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Geotechnical Engineering Report - GRD Engineering / Geo-Tech Reports - 5/14/2020
• t now LU RILEYGROUP May 14, 2020 David Overton E. E. Overton PO Box 1477 Tacoma, Washington 98401 Subject: Geotechnical Engineering Report Olympic Ridge State Highway 3 Belfair► Washington ton RGI Project No. 2020-007-1 Dear Mr. Overton: As requested,The Riley Group, Inc. (RGI)has performed a Geotechnical Engineering Report (GER) for the Olympic Ridge project located at State Highway 3, Belfair, Washington. Our services were completed in accordance with our proposal 2020-007-PRP1 dated January 8, 2020 and authorized by you on January 8, 2020. The information in this GER is based on our understanding of the proposed construction, and the soil and groundwater conditions encountered in the test pits completed by RGI at the site on April 9, 2020. RGI recommends that you submit the project plans and specifications to RGI for a general review so that we may confirm that the recommendations in this GER are interpreted and Implemented properly in the construction documents. RGI also recommends that a representative of our firm be present on site during portions of the project construction to confirm that the soil and groundwater conditions are consistent with those that form the basis for the engineering recommendations in this GER. If you have any questions or require additional information, please contact us. Respectfully submitted, THE RILEY GROUP, INC. o� Wa shy to � P►'h�tC �+- y`a o' oQ WAsy��Q 'k` I co 0� 2698 Sed Ge ° `1ZoT.c G S�ONAL ERIC L. WOODS 6-/�/�/ZG Z& Eric L. Woods, LG Kristina M. Weller, PE Project Geologist Principal Geotechnical Engineer Corporate Office 17522 Bothell Way Northeast Bothell,Washington 98011 Phone 425.415.0551•Fox 425.415.0311 www✓iley-group.coin t Geotechnical Engineering Report i May 14,1010 Olympic Ridge,Belfair,Washington RGI Project No.1010.007-1 TABLE OF CONTENTS 1.0 INTRODUCTION............................................................................................................................... 1 2.0 PROJECT I)ESCRIPTION............................................................................................................... 1 3.0 FIELD EXPLORATION AND LABORATORY TESTING.......................................................... 1 3.1 FIELD EXPLORATION...................................................................................................................................1 3.2 LABORATORY TESTING................................................................................................................................2 4.0 SITE CONDITIONS...........................................................................................................................2 4.1 SURFACE..................................................................................................................................................2 4.2 GEOLOGY.................................................................................................................................................3 4.3 SoILs.......................................................................................................................................................3 4.4 GROUNDWATER........................................................................................................................................3 4.5 SEISMIC CONSIDERATIONS...........................................................................................................................4 4.6 GEOLOGIC HAZARD AREAS..........................................................................................................................5 4.6.1 Erosion Hazard Areas...................................................................................................................5 4.6.2 Geologically Hazardous Areas......................................................................................................5 4.6.3 Slope Reconnaissance..................................................................................................................5 4.6.4 Recommendations.......................................................................................................................5 5.0 DISCUSSION AND RECOMMENDATIONS.................................................................................6 5.1 GEOTECHNICAL CONSIDERATIONS.................................................................................................................6 5.2 EARTHWORK.............................................................................................................................................6 5.2.1 Erosion and Sediment Control.....................................................................................................6 5.2.2 Stripping.......................................................................................................................................7 5.2.3 Excavations...................................................................................................................................8 5.2.4 Site Preparation............................................................................... .......................................8 5.2.5 Structural Fill................................................................................................................................9 5.2.6 Cut and Fill Slopes......................................................................................................................11 5.2.7 Wet Weather Construction Considerations...............................................................................11 5.3 FOUNDATIONS........................................................................................................................................12 5.4 RETAINING WALLS...................................................................................................................................12 5.5 SLAB-ON-GRADE CONSTRUCTION...............................................................................................................13 5.6 DRAINAGE..............................................................................................................................................14 5.6.1 Surface.......................................................................................................................................14 5.6.2 Subsurface..................................................................................................................................14 5.6.3 Infiltration..................................................................................................................................14 5.6.4 Stormwater Detention Pond......................................................................................................14 5.7 UTILITIES................................................................................................................................................14 5.8 PAVEMENTS............................................................................................................................................15 6.0 ADDITIONAL SERVICES..............................................................................................................15 7.0 LIMITATIONS.................................................................................................................................16 L- RILEYGROUP Geotechnkol Engineering Report li May 24,2020 Olympic Ridge,eeffoir,Woshington RGl project No.2020-007-1 LIST OF FIGURES AND APPENDICES Figure1.....................................................................................................................Site Vicinity Map Figure2...............................................................................................Geotechnical Exploration Plan Figure3................................................................................................................Slopes and Geology Figure4..................................................................................................................Cross-Section A-A' Figure 5...............................................................................................Retaining Wall Drainage Detail Figure6....................................................................................................Typical Footing Drain Detail Appendix A..........................................................................Field Exploration and Laboratory Testing @go L- RILEYGROUP Geotechnicol Engineering Report ii May 14,2020 Olympic Ridge,Selfair,Washington RGl Project No.2020-007-1 Executive Summary This Executive Summary should be used in conjunction with the entire Geotechnical Engineering Report (GER)for design and/or construction purposes. It should be recognized that specific details were not included or fully developed in this section, and the GER must be read in its entirety for a comprehensive understanding of the items contained herein. Section 7.0 should be read for an understanding of limitations. RGI's geotechnical scope of work included the advancement of 11 test pits to approximate depths up to 14.5 feet below existing site grades. Based on the information obtained from our subsurface exploration, the site is suitable for development of the proposed project. The following geotechnical considerations were identified: Soil Conditions:The soils encountered during field exploration generally included several feet of loose to medium dense surficial soils over dense to very dense silty sand with gravel glacial till. Localized areas were underlain by outwash deposits comprised of medium dense to dense sand with varying amounts of gravel. Groundwater: No groundwater seepage was encountered during our subsurface exploration. Foundations: Foundations for the proposed residences may be supported on conventional spread footings bearing on medium dense to dense native soil or structural fill. Slab-on-grade: Slab-on-grade floors and slabs for the proposed residences can be supported on medium dense to dense native soil or structural fill. Pavements: The following pavement sections are recommended: i► For access roadways areas: 3 inches of Hot Mix Asphalt (HMA) class%: inch PG 58H-22 over 2 inches of crushed surfacing top course (CSTC)over 6 inches of crushed surfacing base course (CSBC) For concrete pavement areas: 5 inches of concrete over 4 inches of CSTC ago - RILEYGROUP Geotechnical Engineering Report 1 May 14,2020 Olympic Ridge,Belfair,Washington RGI Project No.2020-007-1 1.0 Introduction This Geotechnical Engineering Report (GER) presents the results of the geotechnical engineering services provided for the Olympic Ridge in Belfair, Washington. The purpose of this evaluation is to assess subsurface conditions and provide geotechnical recommendations for the construction of a single family residential development with access roadways, associated utilities, and stormwater ponds. Our scope of services included field explorations, laboratory testing, engineering analyses, and preparation of this GER. The recommendations in the following sections of this GER are based upon our current understanding of the proposed site development as outlined below. If actual features vary or changes are made, RGI should review them in order to modify our recommendations as required. in addition, RGI requests to review the site grading plan, final design drawings and specifications when available to verify that our project understanding is correct and that our recommendations have been properly interpreted and incorporated into the project design and construction. 2.0 Project description The project site is located at State Highway 3 in Belfair, Washington. The approximate location of the site is shown on Figure 1. The site is currently unoccupied land, covered in dense vegetation and trees. RGI understands that a single family residential development with an access roadway, associated utilities, and stormwater ponds will be constructed on the site. At the time of preparing this GER, building plans were not available for our review. Based on our experience with similar construction, RGI anticipates that the proposed residences will be supported on perimeter walls with bearing loads of two to four kips per linear foot, and a series of columns with a maximum load up to 30 kips. Slab-on-grade floor loading of 250 pounds per square foot (psf) are expected. 3.0 Field Exploration and Laboratory Testing 3.1 FIELD EXPLORATION On April 9, 2020, RGI observed the excavation of 11 test pits.The approximate exploration locations are shown on Figure 2. Field logs of each exploration were prepared by the geotechnical engineeror geologist that continuously observed the excavation. These logs included visual classifications of the materials encountered during excavation as well as our interpretation of the subsurface conditions between samples. The test pits logs included in Appendix A represent an now L- RILEYGROUP Geotechnical Engineering Report 2 May 14,2020 Olympic Ridge,8elfoir, Washington RGI Project No 2020-007-1 interpretation of the field logs and include modifications based on laboratory observation and analysis of the samples. 3.2 WORATORY TESTING During the field exploration,a representative portion of each recovered sample was sealed in containers and transported to our laboratory for further visual and laboratory examination. Selected samples retrieved from the test pits were tested for moisture content and grain size analysis to aid in soil classification and provide input for the recommendations provided in this GER.The results and descriptions of the laboratory tests are enclosed in Appendix A. 4.0 Site Conditions 4.1 SURFACE The subject site consists of two irregular-shaped parcels of land (Mason County parcels 12328-21-000 and 12329-24-000) totaling approximately 61.26 acres in size. The site is bound to the north by undeveloped property, to the east by undeveloped forested land and a railroad right of way, to the south by undeveloped, forested land,and to the west by undeveloped property and State Highway 3. The railroad right of way extends diagonally through the northern portion of the property. Portions of each parcel located to the east of the railroad right of way are not included in the proposed development. The existing site is developed with a waterline that extends through the site from a water tower to the east of the property, with a pump station near the northeast property corner and the line extending west, then southwest through the northern portion of the property and then extending along the western property line in the southern portion of the property. An access road extends through the site along the waterline route, The remainder of the site is undeveloped forest. Site topography is comprised of an eastern bench area and a western slope area, with a total elevation change across the site of about 150 feet from a topographic high in the east- central portion of the property to a topographic low near the southwest property corner. The eastern bench area slopes generally west at gradients in the range of 5 to 15 percent. The western slope area is comprised of a generally west-facing hillside with slope gradients of generally 20 to 35 percent, with slopes along several drainages increasing to about 40 to 50 percent. Portions of the road cut along the western property line in the southern portion of the property have gradients of about 50 percent,as well as the railroad cuts off site along the eastern property line and extending through the northern portion of the property. A natural slope and a fill slope for the rail line are located in the southeast corner of the site, and descend at gradients of 40 to 50 percent.The site is vegetated with small-to large- 1 L- RIIEYGROUP Geotechnical Engineering Report 3 May 14,2020 Olympic Ridge,Belfair,Washington RGI Project No.2020-007-1 diameter trees, grass, mixed brush, ferns, moss, and localized blackberry brambles and scotch broom. 4.2 GEOLOGY Review of the Geologic Map of the 8elfair 7.5-minute Quadrangle, Mason, Kitsap, and Pierce Counties Washington, by Michael Polenz, etc. (2009) indicates that the soil through most of the site is mapped as Vashon till (Qgt), which is a compact mixture of clay, silt, sand, and gravel deposited at the base of the Vashon ice sheet. Areas along the western property line are mapped as Vashon advance outwash (Qga), which is stratified sand and gravel deposited by meltwater streams issuing from the advancing Vashon ice sheet. The northern tip of the site is mapped as Vashon glacial ice-contact deposits (Qgic) which is stratified sand and gravel and glacial till deposited alongside ice from the Vashon ice sheet. These descriptions are generally similar to the findings in our field explorations.The general location of the geologic units from the geologic map are shown on Figure 3.A geologic cross section is shown on Figure 4. 4.3 SOILs The soils encountered during field exploration generally included several feet of loose to medium dense surficial soils over dense to very dense silty sand with gravel glacial till. Localized areas were underlain by outwash deposits comprised of medium dense to dense sand with varying amounts of gravel. Reconnaissance of the railroad cut along the eastern property line showed glacial till exposed at the surface along nearly all of the property line, with the exception of sand and gravel exposed in the northern portion extending north from just south of the waterline crossing which is likely an ice-contact deposit. More detailed descriptions of the subsurface conditions encountered are presented in the test pits included in Appendix A. Sieve analysis was performed on three selected soil samples. Grain size distribution curves are included in Appendix A. 4.4 GROUNDWATER No groundwater seepage or surficial water was encountered during our exploration. It should be recognized that fluctuations of the groundwater table will occur due to seasonal variations in the amount of rainfall, runoff, and other factors not evident at the time the explorations were performed. In addition, perched water can develop within seams and layers contained in fill soils or higher permeability soils overlying less permeable soils following periods of heavy or prolonged precipitation. Therefore, groundwater levels during construction or at other times in the future may be higher or lower than the levels 11 1 L- RILEYGROUP Geotechnical Engineering Report 4 May 14,2020 Olympic Ridge,Belfair,Washington RGI Project No.2020-007-1 indicated on the logs. Groundwater level fluctuations should be considered when developing the design and construction plans for the project. 4.5 SEISMIC CONSIDERATIONS Based on the International Building Code (IBC), RGI recommends the follow seismic parameters for design. Table 1 2012/2015 IBC Parameter 2015 Value 2018 Value Site Soil Class' C2 Site Latitude 47.4559 Site Longitude -122.8154 Short Period Spectral Response Acceleration,Ss(g) 1.473 1,621 1-Second Period Spectral Response Acceleration, St (g) 0.584 0.574 Adjusted Short Period Spectral Response Acceleration, Seas(g) 1,473 1.945 Adjusted 1-Sec Period Spectral Response Acceleration,SM, (g) 0.759 0.818 Numeric seismic design value at 0.2 second;Sos(g) 0.982 1.297 Numeric seismic design value at 1.0 second;SMi(g) 0.506 0.546 1.Note:In general accordance with Chapter 20 of ASCE 7-10 and 7-16,the Site Class is based on the average characteristics of the upper loo feet of the subsurface profile. 2.Note:ASCE 7-10 and 7-16 require a site soil profile determination extending to a depth of 100 feet for seismic site classification.The current scope of our services does not include the required 100 foot soil profile determination.Test pits extended to a maximum depth of 15 feet,and this seismic site class definition considers that very dense soil continues below the maximum depth of the subsurface exploration. Additional exploration to deeper depths would be required to confirm the conditions below the current depth of exploration. Liquefaction is a phenomenon where there is a reduction or complete loss of soil strength due to an increase in water pressure induced by vibrations from a seismic event. Liquefaction mainly affects geologically recent deposits of fine-grained sands that are below the groundwater table. Soils of this nature derive their strength from intergranular friction.The generated water pressure or pore pressure essentially separates the soil grains and eliminates this intergranular friction, thus reducing or eliminating the soil's strength. RGI reviewed the results of the field and laboratory testing and assessed the potential for liquefaction of the site's soil during an earthquake. Since the site is underlain by glacial till and glacially consolidated deposits, and lacks an established shallow groundwater table, RGI considers that the possibility of liquefaction during an earthquake is minimal. 1 LM RILEYGROUP Geotechnical Engineering Report 5 May 14,2020 Olympic Ridge,Belfair,Washington RGI Project No.2020-007.1 4.6 GEOLOGIC HAZARD AREAS Regulated geologically hazardous areas include erosion, landslide, earthquake, or other geological hazards. Based on review of the Mason County Code, portions of the site meet the criteria of erosion hazard areas and geologically hazardous areas. 4.6.1 EROSION HAZARD AREAS Portions of the site are mapped as Alderwood gravelly sandy loam, 15 to 30 percent slopes, and meet the criteria for an erosion hazard area. Most of the slopes in the western portion of the site as well as the slopes in the southeast site corner are erosion hazards. An erosion and sedimentation control plan should be established during construction as described in Section 5.2.1 of this report. 4.6.2 GEOLOGICALLY HAZARDOUS AREAS Portions of the site meet the criteria of geologically hazardous areas due to slopes with gradients greater than 40 percent. This included localized areas along the drainages in the western portion of the site and southeast site corner,as well as road cuts along the western property line and railroad cuts in the eastern portion of the property. 4.6.3 SLOPE RECONNAISSANCE A slope reconnaissance was performed on April 9, 2020 to assess the stability of the site slopes.During the reconnaissance, no signs of recent slide activity were observed. No seeps or springs were observed. Trees with curved trunks were observed on steeper slopes that is indicative of surficial creep. The slopes are well vegetated and appear to be stable, however, shallow debris-flow failures are possible during heavy rainfall events. Cut slopes were lightly to moderately vegetated, and appear to be cut primarily into dense glacial till. Based on reviewing the Mason County GIS, no landslide activity is mapped within 500 feet of the site. Based on the density of the subsurface soils and inclination of the slopes, the slopes onsite are stable in their present condition and configuration. A quantitative slope stability was not completed for the site slopes as deeper explorations would be required to compile slope stability profiles, however based on our experience with similar soils and slope conditions, stable conditions of 1.5 for static and 1.1 for seismic conditions currently exist on the site slopes. 4.6.4 RECOMMENDATIONS Review of the proposed development plans indicate the geologically hazardous areas are generally to remain undeveloped (Tract"A",Tract "B",and Tract "F") with the exception of modification of the road cuts along the western property line near the proposed stormwater detention facility located on the west central portion of the site. The facility will be a cut into the dense glacial till soils. 1 LU RILEYGROUP Geotechnical Engineering Report 6 May 14,2020 Olympic Ridge,8elfair,Washington RGI Project No.2020-007-1 The preliminary grading plan shows fills on the top of the existing slopes on the north and west sides of the site. Typically, these areas are not geologic hazards areas but these feasibility of these fills both from a construction and slope stability standpoint will need to be further evaluated as the grading plans are finalized. A buffer of 10 feet should be maintained from the greater than 40 percent slopes located in the drainage areas on the northern and western slopes. No buffers are required from the cut on the railroad as this is a cut into the dense native soils. Setbacks in addition to the buffers should be determined as the grading plans are finalized. The 10-foot buffer areas are shown on Figure 3. 5.0 Discussion and Recommendations 5.1 GEOTECHNICAL CONSIDERATIONS Based on our study, the site is suitable for the proposed construction from a geotechnical standpoint.The site will be developed with a residential plat and storm water will be routed to a central detention pond. The site development is not expected to have an adverse impact to the site or surrounding side provided best management practices for erosion control and construction techniques are implemented during the development of the site. Foundations for the proposed residences can be supported on conventional spread footings bearing on competent native soil or structural fill. Slab-on-grade floors and pavements can be similarly supported. Detailed recommendations regarding the above issues and other geotechnical design considerations are provided in the following sections. These recommendations should be incorporated into the final design drawings and construction specifications. 5.2 EARTHWORK The earthwork is expected to include grading the site for lot and roadway grades, installing site utilities, construction of the access road, and excavating for stormwater facilities. 5.2.1 EROSION AND SEDIMENT CONTROL Potential sources or causes of erosion and sedimentation depend on construction methods, slope length and gradient, amount of soil exposed and/or disturbed, soil type, construction sequencing and weather.The impacts on erosion-prone areas can be reduced by implementing an erosion and sedimentation control plan. The plan should be designed in accordance with applicable city and/or county standards. RGI recommends the following erosion control Best Management Practices (BMPs): Y Scheduling site preparation and grading for the drier summer and early fall months and undertaking activities that expose soil during periods of little or no rainfall � 1 � RILEYGROUP Geotechnicol Engineering Report 7 May 14,2020 Olympic Ridge,Belfoir,Washington RGl Project No 1020-007-1 ➢ Retaining existing vegetation whenever feasible Y Establishing a quarry spall construction entrance ➢ Installing siltation control fencing or anchored straw or coir wattles on the downhill side of work areas ➢ Covering soil stockpiles with anchored plastic sheeting ➢ Revegetating or mulching exposed soils with a minimum 3-inch thickness of straw if surfaces will be left undisturbed for more than one day during wet weather or one week in dry weather ➢ Directing runoff away from exposed soils and slopes ➢ Minimizing the length and steepness of slopes with exposed soils and cover excavation surfaces with anchored plastic sheeting (Graded and disturbed slopes should be tracked in place with the equipment running perpendicular to the slope contours so that the track marks provide a texture to help resist erosion and channeling. Some sloughing and raveling of slopes with exposed or disturbed soil should be expected.) ➢ Decreasing runoff velocities with check dams, straw bales or coir wattles ➢ Confining sediment to the project site ➢ Inspecting and maintaining erosion and sediment control measures frequently(The contractor should be aware that inspection and maintenance of erosion control BMPs is critical toward their satisfactory performance. Repair and/or replacement of dysfunctional erosion control elements should be anticipated.) Permanent erosion protection should be provided by reestablishing vegetation using hydroseeding and/or landscape planting. Until the permanent erosion protection is established, site monitoring should be performed by qualified personnel to evaluate the effectiveness of the erosion control measures. Provisions for modifications to the erosion control system based on monitoring observations should be included in the erosion and sedimentation control plan. 5.2.2 STRIPPING Stripping efforts should include removal of pavements, vegetation, organic materials, and deleterious debris from areas slated for building, pavement, and utility construction. The test pits encountered 2-9 inches of topsoil and rootmass. Deeper areas of stripping may be required in forested or heavily vegetated areas of the site. Based on the preliminary grading plan,the site will be cleared and developed in two phases. Clearing is expected to consist of logging and stump removal using conventional means followed by stripping and stockpiling the native topsoil for reuse on the lots after final grades are reached. now LU RILEYGROUP Geotechnical Engineering Report 8 May 14,2020 Olympic Ridge,Belfoir,Washington RGI Project No-2020-007-1 5.2.3 EXCAVATIONS All temporary cut slopes associated with the site and utility excavations should be adequately inclined to prevent sloughing and collapse. The site soils consist of dense to very dense silty sand with some gravel, overlain by loose to medium dense sandy gravel. In some areas dense sands with some silt and the occasional cobble were encountered. Accordingly,for excavations more than 4 feet but less than 20 feet in depth, the temporary side slopes should be laid back with a minimum slope inclination of 1H:1V (Horizontal:Vertical). If there is insufficient room to complete the excavations in this manner,or excavations greater than 20 feet in depth are planned, using temporary shoring to support the excavations should be considered. For open cuts at the site, RGI recommends: ➢ No traffic, construction equipment, stockpiles or building supplies are allowed at the top of cut slopes within a distance of at least five feet from the top of the cut Exposed soil along the slope is protected from surface erosion using waterproof tarps and/or plastic sheeting Construction activities are scheduled so that the length of time the temporary cut is left open is minimized ➢ Surface water is diverted away from the excavation The general condition of slopes should be observed periodically by a geotechnical engineer to confirm adequate stability and erosion control measures In all cases, however, appropriate inclinations will depend on the actual soil and groundwater conditions encountered during earthwork. Ultimately, the site contractor must be responsible for maintaining safe excavation slopes that comply with applicable OSHA or WISHA guidelines. 5.2.4 SITE PREPARATION RGI anticipates that some areas of loose or soft soil will be exposed upon completion of stripping and grubbing. Proofrolling and subgrade verification should be considered an essential step in site preparation. After stripping, grubbing, and prior to placement of structural fill, RGI recommends proofrolling building and pavement subgrades and areas to receive structural fill. These areas should moisture conditioned and compacted to a firm and unyielding condition in order to achieve a minimum compaction level of 95 percent of the modified proctor maximum dry density as determined by the American Society of Testing and Materials D1557-09 Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Modified Effort (ASTM D1557). Proofrolling and adequate subgrade compaction can only be achieved when the soils are within approximately± 2 percent moisture content of the optimum moisture content.Soils which appear firm after stripping and grubbing may be proofrolled with a heavy compactor, 1 L- RILEYGROUP GeotechniCol Engineering Report 4 May 14,2020 Olympic Ridge,Belfair,Washington RGI Project No-2020-007-1 loaded double-axle dump truck,or other heavy equipment under the observation of an RGI representative.This observer will assess the subgrade conditions prior to filling. The need for or advisability of proofrolling due to soil moisture conditions should be determined at the time of construction. In wet areas it may be necessary to hand probe the exposed subgrades in lieu of proofrolling with mechanical equipment. If fill is placed in areas of the site where existing slopes are steeper than 5:1 (Horizontal:Vertical), the area should be benched to reduce the potential for slippage between existing slopes and fills. Benches should be wide enough to accommodate compaction and earth moving equipment, and to allow placement of horizontal lifts of fill. Subgrade soils that become disturbed due to elevated moisture conditions should be overexcavated to reveal firm, non-yielding, non-organic soils and backfilled with compacted structural fill. In order to maximize utilization of site soils as structural fill, RGI recommends that the earthwork portion of this project be completed during extended periods of warm and dry weather if possible. If earthwork is completed during the wet season (typically November through May) it will be necessary to take extra precautionary measures to protect subgrade soils. Wet season earthwork will require additional mitigative measures beyond that which would be expected during the drier summer and fall months. 5.2.5 STRUCTURAL FILL Once stripping, clearing and other preparing operations are complete, cuts and fills can be made to establish desired building grades. Prior to placing fill, RGI recommends proof- rolling as described above. RGI recommends fill below the foundation and floor slab,behind retaining walls, and below pavement and hardscape surfaces be placed in accordance with the following recommendations for structural fill.The structural fill should be placed after completion of site preparation procedures as described above. The suitability of excavated site soils and import soils for compacted structural fill use will depend on the gradation and moisture content of the soil when it is placed.As the amount of fines (that portion passing the U.S. No. 200 sieve) increases, soil becomes increasingly sensitive to small changes in moisture content and adequate compaction becomes more difficult or impossible to achieve. Soils containing more than about 5 percent fines cannot be consistently compacted to a dense, non-yielding condition when the moisture content is more than 2 percent above or below optimum. Optimum moisture content is that moisture that results in the greatest compacted dry density with a specified compactive effort. LM RILEYGROUP Geotechnical Engineering Report 10 May 14,2020 Olympic Ridge,Belfair,Washington RGI Project No.2020-007-1 Non-organic site soils are only considered suitable for structural fill provided that their moisture content is within about two percent of the optimum moisture level as determined by ASTM D1557. Excavated site soils may not be suitable for re-use as structural fill depending on the moisture content and weather conditions at the time of construction. If soils are stockpiled for future reuse and wet weather is anticipated,the stockpile should be protected with plastic sheeting that is securely anchored. Even during dry weather, moisture conditioning (such as, windrowing and drying) of site soils to be reused as structural fill may be required. Even during the summer, delays in grading can occur due to excessively high moisture conditions of the soils or due to precipitation. If wet weather occurs, the upper wetted portion of the site soils may need to be scarified and allowed to dry prior to further earthwork, or may need to be wasted from the site. The site soils are moisture sensitive and may require moisture conditioning prior to use as structural fill. If on-site soils are or become unusable, it may become necessary to import clean, granular soils to complete site work that meet the grading requirements listed in Table 2 to be used as structural fill. Table 2 Structural Fill Gradation U.S.Sieve Size Percent Passing 4 inches 100 No. 4 sieve 22 to 100 No. 200 sieve 0 to 5* *Based on minus 3/4 Inch fraction. Prior to use, an RGI representative should observe and test all materials imported to the site for use as structural fill.Structural fill materials should be placed in uniform loose layers not exceeding 12 inches and compacted as specified in Table 3.The soil's maximum density and optimum moisture should be determined by ASTM D1557. Placement and compaction of structural fill should be observed by RGI. A representative number of in-place density tests should be performed as the fill is being placed to confirm that the recommended level of compaction is achieved. now LU RILEYGROUP Geotechnicol Engineering Report 11 May 14,2020 Olympic Ridge,Bel/air,Washington RGI Project No.2020-007-] Table 3 Structural Fill Compaction ASTM D1557 Minimum Moisture Content Location Material Type Compaction Percentage Range Foundations On-site granular or approved 95 +2 -2 imported fill soils: Retaining Wall Backfill On-site granular or approved 92 +2 -2 imported fill soils: Slab-on-grade On-site granular or approved 95 +2 -2 imported fill soils: General Fill (non- On-site soils or approved structural areas) imported fill soils: 90 +3 -2 Pavement—Subgrade On-site granular or approved 95 +2 -2 and Base Course imported fill soils: 5.2.6 CUT AND FILL SLOPES All permanent cut and fill slopes should be graded with a finished inclination no greater than 2H:1V. Upon completion of construction, the slope face should be trackwalked, compacted and vegetated,or provided with other physical means to guard against erosion. All fill placed for slope construction should meet the structural fill requirements as described in Section 5.2.5. Final grades at the top of the slopes must promote surface drainage away from the slope crest. Water must not be allowed to flow in an uncontrolled fashion over the slope face. If it is necessary to direct surface runoff towards the slope, it should be controlled at the top of the slope, piped in a closed conduit installed on the slope face, and taken to an appropriate point of discharge beyond the toe of the slope. 5.2.7 WET WEATHER CONSTRUCTION CONSIDERATIONS RGI recommends that preparation for site grading and construction include procedures intended to drain ponded water, control surface water runoff, and to collect shallow subsurface seepage zones in excavations where encountered. It will not be possible to successfully compact the subgrade or utilize on-site soils as structural fill if accumulated water is not drained prior to grading or if drainage is not controlled during construction. Attempting to grade the site without adequate drainage control measures will reduce the amount of on-site soil effectively available for use, increase the amount of select import fill materials required,and ultimately increase the cost of the earthwork phases of the project. Free water should not be allowed to pond on the subgrade soils. RGI anticipates that the use of berms and shallow drainage ditches, with sumps and pumps in utility trenches, will be required for surface water control during wet weather and/or wet site conditions. 1 1 LU RILEYGROUP Geotechnico!Engineering Report 12 May 14,2020 Olympic Ridge,Selfoir,Washington RGI Project No.2020-007-1 5.3 FOUNDATIONS Following site preparation and grading, the proposed residences foundation can be supported on conventional spread footings bearing on competent native soil or structural fill. Loose, organic, or other unsuitable soils may be encountered in the proposed residences footprint. If unsuitable soils are encountered,they should be overexcavated and backfilled with structural fill. Perimeter foundations exposed to weather should be at a minimum depth of 18 inches below final exterior grades. Interior foundations can be constructed at any convenient depth below the floor slab. Finished grade is defined as the lowest adjacent grade within 5 feet of the foundation for perimeter (or exterior) footings and finished floor level for interior footings. Table 4 Foundation Design Design Parameter Value Allowable Bearing Capacity- Structural Fill 2,500 psf1 Dense native soils 5,000 psf Friction Coefficient 0.30 Passive pressure (equivalent fluid pressure) 250 pcf2 Minimum foundation dimensions Columns: 24 inches Walls: 16 inches 1.psf=pounds per square foot 2.pcf=pounds per cubic foot The allowable foundation bearing pressures apply to dead loads plus design live load conditions. For short-term loads, such as wind and seismic, a 1/3 increase in this allowable capacity may be used. At perimeter locations, RGI recommends not including the upper 12 inches of soil in the computation of passive pressures because they can be affected by weather or disturbed by future grading activity. The passive pressure value assumes the foundation will be constructed neat against competent soil or backfilled with structural fill as described in Section 5.2.5. The recommended base friction and passive resistance value includes a safety factor of about 1.5. With spread footing foundations designed in accordance with the recommendations in this section, maximum total and differential post-construction settlements of 1 inch and 1/2 inch, respectively, should be expected. 5.4 RETAINING WALLS If retaining walls are needed in the building area, RGI recommends cast-in-place concrete walls be used.The magnitude of earth pressure development on retaining walls will partly L- RILEYGROUR Geotechnicol Engineering Report 13 May 14,2020 Olympic Ridge,Belfair,Woshington RGl Project No.2020-007-1 depend on the quality of the wall backfill. RGI recommends placing and compacting wall backfill as structural fill. Wall drainage will be needed behind the wall face. A typical retaining wall drainage detail is shown in Figure 5. With wall backfill placed and compacted as recommended, and drainage properly installed, RGI recommends using the values in the following table for design. Table 5 Retaining Wall Design Design Parameter Value Allowable Bearing Capacity- Structural Fill 2,500 psf Dense native soils 5,000 psf Active Earth Pressure (unrestrained walls) 35 pcf At-rest Earth Pressure (restrained walls) 50 pcf For seismic design, an additional uniform load of 7 times the wall height (H) for unrestrained walls and 14H in psf for restrained walls should be applied to the wall surface. Friction at the base of foundations and passive earth pressure will provide resistance to these lateral loads.Values for these parameters are provided in Section 5.3. 5.5 SLAB-ON-GRADE CONSTRUCTION Once site preparation has been completed as described in Section 5.2, suitable support for slab-on-grade construction should be provided. RGI recommends that the concrete slab be placed on top of medium dense native soil or structural fill. Immediately below the floor slab, RGI recommends placing a four-inch thick capillary break layer of clean, free-draining sand or gravel that has less than five percent passing the U.S. No. 200 sieve. This material will reduce the potential for upward capillary movement of water through the underlying soil and subsequent wetting of the floor slab. Where moisture by vapor transmission is undesirable, an 8- to 10-millimeter thick plastic membrane should be placed on a 4-inch thick layer of clean gravel. For the anticipated floor slab loading, we estimate post-construction floor settlements of 1/4- to 1/2-inch. For thickness design of the slab subjected to point loading from storage racks and fork lift vehicle traffic, RGI recommends using a subgrade modulus (KS) of 150 pounds per square inch per inch of deflection. LM RILEYGROUP Geotechnica!Engineering Report 14 May 14,2010 Olympic Ridge,Belj"air,Washington RGi Project No.2020-007-1 5.6 DRAINAGE 5.6.1 SURFACE free and positive drainage away from the building Final exterior grades should promote ee a p g y g area. Water must not be allowed to pond or collect adjacent to foundations or within the immediate building area. For non-pavement locations, RGl recommends providing a minimum drainage gradient of 3 percent for a minimum distance of 10 feet from the building perimeter. In paved locations, a minimum gradient of 1 percent should be provided unless provisions are included for collection and disposal of surface water adjacent to the structure. S.6.2 SUBSURFACE RGI recommends installing perimeter foundation drains. A typical footing drain detail is shown on Figure 6. The foundation drains and roof downspouts should be tightlined separately to an approved discharge facility.Subsurface drains must be laid with a gradient sufficient to promote positive flow to a controlled point of approved discharge. 5.6.3 INFILTRATION The site is underlain by glacially consolidated lodgment till soils. Due to the very dense nature of these soils and silt content there is little to no infiltration potential in these soils. Lodgment till soils are considered a"restrictive layer"when evaluating infiltration potential in stormwater design manuals. Based on our field observations of lodgment till soils infiltration via conventional infiltration facilities (infiltration ponds, trenches, or galleries) are not feasible at the site. 5.6.4 STORMWATER DETENTION POND The stormwater detention pond is located as shown on Figures 3 and 4. Based on the explorations, we expect the pond bottom will be in the very dense till soils which will restrict to infiltration rate no near zero. If sandy soils are encountered in the pond area the pond may need to have with a till liner. 5.7 UTILITIES Utility pipes should be bedded and backfilled in accordance with American Public Works Association (APWA) specifications. For site utilities located within the right-of-ways, bedding and backfill should be completed in accordance with City of Belfair specifications. At a minimum, trench backfill should be placed and compacted as structural fill, as described in Section 5.2.5. Where utilities occur below unimproved areas, the degree of compaction can be reduced to a minimum of 90 percent of the soil's maximum density as determined by the referenced ASTM D1557. As noted, soils excavated on site may not be LM RILEYGROUP Geotechnical Engineering Report 15 May 14,2020 Olympic Ridge,Belfoir,Washington RGI Project No.2020-007-1 suitable for use as backf ill material. Imported structural fill meeting the gradation provided in Table 2 should be used for trench backfill. 5.8 PAVEMENTS Pavement subgrades should be prepared as described in Section 5.2 and as discussed below. Regardless of the relative compaction achieved, the subgrade must be firm and relatively unyielding before paving. The subgrade should be proof-rolled with heavy construction equipment to verify this condition. 5.8.1 FLEXIBLE PAVEMENTS With the pavement subgrade prepared as described above, RGI recommends the following pavement sections for parking and drive areas paved with flexible asphalt concrete surfacing. > For access drive areas: 3 inches of Hot Mix Asphalt (HMA) class %Z inch PG 58H-22 over 2 inches of crushed surfacing top course (CSTC)over 6 inches of crushed surfacing base course (CSBC) 5.8.2 CONCRETE PAVEMENTS With the pavement subgrade prepared as described above, RGI recommends the following pavement sections for parking and drive areas paved with concrete surfacing. For concrete pavement areas: 5 inches of concrete over 4 inches of CSTC The paving materials used should conform to the WSDOT specifications for HMA, concrete paving, and CSBC and CSTC (9-03.9(3) Crushed Surfacing). Long-term pavement performance will depend on surface drainage. A poorly-drained pavement section will be subject to premature failure as a result of surface water infiltrating into the subgrade soils and reducing their supporting capability. For optimum pavement performance, surface drainage gradients of no less than 2 percent are recommended. Also, some degree of longitudinal and transverse cracking of the pavement surface should be expected over time. Regular maintenance should be planned to seal cracks when they occur. 6.0 Additional Services RGI is available to provide further geotechnical consultation throughout the design phase of the project. RGI should review the final design and specifications in order to verify that earthwork and foundation recommendations have been properly interpreted and incorporated into project design and construction. RGI is also available to provide geotechnical engineering and construction monitoring services during construction. The integrity of the earthwork and construction depends on 1 1 LW RILEYGROUP Geotechnical Engineering Report 16 May 14,2020 Olympic Ridge,Belfoir,Washington RGI Project No.2020-007-1 proper site preparation and procedures. In addition, engineering decisions may arise in the field in the event that variations in subsurface conditions become apparent. Construction monitoring services are not part of this scope of work. If these services are desired, please let us know and we will prepare a cost proposal. 7.0 Limitations This GER is the property of RGI, E. E. Overton, and its designated agents. Within the limits of the scope and budget, this GER was prepared in accordance with generally accepted geotechnical engineering practices in the area at the time this GER was issued.This GER is intended for specific application to the Olympic Ridge project in Belfair, Washington, and for the exclusive use of E. E.Overton and its authorized representatives. No other warranty, expressed or implied, is made. Site safety, excavation support, and dewatering requirements are the responsibility of others. The scope of services for this project does not include either specifically or by implication any environmental or biological (for example, mold,fungi, bacteria) assessment of the site or identification or prevention of pollutants, hazardous materials or conditions. If the owner is concerned about the potential for such contamination or pollution, we can provide a proposal for these services. The analyses and recommendations presented in this GER are based upon data obtained from the explorations performed on site.Variations in soil conditions can occur, the nature and extent of which may not become evident until construction. If variations appear evident, RGI should be requested to reevaluate the recommendations in this GER prior to proceeding with construction. It is the client's responsibility to see that all parties to the project, including the designers, contractors, subcontractors, are made aware of this GER in its entirety. The use of information contained in this GER for bidding purposes should be done at the contractor's option and risk. 1 1 16- RILEVGROUP G (Y Qgic Qgic 1 Qaf % r�/eft/• �� : '; -a ,, � i9 _y -= 1; I a , . : C2a I. # I =Cross section Aa o d AI. n �■ = 10' Buffer from 40%or greater slopes: `, Qaf =Alluvial fan Qgt =Vashon till -41 it T, / — — Qgic =Vashon glacial ice-contact deposits Approximate Scale: 1"=300' Qga =Vashon advance outwash A =Site boundary 0 150 300 600 N Corporate Office Olympic Ridge Preliminary Plat Figure 3 17522 Bothell Way Northeast RGI Project Number: Date Drawn: -Bothell,Washington 98011 2020-007-1 Slopes and Geology 10/2020 Phone:425.415.0551 HILEYGROUP Fax:425.415.0311 Address:State Highway 3, Belfair, Washington 98528 Forest Practices Activity Map -Application # 'Z o G 1 1 8666 �o0 170 68 170876D 1706762 + I + + I. + a20 � I 21 F MCKnlnh[RdF-- 170 6 \ 1708740 \ X 49� X -- 29 17086 1708628, f 1108720 r ) 17081 i N/� f + ; + I CD 27 1170 6• _ ?08608 i 17 7QO 1708702 N- I ` ............ 33 �� \� 34 1707780 �- ! 1707782 Map Symbols Additional Information Legal Description Hwwtt Boundary S Landing r l§�T}y F S28 T23.ON R01.OW --- Road Constaxtlon Q Mats Ana / 8enwn Clumped ©� v ��tiLy is ® RhAZ/W.8ulfarc 1MRTSrGRTS 4 J L a 'x Rock Pit / Existing Structure $ s L� 'req— 1 Extreme care was used during the Compilation of this map to ensure ,,.., ,., its accuracy. However,due to changes in data and the need to 0 025 11R TURAL RE50URCC$ rely on outside information,the Department of Natural Resources cannot accept responsibility for errors or omissions, and therefore, there are no warranties that acoompany this material. Date:6/30/2020 Time:2:37:19 PM = NE NEWK IRK RD. AC,AQ ,�� CC c �Q w 2 w Al i t -j { 2OO I USGS, 2017, Belfair, Washington Approximate Scale: 1"=1000' 7.5 Minute Quadrangle 0 500 1000 2000 N Corporate Office Olympic Ridge Preliminary Plat Figure 1 17522 Bothell Way Northeast RGI Project Number: Date Drawn: Bothell,Washington 98011 Site Vicinity Map Phone:425.415.0551 2020-007-1 1 05/2020 RILEYGROUP Fax 425,415.0311 Address: State Highway 3, Belfair, Washington 98528 e l 10 -1 6 '< i i I / " ' TP-2 e f 1 / P- � r/ r r ` s � 1 -11 s � �. � • r 1 0 .DTP-6 r • r a • . l _ r _ i �N r , • I a . r I _� � r • I =Test pit by RGI, 04/09/20 Approximate Scale: 1"=300' A =Site boundary 0 150 300 600 N . , =Corporate Office Olympic Ridge Preliminary Plat Figure 2 11522 Bothell Way Northeast RGI Project Number, Date Drawn: ,-Bothell,Washington 98011 2020 007 1 Geotechnical Exploration Plan Phone:425.415.0551 OS/2020 RILUGROUP Fax:425.415.0311 Address: State Highway 3, Belfair, Washington 98528 400 400 opt 300 300 200 200 0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 =Vashon till =Vashon advance outwash Approximate Scale: 1"=150' 0 75 150 300 N -Corporate Office Olympic Ridge Preliminary Plat Figure 4 17522 Bothell Way Northeast RGI Project Number: Date Drawn: '-Bothell,Washington 98011 Cross Section A-A' Phone:425.415.0551 2020-007-1 1 0512020 RILEYGROUP Fax:425.415.0311 Address: State Highway 3, Belfair, Washington 98528 ' Qgic Qgic � �gs r /i y Y � a Qga y y Oft � ■ � r t Y e e ■ j r 1 1 ! 9 -- — ——--—— ■ ram— \ t ■ 1 -� r • r 1 , ' Qga s ! = I . � � r e ■ I e / r■ ` a 1 /.//. r I ----� =Cross section A-A' �. ■ � r ■ I = 10 Buffer from 40%or greater slopes ° x r r • ■ { = Alluvial fan FL. -., r Qgt =Vashon till — Qgic = Vashon glacial ice-contact deposits Qga = Vashon advance outwash Approximate Scale: 1"=300' A = Site boundary 0 150 300 600 N Corporate Office Olympic Ridge Preliminary Plat Figure 3 11111 Bothell Way Northeast RGI Project Number Date Drawn: -Bothell,Washington 98011 2020-007-1 Slopes and Geology 05/2020 Phone:425.415.0551 RILEYGROUP Fax:425.415.0311 Address: State Highway 3, Belfair, Washington 98528 12" Minimum Wide Free-Draining Gravel Slope to Drain • 12" min. .. .. , .. Filter Fabric Material • oa Excavated Slope " (See Report for .S Appropriate 0 o Incliniations) '$ Compacted Structural •"sa Backfill(Native or Import) 12"Over the Pipe P 4" Diameter PVC 3" Below the Pipe Perforated Pipe Not to Scale Corporate office Olympic Ridge Preliminary Plat Figure 5 • , -11511 Bothell Way Northeast RGI Project Number: Date Drawn: -Bothell,Washington 98011 2020 007-1 Retaining Wall Drainage Detail Phone:425.41S.0551 05�2020 RILEYGROUP Fax:425.415.0311 Address: State Highway 3, Belfair,Washington 98528 Building Slab A 10 \ • d.. =. ' Compacted \ ', �Structural'�, r � Backfill- •\ e Filter Fabric / / •' • d" \� 4" Perforated Pipe 3/4" Washed Rock or Pea Gravel Not to Scale . corporate office Olympic Ridge Preliminary Plat Figure 6 , - 17522 Bothell Way Northeast RGI Project Number: Date Drawn: -Bothell,Washington 98011 2020-007-1 Typical Footing Drain Detail Phone:425.415.0551 OS/2020 RILEYGROUP Fax:425.41S.0311 Address:State Highway 3, Belfair,Washington 98528 Geotechnicol Engineering Report May 14,2020 Olympic Ridge,Belfair,Washington RGI Project No.2020-007-1 APPENDIX A FIELD EXPLORATION AND LABORATORY TESTING On April 9, 2020, RGI performed field explorations using a trackhoe. We explored subsurface soil conditions at the site by observing the excavation of 11 test pits to a maximum depth of 14.5 feet below existing grade. The test pits locations are shown on Figure 2. The test pit locations were approximately determined by measurements from existing property lines and paved roads. A geologist from our office conducted the field exploration and classified the soil conditions encountered, maintained a log of each test exploration, obtained representative soil samples, and observed pertinent site features. All soil samples were visually classified in accordance with the Unified Soil Classification System (USCS). Representative soil samples obtained from the explorations were placed in closed containers and taken to our laboratory for further examination and testing.As a part of the laboratory testing program, the soil samples were classified in our in house laboratory based on visual observation,texture,plasticity,and the limited laboratory testing described below. Moisture Content Determinations Moisture content determinations were performed in accordance with ASTM D2216-10 Standard Test Methods for Laboratory Determination of Water (Moisture) Content of Soil and Rock by Mass (ASTM D2216)on representative samples obtained from the exploration in order to aid in identification and correlation of soil types.The moisture content of typical sample was measured and is reported on the test pit logs. Grain Size Analysis A grain size analysis indicates the range in diameter of soil particles included in a particular sample. Grain size analyses was determined using D6913-04(2009) Standard Test Methods for Particle-Size Distribution (Gradation) of Soils Using Sieve Analysis (ASTM D6913) on three of the samples. LU RILEYGROUP Project Name: Olympic Ridge Test Pit No.: TP-1 Project Number: 2020-007-1 , ,- Client: E.E. Overton RILEYGROUP Sheet 1 of 1 Date(s)Excavated: V912020 Logged By ELW Surface Conditions: Mixed Brush,Moss Excavation Method: Test Pit Bucket Size: NIA Total Depth of Excavation: 10.5 feet bgs Excavator Type: Tracked Excavator Excavating Contractor: Kelly's Excavating Approximate 320 Surface Elevation Groundwater Level Not Encountered Sampling Grab Compaction Method Bucket Method(s) Test Pit Backfill. Cuttings Location State Highway 3,Betfalr,Washington m _ w Z_ E B y m 6 F— Z T —J O m d co U L a to Ln n E E V ro w rn in c� MATERIAL DESCRIPTION REMARKS AND OTHER TESTS 320 0 TPSL �,- 6"topsoil sM Reddish brown silty SAND with some gravel,loose,moist 8%moisture SP Gray gravelly SAND with trace silt,medium dense,moist • (Advance Outwash) .f {I •t�i « 5%moisture,2%fines S 315 5-1 1�: Becomes dense,occasional cobble ..• 3%moisture « •:Ii .S SP•sM ; Gray SAND with some silt and gravel,dense,moist •.f. (Advance Outwash) 310 10 1 7%moisture Test Pit terminated at 10.5' 3D5 15 The Riley Group,Inc. 17522 Bothell Way NE.Bothell,WA 98011 Project Name: Olympic Ridge Test Pit No.: TP-2 Project Number: 2020-007-1 , ,- Sheet 1 of 1 Client: E.E. Overton RILEYGROUP Dalets)Excavated. Q912020 Logged By ELW Surface Conditions: Grass Excavation Method: Test Pit Bucket Size: NIA Total Depth of Excavation. 6.5 feet bgs Approximate Excavator Type: Tracked Excavator Excavating Contract Surface Kelly's Excavating 326 ace Elevation Groundwater Level: Not Encountered Sampling Grab Compaction Method Bucket Method(s) Test Pit Backflll: Cuttings Location State Highway 3,Belfair,Washington a� E E $ c 1 Z VJ u is L — a rn t > a E E U m w p in to j [7 MATERIAL DESCRIPTION REMARKS AND OTHER TESTS 376 0 TPSL 9"topsoil sm Reddish brown silty SAND with some gravel,loose,moist 8%moisture SP-sm Gray SAND with some sill and gravel,medium dense,moist r •i 5%moisture s"^ Gray silty gravelly SAND,very dense,moist(Glacial Till) 321 5 8%moisture. 19%fines Test Pit terminated at 6.5' 316 10 311 15 The Riley Group,Inc. 17522 Bothell Way NE,Bothell,WA 98011 Project Name: Olympic Ridge Test Pit No.: TP-3 Project Number: 2020-007-1 , L- Sheet 1 of 1 Client: E.E. Overton RIlEYGRDUP Date(s)Excavated: 4/9/2020 Logged By ELW Surface Conditions. Mixed Brush Excavation Method: Test Pit Bucket Size: N/A Total Depth of Excavation: 5 feet bgs Excavator Type: Tracked Excavator Excavating Contractor: Kelly's Excavating Approximate Surface Surface Elevation Groundwater Lever Not Encountered Sampling Grab Compaction Method Bucket Method(s) Test Pit Backfill: Cuttings Location State Highway 3,Belfair,Washington m ^ c E gE S Wy c y H Z > > a E E U nm w 0 U) i In n j 0 MATERIAL DESCRIPTION REMARKS AND OTHER TESTS 312 0 TPSL 6"topsoil SM Reddish brown silty gravelly SAND,loose,moist 7%moisture Becomes tan,medium dense sM Gray silty SAND with some gravel,very dense,moist (Glacial Till) 7%moisture 307 s Test Pit terminated at 5' 302 10 297 15 The Riley Group.Inc 17522 Bothell Way NE,Bothell,WA 98011 Project Name: Olympic Ridge Test Pit No.: TP-4 Project Number: 2020-007-1 , ,- Sheet 1 of 1 Client: E.E. Overton RILEYGROUP Date(s)Excavated: 4/9/2020 Logged By ELW Surface Conditions: Mixed Brush Excavation Method: Test Pit Bucket Size: N/A Total Depth of Excavation 4.5 feet bgs Excavator Type: Tracked Excavator Excavating Contractor. Kelly's Excavating Approximate 322 Surface Elevation Groundwater Level: Not Encountered SamplingMethod(s) Grab Compaction Method Bucket Test Pit Backfill: Cuttings Location State Highway 3,Belfalr,Washington a O N H Z U Q G7 16 L n E E U M w o� rn V) MATERIAL DESCRIPTION REMARKS AND OTHER TESTS 322 0 TPSL "' = 6"topsoil SM Reddish brown silty SAND with some gravel,loose to medium dense, moist 11%moisture SM Gray silty SAND with some gravel,dense to very dense, moist(Glacial Till) 7%moisture Becomes very dense Test Pit terminated at 4.5' 317 5 312 10 30I 15 The Riroy Group,Inc. 17522 Bothell Way NE,Bothell,WA 98011 1 Project Name: Olympic Ridge Test Pit No.: TP-5 Project Number: 2020-007-1 1 L V Sheet 1 of 1 Client: E.E. Overton RILEYGROUP Date(s)Excavated: 4/9/2020 Logged By ELW Surface Conditions: Mixed Brush Excavation Method: Test Pit Bucket Size: N/A Total Depth of Excavation: 5.5 feet bgs Excavator Type: Tacked Excavator Excavating Contractor: Kelly's Excavating Approximate 324 Surface Elevation Groundwater Level: Not Encountered Sampling Grab Compaction Method Bucket Method(s) Test Pit Backfill: Cuf ings Location State Highway 3,Betfair,Washington d w c E a c 1— Z > u o m to t — is to E CL aa) m m rn ° w MATERIAL DESCRIPTION REMARKS AND OTHER TESTS 32d 0 TPSL 6"topsoil sM Reddish brown silty SAND with some gravel,loose to medium dense,moist 10%moisture sm Gray silty SAND with some gravel,dense,moist(Glacial Till) 8%moisture 319 5-1 Becomes very dense 7%moisture Test Pit terminated at 5.5' 314 10 309 15 The Riley Group,Inc 17522 Bothell Way NE,Bothell,WA 98011 Project Name: Olympic Ridge Test Pit No.: TP-6 Project Number: 2020-007-1 Sheet 1 of 1 Client: E.E.Overton RILEYGROUP Date(s)Excavated. 4 12020 Logged By ELW Surface Conditions: Mixed Brush Excavation Method: Test Pit Bucket Size: N/A Total Depth of Excavation: 6 feet bgs Excavator T Approximate Type Tracked Excavator Excavating Contractor. Kelly's Excavating Surface Elevation 327 Groundwater Level. Not Encountered Sampling Grab Compaction Method Bucket Methods) Test Pit Backfill: Cuttings Location State Highway 3,Belfair,Washington w m c F- Z s 1 T tv 16 t — a to t E E Un w p in U) j 0 MATERIAL DESCRIPTION REMARKS AND OTHER TESTS 327 D TPSL w" 6"topsoil sM Reddish brown silty SAND with some gravel,loose to medium dense,moist 11%moisture Becomes medium dense sM Gray silty SAND with some gravel,dense,moist(Glacial Till) 322 5 7%moisture Test Pit terminated at 6' 317 10 31Z 15 The Riley Group,Inc. 17522 Bothell Way NE.Bothell.WA 98011 Project Name: Olympic Ridge Test Pit No.: TP-7 Project Number: 2020-007-1 Sheet 1 of 1 Client: E.E. Overton RILEYGROUP Date(s)Excavated: 4/9/2020 Logged By EI-W Surface Conditions: Mixed Brush Excavation Method: Test Pit Bucket Size: NIA Total Depth of Excavation 14.5 feet bgs Excavator Type: Tracked Excavator Excavating Contractor: Kelly's Excavating Approximate 318 Surface Elevation Groundwater Level: Not Encountered Sampling Grab Compaction Method Bucket Method(s) Test Pit Backfill Cuttings Location State Highway 3,Belfair,Washington d _ m E $ z >. —J O G1 N N _U L a VJ L > G U Ili `° `0O Lo 0 D U MATERIAL DESCRIPTION REMARKS AND OTHER TESTS 318 0 TPSL 6"topsoil sM Reddish brown silty SAND with some gravel,dense,moist (Glacial Till) 9%moisture 6%moisture 313 s Becomes very dense 5%moisture 30e 10 4%moisture Test Pit terminated at 14.5' 303 15 i The Riley Group,Inc 17522 Bothell Way NE,Bothell,WA 98011 Project Name: Olympic Ridge Test Pit No.: TP-9 Project Number: 2020-007-1 Client: E.E. Overton RILEYGROUP Sheet 1 of 1 Date(s)Excavated: 4t9/2020 Logged By ELW Surface Conditions: Moss Excavation Method: Test Pit Bucket Size NIA Total Depth of Excavation: 5 feet bgs Excavator Type: Tracked Excavator Excavating Contractor. Kelly's Excavating Approximate 328 Surface Elevation Groundwater Level Not Encountered Sampling Grab Compaction Method Bucket Method(s) Test Pit Backfill Cuttings Location State Highway 3,Belfair,Washington m e S t— z > L a to a > n E E V 2 R to p W U) j 0 MATERIAL DESCRIPTION REMARKS AND OTHER TESTS 32e 0 TPSL w 6"topsoil GP a D Reddish brown sandy GRAVEL,loose to medium dense, 'ot, moist d. 0 4%moisture SOD sM Gray silty SAND with some gravel,dense,moist(Glacial Till) Becomes very dense 8%moisture 323 5- Test Pit terminated at 5' 318 10 313 15 The Riley Group.Inc 17522 Bothell Way NE,Bothell,WA 98011 Project Name: Olympic Ridge 10 Test Pit No.: TP-10 Project Number: 2020-007-1 , lk- Client: E.E. Overton RILEYGROUP Sheet 1 of 1 Date(s)Excavated: 4/9/2020 Logged By ELW Surface Conditions Scotch Broom,Grass Excavation Method: Test Pit Bucket Size: NIA Total Depth of Excavation: 1.5 feet bgs Excavator Type: Tracked Excavator Excavating Contractor. Kelly's Excavating Approximate 300 Surface Elevation Groundwater Level: Not Encountered Sampling Grab Compaction Method Bucket Method(s) Test Pit Backfill: Cuttings Location State Highway 3,Belfair,Washington d _ E $ r Z i. J O y (U U) U 16 L d to L n E E U m w p in to j MATERIAL DESCRIPTION REMARKS AND OTHER TESTS 300 0 TPSL 2"LOPSOII sM Gray silty SAND with some gravel,dense,moist(Glacial Till) 6%moisture Test Pit terminated at 1 5' 295 5 2B0 1G 285 15 The Riley Group,Inc 17522 Bothell Way NE,Bothell,WA 98011 Project Name: Olympic Ridge Test Pit No.: TP-11 Project Number: 2020-007-1 , ,' Client: E.E. Overton RIIEYGROUP Sheet 1 of 1 Date(s)Excavated: 4t9l2020 Logged By ELW Surface Conditions. Scotch Broom,Grass Excavation Method: Test Pit Bucket Size. NIA Total Depth of Excavation: 5.5 feet bgs Excavator Type: Tracked Excavator Excavating Contractor: Kelly's Excavating Approximate 270 Surface Elevation Groundwater Level: Not Encountered Sampling Grab Compaction Method Bucket Method(s) Test Pit Backrill: Cuttings Location State Highway 3,Belfair,Washington ro _ E $ y :5 y H Z T O y y to U_ m n E E U m w 0 i) in � 0 MATERIAL DESCRIPTION REMARKS AND OTHER TESTS 270 0 TPSL 4"topsoil sM Reddish brown silty SAND with some gravel,loose to medium dense,moist Becomes medium dense SPSM • Gray gravelly SAND with some silt,medium dense,moist 2e,5 5 (Advance Outwash} 5%moisture Test Pit terminated at 5.5' 26c 10 255 15 The Rdey Group,Inc. 17522 Bothell Way NE,Bothell,WA 98011 Project Name: Olympic Ridge Test Pit No.: TP-8 Project Number: 2020-007-1 Client: E.E. Overton RIL'ROUP Sheet 1 of 1 Dates)Excavated: Existing(Unknown) Logged By ELW Surface Conditions: Moss Excavation Method: Test Pit Bucket Size: Total Depth of Excavation: Excavator T Excavating Contractor. Approximate Type: g Co tracto 329 Surface Elevation Groundwater Level: Not Encountered Sampling Compaction Method Methods) Test Pit Backfill: Location State Highway 3,Bell Washington g g c N H Z a m L — a to n > a E E U d 411 w p `n in j 0 MATERIAL DESCRIPTION REMARKS AND OTHER TESTS 329 0 TPSL 1"' 4"topsoil sM Reddish brown silty SAND with some gravel,loose to medium dense,moist 13%moisture sM Gray silty SAND with some gravel,dense,moist(Glacial Till) Existing lest pit extended to 3' 324 5 319 10 314 15 The Riley Group.Inc. 17522 Bothell Wey NE,Bothell,WA 98011 Project Name: Olympic Ridge Project Number: 2020-007-1 � 1 � Key to Logs Client: E.E. Overton R'iEE,R Sheet 1 of 1 m ° E 8 S C I. Z I. J O m y !n U ip t a N L > a E E U n d m w o in in c� MATERIAL DESCRIPTION REMARKS AND OTHER TESTS Li 2 3 L§J COLUMN DESCRIPTIONS 1MElevation(feet):Elevation(MSL,feet). 8 USCS Symbol: USCS symbol of the subsurface material. 2 Depth(feet):Depth in feet below the ground surface. 6 Graphic Log:Graphic depiction of the subsurface material 3 Sample Type:Type of soil sample collected at the depth interval encountered. shown. O MATERIAL DESCRIPTION.Description of material encountered. ® Sample Number:Sample identification number. May include consistency,moisture,color,and other descriptive text. ® REMARKS AND OTHER TESTS:Comments and observations regarding drilling or sampling made by driller or field personnel. FIELD AND LABORATORY TEST ABBREVIATIONS CHEM:Chemical tests to assess corrosivity PI Plasticity index,percent COMP:Compacbon test SA:Sieve analysis(percent passing No.200 Sieve) CONS One-dimensional consolidation test UC: Unconfined compressive strength test,Qu,in ksf LL:Liquid Limit,percent WA:Wash sieve(percent passing No.200 Sieve) MATERIAL GRAPHIC SYMBOLS ••. o4 017!Poorly graded GRAVEL(GP) Ltt Poorly graded SAND(SP) An� •.11 Silty SAND(SM) ; Poorly graded SAND with Silt(SP-SM) *r Topsoil TYPICAL SAMPLER GRAPHIC SYMBOLS OTHER GRAPHIC SYMBOLS Auger sampler CME Sampler Pitcher Sample ---y Water level(at time of drilling,ATD) � Water level(after waiting) Bulk Sample Grab Sample spoon(S unlined split p p Spoon(SPT) Minor change in material properties within a 4 stratum m3-inch-OD California w/ ' 2.5-Inch-OD Modified Shelby Tube(Thin-walled, _ - Inferred/gradational contact between strata brass rings California w/brass liners fixed head) -'- Queried contact between strata GENERAL NOTES 1 Soil classifications are based on the Unified Soil Classification System.Descriptions and stratum lines are interpretive,and actual lithologic changes may be gradual.Field descriptions may have been modified to reflect results of lab tests. 2:Descriptions on these logs apply only at the specific boring locations and at the time the borings were advanced They are not warranted to be representative of subsurface conditions at other locations or times. The Riley Group,Inc 17522 Bothell Way NE.Bothell,WA 98011 THE RILEY GROUP,INC. PHONE: (425)415-0551 17522 Bothell Way NE FAX: (425)415-0311 Bothell,WA 98011 GRAIN SIZE ANALYSIS F- ASTM D421, D422, D1140, D2487, D6913 PROJECT TITLE Olympic Ridge SAMPLE ID/TYPE TP-1 S-2 PROJECT NO. 2020-007 SAMPLE DEPTH 3' TECH/TEST DATE Pt 4/13/2020 DATE RECEIVED 4/10/2020 WATER CONTENT(Delivered Moisture) Total Weight Of Sample Used For Sieve Corrected For Hygroscopic Moisture Wt Wet Soil&Tare(gm) (wl) 863.3 Weight Of Sample(gm) 825.6 Wt Dry Soil&Tare(gm) (w2) 825.6 Tare Weight (gm) 160 Weight of Tare(gm) (w3) 16.0 (W6) Total Dry Weight(gm) 809.6 Weight of Water(gm) (w4=wl-w2) 37.7 SIEVE ANALYSIS Weight of Dry Soil(gm) (w5=w2-w3) 809 6 Cumulative Moisture Content(%) (w4/w5)'100 5 Wt Ret Wt-Tare) (%Retained) %PASS +T re (Iwt ret/w61'100i 100-%ret %COBBLES 0.0 12.0" 16.0 0.00 0.00 100.00 cobbles •C GRAVEL 14.1 3.0" 16.0 0.00 0.00 100.00 coarse gravel %F GRAVEL 27.7 2.5" coarse gravel 9'e C SAND 9.7 2.0" coarse gravel %M SAND 15.9 1.5" 16.0 0.00 0.00 100.00 coarse gravel %F SAND 30.7 1.0" coarse gravel •FINES 1.9 0.75" 129.9 113.90 14.07 85.93 fine gravel •TOTAL 100.0 0.50" fine gravel 0.375" 263.2 247.20 30.53 69.47 fine gravel D10(mm) 0.17 #4 354.4 338.40 41.80 58.20 coarse sand D30(mm) 0.37 #10 433.3 417.30 51.54 48.46 medium sand D60(mm) 4-8 #20 medium sand Cu 28.2 #40 562.0 546.00 67.44 32.56 fine sand Cc 0.2 #60 fine sand #100 772.0 756.00 93.38 6.62 fine sand #200 810.5 794.50 98.13 1.87 fines PAN 825.6 809.60 100.00 0.00 silt/clay 12" 3" 2" 1".75" .376" 04 *t0 020 M40 060 0100 0200 100 % 90 80 P 70 A 60 - S 50 40 S 30 - - 1 20 N 10 G 0 1000 100 10 1 0.1 0.01 0.001 Grain size in millimeters DESCRIPTION Gravelly SANI)with trace silt USCS Prepared For: Reviewed By. KW EE Overton ,- RILEYGROUP r-- THE RILEY GROUP,INC. PHONE: (425)415-0551 17522 Bothell Way NE FAX: (425)415-0311 Bothell,WA 98011 GRAIN SIZE ANALYSIS ASTM D421, D422, D1140, D2487, D6913 PROJECT TITLE Olympic Ridga SAMPLE ID/TYPE TP-2 S-3 PROJECT NO. 2020-007 SAMPLE DEPTH 6' TECH/TEST DATE r 1 4/23/2020 DATE RECEIVED 4/10/2020 WATER CONTENT(Delivered Moisture) Total We4tht Of Sample Used For Sieve Corrected For Hverosc i Moisture Wt Wet Soil&Tare(gm) (WI) 925.7 Weight Of Sample(gm) 861.9 Wt Dry Soil&Tare(gm) (w2) 861.9 Tare Weight (gm) 16.3 Weight of Tare(gm) (w3) 16.3 (W6) Total Dry Weight(gm) 845.6 Weight of Water(gm) (w4=wl-w2) 63.8 SIEVE ANALYSIS Weight of Dry Soil(gm) (w5=w2-w3)1 845.6 Cumulative Moisture Content(90) (w4/w5)'100 8 Wt Ret Wt-Tare (%Retained) %,PASS +Tare 1 We ret/w6)•1001 100%ret •COBBLES 0.0 12.0" 0.00 0.00 10000 cobbles %C GRAVEL 10.S 3.0" i+ 0.00 0.00 100.00 coarse gravel %F GRAVEL 21.9 2.5" coarse gravel %C SAND 8.8 2.0" coarse gravel •M SAND 16.2 1.5" 16.3 0.00 0.00 100.00 coarse gravel %F SAND 23.3 1.0" coarse gravel %FINES 19.3 0.75" 104.9 88.60 10.48 89.52 fine gravel %TOTAL 100.0 0.50" fine gravel 0.37S" 195.3 179.00 21.17 78.83 fine gravel D10(mm) #4 290.1 273.80 32.38 67.62 coarse sand D30(mm) #10 364.7 348.40 41.20 58.80 medium sand D60(mm) #20 medium sand Cu #40 502.1 485.80 57.45 42.55 fine sand Cc #60 fine sand #1001 650.8 634.50 1 75.04 1 24.96 fine sand #2001 699.1 682.80 1 80.75 1 19.25 fines PAN 861.9 845.60 1 100.DO 0.00 silt/clay 12- 3' 2' V 75- 375- $4 010 020 a0 060 8100 0200 90 S00 90 80 P 70 A 60 S 50 40 S 30 - 1 20 N 10 G 0 1000 100 10 1 0.1 0.01 0.001 Grain size in millimeters DESCRIPTION Silty Gravelly SAND USCS SM Prepared For Reviewed By: KW EE Overton ,_ RILEYGROUP THE RILEY GROUP,INC. PHONE: (425)415-0551 17522 Bothell Way NE FAX: (425)415-0311 Bothell,WA 98011 GRAIN SIZE ANALYSIS ASTM D421, D422, D1140, D2487, D6913 PROJECT TITLE Olympic Ride SAMPLE ID/TYPE i 3 PROJECT NO. 2020-007 SAMPLE DEPTH TECH/TEST DATE PL 4/13/2020 DATE RECEIVED 4/1o/202c; WATER CONTENT(Delivered Moisturel Total Weight Of Sample Used For Sieve Corrected For Hvgroscopic Moisture Wt Wet Soil&Tare(gm) (W1) 703.2 Weight Of Sample(gm) Wt Dry Soil&Tare(gm) (w2) 656.5 Tare Weight (gm) Weight of Tare(gm) (w3) 16.1 (W6) Total Dry Weight(gm) 640.4 Weight of Water(gm) (w4=wl-w2) 46.7 SIEVE ANALYSIS Weight of Dry Soil(gm) (w5=w2-w3) 640.4 Cumulative Moisture Content(%) (w4/w5)'100 7 Wt Ret Wt-Tare (%Retained) %PASS +T re ilwt(et/w6l'100) 100-%ret %COBBLES 0.0 12.0" 161 0.00 0.00 100.00 cobbles %C GRAVEL 8.0 3.0" 16.1 0.00 0.00 100.00 coarse gravel •F GRAVEL 20.5 2.5" coarse gravel %C SAND 19.6 2.0" coarse gravel •M SAND 23.2 1.5" 16.1 0.00 0.00 100.00 coarse gravel %F SAND 20.2 1.0" coarse gravel •FINES 8.5 0.75" 67 5 51.40 8.03 91.97 fine gravel •TOTAL 100.0 0.50" fine gravel 0.375" 136.1 120.00 18.74 81.26 fine gravel D10(mm) 0A #4 199.0 182-90 28.56 71.44 coarse sand D30(mm) 044 #10 324.2 308.10 48.11 51.89 medium sand D60(mm) 2.8 #20 medium sand Cu 28.0 #40 472.5 456.40 71.27 28.73 fine sand Cc 0.7 #60 fine sand #100 576.0 559.90 87.43 12.57 fine sand #21301 602.1 1 586.00 1 91.51 1 8.49 fines PANI 656.5 1 64040 1 100.00 1 0.00 silt/clay 12" 3" 7 1".75" .375` ra 810 820 $40 060 0100 0200 % 100 90 80 P 70 A 60 S 50 40 S 30 I 20 N 10 G 0 1000 100 10 1 0.1 0.01 0.001 Grain size in millimeters DESCRIPTION Poorly graded SAND with some silt,some gravel USCS SP-SM Prepared For Reviewed By: KW EE Overton ,- RILEYGROUP