to 30 feet. The referenced geologic map of the area identifies alluvial soil deposits modified by widespread artificial fill throughout the site and surrounding areas. The referenced WSS resource indicates the site is underlain predominantly by Urban land (Ur) soils. This soil unit is used in areas of extensive grading. The soil conditions observed at our test sites generally correlates with historic fill underlain by alluvial deposition. Groundwater The seasonal groundwater table was observed at an average depth of about six to nine feet below existing grades during our fieldwork (March and April 2018) which occurred during a record rainfall season and between 9 to 10 feet during our May 2020 fieldwork. However, the seasonal high groundwater elevation may rise to a shallower depth than the elevation observed during our fieldwork depending on the seasonal rainfall. It should be noted that groundwater elevations fluctuate depending on many factors, including precipitation duration and intensity, the time of year, and soil conditions. In general, groundwater levels are generally higher during the wetter, winter months. With respect to the proposed development activities, groundwater should be expected in site excavations, particularly underground utility and vault excavations. We understand underground building levels are not planned as part of the proposed construction. In this respect, extensive measures for controlling groundwater and temporary dewatering are not anticipated. However, temporary dewatering of underground utility excavations should be expected throughout some areas of the site. Flowing sand condition may be encountered depending on the time of year deeper excavations occur. Additionally, two groundwater wells were installed at boring locations B-101 and B-102 to monitor groundwater throughout the 2020-2021 winter season. Geologically Hazardous Areas As part of this study, the site and proposed development areas were evaluated for the presence of geologically hazardous areas. As part of our evaluation, Chapter 4-3-050 of the Renton Municipal Code was reviewed. GMD Development, LLC ES-5946.03 June 10, 2020 Page 4 Earth Solutions NW, LLC Seismic Hazard Areas Liquefaction is a phenomenon where saturated or loose soils suddenly lose internal strength in response to increased pore water pressures resulting from an earthquake or other intense ground shaking. The liquefaction susceptibility for the subject site in the current configuration is high. We used the Liquefy5 computer program to assess the overall susceptibility of the site to liquefaction and associated settlement resulting from the maximum credible earthquake event for this area. We determined the peak ground acceleration (PGA) using the USGS online calculation program that provides current information for a particular address location. Using this resource, a design PGA of 0.4g was used. The computer model predicted significant settlement may occur from liquefaction occurring after the site is subjected to the design PGA. We used this assessment to aid in developing foundation support recommendations that would adequately mitigate differential settlement and maintain adequate levels of life-safety subsequent to a design earthquake event. We would expect total settlements in the range of five to ten inches and differential settlements of between two to four inches may result from strong seismic shaking to occur within the existing soils. Providing a uniform subgrade and foundation support using either piles or a ground improvement program will reduce the potential for differential settlement that may result from a strong seismic event. With foundation support as recommended in this report, we do not anticipate life-safety will be compromised resulting from liquefaction; however, damage should be expected from seismic shaking. Coal Mine Hazard Areas We reviewed the referenced coal mine hazard mapping collection to classify existing coal mine hazard areas on the site in general accordance with chapter 4-3-050 of the Renton Municipal Code. Based on our document review, it appears that a mine opening located southwest of the subject property was likely used as an access-way which trended south toward seam workings. The mine entrance is located southwest of Parcel Number 172305-9069, and is not present on the property. Based on the reviewed information, the site should be considered a “Declassified” coal mine hazard because no records of coal mine activity are present on or within 500 feet of the identified mine opening. The risk of subsidence or related damage associated with coal mine hazards does not exist on this site. DISCUSSION AND RECOMMENDATIONS General Based on the results of our updated study, construction of the proposed apartment building is feasible from a geotechnical standpoint. The primary geotechnical considerations associated with the proposed development include foundation support, minimizing post-construction settlements, structural fill placement, and the suitability of the on-site soils for use as structural fill. GMD Development, LLC ES-5946.03 June 10, 2020 Page 5 Earth Solutions NW, LLC The proposed apartment building should be supported by a pile foundation system advanced through the loose soils to bear on firm native soils, or on conventional shallow foundations after completion of a ground improvement program (rammed aggregate piers, etc.). The presence of groundwater in excavations that extend below about six to nine feet should be anticipated. The groundwater table will likely fluctuate throughout the year, depending on many factors and may rise above the depth where it was observed during the fieldwork. Appropriate de-watering measures should be incorporated into site designs prior to construction. ESNW should review final site layout and plans to confirm the geotechnical recommendations in this report have been incorporated into the plans and to provide supplemental recommendations, as appropriate. This study has been prepared for the exclusive use of the GMD Development, LLC and their representatives. No warranty, expressed or implied, is made. 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 With respect to earthwork, the primary considerations at this site are related to structural fill compaction, moisture sensitivity of the site soils, and foundation support. From a geotechnical standpoint, the soils encountered at the test sites may not be suitable for use as structural fill depending on the moisture content at the time of grading. Successful use of the on-site soils will largely be dictated by the moisture content of the soils at the time of placement and compaction. The soils encountered at the test sites above the groundwater table were generally in a moist to wet condition at the time of the exploration (March and April 2018). Soils encountered during site excavations that are excessively over the optimum moisture content may require moisture conditioning prior to placement and compaction. Successful placement and compaction of the on-site soils during periods of extended precipitation will likely be difficult. If the on-site soils cannot be successfully compacted, the use of an imported soil may be necessary. Imported soil intended for use as structural fill should consist of a well graded granular soil with a moisture content that is at or near the optimum level. 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 defined as the percent passing the #200 sieve, based on the minus three-quarter inch fraction. Structural fill is defined as compacted soil placed in foundation, slab-on-grade, and roadway areas. Fills placed to construct permanent slopes and throughout retaining wall and utility trench backfill areas are also considered structural fill. Soils placed in structural areas should be compacted to a relative compaction of 95 percent, based on the maximum dry density as determined by the Modified Proctor Method (ASTM D-1557) and placed in maximum 12 inch lifts. Temporary construction entrances and drive lanes, consisting of at least 12 inches of quarry spalls can be considered in order to minimize off-site soil tracking and to provide a relatively firm temporary road surface. Erosion control measures should consist of silt fencing and surface water runoff controls. GMD Development, LLC ES-5946.03 June 10, 2020 Page 6 Earth Solutions NW, LLC Foundations The soils underlying this site are relatively weak and contain compressible layers. Groundwater was observed at a depth of about six to nine feet below existing grade. Foundations must be designed to reduce the effects of liquefaction-induced settlement and provide adequate static support for the new building. Based on the results of our study and our understanding of the project, the proposed apartment building should be supported by a pile foundation system advanced through the loose soils to bear on firm native soils, or on conventional shallow foundations after completion of a ground improvement program (rammed aggregate piers, etc.). Differential settlement between pile and non-pile supported elements will occur. Ground Improvement Rammed aggregate piers (RAPs) stone columns or other vibro-installation intermediate elements can be considered as ground-improvement for foundation support. Vibro-installed elements provide ground improvement between elements, essentially providing ground improvement over a uniform area. This method provides increased resistance to liquefaction-induced settlement and would immediately improve the surrounding soil where installed. For preliminary design considerations, we recommend ground improvement elements be installed to a minimum depth of 40 feet. ESNW should review proposed designs to confirm the soil parameters used are representative of the site conditions. For preliminary considerations, foundations supported by ground improvement elements can be designed 4,000 pounds per square foot (psf) of allowable bearing capacity. Pile Foundations If piles will be pursued for foundation support, we provide capacities for 18 inch diameter augercast piles. Other pile diameters can also be considered, and should be assessed by ESNW. The following allowable capacities for 18 inch diameter augercast piles should be used for foundation design. Allowable Capacities * Allowable uplift capacity does not include weight of the pile or pier. The above allowable capacity is based on a pile length of 40 feet to bear within the medium dense to dense soil deposits. A higher pile capacity is possible, however, an additional boring would be necessary to confirm soil conditions at depth. A representative of ESNW should observe the installation of the foundations and assess pile foundation lengths based on the soil conditions encountered during the installation. Lateral Capacities Diameter (in.) Compression (kps) Uplift (kps)* 0.5 Inch (kips) Deflection 1.0 Inch (kips) Deflection 18 100 55 10 16 GMD Development, LLC ES-5946.03 June 10, 2020 Page 7 Earth Solutions NW, LLC Building Slabs Building slabs should be structurally supported by the pile foundation system if piles are used. If the ground improvement option is used for foundation support, building slabs can be supported on grade provided ground improvement program includes slab areas. 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 five percent or less (percent passing the #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. Retaining Walls If retaining walls will be used for this project, they should be designed to resist earth pressures and applicable surcharge loads. For design, the following parameters can be assumed for retaining wall design:  Active earth pressure (yielding condition) 35 pcf (equivalent fluid)  At-rest earth pressure (restrained condition) 55 pcf  Traffic surcharge (passenger vehicles) 70 psf (rectangular distributio n)*  Passive earth pressure 300 pcf (equivalent fluid)  Coefficient of friction 0.40  Seismic surcharge 8H psf** * Where applicable ** Where H equals the retained height (in feet) Additional surcharge loading from foundations, sloped backfill, or other loading 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. 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 one foot of the wall backfill can consist of a less permeable soil, if desired. A perforated drain pipe should be placed along the base of the wall, and connected to an appropriate discharge location. GMD Development, LLC ES-5946.03 June 10, 2020 Page 8 Earth Solutions NW, LLC Seismic Considerations The 2015 IBC recognizes ASCE for seismic site class definitions. If the project will be permitted under the 2015 IBC, in accordance with Table 20.3-1 of ASCE, Minimum Design Loads for Buildings and Other Structures, Site Class E, should be used for design. In our opinion, liquefaction susceptibility at this site is high due to the soil gradation and groundwater conditions. Foundations must be designed to resist or reduce the effects of liquefaction-induced settlement, which can be mitigated using either ground improvement or piles, as discussed earlier in this report. Drainage The seasonal groundwater table was observed at an average depth of approximately six to nine feet below existing grades during our fieldwork (March and April 2018). As such, the presence of groundwater should be expected in deeper site excavations, such as those required for utility improvements or detention vault areas. Temporary measures to control groundwater seepage and surface water runoff during construction will likely involve interceptor trenches and sumps, as necessary. Where heavy seepage conditions are encountered, particularly in deeper excavations, conventional dewatering methods such as pumping wells or well points may be necessary. Perimeter drains should be installed below the invert of foundations or pile caps and grade beams. A typical perimeter drain detail is provided on Plate 3. Utility Trench Backfill In our opinion, the soils observed at the test sites are not suitable for direct support of utilities in the current condition and will require stabilization prior to installing utilities. Moderate to heavy caving of the site soils should be expected during deeper site excavations. Means of shoring or sloping excavation walls should be accounted for prior to construction. Organic or highly compressible soils encountered in the trench excavations should not be used for supporting utilities. Subgrade stabilization will likely be required and may consist of quarry spalls placed over a woven geotextile such as Mirafi 500X or approved alternative. In general, the on-site soils observed at the test sites are not suitable for use as structural backfill in the utility trench excavations due to the predominately fine-grained texture. Moisture conditioning 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 specifications of the city or county jurisdictions, as appropriate. GMD Development, LLC ES-5946.03 June 10, 2020 Page 9 Earth Solutions NW, LLC 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 proofrolling with a loaded dump truck. Structural fill in pavement areas should be compacted to the specifications detailed in the Site Preparation and Earthwork section of this report. It is possible that soft, wet, or otherwise unsuitable subgrade areas may still exist after base grading activities. Areas containing unsuitable or yielding subgrade conditions may require remedial measures such as overexcavation and thicker crushed rock or structural fill sections prior to pavement. Cement treatment of the subgrade soil can also be considered for stabilizing pavement subgrade areas if allowed by local jurisdictions. For relatively lightly loaded pavements subjected to automobiles and occasional truck traffic, the following sections can be considered:  Two inches of asphalt concrete (AC) placed over four inches of crushed rock base (CRB), or;  Two inches of AC placed over three inches of asphalt treated base (ATB). Heavier traffic areas generally require thicker pavement sections depending on site usage, pavement life expectancy, and site traffic. For preliminary design purposes, the following pavement sections for occasional truck traffic areas can be considered:  Three inches of asphalt concrete (AC) placed over six inches of crushed rock base (CRB), or;  Three inches of AC placed over four and one-half inches of asphalt treated base (ATB). The AC, ATB and CRB materials should conform to WSDOT specifications. ESNW can provide appropriate pavement section design recommendations for truck traffic areas and right-of-way improvements, as necessary. Additionally, the City of Renton Pavement Design Standards may supersede the recommendations provided in this report. LIMITATIONS The recommendations and conclusions provided in this 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 pit and boring locations may exist, and may not become evident until construction. ESNW should reevaluate the conclusions 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 provide testing and consultation services during construction. Geotechnical Engineering,Construction Observation/Testing and Environmental Services Drwn. CAM Checked AZS Date June 2020 Date 06/09/2020 Proj. No. 5946.03 Plate 1 Earth Solutions NWLLCEarthSolutionsNWLLC EarthSolutions NW LLC Vicinity Map Renton Apartments 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. Renton SITE Plate Proj. No. Date Checked By Drwn. ByEarth Solutions NWLLCGeotechnical Engineering,ConstructionObservation/Testing and Environmental ServicesEarthSolutionsNWLLCEarthSolutionsNWLLCss..ggrr aadd yyww aayywwiilllliiaammssaavveennuueess..TP-1 TP-2 B-1 B-101 B-102 B-103 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 Boring, Proj. No. ES-5946.03, May 2020 Approximate Location of ESNW Boring, Proj. No. ES-5946, April 2018 Approximate Location of ESNW Test Pit, Proj. No. ES-5946, March 2018 Subject Site Proposed Building Existing Building TP-1 NOT - TO - SCALE NORTH Subsurface Exploration PlanRenton ApartmentsRenton, Washington B-101 B-1 CAM AZS 06/09/2020 5946.03 2 Drwn. CAM Checked AZS Date June 2020 Date 06/09/2020 Proj. No. 5946.03 Plate 3 Earth Solutions NWLLCEarthSolutionsNWLLC EarthSolutions NW LLC Geotechnical Engineering,Construction Observation/Testing and Environmental Services Retaining Wall Drainage Detail Renton Apartments 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. CAM Checked AZS Date June 2020 Date 06/09/2020 Proj. No. 5946.03 Plate 4 Earth Solutions NWLLCEarthSolutionsNWLLC EarthSolutions NW LLC Geotechnical Engineering,Construction Observation/Testing and Environmental Services Footing Drain Detail Renton Apartments 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 Boring and Test Pit Logs ES-5946.03 The subsurface conditions at the site were explored by excavation two test pits and drilling four boring. The approximate exploration locations are illustrated on Plate 2 of this report. The logs are provided in this Appendix. The subsurface exploration was completed in March and April 2018 and May 2020. The boring was excavated to a maximum depth of 46.5 feet below existing grades. Logs of the borings excavated by ESNW are presented in Appendix A. 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 GRAVELLY SOILS CLAYEY GRAVELS, GRAVEL - SAND - CLAY MIXTURES WELL-GRADED SANDS, GRAVELLY SANDS, LITTLE OR NO FINES POORLY-GRADED SANDS, GRAVELLY SAND, LITTLE OR NO FINES SILTY SANDS, SAND - SILT MIXTURES CLAYEY SANDS, SAND - CLAY MIXTURES INORGANIC SILTS AND VERY FINE SANDS, ROCK FLOUR, SILTY OR CLAYEY FINE SANDS OR CLAYEY SILTS WITH SLIGHT PLASTICITY INORGANIC CLAYS OF LOW TO MEDIUM PLASTICITY, GRAVELLY CLAYS, SANDY CLAYS, SILTY CLAYS, LEAN CLAYS ORGANIC SILTS AND ORGANIC SILTY CLAYS OF LOW PLASTICITY INORGANIC SILTS, MICACEOUS OR DIATOMACEOUS FINE SAND OR SILTY SOILS INORGANIC CLAYS OF HIGH PLASTICITY SILTS AND CLAYS MORE THAN 50% OF MATERIAL IS LARGER THAN NO. 200 SIEVE SIZE MORE THAN 50% OF MATERIAL IS SMALLER THAN NO. 200 SIEVE SIZE MORE THAN 50% OF COARSE FRACTION PASSING ON NO. 4 SIEVE MORE THAN 50% OF COARSE FRACTION RETAINED ON NO. 4 SIEVE SOIL CLASSIFICATION CHART (APPRECIABLE AMOUNT OF FINES) (APPRECIABLE AMOUNT OF FINES) (LITTLE OR NO FINES) FINE GRAINED SOILS SAND AND SANDY SOILS SILTS AND CLAYS ORGANIC CLAYS OF MEDIUM TO HIGH PLASTICITY, ORGANIC SILTS PEAT, HUMUS, SWAMP SOILS WITH HIGH ORGANIC CONTENTS LETTERGRAPH SYMBOLSMAJOR DIVISIONS COARSE GRAINED SOILS TYPICAL DESCRIPTIONS WELL-GRADED GRAVELS, GRAVEL - SAND MIXTURES, LITTLE OR NO FINES POORLY-GRADED GRAVELS, GRAVEL - SAND MIXTURES, LITTLE OR NO FINES SILTY GRAVELS, GRAVEL - SAND - SILT MIXTURES CLEAN GRAVELS GRAVELS WITH FINES CLEAN SANDS (LITTLE OR NO FINES) SANDS WITH FINES LIQUID LIMIT LESS THAN 50 LIQUID LIMIT GREATER 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 SS SS SS SS SS 33 33 50 50 67 2-2-2 (4) 1-2-2 (4) 1-1-1 (2) 1-6-1 (7) 2-2-2 (4) MC = 26.40% MC = 30.30% MC = 58.40% MC = 41.20% Fines = 68.20% MC = 30.10% SM ML SM Brown silty SAND, very loose, moist Gray sandy SILT, very loose, moist to wet [USDA Classification: LOAM] Gray silty SAND, very loose, wet -groundwater table 6.0 13.0 NOTES Surface Conditions: field grass GROUND ELEVATION LOGGED BY AZS DRILLING METHOD HSA HOLE SIZE DRILLING CONTRACTOR Boretec1, Inc.GROUND WATER LEVELS: CHECKED BY KRC DATE STARTED 5/22/20 COMPLETED 5/22/20 AT END OF DRILLING --- AFTER DRILLING --- AT TIME OF 14.5 ft (Continued Next Page)SAMPLE TYPENUMBERDEPTH(ft)0 5 10 15 20 PAGE 1 OF 3 BORING NUMBER B-101 PROJECT NUMBER ES-5946.03 PROJECT NAME Renton Apartments GENERAL BH / TP / WELL - 5946-3.GPJ - GRAPHICS TEMPLATE.GDT - 6/10/20Earth 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 GRAPHICLOG SS SS SS SS SS 100 100 100 100 100 1-2-2 (4) 2-3-2 (5) 5-3-8 (11) 7-11-11 (22) 8-15-11 (26) MC = 35.10% MC = 108.90% MC = 24.60% MC = 11.90% MC = 9.50% MC = 15.80% Fines = 4.10% SM SP Gray silty SAND, very loose, wet (continued) -1"-2" sand lens -6" organic lens (peat) Gray poorly graded SAND, loose, wet -trace organics -becomes poorly graded sand with gravel -becomes medium dense [USDA Classification: gravelly coarse SAND] 25.0 42.9 (Continued Next Page)SAMPLE TYPENUMBERDEPTH(ft)20 25 30 35 40 PAGE 2 OF 3 BORING NUMBER B-101 PROJECT NUMBER ES-5946.03 PROJECT NAME Renton Apartments GENERAL BH / TP / WELL - 5946-3.GPJ - GRAPHICS TEMPLATE.GDT - 6/10/20Earth 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 GRAPHICLOG SS 100 9-8-10 (18)MC = 23.90% SP Gray poorly graded SAND with gravel, medium dense, wet (continued) Boring terminated at 46.5 feet below existing grade. Groundwater table encountered at 14.5 feet during drilling. 2" PVC standpipe installed to bottom of boring. Lower 20.0 feet slotted. Well ID: BJZ554. Boring backfilled with bentonite/sand. 46.5SAMPLE TYPENUMBERDEPTH(ft)45 PAGE 3 OF 3 BORING NUMBER B-101 PROJECT NUMBER ES-5946.03 PROJECT NAME Renton Apartments GENERAL BH / TP / WELL - 5946-3.GPJ - GRAPHICS TEMPLATE.GDT - 6/10/20Earth 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 GRAPHICLOG SS SS SS SS SS 33 50 33 50 67 2-2-1 (3) 1-1-0 (1) 1-1-1 (2) 1-0-1 (1) 1-1-0 (1) MC = 13.30% MC = 43.60% MC = 82.30% MC = 37.30% MC = 92.90% SM ML Brown silty SAND, very loose, moist Gray SILT, very loose, wet -wood debris -wood debris -groundwater table 4.5 NOTES Surface Conditions: grass GROUND ELEVATION LOGGED BY AZS DRILLING METHOD HSA HOLE SIZE DRILLING CONTRACTOR Boretec1, Inc.GROUND WATER LEVELS: CHECKED BY KRC DATE STARTED 5/22/20 COMPLETED 5/22/20 AT END OF DRILLING --- AFTER DRILLING --- AT TIME OF 13.0 ft (Continued Next Page)SAMPLE TYPENUMBERDEPTH(ft)0 5 10 15 20 PAGE 1 OF 3 BORING NUMBER B-102 PROJECT NUMBER ES-5946.03 PROJECT NAME Renton Apartments GENERAL BH / TP / WELL - 5946-3.GPJ - GRAPHICS TEMPLATE.GDT - 6/10/20Earth 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 GRAPHICLOG SS SS SS SS SS 100 100 100 100 100 2-2-4 (6) 2-4-9 (13) 4-6-5 (11) 2-4-4 (8) 3-4-6 (10) MC = 30.00% MC = 16.90% Fines = 4.10% MC = 26.90% MC = 18.30% MC = 20.70% ML SP- SM SP Gray SILT, very loose, wet (continued) Gray poorly graded SAND with silt, loose, wet/saturated [USDA Classification: very gravelly coarse SAND] Gray poorly graded SAND with gravel, medium dense, wet/saturated -becomes loose -becomes medium dense 20.5 25.5 (Continued Next Page)SAMPLE TYPENUMBERDEPTH(ft)20 25 30 35 40 PAGE 2 OF 3 BORING NUMBER B-102 PROJECT NUMBER ES-5946.03 PROJECT NAME Renton Apartments GENERAL BH / TP / WELL - 5946-3.GPJ - GRAPHICS TEMPLATE.GDT - 6/10/20Earth 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 GRAPHICLOG SS 100 5-5-7 (12)MC = 16.20% SP Gray poorly graded SAND with gravel, medium dense, wet/saturated (continued) Boring terminated at 46.5 feet below existing grade. Groundwater table encountered at 13.0 feet during drilling. 2" PVC standpipe installed to bottom of boring. Lower 20.0 feet slotted. Well ID: BJZ555. Boring backfilled with bentonite/sand. 46.5SAMPLE TYPENUMBERDEPTH(ft)45 PAGE 3 OF 3 BORING NUMBER B-102 PROJECT NUMBER ES-5946.03 PROJECT NAME Renton Apartments GENERAL BH / TP / WELL - 5946-3.GPJ - GRAPHICS TEMPLATE.GDT - 6/10/20Earth 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 GRAPHICLOG SS SS SS SS SS 33 67 50 100 2-1-0 (1) 1-1-0 (1) 1-1-1 (2) 2-5-7 (12) 2-2-2 (4) MC = 38.70% MC = 38.00% MC = 77.20% MC = 40.40% Fines = 64.40% MC = 27.50% ML SP Brown sandy SILT, very loose, moist to wet -wood debris -becomes gray -wood debris [USDA Classification: LOAM] Gray poorly graded SAND, very loose, wet -groundwater table 13.0 NOTES Surface Conditions: grass GROUND ELEVATION LOGGED BY AZS DRILLING METHOD HSA HOLE SIZE DRILLING CONTRACTOR Boretec1, Inc.GROUND WATER LEVELS: CHECKED BY KRC DATE STARTED 5/22/20 COMPLETED 5/22/20 AT END OF DRILLING --- AFTER DRILLING --- AT TIME OF 13.5 ft (Continued Next Page)SAMPLE TYPENUMBERDEPTH(ft)0 5 10 15 20 PAGE 1 OF 3 BORING NUMBER B-103 PROJECT NUMBER ES-5946.03 PROJECT NAME Renton Apartments GENERAL BH / TP / WELL - 5946-3.GPJ - GRAPHICS TEMPLATE.GDT - 6/10/20Earth 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 GRAPHICLOG SS SS SS SS SS 100 100 100 100 100 2-2-1 (3) 4-5-9 (14) 4-4-3 (7) 2-3-3 (6) 4-6-6 (12) MC = 14.50% MC = 23.50% MC = 19.00% MC = 34.20% MC = 24.00% SP ML SM Gray poorly graded SAND, very loose, wet (continued) -4" silt lens -becomes loose Gray SILT, loose, wet Gray silty SAND, medium dense, wet 35.0 38.0 (Continued Next Page)SAMPLE TYPENUMBERDEPTH(ft)20 25 30 35 40 PAGE 2 OF 3 BORING NUMBER B-103 PROJECT NUMBER ES-5946.03 PROJECT NAME Renton Apartments GENERAL BH / TP / WELL - 5946-3.GPJ - GRAPHICS TEMPLATE.GDT - 6/10/20Earth 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 GRAPHICLOG SS 9-15-10 (25)MC = 21.90% SM Gray silty SAND, medium dense, wet (continued) Boring terminated at 46.5 feet below existing grade. Groundwater table encountered at 13.5 feet during drilling. Boring backfilled with bentonite. 46.5SAMPLE TYPENUMBERDEPTH(ft)45 PAGE 3 OF 3 BORING NUMBER B-103 PROJECT NUMBER ES-5946.03 PROJECT NAME Renton Apartments GENERAL BH / TP / WELL - 5946-3.GPJ - GRAPHICS TEMPLATE.GDT - 6/10/20Earth 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 GRAPHICLOG SS SS SS SS SS 22 94 78 100 67 6-4-3 (7) 1-1-1 (2) 3-3-3 (6) 1-1-1 (2) 2-3-4 (7) MC = 38.10% MC = 31.60% MC = 28.90% MC = 28.70% MC = 30.50% SM TPSL SM SM SP- SM ML 1.0 1.5 3.5 8.0 15.5 Brown silty SAND, loose, damp (Fill) TOPSOIL (Fill) Brown silty SAND, loose, damp (Fill) Brown silty SAND, very loose, wet Gray poorly graded SAND with silt, loose, wet -groundwater seepage at 9' -becomes very loose Gray SILT with sand, loose, wet NOTES GROUND ELEVATION LOGGED BY SES DRILLING METHOD HSA HOLE SIZE DRILLING CONTRACTOR Holocene Drilling GROUND WATER LEVELS: CHECKED BY SSR DATE STARTED 4/5/18 COMPLETED 4/5/18 AT TIME OF DRILLING --- AT END OF DRILLING --- AFTER DRILLING --- (Continued Next Page)SAMPLE TYPENUMBERDEPTH(ft)0 5 10 15 20 PAGE 1 OF 2 BORING NUMBER B-1 PROJECT NUMBER ES-5946 PROJECT NAME Renton Mixed-Use GENERAL BH / TP / WELL - 5946.GPJ - GINT STD US.GDT - 6/10/20Earth 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 GRAPHICLOG SS SS 100 100 3-5-9 (14) 7-10-16 (26) MC = 64.10% Fines = 98.80% MC = 196.00% MC = 38.10% Fines = 56.60% ML PT ML 21.0 21.5 26.5 Gray SILT with sand, loose, wet (continued) [USDA Classification: LOAM] PEAT, wood debris Gray SILT with sand, medium dense, wet [USDA Classification: LOAM] Boring terminated at 26.5 feet below existing grade. Groundwater seepage encountered at 9.0 feet during drilling. Boring backfilled with bentonite.SAMPLE TYPENUMBERDEPTH(ft)20 25 PAGE 2 OF 2 BORING NUMBER B-1 PROJECT NUMBER ES-5946 PROJECT NAME Renton Mixed-Use GENERAL BH / TP / WELL - 5946.GPJ - GINT STD US.GDT - 6/10/20Earth 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 GRAPHICLOG MC = 15.00% MC = 26.60% Fines = 12.80% MC = 35.80% Fines = 52.50% MC = 63.70% SM SP- SM ML Dark brown silty SAND, medium dense, damp (Fill) -large debris Brown poorly graded SAND with silt, dense, moist Gray SILT with sand, dense, wet -caving from 5.5' to BOH [USDA Classification: LOAM] -groundwater table at 7' Test pit terminated at 9.0 feet below existing grade. Groundwater table encountered at 7.0 feet during excavation. Caving observed from 5.5 feet to BOH. 3.5 5.5 9.0 NOTES Surface Conditions: grass GROUND ELEVATION LOGGED BY SES EXCAVATION METHOD TEST PIT SIZE EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS: CHECKED BY SSR DATE STARTED 3/20/18 COMPLETED 3/20/18 AT END OF EXCAVATION --- AFTER EXCAVATION --- AT TIME OF 7.0 ft SAMPLE TYPENUMBERDEPTH(ft)0 5 PAGE 1 OF 1 TEST PIT NUMBER TP-1 PROJECT NUMBER ES-5946 PROJECT NAME Renton Mixed-Use GENERAL BH / TP / WELL - 5946.GPJ - GRAPHICS TEMPLATE.GDT - 6/10/20Earth 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 MC = 23.30% Fines = 58.40% MC = 25.50% MC = 42.70% Fines = 46.50% MC = 27.50% SM ML SM Brown silty SAND, medium dense, damp (Fill) Brown SILT with sand, medium dense, moist Black silty SAND, dense, wet -groundwater table at 6' -bedded with ML Test pit terminated at 7.0 feet below existing grade. Groundwater table encountered at 6.0 feet during excavation. No caving observed. 2.0 5.0 7.0 NOTES GROUND ELEVATION LOGGED BY SES EXCAVATION METHOD TEST PIT SIZE EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS: CHECKED BY SSR DATE STARTED 3/20/18 COMPLETED 3/20/18 AT END OF EXCAVATION --- AFTER EXCAVATION --- AT TIME OF 6.0 ft SAMPLE TYPENUMBERDEPTH(ft)0 5 PAGE 1 OF 1 TEST PIT NUMBER TP-2 PROJECT NUMBER ES-5946 PROJECT NAME Renton Mixed-Use GENERAL BH / TP / WELL - 5946.GPJ - GRAPHICS TEMPLATE.GDT - 6/10/20Earth 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-5946.03 Earth Solutions NW, LLC Report Distribution ES-5946.03 EMAIL COPY GMD Development, LLC 520 Pike Street, Suite 1010 Seattle, Washington 98101 Attention: Mr. Thomas Geffner