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-aovoS /,' 7e7sw r-2 JO,4 GEODESIGN= RECEIVED ,J U N 2 2 2020 ` CITY OF TIGARD BUILDING DIVISION • REPORT OF GEOTECHNICAL ENGINEERING SERVICES 72"d and Dartmouth Development Northeast Corner of SW Dartmouth Street and SW 72nd Avenue Tigard, Oregon For ScanlanKemperBard February 18, 2019 GeoDesign Project: SKB-1 5-01 REDESIGN' February 18, 2019 \'‘-'..."----'s\--..._ Scanlan KernperBard 222 SW Columbia Street, Suite 700 Portland, OR 97201 Attention: Will Short Report of Geotechnical Engineering Services 72"d and Dartmouth Development Northeast Corner of SW Dartmouth Street and SW 72"d Avenue Tigard, Oregon GeoDesign Project: SKB-1 5-01 GeoDesign, Inc. is pleased to submit this report of geotechnical engineering services for the proposed development located at SW 72'Avenue and SW Dartmouth Street in Tigard, Oregon. Our services for this project were conducted in accordance with our proposal dated January 2, 2019. We appreciate the opportunity to be of continued service to you. Please contact us if you have questions regarding this report. Sincerely, GeoDesign, Inc. 11J/ l Nick Paveglio, P.E. Brett A. Shipton, P.E., G.E. Senior Associate Engineer Principal Engineer NNP:BAS:kt Attachments One copy submitted(via email only) Document ID:SKB-1 5-01-021 81 9-geor.docx ©2019 GeoDesign, Inc. All rights reserved. 9450 SW Commerce Circle,Suite 300 I Wilsonville,OR 97070 I 503 968.8787 www.geodesigninc.com • EXECUTIVE SUMMARY Based on our understanding of the project and the results of explorations, laboratory testing, and analyses, it is our opinion that the proposed development is feasible from a geotechnical standpoint. The primary geotechnical considerations for the project are summarized as follows: • Column loads under 400 kips can be supported by conventional spread footings on 2-foot- thick granular pads that bear on native soil. Column loads greater than 400 kips should be supported on conventional spread footings bearing on rammed aggregate piers. • Groundwater was measured at approximately 8 feet BGS in piezometers installed at the site. Dewatering will be required to construct the basement structure and utilities. • Permanent basement structures that extend below the water table must be waterproofed and designed for full hydrostatic pressures. Alternatively, a permanent subsurface drainage system can be installed behind the basement walls and below the slab. • Liquefaction and lateral spreading are not design considerations at the site. • Based on the soil and groundwater conditions at the site, on-site infiltration systems are not feasible. • The site soil is sensitive to moisture and is easily disturbed when at a moisture content that is above optimum. The subgrade should be protected from construction traffic. G EODESIGN= SKB-1 s-01:021819 TABLE OF CONTENTS PAGE NO. ACRONYMS AND ABBREVIATIONS 1.0 INTRODUCTION 1 2.0 PROJECT UNDERSTANDING 1 3.0 PURPOSE AND SCOPE 1 4.0 SITE CONDITIONS 2 4.1 Surface Conditions 2 4.2 Subsurface Conditions 2 4.3 Infiltration Testing 3 5.0 SEISMIC HAZARDS 3 5.1 Liquefaction and Lateral Spread 3 6.0 SITE DEVELOPMENT RECOMMENDATIONS 4 6.1 Site Preparation 4 6.2 Construction Considerations 4 6.3 Excavation 5 6.4 Dewatering 5 6.5 Temporary Slopes 6 6.6 Erosion Control 6 6.7 Shoring 6 6.8 Materials 8 6.9 Permanent Cut and Fill Slopes 12 6.10 Pavements 12 7.0 FOUNDATION SUPPORT RECOMMENDATIONS 14 7.1 Conventional Spread Footings 14 7.2 Spread Footings Supported on Rammed Aggregate Piers 15 7.3 Slabs on Grade 15 8.0 PERMANENT RETAINING STRUCTURES 16 9.0 DRAINAGE CONSIDERATIONS 16 9.1 General 16 9.2 Infiltration Systems 16 10.0 GROUNDWATER 16 11.0 SEISMIC DESIGN CRITERIA 17 12.0 OBSERVATION OF CONSTRUCTION 17 13.0 LIMITATIONS 17 FIGURES Vicinity Map Figure 1 Site Plan Figure 2 Cantilevered and Braced Walls Design Criteria Figure 3 Surcharge-Induced Lateral Earth Pressures Figure 4 G EO DESIGN? SKB-15-01:021819 TABLE OF CONTENTS PAGE NO. APPENDICES Appendix A Field Explorations A-1 Laboratory Testing A-1 Exploration Key Table A-1 Soil Classification System Table A-2 Boring Logs Figures A-1 -A-4 Atterberg Limits Test Results Figure A-5 Consolidation Test Results Figure A-6 Summary of Laboratory Data Figure A-7 SPT Hammer Calibration Appendix B Previous Explorations B-1 Exploration Logs and Laboratory Testing Results GEODESIGN= SKB-1 5-01:021819 ACRONYMS AND ABBREVIATIONS AASHTO American Association of State Highway and Transportation Officials ACP asphalt concrete pavement ASTM American Society for Testing and Materials BGS below ground surface g gravitational acceleration (32.2 feet/second') H:V horizontal to vertical IBC International Building Code ksf kips per square foot MCE maximum considered earthquake NGVD National Geodetic Vertical Datum OSSC Oregon Standard Specifications for Construction (2018) PCC portland cement concrete pcf pounds per cubic foot pci pounds per cubic inch PG performance grade psf pounds per square foot psi pounds per square inch PVC polyvinyl chloride SPT standard penetration test GEODESIC-'N= SKB-15-01:021819 1.0 INTRODUCTION This report presents the results of GeoDesign's geotechnical engineering evaluation for the proposed development to be located northeast of the intersection of SW 72"'Avenue and SW Dartmouth Street in Tigard, Oregon. The site location is shown relative to surrounding features on Figure 1. Acronyms and abbreviations used herein are defined at the end of this document. All elevations referred to in this report are relative to the NGVD 29 datum. 2.0 PROJECT UNDERSTANDING The 1.72-acre site includes Tax Lots 4000, 4100, 4200, 4300, and 4402. The property is generally a grass-covered field, except for Tax Lot 4000 where a single-family residential structure is present. Single-family residences formerly occupied Tax Lots 4100, 4300, and 4402, but these were demolished between 201 5 and 2016. The site slopes down from northeast to southwest, with elevations generally between 21 3 and 242 feet. Development plans consist of a five-story building with a single basement level. Foundation loads were not available at the time of this report. We have assumed maximum column and wall loads of 600 kips and 6 kips per foot, respectively. Because the site slopes, cuts could be up to 20 feet deep. 3.0 PURPOSE AND SCOPE The purpose of our services was to provide geotechnical engineering recommendations for use in design and construction of the proposed development. The specific scope of our services completed is summarized as follows: • Reviewed readily available, published geologic data and our in-house files for existing information on subsurface conditions in the site vicinity. • Conducted a subsurface exploration program that consisted of drilling four borings to depths between 31.5 and 61.5 feet BGS. • Installed a vibrating wire piezometer in one of the borings to measure groundwater levels. • Conducted infiltration testing in the borings between depths of 10.0 and 20.0 feet BGS. • Maintained continuous logs of the explorations and collected soil samples at representative intervals. • Conducted a laboratory testing program that consisted of the following tests: • Twelve moisture content determinations in general accordance with ASTM D2216 • Three Atterberg Limits test in accordance with ASTM D4318 • Four particle-size analyses in general accordance with ASTM D1 140 • One consolidation test in general accordance with ASTM D2435 • Prepared this geotechnical engineering report that presents our findings, conclusions, and recommendations, including the following: • Soil and groundwater conditions • Recommendations for site preparation and grading, including temporary and permanent slopes, fill placement criteria, suitability of on-site soil for fill, and subgrade preparation • Recommendations for wet weather construction GEODESIGN_ 1 SKB-15-01:021 81 9 • Discussion of seismic hazards at the site • Recommendations for temporary shoring • Recommendations for foundation support and recommendations for design capacity for the proposed building • Recommendations for use in design of conventional retaining walls, including backfill and drainage requirements and lateral earth pressures • General recommendations for dewatering during construction and subsurface drainage 4.0 SITE CONDITIONS 4.1 SURFACE CONDITIONS The 1.72-acre site includes Tax Lots 4000, 4100, 4200, 4300, and 4402. The site is bound by SW Clinton Street to the north, a single-family residence and office building to the east, SW Dartmouth Street to the south, and SW 72'Avenue to the west. The property is generally a grass-covered field, except for Tax Lot 4000 where a single-family residential structure is present. Single-family residences formerly occupied Tax Lots 4100, 4300, and 4402, but were demolished between 201 5 and 2016. The site slopes down from the northeast to southwest, with elevations generally between 213 and 242 feet. 4.2 SUBSURFACE CONDITIONS Four borings and five test pits were previously completed at the site by Geotech Solutions in 2008. The borings were drilled to the depths between 31 .5 and 51.5 feet BGS and the test pits were excavated to a depth of 12.0 feet BGS. The previous work was supplemented by drilling four borings (B-1 through B-4) to depths between 31.5 and 61 .5 feet BGS. Figure 2 shows the approximate exploration locations. The exploration logs and results of our laboratory testing program are presented in Appendix A. The exploration logs and laboratory results from the Geotech Solutions work are presented in Appendix B. Subsurface conditions encountered in the explorations consist of 15 to 30 feet of very soft to medium stiff silt underlain by generally stiff to very stiff silt to the maximum depth explored of 61.5 feet BGS. The following sections provide a more detailed description of the geologic units encountered. 4.2.1 Soil Conditions 4.2.1.1 Topsoil A topsoil zone up to 1 .5 feet BGS with a 2- to- 8-inch-thick root zone was observed in the explorations at the site. 4.2.1.2 Fill Below the topsoil we expect areas of silt fill with construction debris from previous site development. The fill will likely be concentrated near former structures and generally extend to depths between 2.0 and 5.0 feet BGS. Areas of deeper fill could also be present where basements were present. G FODESIGN= 2 SKB-1 5-01:021819 4.2.1.3 Alluvial Silt Silt underlies the silt fill to depths of 15.0 to 30.0 feet BGS. SPTs indicate the silt is medium stiff with an approximately 10-foot-thick, very soft to soft zone occurring between depths of 10.0 and 25.0 feet BGS. The silt is brown to depths of 15 to 20 feet and gray below. The silt has trace to minor sand and is moist above 10.0 to 1 5.0 feet BGS and moist to wet below. Laboratory testing indicates the silt has low plasticity with moisture contents between 30 and 36 percent at the time of our explorations. 4.2. 1.4 Weathered Basalt Severely weathered basalt typically classified as stiff to hard silt is present below depths of 15.0 to 30.0 feet BGS. The silt is brown-orange with weathered basalt nodules. It is moist and extends to maximum depth explored of 61.5 feet BGS. Laboratory testing indicates the silt has low plasticity and moisture contents between 26 and 35 percent at the time of explorations. 4.2.2 Groundwater A vibrating wire piezometer was installed in boring B-4 to measure groundwater levels. Multiple readings taken on January 31 , 2019 and February 7, 2019 indicate groundwater at a depth of approximately 9 feet BGS. This is consistent with the monitoring well installed in boring B-2 by Geotech Solutions in 2008 (groundwater at 8.3 feet BGS). Perched water could be present above the measured depths, particularly in the wet season. 4.3 INFILTRATION TESTING Infiltration testing was conducted in borings B-1 through B-4 at depths between 10.0 of 20.0 and 1 5.0 feet BGS using the single-ring infiltration method. Table 1 summarizes the infiltration testing results. Table 1. Infiltration Testing Results Depth Observed Fine Content Exploration Soil Description Infiltration Rate (feet BGS) (percent) (inches/hour) B-1 10.0 Silt —0.0 89 B-2 15.0 Silt —0.0 95 B-3 20.0 Silt —0.0 86 B-4 15.0 Silt —0.0 97 5.0 SEISMIC HAZARDS 5. 1 LIQUEFACTION AND LATERAL SPREADING Liquefaction is caused by a rapid increase in pore water pressure that reduces the effective stress between soil particles to near zero. Granular soil, which relies on interparticle friction for strength, is susceptible to liquefaction until the excess pore pressures can dissipate. In general, loose, saturated sand soil with low silt and clay content is the most susceptible to liquefaction. Silty soil with low plasticity is moderately susceptible to liquefaction under relatively higher levels of ground shaking. G EO DESIGN= 3 SKB-15-01:021819 Lateral spreading is a liquefaction-related seismic hazard and occurs on gently sloping or flat sites underlain by liquefiable sediment adjacent to an open face, such as a riverbank. Liquefied soil adjacent to an open face can flow toward the open face, resulting in lateral ground displacement. The primary difference between a conventional slope stability failure and lateral spreading is that no distinct failure plane is formed during a lateral spreading event. Liquefied soil flows downslope or to an exposed bank like the behavior of a viscous fluid. Based on subsurface conditions, negligible levels of liquefaction are expected under design levels of ground shaking. Consequently, lateral spreading is not a design considerations for the project. 6.0 SITE DEVELOPMENT RECOMMENDATIONS 6.1 SITE PREPARATION Demolition includes removal of the existing structures, concrete curbs, and abandoned utilities. Demolished material should be transported off site for disposal. Excavations remaining from removing the floor slab, foundations, utilities, and other subsurface elements should be backfilled with structural fill where below planned site grades. Excavation bases should expose firm subgrade before backfilling. The sides of the excavations should be cut into firm material and sloped a minimum of 1.5H:1V. Utility lines abandoned under new structural components should be completely removed and backfilled with structural fill. Soft or loose soil encountered during site preparation should be replaced with structural fill. 6.2 CONSTRUCTION CONSIDERATIONS The fine-grained soil present on this site is easily disturbed. Site preparation, utility trench work, and roadway excavation can create extensive soft areas and significant repair costs. Earthwork planning, regardless of the time of year, should include considerations for minimizing subgrade disturbance. Granular haul roads, staging areas, and a working blanket at the bottom of the basement will be necessary for support of construction traffic during the rainy season or when the moisture content of the surficial soil is more than a few percentage points above optimum. The thickness will depend on the contractor's means and methods and, accordingly, should be the contractor's responsibility. Based on our experience, between 12 and 18 inches of imported granular material is generally required in staging areas and between 18 and 24 inches in haul roads areas. Typical working blankets are 12 to 18 inches in thickness. In addition, a geotextile fabric can be placed as a barrier between the subgrade and imported granular material in areas of repeated construction traffic in haul roads and staging areas. The imported granular material, stabilization material, and geotextile fabric should meet the specifications in the "Materials" section. As an alternative to thickened crushed rock sections, haul roads and utility work zones may be constructed using cement-amended subgrades overlain by a crushed rock wearing surface. If this approach is used, the thickness of granular material in staging areas and along haul roads can typically be reduced to between 6 and 9 inches. This recommendation is based on an assumed minimum unconfined compressive strength of 100 psi for subgrade amended to a G EO DESI G Nz 4 SKB-15-01:021819 depth of 12 to 16 inches. The actual thickness of the amended material and imported granular material will depend on the contractor's means and methods and, accordingly, should be the contractor's responsibility. Cement amendment is discussed in the "Materials" section. 6.3 EXCAVATION 6.3.1 General Groundwater was generally observed between depths of 8 and 20 feet BGS with zones of additional seepage within 2 to 3 feet of the ground surface. Accordingly, the contractor should expect to install external dewatering wells and shore excavations where excavation occurs below groundwater. 6.3.2 Excavation Excavations shallower than 4 feet will not require shoring, provided groundwater seepage does not occur. Open excavation techniques may be used between 4 and 10 feet, provided the walls of the excavation are cut at a slope of 1.5H:1 V and groundwater seepage is not present. Sloughing and/or caving could occur if the excavation extends below groundwater. The walls of the trench should be shored and the area dewatered if seepage is encountered. It may be necessary to use tight joint, driven sheet piling to control groundwater seepage and loss of ground in trench areas adjacent to existing improvements. If shoring is used, we recommend that the type and design of the shoring system be the responsibility of the contractor, who is in the best position to choose a system that fits the overall plan of operation. 6.4 DEWATERING The contractor should be made responsible for temporary drainage of surface water, perched water, and groundwater as necessary to prevent standing water and/or erosion at the working surface. Groundwater was measured at a depth of 8 feet BGS in vibrating wire piezometers installed at the site. Zones of perched water were also observed within 5 feet of ground surface. The contractor should dewater excavations below the groundwater. The proposed dewatering plan should be capable of maintaining groundwater levels at least 2 feet below the base of excavations (including the depth required for stabilization material and foundations). In addition to safety considerations, running soil, caving, or other loss of ground will increase backfill volumes and can result in damage to adjacent structures or utilities. Flow rates for dewatering are likely to vary from slow to moderate depending on location, depth, soil type, and the season in which the excavation occurs. The dewatering systems should be capable of adapting to variable flows. Because of the tendency of saturated, low plasticity silt and sand to "run,"we recommend that dewatering wells or well points be considered if excavations extend below groundwater. It may be possible to control groundwater levels using a sump pump over short distances; well points or other more extensive dewatering systems may be required over long trench distances or large areal excavations for the basement. If groundwater is present at the base of utility excavations, we recommend placing 2 to 3 feet of stabilization material at the base of the excavation. The use of a subgrade geotextile fabric may reduce the amount of stabilization material required. The actual thickness should be based on field observations during construction. GEODESIGNV 5 SKR-15-01:021819 Trench stabilization material and the subgrade geotextile fabric should meet the requirements described in the "Materials" section. Trench stabilization material should be placed in one lift and compacted until well keyed. While we have described certain approaches to excavation dewatering, it is the contractor's responsibility to select the dewatering methods. 6.5 TEMPORARY SLOPES Excavation side slopes less than 10 feet high should be no steeper than 1 .5H:1 V, provided groundwater seepage does not occur. If slopes greater than 10 feet high are required, GeoDesign should be contacted to make additional recommendations. We recommend a minimum horizontal distance of 5 feet from the edge of the existing improvements to the top of the temporary slope. All cut slopes should be protected from erosion by covering them during wet weather. If sloughing or instability is observed, the slope should be flattened or supported by shoring. Excavations should not undermine adjacent utilities, foundations, walkways, streets, or other hardscapes unless special shoring or underpinned support is provided. 6.6 EROSION CONTROL The on-site soil is moderately susceptible to erosion. Slopes should be covered with an appropriate erosion control product. We recommend all slope surfaces be planted as soon as practical to minimize erosion. Surface water runoff should be collected and directed away from slopes to prevent water from running down the slope face. Erosion control measures such truck tire washers and temporary detention and settling basins should be used in accordance with local and state ordinances. 6.7 SHORING 6.7.1 General Shoring will be required where excavations are adjacent to existing improvements where sloping is not possible. Anchors will be necessary where excavations are adjacent to settlement-sensitive structures. Cantilevered shoring may be possible to support the one-level, below-grade excavations adjacent to rights-of-way if some settlement can be tolerated. Settlement of cantilevered shoring at the ground surface of approximately 0.5 to 1 inch at the shoring face is typical and becomes negligible a horizontal distance of 10 feet from the shoring. We recommend adjacent facilities be surveyed and existing cracks measured prior to, during, and after construction of the shoring and completion of the basement level excavation. We also recommend the condition of adjacent structures be photographed prior to excavation. If settlement or damage is observed in adjacent structures, GeoDesign should be contacted to provide additional recommendations. 6.7.2 Cantilever Shoring Cantilever soldier pile shoring can be designed using the values presented on Figure 3. Figure 3 assumes that walls can rotate slightly around their base and groundwater will be below the base of the walls. GEODESIGN= 6 SKB-1 s-01:021819 Figure 3 does not include surcharge loads such as crane pads and traffic loading. The values on Figure 4 should be used to compute surcharge-induced lateral earth pressures. A surcharge load of 250 psf should be applied at the surface of the retained soil where the wall shoring retains roadways. The design equivalent fluid pressure should also be increased for walls that retain sloping soil. We recommend the following lateral earth pressures be increased using the following factors (Table 2) when designing walls that retain sloping soil. Table 2. Lateral Earth Pressure Increase Factors for Sloping Soil Backfill Slope of Retained Soil Lateral Earth Pressure (degrees) Increase Factor 0 1.00 5 1.06 10 1.12 20 1.33 25 1 ,52 30 2.27 6.7.3 Anchored Shoring Anchored soldier pile shoring can be designed using the values presented on Figure 3. These values do not include surcharged-induced lateral earth pressures. Figure 4 should be used to compute surcharge-induced lateral earth pressures. We recommend a vertical live load of 250 psf be applied at the surface of the retained soil where the wall shoring retains roadways. If slopes are present behind walls, the equivalent fluid pressures on Figure 3 should be increased per Table 2. Structural design of the soldier piles should consider the lateral earth pressures discussed above. In addition to lateral earth pressures, the soldier piles will be subject to compressive forces as a result of the downward component of the tieback anchor loads. We recommend the tips of soldier piles be embedded at least 10 feet below the base of the excavation. A bearing capacity of 2,500 psf can be assumed in the silt at the tip of the soldier piles. The bonded zone for the tieback anchors should be maintained outside of the "unbonded zone" show on Figure 3. We anticipate that the tieback anchors can achieve allowable bond strength of between 0.25 and 1 .0 ksf in the silty soil depending on the method of construction. A variety of methods are available for construction of tieback anchors. Therefore, we recommend the contractor be responsible for selecting the appropriate bonded length and installation methods to achieve the required anchor capacity. Tieback anchors should be locked off at 100 percent of the design load. Prior to installing production anchors, we recommend performance testing be conducted on a minimum of two anchors. The purpose of the testing is to verify the installation procedure GEODESIGNO. 7 SKB-1 S-01:021819 • selected by the contractor before a large number of anchors are installed. We recommend proof testing be conducted on all production anchors. Performance and proof testing should be performed in accordance with the guidelines provided in Recommendations for Prestressed Rock and Soil Anchors(Post Tensioning Institute, 2014). We anticipate lagging will consist of pressure-treated lumber. To maintain the integrity of the excavation, prompt and careful installation of lagging, particularly in areas of seepage and loose soil, is recommended. All voids behind the lagging should be completely backfilled with grout slurry. Anchors may need to extend into the City of Tigard rights-of-way and adjacent buildings, which will require temporary easements. Anchors may need to be de-tensioned but can likely remain in place once the structural walls are in place. Prior to the start of construction, tieback locations and inclinations should be checked to verify that they do not interfere with existing foundations or buried utilities. 6.8 MATERIALS Structural fill should be free of organic matter and other deleterious materials and, in general, should consist of particles no larger than 3 inches in diameter. Existing concrete debris or remnant concrete structural elements, asphalt pavement, and aggregate base can be used as structural fill, provided it is adequately processed as described below for recycled concrete or broken into particles no greater than 6 inches in greatest dimension and can be incorporated into well-graded structural fill and adequately compacted. 6.8.1 On-Site Soil The on-site silt is suitable for use as structural fill, provided it meets the specifications provided in OSSC 00330.12 (Borrow Material). Based on laboratory test results, the moisture content of the on-site silt was greater than the anticipated optimum moisture content required for satisfactory compaction. Moisture conditioning (drying) will be required to use on-site silty soil for structural fill. Accordingly, extended dry weather and sufficient area to dry the soil will be required to adequately condition the soil for use as structural fill. When used as structural fill, the on-site silty soil should be placed in lifts with a maximum uncompacted thickness of 8 inches and compacted to not less than 92 percent of the maximum dry density, as determined by ASTM D1 557. 6.8.2 Imported Granular Material Imported granular material should be pit- or quarry-run rock, crushed rock, or crushed gravel and sand that is fairly well graded between coarse and fine and has less than 5 percent by dry weight passing the U.S. Standard No. 200 sieve. The percentage of fines can be increased to 12 percent if the fill is placed during dry weather and provided the fill material is moisture conditioned, as necessary, for proper compaction. The material should be placed in lifts with a maximum uncompacted thickness of 12 inches and compacted to not less than 95 percent of the maximum dry density, as determined by ASTM D1 557. During the wet season or when wet subgrade conditions exist, the initial lift should have a maximum thickness of 15 inches and G EO DESIG N_ 8 SKB-15-01:021819 should be compacted by rolling with a smooth-drum roller without the use of vibratory action. Special conditions apply to wall backfill as described in the "Permanent Retaining Structures" section. 6.8.3 Trench Backfill Trench backfill placed beneath, adjacent to, and for at least 12 inches above utility lines (i.e., the pipe zone) should consist of well-graded granular material with a maximum particle size of 1%2 inches and less than 10 percent by dry weight passing the U.S. Standard No. 200 sieve. The pipe zone backfill should be compacted to at least 90 percent of the maximum dry density, as determined byASTM D1557, or as required by the pipe manufacturer or local building department. Within pavement areas and building pads, the upper portion of the trench backfill should consist of well-graded granular material, with a maximum particle size of 2% inches. Trench backfill should be compacted to at least 90 percent of the maximum dry density, as determined by ASTM D1557, or as required by the pipe manufacturer or local building department. The upper 3 feet of the trench backfill should be compacted to at least 95 percent of the maximum dry density, as determined byASTM D1557. 6.8.4 Stabilization Material Material used to stabilize staging areas, haul roads, and utility trench subgrade should consist of pit- or quarry-run rock, crushed rock, or crushed gravel and sand with a maximum particle size of 4 inches; should have less than 5 percent by dry weight passing the U.S. Standard No. 4 sieve; and should have at least two mechanically fractured faces. The material should be free of organic matter and other deleterious material. The stabilization material should be placed in one lift and compacted to a well-keyed, firm condition. 6.8.5 Drain Rock Drain rock should consist of angular, granular, open-graded material with a maximum particle size of 2 inches. The material should be free of roots, organic matter, and other unsuitable materials; have less than 2 percent by dry weight passing the U.S. Standard No. 200 sieve (washed analysis); and have at least two mechanically fractured faces. Drain rock should be compacted to a well-keyed, firm condition. 6.8.6 Floor Slab Base Rock Imported granular material placed beneath building floor slabs should be clean, crushed rock or crushed gravel and sand that is fairly well graded between coarse and fine. The granular material should have a maximum particle size of 1Y2 inches, less than 5 percent by dry weight passing a U.S. Standard No. 200 sieve, and at least two mechanically fractured faces. The imported granular material should be placed in one lift and compacted to not less than 95 percent of the maximum dry density, as determined byASTM D1557. 6.8.7 Retaining Wall Select Backfill Backfill material placed behind retaining walls and extending a horizontal distance of Y2H, where H is the height of the retaining wall, should consist of imported granular material. The backfill GEQDESIGN? 9 SKB-15-01:021819 should be placed and compacted as recommended for structural fill, with the exception of backfill placed immediately adjacent to walls. Backfill adjacent to walls should be compacted to a lesser standard to reduce the potential for generation of excessive pressure on the walls. Backfill located within a horizontal distance of 3 feet from the retaining walls should be compacted to approximately 90 percent of the maximum dry density, as determined by ASTM D1 557. Backfill placed within 3 feet of the wall should be compacted in lifts less than 6 inches thick using hand- operated tamping equipment (such as a jumping jack or vibratory plate compactor). If flatwork (slabs, sidewalk, or pavement) will be placed adjacent to the wall, we recommend that the upper 2 feet of fill be compacted to 95 percent of the maximum dry density, as determined by ASTM D1 557. 6.8.8 Recycled Concrete Recycled concrete can be used for structural fill provided the concrete is broken to a maximum particle size of 3 inches. This material can be used as trench backfill if it meets the requirements for imported granular material, which would require a smaller maximum particle size. The material should be placed in lifts with a maximum uncompacted thickness of 12 inches and compacted to not less than 95 percent of the maximum dry density as determined by ASTM D1 557. 6.8.9 Geotextile Fabric 6.89.1 Subgrade Geotextile The subgrade geotextile should meet the specifications provided in OSSC Table 02320-4 - Geotextile Property Values for Subgrade Geotextile (Separation). The geotextile should be installed in conformance with OSSC 00350 (Geosynthetic Installation). A minimum initial aggregate base lift of 6 inches is required over geotextiles. All drainage aggregate and stabilization material should be underlain by a subgrade geotextile. Geotextile is not required where stabilization material is used at the base of utility trenches. 6.8.9.2 Drainage Geotextile Drainage geotextile should meet the specifications provided in OSSC Table 02320-1 - Geotextile Property Values for Drainage Geotextile. The geotextile should be installed in conformance with OSSC 00350 (Geosynthetic Installation). A minimum initial aggregate base lift of 6 inches is required over geotextiles. 6.8.10 Soil Amendment with Cement 6.8.10.1 General As an alternative to the use of imported granular material for wet weather structural fill, an experienced contractor may be able to amend the on-site soil with portland cement to obtain suitable support properties. Depending on the grade and location, cobbles and boulders in the underlying gravel could be present in the subgrade. Cobbles and boulders can damage cement tilling equipment and when encountered may require removal for cement treatment. Successful use of soil amendment depends on the use of correct mixing techniques, soil moisture content, and amendment quantities. Soil amending should be conducted in accordance with the specifications provided in OSSC 00344 (Treated Subgrade). The amount of cement used during treatment should be based on an assumed soil dry unit weight of 110 pcf. G EODESIGN= 10 SKB-15-01:021819 6.8.10.2 Subbase Stabilization Specific recommendations based on exposed site conditions for soil amending can be provided if necessary. However, for preliminary design purposes, we recommend a target strength for cement-amended subgrade for building and pavement subbase (below aggregate base) soil of 100 psi. The amount of cement used to achieve this target generally varies with moisture content and soil type. It is difficult to predict field performance of soil to cement amendment due to variability in soil response, and we recommend laboratory testing to confirm expectations. Generally, 5 percent cement by weight of dry soil can be used when the soil moisture content does not exceed approximately 20 percent. If the soil moisture content is in the range of 25 to 35 percent, 6 to 8 percent by weight of dry soil is recommended. The amount of cement added to the soil may need to be adjusted based on field observations and performance. Moreover, depending on the time of year and moisture content levels during amendment, water may need to be applied during tilling to appropriately condition the soil moisture content. For building and pavement subbase, we recommend assuming a minimum cement ratio of 6 percent(by dry weight). If the soil moistures are in excess of 30 percent, a cement ratio of 7 percent may be needed. Because of the higher organic content, we recommend using a cement ratio of 8 percent when stabilizing topsoil zone material for building and pavement subbase and anticipate that the cement will need to be applied in two 4 percent applications followed by multiple tilling passes with each application. We recommend cement-amending equipment be equipped with balloon tires to reduce rutting and disturbance of the fine-grained soil. A static sheepsfoot or segmented pad roller with a minimum static weight of 40,000 pounds should be used for initial compaction of the fine- grained soil. A smooth-drum roller with a minimum applied linear force of 700 pounds per inch should be used for final compaction. The amended soil should be compacted to at least 92 percent of the achievable dry density at the moisture content of the material, as defined in ASTM D1 557. A minimum curing of four days is required between treatment and construction traffic access. Construction traffic should not be allowed on unprotected, cement-amended subgrade. To protect the cement-treated surfaces from abrasion or damage, the finished surface should be covered with 4 to 6 inches of imported granular material. Treatment depths for building/pavement, haul roads, and staging areas are typically on the order of 12, 16, and 12 inches, respectively. The crushed rock typically becomes contaminated with soil during construction. Contaminated base rock should be removed and replaced with clean rock in pavement areas. The actual thickness of the amended material and imported granular material for haul roads and staging areas will depend on the anticipated traffic, as well as the contractor's means and methods and, accordingly, should be the contractor's responsibility. Cement amending should not be attempted when air temperature is below 40 degrees Fahrenheit or during moderate to heavy precipitation. Cement should not be placed when the ground surface is saturated or standing water exists. GEODESIGN= 11 SKB-15-01:021819 6.8. 10.3 Other Considerations Portland cement-amended soil is hard and has low permeability. This soil does not drain well and it is not suitable for planting. Future planted areas should not be cement amended, if practical, or accommodations should be made for drainage and planting. Moreover, cement amending soil within building areas must be done carefully to avoid trapping water under floor slabs. We should be contacted if this approach is considered. Cement amendment should not be used if runoff during construction cannot be directed away from adjacent wetlands (if any). 6.8.11 AC 6.8.11.1 General The AC should be Level 2, %-inch, dense ACP according to OSSC 00744 (Asphalt Concrete Pavement) and compacted to 91 percent of the theoretical maximum density of the mix, as determined by AASHTO T 209. The minimum and maximum lift thickness is 2.0 and 3.0 inches, respectively, for%z-inch ACP. Asphalt binder should be performance graded and conform to PG 64-22 or better. 6.8.11.2 Cold Weather Paving Considerations In general, AC paving is not recommended during cold weather(temperatures less than 40 degrees Fahrenheit). Compacting under these conditions can result in low compaction and premature pavement distress Each AC mix design has a recommended compaction temperature range that is specific for the particular AC binder used. In colder temperatures, it is more difficult to maintain the temperature of the AC mix as it can lose heat while stored in the delivery truck, as it is placed, and in the time between placement and compaction. In Oregon, the AC surface temperature during paving should be at least 40 degrees Fahrenheit for lift thickness greater than 2.5 inches and at least 50 degrees Fahrenheit for lift thickness between 2.0 and 2.5 inches. If paving activities must take place during cold-weather construction as defined above, the project team should be consulted and a site meeting should be held to discuss ways to lessen low compaction risks. 6.9 PERMANENT CUT AND FILL SLOPES Permanent cut and fill slopes in the site soil should be inclined no steeper than 2H:1V. Buildings, access roads, and pavement should be set back a minimum of 5 feet from the crest of any such slopes. 6. 10 PAVEMENTS Pavement should be installed on subgrade prepared in conformance with the "Site Preparation" and "Materials" sections. Our pavement recommendations are based on the following assumptions: • Resilient moduli of 3,500 psi and 20,000 psi were assumed for the subgrade and aggregate base, respectively • A pavement design life of 20 years • Initial and terminal serviceability indices of 4.2 and 2.5, respectively GEODESIGN= 12 SKB-15-01:021819 • Reliability of 85 percent and standard deviation of 0.5 • Structural coefficients of 0.42 and 0.10 for the AC and aggregate base, respectively • No growth • Heavy traffic is limited to garbage trucks and occasional delivery vehicles. If any of these assumptions vary from project design values, our office should be contacted with the appropriate information so that the pavement designs can be revised. Standard pavements sections should be designed in accordance with Table 3. Table 3. Recommended Standard Pavement Sections Traffic Levels AC Aggregate Base (inches) (inches) Car Parking Areas 2.5 8.0 Drive Aisles for All Traffic 3.5 10 Alternative pavement sections may be possible using cement-amended subgrade. However, if grading results in low areas that extend close to the gravel material, cement amendment will not be an option because of the likely damage to the tiller used to mix the soil-cement. If the subgrade is cement amended to the thicknesses indicated below and the amended soil achieves a seven-day unconfined compressive strength of at least 100 psi, the pavements can be constructed as recommended in Table 4. Table 4. Recommended Pavement Sections with Cement Amendment Traffic Levels AC Aggregate Base Cement Amendment' (inches) (inches) (inches) Car Parking Areas 2.5 4.0 12.0 Drive Aisles for All Traffic 3.5 4.0 12.0 1. Assumes a minimum seven-day unconfined compressive strength of 100 psi. All thicknesses are intended to be the minimum acceptable. The aggregate thicknesses are based on post-construction traffic loading and are not intended to support construction traffic. Increased thickness of aggregate base may be required, particularly in the wet season (see "Construction Considerations" section). The AC, aggregate base, and cement amendment should meet the requirements outlined in the "Materials" section. Aggregate base contaminated during construction should be removed and replaced with material meeting the gradation requirements. Construction traffic should not be allowed on new pavements. If construction traffic is to be allowed on newly constructed road sections, an allowance for this additional traffic will need to be made in the design pavement section. EO DES IGN= 13 SKB-15-01:021819 7.0 FOUNDATION SUPPORT RECOMMENDATIONS Building loads were not known at the time of this report. Based on explorations, laboratory testing, and analysis, columns with maximum loads of 400 kips can be supported by conventional spread footings underlain 2-foot thick granular pads. Columns with loads greater than 400 kips should be supported by conventional spread footings bearing on rammed aggregate piers. Our recommendations for use in design and construction of foundations are presented below. 7. 1 CONVENTIONAL SPREAD FOOTINGS Spread footings are feasible if column loads are less than 400 kips. Conventional spread footings should be underlain by 2-foot-thick granular pads bearing on undisturbed native silt soil. Footings should not be supported on undocumented fill. Granular pads should extend 6 inches beyond the margins of the footings for every foot excavated below the base grade of the footings. Granular pads should consist of imported granular material, as defined in the "Materials" section. The imported granular material should be compacted to not less than 95 percent of the maximum dry density, as determined by ASTM D1557, or, as determined by one of our geotechnical staff, until well keyed. We recommend that a member of our geotechnical staff observe the prepared footing subgrade. 7.1.1 Bearing Capacity We recommend that spread footings be sized based on an allowable bearing pressure of 2,500 psf. This is a net bearing pressure; the weight of the footing and overlying backfill can be ignored in calculating footing sizes. The recommended allowable bearing pressure applies to the total of dead and long-term live loads and may be increased by one-third for short-term loads, such as those resulting from wind or seismic forces. We recommend that isolated column and continuous wall footings have minimum widths of 24 and 18 inches, respectively. The bottom of exterior footings should be founded at least 18 inches below the lowest adjacent grade. Interior footings should be founded at least 12 inches below the base of the floor slab. 7.1.2 Settlement We anticipate that total post-construction settlement will be less than 1 inch for shallow foundations designed in accordance with the recommendations provided above. Differential settlement between similarly loaded footings is expected to be less than Yz inch. 7.1.3 Lateral Resistance Lateral loads on footings can be resisted by the passive earth pressure on the sides of the structure and by friction on the base of the footings. Our analysis indicates that the available passive earth pressure for footings confined by native soil and structural fill is 350 pcf, modeled as an equivalent fluid pressure. Adjacent floor slabs, pavements, or the upper 12-inch depth of adjacent unpaved areas should not be considered when calculating passive resistance. A coefficient of friction equal to 0.45 may be used when calculating resistance to sliding for footings in direct contact with granular pads. GEODESIGN? 14 SKB-15-01:021819 7.2 SPREAD FOOTINGS SUPPORTED ON RAMMED AGGREGATE PIERS Rammed aggregate piers consist of compacted aggregate columns that reinforce and improve the soil. These systems are proprietary and designed and constructed by a specialty contractor. Conventional spread foundations are placed over the completed rammed aggregate piers. Installing the aggregate piers may require drilling through perched groundwater zones. If perched groundwater is encountered, casing might be required to advance the auger excavations for the aggregate piers. An allowable bearing pressure between 4,000 and 6,000 psf is typically provided by the designers of rammed aggregate piers. A one-third increase in allowable bearing pressure is also typical for such systems when resisting short-term loads such as wind and seismic forces. Shallow foundations bearing on rammed aggregate piers should experience post-construction settlement of less than 1 inch. Differential settlement of up to one-half of the total settlement magnitude can be expected between adjacent footings with similar loads. We expect settlement will occur during construction as loads are applied. Lateral loads for spread footings on rammed aggregate piers can be designed as described "Conventional Spread Footings" section. 7.3 SLABS ON GRADE A modulus of subgrade reaction of 100 pci can be used for design of floor slabs that bear on the native silty soil that overlies the gravel. This assumes that all of the undocumented fill is removed from the subgrade to expose undisturbed native soil. Groundwater will be present above the planned floor slab and under slab drains or a floor slab designed to resist uplift forces will be required as described in the "Groundwater" section (Section 10.0). We recommend that the floor slab be supported on at least 6 inches of imported granular material to aid as a capillary break and to provide uniform support. The imported granular material should be placed and compacted as previously recommended for aggregate base. Vapor barriers beneath floor slabs are typically required by flooring manufactures to maintain the warranty on their products. In our experience, adequate performance of floor adhesives can be achieved by using a clean base rock (less than 5 percent fines) beneath the floor slab with no vapor barrier. In fact, vapor barriers can frequently cause moisture problems by trapping water beneath the floor slab that is introduced during construction. If a vapor barrier is used, water should not be applied to the base rock prior to pouring the slab and the work should be completed during extended dry weather so that rainfall is not trapped on top of the vapor barrier. Selection and design of an appropriate vapor barrier, if needed, should be based on discussions among members of the design team. We can provide additional information to assist you with your decision. G EO DESI G N= 15 sK6-15-01.021819 8.0 PERMANENT RETAINING STRUCTURES Retaining structures and basement walls can be designed using the values presented on Figure 3. These values are based on the following assumptions: (1) the retained soil is level, (2) the retained soil is drained, and (3) the wall is less than 20 feet in height. Lateral pressures induced by surcharge loads can be computed using the methods presented on Figure 4. A vertical live load of 250 psf should be applied at the surface of the retained soil where walls retain roadways. If slopes are present behind walls, the equivalent fluid pressures on Figure 3 should be increased per Table 2. Basement walls that extend below groundwater and do not have back of wall drains should be designed to resist hydrostatic pressure as described the "Groundwater" section (Section 10.0). Seismic lateral forces can be calculated using a dynamic force equal to 7.5H2 pounds per linear foot of wall, where H is the wall height. The seismic force should be applied as a distributed load with the centroid located at 0.6H from the wall base. Footings for retaining walls should be designed as recommended in the "Foundation Support Recommendations" section. Drains should be provided behind retaining walls to prevent hydrostatic pressures from developing. 9.0 DRAINAGE CONSIDERATIONS 9.1 GENERAL We recommend roof drains be connected to a tightline leading to storm drain facilities. Pavement surfaces and open space areas should be sloped such that surface water runoff is collected and routed to suitable discharge points. We also recommend ground surfaces adjacent to the building be sloped to facilitate positive drainage away from the building. 9.2 INFILTRATION SYSTEMS Infiltration values are provided in the "Infiltration Testing" section. Infiltration rates at all depths across the site are negligible due to the presence of silty soil with minimal sand. Based on testing and the soil and groundwater conditions at the site, the infiltration rates at the site are inadequate for on-site disposal of stormwater. 10.0 GROUNDWATER Based on measurements at the site, groundwater will be above the planned finished floor slab. Based on these considerations, the design options for the basement floor slab (and retaining walls) are as follows: • Design the basement to be substantially impermeable to water and structurally designed to resist the hydrostatic pressure associated with the groundwater Table rising to a depth of 6 feet BGS. • Install drains behind basement walls and a subfloor dewatering system beneath the floor slab connected to a sump that discharges the water to the storm system. The wall drains should consist of a minimum 2-foot-wide column of drain rock wrapped in a non-woven geotextile such as Mirafi 140N. The subfloor drainage system should consist of 6-inch-diameter, perforated PVC pipe installed on maximum 20-foot centers across the basement footprint. G EO DESI G N? 16 SKB-15-01:021 81 9 The system should include perimeter perforated pipe installed on the interior of the perimeter foundations. All subfloor perforated piping should be installed so that the invert elevation of the pipe is at least 2 feet below the finished floor elevation. The slab should be underlain by at least 18 inches of drain rock, and the perforated pipe should be installed in minimum 18-inch-wide trenches and fully surrounded with 2-inch crushed drain rock. The drain rock should be separated from the slab and trench wall subgrade with a non-woven geotextile. The pipe should be sloped at a minimum 1/2 percent toward a sump and pump. 11.0 SEISMIC DESIGN CRITERIA We recommend that the building at the site be designed using the applicable provisions of the 201 5 IBC. Based on the results of our explorations, a classification of Site Class D can be used for the site. The seismic design criteria in accordance with the 201 5 IBC are summarized in Table 5. Table 5. IBC Seismic Design Parameters Parameter Short Period 1 Second MCE Spectral Acceleration S, = 0.980 g S, = 0.424 g Site Class D Site Coefficient Fa = 1.108 F.= 1 .576 Adjusted Spectral Acceleration SMS= 1.086 g SM, = 0.668 g Design Spectral Response Acceleration Parameters SD, = 0.724 g So, = 0.445 g 12.0 OBSERVATION OF CONSTRUCTION Satisfactory earthwork and foundation performance depends to a large degree on the quality of construction. Subsurface conditions observed during construction should be compared with those encountered during the subsurface explorations. Recognition of changed conditions often requires experience; therefore, qualified personnel should visit the site with sufficient frequency to detect whether subsurface conditions change significantly from those anticipated. In addition, sufficient observation of the contractor's activities is a key part of determining that the work is completed in accordance with the construction drawings and specifications. 13.0 LIMITATIONS We have prepared this report for use by ScanlanKemperBard and members of the design and construction teams for the proposed development. The data and report can be used for estimating purposes, but our report, conclusions, and interpretations should not be construed as a warranty of the subsurface conditions and are not applicable to other sites. G EO DESIG Nz 17 SKB-15-01 021819 Soil explorations indicate soil conditions only at specific locations and only to the depths penetrated. They do not necessarily reflect soil strata or water level variations that may exist between exploration locations. If subsurface conditions differing from those described are noted during the course of excavation and construction, re-evaluation will be necessary. The site development plans and design details were not finalized at the time this report was prepared. When the design has been finalized and if there are changes in the site grades or location, configuration, design loads, or type of construction, the conclusions and recommendations presented may not be applicable. If design changes are made, we should be retained to review our conclusions and recommendations and to provide a written evaluation or modification. The scope of our services does not include services related to construction safety precautions, and our recommendations are not intended to direct the contractor's methods, techniques, sequences, or procedures, except as specifically described in our report for consideration in design. Within the limitations of scope, schedule, and budget, our services have been executed in accordance with the generally accepted practices in this area at the time this report was prepared. No warranty or other conditions, express or implied, should be understood. ♦ ♦ ♦ We appreciate the opportunity to be of continued service to you. Please call if you have questions concerning this report or if we can provide additional services. Sincerely, GeoDesign, Inc. `��vO PROBES Arl O, ,,GVNEF, cS, , cr (ye Nick Paveglio P.E. • / Senior Associate Engineer DREG• , 6O 'AS N.PP`J&' EXPIRES: 12/31/20 Brett A. Shipton, P.E., G.E. Principal Engineer GEODESIGN= 18 5KB-15-01:021819 FIGURES Printed By:mmiller I Print Date:2/11/2019 11:42:45 AM File Name:J:\S-Z\SKB\SKB-15\SKB-15-01\Figures\CAD\5KB-15-01-DET02.dwg I Layout:FIGURE 4 Fes- X=mH Imo— x=mH POINT LOAD,Qp LINE LOAD,QL �_____, a STRIP LOAD,q Z=InH Z=nH i10111 ' 1 EV i W WI.Ille>11.11P.- H la H lir H IW w- vh oh IV ah % FOR m<0.4= FOR m<0.4= �\j� Qh=2�t ()4-SINE COS 2a) 4\ p = 0 28 t$ QL 0.2 n 3.14 O \ h H2 (0.16+ Y > h = H r? } �\ ` / , A/A/ ` /� (0.16+ i /,/Z `//... (i3 IN RADIANS) FOR m>0.4= FOR m>0.4= v Q 1.77rr2 n2 Q h = (nt2+n2)3 ph = L (.2nn H (m 4.+r2)2 LINE LOAD PARALLEL TO WALL STRIP LOAD PARALLEL TO WALL —t— x=mH gal' oh =oh CO52(1.1ro) NOTES: iof , 1. THESE GUIDELINES APPLY TO RIGID WALLS WITH POISSON'S RATIO ASSUMED TO BE 0.5 FOR BACKFILL MATERIALS. DISTRIBUTION OF HORIZONTAL PRESSURES 2. LATERAL PRESSURES FROM ANY COMBINATION OF ABOVE LOADS MAY BE DETERMINED BY THE PRINCIPLE OF VERTICAL POINT LOAD SUPERPOSITION. 3. VALUES IN THIS FIGURE ARE UNFACTORED. G EO DES IGN? SKB-15-01 SURCHARGE-INDUCED LATERAL EARTH PRESSURES 9450 SW Commerce Circle-Suite 300 Wilsonville OR 97070 FEBRUARY 2019 72ND AND DARTMOUTH DEVELOPMENT FIGURE 4 503.968.8787 www.geodesigninc.com TIGARD, OR APPENDIX A APPENDIX A FIELD EXPLORATIONS GENERAL We drilled four supplemental borings (B-1 through B-4) to further our understanding of subsurface conditions. The borings were drilled to depths between 31 .5 and 61 .5 feet BGS. Drilling services were provided by Western States Soil Conservation, Inc. of Hubbard, Oregon. The explorations were conducted with a drill rig using mud rotary and hollow-stem auger drilling techniques on January 15 and 16, 2019. The exploration logs are presented in this appendix. The exploration locations were located in the field pacing from survey existing site features. This information should be considered accurate only to the degree implied by the methods used. A member of our geology staff observed the exploration. We collected representative samples of the various soils encountered in the exploration for geotechnical laboratory testing. SOIL SAMPLING Soil samples were collected from the borings by conducting SPTs in general conformance with ASTM D1 586. The sampler was driven with a 140-pound, automatic-trip hammer free-falling 30 inches. The number of blows required to drive the sampler 1 foot, or as otherwise indicated, into the soil is shown adjacent to the sample symbols on the exploration logs. Disturbed samples were collected from the split barrel for subsequent classification and index testing. Relatively undisturbed samples were collected using a standard Shelby tube in general accordance with ASTM D1 587. Sampling methods and intervals are shown on the exploration logs. The average efficiency of the automatic SPT hammer used by Western States Soil Conservation, Inc. was reported to be 85.0 percent. The calibration testing results are presented at the end of this appendix. SOIL CLASSIFICATION The soil samples were classified in accordance with the "Exploration Key" (Table A-1) and "Soil Classification System" (Table A-2), which are presented in this appendix. The exploration logs indicate the depths at which the soil or its characteristics change, although the change actually could be gradual. If the change occurred between sample locations, the depth was interpreted. Classifications are shown on the exploration logs. LABORATORY TESTING CLASSIFICATION The soil samples were classified in the laboratory to confirm field classifications. The laboratory classifications are included on the exploration logs if those classifications differed from the field classifications. G EODESIGN= A-1 SKB-15-01:021819 ATTERBERG LIMITS The plastic limit and liquid limit (Atterberg limits) of select soil samples were determined in accordance with ASTM D4318. The Atterberg limits and the plasticity index were completed to aid in the classification of the soil. The test results are presented in this appendix. CONSOLIDATION TESTS Consolidation testing was performed on a select soil sample in general accordance with ASTM D2435. The test results are presented in this appendix. MOISTURE CONTENT We determined the natural moisture content of select soil samples in general accordance with ASTM D2216. The test results are presented in this appendix. PARTICLE-SIZE ANALYSIS Particle-size analysis was performed on select soil samples in general accordance with ASTM D1 140. This test determines of the amount of material finer than a 75-micrometer (No. 200) sieve expressed as a percentage of the dry weight of soil. The test results are presented in this appendix. GEODESIGN= A-2 SKB-15-01:021 81 9 SYMBOL SAMPLING DESCRIPTION RI Location of sample obtained in general accordance with ASTM D 1 586 Standard Penetration Test with recovery II Location of sample obtained using thin-wall Shelby tube or Geoprobe® sampler in general accordance with ASTM D 1 587 with recovery Location of sample obtained using Dames & Moore sampler and 300-pound hammer or pushed with recovery I Location of sample obtained using Dames & Moore sampler and 140-pound hammer or pushed with recovery N Location of sample obtained using 3-inch-O.D. California split-spoon sampler and 140-pound hammer NLocation of grab sample Graphic Log of Soil and Rock Types w . • Observed contact between soil or 11 Rock coring interval rock units(at depth indicated) SZ Water level during drilling Inferred contact between soil or rock units(at approximate depths indicated) i Water level taken on date shown . — — GEOTECHNICAL TESTING EXPLANATIONS ATT Atterberg Limits P Pushed Sample CBR California Bearing Ratio PP Pocket Penetrometer CON Consolidation P200 Percent Passing U.S. Standard No. 200 DD Dry Density Sieve DS Direct Shear RES Resilient Modulus HYD Hydrometer Gradation SIEV Sieve Gradation MC Moisture Content TOR Torvane MD Moisture-Density Relationship UC Unconfined Compressive Strength NP Nonplastic VS Vane Shear OC Organic Content kPa Kilopascal ENVIRONMENTAL TESTING EXPLANATIONS CA Sample Submitted for Chemical Analysis ND Not Detected P Pushed Sample NS No Visible Sheen PID Photoionization Detector Headspace SS Slight Sheen Analysis MS Moderate Sheen ppm Parts per Million HS Heavy Sheen G EODESIGNU 9450 5W Commerce CI,cle-Suite 300 EXPLORATION KEY TABLE A-1 Wilsonville OR 97070 503 968 8737 www.geodes igninc.com I RELATIVE DENSITY - COARSE-GRAINED SOIL Relative Density Standard Penetration Dames& Moore Sampler Dames& Moore Sampler Resistance (140-pound hammer) (300-pound hammer) Very Loose 0 -4 0 - 11 0-4 Loose 4 - 10 11 -26 4 - 10 Medium Dense 10 - 30 26-74 10 - 30 Dense 30 - 50 74- 120 30 -47 Very Dense More than 50 More than 120 More than 47 CONSISTENCY - FINE-GRAINED SOIL Standard Dames& Moore Dames& Moore Sampler Unconfined Compressive Consistency Penetration Sampler (300-pound hammer) Strength (tsf) Resistance (140-pound hammer) Very Soft Less than 2 Less than 3 Less than 2 Less than 0.25 Soft 2 - 4 3 -6 2 - 5 0.25 -0.50 Medium Stiff 4- 8 6 - 12 5 - 9 0.50 - 1.0 Stiff 8 - 15 12 -25 9 - 19 1.0 - 2.0 Very Stiff 15 - 30 25 -65 19 - 31 2.0-4.0 Hard More than 30 More than 65 _ More than 31 More than 4.0 PRIMARY SOIL DIVISIONS GROUP SYMBOL GROUP NAME CLEAN GRAVEL GW or GP GRAVEL GRAVEL (< 5%fines) (more than 50%of GRAVEL WITH FINES GW-GM or GP-GM GRAVEL with silt (>_ 5%and <_ 12%fines) GW-GC or GP-GC GRAVEL with clay coarse fraction COARSE- retained on GRAVEL WITH FINES GM silty GRAVEL GRAINED SOIL No. 4 sieve) GC clayey GRAVEL (> 12%fines) GC-GM silty, clayey GRAVEL (more than 50% CLEAN SAND retained on SAND (<5%fines) SW or SP SAND No. 200 sieve) SAND WITH FINES SW-SM or SP-SM SAND with silt (50%or more of > 5%and <_ 12%fines coarse fraction (- ) SW-SC or SP-SC SAND with clay passing SM silty SAND No. 4 sieve) SAND WITH FINES SC clayey SAND (> 12%fines) SC-SM silty, clayey SAND ML SILT FINE-GRAINED CL CLAY SOIL Liquid limit less than 50 CL-ML silty CLAY (50%or more SILT AND CLAY OL ORGANIC SILT or ORGANIC CLAY passing MH SILT No. 200 sieve) Liquid limit 50 or greater CH CLAY OH ORGANIC SILT or ORGANIC CLAY HIGHLY ORGANIC SOIL PT PEAT MOISTURE ADDITIONAL CONSTITUENTS CLASSIFICATION Secondary granular components or other materials Term Field Test such as organics, man-made debris, etc. Silt and Clay In: Sand and Gravel In: very low moisture, Percent Fine-Grained Coarse- Percent Fine-Grained Coarse- dry dry to touch Soil Grained Soil Soil Grained Soil damp, without < 5 trace trace < 5 trace trace moist visible moisture 5 - 12 minor with 5 - 15 minor minor visible free water, > 12 some silty/clayey 15 - 30 with with wet usually saturated ; ,; u , , ;: x�'i > 30 sandy/gravelly Indicate% G EODESIGN o SOIL CLASSIFICATION SYSTEM TABLE A-2 Wilsonville OR 97070 503.968.8787 www.9eodesignlnc.com Z o = z w r BLOW COUNT INSTALLATION AND DEPTH L.) Q - •MOISTURE CONTENT% COMMENTS = MATERIAL DESCRIPTION >w 1— g FEET a w t++ w Q RQD% CORE REC% I- an 0 U 0 50 100 Medium stiff, brown with gray mottled SILT(ML), minor sand; moist (2-inch- thick root zone). Il 5 medium stiff to stiff at 5.0 feet 1111 medium stiff, brown at 7.5 feet F o 5 Infiltration test:—0.0 inches P200I r • per hour at 10.0 feet. P200-89% Very soft to soft, brown SILT (ML), minor 13.5 sand; wet. 15— ATT ` • LL-NP gray at 16.0 feet PL=NP 20 very soft at 20.0 feet IT o _ • DD=83 pcf very soft to soft; moist to wet at 24.0 CON {`F. 25— feet _ r medium stiff; moist at 26,0 feet Stiff, orange-brown SILT(ML), trace 28.5 sand; moist. 30— Y 12 m _ N W i 35— very stiff at 35.0 feet 42 U z - U ❑ U 40 0 50 100 m DRILLED BY:Western States Soil Conservation,Inc. LOGGED BY:R.Kistler COMPLETED:01/15/19 9 Y BORING METHOD:mud rotary and hollow-stern auger(see document text) BORING BIT DIAMETER:6 inches/3 7/8 inches ut zG EODESIGNZ SKB-15-01 BORING B-1 r° 94505W Commerce Circle-Suite 300 m Wilsonville OR97070 FEBRUARY 2019 72ND AND DARTMOUTH DEVELOPMENT 503968.8787 www.geodesigninc.cam TIGARD, OR FIGURE A-1 z a = v w BLOW COUNT INSTALLATION AND DEPTH u Q 0- z a •MOISTURE CONTENT% COMMENTS FEET d MATERIAL DESCRIPTION w O I- 2 w < RQD% CORE REC% —40 u a 50 100 (continued from previous page) r Exploration completed at a depth of 41.5 Surface elevation was not 4 .5 feet. measured at the time of exploration. Hammer efficiency factor is 85.0 45— percent. 50— 55— 60— 65— I— Y 70 Y 0 1 N W _ a 0 F Z a 75— t- 0 u z u_ 0 0 2 _ V 80 d 0 50 100 DRILLED BY:Western States Soil Conservation,Inc. LOGGED BY:R.Kistler COMPLETED:01/15/19 0 ro BORING METHOD:mud rotary and hollow-stem auger(see document text) BORING BIT DIAMETER:6 inchesl37/8 inches g BORING B-1 Z G EODESIGN? SKB 15-01 (continued) m0 9450SW Commerce Circle-Suite 300 72ND AND DARTMOUTH DEVELOPMENT WilsonVilk OR97070 FEBRUARY 2019 503.968.8787 vetw.geodesIgnInc.com TIGARD, OR FIGURE A-1 Z o w BLOW COUNT INSTALLATION AND DEPTH u Z - •MOISTURE CONTENT% COMMENTS = MATERIAL DESCRIPTION >w I— g FEET a w w QMT1RQD% 1,77J CORE REC% w vl u (.7 0 50 100 Medium stiff, brown SILT(ML), minor sand; moist(2-inch-thick root zone). • 5 stiff at 5.0 feet11 r medium stiff at 7.5 feet ATT � LL=33% PL-27% m 10— v` -o w 6 15— moist to wet at 1 5.0 feet I 6 Infiltration test:—0.0 inches P200 ` • per hour at 15.0 feet. gray at 16.0 feet P200=95% 20— moist at 20.0 feet • s Very stiff, brown with gray mottled SILT 23 5 (ML), trace sand; moist. zs— `7 H 30 h `6 rn 0 Exploration completed at a depth of 31 5 Surface elevation was not ry measured at the time of 31.5 feet. exploration. Hammer efficiency factor is 85.0 percent. o. 35 0 - 0 u z u 0 0 w u 40 0 50 100 m DRILLED BY:Western States Soil Conservation,Inc. LOGGED BY:R.Kistler COMPLETED:01M6119 0 N ,n BORING METHOD'.mud rotary and hollow-stem auger(see document text) BORING BIT DIAMETER:6 inches/3 7/8 inches Y GEO DES IGNz 5KB-15-01 BORING B-2 ▪ 9450 SW Commerce Circle-suite Soo 72ND AND DARTMOUTH DEVELOPMENT m Wilsonville 503.968.8787w+mv.geodesigninc.com FEBRUARY 2019 TIGARD, OR FIGURE A-2 Z o O= (.2 w A BLOW COUNT INSTALLATION AND DEPTH ~Li Z —I COMMENTS FEET a MATERIAL DESCRIPTION W0 w N •MOISTURE CONTENT tl w < lTTI RQD% V/J CORE REC% w I— to I..) 0 50 100 ° Medium stiff to stiff, brown SILT (ML), - trace sand; moist(2-inch-thick root zone). Ill 118i - — medium stiff at 5.0 feet I r E Ai 10— soft to medium stiff; moist to wet at 10.0 feet 15— medium stiff; moist at 1 5.0 feet [ ` gray at 16.0 feet Medium stiff, brown-orange SILT (ML), 18.5 trace sand; moist. 20_ Infiltration test:-0.0 inches - P200 I 1 • per hour at 20.0 feet. P200=86% zs stiff to very stiff at 25.0 feet ATT rs .• LL-30% PL=25% 5' Y 30— very stiff at 30.0 feet 6 Ill A Exploration completed at a depth of 31 5 Surface elevation was not 31.5 feet. measured at the time of ui exploration. F O Hammer efficiency factor is 85.0 z percent. 2 35— H 0 u Z u - 0 0 u, u u 40 0 50 100 v m DRILLED BY:Western States Soil Conservation,Inc. LOGGED BY:R.Kistler COMPLETED:01/15/19 0 Y BORING METHOD:mud rotary and hollow-stem auger(see document text) BORING BIT DIAMETER:6 inches/3 7/8 inches v. G EODESIGN`i SKB-15-01 BORING B-3 9450 SW Commerce Circle-Suite 300 m Wilsonville OR97070 FEBRUARY 2019 72ND AND DARTMOUTH DEVELOPMENT FIGURE A-3 503.968.8787 wnwgeodesigninc.com TIGARD, OR Z • = z Laslow COUNT INSTALLATION AND DEPTH = a •MOISTURE CONTENT% MATERIAL DESCRIPTION >i'" I— 2 COMMENTS FEET nt w ¢ 1TTT1 RQD% 77j CORE REC% Lo F- 0 50 100 —0 Flush-mount Medium stiff, brown-gray with orange monument with 1.5 mottled SILT(ML), trace sand; moist. �a / feet of concrete backfill 1-inch Schude 40 5_ PVC well casing 111 • Cement-bentonite 10 brown-gray with dark brown mottles at 10.0 feet 5 - Infiltration test:-0.0 Medium stiff, orange-brown SILT (ML), 15.0 4inches per hour at P200 A • 15.0 feet. trace sand; moist. P200-97% • 20 gray-brown with orange mottles at 20.0 11 feet 25— ' Vibrating wire gray brown with black mottles at 25.0 #1 piezometer feet #1809552 set at 25.0 feet • • • 30 stiff to very stiff at 30.0 feet30 m N cL W 0 z z • ss— stiff at 35.0 feet rz a z - a a u • 40 0 50 100 r73 DRILLED BY:Western States Soil Conservation,Inc. LOGGED BY:L.Gose COMPLETED:01 16/19 0 BORING METHOD:mud rotary and hollow-stem auger(see document text) BC RI NC BIT DIAMETER:6 inches/37/8 inches V1 • GEODESIGN? 5KB-15-01 BORING B-4 9450 SW Commerce Circle-Suite 300 72ND AND DARTMOUTH DEVELOPMENT 503.968.67i87m11 FIGURE A-4 uw,w.geodesigninc.com FEBRUARY 2019 TIGARD, OR • ' 0= z w ♦BLOW COUNT INSTALLATION AND DEPTH = MATERIAL DESCRIPTION j F •MOISTURE CONTENT% COMMENTS FEET w w Q RQD% 11 COREREC% w I v) —40 0 s0 100 (continued from previous page) 2 as light gray at 45.0 feet F 2 so= very stiff at 50.0 feet 429 ss— hard, light green at 55.0 feet 51 ao— dark green at 60.0 feet 439 Exploration completed at a depth of 61.5 Surface elevation was 61.5 feet. not measured at the time of exploration. Hammer efficiency factor is 85.0 65— percent. 70 m _ W H Q F Z a 75— r- ❑ u z u ❑ u 80 0 50 100 DRILLED BY:Western States Soil Conservation,Inc. LOGGED BY:L.Gose COMPLETED:01/16/19 0 BORING METHOD:mud rotary and hollow-stern auger(see document text) BORING BIT DIAMETER:6 inches/3 7/8 inches ut GErDEsi,N? SKB-15-01 BORING B-4 (continued) 9450 SW Commerce Circle-Suite 300 Wilsonvilk OR97070 FEBRUARY 2019 72ND AND DARTMOUTH DEVELOPMENT FIGURE A-4 503,9653787 w+mv.geodesigninccom TIGARD, OR 60 50 CH or OH "A" LINE w 40 >- I— u 30 CL or OL 20 - 10 MH or OH CL-ML ♦m ML or OL 0 0 10 20 30 40 50 60 70 80 90 100 110 LIQUID LIMIT 2 EXPLORATION SAMPLE DEPTH MOISTURE CONTENT KEY NUMBER (FEET) (PERCENT) LIQUID LIMIT PLASTIC LIMIT PLASTICITY INDEX a • B-1 15.0 36 NP NP NP ❑ 0. m B-2 7.5 32 33 27 6 o A B-3 25.0 28 30 25 5 u z ❑ 0 w u u m 0 th Y N n N G EODESIGN? SKB-1 5-01 ATTERBERG LIMITS TEST RESULTS 9 W 450SW Commerce Circle-Suite 300 72ND AND DARTMOUTH DEVELOPMENT LaiWilsonville OR 97070 FEBRUARY 2019 FIGURE A-5 Q503.968.8787 www.geodesigninc.com TIGARD, OR o• • 2 4 6 H 8 re W '.. W 0- 10 Z_ vv 12 14 16 18 20 100 1 ,000 10,000 100,000 b STRESS (PSF) C- a KEY EXPLORATION SAMPLE DEPTH MOISTURE CONTENT DRY DENSITY NUMBER (FEET) (PERCENT) (PCF) g • B-1 23.0 36 83 s V O th N 0 O 0 GEoDEsicNz SKB-15-01 CONSOLIDATION TEST RESULTS 0 9450 5W Commerce❑rcie•Suite 300 72ND AND DARTMOUTH DEVELOPMENT Wilsonville OR97070 FEBRUARY 2019 FIGURE A-6 0 503.958.8767 www.geodeslgninc.com TIGARD, OR SAMPLE INFORMATION SIEVE ATTERBERG LIMITS MOISTURE DRY EXPLORATION SAMPLE ELEVATION CONTENT DENSITY GRAVEL SAND P200 LIQUID PLASTIC PLASTICITY NUMBER DEPTH (FEET) (PERCENT) (PCF) (PERCENT) (PERCENT) (PERCENT) LIMIT LIMIT INDEX (FEET) B-1 5.0 33 B-1 10.0 35 89 B-1 15.0 36 NP NP NP B-1 23.0 36 83 B-2 2.5 30 B-2 7.5 32 33 27 6 B-2 15.0 35 95 B-3 10.0 35 B-3 20.0 26 86 B-3 25.0 28 30 25 5 B-4 5.0 33 B-4 15.0 32 97 N ul 0 2 2 0. 0 I- 0 u 2 a 0 O u s u m 0 co U. G EODESIGN? SKB-15-01 SUMMARY OF LABORATORY DATA 9450 SW Commerce Circle-Suite 300 72ND AND DARTMOUTH DEVELOPMENT FIGURE A-7 m Wilsonville OR 97070 FEBRUARY 2019 c 503.968.87137 www.geodesigninccom TIGARD,OR Pile Dynamics, Inc. RIG#7 SPT Analyzer Results PDA-S Ver.2017.22-Printed: 1/412019 Summary of SPT Test Results Project:WSSC-8-04,Test Date: 1 2/2 712 0 1 8 EMX: Maximum Energy ETR: Energy Transfer Ratio-Rated Start Final N N60 Average Average Depth Depth Value Value EMX ETR ft ft ft-lb % 25.00 26.50 0 0 0.00 0.0 30.00 31.50 0 0 0.00 0.0 35.00 36.50 0 0 0.00 0.0 40.00 41.50 31 43 297.64 85.0 Overall Average Values: 297.64 85.0 Standard Deviation: 3.78 1.1 Overall Maximum Value: 303.37 86.7 Overall Minimum Value: 289.04 82.6 APPENDIX B APPENDIX B PREVIOUS EXPLORATIONS The logs and results of laboratory testing for four borings and five test pits completed at the site by Geotech Solutions in 2008 are presented in this appendix. The locations of the explorations are shown on Figure 2. G EODESIGN= B-1 SKB-15-01:021819 • Soil and Rock Description Samples and Data 0ft— w= moisture content ya= dry unit weight N60= SPT blowcount *= D&M Sampler with 300 pound hammer. Medium stiff, brown SILT; moist. © w=36% 10— -with trace fine sand. w=34% - becomes soft. 111 w=37% P:oo=93% =9 I pc( Direct Shear 20— - becomes gray; moist to wet. w=35% - becomes medium stiff and without trace sand. 111 w=35% 30— w=35% Stiff, orange-brown, SILT with occasional weathered basalt nodules; moist. w=31% 40— - becomes very stiff. w=32% Boring completed at 41.5 feet. otuhh BORING B- I tionS Inc! Norwest-07-0I-gi2 Soil and Rock Description Samples and Data 0ft— w= moisture content Monument �+ yd=dry unit weight Concrete = SPT blowcount N60 *= D&M Sampler with 300 pound hammer. Bentonite Chips Stiff, brown SILT; moist. w=40% Water level at 8.3 feet on March 5,2008 10— - becomes medium stiff. © w=35% Sand Backfill becomes soft with gray mottling. • w=34% Screened Piezometer Casing 20— - becomes gray; medium plasticity. w=34% yd=93 pcf Direct Shear - becomes medium stiff. w=28% rya=94 pcf Stiff, orange-brown, SILT; moist. ® w=34% r•r•r•r .1.1.1• r•r.r.r M1r1r:r:r 1.1.1.1. - Liry�y�ti� ti�1r{r'•r • .r.r.J•J _ 1ryr:rtr 1.1.1.1• r•r•rY — - becomes very stiff with trace clay and occasional weathered basalt nodules. ® w=23% L.1.1.1. r•r•r•r r•r•r•r 1r~r:r:r vr•r•r M1•1.1.1• 1.1.1.1• - r.r•r•r Y1.1.1. r.r•r•J 1.1.1.1• 1:1i1iy� r•r•r•r M1.1.4•L• 40— w=29% }J}+{ J BORING B-2 G of U l ions Inc! Norwest-07-01-gi2 Soil and Rock Description Samples and Data 40 ft- 1. t w= moisture content 1.1.1•Y �.r•r•r•r Ya=dry unit weight 1.1.1.1• r•r•f•r•1 N,=SPT blowcount D&M Sampler with *_ 300 pound hammer. hr:r~r~r J:r�r~f~f hrir1rSr 31 w=26% +. i V.."? r=} �i i r~i~i.•i fyt~r~r~J 111:* r•r_•r_•r_•r_ •1ti11 1.ti.1.1. 50- r•r.r.r.r 1.1.1.1• -with some dark brown weathered basalt fragments (decomposed basalt). ® ;•r•r•r•r 1.1.1.1. w=27% :-r•r•r•l 1•ti•1•Y r•r•r•r•r Boring completed at 51.5 feet. 60- 70- 80- GeoteCh BORING B-2 (cont.) O UtIons I ncl Norwest-07-0I-gi2 Soil and Rock Description Samples and Data oft— w= moisture content yd= dry unit weight N60= SPT blowcount *= D&M Sampler with 300 pound hammer. Medium stiff, brown SILT; moist. w=36% 10— becomes soft to medium stiff. ® w=32% ya=91 pcf Direct Shear - becomes soft; medium plasticity. w=38°% 20— Medium stiff, orange-brown, SILT with occasional weathered basalt nodules; Fi =25% moist - becomes stiff. w=31% 30— - becomes very stiff and with trace clay. 20 w=28% - becomes stiff. w=32% 40— ® w=32% Boring completed at 41.5 feet. e ch BORING B-3 GSolutions Inc' Norwest-07-0I-gi2 Soil and Rock Description Samples and Data oft— w= moisture content =dry unit weight N,= SPT blowcount *= D&M Sampler with 300 pound hammer. Medium stiff, brown SILT; moist. w=37% 10-- ��Shelby tube sample © w=34% — - becomes soft with trace fine sand. w=40% 20— - becomes medium stiff,gray,and without fine sand; medium plasticity. w=32% - becomes brown with gray mottling; low plasticity. w=33% 30— Very stiff, orange-brown, SILT with gray mottling and occasional weathered m w=23% basalt nodules; moist. Boring completed at 31.5 feet. 40— BORING B-4 G TotieuctilSolutions I ncl Norwest-07-01-gi2 Test Pit# Depth (ft) Soil Description Explorations completed on April 12, 2007 with a John Deere 310E backhoe(Approx. 15,000 lb). TP-I Location: Northeast area of site. Surface conditions: Grass. 0 — 12.0 Medium stiff, brown, SILT with trace organics; moist(4-inch root zone). - grades to without trace organics at 1.5 feet. - becomes stiff at 3.5 feet. - grades to with trace fine sand at 8.0 feet. No seepage observed. No caving observed. TP-2 Location:West-central area of site. Surface conditions: Grass. 0— 1.5 Soft to medium stiff, dark brown, SILT with trace organics; moist(topsoil layer with 4-inch root zone). 1.5 — 12.0 Medium stiff, brown, SILT with occasional organics (roots); moist. - becomes stiff and without occasional organics at 4.0 feet. - grades to with trace fine sand at 8.0 feet. - becomes medium stiff at 10.0 feet. No seepage observed. No caving observed. TP-3 Location: East-central area of site. Surface conditions: Gravel and weeds. 0 —0.3 Medium dense, brown-gray, sandy GRAVEL FILL with trace organics; moist. 0.3— 1.5 Medium stiff, dark brown, SILT with trace organics; moist (buried topsoil layer). 1.5 — 12.0 Medium stiff, brown, SILT with occasional organics (roots); moist. - becomes stiff and without occasional organics at 2.5 feet. - grades to with trace fine sand at 7.0 feet. - with gray mottling at 11.0 feet. No seepage observed. No caving observed. G t c b TEST PIT LOGS solutions I ncl norwest-07-01-gi Test Pit# Depth (ft) Soil Description TP-4 Location: Southeast area of site. Surface conditions: Tall grass, weeds, and blackberry vines. 0— 1.3 Soft to medium stiff, dark brown, SILT with trace organics; moist(8-inch root zone). 1.3 — 12.0 Medium stiff, orange-gray mottled, brown, SILT; moist. - becomes wet at 2.0 feet. - becomes stiff and without mottling at 3.0 feet - grades to with trace fine sand at 7.0 feet. - with dark brown mottling at 9.0 feet. - becomes orange-brown at 1 1.5 feet Slow seepage observed between 2.0 and 3.0 feet. No caving observed. TP-5 Location: Southwest area of site. Surface conditions: Low grass and weeds. 0— 2.5 Soft to medium stiff, dark brown, SILT FILL with trace organics and occasional construction debris (brick fragments); moist(3-inch root zone). - becomes brown at 1.0 feet. - becomes soft and wet at 1.5 feet. 2.5 — 12.0 Medium stiff, orange-gray mottled, brown, SILT; moist. - becomes stiff at 5.0 feet. - grades to with trace fine sand at 7.0 feet. Slow seepage observed between 1.5 and 2.5 feet. Moderate seepage observed below 8.0 feet. Minor caving observed above 2.5 feet. Go}fflch TEST PIT LOGS iu lions Inc! norwest-07-01-gi Test Pit Depth,ft Moisture Content TP-1 0.5 28% TP-1 3.5 30% TP-1 8.0 29% TP-2 1.0 26% TP-2 4.0 34% TP-2 10.0 32% TP-3 1.0 30% TP-3 3.0 33% TP-3 9.0 32% TP-4 1.0 27% TP-4 3.0 35% TP-4 8.0 38% TP-5 1.0 26% TP-5 2.0 35% TP-5 6.0 33% TP-5 11.0 34% GtechMOISTURE CONTENTS Solutions IIlC1 norwest-07-01-gi 4000 f •B-1 @ 15 feet ♦B-2 @ 20 feet 3500 - •B-3 @ 10 feet ---A- 3000 2500 LL d x F- V 2000cc - H c x ' 1500 r 1000 I I r A 500 , I I I I I I I 0 ' 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 NORMAL PRESSURE(PSF) DIRECT SHEAR TEST RESULTS t 6 Solutions I ncl Norwest-07-0I-gi2 www.geodesigninc.com