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HomeMy WebLinkAboutEX_13_RS_Geotechnical_Report_010123 NELSON GEOTECHNICAL ASSOCIATES, INC. July 17, 2020 Mr. Vijay Kakubal VK Ventures, LLC VIA Email: kakubal@gmail.com Geotechnical Engineering Evaluation - REVISED Hoquiam Avenue Short Plat Development 980 Hoquiam Avenue NE Renton, Washington NGA File No. 1157020 Dear Mr. Kakubal: We are pleased to submit the attached report titled “Geotechnical Engineering Evaluation – REVISED – Hoquiam Avenue Short Plat Development – 980 Hoquiam Avenue NE – Renton, Washington.” This report summarizes our observations of the existing surface and subsurface conditions within the site, and provides general recommendations for the proposed site development. Our services were completed in general accordance with the proposal signed by you on April 14, 2020. The site consists of an irregular-shaped parcel covering approximately 2.05 acres. The site is currently occupied by a single-family residence within the northwest corner of the property. The ground surface within the property is generally relatively level to gently sloping from north to south. Vegetation within the site consists mostly of grass yard areas, moderate to densely forested areas, and ponds and wetlands areas. We understand that the proposed development plan includes removing the existing residence and subdividing the property into five separate residential lots within the northern portion of the property. We also understand that new single-family residences are proposed to be constructed within each of the lots, and frontage improvements along Hoquiam Avenue NE on the western side of the proposed development. We performed four trackhoe-excavated test pits throughout the property. During our explorations, we encountered a surficial layer of topsoil and undocumented fill material generally underlain by competent native glacial till and advance outwash soils at depth. We also performed grain size analysis on samples of the native outwash soils to determine infiltration capability of the onsite soils. It is our opinion that the proposed site development is feasible from a geotechnical engineering standpoint, provided that our recommendations for site development are incorporated into project plans. In general, the native glacial soils underlying the site should adequately support the planned structures. Foundations should be advanced through any loose soils down to the competent native bearing glacial material interpreted to underlie the site, for bearing capacity and settlement considerations. These soils should generally be encountered approximately 3.0 to 6.0 feet below the existing ground surface, based on our explorations. However, deeper areas of loose soils or undocumented fill could be encountered in unexplored areas of the site. If encountered, these soils should be removed and replaced with structural fill for foundation and pavement support. I 17311 135th Ave. N.E. Suite A-500 Woodinville, WA 98072 (425) 486-1669 www.nelsongeotech.com NELSON GEOTECHNICAL ASSOCIATES. INC.! Geotechnical Engineering Evaluation – REVISED NGA File No. 1157020 Hoquiam Avenue Short Plat Development July 17, 2020 Renton, Washington Summary - Page 2 Final stormwater plans have also not been developed, but we understand that on-site infiltration is being considered for this site. The subsurface soils generally consisted of surficial topsoil/undocumented fill soils underlain by silty fine to medium sand with varying amounts of gravel and iron-oxide weathering that we interpreted as native glacial till soils at relatively shallow depths. Underlying the native till deposits we generally encountered fine to medium sand with silt and gravel which we interpreted as advance outwash soils. Based on our laboratory testing, it is our opinion that stormwater infiltration is feasible within the native advance outwash soils within the site at depth, but not feasible or very limited within the upper glacial till. All of this has to be re-evaluated during final project planning. Additionally, shallow, low-impact design infiltration systems may also be feasible at specific areas within the site depending on final layout as determined by the civil engineer. In the attached report, we have also provided general recommendations for site grading, slabs-on- grade, and structural fill placement. We should be retained to review and comment on final development plans and observe the earthwork phase of construction. We also recommend that NGA be retained to provide monitoring and consultation services during construction to confirm that the conditions encountered are consistent with those indicated by the explorations, to provide recommendations for design changes should the conditions revealed differ from those anticipated, and to evaluate whether or not earthwork and foundation installation activities comply with contract plans and specifications. It has been a pleasure to provide service to you on this project. Please contact us if you have any questions regarding this report or require further information. Sincerely, NELSON GEOTECHNICAL ASSOCIATES, INC. Khaled M. Shawish, PE Principal Engineer NELSON GEOTECHNICAL ASSOCIATES, INC. TABLE OF CONTENTS INTRODUCTION .......................................................................................................... 1 SCOPE ........................................................................................................................ 1 SITE CONDITIONS ....................................................................................................... 2 Surface Conditions ....................................................................................................... 2 Subsurface Conditions .................................................................................................. 2 Hydrogeologic Conditions ............................................................................................ 3 LABORATORY TESTING ............................................................................................... 4 SENSITIVE AREA EVALUATION .................................................................................... 4 Seismic Hazard ............................................................................................................. 4 Erosion Hazard ............................................................................................................. 5 CONCLUSIONS AND RECOMMENDATIONS .................................................................. 5 General ......................................................................................................................... 5 Erosion Control ............................................................................................................. 6 Site Preparation and Grading ....................................................................................... 6 Temporary and Permanent Slopes............................................................................... 7 Foundations .................................................................................................................. 8 Structural Fill ................................................................................................................ 9 Slab-on-Grade .............................................................................................................. 9 Pavements .................................................................................................................. 10 Utilities ....................................................................................................................... 10 Site Drainage .............................................................................................................. 10 CONSTRUCTION MONITORING ................................................................................. 12 USE OF THIS REPORT ................................................................................................ 12 LIST OF FIGURES Figure 1 – Vicinity Map Figure 2 – Site Plan Figure 3 – Soil Classification Chart Figure 4 – Test Pit Logs Figures 5 through 7 – Grain Size Sieve Analyses NELSON GEOTECHNICAL ASSOCIATES, INC. Geotechnical Engineering Evaluation – REVISED Hoquiam Avenue Short Plat Development 980 Hoquiam Avenue NE Renton, Washington INTRODUCTION This report presents the results of our revised geotechnical engineering investigation and evaluation of the planned Hoquiam Avenue Short Plat Development project in Renton, Washington. The project site is located at 980 Hoquiam Avenue NE, as shown on the Vicinity Map in Figure 1. The purpose of this study is to explore and characterize the site’s surface and subsurface conditions and to provide geotechnical recommendations for the planned site development. The parcel is located southeast of the intersection of Hoquiam Avenue NE and NE 10th Street in the City of Renton. It is irregular in shape, but approximately square in dimension along the roadway frontage. The site is approximately 2.05 acres in area, and is currently occupied by an existing single-family residence within the northwestern portion of the property. The ground surface within the property is relatively level to gently south-sloping, and includes an enclosed depression in the southwestern portion which appears likely to be a wetland based on aerial imagery. We understand that the proposed development plan includes removing the existing residence and subdividing the property into five separate residential lots within the northern portion of the property. New single-family residences are proposed to be constructed within each of the lots, with additional frontage improvements along Hoquiam Avenue NE on the western side of the proposed development. SCOPE The purpose of this study is to explore and characterize the site surface and subsurface conditions, and provide general recommendations for site development. Specifically, our scope of services included the following: 1. A review of available soil and geologic maps of the area. 2. Exploring the subsurface soil and groundwater conditions within the site with trackhoe- excavated test pits up to 12 feet in depth, where possible. Excavation services were subcontracted by NGA. 3. Performing laboratory grain-size sieve analysis on soil samples. 4. Providing recommendations for earthwork, foundation support, and slabs-on-grade. 5. Providing recommendations for temporary and permanent slopes. Geotechnical Engineering Evaluation – REVISED NGA File No. 1157020 Hoquiam Avenue Short Plat Development July 17, 2020 Renton, Washington Page 2 NELSON GEOTECHNICAL ASSOCIATES, INC. 6. Providing recommendations for pavement subgrade, including for relevant City Street ROW improvements. 7. Providing recommendations for site drainage and erosion control. 8. Providing our opinion on the feasibility of infiltration for the onsite soils. 9. Providing recommendations for infiltration system installation. 10. Documenting the results of our findings, conclusions, and recommendations in a written geotechnical report. SITE CONDITIONS Surface Conditions The site consists of an irregular-shaped parcel covering approximately 2.05 acres. The property is currently occupied with a single-family residence within the northwest portion of the site. The ground surface within the property is generally relatively level to gently sloping from north to south. The site is covered with grass yard areas, a moderate distribution of mature trees, and a pond area localized to the southwestern portion of the property. The site is bordered to the east and south by existing residential properties, to the west by Hoquiam Avenue NE, and to the north by NE 10th Street. Although standing water was present in the pond area, we did not otherwise observe surface water throughout the proposed development portions of the site during our visit on May 19, 2020. Subsurface Conditions Geology: The geologic units for this site are shown on Geologic Map of the Renton Quadrangle, King County, Washington, by Mullineaux, D.R. (USGS, 1965). The site is mapped as glacial till (Qgt). Till is generally described as a compact, non-sorted mixture of clay, silt, sand, pebbles, cobbles, and boulders. Our explorations typically encountered undocumented fill underlain by silty fine to medium sand with varying amounts of gravel, consistent with the description of the glacial till. We also encountered fine to medium sand with varying amounts of silt and gravel which we interpreted as native advance outwash. Explorations: The subsurface conditions within the site were explored on May 19, 2020 by excavating four test pits to depths in the range of 8.5 to 11.5 feet below the existing ground surface using a trackhoe. The approximate locations of our explorations are shown on the Site Plan in Figure 2. Geologists from NGA were present during the explorations, examined the soils and geologic conditions encountered, obtained samples of the different soil types, and maintained logs of the test pits. Geotechnical Engineering Evaluation – REVISED NGA File No. 1157020 Hoquiam Avenue Short Plat Development July 17, 2020 Renton, Washington Page 3 NELSON GEOTECHNICAL ASSOCIATES, INC. The soils were visually classified in general accordance with the Unified Soil Classification System, presented in Figure 3. The logs of our test pits are attached to this report and are presented as Figure 4. We present a brief summary of the interpreted subsurface stratigraphy below. For a detailed description of the subsurface conditions, the boring logs should be reviewed. 1. Surficial, Undocumented Fill, ranging in depth between 1.0 and 3.6 feet below the existing surface and consisting of dark brown, silty, fine to medium sand with gravel, organic particulate, and roots. Encountered in variably loose to medium dense conditions. 2. Recessional Outwash Deposits, encountered in Test Pits One and Two beneath the surficial undocumented fill to a depth of 2.8 feet in Test Pit One, and to the depths explored in Test Pit Two. Consists of gray to brown, fine to coarse sand with varying amounts of silt and gravel, exposed in an increasingly medium dense condition. 3. Glacial Till, encountered as an intermediate layer in Test Pit One between 2.8 and 9.8 feet in depth, and beneath the surficial undocumented fill in Test Pits Three and Four to the depths explored. Consists of gray, silty, fine to medium sand with gravel and iron oxidation staining, especially at the upper contact of the unit. Exposed in an increasingly dense condition. 4. Advance Outwash Deposits, encountered as the basal layer of Test Pit One from a depth of 9.8 feet below existing grade to the depths explored. Consists of gray, silty, fine sand in a medium dense to dense condition. Test Pit One was completed at a depth of 12 feet below the existing ground surface within the native advance outwash deposits, and Test Pit Two was terminated within the recessional outwash at a depth of 11.5 feet. Test Pits Three and Four were terminated within the native glacial till soils at depths of 10.5 and 8.5 feet below the ground surface, respectively. Hydrogeologic Conditions During our exploration within Test Pit Three we encountered groundwater seepage at a depth of 3.6 feet below the ground surface. Pervasive iron oxidation staining was observed within Test Pit Four at the upper contact between the native glacial till and overlying undocumented fill. We interpreted these observations as evidence of a perched groundwater condition within the site. Perched water occurs when surface water infiltrates through less dense, more permeable soils and accumulates on top of relatively low permeability materials, like the glacial till encountered in Test Pits One, Three, and Four. Perched water does not represent a regional groundwater "table" within the upper soil horizons. Perched water tends to vary spatially and is Geotechnical Engineering Evaluation – REVISED NGA File No. 1157020 Hoquiam Avenue Short Plat Development July 17, 2020 Renton, Washington Page 4 NELSON GEOTECHNICAL ASSOCIATES, INC. dependent upon the amount of rainfall. We would expect the amount of perched groundwater to decrease during drier times of the year and increase during wetter periods. LABORATORY TESTING We performed three grain-size analyses on selected soil samples obtained from the test pit explorations throughout the site. Samples were obtained from Test Pit One at a depth of 10.5 feet below the existing ground surface and from Test Pit Two at depths of 5.5 and 11.5 feet below grade. Comparing the results of the grain-size analyses to the USDA textural triangle, the soils at depth in Test Pit One corresponding to our interpretation of advance outwash soils meet the classification of ‘loamy sand’ while the soils encountered within Test Pit Two, which we interpreted to be recessional outwash, meet the classification of medium sand. The results of the laboratory analysis are presented as Figures 6 through 8. SENSITIVE AREA EVALUATION Seismic Hazard We reviewed the 2018 International Building Code (IBC) for seismic site classification for this project. Since competent glacial till soils are inferred to underlie the site at depth, the site conditions best fit the IBC description for Site Class D. Table 1 below provides seismic design parameters for the site that are in conformance with the 2018 IBC, which specifies a design earthquake having a two percent probability of occurrence in 50 years (return interval of 2,475 years), and the 2008 USGS seismic hazard maps. Table 1 – 2018 IBC Seismic Design Parameters Site Class Spectral Acceleration at 0.2 sec. (g) S s Spectral Acceleration at 1.0 sec. (g) S 1 Site Coefficients Design Spectral Response Parameters F a F v S DS S D1 D 1.399 0.526 1.000 1.500 0.932 0.526 The spectral response accelerations were obtained from the USGS Earthquake Hazards Program Interpolated Probabilistic Ground Motion website (2008 data) for the project latitude and longitude. Hazards associated with seismic activity include liquefaction potential and amplification of ground motion. Liquefaction is caused by a rise in pore pressures in a loose, fine sand deposit beneath the groundwater table. It is our opinion that the medium dense or better native glacial till deposits interpreted to underlie the site have a low potential for liquefaction or amplification of ground motion. Geotechnical Engineering Evaluation – REVISED NGA File No. 1157020 Hoquiam Avenue Short Plat Development July 17, 2020 Renton, Washington Page 5 NELSON GEOTECHNICAL ASSOCIATES, INC. Erosion Hazard The criteria used for determination of erosion hazard areas include soil type, slope gradient, vegetation cover, and groundwater conditions. The erosion sensitivity is related to the vegetative cover and the specific surface soil types, which are related to the underlying geologic soil units. The Soil Survey of King County Area, Washington, by the Natural Resources Conservation Service (NRCS), was reviewed to determine the erosion hazard of the on-site soils. The site surface soils were classified using the NRCS classification system as Alderwood gravelly sandy loam, 8 to 15 percent slopes. These soils are listed as having a slight erosion hazard. It is our opinion that the erosion hazard should be low in areas with vegetated, undisturbed soil. CONCLUSIONS AND RECOMMENDATIONS General It is our opinion that the site planned development is feasible from a geotechnical standpoint. Our explorations indicated that the site is generally underlain by competent native glacial bearing soils at relatively shallow depths. The native glacial soils encountered at depth should provide adequate support for foundation, slab, and pavement loads. We recommend that the planned structures be designed utilizing shallow foundations. Footings should extend through any loose soil or undocumented fill soils and be founded on the underlying medium dense or better native glacial bearing soils, or structural fill extending to these soils. The medium dense or better native glacial bearing soils should be encountered approximately 3.0 to 6.0 feet below the existing ground surface, based on our explorations. We should note that localized areas of deeper unsuitable soils and/or undocumented fill could be encountered at this site. This condition would require additional excavations in foundation, slab, and pavement areas to remove the unsuitable soils. Based on the results of our soil explorations throughout the site, it is our opinion that the onsite native glacial till soils are not suitable for stormwater infiltration. It may be possible to utilize the native outwash soils found below the till for infiltration, provided sufficient separation can be maintained from a groundwater table or impermeable layer. Additionally, shallow, low-impact design infiltration systems may be feasible at specific areas within the site depending on final layout as determined by the civil engineer. Any planned low-impact systems should include an incorporated overflow component directed to an approved point of discharge. This is further discussed in the Site Drainage section of this report. Geotechnical Engineering Evaluation – REVISED NGA File No. 1157020 Hoquiam Avenue Short Plat Development July 17, 2020 Renton, Washington Page 6 NELSON GEOTECHNICAL ASSOCIATES, INC. Erosion Control The erosion hazard for the on-site soils is interpreted to be slight for exposed soils, but actual erosion potential will be dependent on how the site is graded and how water is allowed to concentrate. Best Management Practices (BMPs) should be used to control erosion. Areas disturbed during construction should be protected from erosion. Erosion control measures may include diverting surface water away from the stripped or disturbed areas. Silt fences and/or straw bales should be erected to prevent muddy water from leaving the site. Disturbed areas should be planted as soon as practical and the vegetation should be maintained until it is established. The erosion potential of areas not stripped of vegetation should be low. Site Preparation and Grading After erosion control measures are implemented, site preparation should consist of stripping the topsoil, undocumented fill and loose soils from foundation, slab, pavement areas, and other structural areas, to expose medium dense or better native bearing glacial till soils. The stripped soil should be removed from the site or stockpiled for later use as a landscaping fill. Based on our observations, we anticipate stripping depths of 3.0 to 6.0 feet, depending on the specific locations. However, additional stripping may be required if areas of deeper undocumented fill or loose soil are encountered within the site. After site stripping, if the exposed subgrade is deemed loose, it should be compacted to a non-yielding condition and then proof-rolled with a heavy rubber-tired piece of equipment. Areas observed to pump or weave during the proof-roll test should be reworked to structural fill specifications or over-excavated and replaced with properly compacted structural fill or rock spalls. If loose soils are encountered in the pavement areas, the loose soils should be removed and replaced with rock spalls or granular structural fill. If significant surface water flow is encountered during construction, this flow should be diverted around development areas, and the exposed subgrades should be maintained in a semi-dry condition. If wet conditions are encountered, alternative site stripping and grading techniques might be necessary. These could include using large excavators equipped with wide tracks and a smooth bucket to complete site grading and covering exposed subgrade with a layer of crushed rock for protection. If wet conditions are encountered or construction is attempted in wet weather, the subgrade should not be compacted as this could cause further subgrade disturbance. In wet conditions, it may be necessary to cover the exposed subgrade with a layer of crushed rock as soon as it is exposed to protect the moisture sensitive soils from disturbance by machine or foot traffic during construction. The prepared subgrade should be protected from construction traffic and surface water should be diverted around areas of prepared subgrade. Geotechnical Engineering Evaluation – REVISED NGA File No. 1157020 Hoquiam Avenue Short Plat Development July 17, 2020 Renton, Washington Page 7 NELSON GEOTECHNICAL ASSOCIATES, INC. The site soils are considered to be moisture-sensitive and will disturb easily when wet. We recommend that construction take place during the drier summer months if possible. However, if construction takes place during the wet season, additional expenses and delays should be expected due to the wet conditions. Additional expenses could include the need for placing a blanket of rock spalls on exposed subgrades, construction traffic areas, and paved areas prior to placing structural fill. Wet weather grading will also require additional erosion control and site drainage measures. Some of the on-site soils may be suitable for use as structural fill, depending on the moisture content of the soil at the time of construction. NGA should be retained to evaluate the suitability of all on-site and imported structural fill material during construction. Temporary and Permanent Slopes Temporary cut slope stability is a function of many factors, including the type and consistency of soils, depth of the cut, surcharge loads adjacent to the excavation, length of time a cut remains open, and the presence of surface or groundwater. It is exceedingly difficult under these variable conditions to estimate a stable, temporary, cut slope angle. Therefore, it should be the responsibility of the contractor to maintain safe slope configurations at all times as indicated in OSHA guidelines for cut slopes. The following information is provided solely for the benefit of the owner and other design consultants and should not be construed to imply that Nelson Geotechnical Associates, Inc. assumes responsibility for job site safety. Job site safety is the sole responsibility of the project contractor. For planning purposes, we recommend that temporary cuts in the upper undocumented fill soils be no steeper than 2 Horizontal to 1 Vertical (2H:1V). Temporary cuts in the competent native glacial soils at depth should be no steeper than 1.5H:1V. If significant groundwater seepage or surface water flow were encountered, we would expect that flatter inclinations would be necessary. We recommend that cut slopes be protected from erosion. The slope protection measures may include covering cut slopes with plastic sheeting and diverting surface runoff away from the top of cut slopes. We do not recommend vertical slopes for cuts deeper than four feet, if worker access is necessary. We recommend that cut slope heights and inclinations conform to appropriate OSHA/WISHA regulations. Permanent cut and fill slopes should be no steeper than 2H:1V. However, flatter inclinations may be required in areas where loose soils are encountered. Permanent slopes should be vegetated and the vegetative cover maintained until established. Geotechnical Engineering Evaluation – REVISED NGA File No. 1157020 Hoquiam Avenue Short Plat Development July 17, 2020 Renton, Washington Page 8 NELSON GEOTECHNICAL ASSOCIATES, INC. Foundations Conventional shallow spread foundations should be placed on medium dense or better native bearing glacial till soils, or be supported on structural fill or rock spalls extending to those soils. Medium dense or better bearing soils should be encountered approximately 3.0 feet below ground surface based on our explorations. Where undocumented fill or less dense soils are encountered at footing bearing elevation, the subgrade should be over-excavated to expose suitable bearing soil. The over-excavation may be filled with structural fill, or the footing may be extended down to the competent native soils. If footings are supported on structural fill, the fill zone should extend outside the edges of the footing a distance equal to one half of the depth of the over-excavation below the bottom of the footing. Footings should extend at least 18 inches below the lowest adjacent finished ground surface for frost protection and bearing capacity considerations. Foundations should be designed in accordance with the 2018 IBC. Footing widths should be based on the anticipated loads and allowable soil bearing pressure. Water should not be allowed to accumulate in footing trenches. All loose or disturbed soil should be removed from the foundation excavation prior to placing concrete. For foundations constructed as outlined above, we recommend an allowable bearing pressure of not more than 2,000 pounds per square foot (psf) be used for the design of footings founded on the medium dense or better native bearing soils or structural fill extending to the competent native bearing material. The foundation bearing soil should be evaluated by a representative of NGA. We should be consulted if higher bearing pressures are needed. Current IBC guidelines should be used when considering increased allowable bearing pressure for short-term transitory wind or seismic loads. Potential foundation settlement using the recommended allowable bearing pressure is estimated to be less than 1-inch total and ½-inch differential between adjacent footings or across a distance of about 20 feet, based on our experience with similar projects. Lateral loads may be resisted by friction on the base of the footing and passive resistance against the subsurface portions of the foundation. A coefficient of friction of 0.35 may be used to calculate the base friction and should be applied to the vertical dead load only. Passive resistance may be calculated as a triangular equivalent fluid pressure distribution. An equivalent fluid density of 200 pounds per cubic foot (pcf) should be used for passive resistance design for a level ground surface adjacent to the footing. This level surface should extend a distance equal to at least three times the footing depth. These recommended values incorporate safety factors of 1.5 and 2.0 applied to the estimated ultimate values for frictional and passive resistance, respectively. To achieve this value of passive resistance, the foundations should be poured “neat” against the native medium dense soils or compacted fill should be used as backfill against the front of the footing. We recommend that the upper one foot of soil be neglected when calculating the passive resistance. Geotechnical Engineering Evaluation – REVISED NGA File No. 1157020 Hoquiam Avenue Short Plat Development July 17, 2020 Renton, Washington Page 9 NELSON GEOTECHNICAL ASSOCIATES, INC. Structural Fill General: Fill placed beneath foundations, pavement, or other settlement-sensitive structures should be placed as structural fill. Structural fill, by definition, is placed in accordance with prescribed methods and standards, and is monitored by an experienced geotechnical professional or soils technician. Field monitoring procedures would include the performance of a representative number of in-place density tests to document the attainment of the desired degree of relative compaction. The area to receive the fill should be suitably prepared as described in the Site Preparation and Grading subsection prior to beginning fill placement. Materials: Structural fill should consist of a good quality, granular soil, free of organics and other deleterious material, and be well graded to a maximum size of about three inches. All-weather fill should contain no more than five-percent fines (soil finer than U.S. No. 200 sieve, based on that fraction passing the U.S. 3/4-inch sieve). Some of the more granular on-site soils may be suitable for use as structural fill, but this will be highly dependent on the moisture content of these soils at the time of construction. We should be retained to evaluate all proposed structural fill material prior to placement. Fill Placement: Following subgrade preparation, placement of structural fill may proceed. All filling should be accomplished in uniform lifts up to eight inches thick. Each lift should be spread evenly and be thoroughly compacted prior to placement of subsequent lifts. All structural fill underlying building areas and pavement subgrade should be compacted to a minimum of 95 percent of its maximum dry density. Maximum dry density, in this report, refers to that density as determined by the ASTM D-1557 Compaction Test procedure. The moisture content of the soils to be compacted should be within about two percent of optimum so that a readily compactable condition exists. It may be necessary to over-excavate and remove wet soils in cases where drying to a compactable condition is not feasible. All compaction should be accomplished by equipment of a type and size sufficient to attain the desired degree of compaction and should be tested. Slab-on-Grade Slab-on-grade should be supported on subgrade soils prepared as described in the Site Preparation and Grading subsection of this report. We recommend that all floor slabs be underlain by at least six inches of free- draining gravel with less than three percent by weight of the material passing Sieve #200 for use as a capillary break. A suitable vapor barrier, such as heavy plastic sheeting (6-mil, minimum), should be placed over the capillary break material. An additional 2-inch-thick moist sand layer may be used to cover the vapor barrier. This sand layer may be used to protect the vapor barrier membrane and to aid in curing the concrete. Geotechnical Engineering Evaluation – REVISED NGA File No. 1157020 Hoquiam Avenue Short Plat Development July 17, 2020 Renton, Washington Page 10 NELSON GEOTECHNICAL ASSOCIATES, INC. Pavements Pavement subgrade preparation and structural filling where required, should be completed as recommended in the Site Preparation and Grading and Structural Fill subsections of this report. The pavement subgrade should be proof-rolled with a heavy, rubber-tired piece of equipment, to identify soft or yielding areas that require repair. The pavement section should be underlain by a stable subgrade. We should be retained to observe the proof-rolling and recommend repairs prior to placement of the asphalt or hard surfaces. Utilities We recommend that underground utilities be bedded with a minimum six inches of pea gravel prior to backfilling the trench with on-site or imported material. Trenches within settlement sensitive areas should be compacted to 95 percent of the modified proctor as described in the Structural Fill subsection of this report. Trenches located in non-structural areas should be compacted to a minimum 90 percent of the maximum dry density. The trench backfill compaction should be tested. Site Drainage Stormwater Infiltration Feasibility: During our exploration within Test Pit Three we encountered groundwater seepage at a depth of 3.6 feet below the ground surface. Pervasive iron oxidation staining was observed within Test Pit Four at the upper contact between the native glacial till and overlying undocumented fill. We interpreted these observations as evidence of a perched groundwater condition within the site. It is likely that traditional stormwater infiltration may be infeasible within the dense glacial till soils encountered at intermediate depths within Test Pits One, Three, and Four. However, significant recessional outwash deposits, which correspond to a classification of ‘medium sand,’ encountered in Test Pit Two should support full infiltration in accordance with the 2017 City of Renton Surface Water Design Manual. Additionally, depending on project design, full infiltration should be acceptable for the material we interpreted as advance outwash encountered at depth in Test Pit One. Full infiltration should be possible, provided sufficient separation from a potential groundwater table is met by the project design, which was not encountered at the depths explored within the scope of this evaluation. In either case, full infiltration should include an overflow component in the design directed to disperse into the nearby wetland or an existing system, if applicable. We should be retained to confirm soils exposed in excavations are consistent with our recommendations during construction as well. Geotechnical Engineering Evaluation – REVISED NGA File No. 1157020 Hoquiam Avenue Short Plat Development July 17, 2020 Renton, Washington Page 11 NELSON GEOTECHNICAL ASSOCIATES, INC. Low impact design infiltration systems, such as rain gardens, bio-retention planters, or pervious pavements may also be used within the site if a suitable overflow component is included in the design. We recommend the base of any low-impact infiltration systems be advanced through the upper undocumented fill soils and be founded within the native soils found at depth. Additionally, we recommend any low-impact design systems within the site have an incorporated overflow component directed towards an approved point-of-discharge. If desired, we recommend that permeable pavement surfacing be underlain by a minimum of 12 inches of clean crushed rock with competent native soils below. We recommend that any proposed low-impact infiltration systems such as pervious pavements be placed as to not negatively impact any proposed or existing nearby structures and also meet all required setbacks from existing property lines, structures, and sensitive areas as discussed in the drainage manual. In general, infiltration systems should not be located within proposed fill areas within the site, such as those associated with site grading or retaining wall backfill, as such conditions could lead to failures of the placed fills and/or retaining structures. We should be retained to review pavement design and oversee installation. All stormwater management systems within this site should be sized and designed in accordance with the 2017 City of Renton Surface Water Design Manual. We recommend that any proposed stormwater management systems be located as to not negatively impact any proposed or existing nearby structures and/or properties and also meet all required setbacks from existing property lines, structures, and sensitive areas in accordance with the stormwater manual. Surface Drainage: The finished ground surface should be graded such that stormwater is directed to an approved stormwater collection system. Water should not be allowed to stand in any areas where footings, slabs, or pavements are to be constructed. Final site grades should allow for drainage away from the residence. We suggest that the finished ground be sloped downward at a minimum gradient of three percent, for a distance of at least 10 feet away from the residence. Surface water should be collected by permanent catch basins and drain lines, and be discharged into an approved discharge system. Subsurface Drainage: If groundwater is encountered during construction, we recommend that the contractor slope the bottom of the excavation and collect the water into ditches and small sump pits where the water can be pumped out and routed into a permanent storm drain. Geotechnical Engineering Evaluation – REVISED NGA File No. 1157020 Hoquiam Avenue Short Plat Development July 17, 2020 Renton, Washington Page 12 NELSON GEOTECHNICAL ASSOCIATES, INC. We recommend the use of footing drains around the structures. Footing drains should be installed at least one foot below planned finished floor elevation. The drains should consist of a minimum 4-inch-diameter, rigid, slotted or perforated, PVC pipe surrounded by free-draining material wrapped in a filter fabric. We recommend that the free-draining material consist of an 18-inch-wide zone of clean (less than three-percent fines), granular material. Pea gravel is an acceptable drain material. The free-draining material should extend to one foot below the finished surface. The top foot of backfill should consist of impermeable soil placed over plastic sheeting or building paper to minimize surface water or fines migration into the footing drain. Footing drains should discharge into tightlines leading to an approved collection and discharge point with convenient cleanouts to prolong the useful life of the drains. Roof drains should not be connected to wall or footing drains. CONSTRUCTION MONITORING We should be retained to provide construction monitoring services during the earthwork phase of the project to evaluate subgrade conditions, temporary cut conditions, fill compaction, and drainage system installation. USE OF THIS REPORT NGA has prepared this report for Mr. Vijay Kakubal and his agents, for use in the planning and design of the development on this site only. The scope of our work does not include services related to construction safety precautions and our recommendations are not intended to direct the contractors’ methods, techniques, sequences, or procedures, except as specifically described in our report for consideration in design. There are possible variations in subsurface conditions between the explorations and also with time. Our report, conclusions, and interpretations should not be construed as a warranty of subsurface conditions. A contingency for unanticipated conditions should be included in the budget and schedule. We recommend that NGA be retained to provide monitoring and consultation services during construction to confirm that the conditions encountered are consistent with those indicated by the explorations, to provide recommendations for design changes should the conditions revealed differ from those anticipated, and to evaluate whether or not earthwork and foundation installation activities comply with contract plans and specifications. We should be contacted a minimum of one week prior to construction activities and could attend pre-construction meetings if requested. Within the limitations of scope, schedule, and budget, our services have been performed in accordance with generally accepted geotechnical engineering practices in effect in this area at the time this report was prepared. No other warranty, expressed or implied, is made. Our observations, findings, and opinions are a means to identify and reduce the inherent risks to the owner. o-o-o Not to Scale VICINITY MAP Hoquiam Ave Short Plat Vicinity Map Project Site 1 No.Project Number Date By CKRevision Geotechnical Engineers & Geologists Nelson Geotechnical Associates, Inc.NG A Woodinville Office 17311-135th Ave. NE, A-500 Woodinville, WA 98072 (425) 486-1669 / Fax: 481-2510 East Wenatchee Office 5526 Industry Lane, #2 East Wenatchee, WA 98802 (509) 665-7696 / Fax: 665-7692www.nelsongeotech.com \\HILL\company\2020 NGA Project Folders\11570-20 Hoquiam Ave SP Renton\Drafting\VM.dwg5/20/20 DPN CTCOriginal Figure 1 1157020 Renton, WA A N (H ft isrnuir-'*Little Orca Daycare tj NE 171h St v"',sec*c£l9 99Valvoline Instant Oil Change NE 17th St ■Creative Microsystems 9@)RdSfStarbucks ^(*») 9Renton Licensing Services Office •£ Z3I9^Albertsons ft«>--Z @) S © NE 12lh St °NE 12th SI NE 12th,NE 12lhSt SE 112th St>SE 112th St n High School ^Hazenm SE 113th St NE 11thNE 11th St x^nthst / SE 114th St •r ><&NE 10th PI Esplanade ^ SE 116th St -v;.s s I ffi NE 10th SI <NE 1 Oth St SE 116th StOth Ln V/> -■><iSt NE 9th Ct %?rb SE 117th Ave1NE %, f> NE’WlSl £9Rockin' Horse Dance Barn 2 9 Honey Dew Athletic Fields S>-Kiwanis Park%r- NE 8th PIJkIi5 Alicia's Wonderland II ^5NE 81h Si ?> NE 7th PI 2 •:Hi 7th St He II J">p, NE 71h SI Weston Heights ft by RM Homes ▼\ Forestview ^^TthSt 3- : ^ Church Of Simplex2 SaintsZ NE 6th St NE 6th St -NE 6th St NEW"512v NE 5th O. The Windsor©INE 5t/> Pi E os (X tnNE 5th Pt 3 $ ©QFCSafeway Q > ? >-ft9>wn Pointe s »I NE4thCt > ft m ^ Chuck's Donuts < King County ft Water District #90 ▼m NE 4th PI -VE 4th PIUnited States Postal Service WHITMAN COURT ^ Carl s JrNE 4th st plewood Park ^ NE 4th St NE 4th St Lord o Lutheran Ct e.!z NE 3rd PI NE 3rd ct £s >NE 3rd$.< NE 3rd C* . I—C >z z5m*<5 %Heritage Park *NE 2nd Pt 2nd P Geotechnical Engineering Evaluation – REVISED NGA File No. 1157020 Hoquiam Avenue Short Plat Development July 17, 2020 Renton, Washington Page 13 NELSON GEOTECHNICAL ASSOCIATES, INC. It has been a pleasure to provide service to you on this project. If you have any questions or require further information, please call. Sincerely, NELSON GEOTECHNICAL ASSOCIATES, INC. Daniel J. O’Dell Staff Geologist Carston T. Curd, GIT Project Geologist Khaled M. Shawish, PE Principal DJO:CTC:KMS:dy Eight Figures Attached SI zst/S'«7/03» ■'y&AV*■I/^i\ (£<\jyurrj’^jovtr^/^yiASP's/ Hoquiam Ave Short Plat Site Plan 1 No.Project Number Date By CKRevision Geotechnical Engineers & Geologists Nelson Geotechnical Associates, Inc.NG A Woodinville Office 17311-135th Ave. NE, A-500 Woodinville, WA 98072 (425) 486-1669 / Fax: 481-2510 East Wenatchee Office 5526 Industry Lane, #2 East Wenatchee, WA 98802 (509) 665-7696 / Fax: 665-7692www.nelsongeotech.com \\HILL\company\2020 NGA Project Folders\11570-20 Hoquiam Ave SP Renton\Drafting\SP.dwg5/20/20 DPN CTCOriginal Figure 2 1157020 Site Plan Reference: Site Plan based on a plan dated May 12, 2020 titled "Topographic Survey for VK Ventures," prepared by Tyee Surveyors. LEGEND TP-1 Number and approximate location of test pit Property line Existing Residence NE 10th St Hoquiam Ave NEScale: 1 inch = 60 feet 0 60 120 TP-4 TP-3 TP-2 TP-1 oXQdQdBOARD FENCEdo oA-,30'OC“I>8-0Wl 3N >/!• MS >/l 3N Z/l M 3NI7 ’3TfFFdoQ(?5Q QN,1VOd10<0\XY.2: iSa .Op':da' iQdi■2,xjlOoo „I%■InQd<dCMo5"8Sfc\dindI J9 0co od,9.5ooQd c3ddu[Ii -ddoi■M-{7i> >2i idI>. .in□V QIPJ'd-j<o1emo>DoEiO*'dor6 7o uT-r&oii<oO'fa//X21/dCO<<: -in/ l©\fc-°d../■r-Qd/*>ao/O’(Ai iAor.d$■*•0°'/inox\o:z\::<x"■Qd\\COO'nAlQ40EIOcOJof■yXo\\c>\- JXflXX<a>' ■c 3_IS\H^r\%\>.A" >;o°0) <? "d-xAj0\\Q<P-a\7 s.\COa*>\<v i12 +i.1.14Xj oo Q\>loAx5X->dd"Vcooo-oe /Ps0. tl.o'-0d> <p„A®iXIAVII4■JXZ£1:V' rcnIzoCD<>8:3o>4Ain-7■QA-~IC.9"VTMufcL10J-70 J'5cS1^A; oiPi9%Ax-LO-A<B±<A-703oCDTTA0CTT"0I0J~L> *- r-XII□CO' > 3=d 0- 0.oiI■Cm>za ixCL-M-/I GW GP GM GC SW SP SM SC ML CL OL MH CH OH PT PEAT ORGANIC CLAY, ORGANIC SILT CLAY OF HIGH PLASTICITY, FAT CLAY SILT OF HIGH PLASTICITY, ELASTIC SILT SILTY SAND SILT ORGANIC SILT, ORGANIC CLAY CLAY CLAYEY SAND POORLY GRADED SAND WELL-GRADED SAND, FINE TO COARSE SAND CLAYEY GRAVEL SILTY GRAVEL POORLY-GRADED GRAVEL WELL-GRADED, FINE TO COARSE GRAVELCLEAN GRAVEL GRAVEL WITH FINES CLEAN SAND SAND WITH FINES INORGANIC ORGANIC INORGANIC ORGANIC HIGHLY ORGANIC SOILS GRAVEL SAND SILT AND CLAY SILT AND CLAY MORE THAN 50 % OF COARSE FRACTION RETAINED ON NO. 4 SIEVE PASSES NO. 4 SIEVE LIQUID LIMIT LESS THAN 50 % 50 % OR MORE LIQUID LIMIT MORE THAN 50 % OF COARSE FRACTION COARSE - GRAINED SOILS FINE - GRAINED SOILS MORE THAN 50 % RETAINED ON NO. 200 SIEVE PASSES NO. 200 SIEVE MORE THAN 50 % MAJOR DIVISIONS GROUP SYMBOL GROUP NAME UNIFIED SOIL CLASSIFICATION SYSTEM NOTES: 1) Field classification is based on visual examination of soil in general accordance with ASTM D 2488-93. 2) Soil classification using laboratory tests is based on ASTM D 2488-93. 3) Descriptions of soil density or consistency are based on interpretation of blowcount data, visual appearance of soils, and/or test data. SOIL MOISTURE MODIFIERS: Dry - Absence of moisture, dusty, dry to the touch Moist - Damp, but no visible water. Wet - Visible free water or saturated, usually soil is obtained from below water table 1 No.Project Number Date By CKRevision Geotechnical Engineers & Geologists Nelson Geotechnical Associates, Inc.NG A Woodinville Office 17311-135th Ave. NE, A-500 Woodinville, WA 98072 (425) 486-1669 / Fax: 481-2510 East Wenatchee Office 5526 Industry Lane, #2 East Wenatchee, WA 98802 (509) 665-7696 / Fax: 665-7692www.nelsongeotech.com \\HILL\company\2020 NGA Project Folders\11570-20 Hoquiam Ave SP Renton\Drafting\SC.dwgFigure 3 1157020 5/20/20 DPN CTCOriginal Hoquiam Ave Short Plat Soil Classification Chart LOG OF EXPLORATION DEPTH (FEET) USC SOIL DESCRIPTION DJO:CTC NELSON GEOTECHNICAL ASSOCIATES, INC. NGA FILE 1157020 FIGURE 4 TEST PIT ONE 0.0 – 0.5 DARK BROWN, SILTY, FINE TO MEDIUM SAND WITH ORGANICS, GRAVEL, ROOTS, AND IRON OXIDATION STAINING (LOOSE TO MEDIUM DENSE, MOIST) (UNDOCUMENTED FILL) 0.5 – 1.0 RED-BROWN, SILTY, FINE TO MEDIUM SAND WITH TRACE ROOTS, AND IRON OXIDATION STAINING (LOOSE TO MEDIUM DENSE, MOIST) (UNDOCUMENTED FILL) 1.0 – 2.5 SM TAN TO GRAY, SILTY, FINE TO MEDIUM SAND WITH TRACE ROOTS, TRACE, GRAVEL, AND IRON OXIDATION STAINING (MEDIUM DENSE, MOIST) 2.5 – 2.8 SP-SM ORANGE TO ORANGE-BROWN, FINE TO COARSE SAND WITH SILT, GRAVEL, ROOTS, AND IRON OXIDATION STAINING (MEDIUM DENSE, MOIST) (RECESSIONAL OUTWASH) 2.8 – 9.8 SM GRAY, SILTY, FINE TO MEDIUM SAND WITH GRAVEL AND IRON OXIDATION STAINING (MEDIUM DENSE TO DENSE, MOIST) (GLACIAL TILL) 9.8 – 12.0 SM GRAY TO GRAY-BROWN, SILTY, FINE SAND (MEDIUM DENSE TO DENSE, MOIST) (ADVANCE OUTWASH) SAMPLE WAS COLLECTED AT 10.5 FEET GROUNDWATER SEEPAGE WAS NOT ENCOUNTERED TEST PIT CAVING WAS NOT ENCOUNTERED TEST PIT TERMINATED AT 12 FEET ON 05/19/20 TEST PIT TWO 0.0 – 0.5 DARK BROWN, SILTY, FINE TO MEDIUM SAND WITH ORGANICS, GRAVEL, ROOTS, AND IRON OXIDATION STAINING (LOOSE TO MEDIUM DENSE, MOIST) 0.5 – 3.5 BROWN TO DARK BROWN SILTY, FINE TO MEDIUM SAND WITH GRAVEL, METAL DEBRIS, ROOTS, AND ORGANICS (LOOSE TO MEDIUM DENSE, MOIST) (UNDOCUMENTED FILL) 3.5 – 6.0 SP-SM BROWN TO ORANGE BROWN, FINE TO MEDIUM SAND WITH SILT, CHARCOAL, GRAVEL, TRACE IRON OXIDE WEATHERING, AND ROOTS (LOOSE TO MEDIUM DENSE, MOIST) (WEATHERED RECESSIONAL OUTWASH) 6.0 – 11.5 SP-SM GRAY TO GRAY-BROWN, FINE TO COARSE SAND WITH GRAVEL, SILT, AND TRACE IRON OXIDE STAINING (MEDIUM DENSE TO DENSE, MOIST) (RECESSIONAL OUTWASH) SAMPLES WERE COLLECTED AT 5.5, 9.0, AND 11.5 FEET GROUNDWATER SEEPAGE WAS NOT ENCOUNTERED TEST PIT CAVING WAS NOT ENCOUNTERED TEST PIT WAS COMPLETED AT 11.5 FEET ON 05/19/20 TEST PIT THREE 0.0 – 1.3 DARK BROWN, SILTY, FINE TO MEDIUM SAND WITH ORGANICS, GRAVEL, ROOTS, AND IRON OXIDATION STAINING (LOOSE TO MEDIUM DENSE, MOIST) 1.3 – 3.6 ORANGE BROWN TO BROWN, SILTY, FINE TO MEDIUM SAND WITH ROOTS, GRAVEL, ORGANICS, AND IRON OXIDATION STAINING (LOOSE TO MEDIUM DENSE, MOIST TO WET) (UNDOCUMENTED FILL) 3.6 – 7.5 SM GRAY TO ORANGE BROWN, SILTY FINE TO MEDIUM SAND WITH GRAVEL, AND IRON OXIDATION STAINING (MEDIUM DENSE, MOIST TO WET) (WEATHERED GLACIAL TILL) 7.5 – 10.5 SM GRAY TO ORANGE-GRAY, SILTY FINE TO MEDIUM SAND WITH GRAVEL AND TRACE IRON OXIDATION STAINING (MEDIUM DENSE TO DENSE, MOIST) (GLACIAL TILL) SAMPLES WERE COLLECTED AT 6.5, AND 10.5 FEET GROUNDWATER SEEPAGE WAS ENCOUNTERED AT 3.6 FEET TEST PIT CAVING WAS NOT ENCOUNTERED TEST PIT WAS COMPLETED AT 10.5 FEET ON 05/19/20 LOG OF EXPLORATION DEPTH (FEET) USC SOIL DESCRIPTION DJO:CTC NELSON GEOTECHNICAL ASSOCIATES, INC. NGA FILE 1157020 FIGURE 5 TEST PIT FOUR 0.0 – 0.9 DARK BROWN, SILTY, FINE TO MEDIUM SAND WITH ORGANICS, GRAVEL, ROOTS, AND IRON OXIDE STAINING. (LOOSE TO MEDIUM DENSE, MOIST) 0.9 – 3.2 ORANGE BROWN TO BROWN, SILTY, FINE TO MEDIUM SAND WITH ROOTS, GRAVEL, ORGANICS, AND IRON OXIDE WEATHERING (LOOSE TO MEDIUM DENSE, MOIST) (UNDOCUMENTED FILL) 3.2 – 4.3 SM GRAY TO GRAY-BROWN, SILTY, FINE TO MEDIUM SAND WITH GRAVEL, IRON OXIDATION STAINING, AND TRACE ROOTS (MEDIUM DENSE, MOIST) (WEATHERED GLACIAL TILL) 4.3 – 8.5 SM GRAY, SILTY, FINE TO MEDIUM SAND WITH GRAVEL AND TRACE IRON OXIDE STAINING (MEDIUM DENSE TO DENSE, MOIST) (GLACIAL TILL) SAMPLES WERE COLLECTED AT 4.0 AND 8.5 FEET GROUNDWATER SEEPAGE WAS NOT ENCOUNTERED TEST PIT CAVING WAS NOT ENCOUNTERED TEST PIT MET REFUSAL AT 8.5 FEET ON 05/19/20 GRAIN SIZE IN MILLIMETERSPERCENT FINER BY WEIGHT1000 100 10 1.0 0.1 0.01 0.001 0 20 10 30 50 40 60 80 70 90 100 SOIL DESCRIPTIONSAMPLE DEPTH EXPLORATION NUMBER U.S.C. SYMBOL SOIL DISTRIBUTION3/4 IN.3/8 IN.NO. 4NO. 10NO. 20NO. 40NO. 60NO. 100NO. 200 COBBLES GRAVEL COARSE SAND FINE COARSE MEDIUM FINE SILT OR CLAY U.S. STANDARD SIEVE SIZE 1No.Project NumberDateByCKRevisionNelson GeotechnicalAssociates, Inc.Geotechnical Engineers & GeologistsGNAWoodinville Office17311-135th Ave. NE, A-500Woodinville, WA 98072(425) 486-1669 / Fax: 481-2510East Wenatchee Office5526 Industry Lane, #2East Wenatchee, WA 98802(509) 665-7696 / Fax: 665-7692www.nelsongeotech.com\\HILL\company\2020 NGA Project Folders\11570-20 Hoquiam Ave SP Renton\Drafting\Sieve.dwgFigure 611570206/2/20DPNAJSOriginal Gravel = 0% Sand = 57% Silt/Clay = 43% Silty, fine sandTP-1 10.5 feetSMHoquiam Ave Short PlatSieve Analysis#- \t GRAIN SIZE IN MILLIMETERSPERCENT FINER BY WEIGHT1000 100 10 1.0 0.1 0.01 0.001 0 20 10 30 50 40 60 80 70 90 100 SOIL DESCRIPTIONSAMPLE DEPTH EXPLORATION NUMBER U.S.C. SYMBOL SOIL DISTRIBUTION3/4 IN.3/8 IN.NO. 4NO. 10NO. 20NO. 40NO. 60NO. 100NO. 200 COBBLES GRAVEL COARSE SAND FINE COARSE MEDIUM FINE SILT OR CLAY U.S. STANDARD SIEVE SIZE 1No.Project NumberDateByCKRevisionNelson GeotechnicalAssociates, Inc.Geotechnical Engineers & GeologistsGNAWoodinville Office17311-135th Ave. NE, A-500Woodinville, WA 98072(425) 486-1669 / Fax: 481-2510East Wenatchee Office5526 Industry Lane, #2East Wenatchee, WA 98802(509) 665-7696 / Fax: 665-7692www.nelsongeotech.com\\HILL\company\2020 NGA Project Folders\11570-20 Hoquiam Ave SP Renton\Drafting\Sieve.dwgFigure 711570206/2/20DPNAJSOriginal Gravel = 25% Sand = 64% Silt/Clay = 11% Fine to medium sand with silt and gravel TP-2 5.5 feetSP-SMHoquiam Ave Short PlatSieve Analysis#- \t GRAIN SIZE IN MILLIMETERSPERCENT FINER BY WEIGHT1000 100 10 1.0 0.1 0.01 0.001 0 20 10 30 50 40 60 80 70 90 100 SOIL DESCRIPTIONSAMPLE DEPTH EXPLORATION NUMBER U.S.C. SYMBOL SOIL DISTRIBUTION3/4 IN.3/8 IN.NO. 4NO. 10NO. 20NO. 40NO. 60NO. 100NO. 200 COBBLES GRAVEL COARSE SAND FINE COARSE MEDIUM FINE SILT OR CLAY U.S. STANDARD SIEVE SIZE 1No.Project NumberDateByCKRevisionNelson GeotechnicalAssociates, Inc.Geotechnical Engineers & GeologistsGNAWoodinville Office17311-135th Ave. NE, A-500Woodinville, WA 98072(425) 486-1669 / Fax: 481-2510East Wenatchee Office5526 Industry Lane, #2East Wenatchee, WA 98802(509) 665-7696 / Fax: 665-7692www.nelsongeotech.com\\HILL\company\2020 NGA Project Folders\11570-20 Hoquiam Ave SP Renton\Drafting\Sieve.dwgFigure 811570206/2/20DPNAJSOriginal Gravel = 42% Sand = 52% Silt/Clay = 6% Fine to coarse sand with silt and gravel TP-2 11.5 feetSP-SMHoquiam Ave Short PlatSieve Analysis\\