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HomeMy WebLinkAbout005 Geotech Report Geotechnical Engineering Report Proposed Residence and Shop 155 Night Owl Road Port Townsend, WA Mr. Charles Southard 8087 Lars Drive NE Bremerton, WA 98311 Prepared For: July 8, 2022 Project No. 22-0512 Mr. Charles Southard 8087 Lars Drive NE Bremerton, WA 98311 Regarding: Geotechnical Engineering Report Proposed Residence and Shop 155 Night Owl Road Port Townsend, WA Dear Mr. Southard, As requested, GeoTest Services, Inc. [GeoTest] is pleased to submit the following report summarizing the results of our geotechnical evaluation for the proposed residence and shop located at 155 Night Owl Road in Port Townsend, WA (see Vicinity Map, Figure 1). This report has been prepared in general accordance with the terms and conditions established in our services agreement dated May 16, 2022 and authorized by yourself. We appreciate the opportunity to provide geotechnical services on this project and look forward to assisting you during the construction phase. Should you have any further questions regarding the information contained within the report, or if we may be of service in other regards, please contact the undersigned. Respectfully, GeoTest Services, Inc. Coire McCabe, LG Staff Geologist Tristan Coragiulo, G.I.T. Geotechnical Project Manager Edwardo Garcia, P.E. Geotechnical Department Manager Enclosure: Geotechnical Engineering Report TABLE OF CONTENTS PURPOSE AND SCOPE OF SERVICES ........................................................................................ 1 PROJECT DESCRIPTION ........................................................................................................... 1 Surface Conditions ...................................................................................................................... 2 Subsurface Soil Conditions .......................................................................................................... 3 General Geologic Conditions ...................................................................................................... 5 Groundwater ............................................................................................................................... 5 Web Soil Survey .......................................................................................................................... 5 GEOLOGIC HAZARDS .............................................................................................................. 6 Erosion Hazard Areas .................................................................................................................. 6 Seismic Hazard Areas .................................................................................................................. 7 CONCLUSIONS AND RECOMMENDATIONS .............................................................................. 8 Site Preparation and Earthwork ................................................................................................. 8 Fill and Compaction .................................................................................................................... 9 Reuse of On-Site Soil ............................................................................................................... 9 Imported Structural Fill ......................................................................................................... 10 Backfill and Compaction ....................................................................................................... 10 Wet Weather Earthwork ........................................................................................................... 10 Seismic Design Considerations ................................................................................................. 11 Foundation Support .................................................................................................................. 11 Allowable Bearing Capacity .................................................................................................. 12 Foundation Settlement ......................................................................................................... 12 Floor Support ............................................................................................................................ 12 Foundation and Site Drainage .................................................................................................. 13 Resistance to Lateral Loads ....................................................................................................... 14 Temporary and Permanent Slopes ........................................................................................... 15 Utilities ...................................................................................................................................... 15 Dewatering Considerations .................................................................................................. 16 Stormwater Infiltration Potential ............................................................................................. 16 Geotechnical Consultation and Construction Monitoring ........................................................ 17 USE OF THIS REPORT ............................................................................................................ 18 REFERENCES ......................................................................................................................... 18 GeoTest Services, Inc. Proposed Residence and Shop, Port Townsend, WA 1 July 8, 2022 Project Number: 22-0512 PURPOSE AND SCOPE OF SERVICES The purpose of this evaluation is to obtain subsurface information at the project site that will be used in the design of the above referenced project. Our final product will be a suitably illustrated report containing a summary of site conditions pertaining to project design and construction. The purpose of this evaluation is to establish general subsurface conditions beneath the site from which conclusions and recommendations pertaining to project design can be formulated. Our scope of services includes the following tasks:  Exploration of soil and groundwater conditions underlying the site by excavating test pits with a subcontracted excavator to evaluate subsurface conditions (TP-1 – TP-4). GeoTest also advanced four Dynamic Cone Penetrometers (DCPs) on the project site (DCP-1 – DCP- 4).  Laboratory testing on representative samples to classify and evaluate the engineering characteristics of the soils encountered.  To provide a written report containing a description of subsurface conditions, exploration logs, laboratory determinations of soil classification and engineering properties, surface and subsurface groundwater conditions, findings and recommendations pertaining to site preparation and earthwork, fill and compaction, seismic design, foundation recommendations, foundation and site drainage, utilities, stormwater infiltration and treatment, geotechnical consultation, and/or construction monitoring. • Assess Geologically Hazardous Areas (if present) per Jefferson County Code (JCC). PROJECT DESCRIPTION The relatively level subject parcel is situated approximately 750 feet south of Four Corners Road on Night Owl Road in Port Townsend, WA (Parcel No. 001334021, 10.31 acres). GeoTest understands that a single-family residence and shop will be constructed on the western- central portion of the subject parcel. GeoTest does not have a formalized site development plan, but it is expected that the property will be developed with the proposed residence having a round building footprint of approximately 962 square feet, with the shop having a footprint of 1,400 square feet just west of the proposed residence. The proposed building is expected to use wood- framed construction with shallow conventional foundations and slab on grade floors. GeoTest anticipates that some form of mitigation against liquefaction-induced settlements will be needed as part of structural design services. There is a known regional liquefaction potential that exists in the vicinity of the planned construction. GeoTest Services, Inc. Proposed Residence and Shop, Port Townsend, WA 2 July 8, 2022 Project Number: 22-0512 GeoTest understands that stormwater management may include the use of infiltration facilities distributed across the perimeter of the subject site. GeoTest was not provided with a plan sheet showing any formal or preliminary stormwater design concepts; it should generally be expected that additional input and/or involvement may be required after the submission of this report. SITE CONDITIONS This section includes a description of the general surface and subsurface conditions observed at the project site during the time of our field investigation. Interpretations of site conditions are based on the results and review of available information, site reconnaissance, subsurface explorations, laboratory testing, and previous experience in the project vicinity. Surface Conditions The proposed area of development includes a fenced and gated 10-acre property that has been mostly cleared of vegetation. The parcel is vacant except for some scattered out-buildings and farming equipment. Numerous brush piles and dirt paths were observed on site. A gravel driveway runs along the west side of the lot, with a dirt road accessing the parcel from the southwest and the north. The proposed building site is relatively level, covered with grass, and contains a few tall trees distributed around the perimeter of the property. Image 1. A screenshot taken from Jefferson County GIS Portal, showing aerial view of the subject parcel. GeoTest Services, Inc. Proposed Residence and Shop, Port Townsend, WA 3 July 8, 2022 Project Number: 22-0512 With less than a few feet of elevation differential across the property, the planned improvements are expected to require minor grading. GeoTest does not expect that more than a few feet of cut or fill will be required to achieve the desired finished grades. Some trees along the western perimeter of the subject parcels may be removed in order to construct the proposed structure. In general, the subject parcel is surrounded by rural residential homes and similar 10-acre properties. GeoTest observed a few preexisting out-buildings, old barn structures, and garden beds around the lot. Image 2. Site conditions showing the northwest corner of the site as well as the parcel’s relatively flat topography and clearing remnants. Image taken facing south (Images 2 and 3 taken on June 7, 2022). Subsurface Soil Conditions Subsurface conditions were explored by advancing four test pits and DCPs on June 7, 2022 (TP-1 – TP-4 and DCP-1 – DCP-4). Our test pit explorations were advanced to depths ranging between 10 and 11 feet below the ground surface (BGS) using an excavator, while the DCPs reached refusal between 3.5 and 5 feet BGS. Approximate locations of these explorations have been plotted on the Site and Exploration Plan (Figure 2). DCP tests were conducted to evaluate the relative density and/or consistency of the site soils. The DCP analyses consisted of driving an approximately 1-inch diameter steel rod into the ground utilizing a 35-pound drop hammer. By measuring the number of blows it takes to drive the rod every four inches (10 cm), the general density of granular soils and the stiffness of cohesive soils can be determined. The number of blows for each increment can be correlated to standard N values typically obtained from Standard Penetration Testing (SPT) performed using a mechanized soil drill rig. DCPs were advanced to depths of between 3.5 and 5 feet BGS or until refusal was reached (50 blow per 4 inches). GeoTest Services, Inc. Proposed Residence and Shop, Port Townsend, WA 4 July 8, 2022 Project Number: 22-0512 The on-site subsurface soils generally consisted of about 0.5 to 1-foot of medium stiff, brown to black, silts with appreciable organics that were interpreted to be topsoil. Underlying the topsoil, GeoTest observed medium stiff to very stiff, gray-brown, sandy silt with generally low gravel contents. Between 2.5 and 8 feet BGS, GeoTest observed a sharp geologic contact which exhibited medium dense, brown, sandy, poorly graded gravel underlying the silt. GeoTest interpreted both the silt and the poorly graded gravels on site as Outwash. See the Site and Exploration Plan (Figure 2) attached at the end of this report for the approximate locations of our explorations. Image 3. Subsurface conditions within TP-4 (southernmost exploration), with 2.5 feet of topsoil and sandy silts overlying medium dense, poorly graded, sandy gravels. GeoTest Services, Inc. Proposed Residence and Shop, Port Townsend, WA 5 July 8, 2022 Project Number: 22-0512 General Geologic Conditions Geologic information for the project site was obtained from the Geologic Map of the Port Townsend South and Part of the Port Townsend North 7.5-minute Quadrangles, Jefferson County, Washington (Schasse, H.W. and Slaughter, S.L., 2005), published by the Washington State Department of Natural Resources. According to the referenced map, subsurface soils in the vicinity of the project site consist of the subunit of Recessional Outwash (Qgo) from the Continental Glacial Drift, deposited during the Fraser glaciation event. The Recessional Outwash generally consists of pebble to cobble gravel and sand, generally unoxidized unless in contact with groundwater, planar to cross-bedded, with localized areas of silt and clay. Native soils encountered during our subsurface explorations were generally consistent with the mapped deposits. For the purposes of this report, GeoTest will refer to both the silts/clays and sandy gravels as “Outwash.” Groundwater Groundwater was not encountered at the time of our explorations. The groundwater conditions reported on the exploration logs are for the specific locations and dates indicated, and therefore may not be indicative of other locations and/or times. Groundwater levels are variable and groundwater conditions will fluctuate depending on local subsurface conditions, precipitation, and changes in on-site and off-site use. Seasonal groundwater monitoring is not currently part of our scope of services, and it should be expected that additional efforts may be needed to establish seasonal groundwater highs for the project site. Web Soil Survey According to the United States Department of Agriculture (USDA) Natural Resource Conservation Service (NRCS) Web Soil Survey website, one relevant soil unit is present on the subject property. Please reference Table 1 below for general characteristics. Based on the erosion “K” factor assigned to this soil unit by the NRCS, the soils present on-site present a moderate erosion potential. Values of the erosion factor “K” range from 0.02 to 0.69; the higher the value, the more susceptible the soil is to sheet and rill erosion by water. GeoTest Services, Inc. Proposed Residence and Shop, Port Townsend, WA 6 July 8, 2022 Project Number: 22-0512 GEOLOGIC HAZARDS Jefferson County Code (JCC) 18.22.510 refers to Washington Administrative Code (WAC) 365- 190-030(9) for “geologically hazardous areas,” which are defined as “areas that because of their susceptibility to erosion, sliding (landslide), earthquake, or other geological events, are not suited to siting commercial, residential, or industrial development consistent with public health or safety concerns” The proposed development area, subject property, and surrounding areas are relatively flat with little to no discernable elevation change. Thus, there does not appear to be the potential for landslide hazards on the property, as defined by JCC 18.10.120, JCC 18.22.510(1b), and the WAC 365-190-030(10). Thus, it is also GeoTest’s opinion that no mitigation is needed for potential landslide hazards. Erosion Hazard Areas JCC 18.22.510(1a) and WAC 365-190-030(5) define Erosion Hazard Areas as “areas containing soils which, according to the United States Department of Agriculture Natural Resources Conservation Service Soil Survey Program, may experience significant erosion. Erosion hazard areas also include coastal erosion-prone areas and channel migration zones.” Based on the Web Soil Survey, the subject property can be classified as an Erosion Hazard Area, per JCC 18.22.510(1a). However, because the site is flat, it is our opinion that the erosion Table 1 USDA NRCS Soil Classifications Map Unit Symbol AgB Map Unit Name Agnew silt loam, 0 to 8 percent slopes Soil Description Silt loam, silty clay loam, and stratified sandy loam to gravelly silty clay loam Landform Terraces Parent Material Glaciomarine Deposits Land Capability Classification 3w Erosion K Factor, Whole Soil 0.32 GeoTest Services, Inc. Proposed Residence and Shop, Port Townsend, WA 7 July 8, 2022 Project Number: 22-0512 potential of the site is relatively low. Thus, it is our opinion that no mitigation for Erosion Hazard Areas is needed for this project. Seismic Hazard Areas Seismic Hazard Areas are defined by JCC 18.22.510(1c) and 365-190-030(18) as “areas subject to severe risk of damage as a result of earthquake induced ground shaking, slope failure, settlement, soil liquefaction, debris flows, lahars, or tsunamis.” These areas are typically underlain by soft or loose, granular, saturated soils, have a shallow groundwater table, and are typically located on the floors of river valleys. The site is underlain by Outwash consisting of medium stiff to stiff silts and underlying medium dense gravels. GeoTest did not observe groundwater seepage within our explorations at the time of our investigation and our DCP explorations reached a maximum depth of 5 feet BGS before reaching refusal in medium dense, very gravelly soil conditions. The Outwash on site is also classified as Site Class D according to ASCE 7-16. For these reasons, it is our opinion that the potential for Seismic Hazard Areas on the property is relatively low. Thus, no mitigation for seismic hazards is required for this project. It is also worth noting that the subject property is mapped as having a low potential for seismic liquefaction and does not exist near any active faults or folds, according to the Geologic Information Portal. However, this map only provides an estimate of the likelihood that soil will liquefy because of earthquake shaking and is meant as a general guide to delineate areas prone to liquefaction. Based on the existing site conditions, proposed construction, as well as our local experience in the area, it is GeoTest’s opinion that there is a low probability of liquefaction occurring beneath the subject site during a design level earthquake. Image 4. Screenshot from the DNR Geologic Information Portal, in which the entire project site is considered to possess a low liquefaction susceptibly (light yellow). Project Site GeoTest Services, Inc. Proposed Residence and Shop, Port Townsend, WA 8 July 8, 2022 Project Number: 22-0512 CONCLUSIONS AND RECOMMENDATIONS Based on the evaluation of the data collected during this investigation, it is our opinion that the subsurface conditions at the site are suitable for the proposed development, provided the recommendations contained herein are incorporated into the project design. As previously mentioned, the site is relatively level and underlain by medium stiff to stiff silts and medium dense, sandy gravels typical of Outwash deposits. We recommend the client plan for a typical stripping depth of 1 foot for building footprints, and ancillary driveway and pavement structures. The Outwash was typically encountered within 1 foot of predeveloped site grades and is suitable for shallow conventional foundation support when recompacted to a firm and unyielding condition. If encountered, existing fill, deleterious materials, organics, and loose/unsuitable portions of native soil (if remedial compaction is infeasible) should be removed and replaced with suitable Structural Fill. The native Outwash sands and gravels may be suitable for reuse as Structural Fill when placed and compacted as recommended in this report. Shallow restriction layers exist on the property that will make the design of infiltration systems challenging. It should also be noted that silts and clays were encountered as deep as 8 feet BGS in the northern most test pit at the time of our investigation. The Stormwater Manual for Western Washington (Manual) has requirements and limitations for the design of stormwater facilities when shallow restriction layers exist below a facility. Stormwater management strategies that include elements of Low Impact Development (LID) may be feasible but should have a fundamental expectation that there will be shallow restriction layers present that might influence the overall design of stormwater systems. At the time of writing this report, it is our understanding that either dry wells or dispersion systems are being considered for facilities. It should be noted that seasonal groundwater monitoring and pilot infiltration testing are outside the scope of this report and may be required by Jefferson County. GeoTest is able to provide these services upon request. It should also be noted that a site development plan showing the building type, footprint, or stormwater facilities was not available to us at the time of writing this report. Thus, it must be expected that additional design services, possibly paired with additional field work and collaboration with the project Civil Engineer, will be needed to complete the stormwater design. Site Preparation and Earthwork The portions of the site proposed for foundation(s), floor slabs, and/or sidewalks development should be prepared by removing topsoil, deleterious material, and significant accumulations of organics. Based on our explorations, GeoTest anticipates 0.5 to 1 feet of removal to expose mineral soil. Prior to placement of any foundation elements or Structural Fill, the exposed GeoTest Services, Inc. Proposed Residence and Shop, Port Townsend, WA 9 July 8, 2022 Project Number: 22-0512 subgrade under all areas to be occupied by soil-supported floor slabs, spread, or continuous foundations should be recompacted to a firm and unyielding condition. Verification of compaction can be accomplished through proof rolling with a loaded dump truck, large self- propelled vibrating roller, or similar piece of equipment applicable to the size of the excavation. The purpose of this effort is to identify loose or soft soil deposits so that, if feasible, the soil distributed during site work can be recompacted. Proof rolling should be carefully observed by qualified geotechnical personnel. Areas exhibiting significant deflection, pumping, or over-saturation that cannot be readily compacted should be overexcavated to firm soil. Alternatively, Dynamic Cone Penetrometers or soil probing by a qualified GeoTest representative can confirm firm and unyielding conditions if a proof roll cannot be performed. Overexcavated areas should be backfilled with compacted granular material placed in accordance with subsequent recommendations for Structural Fill. During periods of wet weather, proof rolling could damage the exposed subgrade. Under these conditions, qualified geotechnical personnel should observe subgrade conditions to determine if proof rolling is feasible. Fill and Compaction Structural Fill used to obtain final elevations for footings and soil-supported floor slabs must be properly placed and compacted. In most cases, suitable, non-organic, predominantly granular soil may be used for fill material provided the material is properly moisture conditioned prior to placement and compaction, and the specified degree of compaction is obtained. Material containing topsoil, wood, trash, organic material, or construction debris is not suitable for reuse as Structural FIll and should be properly disposed off-site or placed in nonstructural areas. Soils containing more than approximately 5 percent fines are considered moisture sensitive and are difficult to compact to a firm and unyielding condition when over the optimum moisture content by more than approximately 2 percent. The optimum moisture content is that which allows the greatest dry density to be achieved at a given level of compactive effort. Reuse of On-Site Soil Due to excessive silt content of the near surface silts, these native silts are not recommended for use as Structural Fill due to the difficulties associated with moisture conditioning fine-grained soil types. GeoTest recommends any reuse of the native silt soils be limited to landscape and other non-structural areas. The native Outwash gravel is suitable for reuse as Structural Fill when placed at or near optimum moisture contents, as determined by ASTM D1557 and if allowed for in the project plans and specifications. GeoTest Services, Inc. Proposed Residence and Shop, Port Townsend, WA 10 July 8, 2022 Project Number: 22-0512 Imported Structural Fill GeoTest recommends that imported Structural Fill consist of clean, well-graded sandy gravel, gravelly sand, or other approved naturally occurring granular material (pit run) with at least 30 percent retained on the No. 4 sieve, or a well-graded crushed rock. Structural Fill for dry weather construction may contain up to 10 percent fines (that portion passing the U.S. No. 200 sieve) based on the portion passing the U.S. No. 4 sieve. The use of an imported fill having more than 10 percent fines may be feasible, but the use of these soils should generally be reviewed by the design team prior to the start of construction. Imported Structural Fill with less than 5 percent fines should be used during wet weather conditions. Due to wet site conditions, soil moisture contents could be high enough that it may be difficult to compact even clean imported select granular fill to a firm and unyielding condition. Soils with an over-optimum moisture content should be scarified and dried back to a suitable moisture content during periods of dry weather or removed and replaced with drier Structural Fill. Backfill and Compaction Structural Fill should be placed in horizontal lifts. The Structural Fill must measure 8 to 10 inches in loose thickness and be thoroughly compacted. All Structural Fill placed under load bearing areas should be compacted to at least 95 percent of the maximum dry density, as determined using test method ASTM D1557. The top of the compacted Structural Fill should extend outside all foundations and other structural improvements a minimum distance equal to the thickness of the fill. We recommend that compaction be tested after placement of each lift in the fill pad. Wet Weather Earthwork The upper, native soils on site have a significant percentage of fines content. As such, these soils may be susceptible to degradation during wet weather. If construction takes place during wet weather, GeoTest recommends that Structural Fill consist of imported, clean, well-graded sand or sand and gravel as described above. If fill is to be placed or earthwork is to be performed in wet conditions, the contractor may reduce soil disturbance by:  Limiting the size of areas that are stripped of topsoil and left exposed  Accomplishing earthwork in small sections  Limiting construction traffic over unprotected soil  Sloping excavated surfaces to promote runoff  Limiting the size and type of construction equipment used  Providing gravel ‘working mats’ over areas of prepared subgrade  Removing wet surficial soil prior to commencing fill placement each day GeoTest Services, Inc. Proposed Residence and Shop, Port Townsend, WA 11 July 8, 2022 Project Number: 22-0512  Sealing the exposed ground surface by rolling with a smooth drum compactor or rubber- tired roller at the end of each working day  Providing up-gradient perimeter ditches or low earthen berms and using temporary sumps to collect runoff and prevent water from ponding and damaging exposed subgrades Seismic Design Considerations The Pacific Northwest is seismically active, and the site could be subject to movement from a moderate or major earthquake. Consequently, moderate levels of seismic shaking should be accounted for during the design life of the project, and the proposed structure should be designed to resist earthquake loading using appropriate design methodology. For structures designed using the seismic design provisions of the 2018 International Building Code, the Outwash is classified as Site Class D according to ASCE 7-16. The structural engineer should select the appropriate design response spectrum based on Site Class D soil and the geographical location of the proposed construction. Foundation Support Continuous or isolated spread footings founded on proof-rolled, undisturbed, medium dense/stiff native soils or on properly compacted Structural Fill placed directly over undisturbed native soil can provide foundation support for the proposed improvements. We recommend that qualified geotechnical personnel confirm that suitable bearing conditions have been reached prior to placement of Structural Fill or foundation formwork. To provide proper support, GeoTest recommends that existing topsoil, existing fill, and/or loose/soft upper portions of the native soil be removed from beneath the building foundation area(s) or be replaced with properly compacted Structural Fill as described in the Fill and Compaction section of this report. Localized overexcavation, if necessary, can be backfilled to the design footing elevation with lean concrete, or foundations may be extended to bear on undisturbed native soil. In areas requiring overexcavation to competent native soil, the limits of the overexcavation should extend laterally beyond the edge of each side of the footing a distance equal to the depth of the excavation below the base of the footing. If lean concrete is used to backfill the overexcavation, the limits of the overexcavation need only extend a nominal distance beyond the width of the footing. In addition, GeoTest recommends that foundation elements for the proposed structure(s) bear entirely on similar soil conditions to help prevent differential settlement from occurring. Continuous and isolated spread footings should be founded 18 inches, minimum, below the lowest adjacent final grade for freeze/thaw protection. The footings should be sized in accordance with the structural engineer’s prescribed design criteria and seismic considerations. GeoTest Services, Inc. Proposed Residence and Shop, Port Townsend, WA 12 July 8, 2022 Project Number: 22-0512 Allowable Bearing Capacity Assuming the above foundation support criteria are satisfied, continuous or isolated spread footings founded directly on properly prepared native soils or on compacted Structural Fill placed directly over undisturbed native soils may be proportioned using a net allowable soil bearing pressure of 2,000 pounds per square foot (psf). The "net allowable bearing pressure" refers to the pressure that can be imposed on the soil at foundation level. This pressure includes all dead loads, live loads, the weight of the footing, and any backfill placed above the footing. The net allowable bearing pressure may be increased by one-third for transient wind or seismic loads. Foundation Settlement Settlement of shallow foundations depends on foundation size and bearing pressure, as well as the strength and compressibility characteristics of the underlying soil. If construction is accomplished as recommended and at the maximum allowable soil bearing pressure, GeoTest estimates the total settlement of building foundations to be less than one inch under static conditions. Differential settlement between two adjacent load-bearing components supported on competent soil is estimated to be less than one half the total settlement. Floor Support Conventional slab-on-grade floor construction is feasible for the planned site improvements. Floor slabs may be supported on properly prepared native subgrade or on properly placed and compacted Structural Fill placed over properly prepared native soil. Prior to placement of the Structural Fill, the native soil should be proof rolled as recommended in the Site Preparation and Earthwork section of this report. GeoTest recommends that interior concrete slab-on-grade floors be underlain with at least 6 inches of clean, compacted, free-draining crushed gravel to serve as a capillary break. This material should be clear, crushed, ¾-inch rock with no fines or similar. The purpose of this gravel layer is to provide uniform support for the slab, provide a capillary break, and act as a drainage layer. To help reduce the potential for water vapor migration through floor slabs, a continuous 10- to 15-mil minimum thick polyethylene sheet with tape-sealed joints should be installed below the slab to serve as an impermeable vapor barrier. The vapor barrier should be installed and sealed in accordance with the manufacturer’s instructions. American Concrete Institute (ACI) guidelines suggest that the slab may be poured directly on the vapor barrier. A Subgrade Modulus (k) of 150 pounds per cubic inch (pci) is recommended for use in design of concrete slab elements placed on near-surface soils remedially compacted to Structural Fill requirements. GeoTest Services, Inc. Proposed Residence and Shop, Port Townsend, WA 13 July 8, 2022 Project Number: 22-0512 Exterior concrete slabs-on-grade, such as for parking and sidewalks, may be supported directly on properly prepared existing site soils. However, long-term performance will be enhanced if exterior slabs are placed on a layer of clean, durable, well-draining granular material above existing site soils. Foundation and Site Drainage Positive surface gradients should be provided adjacent to the proposed building to direct surface water away from the building and toward suitable drainage facilities. Roof drainage should not be introduced into the perimeter footing drains but should be separately discharged directly to the stormwater collection system or similar municipality-approved outlet. Pavement and sidewalk areas, if present, should be sloped and drainage gradients should be maintained to carry surface water away from the building towards an approved stormwater collection system. Surface water should not be allowed to pond and soak into the ground surface near buildings or paved areas during or after construction. Construction excavations should be sloped to drain to sumps where water from seepage, rainfall, and runoff can be collected and pumped to a suitable discharge facility. The filtering media may consist of open-graded drain rock wrapped in a nonwoven geotextile fabric such as Mirafi 140N (or equivalent) or wrapped with a graded sand and gravel filter. For foundations supporting retaining walls, drainage backfill should be carried up the back of the wall and be at least 12 inches wide. The drainage backfill should extend from the foundation drain to within approximately 1 foot of the finished grade and consist of open-graded drain rock containing less than 3 percent fines by weight passing the U.S. Standard No. 200 sieve (based on a wet sieve analysis of that portion passing the U.S. Standard No. 4 sieve). The invert of the footing drainpipe should be placed at approximately the same elevation as the bottom of the footing or 12 inches below the adjacent floor slab grade (whichever is deeper) so that water will be contained. This process prevents water from seeping through walls or floor slabs. The drain system should include cleanouts to allow for periodic maintenance and inspection. The drainage backfill should extend from the foundation drain to within approximately 1 foot of the finished grade and consist of open-graded drain rock containing less than 3 percent fines by weight passing the U.S. Standard No. 200 sieve (based on a wet sieve analysis of that portion passing the U.S. Standard No. 4 sieve). The invert of the footing drainpipe should be placed at approximately the same elevation as the bottom of the footing or 12 inches below the adjacent floor slab grade, whichever is deeper, so that water will be contained. This process prevents water from seeping through walls or floor slabs. The drain system should include cleanouts to allow for periodic maintenance and inspection. Please understand that the above recommendations are intended to assist the design engineer and/or architect in development of foundation and site drainage parameters and are based on GeoTest Services, Inc. Proposed Residence and Shop, Port Townsend, WA 14 July 8, 2022 Project Number: 22-0512 our experience with similar projects in the area. The final foundation and site drainage plan that will be incorporated into the project plans is to be determined by the design team. Resistance to Lateral Loads The lateral earth pressures that develop against foundation walls will depend on the method of backfill placement, degree of compaction, slope of backfill, type of backfill material, provisions for drainage, magnitude and location of any adjacent surcharge loads, and the degree to which the wall can yield laterally during or after placement of backfill. If the wall can rotate or yield so the top of the wall moves an amount equal to or greater than about 0.001 to 0.002 times its height (a yielding wall), the soil pressure exerted comprises the active soil pressure. When a wall is restrained against lateral movement or tilting (a nonyielding wall), the soil pressure exerted comprises the at rest soil pressure. Wall restraint may develop if a rigid structural network is constructed prior to backfilling or if the wall is inherently stiff. GeoTest recommends that yielding walls under drained conditions be designed for an equivalent fluid density of 40 pounds per cubic foot (pcf), for Structural Fill in active soil conditions. Nonyielding walls under drained conditions should be designed for an equivalent fluid density of 60 pcf, for Structural Fill in at-rest conditions. GeoTest should be contacted if the final design includes submerged walls so that we provided updated recommendations. Design of walls should include appropriate lateral pressures caused by surcharge loads located within a horizontal distance equal to or less than the height of the wall. For uniform surcharge pressures, a uniformly distributed lateral pressure equal to 35 percent and 50 percent of the vertical surcharge pressure should be added to the lateral soil pressures for yielding and nonyielding walls, respectively. GeoTest also recommends that a seismic surcharge of 8H be included where H is the wall height. The seismic surcharge should be modeled as a rectangular distribution with the resultant applied at the midpoint of the wall. Passive earth pressures developed against the sides of building foundations, in conjunction with friction developed between the base of the footings and the supporting subgrade, will resist lateral loads transmitted from the structure to its foundation. For design purposes, the passive resistance of well-compacted fill placed against the sides of foundations is equivalent to a fluid with a density of 180 pcf. The recommended value includes a safety factor of about 1.5 and assumes that the ground surface adjacent to the structure is level in the direction of movement for a distance equal to or greater than twice the embedment depth. The recommended value also assumes drained conditions that will prevent the buildup of hydrostatic pressure in the compacted fill. Retaining walls should include a drain system constructed in general accordance with the recommendations presented in the Foundation and Site Drainage section of this report. In design computations, the upper 12 inches of passive resistance should be neglected if the soil is not covered by floor slabs or pavement. If future call for the removal of the soil providing resistance, the passive resistance should not be considered. GeoTest Services, Inc. Proposed Residence and Shop, Port Townsend, WA 15 July 8, 2022 Project Number: 22-0512 An allowable coefficient of base friction of 0.3 for silts and/or 0.35 for granular Outwash or Structural Fill, applied to vertical dead loads only, may be used between the underlying soil and the base of the footing. If passive and frictional resistance are considered together, one half the recommended passive soil resistance value should be used since larger strains are required to mobilize the passive soil resistance as compared to frictional resistance. A safety factor of about 1.5 is included in the base friction design value. GeoTest does not recommend increasing the coefficient of friction to resist seismic or wind loads. Temporary and Permanent Slopes The contractor is responsible for construction slope configurations and maintaining safe working conditions, including temporary excavation stability. All applicable local, state, and federal safety codes should be followed. All open cuts should be monitored during and after excavation for any evidence of instability. If instability is detected, the contractor should flatten the side slopes or install temporary shoring. Temporary excavations in excess of 4 ft should be shored or sloped in accordance with Safety Standards for Construction Work Part N, WAC 296-155-66403. Outwash soils are classified as a Type B soil according to WAC 296-155-66401 and may be sloped as steep as 1:1 (Horizontal: Vertical). All soils encountered are classified as Type C soil in the presence of groundwater seepage and may be sloped as steep as 1.5:1. Flatter slopes or temporary shoring may be required in areas where groundwater flow is present and unstable conditions develop. Temporary slopes and excavations should be protected as soon as possible using appropriate methods to prevent erosion from occurring during periods of wet weather. GeoTest recommends that permanent cut or fill slopes be designed for inclinations of 2H:1V or flatter. Permanent cuts or fills used in detention ponds, retention ponds, or earth slopes intended to hold water should be 3H:1V or flatter. All permanent slopes should be vegetated or otherwise protected to limit the potential for erosion as soon as practical after construction. Utilities Utility trenches must be properly backfilled and compacted to reduce cracking or localized loss of foundation, slab, or pavement support. Excavations for new shallow underground utilities are expected to be placed within Outwash silts and clays in the northern portion of the subject parcel, and Outwash sands and gravels in the southern portion of the subject parcel. Trench backfill in improved areas (beneath structures, pavements, sidewalks, etc.) should consist of Structural Fill as defined in the Fill and Compaction section of this report. Outside of improved areas, trench backfill may consist of reused native material provided the backfill can be compacted to the project specifications. Trench backfill should be placed and compacted in GeoTest Services, Inc. Proposed Residence and Shop, Port Townsend, WA 16 July 8, 2022 Project Number: 22-0512 general accordance with the recommendations presented in the Fill and Compaction section of this report. Surcharge loads on trench support systems due to construction equipment, stockpiled material, and vehicle traffic should be included in the design of any anticipated shoring system. The contractor should implement measures to prevent surface water runoff from entering trenches and excavations. In addition, vibration as a result of construction activity and traffic may cause caving of the trench walls. The contractor is responsible for trench configurations. All applicable local, state, and federal safety codes should be followed. All open cuts should be monitored by the contractor during excavation for any evidence of instability. If instability is detected, the contractor should flatten the side slopes or install temporary shoring. If groundwater or groundwater seepage is present, and the trench is not properly dewatered, the soil within the trench zone may be prone to caving, channeling, and running. Trench widths may be substantially wider than under dewatered conditions. Dewatering Considerations Groundwater was not encountered in our recent explorations. However, based on our previous experience, groundwater elevations seasonally vary and can raise or lower several feet. Typically, groundwater elevations are highest in the late winter and early spring months, and lowest in late summer or early fall. Groundwater elevations vary with season, adjacent site land usage, and recent rainfall. When feasible, GeoTest recommends that utility trenching occur during late summer or early fall, when the water table is at its lowest elevation. It is, however, the Contractor’s responsibility to provide a suitable dewatering plan based on the type and depth of the excavation and the groundwater elevation during construction. Stormwater Infiltration Potential The near surface native soils observed underlying the site contain elevated silt contents and are expected to exhibit low permeability characteristics. The silty Outwash observed within the proposed development area are widely regarded as “hydraulic restriction layers” as defined by the Manual and are used as construction materials in stormwater pond liners and in berm construction where low-permeability soils are required as part of the design. The Manual is the stormwater document currently adopted by Jefferson County, per JCC 18.30.070. Per the Manual, the silty Outwash found on site is expected to have a saturated hydraulic conductivity of less than 0.3 inches per hour, which the Manual defines as a “restriction layer.” GeoTest Services, Inc. Proposed Residence and Shop, Port Townsend, WA 17 July 8, 2022 Project Number: 22-0512 Shallow restriction layers, as defined by the Manual, exist on the property that will make the design of infiltration systems challenging. The Manual has requirements and limitations for the design of stormwater facilities when shallow restriction layers exist below a facility. At the time of this report, a Stormwater Plan has not been developed for this property. Thus, it should be expected that the Civil Engineer will need to review the contents of this report with a specific focus on soil type, soil density, and/or the amount of vertical separation between the bottom of the facility and the restriction layer. Further, GeoTest should be contacted during the preparation of the Stormwater Plan to facilitate a discussion with the designer regarding shallow restriction layers and stormwater management approaches. Stormwater management strategies that include elements of Low Impact Development (LID) may be feasible but should have a fundamental expectation that native soils underlying facilities will consist of low permeability materials. For these reasons, infiltration is expected to be challenging, if not infeasible on this project. It is our understanding that the Civil Engineer is considering the use of dry wells and/or dispersion stormwater systems for this project. Geotechnical Consultation and Construction Monitoring GeoTest recommends that we be involved in the project design review process. The purpose of the review is to verify that the recommendations presented in this report are understood and incorporated in the design and specifications. We also recommend that geotechnical construction monitoring services be provided. These services should include observation by GeoTest personnel during subgrade preparation operations, Structural Fill placement, and compaction efforts to confirm that design subgrade conditions are obtained beneath the areas of improvement. Periodic field density testing should be performed to verify that the appropriate degree of compaction is obtained. The purpose of these services is to observe compliance with the design concepts, specifications, and recommendations of this report. If subsurface conditions differ from those anticipated before the start of construction, GeoTest would be pleased to provide revised recommendations appropriate to the conditions revealed during construction. GeoTest is available to provide a full range of materials testing and special inspection during construction as required by the local building department and the International Building Code. This may include specific construction inspections on materials such as reinforced concrete, reinforced masonry, wood framing, and structural steel. These services are supported by our fully accredited materials testing laboratories. GeoTest Services, Inc. Proposed Residence and Shop, Port Townsend, WA 18 July 8, 2022 Project Number: 22-0512 USE OF THIS REPORT GeoTest has prepared this report for the exclusive use of Mr. Charles Southard and his design consultants for specific application to the design of the proposed residence and shop project located at 155 Night Owl Road in Port Townsend, WA. Use of this report by others is at the user’s sole risk. This report is not applicable to other site locations. Our services are conducted in accordance with accepted practices of the geotechnical engineering profession; no other warranty, express or implied, is made as to the professional advice included in this report. Our site explorations document subsurface conditions at the dates and locations indicated. It is not warranted that these conditions are representative of conditions at other locations and times. The analyses, conclusions, and recommendations contained in this report are based on site conditions to the limited depth and time of our explorations, a geological reconnaissance of the area, and a review of previously published USGS geological information for the site. If variations in subsurface conditions are encountered during construction that differs from those contained within this report, GeoTest should be allowed to review the recommendations and, if necessary, make revisions. If there is a substantial lapse of time between submission of this report and the start of construction, or if conditions change due to construction operations at or adjacent to the project site, we recommend that we review this report to determine the applicability of the conclusions and recommendations contained herein. The earthwork contractor is responsible to perform all work in conformance with all applicable WISHA/OSHA regulations. GeoTest Services, Inc. is not responsible for job site safety on this project, and this responsibility is specifically disclaimed. Attachments: Figure 1 Vicinity Map Figure 2 Site and Exploration Plan Figure 3 Conceptual Footing and Wall Drain Section Figure 4 Soil Classification System and Key Figures 5 – 8 Test Pit Logs Figure 9 Sieve Analysis Test Report Attached Northwest Agricultural Consultants Results Attached Wildcat Dynamic Cone Logs Attached Report Limitations and Guidelines for its Use REFERENCES American Society of Civil Engineers (ASCE). 2017. Minimum Design Loads and Associated Criteria for Buildings and Other Structures. ASCE/SEI 7-16. American Society for Testing and Materials (ASTM). (2012). ASTM D1557-12e1, Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Modified Effort. West Conshohocken, PA: ASTM International. GeoTest Services, Inc. Proposed Residence and Shop, Port Townsend, WA 19 July 8, 2022 Project Number: 22-0512 Gariepy, D., Graul, C., Heye, A., Howie, D., Labib, F., & Song, K. (n.d.), 2019 Stormwater Management Manual for Western Washington (2019 SMMWW) (pp. 1-1108) (United States, Washington State Department of Ecology). International Building Code (IBC), 2018. International Code Council. Jefferson County Code, Jefferson County (Washington). Accessed via http://www.jeffco.us/, in July 2022. Jefferson County, Washington. Jefferson County, WA Public Land Records GIS Portal. Retrieved in July 2022. 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: Washington State Department of Natural Resources, Geologic Map 57, scale 1:24,000. USDA Web Soil Survey. Retrieved July 2022 from https://websoilsurvey.sc.egov.usda.gov/App/WebSoilSurvey.aspx. Washington Administrative Code (WAC), Washington State Legislature, Washington State. Accessed via http://app.leg.wa.gov/WAC/default.aspx, Retrieved in July 2022. Washington Interactive Geologic Map. Washington State Department of Natural Resources - Online Web Services. Retrieved in July 2022. Date:Scale: Figure By:Project PROPOSED SHOP AND RESIDENCE 155NIGHT OWL ROAD PORT TOWNSEND,WASHINGTON 22-0512 1 6-8-2022 CM As Shown VICINITY MAP Date:Scale: Figure By:Project PROPOSED SHOP AND RESIDENCE 155NIGHT OWL ROAD PORT TOWNSEND,WASHINGTON 22-0512 2 6-8-2022 CM As Shown SITE AND EXPLORATION PLAN TP-1 TP-3 TP-2 TP-4 DCP-1 DCP-2 DCP-3 DCP-4 Notes: 1) Aerial Image, georeferencing, and parcel shapefile sourced from the Jefferson County GIS Map Portal 2) Subject Parcel outlined in RED TP-# = Approximate Test Pit Location = Approximate Dynamic Cone Penetrometer Location DCP-# Date:Scale: Figure By:Project PROPOSED RESIDENCE AND SHOP 155NIGHT OWL ROAD PORT TOWNSEND,WASHINGTON 22-0512 3 CONCEPTUAL FOOTING & WALL DRAIN SECTION None6-14-2022 CM Notes: Footings should be properly buried for frost protection in accordance with International Building Code or local building codes (Typically 18 inches below exterior finished grades). This figure is not intended to be representative of a design. This figure is intended to present concepts that can be incorporated into a functional foundation drain designed by a Civil Engineer. In all cases, refer to the Civil plan sheet for drain details and elevations. CONCEPTUAL FOOTINGS WITH INTERIOR SLAB-ON-GRADE Slope to drain away from structure. Floor Slab Suitable Soil Suitable Soil Free Draining Sand and Gravel Fill Coarse Gravel Capillary Break (6 inch minimum, typically clear crushed) Four Inch Diameter, Perforated, Rigid PVC Pipe (Perforations oriented down, wrapped in non-woven geotextile filter fabric, directed to suitable discharge) Drainage Material (Drain Rock or Clear Crushed Rock w/ no fines) Approved Non-woven Geotextile Filter Fabric (18 inch minimum fabric lap) Compacted Low-Permeability Soil (12 inch minimum) or Pavement (2 inch minimum) Appropriate Waterproofing Applied to Exterior of Wall Vapor Barrier Typical Framing 0 1 2 3 4 5 6 7 8 9 10 11 1 2 3 4 5 6 d d d d d d GT W = 5GS OL ML GP-GM GP Medium stiff to very stiff, dark brown-red, moist, low plasticityORGANIC SILTS (Hog Fuel/Topsoil) Stiff, tan, moist, sandy SILT, trace gravel, scattered organics, wood (Outwash) Medium dense, gray-brown, moist, very sandy, poorly graded GRAVEL with silt, trace organics, roots (Outwash) Increased moisture Medium dense, brown, moist, sandy, poorly graded GRAVEL, trace silt, trace cobbles and boulders (Outwash) GeoTest Services, Inc. TEST PIT LOG Test Pit No. TP-1 PROJECT: Southard - Proposed Shop and Residence LOCATION: 155 Night Owl Road, Port Townsend, WA EXPLORATION METHOD: Tracked Excavator CONTRACTOR/DRILLER: Moving Earth LLC PROJECT NO.: 22-0512 DATE: 6/7/2022 ELEVATION: Approx 142' LOGGED BY: CM/JR DEPTH TO WATER TABLE:MA PERCHED WATER:NA CAVING NA Reference Notes:1. Stratigraphic contacts are based on field interpretations and are approximate.2. Reference to the text of this report is necessary for a proper understanding of subsurface conditions. 3. Refer to "Soil Classification System and Key' figure for an explanation of the graphics/symbols used. Test Pit TP-1 was terminated at 11 ft below site grades on 6/7/2022 Figure: Notes: Approximate Elevation Obtained from Jefferson County GIS Portal 5 ELEVATION/DEPTH SAMPLE & TEST DATA SOIL SAMPLE AND TEST DATA USCS SYMBOL SOIL PROFILE DESCRIPTION 0 1 2 3 4 5 6 7 8 9 10 7 8 9 10 11 12 d d d d d d W = 20.6GS OL CL-ML ML GP GP Medium stiff to stiff, black, moist, low plasticity ORGANIC SILTS(Topsoil) Stiff to very stiff, gray-brown (mottled), moist, sandy SILT with variable/elevated clay particles, trace gravel, occasional organics, rootlets (Outwash) Medium dense, gray-brown, moist, silty, very sandy, poorly graded GRAVEL, trace cobbles, occasional organics, roots (Outwash) Medium dense, brown, moist, sandy, poorly graded GRAVEL, trace silt, trace cobbles and boulders, occasional organics, roots (Outwash) Increased moisture GeoTest Services, Inc. TEST PIT LOG Test Pit No. TP-2 PROJECT: Southard - Proposed Shop and Residence LOCATION: 155 Night Owl Road, Port Townsend, WA EXPLORATION METHOD: Tracked Excavator CONTRACTOR/DRILLER: Moving Earth LLC PROJECT NO.: 22-0512 DATE: 6/7/2022 ELEVATION: Approx 142' LOGGED BY: CM/JR DEPTH TO WATER TABLE:MA PERCHED WATER:NA CAVING NA Reference Notes:1. Stratigraphic contacts are based on field interpretations and are approximate.2. Reference to the text of this report is necessary for a proper understanding of subsurface conditions.3. Refer to "Soil Classification System and Key' figure for an explanation of the graphics/symbols used. Test Pit TP-2 was terminated at 10.5 ft below site grades on 6/7/2022 Figure: Notes: Approximate Elevation Obtained from Jefferson County GIS Portal 6 ELEVATION/DEPTH SAMPLE & TEST DATA SOIL SAMPLE AND TEST DATA USCS SYMBOL SOIL PROFILE DESCRIPTION 0 1 2 3 4 5 6 7 8 9 10 13 14 15 16 17 18 d d d d d d GT W = 29.3GS OL ML ML GP Medium stiff, black, moist, low plasticity ORGANIC SILTS (Topsoil)Medium stiff to stiff, gray-brown (mottled), moist, sandy SILT, occasional organics, roots (Outwash) Very stiff, gray-brown, moist, sandy SILT, occasional organics, roots (Outwash) Medium dense, brown, moist, sandy, poorly graded GRAVEL, trace silt, trace cobbles, occasional organics, roots (Outwash) GeoTest Services, Inc. TEST PIT LOG Test Pit No. TP-3 PROJECT: Southard - Proposed Shop and Residence LOCATION: 155 Night Owl Road, Port Townsend, WA EXPLORATION METHOD: Tracked Excavator CONTRACTOR/DRILLER: Moving Earth LLC PROJECT NO.: 22-0512 DATE: 6/7/2022 ELEVATION: Approx 142' LOGGED BY: CM/JR DEPTH TO WATER TABLE:MA PERCHED WATER:NA CAVING NA Reference Notes:1. Stratigraphic contacts are based on field interpretations and are approximate.2. Reference to the text of this report is necessary for a proper understanding of subsurface conditions. 3. Refer to "Soil Classification System and Key' figure for an explanation of the graphics/symbols used. Test Pit TP-3 was terminated at 10.25 ft below site grades on 6/7/2022 Figure: Notes: Approximate Elevation Obtained from Jefferson County GIS Portal 7 ELEVATION/DEPTH SAMPLE & TEST DATA SOIL SAMPLE AND TEST DATA USCS SYMBOL SOIL PROFILE DESCRIPTION 0 1 2 3 4 5 6 7 8 9 10 19 20 21 22 23 24 d d d d d d GT W = 4.9GS ML ML GP GP Medium stiff, brown-gray (mottled), moist, sandy SILT, numerous organics, rootlets and woodStiff, gray-brown (mottled), moist, sandy SILT, trace gravel, occasional organics, roots and wood (Outwash) Medium dense, gray-brown, moist, very sandy, poorly graded GRAVEL, trace silt occasional organics, roots (Outwash) Medium dense, brown, moist, sandy, poorly graded GRAVEL, trace silt, trace cobbles, occasional organics, roots (Outwash) Trace boulders - coarsening gravel Increased cobbles and boulders - increased moisture GeoTest Services, Inc. TEST PIT LOG Test Pit No. TP-4 PROJECT: Southard - Proposed Shop and Residence LOCATION: 155 Night Owl Road, Port Townsend, WA EXPLORATION METHOD: Tracked Excavator CONTRACTOR/DRILLER: Moving Earth LLC PROJECT NO.: 22-0512 DATE: 6/7/2022 ELEVATION: Approx 142' LOGGED BY: CM/JR DEPTH TO WATER TABLE:MA PERCHED WATER:NA CAVING 5.5 Reference Notes:1. Stratigraphic contacts are based on field interpretations and are approximate.2. Reference to the text of this report is necessary for a proper understanding of subsurface conditions.3. Refer to "Soil Classification System and Key' figure for an explanation of the graphics/symbols used. Test Pit TP-4 was terminated at 10.25 ft below site grades on 6/7/2022 Figure: Notes: Approximate Elevation Obtained from Jefferson County GIS Portal 8 ELEVATION/DEPTH SAMPLE & TEST DATA SOIL SAMPLE AND TEST DATA USCS SYMBOL SOIL PROFILE DESCRIPTION This report may not be reproduced, except in full, without the prior written approval of GeoTest Services, Inc.Tested By: IZ Checked By: Client: Project: Project No.:Figure Charles Southard Southard - Proposed Shop and Residence 22-0512 9 SYMBOL SOURCE SAMPLE DEPTH Material Description USCSNO. (ft.) SOIL DATAPERCENT FINER0 10 20 30 40 50 60 70 80 90 100 GRAIN SIZE - mm. 0.1110 % +3"Coarse % Gravel Fine Coarse Medium % Sand Fine Silt % Fines 0 20 55 11 6 5 3 0 0 3 0 3 26 68 0 0 0 3 10 17 70 0 22 36 10 18 11 32 in.1½ in.1 in.¾ in.½ in.3/8 in.#4#10#20#30#40#60#100#140#200Sieve Analysis Test Report - ASTM C136/C117 TP-1 6 10.5 Sandy, poorly graded GRAVEL, trace silt GP TP-2 8 2.0 Sandy SILT, trace gravel ML TP-3 15 4.0 Sandy SILT ML TP-4 21 4.0 Very sandy, poorly graded GRAVEL, trace silt GP CM 2545 W Falls Avenue Kennewick, WA 99336 509.783.7450 www.nwag.com lab@nwag.com Sample ID pH Organic Matter Cation Exchange Capacity TP-1 @ 0.5’ 4.6 24.86% 31.2 meq/100g TP-3 @ 0.25’ 4.5 7.61% 17.3 meq/100g TP-4 @ 2.0’ 5.5 2.64% 20.5 meq/100g Method SM 4500-H+ B ASTM D2974 EPA 9081 GeoTest Services Inc. 741 Marine Drive Bellingham, WA 98225 Report: 59550-1-1 Date: June 14, 2022 Project No: 22-0512 Project Name: Proposed Shop and Residence WILDCAT DYNAMIC CONE LOG Page 1 of 1 GeoTest Services, Inc. 741 Marine Drive PROJECT NUMBER: 22-0512 Bellingham, WA 98225 DATE STARTED: 06-07-2022 DATE COMPLETED: 06-07-2022 HOLE #: DCP-1 CREW: CM/JR SURFACE ELEVATION: Approx. 142 feet PROJECT: Proposed Residence and Shop WATER ON COMPLETION:Not Determined ADDRESS: 155 Night Owl Road HAMMER WEIGHT: 35 lbs. LOCATION: Port Townsend, WA CONE AREA: 10 sq. cm BLOWS RESISTANCE GRAPH OF CONE RESISTANCE TESTED CONSISTENCY DEPTH PER 10 cm Kg/cm² 0 50 100 150 N' SAND & SILT CLAY -6 26.6 •••••••7 LOOSE MEDIUM STIFF -17 75.5 •••••••••••••••••••••21 MEDIUM DENSE VERY STIFF - 1 ft 16 71.0 ••••••••••••••••••••20 MEDIUM DENSE VERY STIFF -10 44.4 ••••••••••••12 MEDIUM DENSE STIFF -9 40.0 •••••••••••11 MEDIUM DENSE STIFF - 2 ft 10 44.4 ••••••••••••12 MEDIUM DENSE STIFF -16 71.0 ••••••••••••••••••••20 MEDIUM DENSE VERY STIFF -26 115.4 ••••••••••••••••••••••••••••••••• - DENSE HARD - 3 ft 32 142.1 ••••••••••••••••••••••••••••••••••••••••• - DENSE HARD - 1 m 43 190.9 •••••••••••••••••••••••••••••••••••••••••••••••••••••••- VERY DENSE HARD -32 123.5 ••••••••••••••••••••••••••••••••••• - DENSE HARD - 4 ft 31 119.7 •••••••••••••••••••••••••••••••••• - DENSE HARD -47 181.4 ••••••••••••••••••••••••••••••••••••••••••••••••••••- VERY DENSE HARD -50 193.0 •••••••••••••••••••••••••••••••••••••••••••••••••••••••- VERY DENSE HARD - 5 ft - - - 6 ft - - 2 m - 7 ft - - - 8 ft - - - 9 ft - - - 3 m 10 ft - - - - 11 ft - - - 12 ft - - - 4 m 13 ft WILDCAT.XLS WILDCAT DYNAMIC CONE LOG Page 1 of 1 GeoTest Services, Inc. 741 Marine Drive PROJECT NUMBER: 22-0512 Bellingham, WA 98225 DATE STARTED: 06-07-2022 DATE COMPLETED: 06-07-2022 HOLE #: DCP-2 CREW: CM/JR SURFACE ELEVATION: Approx. 142 feet PROJECT: Proposed Residence and Shop WATER ON COMPLETION:Not Determined ADDRESS: 155 Night Owl Road HAMMER WEIGHT: 35 lbs. LOCATION: Port Townsend, WA CONE AREA: 10 sq. cm BLOWS RESISTANCE GRAPH OF CONE RESISTANCE TESTED CONSISTENCY DEPTH PER 10 cm Kg/cm² 0 50 100 150 N' SAND & SILT CLAY -8 35.5 ••••••••••10 LOOSE STIFF -15 66.6 •••••••••••••••••••19 MEDIUM DENSE VERY STIFF - 1 ft 16 71.0 ••••••••••••••••••••20 MEDIUM DENSE VERY STIFF -3 13.3 •••3 VERY LOOSE SOFT -3 13.3 •••3 VERY LOOSE SOFT - 2 ft 6 26.6 •••••••7 LOOSE MEDIUM STIFF -12 53.3 •••••••••••••••15 MEDIUM DENSE STIFF -14 62.2 ••••••••••••••••••17 MEDIUM DENSE VERY STIFF - 3 ft 10 44.4 ••••••••••••12 MEDIUM DENSE STIFF - 1 m 11 48.8 ••••••••••••••13 MEDIUM DENSE STIFF -18 69.5 ••••••••••••••••••••19 MEDIUM DENSE VERY STIFF - 4 ft 21 81.1 •••••••••••••••••••••••23 MEDIUM DENSE VERY STIFF -25 96.5 •••••••••••••••••••••••••••- MEDIUM DENSE VERY STIFF -50 193.0 •••••••••••••••••••••••••••••••••••••••••••••••••••••••- VERY DENSE HARD - 5 ft - - - 6 ft - - 2 m - 7 ft - - - 8 ft - - - 9 ft - - - 3 m 10 ft - - - - 11 ft - - - 12 ft - - - 4 m 13 ft WILDCAT.XLS WILDCAT DYNAMIC CONE LOG Page 1 of 1 GeoTest Services, Inc. 741 Marine Drive PROJECT NUMBER: 22-0512 Bellingham, WA 98225 DATE STARTED: 06-07-2022 DATE COMPLETED: 06-07-2022 HOLE #: DCP-3 CREW: CM/JR SURFACE ELEVATION: Approx. 142 feet PROJECT: Proposed Residence and Shop WATER ON COMPLETION:Not Determined ADDRESS: 155 Night Owl Road HAMMER WEIGHT: 35 lbs. LOCATION: Port Townsend, WA CONE AREA: 10 sq. cm BLOWS RESISTANCE GRAPH OF CONE RESISTANCE TESTED CONSISTENCY DEPTH PER 10 cm Kg/cm² 0 50 100 150 N' SAND & SILT CLAY -15 66.6 •••••••••••••••••••19 MEDIUM DENSE VERY STIFF -14 62.2 ••••••••••••••••••17 MEDIUM DENSE VERY STIFF - 1 ft 9 40.0 •••••••••••11 MEDIUM DENSE STIFF -7 31.1 •••••••••8 LOOSE MEDIUM STIFF -7 31.1 •••••••••8 LOOSE MEDIUM STIFF - 2 ft 11 48.8 ••••••••••••••13 MEDIUM DENSE STIFF -11 48.8 ••••••••••••••13 MEDIUM DENSE STIFF -12 53.3 •••••••••••••••15 MEDIUM DENSE STIFF - 3 ft 14 62.2 ••••••••••••••••••17 MEDIUM DENSE VERY STIFF - 1 m 17 75.5 •••••••••••••••••••••21 MEDIUM DENSE VERY STIFF -18 69.5 ••••••••••••••••••••19 MEDIUM DENSE VERY STIFF - 4 ft 28 108.1 •••••••••••••••••••••••••••••••- MEDIUM DENSE VERY STIFF -50 193.0 •••••••••••••••••••••••••••••••••••••••••••••••••••••••- VERY DENSE HARD - - 5 ft - - - 6 ft - - 2 m - 7 ft - - - 8 ft - - - 9 ft - - - 3 m 10 ft - - - - 11 ft - - - 12 ft - - - 4 m 13 ft WILDCAT.XLS WILDCAT DYNAMIC CONE LOG Page 1 of 1 GeoTest Services, Inc. 741 Marine Drive PROJECT NUMBER: 22-0512 Bellingham, WA 98225 DATE STARTED: 06-07-2022 DATE COMPLETED: 06-07-2022 HOLE #: DCP-4 CREW: CM/JR SURFACE ELEVATION: Approx. 142 feet PROJECT: Proposed Residence and Shop WATER ON COMPLETION:Not Determined ADDRESS: 155 Night Owl Road HAMMER WEIGHT: 35 lbs. LOCATION: Port Townsend, WA CONE AREA: 10 sq. cm BLOWS RESISTANCE GRAPH OF CONE RESISTANCE TESTED CONSISTENCY DEPTH PER 10 cm Kg/cm² 0 50 100 150 N' SAND & SILT CLAY -4 17.8 •••••5 LOOSE MEDIUM STIFF -12 53.3 •••••••••••••••15 MEDIUM DENSE STIFF - 1 ft 21 93.2 •••••••••••••••••••••••••••- MEDIUM DENSE VERY STIFF -16 71.0 ••••••••••••••••••••20 MEDIUM DENSE VERY STIFF -9 40.0 •••••••••••11 MEDIUM DENSE STIFF - 2 ft 8 35.5 ••••••••••10 LOOSE STIFF -11 48.8 ••••••••••••••13 MEDIUM DENSE STIFF -13 57.7 ••••••••••••••••16 MEDIUM DENSE VERY STIFF - 3 ft 12 53.3 •••••••••••••••15 MEDIUM DENSE STIFF - 1 m 38 168.7 ••••••••••••••••••••••••••••••••••••••••••••••••- DENSE HARD -50 193.0 •••••••••••••••••••••••••••••••••••••••••••••••••••••••- VERY DENSE HARD - 4 ft - - - 5 ft - - - 6 ft - - 2 m - 7 ft - - - 8 ft - - - 9 ft - - - 3 m 10 ft - - - - 11 ft - - - 12 ft - - - 4 m 13 ft WILDCAT.XLS 1 1Information in this document is based upon material developed by ASFE, Professional Firms Practicing in the Geosciences(asfe.org) REPORT LIMITATIONS AND GUIDELINES FOR ITS USE1 Subsurface issues may cause construction delays, cost overruns, claims, and disputes. While you cannot eliminate all such risks, you can manage them. The following information is provided to help: Geotechnical Services are Performed for Specific Purposes, Persons, and Projects At GeoTest our geotechnical engineers and geologists structure their services to meet specific needs of our clients. A geotechnical engineering study conducted for a civil engineer may not fulfill the needs of an owner, a construction contractor or even another civil engineer. Because each geotechnical engineering study is unique, each geotechnical engineering report is unique, prepared solely for the client. No one except you should rely on your geotechnical engineer who prepared it. And no one – not even you – should apply the report for any purpose or project except the one originally contemplated. Read the Full Report Serious problems have occurred because those relying on a geotechnical engineering report did not read it all. Do not rely on an executive summary. Do not read selected elements only. A Geotechnical Engineering Report is Based on a Unique Set of Project-Specific Factors GeoTest’s geotechnical engineers consider a number of unique, project-specific factors when establishing the scope of a study. Typical factors include: the clients goals, objectives, and risk management preferences; the general nature of the structure involved its size, and configuration; the location of the structure on the site; and other planned or existing site improvements, such as access roads, parking lots, and underground utilities. Unless GeoTest, who conducted the study specifically states otherwise, do not rely on a geotechnical engineering report that was: • not prepared for you, • not prepared for your project, • not prepared for the specific site explored, or • completed before important project changes were made. 2 1Information in this document is based upon material developed by ASFE, Professional Firms Practicing in the Geosciences(asfe.org) Typical changes that can erode the reliability of an existing geotechnical engineering report include those that affect: • the function of the proposed structure, as when it’s changed, for example, from a parking garage to an office building, or from a light industrial plant to a refrigerated warehouse, • elevation, configuration, location, orientation, or weight of the proposed construction, • alterations in drainage designs; or • composition of the design team; the passage of time; man-made alterations and construction whether on or adjacent to the site; or by natural alterations and events, such as floods, earthquakes or groundwater fluctuations; or project ownership. Always inform GeoTest’s geotechnical engineer of project changes – even minor ones – and request an assessment of their impact. Geotechnical engineers cannot accept responsibility or liability for problems that occur because their reports do not consider developments of which they were not informed. Subsurface Conditions Can Change This geotechnical or geologic report is based on conditions that existed at the time the study was performed. Do not rely on the findings and conclusions of this report, whose adequacy may have been affected by: the passage of time; by man-made events, such as construction on or adjacent to the site; or by natural events, such as floods, earthquakes, or groundwater fluctuations. Always contact GeoTest before applying the report to determine if it is still relevant. A minor amount of additional testing or analysis will help determine if the report remains applicable. Most Geotechnical and Geologic Findings are Professional Opinions Our site exploration identifies subsurface conditions only at those points where subsurface tests are conducted or samples are taken. GeoTest’s engineers and geologists review field and laboratory data and then apply their professional judgment to render an opinion about subsurface conditions throughout the site. Actual subsurface conditions may differ – sometimes significantly – from those indicated in your report. Retaining GeoTest who developed this report to provide construction observation is the most effective method of managing the risks associated with anticipated or unanticipated conditions. 3 1Information in this document is based upon material developed by ASFE, Professional Firms Practicing in the Geosciences(asfe.org) A Report’s Recommendations are Not Final Do not over-rely on the construction recommendations included in this report. Those recommendations are not final, because geotechnical engineers or geologists develop them principally from judgment and opinion. GeoTest’s geotechnical engineers or geologists can finalize their recommendations only by observing actual subsurface conditions revealed during construction. GeoTest cannot assume responsibility or liability for the report’s recommendations if our firm does not perform the construction observation. A Geotechnical Engineering or Geologic Report may be Subject to Misinterpretation Misinterpretation of this report by other design team members can result in costly problems. Lower that risk by having GeoTest confer with appropriate members of the design team after submitting the report. Also, we suggest retaining GeoTest to review pertinent elements of the design teams plans and specifications. Contractors can also misinterpret a geotechnical engineering report. Reduce that risk by having GeoTest participate in pre-bid and preconstruction conferences, and by providing construction observation. Do not Redraw the Exploration Logs Our geotechnical engineers and geologists prepare final boring and testing logs based upon their interpretation of field logs and laboratory data. To prevent errors of omissions, the logs included in this report should never be redrawn for inclusion in architectural or other design drawings. Only photographic or electronic reproduction is acceptable; but recognizes that separating logs from the report can elevate risk. Give Contractors a Complete Report and Guidance Some owners and design professionals mistakenly believe they can make contractors liable for unanticipated subsurface conditions by limiting what they provide for bid preparation. To help prevent costly problems, give contractors the complete geotechnical engineering report, but preface it with a clearly written letter of transmittal. In that letter, consider advising the contractors that the report was not prepared for purposes of bid development and that the report’s accuracy is limited; encourage them to confer with GeoTest and/or to conduct additional study to obtain the specific types of information they need or prefer. A pre-bid conference can also be valuable. Be sure contractors have sufficient time to perform additional study. Only then might you be in a position to give contractors the best information available, while requiring them to at least share some of the financial responsibilities stemming from unanticipated conditions. 4 1Information in this document is based upon material developed by ASFE, Professional Firms Practicing in the Geosciences(asfe.org) In addition, it is recommended that a contingency for unanticipated conditions be included in your project budget and schedule. Read Responsibility Provisions Closely Some clients, design professionals, and contractors do not recognize that geotechnical engineering or geology is far less exact than other engineering disciplines. This lack of understanding can create unrealistic expectations that can lead to disappointments, claims, and disputes. To help reduce risk, GeoTest includes an explanatory limitations section in our reports. Read these provisions closely. Ask questions and we encourage our clients or their representative to contact our office if you are unclear as to how these provisions apply to your project. Environmental Concerns Are Not Covered in this Geotechnical or Geologic Report The equipment, techniques, and personnel used to perform an environmental study differ significantly from those used to perform a geotechnical or geologic study. For that reason, a geotechnical engineering or geologic report does not usually relate any environmental findings, conclusions, or recommendations; e.g., about the likelihood of encountering underground storage tanks or regulated containments, etc. If you have not yet obtained your own environmental information, ask your geotechnical consultant for risk management guidance. Do not rely on environmental report prepared for some one else. Obtain Professional Assistance to Deal with Biological Pollutants Diverse strategies can be applied during building design, construction, operation, and maintenance to prevent significant amounts biological pollutants from growing on indoor surfaces. Biological pollutants includes but is not limited to molds, fungi, spores, bacteria and viruses. To be effective, all such strategies should be devised for the express purpose of prevention, integrated into a comprehensive plan, and executed with diligent oversight by a professional biological pollutant prevention consultant. Because just a small amount of water or moisture can lead to the development of severe biological infestations, a number of prevention strategies focus on keeping building surfaces dry. While groundwater, water infiltration, and similar issues may have been addressed as part of this study, the geotechnical engineer or geologist in charge of this project is not a biological pollutant prevention consultant; none of the services preformed in connection with this geotechnical engineering or geological study were designed or conducted for the purpose of preventing biological infestations.