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REV 1 REVIEWED PLN_BLD2022-0199+Geotech Report+5.17.2022_9.56.56_PM+2877041REVISION May 18 2022 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT BLD2022-0199 Geotechnical Engineering Construction Observation/Testing Environmental Services GEOTECHNICAL ENGINEERING STUDY MAGRINO-D'SOUZA SINGLE-FAMILY RESIDENCE 16900 TALBOT ROAD EDMONDS, WASHINGTON •- `'_ ES-8338 15365 N -E. 90thtreet,uite 400 �ec#mR9n�`��Q `�_• ' (425) 449-4704 F'(?K5) 449=471 — + Ni wk.QartFi-sd1tltio4spw:c=4 �- - �- PREPARED FOR MR. ROBERT MAGRINO AND MS. BERNADETTE D'SOUZA March 23, 2022 Stephen H. Avril Project Manager CA4P �E WAsh/Nco` %��• �"FGISTER�-" SSIONALE: 03/23/2022 Kyle R. Campbell, P.E. Principal Engineer GEOTECHNICAL ENGINEERING STUDY MAGRINO-D'SOUZA SINGLE-FAMILY RESIDENCE 16900 TALBOT ROAD EDMONDS, WASHINGTON ES-8338 Earth Solutions NW, LLC 15365 Northeast 90t" Street, Suite 100 Redmond, Washington 98052 Phone: 425-449-4704 1 Fax: 425-449-4711 www.earthsolutionsnw.com Geotechnical-Engineering Report 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. GEOPROFESSIONAL BUSINESS SEA ASSOCIATION Telephone: 301 /565-2733 e-mail: info@geoprofessional.org www.geoprofessional.org 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 GBM 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. March 23, 2022 ES-8338 Mr. Robert Magrino and Ms. Bernadette D'Souza 11913 Marine View Drive Edmonds, Washington 98026 Dear Mr. Magrino and Ms. D'Souza: Earth Solutions NWLLC Earth Solutions NW LLC Geotechnical Engineering, Construction Observation/Testing and Environmental Services Earth Solutions NW, LLC (ESNW) is pleased to present this report titled "Geotechnical Engineering Study, 16900 Talbot Road, Edmonds, Washington". The native soil underlying the site consists of Whidbey Formation Pre -Glaciation deposits based on our observation of the subsurface conditions. In our opinion, the proposed pool and deck to be located on the southwest corner of the existing residence can be supported on competent native soils, competent existing fill, or new structural fill. We anticipate suitable bearing soils will be encountered at the proposed depths of approximately one foot (and deeper) below existing grades. Where loose or unsuitable soil conditions are exposed at foundation (and bottom of pool) subgrade elevations, compaction of the soils to the specifications of structural fill, or overexcavation and replacement with a suitable structural fill material will be necessary. Groundwater seepage was not observed during our fieldwork (January 17, 2022). The maximum depth -of -exploration was 56.5 feet below the existing surface elevations. Recommendations for foundation design, site preparation, drainage, and other pertinent recommendations are provided in this study. We appreciate the opportunity to be of service to you on this project. If you have questions regarding the content of this geotechnical engineering study, please call. Sincerely, EARTH SOLUTIONS NW, LLC Stephen H. Avril Project Manager 15365 N.E. 90th Street, Suite 100 • Redmond, WA 98052 • (425) 449-4704 • FAX (425) 449-4711 Table of Contents ES-8338 PAGE INTRODUCTION................................................................................. General.................................................................................... Project Description................................................................. SITE CONDITIONS............................................................................. 2 Surface..................................................................................... 2 Subsurface.............................................................................. 2 Topsoil.......................................................................... 2 Fill.................................................................................. 2 NativeSoil..................................................................... 3 Geologic Setting........................................................... 3 Groundwater................................................................. 3 ENVIRONMENTALLY CRITICAL AREA ASSESSMENT .................. 3 DISCUSSION AND RECOMMENDATIONS ....................................... 6 General.................................................................................... 6 Site Preparation and Earthwork ............................................. 7 In -situ Soils................................................................... 8 ImportedSoils.............................................................. 8 Structural Fill................................................................ 8 Foundations............................................................................ 8 Seismic Design Considerations ............................................ 9 Slab -On -Grade Floors............................................................. 10 RetainingWalls....................................................................... 10 Drainage................................................................................... 11 Excavations and Slopes......................................................... 11 Utility Support and Trench Backfill....................................... 12 LIMITATIONS...................................................................................... 12 Additional Services................................................................. 12 Earth Solutions NW. LLC Table of Contents Cont'd ES-8338 GRAPHICS Plate 1 Vicinity Map Plate 2 Boring Location Plan Plate 3 Retaining Wall Drainage Detail Plate 4 Footing Drain Detail APPENDICES Appendix A Subsurface Exploration Boring Logs Appendix B Laboratory Test Results Appendix C SlopeW Output Earth Solutions NW. LLC GEOTECHNICAL ENGINEERING STUDY MAGRINO-D'SOUZA SINGLE-FAMILY RESIDENCE 16900 TALBOT ROAD EDMONDS, WASHINGTON ES-8338 INTRODUCTION General The project area consists of a site located on the west side of Talbot Road, north of the intersection with 171st Street Southwest in Edmonds, Washington. Site development plans include the construction of a pool and deck on the south side of the existing residence, which sits atop the bluff descending towards the west. The purpose of this study was to explore subsurface conditions across the site and develop geotechnical recommendations for the proposed construction. Additionally, the proposed total setback from top -of -slope for the pool and deck was evaluated from a slope stability standpoint. Our scope of services for completing this geotechnical engineering study included the following: • Site exploration consisting of borings advanced within two locations on the property; • Laboratory testing of soil samples obtained during subsurface exploration; • Engineering analyses of data gathered during site exploration, and; • Preparation of this report. The following documents/maps were reviewed as part of our report preparation: • Geologic Map of Washington, Northwest Quadrant, Dragovich, Logan, et al, 2002; • Client provided site plan, and; • Washington USDA Soil Conservation Survey (SCS). Project Description We understand a pool is planned for the southern side of the existing residence along with a deck located to the west of the proposed pool. The pool is proposed to be four and one-half feet in depth. Earth Solutions NW. LLC Mr. Robert Magrino and Ms. Bernadette D'Souza ES-8338 March 23, 2022 Page 2 Deck construction is anticipated to consist of relatively lightly loaded wood framing construction. 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 confirm that the geotechnical recommendations included in this report have been incorporated into the project plans. SITE CONDITIONS Surface The project area consists of a site located on the west side of Talbot Road, north of the intersection with 171st Street Southwest in Edmonds, Washington. The site is comprised of a single tax parcel, and was occupied by a single-family residence at the time of our field exploration. The existing site topography is gently sloped in nature, descending from east to west, with topographic relief on the order of 45 feet across the entirety of the site, with the majority of the sloping area located well outside of the project area within the eastern undeveloped portion of the site. A bluff overlooking the Puget Sound is present on the west side of the property, which descends some 65 feet towards the adjacent rail lines. Subsurface ESNW representatives observed, logged and sampled one hollow -stem boring and two hand - auger borings, associated with this report. The hollow -stem boring was advanced to a depth of 56.5 feet using a drill rig and operator contracted by the ESNW. Whereas the hand -auger borings was excavated using hand tools, and was advanced to a depth of four feet. The approximate location of the borings is depicted on the Boring Location Plan (Plate 2). Please refer to the soil logs provided in Appendix A for a more detailed description of the subsurface conditions. Topsoil Topsoil was encountered at the test locations on the order of three inches in thickness. Where topsoil is encountered during site grading activities, it is not suitable for use as structural fill nor should it be mixed with material to be used as structural fill. Topsoil or otherwise unsuitable material can be used in landscaping areas if desired. Fill Fill soil was not encountered at the test locations during our fieldwork. Fill soil may likely be encountered surrounding the existing buildings, roads, and utility alignments, and will have to be evaluated during construction for use as structural fill. Earth Solutions NW. LLC Mr. Robert Magrino and Ms. Bernadette D'Souza ES-8338 March 23, 2022 Page 3 Native Soil Underlying the topsoil at the test locations, native soils consisting of silty sand with gravel (Unified Soil Classification, SM), poorly graded sand (SP), poorly graded sand with silt (SP-SM), and sandy silt (ML) were encountered. The native soils were generally observed in a medium dense grading to very dense condition. These soil types were observed extending to the maximum exploration depth of 56.5 feet below existing grades. Geologic Setting The referenced geologic map resource identifies Whidbey Formation (Qw) pre -glaciation deposits. The referenced SCS soil survey describes Alderwood Everett gravelly sandy loam (4) 25 to 70 percent slope series soils for the site. This series of soil is typified by till plains. The majority of the native soil observed at the test locations are consistent with Whidbey Formation coarse sands depositional environments. Groundwater Groundwater seepage was not observed during the fieldwork (January 2022). Groundwater seepage should be expected within excavations at this site; particularly during the winter, spring, and early summer months. Groundwater 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 wetter, winter months. However, the groundwater table, nor seepage, was not observed on the subject site. ENVIRONMENTALLY CRITICAL AREA ASSESSMENT The existing site topography is steeply sloped in nature within the area to the west of the project area. Descending from east to west, a bluff is present with topographic relief on the order of 65 feet. The slope meets the criteria for a "steep slope" based on the City of Edmonds code. The slope descends from the lot elevation toward the Puget Sound. No signs of soil migration or instability have been observed during our site visits when reconnoitering the area at the top -of - slope. Additionally, the latest LiDAR imagery (available on the Washington State DNR LiDAR Portal) of the slopes was reviewed, and no signs of soil mobilization in the areas under concern were observed. The stability of the slope was analyzed as it relates to the proposed pool and deck. As part of our report preparation, we assessed the site for potential critical areas utilizing the City of Edmonds online GIS resources (critical areas maps). The subject site is described as possessing critical areas in the form of erosion and landslide. We have cited the City of Edmonds Critical Area Code (italics) and included a response to each item below: 1. The name and contact information of the applicant, a description of the proposal, and identification of the permit requested, - Robert Magrino & Bernadette D'Souza 11913 Marine View Drive Edmonds, WA 98026 Earth Solutions NW. LLC Mr. Robert Magrino and Ms. Bernadette D'Souza ES-8338 March 23, 2022 Page 4 2. A copy of the site plan for the development proposal including: a. A map to scale depicting critical areas, buffers, the development proposal, and any areas to be cleared; and b. A description of the proposed storm water management plan for the development and consideration of impacts to drainage alterations; c. The site plan shall identify the location of all native and nonnative vegetation of six inches dbh or larger; We have provided a site plan demonstrating the proposed buffer and setback from top -of - slope in addition to the current site layout. The client is responsible for providing further information as outlined in this code section. However, we recommend collecting all stormwater generated from proposed impervious surfaces and directing away from the sloped regions on and off -site. Failure to do so could result in an increased likelihood of landslide. 3. The dates, names, and qualifications of the persons preparing the report and documentation of any fieldwork performed on the site; The fieldwork was completed by Sam Suruda L.G. on January 17, 2022. The fieldwork consisted of observing and logging of two borings advanced to a maximum depth of 56.5 feet. The report was prepared by Stephen H. Avril (Project Manager), and was reviewed and stamped by Kyle R. Campbell P.E. (Principal Engineer). 4. Identification and characterization of all critical areas, wetlands, water bodies, shorelines, and buffers adjacent to the proposed project area; The critical areas being studied by ESNW in this case were limited to the steep slope located on the west side of the subject site which descends towards The Puget Sound, with elevation change on the order of 65 feet. 5. A description of reasonable efforts made to apply mitigation sequencing pursuant to ECDC 23.40.120, Mitigation sequencing, to avoid, minimize, and mitigate impacts to critical areas; There are no planned modifications for the subject slopes. As such we see no potential impacts to the critical areas based on our analysis. However, it should be considered to not allow for a net increase in both surface and subsurface water volumes on and in the sloped regions on the subject site. Earth Solutions NW. LLC Mr. Robert Magrino and Ms. Bernadette D'Souza March 23, 2022 ES-8338 Page 5 6. Report requirements specific to each critical area type as indicated in the corresponding chapters of this title; We have analyzed the slope stability for a pre- and post -construction condition. See summary of our analysis below. 7. A statement specifying the accuracy of the report and all assumptions made and relied upon; The strength parameters used for the current slope stability analyses are consistent with the soil conditions observed in the field. The search envelope encompasses the entire slope, top -of -slope area, and beyond the proposed pool and deck in order to provide a broad analysis. The results suggest a calculated critical slope factor of safety (FOS) which are demonstrated on the computer model (see attached) for static conditions and seismic conditions. The FOS are acceptable from a slope stability standpoint. The results of our stability analyses indicate the slope is stable in a static condition and exhibits an adequate FOS against rotational failure from a design seismic event. In our opinion, this report and assumptions utilized in our analysis can be relied upon. 8. A description of the methodologies used to conduct the critical areas study, including references; and The native soil conditions encountered at the boring locations on the site consist of medium dense transitioning to very dense silty sand with gravel (SM), poorly graded sand (SP), poorly graded sand with silt (SP-SM), and sandy silt (ML). We utilized Geostudio SlopeW computer software to model the bluff on the west of the subject site. Based on our modeling of the slopes the total setback for the deck can be reduced to 39 feet, and for the pool 68 feet (as is being proposed). Please see the attached SlopeW outputs for a detailed description of the results of our slope modeling, including the factors of safety for each condition. For projects such as the current proposal, professional judgement must be used particularly with respect to the complex nature of slope stability modeling to ensure the project is designed adequately and is also value engineered where practical. On this basis, in our opinion, the soil strength parameters used to model slope stability of this site were considered somewhere between fully drained and undrained. Therefore, including a value for cohesion is appropriate for modeling the existing soils on this site when considering a transient condition such as seismic shaking. Earth Solutions NW. LLC Mr. Robert Magrino and Ms. Bernadette D'Souza March 23, 2022 ES-8338 Page 6 The friction angles used for the current slope stability analyses are consistent with the N- values detailed in the boring log. We included some cohesion to the soil for the transitory seismic condition, which is consistent with current standard of practice for slope stability analyses. We focused the model search to rotational and translation failure geometries, because shallow `skin slide' debris flows are not expected to be the predominate failure mode for this site during a design seismic event. The search envelope encompasses nearly the entire slope and top of slope area (including the pool and deck), to provide a broad analysis. The results suggest a calculated critical slope factor of safety (FOS) over 1.5 for static conditions and 1.2 for seismic conditions, which are acceptable from a slope stability standpoint. The results of our stability analyses indicate the slope is stable in a static condition and exhibits an adequate FOS against rotational failure from a design seismic event. In reality the slope on this site could likely experience significantly larger deformation without compromising the stability of the overall slope or affecting life safety. The results of our analyses indicate the slope is stable in the current condition and will likely increase in a built condition due to improved protection from water (interflow and surface) intrusion, as this is the most critical component to slope stability on this site. 9. Plans for adequate mitigation, as needed to offset any critical areas impacts, in accordance with the mitigation plan requirements in ECDC 23.40.130. We do not foresee any necessity for mitigation, as there will be no modifications to the subject slope. In our opinion, the proposed pool and deck construction is suitable from a geotechnical standpoint. Means to guard against leaking pipes and the pool should be considered, as addition of subsurface water on the subject slopes can increase the likelihood of soil mobilization. Best Management Practices (BMP) during and after construction must be considered as to not allow a net increase in water volumes sheeting towards the subject slope. DISCUSSION AND RECOMMENDATIONS General In our opinion, construction of the proposed structures is feasible from a geotechnical standpoint. The proposed pool and deck can be supported on competent native soils or new structural fill. Native soil capable of supporting residential foundations will likely be encountered at a depth of approximately one foot (and below) existing grade in most areas. Slab -on -grade floors should be supported on competent native soil or structural fill. Where loose or unsuitable soil conditions are exposed at foundation subgrade elevations, compaction of the soils to the specifications of structural fill, or overexcavation and replacement with a suitable structural fill material will be necessary. Recommendations for foundation design, site preparation, drainage, and other pertinent geotechnical recommendations are provided in the following sections of this study. Earth Solutions NW. LLC Mr. Robert Magrino and Ms. Bernadette D'Souza ES-8338 March 23, 2022 Page 7 This study has been prepared for the exclusive use of Mr. Robert Magrino and Ms. Bernadette D'Souza 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 Site preparation activities will involve site clearing and stripping, and implementation of temporary erosion control measures. The primary geotechnical considerations associated with site preparation activities include erosion control installation, subgrade preparation, excavation for the pool, underground utility installations, and preparation of subgrade areas. Temporary construction entrances and drive lanes, consisting of at least six inches of quarry spalls (potentially placed over geotextile) can be considered in order to minimize off -site soil tracking and to provide a stable access entrance surface. Erosion control measures should consist of silt fencing placed along the down gradient side of the site. Soil stockpiles should be covered or otherwise protected to reduce soil erosion. Temporary sedimentation ponds or other approaches for controlling surface water runoff should be in place prior to beginning earthwork activities. Where encountered, topsoil and organic -rich soil is not suitable for foundation support, nor is it suitable for use as structural fill. Topsoil or organic -rich soil can be used in non-structural areas if desired. Over -stripping of the site, however, should be avoided. A representative of ESNW should observe the initial stripping operations, to provide recommendations for stripping depths based on the soil conditions exposed during stripping. Structural fill soils placed throughout foundation and slab areas should be placed over a firm base. Loose or otherwise unsuitable areas of native soil exposed at subgrade elevations should be compacted to structural fill requirements or overexcavated and replaced with a suitable structural fill material. Where structural fill soils are used to construct foundation subgrade areas, the soil should be compacted to the requirements of structural fill described in the following section. Foundation subgrade areas should be protected from disturbance, construction traffic, and excessive moisture. Where instability develops below structural fill areas, use of a woven geotextile below the structural fill areas may be required. A representative of ESNW should observe structural fill placement in foundation, slab, and pavement areas. Earth Solutions NW. LLC Mr. Robert Magrino and Ms. Bernadette D'Souza ES-8338 March 23, 2022 Page 8 In -situ Soils The soils encountered at the test sites have a moderate sensitivity to moisture and were generally in a moist condition at the time of the exploration (January 2022). In this respect, the in -situ soils may not be suitable for use as structural fill if the soil moisture content is more than about 3 percent above the optimum level at the time of construction. In general, soils encountered during the site excavations that are excessively over the optimum moisture content will require moisture conditioning prior to placement and compaction. Conversely, soils that are below the optimum moisture content will require moisture conditioning through the addition of water prior to use as structural fill. If the in -situ soils are determined to not be suitable for use as structural fill, then use of a suitable imported soil may be necessary. In our opinion, a contingency should be included in the project budget for exporting unsuitable soil and importing structural fill; or moisture conditioning recommendations can be provided upon request based on field observations during the construction phase of on -site work. Imported Soils 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 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 placed in loose lifts of 12 inches or less and compacted to a relative compaction of 95 percent, based on the laboratory maximum dry density as determined by the Modified Proctor Method (ASTM D- 1557). Additionally, more stringent compaction specifications may be required for utility trench backfill zones, depending on the responsible utility district or jurisdiction. Foundations Based on the results of our study, the proposed structures can be supported on conventional spread and continuous footings bearing on competent native soils or new structural fill. Based on the soil conditions encountered at the test sites, competent native soils suitable for support of the pool and deck should be encountered at depths of approximately one foot, and below. Where loose or unsuitable soil conditions are exposed at subgrade elevations, compaction of the soils to the specifications of structural fill, or overexcavation and replacement with structural fill, may be necessary. Earth Solutions NW. LLC Mr. Robert Magrino and Ms. Bernadette D'Souza ES-8338 March 23, 2022 Page 9 Provided foundations will be supported as described above, the following parameters can be used for design of new foundations: • Allowable soil bearing capacity 2,500 psf • Passive earth pressure • Coefficient of friction 300 pcf (equivalent fluid) A one-third increase in the allowable soil bearing capacity can be assumed for short-term wind and seismic loading conditions. The above passive pressure and friction values include a factor - of -safety of 1.5. With structural loading as expected, total settlement in the range of one inch and differential settlement of about one-half inch is anticipated. The majority of the settlements should occur during construction, as dead loads are applied. Seismic Design Considerations The 2018 International Building Code (2018 IBC) recognizes the most recent edition of the Minimum Design Loads for Buildings and Other Structures manual (ASCE 7-16) for seismic design, specifically with respect to earthquake loads. Based on the soil conditions encountered at the test pit locations, the parameters and values provided below are recommended for seismic design per the 2018 IBC. Parameter Value Site Class D* Mapped short period spectral response acceleration, Ss (g) 1.315 Mapped 1-second period spectral response acceleration, S1 (g) 0.467 Short period site coefficient, Fa 1.000 Long period site coefficient, Fv 1.853 Adjusted short period spectral response acceleration, SMs (g) 1.315 Adjusted 1-second period spectral response acceleration, SM1 (g) 0.865 Design short period spectral response acceleration, SIDS (g) 0.877 Design 1-second period spectral response acceleration, SD1 (g) 0.577 Assumes very dense soil conditions, encountered to a maximum depth of 56.5 feet bgs during the January 2022 field exploration, remain very dense to at least 100 feet bgs. Based on our experience with the project geologic setting (glacial till) across the Puget Sound region, soil conditions are likely consistent with this assumption. Further discussion between the project structural engineer, the project owner (or their representative), and ESNW may be prudent to determine the possible impacts to the structural design due to increased earthquake load requirements under the 2018 IBC. ESNW can provide additional consulting services to aid with design efforts, including supplementary geotechnical and geophysical investigation, upon request. Earth Solutions NW. LLC Mr. Robert Magrino and Ms. Bernadette D'Souza ES-8338 March 23, 2022 Page 10 Liquefaction is a phenomenon where saturated or loose soil suddenly loses internal strength and behaves as a fluid. This behavior is in response to increased pore water pressures resulting from an earthquake or another intense ground shaking. In our opinion, site susceptibility to liquefaction may be considered negligible. The absence of a shallow groundwater table and the dense characteristics of the native soil were the primary bases for this opinion. Slab -On -Grade Floors Slab -on -grade floors for the proposed structuress constructed at this site should be supported on a firm and unyielding subgrade. Where feasible, the soil exposed at the slab -on -grade subgrade level can be compacted in place to the specifications of structural fill. Unstable or yielding areas of the subgrade should be recompacted or overexcavated and replaced with suitable structural fill prior to construction of the slab. 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 (percent passing the #200 sieve, based on the minus three-quarter inch fraction). In areas where slab moisture is undesirable, installation of a vapor barrier below the slab should be considered. If a vapor barrier is to be utilized it should be a material specifically designed for use 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 can be used for retaining wall design: • Active earth pressure (yielding condition) • At -rest earth pressure (restrained condition) • Traffic surcharge for passenger vehicles (where applicable) • Passive earth pressure • Coefficient of friction • Seismic surcharge (active condition) 35 pcf (equivalent fluid) 55 pcf 70 psf (rectangular distribution) 300 pcf (equivalent fluid) NMI 8H (where H equals retained height) 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. Earth Solutions NW. LLC Mr. Robert Magrino and Ms. Bernadette D'Souza ES-8338 March 23, 2022 Page 11 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 approved discharge location. A typical retaining wall drainage detail is provided on Plate 3. Drainage Seepage may be encountered in excavations on the site, particularly during winter, spring, and early summer months. Temporary measures to control surface water runoff and groundwater during construction would likely involve interceptor trenches and sumps. ESNW should be consulted during preliminary grading to identify areas of seepage and to provide recommendations to reduce the potential for instability related to seepage effects. Finish grades must slope away from the structures at an inclination of at least 2 percent for a distance of at ten feet or as adjacent building setbacks allow. In addition, surface water should be controlled utilizing best management practices (BMP) during, and after, construction on the subject site. We recommend not allowing for a net increase in surface, and subsurface, water volumes. Failure to control the amount of water sheeting or infiltrating towards the slopes could result in an increased risk of landslide. Subsurface drainage measures such as interceptor trenches (aka French Drains) should be considered to intercept any surface or subsurface water before is allowed to reach the top -of -slope region on the west side of the site. This may include installation of French Drains on the west side of the pool in the happenstance of a leak. The drains should be tied -into an approved discharge point, and not allowed to daylight to where the water reaches the sloped regions. Footing drains should be installed given the nature of the soils on the site. A typical foundation drain detail is provided as Plate 4. Excavations and Slopes The Federal Occupation Safety and Health Administration (OSHA) and the Washington Industrial Safety and Health Act (WISHA) provide soil classification in terms of temporary slope inclinations. Based on the soil conditions encountered at the test locations, existing fill, loose native soil and any soil where groundwater seepage is exposed, are classified as Type C by OSHA/WISHA. Temporary slopes over four feet in height in Type C soils must be sloped no steeper than 1.5H:1 V (Horizontal:Vertical). The presence of perched groundwater may cause caving of the temporary slopes due to hydrostatic pressure. The native glacially consolidated soils observed on the subject site are classified as Type B. Temporary slopes over four feet in height in Type B soils must be sloped no steeper than 1 H:1 V. Temporary excavations with inclinations steeper than those described may be acceptable from a geotechnical standpoint. ESNW should be consulted during the design phase to provide recommendations for steeper temporary excavations if necessary. ESNW should observe site excavations to confirm the soil type and allowable slope inclination. If the recommended temporary slope inclination cannot be achieved, temporary shoring may be necessary to support excavations. Earth Solutions NW. LLC Mr. Robert Magrino and Ms. Bernadette D'Souza ES-8338 March 23, 2022 Page 12 Permanent slopes should maintain a gradient of 2H:1V, or flatter, and should be planted with vegetation to enhance stability and to minimize erosion. Permanent grading should take into account our recommendation of disallowing for a net increase in the surface water volumes which may sheet towards the sloped regions. A representative of ESNW should observe temporary and permanent slopes to confirm the slope inclinations, and to provide additional excavation and slope recommendations, as necessary. Utility Support and Trench Backfill In our opinion, the soils anticipated to be exposed in utility excavations should generally be suitable for support of utilities. Organic or highly compressible soils encountered in the trench excavations should not be used for supporting utilities. The on -site soil may not be suitable for use as trench backfill if the soil moisture content is too high at the time of compaction. Utility trench backfill should be placed and compacted to the specifications of structural fill provided in this report, or to the applicable City of Edmonds specifications. 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 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. Earth Solutions NW. 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ESNW cannot be responsible for any subsequent misinterpretation of the information resulting from black & white reproductions of this plate. ^ `F C :4n Q��a 9 �loo�� 6 III r n 1l / -� � 188tee hst tsouthwee t- _ -- Penny Lane 189th Place Southiys 189th Place Southwest 190th Street Southwest �E 191st Street Southwest"We IN WA 99 t 92nd Place South P 792nd P\ace Southwest st m Park Way Vicinity Map Magrino-D'Souza SFR Edmonds, Washington Drwn. CAM I Date 02/21/20221 Proj. No. 8338 Checked SES Date Feb.2022 Plate 1 Puget * *� Sound �• ** * A' * * $� * s*+*Top of Bluff ---- s*\ 4't'4'A * � oaf 'o* aN + Q-o a i 25' Rear Yar / 50' Setback Setback', From ,ba, -k Propos LEGEND B-1 Approximate Location of — • — ESNW Boring, Proj. No. ES-8338, Jan. 2022 HA-1 Approximate Location of — • — ESNW Hand Auger Borin Proj. No. ES-8338, Jan. 2 Subject Site Existing Building Cross -Section 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. 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. —r-------- ------------i—------ i EXistin Drivewa , � � I I HA-1 � I HA-2 — • — Y I ad Pool I �--� e I I I \ ' I NORTH 022 NOT - TO - SCALE Y — Earth Solutions I VW NW LLC Enjneering, Construction Observation/Testing and E Subsurface Exploration Plan Magrino-D'Souza SFR Edmonds, Washington Drwn. MRS Date 03/22/2022 Proj. No. 8338 Checked SES Date Mar.2022 Plate 2 18" Min. o 0 o 0 o o° o 0 0� ��0 o ooc ° C 0 00 o o°o 0 00° °� oo . 0`0� o° 00 o o o o 0 0 0�0oo o 0 0 0 0 6 a ° o 0 0 0 0 0� 0 �o % Oo0oo 00 -0 �0 ° 00 00 o oo o 0 0. -o o o° o 000 0 °000 o °o o° o 0 0 o�000° o�� 00 Ooo o o g 8 0 oo o o o 0 000 o o o o0 po O o o° o0 o 0o 0 0 0 o o o o o0o' 0o °S 0 0 0 00 0 o 0 8 0o o0 8 o 0 °�o0 o 0 o o0 o 0 . 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: p°o O 0 o00 00 Free -draining Structural Backfill f •r•1•f• :rtir:r:rti 1-inch Drain Rock Structural Fill Perforated Rigid Drain Pipe (Surround in Drain Rock) SCHEMATIC ONLY - NOT TO SCALE NOT A CONSTRUCTION DRAWING Retaining Wall Drainage Detail Magrino-D'Souza SFR Edmonds, Washington Drwn. MRS Date 03/22/2022 Proj. No. 8338 Checked SHA Date Mar.2022 1 Plate 3 Perforated Rigid Drain Pipe (Surround in Drain Rock) 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 Footing Drain Detail Magrino-D'Souza SFR Edmonds, Washington Drwn. MRS Date 03/22/2022 Proj. No. 8338 Checked SHA Date Mar.2022 1 Plate 4 Appendix A Subsurface Exploration Boring Logs ES-8338 The subsurface conditions at the site were explored by excavating a total of two hand -auger borings and one hollow -stem auger boring across accessible portions of the property. The subsurface explorations were completed in January of 2022. The approximate test locations are illustrated on Plate 2 of this report. Logs of the borings are provided in this Appendix. The borings were excavated to a maximum depth of 56.5 feet below existing grades. Earth Solutions NW. LLC Earth Solutions NWLLC SOIL CLASSIFICATION CHART MAJOR DIVISIONS SYMBOLS TYPICAL DESCRIPTIONS GRAPH LETTER GRAVEL AND CLEAN GRAVELS ''� I.�•� � � � A. GW WELL -GRADED GRAVELS, GRAVEL - SAND MIXTURES, LITTLE OR NO FINES GRAVELLY SOILS (LITTLE OR NO FINES) ° �° o �° o pOo p Q Q oQ GP POORLY -GRADED GRAVELS, GRAVEL - SAND MIXTURES, LITTLE OR NO FINES COARSE GRAINED SOILS MORE THAN 50% OF COARSE GRAVELS WITH FINES o Q 0 °° o ' p GM SILTY GRAVELS, GRAVEL - SAND - SILT MIXTURES FRACTION RETAINED ON NO. 4 SIEVE (APPRECIABLE AMOUNT OF FINES) �±� V CLAYEY GRAVELS, GRAVEL - SAND - CLAY MIXTURES SAND AND CLEAN SANDS SW WELL -GRADED SANDS, GRAVELLY SANDS, LITTLE OR NO FINES MORE THAN 50% OF MATERIAL IS LARGER THAN SANDY NO. 200 SIEVE SIZE SOILS (LITTLE OR NO FINES) ::. SP POORLY -GRADED SANDS, GRAVELLY SAND, LITTLE OR NO FINES SANDS WITH FINES c•M c SILTY SANDS, SAND - SILT MIXTURES MORE THAN 50% OF COARSE FRACTION PASSING ON NO. 4 SIEVE (APPRECIABLE AMOUNT OF FINES) cC �7 CLAYEY SANDS, SAND - CLAY MIXTURES INORGANIC SILTS AND VERY FINE ML SANDS, ROCK FLOUR, SILTY OR CLAYEY FINE SANDS OR CLAYEY SILTS WITH SLIGHT PLASTICITY FINE GRAINED SOILS SILTS AND LIQUID LIMIT LESS THAN 50 CLAYS CL INORGANIC CLAYS OF LOW TO MEDIUM PLASTICITY, GRAVELLY CLAYS, SANDY CLAYS, SILTY CLAYS, LEAN CLAYS OL ORGANIC SILTS AND ORGANIC SILTY CLAYS OF LOW PLASTICITY MORE THAN 50% OF MATERIAL IS SMALLER THAN NO. 200 SIEVE MH INORGANIC SILTS, MICACEOUS OR DIATOMACEOUS FINE SAND OR SILTY SOILS SIZE SILTS AND LIQUID LIMIT CLAYS GREATER THAN 50 CI I INORGANIC CLAYS OF HIGH PLASTICITY OH ORGANIC CLAYS OF MEDIUM TO HIGH PLASTICITY, ORGANIC SILTS HIGHLY ORGANIC SOILS '/ ` 1/ 01/ 01/ N \„ \„ „ 0 0„ PT PEAT, HUMUS, SWAMP SOILS WITH HIGH ORGANIC CONTENTS 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. LU >J a x m z 0 y Earth Solutions NW, LLC BORING NUMBER B-1 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 PAGE 1 OF 3 Telephone: 425-449-4704 Fax: 425-449-4711 PROJECT NUMBER ES-8338 PROJECT NAME Magrino-D'Souza SFR DATE STARTED 1/17/22 COMPLETED 1/17/22 GROUND ELEVATION DRILLING CONTRACTOR Geologic Drill Partners LATITUDE 47.84569 LONGITUDE-122.34022 DRILLING METHOD HSA GROUND WATER LEVEL: LOGGED BY SES CHECKED BY SHA SZ AT TIME OF DRILLING NOTES Surface Conditions: landscaping area L o }� w COW � Uj U a Lm g > 0z J D Q TESTS a0 O MATERIAL DESCRIPTION Lv O CO❑ > j �� 2z U zLu 0 Brown silty SAND with gravel, medium dense, wet SM [USDA Classification: gravelly loamy SAND] SS 22 5-5-6 MC = 33.1 % (11) Fines =20.1% % 4.5 SP Dark brown poorly graded SAND, medium dense, moist to wet 5 SS 67 6($)3 MC = 15.3% 7.0 Gray sandy SILT, dense to very dense, moist SS 22 12-15-29 MC = 19.4% 10 [USDA Classification: slightly gravelly LOAM] SS 67 12-18-20 MC = 23.1 % ML (38) Fines = 79.9% 14.0 Brown poorly graded SAND with silt, very dense, damp 15 [USDA Classification: slightly gravelly SAND] SS 89 17-18-23 MC = 9.6% (41) Fines = 6.7% SP- SM 20 20.0 (Continued Next Page) y Earth Solutions NW, LLC BORING NUMBER B-1 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 PAGE 2 OF 3 Telephone: 425-449-4704 Fax: 425-449-4711 PROJECT NUMBER ES-8338 PROJECT NAME Magrino-D'Souza SFR DATE STARTED 1/17/22 COMPLETED 1/17/22 GROUND ELEVATION DRILLING CONTRACTOR Geologic Drill Partners LATITUDE 47.84569 LONGITUDE-122.34022 DRILLING METHOD HSA GROUND WATER LEVEL: LOGGED BY SES CHECKED BY SHA SZ AT TIME OF DRILLING NOTES Surface Conditions: landscaping area L o }� w COW � Uj U a Lm g > 0z J D Q TESTS a0 O MATERIAL DESCRIPTION Lv ❑ O COmOzLu j �� 2z U 20 Brown poorly graded SAND with silt, very dense, damp SS 89 20-28-30 MC = 4.7% (58) 25 SS 100 17-24-27 MC = 9.8% 30 SP- SM SS 100 18(49)26 MC = 10.6% 35 -becomes gray, moist SS 100 21-27-33 MC = 14.2% (60) 40 (Continued Next Page) J W a x m J W Z W y Earth Solutions NW, LLC BORING NUMBER B-1 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 PAGE 3 OF 3 Telephone: 425-449-4704 Fax: 425-449-4711 PROJECT NUMBER ES-8338 PROJECT NAME Magrino-D'Souza SFR DATE STARTED 1/17/22 COMPLETED 1/17/22 GROUND ELEVATION DRILLING CONTRACTOR Geologic Drill Partners LATITUDE 47.84569 LONGITUDE-122.34022 DRILLING METHOD HSA GROUND WATER LEVEL: LOGGED BY SES CHECKED BY SHA SZ AT TIME OF DRILLING NOTES Surface Conditions: landscaping area w o >_ (n W Uj U a wm g w > 0z� J D Q TESTS a0 O MATERIAL DESCRIPTION w" ❑ O COmOZLu j �� 2Z U 40 Brown poorly graded SAND with silt, very dense, damp (continued) SS 100 29-266-36 MC = 6.6% SP- SM 42.9 Gray poorly graded SAND with silt, very dense, moist 45 0.5" ML lens SS 100 22(77�45 MC = 13.3% SP- " 50 SM -becomes damp SS 100 24-50/6" MC = 6.2% 55 -increasing grain size SS 100 23(71�40 MC = 4.5% 56.5 Boring terminated at 56.5 feet below existing grade. No groundwater encountered during drilling. Boring backfilled with bentonite. y Earth Solutions NW, LLC BORING NUMBER HA-1 15365 N.E. 90th Street, Suite 100 PAGE 1 OF 1 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 PROJECT NUMBER ES-8338 PROJECT NAME Magrino-D'Souza SFR DATE STARTED 1/17/22 COMPLETED 1/17/22 GROUND ELEVATION DRILLING CONTRACTOR ESNW Rep LATITUDE LONGITUDE DRILLING METHOD GROUND WATER LEVEL: LOGGED BY SES CHECKED BY SHA SZ AT TIME OF DRILLING NOTES Depth of Topsoil & Sod 3": grass L = }� H L U 2 w g TESTS Q O MATERIAL DESCRIPTION ❑ 2 Z U Q U 0 Brown silty SAND with gravel, loose to medium dense, damp SM -becomes medium dense MC=5.1% 4.0 Hand auger boring terminated at 4.0 feet below existing grade. No groundwater encountered during excavation. No caving observed. v Earth Solutions NW, LLC 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 BORING NUMBER HA-2 PAGE 1 OF 1 PROJECT NUMBER ES-8338 PROJECT NAME Magrino-D'Souza SFR DATE STARTED 1/17/22 COMPLETED 1/17/22 GROUND ELEVATION DRILLING CONTRACTOR ESNW Rep LATITUDE LONGITUDE DRILLING METHOD GROUND WATER LEVEL: LOGGED BY SES CHECKED BY SHA SZ AT TIME OF DRILLING NOTES Depth of Topsoil & Sod 3": grass L }� U = w H L _j g TESTS 2 O UUi Q QZ U MC = 16. MATERIAL DESCRIPTION Brown silty SAND with gravel, loose to medium dense, moist -becomes medium dense Hand auger boring terminated at 3.5 feet below existing grade. No groundwater encountered during excavation. No caving observed. Appendix B Laboratory Test Results ES-8338 Earth Solutions NW. LLC Earth Solutions NW, LLC 15365 N.E. 90th Street, Suite 100 Redmond, Washington 98052 Telephone: 425-449-4704 Fax: 425-449-4711 GRAIN SIZE DISTRIBUTION PROJECT NUMBER ES-8338 PROJECT NAME Magrino-D'Souza SFR U.S. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS I HYDROMETER 100 95 90 85 80 75 70 65 x w 60 m 55 w 50 z LL 45 z w rr 40 w a 35 30 25 20 15 10 5 0 3 4 b b l U "14 l b ZU 3U 4U bU bU l UU 14U ZUU 100 10 1 0.1 0.01 0.001 GRAIN SIZE IN MILLIMETERS COBBLES GRAVEL SAND SILT OR CLAY coarse fine coarse medium fine Specimen Identification Classification Cc CU • B-01 2.50ft. USDA: Brown Gravelly Loamy Sand. USCS: SM. m B-01 10.00% USDA: Gray Slightly Gravelly Loam. USCS: ML with Sand. A B-01 15.00ft. USDA: Brown Slightly Gravelly Sand. USCS: SP-SM. 1.46 3.72 Specimen Identification D100 D60 D30 D10 LL PL PI %Silt %Clay 0 B-01 2.5ft. 19 0.651 0.186 20.1 m B-01 10.0ft. 19 79.9 A B-01 15.0ft. 9.5 0.468 0.294 0.126 6.7 Appendix C SlopeW Output ES-8338 Earth Solutions NW. LLC 90 e0 70 50 50 40 30 0 O 7 20 O1 W -1( -2( -y -4( -56 -110 Poo[ Deck Surchage 963 -00 -70 -50 -30 -10 10 30 50 70 90 110 140 150 170 190 210 230 Distance D'Souza Deck and Pool Report generated using GeoStudio 2019. Copyright O 1991-2018 GEOSLOPE International Ltd. File Information File Version: 10.00 Created By: Steve Avril Last Edited By: Steve Avril Revision Number: 19 Date: 03/21/2022 Time: 11:35:18 AM Tool Version: 10.0.0.17401 File Name: ES 8338 A -A' Proposed Static.gsz Directory: C:\Users\steve.avril\Documents\ Last Solved Date: 03/21/2022 Last Solved Time: 11:3S:47 AM Project Settings Unit System: U.S. Customary Units Analysis Settings D'Souza Deck and Pool Description: A -A' Kind: SLOPE/W Method: Morgenstern -Price Settings Side Function Interslice force function option: Half -Sine PWP Conditions from: (none) Unit Weight of Water: 62.430189 pcf Slip Surface Direction of movement: Left to Right Use Passive Mode: No Slip Surface Option: Entry and Exit Critical slip surfaces saved: 1 Optimize Critical Slip Surface Location: No Tension Crack Option: (none) Distribution F of S Calculation Option: Constant Advanced Geometry Settings Minimum Slip Surface Depth: 0.1 ft Number of Slices: 30 Factor of Safety Convergence Settings Maximum Number of Iterations: 100 Tolerable difference in F of S: 0.001 Solution Settings Search Method: Root Finder Tolerable difference between starting and converged F of S: 3 Maximum iterations to calculate converged lambda: 20 Max Absolute Lambda: 2 Materials Medium Dense SM Model: Mohr -Coulomb Unit Weight: 125 pcf Cohesion': 0 psf Phi': 34 ° Phi-B: 0 ° Loose SP Model: Mohr -Coulomb Unit Weight: 125 pcf Cohesion': 0 psf Phi': 32 ° Phi-B: 0 ° Hard ML Model: Mohr -Coulomb Unit Weight: 125 pcf Cohesion': 600 psf Phi': 34 ° Phi-B: 0 ° Very Dense SP Model: Mohr -Coulomb Unit Weight: 125 pcf Cohesion': 600 psf Phi': 36 ° Phi-B: 0 ° Water Model: Mohr -Coulomb Unit Weight: 62 pcf Cohesion': 0 psf Phi': 0 ° Phi-B: 0 ° Slip Surface Entry and Exit Left Type: Range Left -Zone Left Coordinate: (-106, 76.636364) ft Left -Zone Right Coordinate: (36.875, 40) ft Left -Zone Increment: 20 Right Type: Range Right -Zone Left Coordinate: (53.375, 28) ft Right -Zone Right Coordinate: (199, 0) ft Right -Zone Increment: 20 Radius Increments: 20 Slip Surface Limits Left Coordinate: (-110, 77) ft Right Coordinate: (210, -46) ft Surcharge Loads Surcharge Load 1 Surcharge (Unit Weight): 100 pcf Direction: Vertical Coordinates x Y -69 ft 78 ft -39 ft 178 ft Points x v Point 1 -110 ft 77 ft Point 2 0 ft 67 ft Point 3 4 ft 64 ft Point 4 -110 ft 64 ft Point 5 loft 60 ft Point 6 -110 ft 60 ft Point 7 19 ft 53 ft Point 8 -110 ft 53 ft Point 9 85 ft 5 ft Point 10 135 ft 5 ft Point 11 144 ft 0 ft Point 12 209 ft 0 ft Point 13 210 ft -46 ft Point 14 -110 ft -46 ft Point 15 -69 ft 73.272727 ft Point 16 -69 ft 69 ft Point 17 -89 ft 69 ft Point 18 -89 It 75.090909 ft Regions Material Points Area Region 1 Medium Dense SM 1,4,3,2,15,16,17,18 782.36 ft2 Region 2 Loose SP 3,5,6,4 468 ft2 Region 3 Hard ML 5,7,8,6 871.5 ft2 Region 4 Very Dense SP 7,9,10,11,12,13,14,8 23,720 ft2 Region S Water 15,18,17,16 103.64 ft2 Slip Results Slip Surfaces Analysed: 8385 of 9261 converged Current Slip Surface Slip Surface: 4,522 Factor of Safety: 1.963 Volume: 1,902.1675 ft' Weight: 237,770.93 Ibf Resisting Moment: 41,228,559 Ibf•ft Activating Moment: 20,994,762 Ibf•ft Resisting Force: 196,963.11 Ibf Activating Force: 100,330.62 Ibf Slip Rank: 51 of 9,261 slip surfaces Exit: (84.592184, 5.2965934) ft Entry: (-30.236248, 69.74875) ft Radius: 181.8829 ft Center: (110.16488, 185.37276) ft Slip Slices X y PWP I Base Normal Stress Frictional Strength Cohesive Strength Suctic Slice 1 -27.766947 ft 66.874375 ft 0 psf 225.40248 psf 152.03589 psf 0 psf 0 psf Slice 2 -23.450764 ft 62 ft 0 psf 600.93535 psf 375.50608 psf 0 psf 0 psf Slice 3 -19.845613 ft 58.20226 ft 0 psf 692.5232 psf 467.11279 psf 600 psf 0 psf Slice 4 -16,328673 ft 54.70226 ft 0 psf 972.91293 psf 656.23806 psf 600 psf 0 psf Slice 5 -12.748928 ft 51.329938 ft 0 psf 1,225.9026 psf 890.67035 psf 600 psf 0 psf Slice 6 -9.1063769 ft 48.077693 ft 0 psf 1,483.9865 psf 1,078.1793 psf 600 psf 0 psf Slice 7 -5.4638262 ft 44.995329 ft 0 psf 1,733.7177 psf 1,259.6196 psf 600 psf 0 psf Slice 8 -1.8212754 ft 42.071864 ft 0 psf 1,979.0282 psf 1,437.8482 psf 600 psf 0 psf Slice 9 2 ft 39.168937 ft 0 psf 2,122.1276 psf 1,541.816 psf 600 psf 0 psf Slice 10 5.5 ft 36.63377 ft 0 psf 2,168.7437 psf 1,575.6845 psf 600 psf 0 psf Slice 11 8.5 ft 34.56703 ft 0 psf 2,219.033 psf j 1,612.2219 psf 600 psf 0 psf Slice 12 12.25 ft 32.11828 ft 0 psf 2,256.1967 psf 1,639.2229 psf 600 psf 0 psf Slice 13 16.75 ft 29.333753 ft 0 psf 2,277.8388 psf 1,654.9467 psf 600 psf 0 psf Slice 14 20.929182 ft 26.900438 ft 0 psf 2,298.9557 psf 1,670.2891 psf 600 psf 0 psf Slice 15 24.787546 ft 24.788435 ft 0 psf 2,318.6305 psf 1,684.5837 psf 600 psf 0 psf Slice 16 28.645909 ft 22.795429 ft 0 psf 2,327.0922 psf 1,690.7315 psf 600 psf 0 psf Slice 17 32.504273 ft 20.917091 ft 0 psf 2,321.557 psf 1,686.7099 psf 600 psf 0 psf Slice 18 36.362637 ft 19.149531 ft 0 psf 2,299.0253 psf 1,670.3397 psf 600 psf 0 psf Slice 19 40.221001 ft 17.489245 ft 0 psf 2,256.422 psf 1,639.3866 psf 600 psf 0 psf Slice 20 44.079365 ft 15.93308 ft 0 psf 2,190.7787 psf 1,591.6939 psf 600 psf 0 psf Slice 21 47.937728 ft 14.478188 ft 0 psf 2,099.4546 psf 1,525.343 psf 600 psf 0 psf Slice 22 51.796092 ft 13.122001 ft 0 psf 1,980.3811 psf 1,438.8311 psf 600 psf 0 psf Slice 23 155.654456 ft 11.862204 ft 0 psf 1,832.3059 psf 1,331.2481 psf 600 psf 0 psf Slice 24 59.51282 ft 10.69671 ft 0 psf 1,655.0044 psf 1,202.4311 psf 600 psf 0 psf Slice 25 63.371183 ft 9.6236408 ft 0 psf 1,449.4241 psf 1,053.0682 psf 600 psf 0 psf Slice 26 67.229547 ft 8.6413131 ft 0 psf 1,217.7265 psf 884.73009 psf 600 psf 0 psf Slice 27 71.087911 ft 7.7482202 ft 0 psf 963.207 psf 699.81085 psf 600 psf 0 psf Slice 28 74.946275 ft 6.9430213 ft 0 psf 690.08782 psf 501.37815 psf 600 psf 0 psf Slice 29 78.804638 ft 6.2245308 ft 0 psf 403.20235 psf 292.94365 psf J 600 psf 0 psf Slice 30 1 82.663002 ft 1 5.5917086 ft 1 0 psf 1 107.60838 psf J 78.182067 psf 1 600 psf J 0 psf 90 30 70 50 50 40 30 C O j 20 0) W -o -110 Pool Deck Surchage ES 8338 Proposed 1 223 -90 -70 -50 -30 10 10 30 50 70 90 110 130 150 170 100 210 230 Distance D'Souza Deck and Pool Report generated using GeoStudio 2019. Copyright © 1991-2018 GEOSLOPE International Ltd. File Information File Version: 10.00 Created By: Steve Avril Last Edited By: Steve Avril Revision Number: 18 Date:03/21/2022 Time: 11:25:44 AM Tool Version: 10.0.0.17401 File Name: ES 8338 A -A' Proposed Seismic.gsz Directory: C:\Users\steve.avril\Documents\ Last Solved Date: 03/21/2022 Last Solved Time: 11:31:41 AM Project Settings Unit System: U.S. Customary Units Analysis Settings D'Souza Deck and Pool Description: A -A' Kind: SLOPE/W Method: Morgenstern -Price Settings Side Function Interslice force function option: Half -Sine PWP Conditions from: (none) Unit Weight of Water: 62.430189 pcf Slip Surface Direction of movement: Left to Right Use Passive Mode: No Slip Surface Option: Entry and Exit Critical slip surfaces saved: 1 Optimize Critical Slip Surface Location: No Tension Crack Option: (none) Distribution F of S Calculation Option: Constant Advanced Geometry Settings Minimum Slip Surface Depth: 0.1 ft Number of Slices: 30 Factor of Safety Convergence Settings Maximum Number of Iterations: 100 Tolerable difference in F of S: 0.001 Solution Settings Search Method: Root Finder Tolerable difference between starting and converged F of S: 3 Maximum iterations to calculate converged lambda: 20 Max Absolute Lambda: 2 Materials Medium Dense SM Model: Mohr -Coulomb Unit Weight: 125 pcf Cohesion': 0 psf Phi': 34 ° Phi-B: 0 ° Loose SP Model: Mohr -Coulomb Unit Weight: 125 pcf Cohesion': 0 psf Phi': 32 ° Phi-B: 0 ° Hard ML Model: Mohr -Coulomb Unit Weight: 125 pcf Cohesion': 600 psf Phi': 34 ° Phi-B: 0 ° Very Dense SP Model: Mohr -Coulomb Unit Weight: 125 pcf Cohesion': 600 psf Phi': 36 ° Phi-B: 0 ° Water Model: Mohr -Coulomb Unit Weight: 62 pcf Cohesion': 0 psf Phi': 0' Phi-B: 0 ° Slip Surface Entry and Exit Left Type: Range Left -Zone Left Coordinate: (-106, 76.636364) ft Left -Zone Right Coordinate: (36.875, 40) ft Left -Zone Increment: 20 Right Type: Range Right -Zone Left Coordinate: (53.375, 28) ft Right -Zone Right Coordinate: (199, 0) ft Right -Zone Increment: 20 Radius Increments: 20 Slip Surface limits Left Coordinate: (-110, 77) ft Right Coordinate: (210, -46) ft Seismic Coefficients Horz Seismic Coef.: 0.28 Surcharge Loads Surcharge load 1 Surcharge (Unit Weight): 100 pcf Direction: Vertical Coordinates 4Y X 69 ft 78 ft -39 ft 178 ft Points Point 1 X Y -110 ft 77 ft Point 2 0 ft 67 ft Point 3 4 ft 64 ft Point 4 -110 ft 64 ft Point 5 loft 60 ft Point 6 -110 ft 60 ft Point 7 19 ft 53 ft Point 8 -110 ft 53 ft Point 9 85 ft 5 ft Point 10 135 It 5 ft Point 11 144 ft 0 ft Point 12 209 It j 0 ft Point 13 210 ft -46 ft Point 14 -110 ft -46 ft Point 15 -69 ft 73.272727 ft Point 16 -69 ft 69 ft Point 17 -89 ft 69 ft Point 18 -89 ft 75.090909 ft Regions Material Points Area Region 1 Medium Dense SM 1,4,3,2,15,16,17,18 782.36 ftZ Region 2 Loose SP 3,5,6,4 468 ftZ Region 3 Hard ML 15,7,8,6 871.5 ftZ I Region 4 Very Dense SP 7,9,10,11,12,13,14,8 23,720 ftZ Region 5 Water 15,18,17,16 103.64 ftz Slip Results Slip Surfaces Analysed: 8396 of 9261 converged Current Slip Surface Slip Surface: 4,522 Factor of Safety: 1.223 Volume: 1,902.1675 ft3 Weight: 237,770.93 Ibf Resisting Moment: 37,570,063 Ibf•ft Activating Moment: 30,720,847 Ibf•ft Resisting Force: 181,541.05 Ibf Activating Force: 148,372.09 Ibf Slip Rank: 1 of 9,261 slip surfaces Exit: (84.592184, 5.2965934) ft Entry: (-30.236248, 69.74875) ft Radius: 181.8829 ft Center: (110.16488, 185.37276) ft Slip Slices X y PWP Base Normal Stress Frictional Strength Cohesive Strength Suctio Slice 1 -27.766847 ft 66.874375 ft 0 psf 182.39009 psf 123.02367 psf 0 psf 0 psf Slice 2 -23.450764 ft 62 ft 0 psf 464.26031 psf 290.10204 psf 0 psf 0 psf Slice 3 -19.845613 ft 58.20226 ft 0 psf 448.2193 psf 1302.32773 psf 600 psf 0 psf Slice 4 -16.328673 ft 54.70226 ft 0 psf 667.33765 psf 450.12493 psf 600 psf 0 psf Slice 5 -12.748928 ft 51.329938 ft 0 psf 853.75725 psf 620.29095 psf 600 psf 0 psf Slice 6 -9.1063769 ft 48.077693 ft 0 psf 1,033.7874 psf 751.09049 psf 600 psf 0 psf Slice 7 -5.4638262 ft 44.995329 ft 0 psf 1,201.2236 psf 872.74006 psf 600 psf 0 psf Slice 8 -1.8212754 ft 42.071864 ft 0 psf 1,362.7837 psf 990.12029 psf 600 psf 0 psf Slice 9 2 ft 39.168937 ft 0 psf 1,455.2049 psf 1,057.2683 psf 600 psf 0 psf Slice 10 5.5 ft 36.63377 ft 0 psf 1,489.7571 psf 1,082.3719 psf 600 psf 0 psf Slice 11 8.5 ft 34.56703 ft 0 psf 11,535.7326 psf 1,115.7751 psf 600 psf 0 psf Slice 12 12.25 ft 32.11828 ft 0 psf 1,589.1079 psf 1,154.5545 psf 600 psf 0 psf Slice 13 16.75 ft 29.333753 ft 0 psf 1,657.8949 psf 1,204.5239 psf 600 psf 0 psf Slice 14 20.929182 ft 26.900438 ft 0 psf 1,743.1753 psf 1,266.491 psf 600 psf 0 psf Slice 15 24.787546 ft 24.789435 ft 0 psf 1,839.2052 psf 1,336.2608 psf 600 psf 0 psf Slice 16 28.645909 ft 22.795429 ft 0 psf 1,941.4977 psf 1,410.5807 psf 600 psf 0 psf Slice 17 32.504273 ft 20.917091 ft 0 psf 2,044.1259 psf 1,485.1444 psf 600 psf 0 psf Slice 18 36.362637 ft 19,149531 ft 0 psf 2,139.0974 psf 1,SS4.1452 psf 600 pst 0 psf Slice 19 40.221001 ft 17.489245 ft 0 psf 2,216.5436 psf 1,610.4132 psf 600 psf 0 psf Slice 20 44.079365 ft 15.93308 ft 0 psf 2,265.3131 psf 1,645.8463 psf 600 psf 0 psf Slice 21 47.937728 ft 14.478188 ft 0 psf 2,274.0212 psf 1,652.1731 psf 600 psf 0 psf Slice 22 51.796092 ft 13.122001 ft 0 psf 2,232.4888 psf 1,621.998 psf 600 psf 0 psf Slice 23 55.654456 ft 11.862204 ft 0 psf 2,133.3413 psf 1,549.9632 psf 600 psf 0 psf Slice 24 59.51282 ft 10.69671 ft 0 psf 1,973.4125 psf 1,433.7681 psf 600 psf 0 psf Slice 25 63.371183 ft 9.6236408 ft 0 psf 1,754.555 psf 1,274.7589 psf 600 psf 0 psf I Slice 26 167.229547 ft 8.6413131 ft 0 psf 1,483.5657 psf 1,077.8736 psf 600 psf 0 psf Slice 27 71.087911 ft 7.7482202 ft 1 0 psf 1,171.165 psf 850.90121 psf 600 psf 0 psf Slice 28 74.946275 ft 6.9430213 ft 0 psf 830.26576 psf 603.22339 psf 600 psf 0 psf Slice 29 78.804638 ft 6.2245308 ft 0 psf 474.00139 psf 344.38217 psf 600 psf 0 psf Slice 30 82.663002 ft 1 5.5917086 ft 0 psf 114.05494 psf 82.865763 psf 600 psf 0 psf Report Distribution ES-8338 EMAIL ONLY Mr. Robert Magrino and Ms. Bernadette D'Souza 11913 Marine View Drive Edmonds, Washington 98026 Earth Solutions NW. LLC