The URL can be used to link to this page

Home My WebLink AboutGeotechnical reportGEOTECHNICAL REPORT Olympic Discovery Trail - Larry Scott Trail to Anderson Lake State Park Prepared for: Otak, Inc Project No. 210421  December 21, 2023 FINAL e a r t h w a t e r+ GEOTECHNICAL REPORT Olympic Discovery Trail - Larry Scott Trail to Anderson Lake State Park Prepared for: Otak, Inc Project No. 210421  December 21, 2023 FINAL Aspect Consulting Erik O. Andersen, PE Principal Geotechnical Engineer erik.andersen@aspectconsulting.com Samantha Muchongwe, EIT Staff Geotechnical Engineer samantha.muchongwe@aspectconsulting.com V:\210421 Olympic Discovery Trail\Deliverables\Geotechnical Report\Final\Olympic Discovery Trail_Report_2023.12.21.docx 12/21/2023 ear t h +wate r Aspect Consulting 103 E Holly Street Suite 320 Bellingham, WA 98225 360.746.2855 www.aspectconsulting.com ASPECT CONSULTING PROJECT NO. 210421  DECEMBER 21, 2023 FINAL i Contents 1 Introduction ................................................................................................. 1 1.1 Project Description ....................................................................................... 1 1.2 Scope of Work .............................................................................................. 1 2 Site Conditions ............................................................................................ 2 2.1 Surface Conditions ....................................................................................... 2 2.2 Geology ........................................................................................................ 2 2.3 Subsurface Conditions ................................................................................. 3 2.3.1 Subsurface Explorations by Aspect ....................................................... 3 2.3.2 General Stratigraphy .............................................................................. 3 2.3.3 Groundwater .......................................................................................... 4 2.3.4 Laboratory Testing ................................................................................. 4 2.4 Geologic Hazards ......................................................................................... 4 2.4.1 Earthquake Engineering ........................................................................ 4 2.4.2 Seismicity and Surficial Ground Rupture ............................................... 6 2.4.3 Liquefaction ............................................................................................ 6 2.4.4 Landslide Hazards ................................................................................. 6 3 Geotechnical Engineering Conclusions .................................................... 7 3.1 Retaining Walls ............................................................................................ 7 3.1.1 Lateral Earth Pressures ......................................................................... 7 3.2 Stormwater Infiltration .................................................................................. 7 3.3 Pavement Design Considerations ................................................................ 9 4 Earthwork Considerations ........................................................................ 10 4.1 Temporary Erosion Control ........................................................................ 10 4.2 Structural Fill .............................................................................................. 10 4.2.1 Reuse of Site Soils as Structural Fill .................................................... 10 4.2.2 Imported Structural Fill ......................................................................... 11 4.2.3 Backfill in Mapped Wetland Areas ....................................................... 12 4.3 Compaction Requirements ......................................................................... 12 4.4 Temporary Excavations and Slopes .......................................................... 13 4.4.1 Permanent Slopes ............................................................................... 13 4.5 Wet Weather Construction ......................................................................... 14 4.6 Construction Dewatering ............................................................................ 14 5 Recommendations for Continuing Geotechnical Services .................... 15 5.1 Additional Design and Consultation Services ............................................ 15 5.2 Additional Construction Services ............................................................... 15 ASPECT CONSULTING ii FINAL PROJECT NO. 210421  DECEMBER 21, 2023 6 References ................................................................................................. 16 7 Limitations .................................................................................................. 17 List of Figures 1 Site Location Map 2 Site and Exploration Map List of Appendices A Subsurface Exploration Logs B Geotechnical Laboratory Analysis Results C Pilot Infiltration Testing D Report Limitations and Guidelines for Use ASPECT CONSULTING PROJECT NO. 210421  DECEMBER 21, 2023 FINAL 1 1 Introduction Aspect Consulting (Aspect) prepared this report for Otak Inc, (Otak) on behalf of Jefferson County (County) to support the construction of a segment of the Olympic Discovery Trail (Project). The Project segment runs from the Larry Scott Trail to Anderson Lake State Park (Site, Figure 1) in Jefferson County, Washington. This report summarizes explorations and geotechnical data collected to date and presents our geotechnical engineering conclusions and recommendations based on our analysis of the data and current design concepts. The information and recommendations presented in this report are intended to assist the design team select Project options for stormwater management, cut or fill retaining walls, site earthwork, and surfacing along the trail. 1.1 Project Description We understand the Project will consist of the design and construction of an approximate 3-mile-long multi-use trail beginning at the Larry Scott Trailhead and running parallel (west-east direction) to South Discovery Road and Four Corners Road for the first half-mile. For the following two miles, the trail runs parallel to the existing access road (north-south direction) and the last half-mile of the trail runs perpendicular to the access road (east-west direction) before ending at Andersen Lake State Park. The ADA- accessible trail will be constructed primarily at existing grade; switchbacks and retaining walls will be used where the ground slopes and permanent cut slopes are infeasible. 1.2 Scope of Work Our scope of work includes conducting subsurface explorations, laboratory testing, and an assessment of the feasibility of stormwater infiltration based on soil laboratory testing. This scope provides the baseline data for geotechnical recommendations for the Project. This report includes: • Site and Project descriptions; • Distribution and characteristics of subsurface soils; • Description of the field work completed; • Gravity block walls; • Stormwater infiltration feasibility; • Earthwork and grading, cut, and fill recommendations; and • Considerations for re-use of on-site material as structural fill. Our work was completed in accordance with the proposal dated October 1, 2021. This draft report is provided to summarize our key findings and conclusions in support of the conceptual engineering design by Otak. As more details are determined and provided to us by Otak, this draft report can be expanded to be mutually supportive of the final design concepts. Our subsurface investigation logs and laboratory testing results are attached as Appendices A and B, respectively. ASPECT CONSULTING 2 FINAL PROJECT NO. 210421  DECEMBER 21, 2023 2 Site Conditions This section presents the Site conditions, including surface conditions, critical area mapping, geologic setting, and subsurface conditions encountered in our reconnaissance. This information provides context for the discussion of types and distribution of geologic soil units and a basis for our geotechnical engineering recommendations. 2.1 Surface Conditions The Project alignment runs through a rural area between the Jefferson County Airport and Anderson Lake, in Jefferson County. The 3-mile trail begins at the Larry Scott Trailhead and runs parallel to South Discovery Road and Four Corners Road before turning south and running parallel to an existing access road owned by the County and then turns east to end at Anderson Lake State Park (Figure 1). The Site is located entirely within parcels owned by Jefferson County (Parcel IDs #000000230; #001333014; #0013330037; #001333038; #901042005; #901092003). The proposed trail varies in elevation (EL)1 between EL 130 at the lowest trail point and EL 405 at the highest trail point. The shoulders of South Discovery Road, Four Corners Road, and the County-owned access road are vegetated with a combination of grass, brush, and mature trees. There are several locations along the proposed Project trail alignment where existing ground slopes by greater than 40 percent. At these locations, the ground slopes into creek banks or steep hillsides which are moderately vegetated with trees, ferns, bushes, and other groundcovers. Substantial cuts along the tops of the steep slopes, and substantial fills along the bases of the steep slopes, are planned to meet ADA grade/slope requirements (Otak, 2023). The goal is to place material derived from cuts in the high areas as structural fill in the lower areas to the extent possible. 2.2 Geology The Site is located in the central portion of the Puget Lowland. The Puget Lowland is a complex tectonic environment and an area of tectonic subsidence flanked by two mountain ranges—the Cascades to the east and the Olympics to the west. The sediments within the Puget Lowland result from repeated cycles of glacial and nonglacial deposition and erosion. During nonglacial cycles, the area was dominated by lowland forests and broad river valleys. During glacial cycles, ice sheets up to 3,000 feet thick occupied the Puget Lowland and surrounding areas, carved out the deep marine waterways and river valleys, and sculpted the uplands. Deposits from these glacial and nonglacial cycles are present in the subsurface of the Project vicinity. The available geologic mapping indicates the Site is underlain by Pleistocene age glacial continental drift and glacial till (Schasse and Slaughter, 2005). The geology of the Site generally consists of Vashon Stade lodgment till, Vashon Stade advance outwash, 1 All elevations in this report are relative to the North American Vertical Datum of 1988 (NAVD88). ASPECT CONSULTING PROJECT NO. 210421  DECEMBER 21, 2023 FINAL 3 Vashon Stade recessional outwash, and Everson Interstade glaciomarine outwash deposits. Soil units are described in more detail in Section 2.3.2. 2.3 Subsurface Conditions Subsurface conditions at the Site were inferred from Aspect’s completed field investigation, our review of applicable geologic literature, local geologic experience, and geotechnical laboratory and in situ testing. 2.3.1 Subsurface Explorations by Aspect In August 2023, Aspect planned and executed subsurface explorations at the Site. These included: • Eleven excavated test pits, ATP-01 through ATP-11, advanced between August 28 and August 30, 2023, to depths between 4 and 16.5 feet below ground surface (bgs) along the proposed Project trail alignment. • One hang auger, AHA-01, advanced on August 30, 2023, to 2 feet bgs along the proposed trail alignment. The locations of the explorations are shown on Figure 2. Exploration logs are included as Appendix A. The geotechnical laboratory testing results were incorporated into the subsurface exploration logs in Appendix A. Further description of the laboratory test methods and results are presented in Appendix B. 2.3.2 General Stratigraphy Based on the completed subsurface explorations, we grouped the Site soils into four units: topsoil, Everson Interstade glaciomarine outwash, Pleistocene glacial continental drift and Pleistocene continental glacial till. The composition and distribution of these units are summarized below. For more detailed information regarding the composition and distribution of these units, please refer to the exploration logs provided in Appendix A. 2.3.2.1 Topsoil Topsoil refers to a unit that contains a high percentage of organics, generally found at the ground surface and containing grass, mulch, and roots. We encountered up to 1.5 feet of topsoil in our explorations. 2.3.2.2 Everson Interstade Glaciomarine Outwash Everson Interstade glaciomarine outwash deposits were observed in explorations ATP-01 through ATP-04 beneath the topsoil at depths ranging from 0.25 ft bgs to up to 15 ft bgs. The glacimarine outwash deposits typically consisted of coarse-grained, medium to dense, dry to moist, brown, sand (SM) with varying amounts of silt, gravel and cobbles, and fine-grained, stiff to hard, slightly moist, gray silt (ML). The glaciomarine outwash deposits exhibit moderate shear strength characteristics, moderate compressibility, moderate permeability, and moderate moisture sensitivity. ASPECT CONSULTING 4 FINAL PROJECT NO. 210421  DECEMBER 21, 2023 2.3.2.3 Pleistocene Glacial Continental Drift Pleistocene glacial continental drift deposits were observed beneath the topsoil at varying depths between 0.3 and 14 feet bgs in ATP-05, ATP-08, and ATP-09. The glacial continental drift deposits generally consisted of medium dense to dense, gray-brown, slightly moist to moist sand with varying amounts of silt, gravel, cobbles and boulders (SM, SP-SM); and dense, brown, moist clayey gravel with varying amounts of sand and cobbles (GP-GM, GP-GC). The continental drift deposits exhibit moderate shear strength characteristics, moderate compressibility, moderate to high permeability, and low to moderate moisture sensitivity. 2.3.2.4 Pleistocene Continental Glacial Till Pleistocene continental glacial till was observed beneath the continental drift or topsoil at varying depths between 0.5 and 16.5 feet bgs in AHA-01, ATP-06, ATP-07 and ATP-09 through ATP-11. The glacial till generally consisted of dense to very dense, moist, gray and brown, silty sand with varying amounts of gravel and cobbles (SM); dense to very dense, gray-brown, moist, gravel with varying amounts of silt, sand and cobbles (GM, GP-GM); and very stiff to hard, moist, gray, silt (ML). The glacial till exhibits high shear strength characteristics, low to moderate compressibility, very low permeability, and moderate to high moisture sensitivity. 2.3.3 Groundwater Groundwater seepage was encountered in ATP-09 at a depth of 6 feet bgs but was not encountered in any other exploration. Groundwater levels will fluctuate seasonally with precipitation, as well as with changes in Site and near-Site usage. 2.3.4 Laboratory Testing Selected soil samples were submitted for geotechnical laboratory testing of index properties. Laboratory testing including natural moisture content, Atterberg Limits, and grain-size distribution. Further description of the soil samples submitted, test methods, and results are presented in Appendix B. 2.4 Geologic Hazards Aspect considered geologic hazards relevant to the Site and Project. This section provides context for County requirements related to Project development given typical earthquake engineering considerations at the Site. 2.4.1 Earthquake Engineering The Site is located within the Puget Lowland physiographic province, an area of active seismicity that is subject to earthquakes on shallow crustal faults and deeper subduction zone earthquakes. The Site area lies about 29 miles north of the Seattle fault zone, which consists of shallow crustal tectonic structures that are considered active (evidence for movement within the Holocene [since about 15,000 years ago]) and is believed to be capable of producing earthquakes of magnitude 7.3 or greater. The recurrence interval of earthquakes on this fault zone is believed to be on the order of 1,000 years or more. The most recent large earthquake on the Seattle fault occurred about 1,100 years ago (Pratt et ASPECT CONSULTING PROJECT NO. 210421  DECEMBER 21, 2023 FINAL 5 al., 2015). There are also several other shallow crustal faults in the region capable of producing earthquakes and strong ground shaking. The Site area also lies within the zone of strong ground shaking from earthquakes associated with the Cascadia Subduction Zone (CSZ). Subduction zone earthquakes occur due to rupture between the subducting oceanic plate and the overlying continental plate. The CSZ can produce earthquakes up to magnitude 9.3 and the recurrence interval is thought to be on the order of about 500 years. A recent study estimates the most recent subduction zone earthquake occurred around 1700 (Atwater et al., 2015). Deep intraslab earthquakes, which occur from tensional rupture of the sinking oceanic plate, are also associated with the CSZ. An example of this type of seismicity is the 2001 Nisqually earthquake. Deep intraslab earthquakes typically are magnitude 7.5 or less and occur approximately every 10 to 30 years. The following sections present descriptions of seismic design considerations for the Project. 2.4.1.1 Ground Response The American Association of State Highway and Transportation Officials (AASHTO) seismic design is based on an event with a return period of 1,000 years. The U.S. Geological Survey (USGS) has an online tool for obtaining key design parameters for the AASHTO event using the probabilistic ground motion studies and maps for Washington. Seismic design for cut and fill walls located south of Station (STA) 135+00 should be completed with the specific ground motion parameters listed in Table 1 below. Table 1. Seismic Design Parameters Design Parameter Recommended Value Site Class C Peak Ground Acceleration (PGA) 0.393g(1) Short Period Spectral Acceleration (Ss) 0.872g 1-Second Period Spectral Acceleration (S1) 0.314g Site Coefficient (FPGA) 1.007 Site Coefficient (Fa) 1.051 Site Coefficient (Fv) 1.486 Design Peak Ground Acceleration (PGAm) 0.396 g Design Short Period Spectral Acceleration (SDS) 0.916 g Design 1-Second Period Spectral Acceleration (SD1) 0.466 g Notes: 1. g = gravitational force 2. Based on the latitude and longitude of the Site: 48.0495°N, 122.8206°W. ASPECT CONSULTING 6 FINAL PROJECT NO. 210421  DECEMBER 21, 2023 2.4.2 Seismicity and Surficial Ground Rupture The Site is in a seismically active area approximately 29 miles north of the Seattle fault zone (Gower et al., 1985), approximately 6.7 miles southeast of the Southern Whidbey Island fault zone, and approximately 1.3 miles north from the Hood Canal fault zone. It is also within the zone of potentially very strong shaking from the CSZ. Due to the suspected long recurrence interval and the proximity of the Site to the mapped fault traces, the potential for surficial ground rupture at the Site is considered low during the expected life of the Project. 2.4.3 Liquefaction Liquefaction occurs when loose, saturated, and relatively cohesionless soil deposits temporarily lose strength as a result of earthquake shaking. Potential effects of soil liquefaction include temporary loss of bearing capacity and lateral soil resistance, liquefaction-induced settlement, flow failure of end- or side-slopes, and lateral spreading—any of which could result in structural damage. Primary factors controlling the development of liquefaction include intensity and duration of strong ground motion, characteristics of subsurface soil, in situ stress conditions, and the depth to groundwater. The Washington Geologic Portal (DNR, 2023) maps the Site as having a low to very low liquefaction susceptibility. Therefore, we conclude that liquefaction is not a design consideration for the Project. 2.4.4 Landslide Hazards Landslides may be triggered by natural causes, such as precipitation, freeze-thaw cycles, or a seismic event, or be man-made (e.g., broken water pipes). Three types of landslides are common on steep slopes in the Puget Sound: topples, deep-seated rotational slides, and shallow flows (Varnes, 1978). Jefferson County Land Records GIS portal maps (County, 2023) a slight landslide hazard between STA 100+00 and STA 129+00 along and/or in close vicinity to the proposed trail path. During our Site visit, we did not observe evidence of historical, recent, or incipient landslide activity, and the stratigraphy of the Site soils is not prone to landslide activity in the context of the Site and Project. We also did not observe evidence of ongoing erosion, scour, or prominent groundwater seepage along the slopes. Given these observations, it is our opinion that landslide hazard at the Site is low, and we do not consider landslide hazards to be a significant hazard for the Project. ASPECT CONSULTING PROJECT NO. 210421  DECEMBER 21, 2023 FINAL 7 3 Geotechnical Engineering Conclusions This section discusses geotechnical engineering analyses in support of cut and fill retaining walls, Project design considerations and recommendations for infiltration feasibility and stormwater management, and related geotechnical matters to inform the 90 percent design submittal (Otak, 2023). Additional engineering analyses and evaluations may be required to support the final design of the Project. Key geotechnical considerations are summarized below and discussed in detail in subsequent sections. 3.1 Retaining Walls We understand that the Project might require cut retaining walls with exposed/retained heights under 4 feet. Cut retaining walls shorter than 4 feet can be constructed without engineering design. If the Project changes such that cut or fill walls that are greater than 4 feet are needed, local and global wall stability should be evaluated. Once wall-specific plans and profiles have been developed, Aspect will review and provide more detailed design and construction recommendations. 3.1.1 Lateral Earth Pressures For low cut gravity block walls, the retaining walls should be sufficiently strong to support an active earth pressure (expressed as an equivalent fluid density) of 35 pounds per cubic foot (pcf). Where walls are supporting the trail, a uniform horizontal rectangular surcharge pressure of 65 pounds per square foot (psf) should be added to this earth pressure load. Aspect will review with Otak once wall plans profiles and locations have been determined. 3.1.1.1 Lateral Load Resistance Lateral loads will be resisted through passive soil resistance against the foundation elements and frictional resistance along the base of the foundations. We assume the retaining walls that will be constructed at the base of open cuts will be backfilled with structural fill. For these structural backfill conditions and the granular foundation soils, an allowable passive earth pressure of 300 pcf and an allowable base friction coefficient of 0.35 can be used to calculate resistance to lateral loads. These allowable values each include a factor of safety of 1.5. 3.1.1.2 Backfilling The lateral earth pressures and friction parameters presented above assume the retaining wall is backfilled with structural fill. Structural backfill for the cut and fill retaining walls should consist of imported granular material meeting the requirements for Gravel Backfill for Walls, Washington State Department of Transportation Standard Specification 9-03.12(2) (WSDOT, 2024), or other granular material approved by Aspect. Structural fill placement and compaction should be in accordance with Section 5.3. 3.2 Stormwater Infiltration To assess the feasibility of stormwater infiltration along the proposed Project alignment, Aspect performed one pilot infiltration test (APIT-03) at approximate STA 156+00 in August 2023. The infiltration testing was conducted at a depth of 6 feet bgs and within ASPECT CONSULTING 8 FINAL PROJECT NO. 210421  DECEMBER 21, 2023 the coarse-grained glaciomarine outwash deposits. Based upon the results of our infiltration testing, the Site is feasible for infiltration within the coarse-grained glaciomarine outwash deposits where the infiltration trenches are anticipated. A summary of the PIT results is below in Table 2 below. A detailed description of the PITs is provided in Appendix C. Table 2. Design Infiltration Rates Pilot Infiltration Test ID Bottom of PIT Elevation Infiltration Depth (feet bgs.) Design Infiltration Rate (inches/hour) APIT-03 / Approx STA 156+00 135 6 0.3 Based on our explorations (Figure 2), most of the Site is underlain by mixed conditions: coarse-grained glaciomarine outwash, fine-grained glaciomarine, glacial till, and glacial continental drift deposits. The fine-grained glaciomarine outwash and glacial till deposits are relatively impermeable and unsuitable for infiltration. The coarse-grained glaciomarine and glacial continental drift deposits are moderately permeable and potentially suitable infiltration receptors. Our explorations encountered glaciomarine outwash and glacial continental drift deposits along the northern and approximate 1.5-mile portion of the Site, and glacial till deposits along the extended 1.5-mile segment of the southern portion of the Site. Infiltration feasibility along the trail is described in detail below. • The southern portion of the Site (STA 0+00 to STA 130+00) is generally underlain by relatively impermeable glacial till near the proposed trail elevation. Along this section of trail, infiltration is infeasible. We understand a combination of vegetated dispersion systems, quarry spall dispersion pads, and swales will be implemented as stormwater management methods (Otak, 2023). Stormwater management could also be accomplished using Low Impact Development (LID) methods combined with conventional methods, including catch basins and storm drainpipes that discharge into an appropriate system. LID methods, such as small rain gardens, and permeable pavements, are feasible provided the systems incorporate underdrains and/or overflow redundancy to account for the low permeability and low infiltration capacity of the Site soils. • The central portion of the Site (STA 130+00 to STA 145+00) is mostly underlain by moderately permeable glacial continental drift deposits near the proposed trail elevation. Along this section of the trail, infiltration is feasible, and we understand vegetated dispersion will be implemented as a stormwater management method. • The northern portion of the Site (STA 145+ to STA 180+00) is mostly underlain by coarse-grained glaciomarine outwash deposits, with the exception of an isolated section between approximately STA 145+00 and STA 160+00 where the coarse grained glaciomarine outwash deposits are overlain by up to 5 feet of impermeable fine-grained glaciomarine outwash deposits. Along this portion of the trail, infiltration is feasible within the coarse-grained glaciomarine outwash ASPECT CONSULTING PROJECT NO. 210421  DECEMBER 21, 2023 FINAL 9 deposits, and we understand the proposed infiltration trenches and bioretention trenches will be extended to a final depth within the coarse-grained glaciomarine outwash deposits (Otak, 2023). Utilizing the results of our day-long pilot infiltration test at ATP-03 (STA 156+00), considering geologic origin, and evaluation of grain size distributions, we consider the computed long-term design infiltration rate of 0.3 inches per hour, to be appropriate for design purposes, from project STA 130+00 to 180+00. 3.3 Pavement Design Considerations We understand the new trail will be surfaced with hot mix asphalt (HMA). We recommend a pavement section consisting of 3 inches of HMA over 6 inches crushed surfacing base or top course (CSBC or CSTC) as specified in Section 9-03.9(3) of the Standard Specifications (WSDOT, 2024). For new pavements constructed at or near existing grade, subgrade preparation should include removal of any organics and deleterious debris. Where soft, weak, peat-rich, or otherwise unsuitable subgrade is exposed during trail preparation, these materials should be removed and replaced with gravel borrow. An Aspect representative, or other County-designated qualified geo-inspector, should evaluate the extent and depth of these removals and replacements. ASPECT CONSULTING 10 FINAL PROJECT NO. 210421  DECEMBER 21, 2023 4 Earthwork Considerations Based on the explorations performed across the Site and our understanding of the Project, it is our opinion that the Contractor should be able to complete earthwork and excavations with standard construction equipment. The soils encountered at the Site coarse-grained glaciomarine outwash, coarse-grained continental drift and coarse-grained glacial till—are suitable for reuse as backfill material provided the materials are excavated during the dry season and are screened to ensure they are relatively free of organics, boulders and other deleterious debris. We recommend that earthwork activities be specified in accordance with WSDOT Standard Specifications (WSDOT, 2024). Appropriate erosion control measures should be in accordance with Section 8-01.3 Erosion Control and Water Pollution Control, Construction Requirements. 4.1 Temporary Erosion Control To prevent Site erosion during construction, appropriate temporary erosion and sedimentation control (TESC) measures should be used in accordance with our recommendations and local best management practices (BMPs). Specific TESC measures may include appropriately placed silt fencing, straw wattles, rock check dams, and plastic covering of soil stockpiles. 4.2 Structural Fill Soil placed beneath the HMA pavement at fill locations, above the trail subgrade at cut locations, around foundations, walls, or utilities, is considered structural fill. Structural fill should be placed over subgrades that have been prepared in conformance with the recommendations of this report. Source material should be derived from both imported sources and onsite native material deemed suitable for reuse as structural fill. We anticipate structural fill will be required primarily where over-excavation of existing nonengineered fill or soils above the proposed pedestrian walkway grade is required. 4.2.1 Reuse of Site Soils as Structural Fill This Project has been designed with a goal of balanced cuts and fills, meaning that surplus soil derived as cuts from high areas would be reused as fill in low areas. From a geotechnical standpoint, this will be feasible, provided the site work is done during the dry late summer and early fall months, and that the earthwork contractor follows general standards of practice. • The continental glacial till deposits that will be excavated from high ground areas contain a significant amount of fines (silt and clay particles). As such, this material is extremely moisture sensitive. Excavating or placing this material during the wet season and/or rainy weather conditions must be avoided. • The continental drift deposits at the site contain a significant amount of cobbles and occasional boulders. This material is suitable for use as fill if the large cobbles and boulders are screened prior to reuse as structural fill. ASPECT CONSULTING PROJECT NO. 210421  DECEMBER 21, 2023 FINAL 11 • The glaciomarine outwash deposits encountered at the Site are subdivided into fine-grained and coarse-grained outwash deposits. The fine-grained outwash deposits encountered at the Site contain a large amount of fines and are unsuitable for reuse as structural fill while the coarse-grained outwash deposits are suitable for reuse as structural fill. The contract documents should require the earthwork contractor to selectively screen and segregate the “good” fill material for re-use. Material to be reused should be screened to be free of organics/logs/stumps, boulders, peat, etc. The unsuitable materials should be exported from the Site or spread out along the corridor outside of the prism of structural trail fill. During placement, suitably processed on-site material should be at or near optimum moisture content, and it should be placed in 12-inch horizontal lifts and compacted with a vibratory drum roller to a dense and unyielding condition. An Aspect representative or County-designated qualified geo-inspector should be on site to inspect and approve this activity. 4.2.2 Imported Structural Fill While the Project has a goal of balanced cuts and fills, there will still be a need for imported structural fill. Table 4 below provides recommendations for imported structural fill materials and compaction. Table 4. Imported Structural Fill Material and Compaction Recommendations Application Specification Lift Thickness1 and Compaction2 Below Pavement WSDOT 9-03.9(3) – Crushed Surfacing 6 inches 95 percent Behind Walls WSDOT 9-03.12(2) – Gravel Backfill for Walls 8 inches 90 percent Utility Pipe Zone Bedding WSDOT 9-03.12(3) – Gravel Backfill for Pipe Zone Bedding 6 inches 95 percent Utility Pipe Zone Backfill3 WSDOT 9-03.12(3) – Gravel Backfill for Pipe Zone Bedding or WSDOT 7-08.3(3) – Pipe Zone Backfill 6 inches 95 percent Trench Backfill4 WSDOT 9-03.15 – Native Material for Trench Backfill or WSDOT 9-03.19 – Bank Run Gravel for Trench Backfill 8 inches 95 percent Unsuitable Material Replacement WSDOT 9-03.14(1) – gravel borrow 6 inches 95 percent Notes: 1. Maximum uncompacted thickness 2. Maximum dry density, as determined by ASTM D1557 (ASTM, 2018) 3. Varies per pipe material. Refer to WSDOT Standard Plan B-55.20-02 (WSDOT, 2024). 4. For trench backfill in roadway prisms: WSDOT 9-03.19, otherwise use WSDOT 9-03.19. The moisture content of structural fill should be controlled to within 2 to 3 percent of the optimum moisture. Optimum moisture is the moisture content corresponding to the maximum modified proctor dry density. ASPECT CONSULTING 12 FINAL PROJECT NO. 210421  DECEMBER 21, 2023 4.2.3 Backfill in Mapped Wetland Areas The 90 percent plans map wetlands in several areas along the proposed trail alignment (Otak, 2023). Aspect did not complete exploratory test pits or hand borings in these areas. It is reasonable to anticipate soft, wet, fine-grained and/or organic-rich conditions in/near active wetlands. Where soft/wet/weak fine-grained or organic-rich soil is encountered during trail subgrade preparation, we recommend sub-excavation to an average depth of 2 feet below subgrade elevation, and replacement with structural fill as recommended in Sections 4.2.1 and 4.2.2 above. Prior to replacing the sub-excavation with structural backfill, and depending on conditions at the minus-2-foot-level, it may also be appropriate to place a geotextile separation fabric, such as is specified in Section 9-33.2(1) of the WSDOT Standard Specifications. Aspect or another County-designated geo-inspector should make these determinations on a case-by-case basis. All of the unsuitable sub-excavated soils should be exported from the Site, or spread out in adjacent non-structural areas. 4.3 Compaction Requirements Structural fill should be at or near optimum moisture content at the time of placement and should be compacted to a percentage of the maximum dry density (MDD) as determined by test method ASTM International (ASTM) D1557, in accordance with the following recommendations: • Structural fill beneath foundations and hardscapes should be compacted to at least 95 percent of the MDD. • In nonstructural areas, fill should be placed and compacted to a moderately firm/dense condition. • Retaining wall backfill compaction within 5 feet of any wall should be limited to 90 percent of the MDD to avoid damage to the structure. Compaction within 5 feet of a wall should be achieved using small hand-operated equipment in conjunction with thinner soil lifts to achieve the required compaction. The procedure to achieve the specified minimum relative compaction depends on the size and type of compacting equipment, the number of passes, thickness of the layer being compacted, and certain soil properties. When the size of the excavation restricts the use of heavy equipment, smaller equipment can be used, but the soil must be placed in thin enough lifts to achieve the required compaction. A sufficient number of in-place density tests should be performed as the fill is placed to verify the required relative compaction is being achieved. The frequency of the in-place density testing shall be determined during construction and in test sections along the proposed trail. Generally, loosely compacted soils are a result of poor construction technique or improper moisture content. Soils with a high percentage of silt or clay are particularly susceptible to becoming too wet, and coarse-grained materials easily become too dry, for proper compaction. Silty or clayey soils with a moisture content too high for adequate compaction should be dried as necessary, or moisture conditioned by mixing with drier materials, or other methods. ASPECT CONSULTING PROJECT NO. 210421  DECEMBER 21, 2023 FINAL 13 When the first fill is placed in a given area, and/or any time the fill material changes, the area should be considered a test section. The test section should be used to establish fill placement and compaction procedures required to achieve proper compaction. Aspect or qualified materials inspection personnel should observe placement and compaction of the test section to assist in establishing an appropriate compaction procedure. Once a placement and compaction procedure is established, the Contractor’s operations should be monitored, and periodic density tests performed to verify that proper compaction is being achieved. 4.4 Temporary Excavations and Slopes Temporary excavations may be required where excavation to the bearing stratum is needed or where existing nonengineered fill should be over-excavated and replaced with structural fill. Maintenance of safe working conditions, including temporary excavation stability, is the responsibility of the Contractor. All temporary cuts in excess of 4 feet in height that are not protected by trench boxes or otherwise shored should be sloped in accordance with Part N of the Washington Administrative Code (WAC) 296-155 (WAC, 2020) as shown in the table below. Table 5. Temporary Excavation Cut Slope Recommendations Soil Slope Conditions OSHA Soil Classification Maximum Temporary Slope Maximum Height (ft) Existing Nonengineered Fill C 2H:1V 20 Cut Slope C 1.5H:1V 20 Notes: OSHA = Occupational Safety and Health Administration; H:V = Horizontal:Vertical The estimated maximum cut slope inclinations are provided for planning purposes only and are applicable to excavations without groundwater seepage or runoff, and assume dry to moist conditions. Flatter slopes will likely be necessary in areas where groundwater seepage exists, or where construction equipment surcharges are placed in close proximity with the crest of the excavation. With time and the presence of seepage and/or precipitation, the stability of temporary unsupported cut slopes can be significantly reduced. Therefore, all temporary slopes should be protected from erosion by installing a surface water diversion ditch or berm at the top of the slope. In addition, the Contractor should monitor the stability of the temporary cut slopes and adjust the construction schedule and slope inclination accordingly. Vibrations created by traffic and construction equipment may cause caving and raveling of the temporary slopes. In such an event, lateral support for the temporary slopes should be provided by the Contractor to prevent loss of ground support. 4.4.1 Permanent Slopes In our opinion, permanent cut slopes could be designed as steep as 1.5H:1V (horizontal:vertical) within the glacially consolidated upland soils and permanent fill slopes should be designed to be no steeper than 2H:1V along the Project corridor. We also recommend that cut and fill slopes be protected from surficial erosion with ASPECT CONSULTING 14 FINAL PROJECT NO. 210421  DECEMBER 21, 2023 hydroseeding. Permanent seeding may include native plants and grasses (applied by hydroseed with tackifier) with a temporary biodegradable erosion control blanket to cover the hydroseed and provide temporary protection until the grasses grow through the blanket. Where possible, the native topsoil should be retained and incorporated into the slopes prior to seeding Ecology’s SMMWW recommends permanent seeding and erosion control blankets be designed and installed in accordance with its BMPs C120 and C122, respectively (Ecology, 2019). 4.5 Wet Weather Construction The soils encountered across the Site are moderately moisture sensitive and may be difficult to handle, prepare, or compact with construction equipment during periods of wet weather. Earthwork is typically most economical when performed under dry weather conditions. If earthwork is to be performed or fill is to be placed in wet weather or under wet conditions, the following recommendations should be incorporated into the contract specifications: • Earthwork should be performed in small areas to minimize exposure to wet weather. Excavation or the removal of unsuitable soils should be followed promptly by the placement and compaction of clean structural fill. The size and type of construction equipment used may need to be limited to prevent soil disturbance. • Materials used as structural fill should consist of clean, granular soil containing less than 7 percent fines. The fines should be non-plastic. • The ground surface within the construction area should be sealed by a smooth drum vibratory roller (or equivalent) and under no circumstances should be left uncompacted and exposed to moisture. Soils which become too wet for compaction should be removed and replaced with clean granular materials. • Excavation and placement of structural fill should be observed by an Aspect representative, or other County-designated qualified geo-inspector, to verify that all unsuitable materials are removed, and suitable compaction is achieved. • Local BMPs for erosion protection should be strictly followed. 4.6 Construction Dewatering Groundwater was not encountered in the Site explorations; however, minor seepage and surficial runoff may be encountered at shallow depths. The Contractor should be prepared to adequately dewater foundation subgrade and excavations. We anticipate that strategically placed sumps and pumps will sufficiently control water inflow. Sumps are often constructed by placing a short section of perforated corrugated steel pipe (or surplus 8- to 12-inch-diameter well screen) in a small hole excavated below the subgrade elevation/excavation. The annular space around the pipe is backfilled with drain rock, with several inches placed inside the casing to help control the pumping of fines. Submersible pumps (trash pumps) are then placed inside the casing and connected to a central discharge pipe. The Contractor should be responsible for design, implementation, and any necessary permits associated with any construction dewatering system used for the Project. ASPECT CONSULTING PROJECT NO. 210421  DECEMBER 21, 2023 FINAL 15 5 Recommendations for Continuing Geotechnical Services This report is provided to summarize our key findings and conclusions in support of the future Project design. Site grading, civil plans, and construction methods were at the 90 percent complete level at the time of this final report. Throughout this report, we have provided recommendations where we consider it would be appropriate for Aspect to provide additional geotechnical input to the design and construction process. Additional recommendations are summarized in this section. 5.1 Additional Design and Consultation Services Before construction begins, we recommend that Aspect: • Continue to meet with the design team as needed to address geotechnical questions that may arise during the final PS&E preparation. • Review the geotechnical elements of the Project plans to see that our recommendations are properly interpreted and incorporated into the design. 5.2 Additional Construction Services Aspect is available to provide geotechnical engineering and monitoring services during construction. The integrity of the geotechnical elements depends on proper Site preparation and construction procedures. In addition, engineering decisions may have to be made in the field in the event that variations in subsurface conditions become apparent. During the construction phase of the Project, we recommend that Aspect be retained to perform the following tasks: • Review applicable submittals • Observe and evaluate subgrade preparation and structural fill placement for pavement and retaining walls • Attend meetings, as needed • Address other geotechnical engineering considerations that may arise during construction The purpose of our observations is to verify compliance with design concepts and recommendations and to allow design changes or evaluation of appropriate construction methods in the event that subsurface conditions differ from those anticipated prior to the start of construction. ASPECT CONSULTING 16 FINAL PROJECT NO. 210421  DECEMBER 21, 2023 6 References ASTM International (ASTM), 2018, Annual Book of Standards, Vol. 4.08, West Conshohocken, Pennsylvania. Atwater, B. F., 2015, The orphan tsunami of 1700: Japanese clues to a parent earthquake in North America. U. 475 S. Geological Survey Professional Paper 1707 [first published 2005]. 135 pp. 476 https://doi.org/10.3133/pp1707. Gower H.D., J.C. Yount, and R.S. Crosson (Gower et al.), 1985, Seismotectonic map of the Puget Sound region, Washington: U.S. Geological Survey Miscellaneous Investigations Series Map I-1613, p. 15, plate 1, scale 1:250,000. Jefferson County ArcGIS Web Portal, (County) 2023, web application. (n.d.). https://gisweb.jeffcowa.us/LandRecords/ Otak, Inc. (Otak), 2023, Olympic Discovery Trail Andersen Lake Connection, 90 % Plans, Drawings, October 2023. Pratt, T.L., K.G. Troost, J.K. Odum, and W.J. Stephenson (Pratt et al.), 2015, Kinematics of shallow backthrusts in the Seattle fault zone, Washington State, Geosphere, v. 11, no. 6, p. 1–27, doi:10.1130/GES01179.1. Schasse, H.W., and Slaughter, S.L., 2005, Geologic map of the Port Townsend South and part of the Port Townsend North 7.5-minute quadrangles, Jefferson County, Washington, Scale: 1:24000, 2005. Varnes, DJ, 1978, Slope movement types and processes. In: Schuster RL, Krizek RJ (eds) Landslides, analysis and control, special report 176: Transportation research board, National Academy of Sciences, Washington, DC., pp. 11–33 Washington Administrative Code (WAC), 2020, Chapter 296-155, Part N - Excavation, Trenching, and Shoring, April 20, 2020. Washington State Department of Ecology (Ecology), 2019, Stormwater Management Manual for Western Washington, Publication Number 14-10-055, December 2019. Washington State Department of Natural Resources (DNR), 2023, Washington Geologic Information Portal, Accessed October 2023 from https://geologyportal.dnr.wa.gov/. Washington State Department of Transportation (WSDOT), 2023, Standard Specifications for Road, Bridge and Municipal Construction, Document M 41-10. ASPECT CONSULTING PROJECT NO. 210421  DECEMBER 21, 2023 FINAL 17 7 Limitations Work for this project was performed for Otak, Inc. (Client), and this report was prepared consistent with recognized standards of professionals in the same locality and involving similar conditions, at the time the work was performed. No other warranty, expressed or implied, is made by Aspect Consulting (Aspect). Recommendations presented herein are based on our interpretation of site conditions, geotechnical engineering calculations, and judgment in accordance with our mutually agreed-upon scope of work. Our recommendations are unique and specific to the project, site, and Client. Application of this report for any purpose other than the project should be done only after consultation with Aspect. Variations may exist between the soil and groundwater conditions reported and those actually underlying the site. The nature and extent of such soil variations may change over time and may not be evident before construction begins. If any soil conditions are encountered at the site that are different from those described in this report, Aspect should be notified immediately to review the applicability of our recommendations. Risks are inherent with any site involving slopes and no recommendations, geologic analysis, or engineering design can assure slope stability. Our observations, findings, and opinions are a means to identify and reduce the inherent risks to the Client. It is the Client's responsibility to see that all parties to this project, including the designer, contractor, subcontractors, and agents, are made aware of this report in its entirety. At the time of this report, design plans and construction methods have not been finalized, and the recommendations presented herein are based on preliminary project information. If project developments result in changes from the preliminary project information, Aspect should be contacted to determine if our recommendations contained in this report should be revised and/or expanded upon. The scope of work does not include services related to construction safety precautions. Site safety is typically the responsibility of the contractor, and our recommendations are not intended to direct the contractor’s site safety methods, techniques, sequences, or procedures. The scope of our work also does not include the assessment of environmental characteristics, particularly those involving potentially hazardous substances in soil or groundwater. All reports prepared by Aspect for the Client apply only to the services described in the Agreement(s) with the Client. Any use or reuse by any party other than the Client is at the sole risk of that party, and without liability to Aspect. Aspect’s original files/reports shall govern in the event of any dispute regarding the content of electronic documents furnished to others. Please refer to Appendix D titled “Report Limitations and Guidelines for Use” for additional information governing the use of this report. We appreciate the opportunity to perform these services. If you have any questions please call Erik Andersen, Principal Geotechnical Engineer, at 425-772-4705 FIGURES SITE LOCATION Port Townsend SITE LOCATION£¤101 IDAHOOREGON WASHINGTON Bellingham SpokaneSeattleWenatchee Olympia Yakima Tacoma SITE LOCATION Data source credits: None || Basemap Service Layer Credits: Island County, WA State Parks GIS, Esri, HERE, Garmin, SafeGraph, FAO, METI/NASA, USGS, Bureau of Land Management, EPA, NPS,Esri, NASA, NGA, USGS, Island County, Bureau of Land Management, Esri Canada, Esri, HERE, Garmin, INCREMENT P, USGS, METI/NASA, EPA, USDA, Esri, HERE, Garmin, USGS, EPA GIS Path: G:\projects\OlympicDiscoveryTrail_210421\OlympicDiscoveryTrail_210421.aprx: 01 Site Location Map|| User: haley.duran || Print Date: 10/30/2023OCT-2023 HMD STM / NLK 210421 1 FIGURE NO. REVISED BY: BY: PROJECT NO. Site Location Map Final Geotechnical Report Olympic Discovery Trail, Port Townsend, WA 98368 0 1,000 2,000 Feet ED ED ED ED ED ED ED ED ED ED ED #*Ó ! ! ! ! ! ! !!! ! ! ! ! ! ! ! ! ! S DISC O V E R Y R D HWY 20KEYS TONE PL FOUR CORNERSRD AERIE LNNIGHTOWLRDMAL A M UT E L NS OU T HPO R T LNADELMA BEACHRD3002004 0 0100100 3 0030 0300300300 300100ATP-01 ATP-02 ATP-03 ATP-04 ATP-05 ATP-06 ATP-07 ATP-08 ATP-09 ATP-11 ATP-10 AHA-01 90+00 80+00 70+00 60+00 50+00 40+00 30+00 20+00 10+00 180+00 170+00 160+00 150+00 140+00 130+00 120+00 110+00 100+00 Data source credits: None || Basemap Service Layer Credits: © OpenStreetMap (and) contributors, CC-BY-SA, Google Maps GIS Path: G:\projects\OlympicDiscoveryTrail_210421\OlympicDiscoveryTrail_210421.aprx: 02 Site and Exploration Map|| User: haley.duran || Print Date: 12/13/2023OCT-2023 HMD STM / NLK 210421 2FIGURE NO. REVISED BY: BY: PROJECT NO. Site and Exploration Map Final Geotechnical Report Olympic Discovery Trail, Port Townsend, WA 98368 #*Ó Hand Auger ED Test Pit 100-foot Topography Contours 20-foot Topography Contours 0 400 800 Feet APPENDIX A Subsurface Exploration Logs ASPECT CONSULTING PROJECT NO. 210421  DECEMBER 21, 2023 FINAL A-1 A. Subsurface Explorations by Aspect Aspect performed a field exploration program between August 28 and August 30, 2023, to determine the geotechnical and hydrogeological properties of materials at the Site. High Meadows Excavating LLC, under subcontract to Aspect, completed 11 test pits, designated ATP-01, through ATP-11. Excavation was conducted using a Hitachi 85USB track excavator to depths ranging between 7.5 and 9.25 feet bgs. The test pits were excavated using a ZAXIS 85 USB tracked excavator and backfilled with excavated soils, tamped into place using the excavator bucket. An Aspect engineer-in-training was present throughout the program to observe the excavation procedures, assist in sampling, and prepare descriptive logs of the explorations. Soils were classified in general accordance with ASTM International (ASTM) D2488, Standard Practice for Description and Identification of Soils (Visual-Manual Procedure). The relative density/consistency of the soils was evaluated qualitatively with a 0.5-inch-diameter steel T-probe and observation of digging difficulty. Exploration locations are shown on Figure 2, and the exploration logs are provided within this appendix. The summary exploration logs represent our interpretation of the contents of the field logs. The stratigraphic contacts shown on the individual summary logs represent the approximate boundaries between soil types; actual transitions may be more gradual. The subsurface conditions depicted are only for the specific date and locations reported and are not necessarily representative of other locations and times. AI Path: Q:\_ACAD Standards\FIELD REFERENCE\MASTERS\Exploration Log Key-2018.ai // user: jinman // last saved: 12/31/2018“WITH SILT” or “WITH CLAY” means 5 to 15% silt and clay, denoted by a “-“ in the groupname; e.g., SP-SM ● “SILTY” or “CLAYEY” means >15% silt and clay ● “WITH SAND” or “WITHGRAVEL” means 15 to 30% sand and gravel. ● “SANDY” or “GRAVELLY” means >30% sand andgravel. ● “Well-graded” means approximately equal amounts of fine to coarse grain sizes ● “Poorlygraded” means unequal amounts of grain sizes ● Group names separated by “/” means soilcontains layers of the two soil types; e.g., SM/ML. Soils were described and identified in the field in general accordance with the methods described inASTM D2488. Where indicated in the log, soils were classified using ASTM D2487 or otherlaboratory tests as appropriate. Refer to the report accompanying these exploration logs for details. % by Weight Density³SPT² Blows/Foot HighlyOrganicSoilsFine-Grained Soils - 50%1 or More Passes No. 200 SieveCoarse-Grained Soils - More than 50%1 Retained on No. 200 SieveGravels - More than 50%1 of Coarse FractionRetained on No. 4 Sieve15% Fines5% FinesSands - 50%1 or More of Coarse FractionPasses No. 4 SieveSilts and ClaysLiquid Limit Less than 50%Silts and ClaysLiquid Limit 50% or More15% Fines5% FinesWell-graded GRAVELWell-graded GRAVEL WITH SAND Poorly-graded GRAVELPoorly-graded GRAVEL WITH SAND SILTY GRAVEL SILTY GRAVEL WITH SAND CLAYEY GRAVEL CLAYEY GRAVEL WITH SAND Well-graded SAND Well-graded SAND WITH GRAVEL Poorly-graded SANDPoorly-graded SAND WITH GRAVEL SILTY SAND SILTY SAND WITH GRAVEL CLAYEY SANDCLAYEY SAND WITH GRAVEL SILTSANDY or GRAVELLY SILTSILT WITH SANDSILT WITH GRAVEL LEAN CLAYSANDY or GRAVELLY LEAN CLAYLEAN CLAY WITH SANDLEAN CLAY WITH GRAVEL ORGANIC SILT SANDY or GRAVELLY ORGANIC SILTORGANIC SILT WITH SANDORGANIC SILT WITH GRAVEL ELASTIC SILTSANDY or GRAVELLY ELASTIC SILT ELASTIC SILT WITH SAND ELASTIC SILT WITH GRAVEL FAT CLAYSANDY or GRAVELLY FAT CLAYFAT CLAY WITH SANDFAT CLAY WITH GRAVEL ORGANIC CLAYSANDY or GRAVELLY ORGANIC CLAYORGANIC CLAY WITH SAND ORGANIC CLAY WITH GRAVEL PEAT and other mostly organic soils GW GP GM GC SW SP SM SC ML CL OL MH CH OH PT Modifier Organic Chemicals BTEX =Benzene, Toluene, Ethylbenzene, Xylenes TPH-Dx =Diesel and Oil-Range Petroleum HydrocarbonsTPH-G =Gasoline-Range Petroleum HydrocarbonsVOCs=Volatile Organic Compounds SVOCs =Semi-Volatile Organic CompoundsPAHs=Polycyclic Aromatic Hydrocarbon CompoundsPCBs=Polychlorinated Biphenyls GEOTECHNICAL LAB TESTSMC=Natural Moisture ContentPS=Particle Size DistributionFC=Fines Content (% < 0.075 mm)GH =Hydrometer TestAL=Atterberg LimitsC=Consolidation TestStr=Strength TestOC=Organic Content (% Loss by Ignition)Comp =Proctor TestK=Hydraulic Conductivity TestSG=Specific Gravity Test RCRA8 =As, Ba, Cd, Cr, Pb, Hg, Se, Ag, (d = dissolved, t = total) MTCA5 =As, Cd, Cr, Hg, Pb (d = dissolved, t = total)PP-13 =Ag, As, Be, Cd, Cr, Cu, Hg, Ni, Pb, Sb, Se, Tl, Zn (d=dissolved, t=total) CHEMICAL LAB TESTS PID =Photoionization Detector Sheen =Oil Sheen TestSPT2=Standard Penetration TestNSPT=Non-Standard Penetration Test DCPT =Dynamic Cone Penetration Test <1 =Subtrace1 to <5 =Trace5 to 10 =Few Dry =Absence of moisture, dusty, dry to the touch Slightly Moist =Perceptible moistureMoist=Damp but no visible waterVery Moist =Water visible but not free draining Wet = Visible free water, usually from below water table COMPONENT DEFINITIONSDescriptive Term Size Range and Sieve Number Boulders = Larger than 12 inchesCobbles=3 inches to 12 inches Coarse Gravel =3 inches to 3/4 inchesFine Gravel =3/4 inches to No. 4 (4.75 mm)Coarse Sand =No. 4 (4.75 mm) to No. 10 (2.00 mm) Medium Sand =No. 10 (2.00 mm) to No. 40 (0.425 mm) Fine Sand =No. 40 (0.425 mm) to No. 200 (0.075 mm)Silt and Clay =Smaller than No. 200 (0.075 mm) Metals ESTIMATED1 PERCENTAGE MOISTURE CONTENT RELATIVE DENSITY CONSISTENCY GEOLOGIC CONTACTS Very Loose =0 to 4 ≥2'Loose =5 to 10 1' to 2'Medium Dense =11 to 30 3" to 1'Dense =31 to 50 1" to 3"Very Dense => 50 < 1" Consistency³ Very Soft =0 to 1 Penetrated >1" easily by thumb. Extrudes between thumb & fingers.Soft =2 to 4 Penetrated 1/4" to 1" easily by thumb. Easily molded.Medium Stiff =5 to 8 Penetrated >1/4" with effort by thumb. Molded with strong pressure.Stiff =9 to 15 Indented ~1/4" with effort by thumb.Very Stiff =16 to 30 Indented easily by thumbnail.Hard => 30 Indented with difficulty by thumbnail. Non-Cohesive or Coarse-Grained Soils SPT² Blows/Foot Observed and Distinct Observed and Gradual Inferred 1.Estimated or measured percentage by dry weight2.(SPT) Standard Penetration Test (ASTM D1586)3.Determined by SPT, DCPT (ASTM STP399) or other field methods. See report text for details. % by Weight Modifier 15 to 25 =Little30 to 45 =Some>50 =Mostly Penetration with 1/2" Diameter Rod Manual Test FIELD TESTS Cohesive or Fine-Grained Soils Exploration Log Key TOPSOIL SILTY SAND WITH GRAVEL (SM); medium dense, dry, brown; fine to coarse sand; fine to coarse, rounded tosubangular gravel; few cobbles to 3-inches diameter;abundant roots. Pleistocene Continental Glacial Till (Qgt) SILTY SAND WITH GRAVEL (SM); very dense, dry, lightbrown; fine to coarse sand; fine to coarse, rounded tosubangualr gravel; few cobbles. Bottom of exploration at 2 ft. bgs. Operator Work Start/Completion Dates Blows/footWater Content (%) Equipment Legend Contractor 354 353 352 351 350 349 348 347 346 AHA-01 Tests Hand auger Hand tools Aspect Exploration Method(s) See Exploration Log Key for explanationof symbols SampleType/ID Depth to Water (Below GS) Description NA No Water Encountered Ground Surface Elev. (NAVD88) Exploration Notes andCompletion Details Blows/6" Coordinates (Lat,Lon WGS84) Grab Logged by: MRHApproved by: EOA Top of Casing Elev. (NAVD88) 1 2 3 4 5 6 7 8 9 8/29/2023 Project Address & Site Specific Location 355' (est) Plastic Limit 48.0206, -122.8138 (est)AHA-01 Depth(feet)MaterialType Monica Hill SampleTypeElev.(feet) No Water Encountered Liquid Limit Geotechnical Exploration Log 1 2 3 4 5 6 7 8 9 63 4 Corners Rd, Port Townsend, See Figure 2. ExplorationLog Exploration Number WaterLevelSheet 1 of 1 Depth(ft) Sampling Method NEW STANDARD EXPLORATION LOG TEMPLATE P:\GINTW\PROJECTS\210421 - OLYMPIC DISCOVERY TRAIL.GPJ October 30, 2023Olympic Discovery Trail - 210421 10 20 30 400 50 Backfilled withexcavated material. T-probe=0"-2" T-probe=0"-1" PS FC=6% TOPSOIL; loose, dry, dark brown Everson Interstade Glaciomarine Outwash (Qgom(e)) SAND WITH SILT (SP-SM); dense, dry, brown; fine tocoarse, cemented sand; trace, fine to coarse, subangularto rounded gravel; trace organics; iron-oxide staining. SAND WITH SILT (SP-SM); dense, slightly moist to moist, brown; fien to coarse sand; fine to coarse, trace,subangular to rounded gravel. Bottom of exploration at 9.75 ft. bgs.S1S2S3Operator Work Start/Completion Dates Blows/footWater Content (%) Equipment Legend Contractor 135 130 125 120 ATP-01 Tests ZAXIS 85USB Backhoe or trackhoe High Meadows Excavation Exploration Method(s) See Exploration Log Key for explanationof symbols SampleType/ID Depth to Water (Below GS) Description NA Grab sample No Water Encountered Ground Surface Elev. (NAVD88) Exploration Notes andCompletion Details Blows/6" Coordinates (Lat,Lon WGS84) Grab Logged by: STMApproved by: EOA Top of Casing Elev. (NAVD88) 5 10 15 8/28/2023 Project Address & Site Specific Location 138' (est) Plastic Limit 48.0497, -122.8244 (est)ATP-01 Depth(feet)MaterialType Andrew Monsaas SampleTypeElev.(feet) No Water Encountered Liquid Limit Geotechnical Exploration Log 5 10 15 63 4 Corners Rd, Port Townsend, See Figure 2. ExplorationLog Exploration Number WaterLevelSheet 1 of 1 Depth(ft) Sampling Method NEW STANDARD EXPLORATION LOG TEMPLATE P:\GINTW\PROJECTS\210421 - OLYMPIC DISCOVERY TRAIL.GPJ October 30, 2023Olympic Discovery Trail - 210421 10 20 30 400 50 4 Backfilled withexcavated material T-probe=0"-1" T-probe=0"-1" PSFC=4.5% PSFC=7.7% TOPSOIL; loose, dry, dark brown Everson Interstade Glaciomarine Outwash (Qgom(e)) SILTY SAND (SM); medium dense, slightly moist, light brown; fine to medium sand; slightly cemented; iron-oxidestaining; few organics. SILTY SAND WITH GRAVEL (SM); medium dense, slightly moist, brown;fine to coarse sand; fine to coarse, angular to subrounded gravel; trace organics. SAND WITH SILT (SP-SM); medium dense to dense,slightly moist, brown;fine to coarse sand; trace, fine to coarse, angular to subrounded gravel; trace organics;slight cementation. Bottom of exploration at 10 ft. bgs.S1S2S3S4S5Operator Work Start/Completion Dates Blows/footWater Content (%) Equipment Legend Contractor 135 130 125 120 ATP-02 Tests ZAXIS 85USB Backhoe or trackhoe High Meadows Excavation Exploration Method(s) See Exploration Log Key for explanationof symbols SampleType/ID Depth to Water (Below GS) Description NA Grab sample No Water Encountered Ground Surface Elev. (NAVD88) Exploration Notes andCompletion Details Blows/6" Coordinates (Lat,Lon WGS84) Grab Logged by: STMApproved by: EOA Top of Casing Elev. (NAVD88) 5 10 15 8/28/2023 Project Address & Site Specific Location 138' (est) Plastic Limit 48.0495, -122.8206 (est)ATP-02 Depth(feet)MaterialType Andrew Monsaas SampleTypeElev.(feet) No Water Encountered Liquid Limit Geotechnical Exploration Log 5 10 15 63 4 Corners Rd, Port Townsend, See Figure 2. ExplorationLog Exploration Number WaterLevelSheet 1 of 1 Depth(ft) Sampling Method NEW STANDARD EXPLORATION LOG TEMPLATE P:\GINTW\PROJECTS\210421 - OLYMPIC DISCOVERY TRAIL.GPJ October 30, 2023Olympic Discovery Trail - 210421 10 20 30 400 50 3 3.7 Backfilled withexcavated material. T-probe=0"-0.5" AL =NP PSFC=3.6% PSFC=1.8% Everson Interstade Glaciomarine Outwash (Qgom(e)) SILT (ML); hard, slightly moist, gray-brown; low plasticity; trace, fine to coarse sand; subtrace organics. SILTY SAND (SM); dense, moist, brown; fine to coarsesand. SILTY SAND (SM); dense, moist, brown to dark brown;fine to coarse sand; fine to coarse, subangular to rounded gravel. SAND (SP); dense, wet, gray; fine to coarse sand; fine tocoarse, subangular to subrounded gravel. GRAVEL WITH SAND (GW); dense, wet, gray; fine tocoarse sand; fine to coarse, subangular to subrounded gravel. Bottom of exploration at 9 ft. bgs.S1S2S3S4Operator Work Start/Completion Dates Blows/footWater Content (%) Equipment Legend Contractor 140 135 130 125 ATP-03 Tests ZAXIS 85USB Backhoe or trackhoe High Meadows Excavation Exploration Method(s) See Exploration Log Key for explanationof symbols SampleType/ID Depth to Water (Below GS) Description NA Grab sample No Water Encountered Ground Surface Elev. (NAVD88) Exploration Notes andCompletion Details Blows/6" Coordinates (Lat,Lon WGS84) Grab Logged by: STMApproved by: EOA Top of Casing Elev. (NAVD88) 5 10 15 8/28/2023 Project Address & Site Specific Location 141' (est) Plastic Limit 48.0488, -122.8163 (est)ATP-03 Depth(feet)MaterialType Andrew Monsaas SampleTypeElev.(feet) No Water Encountered Liquid Limit Geotechnical Exploration Log 5 10 15 63 4 Corners Rd, Port Townsend, See Figure 2. ExplorationLog Exploration Number WaterLevelSheet 1 of 1 Depth(ft) Sampling Method NEW STANDARD EXPLORATION LOG TEMPLATE P:\GINTW\PROJECTS\210421 - OLYMPIC DISCOVERY TRAIL.GPJ October 30, 2023Olympic Discovery Trail - 210421 10 20 30 400 50 19.2 9.4 3.6 Backfilled withexcavated material. T-probe=1"-3" T-probe=1"-2" FCFC=80.5% PSFC=6.5% Everson Interstade Glaciomarine Outwash (Qgom(e)) SILT WITH SAND (ML); medium stiff to stiff, slightly moist to moist, gray-brown; low plasticity; fine to coarsesand; few, fine to coarse, subangular to rounded gravel. GRAVEL WITH SAND (GP); dense, moist, brown; fine tocoarse sand; fine to coarse, subangular to rounded gravel. SAND WITH SILT AND GRAVEL (SW-SM); dense, very moist, brown; fine to coarse sand; fine to coarse, subangular to rounded gravel. Interbedded 8-to-12-inch thick silt lense. SILTY GRAVEL WITH SAND (GM); dense, very moist, brown; fine to coarse sand; fine to coarse, subangular torounded gravel. Bottom of exploration at 15 ft. bgs.S1S2S3S4S5S6S7Operator Work Start/Completion Dates Blows/footWater Content (%) Equipment Legend Contractor 135 130 125 120 ATP-04 Tests ZAXIS 85USB Backhoe or trackhoe High Meadows Excavation Exploration Method(s) See Exploration Log Key for explanationof symbols SampleType/ID Depth to Water (Below GS) Description NA Grab sample No Water Encountered Ground Surface Elev. (NAVD88) Exploration Notes andCompletion Details Blows/6" Coordinates (Lat,Lon WGS84) Grab Logged by: STMApproved by: EOA Top of Casing Elev. (NAVD88) 5 10 15 8/28/2023 Project Address & Site Specific Location 137' (est) Plastic Limit 48.0471, 122.8158 (est)ATP-04 Depth(feet)MaterialType Andrew Monsaas SampleTypeElev.(feet) No Water Encountered Liquid Limit Geotechnical Exploration Log 5 10 15 63 4 Corners Rd, Port Townsend, See Figure 2. ExplorationLog Exploration Number WaterLevelSheet 1 of 1 Depth(ft) Sampling Method NEW STANDARD EXPLORATION LOG TEMPLATE P:\GINTW\PROJECTS\210421 - OLYMPIC DISCOVERY TRAIL.GPJ October 30, 2023Olympic Discovery Trail - 210421 10 20 30 400 50 Backfilled withexcavated material. T-probe=1"-3" T-probe=0"-1" PSFC=2.6% TOPSOIL; loose, dry, dark brown Pleistocene Glacial Continental Drift (Qgo) SILTY SAND WITH GRAVEL AND COBBLES (SM); dense, dry, brown; fine to coarse sand; fine to coarse,subangular to rounded gravel; subtrace organics. Pleistocene Glacial Continental Drift (Qga) GRAVEL WITH SAND (GP); very dense, moist, brown; fine to coarse sand; fine to coarse, subrounded to roundedgravel. SAND WITH SILT AND GRAVEL (SP-SM); very dense,moist, brown; fine to coarse sand; fine to coarse, subrounded to rounded gravel. SAND WITH SILT (SP-SM); very dense, moist, brown;fine to coarse sand; trace, fine to coarse, subrounded torounded gravel. Bottom of exploration at 14 ft. bgs.S1S2S3S4S5S6Operator Work Start/Completion Dates Blows/footWater Content (%) Equipment Legend Contractor 155 150 145 140 ATP-05 Tests ZAXIS 85USB Backhoe or trackhoe High Meadows Excavation Exploration Method(s) See Exploration Log Key for explanationof symbols SampleType/ID Depth to Water (Below GS) Description NA Grab sample No Water Encountered Ground Surface Elev. (NAVD88) Exploration Notes andCompletion Details Blows/6" Coordinates (Lat,Lon WGS84) Grab Logged by: STMApproved by: EOA Top of Casing Elev. (NAVD88) 5 10 15 8/28/2023 Project Address & Site Specific Location 158' (est) Plastic Limit 48.0430, -122.8164 (est)ATP-05 Depth(feet)MaterialType Andrew Monsaas SampleTypeElev.(feet) No Water Encountered Liquid Limit Geotechnical Exploration Log 5 10 15 63 4 Corners Rd, Port Townsend, See Figure 2. ExplorationLog Exploration Number WaterLevelSheet 1 of 1 Depth(ft) Sampling Method NEW STANDARD EXPLORATION LOG TEMPLATE P:\GINTW\PROJECTS\210421 - OLYMPIC DISCOVERY TRAIL.GPJ October 30, 2023Olympic Discovery Trail - 210421 10 20 30 400 50 1.7 Backfilled withexcavated material. T-probe=1"-2" T-probe=0"-1" PSFC=8.4% AL = NP TOPSOIL; loose, dry, dark brown Pleistocene Continental Glacial Till (Qgt) GRAVEL WITH SILT AND SAND (GP-GM); mediumdense to dense, slightly moist, brown; fine to coarse sand;fine to coarse, subangular to rounded gravel; somecementation. Becomes moist. SILT (ML); hard, slightly moist to moist, gray-brown; lowplasticity; iron-oxide staining. Bottom of exploration at 16.5 ft. bgs.S1S2S3S4S5S6Operator Work Start/Completion Dates Blows/footWater Content (%) Equipment Legend Contractor 215 210 205 ATP-06 Tests ZAXIS 85USB Backhoe or trackhoe High Meadows Excavation Exploration Method(s) See Exploration Log Key for explanationof symbols SampleType/ID Depth to Water (Below GS) Description NA Grab sample No Water Encountered Ground Surface Elev. (NAVD88) Exploration Notes andCompletion Details Blows/6" Coordinates (Lat,Lon WGS84) Grab Logged by: STMApproved by: EOA Top of Casing Elev. (NAVD88) 5 10 15 8/28/2023 Project Address & Site Specific Location 220' (est) Plastic Limit 48.0419, -122.8163 (est)ATP-06 Depth(feet)MaterialType Andrew Monsaas SampleTypeElev.(feet) No Water Encountered Liquid Limit Geotechnical Exploration Log 5 10 15 63 4 Corners Rd, Port Townsend, See Figure 2. ExplorationLog Exploration Number WaterLevelSheet 1 of 1 Depth(ft) Sampling Method NEW STANDARD EXPLORATION LOG TEMPLATE P:\GINTW\PROJECTS\210421 - OLYMPIC DISCOVERY TRAIL.GPJ October 30, 2023Olympic Discovery Trail - 210421 10 20 30 400 50 6.1 16.1 TOPSOIL SILTY SAND (SM); loose, slightly moist, brown; abundant roots. Pleistocene Continental Glacial Till (Qgt) SILTY SAND WITH GRAVEL (SM); very dense, slightly moist, light brown; fine to coarse sand; fine to coarse,rounded to subangular gravel; few cobbles; cemented. SILTY SAND WITH GRAVEL (SM); very dense, slightly moist, gray brown; fine to coarse sand; fine to coarse,rounded to subangular gravel; few cobbles; blocky;hardpan. SILT (ML); medium stiff, moist, brown; nonplastic; tracefine sand; oxidized laminations; trace dark organics. Becomes gray. Becomes hard. 0.5-foot-thick oxidized layer. Bottom of exploration at 15 ft. bgs.S1S2S3S4S5Operator Work Start/Completion Dates Blows/footWater Content (%) Equipment Legend Contractor 280 275 270 ATP-07 Tests ZAXIS 85USB Backhoe or trackhoe High Meadows Excavation Exploration Method(s) See Exploration Log Key for explanationof symbols SampleType/ID Depth to Water (Below GS) Description NA No Water Encountered Ground Surface Elev. (NAVD88) Exploration Notes andCompletion Details Blows/6" Coordinates (Lat,Lon WGS84) Grab Logged by: MRHApproved by: EOA Top of Casing Elev. (NAVD88) 5 10 15 8/28/2023 Project Address & Site Specific Location 285' (est) Plastic Limit 48.0372, -122.8181 (est)ATP-07 Depth(feet)MaterialType Andrew Monsaas SampleTypeElev.(feet) No Water Encountered Liquid Limit Geotechnical Exploration Log 5 10 15 63 4 Corners Rd, Port Townsend, See Figure 2. ExplorationLog Exploration Number WaterLevelSheet 1 of 1 Depth(ft) Sampling Method NEW STANDARD EXPLORATION LOG TEMPLATE P:\GINTW\PROJECTS\210421 - OLYMPIC DISCOVERY TRAIL.GPJ October 30, 2023Olympic Discovery Trail - 210421 10 20 30 400 50 PSFC=9.6% TOPSOIL SILTY SAND WITH GRAVEL (SM); medium dense, moist, brown; abundant roots. Pleistocene Glacial Continental Drift (Qga) SILTY SAND WITH GRAVEL AND COBBLES (SM); very dense, dry, light brown; fine to coarse sand; fine to coarse,rounded to subangular gravel; few cobbles. GRAVEL WITH SILT AND SAND (GP-GM); very dense,slightly moist, gray brown; fine to coarse sand; fine to coarse, rounded to subangular gravel; few cobbles to12-inches-diameter; hardpan. Becomes slightly oxidized. GRAVEL WITH CLAY AND SAND (GP-GC); dense,moist, gray brown; fine to coarse sand; fine to trace coarse, subrounded to subangular gravel. GRAVEL WITH CLAY AND COBBLES (GP-GC); dense,very moist, gray; fine to coarse sand; fine to coarse, subrounded to subangular gravel; few cobbles. Bottom of exploration at 12.5 ft. bgs.S1S2S3S4S5Operator Work Start/Completion Dates Blows/footWater Content (%) Equipment Legend Contractor 335 330 325 320 ATP-08 Tests ZAXIS 85USB Backhoe or trackhoe High Meadows Excavation Exploration Method(s) See Exploration Log Key for explanationof symbols SampleType/ID Depth to Water (Below GS) Description NA Grab sample No Water Encountered Ground Surface Elev. (NAVD88) Exploration Notes andCompletion Details Blows/6" Coordinates (Lat,Lon WGS84) Grab Logged by: MRHApproved by: EOA Top of Casing Elev. (NAVD88) 5 10 15 8/28/2023 Project Address & Site Specific Location 337' (est) Plastic Limit 48.0263, -122.8215 (est)ATP-08 Depth(feet)MaterialType Andrew Monsaas SampleTypeElev.(feet) No Water Encountered Liquid Limit Geotechnical Exploration Log 5 10 15 63 4 Corners Rd, Port Townsend, See Figure 2. ExplorationLog Exploration Number WaterLevelSheet 1 of 1 Depth(ft) Sampling Method NEW STANDARD EXPLORATION LOG TEMPLATE P:\GINTW\PROJECTS\210421 - OLYMPIC DISCOVERY TRAIL.GPJ October 30, 2023Olympic Discovery Trail - 210421 10 20 30 400 50 5.1 PSFC=7.9% TOPSOIL SILTY SAND WITH GRAVEL AND COBBLES (SM); medium dense, slightly moist, brown; abundant roots. Pleistocene Glacial Continental Drift (Qgo) SAND WITH SILT, GRAVEL, AND COBBLES (SP-SM);very dense, dry, light brown; fine to coarse sand; fine tocoarse, rounded to subangular gravel; rounded tosubangular cobbles; boulders to 2-feet-diameter. Becomes with more gravel. Pleistocene Continental Glacial Till (Qgt) GRAVEL WITH SILT, SAND, AND COBBLES (GP-GM);very dense, slightly moist, gray brown; fine to coarse sand;fine to coarse, rounded to subangular gravel; rounded tosubangular cobbles; slight iron-oxide staining; hardpan. Perched groundwater encountered at 7 feet bgs in cobble and boulder layer. Becomes with fewer cobbles. Bottom of exploration at 13 ft. bgs. 8/29/2023 S1S2Operator Work Start/Completion Dates Blows/footWater Content (%) Equipment Legend Contractor 310 305 300 ATP-09 Water Level (Seepage) Tests ZAXIS 85USB Backhoe or trackhoe High Meadows Excavation Exploration Method(s) See Exploration Log Key for explanationof symbols SampleType/ID Depth to Water (Below GS) Description NA Grab sample Ground Surface Elev. (NAVD88) Exploration Notes andCompletion Details Blows/6" Coordinates (Lat,Lon WGS84) Grab Logged by: MRHApproved by: EOA Top of Casing Elev. (NAVD88) 5 10 15 8/28/2023 Project Address & Site Specific Location 315' (est) Plastic Limit 48.0252, -122.8217 (est)ATP-09 Depth(feet)MaterialType Andrew Monsaas SampleTypeElev.(feet) Liquid Limit Geotechnical Exploration Log 5 10 15 63 4 Corners Rd, Port Townsend, See Figure 2. ExplorationLog Exploration Number WaterLevelSheet 1 of 1 Depth(ft) Sampling Method NEW STANDARD EXPLORATION LOG TEMPLATE P:\GINTW\PROJECTS\210421 - OLYMPIC DISCOVERY TRAIL.GPJ October 30, 2023Olympic Discovery Trail - 210421 10 20 30 400 50 1.3 Backfilled withexcavated material. TOPSOIL SILTY SAND WITH GRAVEL (SM); loose, slightly moist, brown; fine to coarse sand; fine, subrounded to subangulargravel; abundant roots; charcoal. Pleistocene Continental Glacial Drift (Qgo) SILTY SAND WITH GRAVEL (SM); medium dense, dry to slightly moist, light brown; fine to coarse sand; fine tocoarse, rounded to subangular gravel; slight iron-oxide staining; roots to 1.5 feet bgs. Pleistocene Continental Glacial Till (Qgt) SILTY SAND WITH GRAVEL (SM); very dense, slightly moist, gray brown; fine to coarse sand; fine to coarse,rounded to subangular gravel; few cobbles; hardpan. Bottom of exploration at 5 ft. bgs.S1Operator Work Start/Completion Dates Blows/footWater Content (%) Equipment Legend Contractor 386 385 384 383 382 381 380 379 378 ATP-10 Tests ZAXIS 85USB Backhoe or trackhoe High Meadows Excavation Exploration Method(s) See Exploration Log Key for explanationof symbols SampleType/ID Depth to Water (Below GS) Description NA Grab sample No Water Encountered Ground Surface Elev. (NAVD88) Exploration Notes andCompletion Details Blows/6" Coordinates (Lat,Lon WGS84) Grab Logged by: MRHApproved by: EOA Top of Casing Elev. (NAVD88) 1 2 3 4 5 6 7 8 9 8/29/2023 Project Address & Site Specific Location 387' (est) Plastic Limit 48.0210, -122.8215 (est)ATP-10 Depth(feet)MaterialType Andrew Monsaas SampleTypeElev.(feet) No Water Encountered Liquid Limit Geotechnical Exploration Log 1 2 3 4 5 6 7 8 9 63 4 Corners Rd, Port Townsend, See Figure 2. ExplorationLog Exploration Number WaterLevelSheet 1 of 1 Depth(ft) Sampling Method NEW STANDARD EXPLORATION LOG TEMPLATE P:\GINTW\PROJECTS\210421 - OLYMPIC DISCOVERY TRAIL.GPJ October 30, 2023Olympic Discovery Trail - 210421 10 20 30 400 50 TOPSOIL SILTY SAND WITH GRAVEL (SM); medium dense, slightly moist, brown; fine to coarse sand; fine to tracecoarse, rounded to subangular gravel; abundant roots;charcoal; slight iron-oxide staining. SILTY SAND WITH GRAVEL (SM); very dense, dry, light brown; fine to coarse sand; fine to coarse, rounded to subangular gravel. Pleistocene Continental Glacial Till (Qgt) SILTY GRAVEL WITH SAND (GM); very dense, slightlymoist, gray; fine to coarse sand; fine to coarse; rounded tosubangular gravel; few cobbles; hardpan. Bottom of exploration at 4 ft. bgs.S1Operator Work Start/Completion Dates Blows/footWater Content (%) Equipment Legend Contractor 394 393 392 391 390 389 388 387 386 ATP-11 Tests ZAXIS 85USB Backhoe or trackhoe High Meadows Excavation Exploration Method(s) See Exploration Log Key for explanationof symbols SampleType/ID Depth to Water (Below GS) Description NA Grab sample No Water Encountered Ground Surface Elev. (NAVD88) Exploration Notes andCompletion Details Blows/6" Coordinates (Lat,Lon WGS84) Grab Logged by: MRHApproved by: EOA Top of Casing Elev. (NAVD88) 1 2 3 4 5 6 7 8 9 8/29/2023 Project Address & Site Specific Location 395' (est) Plastic Limit 48.0216, -122.8216 (est)ATP-11 Depth(feet)MaterialType Andrew Monsaas SampleTypeElev.(feet) No Water Encountered Liquid Limit Geotechnical Exploration Log 1 2 3 4 5 6 7 8 9 63 4 Corners Rd, Port Townsend, See Figure 2. ExplorationLog Exploration Number WaterLevelSheet 1 of 1 Depth(ft) Sampling Method NEW STANDARD EXPLORATION LOG TEMPLATE P:\GINTW\PROJECTS\210421 - OLYMPIC DISCOVERY TRAIL.GPJ October 30, 2023Olympic Discovery Trail - 210421 10 20 30 400 50 APPENDIX B Geotechnical Laboratory Analysis Results ASPECT CONSULTING PROJECT NO. 210421  DECEMBER 21, 2023 FINAL B-1 B. Geotechnical Laboratory Analysis Results Aspect subcontracted Hayre McElroy and Associates, LLC to conduct laboratory tests on selected soil samples to characterize certain engineering (physical) properties of the Site soils. Laboratory testing included determination of natural moisture content, Atterberg Limits, grain-size distribution, and fines content in accordance with ASTM test methods D2216, D4318, D6913, and D1140. The results of the laboratory tests are presented in this appendix; moisture content and Atterberg Limit results are also presented graphically on the boring logs in Appendix A. The results of the grain-size distribution tests are presented as curves in this appendix, plotting percent finer by weight versus grain size. APPENDIX C Pilot Infiltration Testing ASPECT CONSULTING PROJECT NO. 210421  DECEMBER 21, 2023 FINAL C-1 C. Pilot Infiltration Testing Aspect completed one pilot infiltration tests (PIT) on August 29, 2023, following methods for small-scale PITs as described in the Stormwater Management Manual for Western Washington (Ecology, 2019). The purpose of these PITs was to provide design infiltration rates for proposed stormwater infiltration and permeable pavement design for the Project. C.1 Methodology A pit measuring approximately 5.8 feet by 7 feet (APIT-03) was excavated to approximately 6 feet bgs. Water was supplied from a faucet and conveyed to the pit via a 0.75-inch-diameter hose. A totalizer was equipped to the hydrant to monitor flowrate and total volume discharged. Pressure transducers were placed within the base of the pit to record the depth of water every 60 seconds for the duration of the test. At the start of the test, the discharged flow rate was adjusted using gate-valves until the pit was able to maintain a constant head greater than 1 foot of water. After the pit had been soaking in more than 1 foot of water for approximately 6 hours, water was added for 1 hour to maintain a constant head, then the pits were allowed to freely drain. C.2 Results The infiltration test results are shown on the table and figure below. Infiltration rates were calculated in two different ways: • The first was the constant head test, where a constant water level was maintained for a span of 1 hour near the end of each test. An infiltration rate was calculated by measuring the volume of water infiltrating into the pit in an approximate 1- hour span and dividing by the area of the bottom of each pit. • The second method of infiltration rate calculation was the falling head test. To calculate infiltration rates with this method, the change in water level in the first hour after the water was shut off in each pit. Aspect calculated the design infiltration rate using equations from the SMMWW and the results from the constant head test in the PIT. The following table shows the key correction factors and calculations for the design infiltration rate in the PIT. The results show an infiltration rate of 0.3 inches per hour based on the falling head test. ASPECT CONSULTING C-2 FINAL PROJECT NO. 210421  DECEMBER 21, 2023 PIT-03 Falling Head Test Parameters APIT-03 PIT Head (inches) 3.9 Elapsed Time (hours) 5.1 Measured Infiltration Rate (in/hr) 0.8 Infiltration Correction Factors Site Variability Factor 0.75 Test Method Factor 0.5 Long-Term Plugging Factor 0.9 Design Infiltration Results Design Infiltration Rate (in/hr) 0.3 Notes: The geometry correction factor assumes 5 ft depth to water and facility width of 100 ft Pilot Infiltration Test Methods are based on the Stormwater Management Manual for Western Washington APPENDIX D Report Limitations and Guidelines for Use ASPECT CONSULTING REPORT LIMITATIONS AND GUIDELINES FOR USE Geoscience is Not Exact The geoscience practices (geotechnical engineering, geology, and environmental science) are far less exact than other engineering and natural science disciplines. It is important to recognize this limitation in evaluating the content of the report. If you are unclear how these "Report Limitations and Guidelines for Use" apply to your project or property, you should contact Aspect Consulting (Aspect). This Report and Project-Specific Factors Aspect’s services are designed to meet the specific needs of our clients. Aspect has performed the services in general accordance with our agreement (the Agreement) with the Client (defined under the Limitations section of this project’s work product). This report has been prepared for the exclusive use of the Client. This report should not be applied for any purpose or project except the purpose described in the Agreement. Aspect considered many unique, project-specific factors when establishing the Scope of Work for this project and report. You should not rely on this report if it was: • Not prepared for you; • Not prepared for the specific purpose identified in the Agreement; • Not prepared for the specific subject property assessed; or • Completed before important changes occurred concerning the subject property, project, or governmental regulatory actions. If changes are made to the project or subject property after the date of this report, Aspect should be retained to assess the impact of the changes with respect to the conclusions contained in the report. Reliance Conditions for Third Parties This report was prepared for the exclusive use of the Client. No other party may rely on the product of our services unless we agree in advance to such reliance in writing. This is to provide our firm with reasonable protection against liability claims by third parties with whom there would otherwise be no contractual limitations. Within the limitations of scope, schedule, and budget, our services have been executed in accordance with our Agreement with the Client and recognized geoscience practices in the same locality and involving similar conditions at the time this report was prepared Property Conditions Change Over Time This report is based on conditions that existed at the time the study was performed. The findings and conclusions of this report may be affected by the passage of time, by events such as a change in property use or occupancy, or by natural events, such as floods, ASPECT CONSULTING earthquakes, slope instability, or groundwater fluctuations. If any of the described events may have occurred following the issuance of the report, you should contact Aspect so that we may evaluate whether changed conditions affect the continued reliability or applicability of our conclusions and recommendations. Geotechnical, Geologic, and Environmental Reports Are Not Interchangeable The equipment, techniques, and personnel used to perform a geotechnical or geologic study differ significantly from those used to perform an environmental study and vice versa. For that reason, a geotechnical engineering or geologic report does not usually address any environmental findings, conclusions, or recommendations (e.g., about the likelihood of encountering underground storage tanks or regulated contaminants). Similarly, environmental reports are not used to address geotechnical or geologic concerns regarding the subject property. We appreciate the opportunity to perform these services. If you have any questions, please contact the Aspect Project Manager for this project.