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Report OFFICE to -y r" RECEIVED SEP 2 3 2021 MIDESIGW. CITY OF TIGARD AN N v 5 COMPANY BUILDING DIVISION SIT2OZJ- 000IB 8i3C) Ofv1ARA Sr REPORT OF GEOTECHNICAL ENGINEERING SERVICES Proposed Tigard Senior Housing 881 5 SW Omara Street Tigard, Oregon For Northwest Housing Alternatives March 30, 2021 Project: NWHA-3-01 / MDESIGNv AN IV15 COMPANY . March 30, 2021 Northwest Housing Alternatives 2316 SE Willard Street Milwaukie, OR 97222 Attention: Josh Carrillo Report of Geotechnical Engineering Services Proposed Tigard Senior Housing 8815 SW Omara Street Tigard, Oregon Project: NWHA-3-01 GeoDesign, Inc., DBA NV5 (GeoDesign) is pleased to submit this report of geotechnical engineering services for the proposed senior housing project located at 881 5 SW Omara Street in Tigard, Oregon. Our services for this project were conducted in accordance with our proposal dated February 5, 2021. We appreciate the opportunity to be of service to you. Please call if you have questions regarding this report. Sincerely, GeoDesign, Inc., DBA NV5 Brett A. Shipton, P.E., G.E. Principal Engineer cc: Rich Poirier, KPFF Consulting Engineers (via email only) GJS:BAS:kt Attachments One copy submitted(via email only) Document ID: NWHA-3-01-033021-geor.docx ©2021 GeoDesign, Inc., DBA NV5 All rights reserved. 9450 SW Commerce Circle,Suite 300 I Wilsonville,OR 97070 1503.968.8787 www.geodesigninc.com TABLE OF CONTENTS PAGE NO. ACRONYMS AND ABBREVIATIONS 1.0 INTRODUCTION 1 2.0 PROJECT UNDERSTANDING 1 3.0 SCOPE OF SERVICES 1 4.0 SITE DESCRIPTION 2 4.1 Surface Conditions 2 4.2 Subsurface Conditions 2 5.0 CONCLUSIONS 3 6.0 SITE DEVELOPMENT RECOMMENDATIONS 4 6.1 Site Preparation 4 6.2 Construction Considerations 5 6.3 Temporary Slopes 5 6.4 Structural Fill 6 6.5 Fill Placement and Compaction 7 6.6 Permanent Cut and Fill Slopes 9 6.7 Excavation 9 6.8 Erosion Control 10 7.0 FOUNDATION SUPPORT RECOMMENDATIONS 10 7.1 Spread Footings 10 7.2 Slabs on Grade 11 8.0 PERMANENT RETAINING STRUCTURES 11 9.0 DRAINAGE CONSIDERATIONS 12 9.1 General 12 9.2 Temporary 12 9.3 Surface 12 9.4 Subsurface 12 9.5 Infiltration Testing 13 10.0 SEISMIC DESIGN CRITERIA 13 11.0 PAVEMENT RECOMMENDATIONS 14 1 1.1 Pavement Design 14 1 1.2 Conventional Pavement Material Requirements 14 12.0 OBSERVATION OF CONSTRUC.I ION 1 5 13.0 LIMITATIONS 15 REFERENCES 1 7 FIGURES Vicinity Map Figure 1 Site Plan Figure 2 CIDESIGN NWHA-3-01:033021 TABLE OF CONTENTS PAGE NO. APPENDIX 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-7 Summary of Laboratory Data Figure A-8 SPT Hammer Calibration WRDESIGtsri AN tl 5 con+t+,cNv NWHA-3-01:033021 ACRONYMS AND ABBREVIATIONS AC asphalt concrete ACP asphalt concrete pavement ASCE American Society of Civil Engineers ASTM American Society for Testing and Materials BGS below ground surface g gravitational acceleration (32.2 feet/second2) H:V horizontal to vertical MCE maximum considered earthquake OSHA Occupational Safety and Health Administration OSSC Oregon Standard Specifications for Construction (2021) pcf pounds per cubic foot pci pounds per cubic inch PG performance grade psf pounds per square foot SOSSC State of Oregon Structural Specialty Code SPT standard penetration test [DESIGN= 011I11PAY NWHA-3-01:033021 1.0 INTRODUCTION GeoDesign, Inc., DBA NV5 (GeoDesign) is pleased to submit this geotechnical engineering report for the proposed senior housing project located at 8815 SW Omara Street in Tigard, Oregon. Figure 1 shows the site relative to existing topographic and physical features. Existing conditions and approximate exploration locations are shown on Figure 2. Acronyms and abbreviations used herein are defined above, immediately following the Table of Contents. 2.0 PROJECT UNDERSTANDING The proposed project includes a new four-story, wood-framed apartment structure located within the existing parking area located east of the existing senior center building. In addition, the existing parking areas surrounding the new building and existing senior center will be redesigned and replaced. Structural loads were not available at the time of this report; however, we have assumed they will be typical for this type of structure. 3.0 SCOPE OF SERVICES The purpose of our services was to provide geotechnical engineering recommendations for use in design and construction of the proposed development. Specifically, we performed the following tasks: • Reviewed readily available, published geologic data and our in-house files for existing information on subsurface conditions in the site vicinity. • Coordinated and managed a field explorations, including locating utilities and scheduling subcontractors and GeoDesign field staff. • Completed a subsurface exploration program at the site consisting of the following: • Four borings within the proposed building footprint to a depth of 31.5 feet BGS • Three borings to a depth of 11.5 feet BGS to perform field infiltration testing • Collected soil samples for laboratory testing and maintained a detailed log of subsurface conditions encountered in the explorations. • Performed a laboratory testing program consisting of the following tests: • Twenty-two moisture content determinations in general accordance with ASTM D2216 • Seven particle-size analyses in general accordance with ASTM D1 140 • Provided recommendations for site preparation and grading, including temporary and permanent slopes, excavations, shoring, fill placement criteria, suitability of on-site soil for fill, subgrade preparation, and wet weather earthwork. • Provided recommendations for design and construction of shallow spread foundations, including allowable capacity, settlement estimates, and lateral response parameters. • Provided recommendations for use in the design of conventional retaining walls, including backfill and drainage requirements and lateral earth pressures. • Provided an evaluation of groundwater conditions at the site and provided general recommendations for dewatering during construction and subsurface drainage. rDSIGNa iw 1 NWHA-3-01:03302 1 - • Provided geotechnical engineering recommendations for design and construction of concrete floor slabs, including an anticipated value for subgrade modulus. • Provided recommendations for construction of AC pavement for on-site access roads and parking areas, including subbase, base course, and AC paving thickness. • Provided recommendations for subsurface drainage of foundations, floor slabs, and pavement. • Provided results of field infiltration testing and general recommendations for on-site stormwater disposal. • Provided a discussion of seismic activity near the site, liquefaction potential, and anticipated deformations. Provided recommendations for seismic design factors as prescribed by the 2019 SOSSC. • Prepared this geotechnical engineering report that presents our findings, conclusions, and recommendations. 4.0 SITE DESCRIPTION 4.1 SURFACE CONDITIONS The site is located on the Tigard Senior Center property in Tigard, Oregon. The property is bordered by residential properties to the west and south, the Tigard Campus of the Northwest Christian Church to the east, and Fanno Creek Park to the north. The new building footprint will be located within the existing parking area east of the existing senior center building. The south portion of the site is relatively flat, and the north portion of the site grades gently downward to the north and east. We have assumed that the new construction will daylight from the existing slope and that cuts and fills for the new construction will be up to approximately 10 feet. 4.2 SUBSURFACE CONDITIONS We explored subsurface conditions at the site by drilling seven borings (B-1 through B-7) to depths between 11.5 and 31.5 feet BGS. The approximate locations of our explorations are shown on Figure 2. A description of our field exploration and laboratory testing programs, the exploration logs, and results of laboratory testing are presented in the Appendix. The borings were drilled within a paved parking lot and encountered pavement sections at the surface consisting of 1 inch to 2 inches of AC over 4 to 12 inches of aggregate base. Our explorations generally encountered undocumented fill over native silt and sand to the maximum depths explored. The following sections summarize each of the subsurface units encountered in the explorations. 4.2.1 Undocumented Fill The AC pavement is underlain by undocumented fill in each of the borings, except B-6, and extends to depths between 4 and 7 feet BGS. The fill consists of loose to medium dense sand and gravel and very soft to very stiff silt containing variable amounts of debris and organics. Laboratory testing indicates that the moisture content of the fill was approximately 16 to 37 percent at the time of our exploration. DESIGN= aro V15cotom.r 2 NWHA 3-01:033021 4.2.2 Sandy Silt The undocumented fill in borings B-1 through B-3 is underlain by sandy silt to a depth of approximately 9.5 feet. SPT results indicate that the sandy silt is very soft to stiff in consistency, and laboratory testing indicates that the moisture content of the sandy silt was approximately 26 to 30 percent at the time of our exploration. 4.2.3 Silty Sand Silty sand is present beneath the sandy silt and undocumented fill and extends to the maximum explored depth in each boring. SPT results indicate that the material is generally very loose to medium dense in consistency. Laboratory testing indicates that the moisture content of the silty sand was approximately 15 to 37 percent at the time of our exploration. Infiltration tests were performed at three locations within the silty sand as discussed in the "Infiltration Testing" section. 4.2.4 Groundwater Groundwater was observed at depths between approximately 7 and 8 feet BGS during infiltration testing in boring B-5, which was drilled using hollow-stem auger methods. Borings B-6 and B-7 were also drilled using hollow-stem auger methods; groundwater was not observed in these borings during drilling. Groundwater was not observed in borings B-1 through B-4 due to mud rotary drilling methods obscuring groundwater levels. Based on our review of nearby water well logs and our experience with sites in the vicinity, groundwater can range between 10 and 15 feet BGS. The depth to groundwater may fluctuate in response to prolonged rainfall, seasonal changes, changes in surface topography, and other factors not observed during this study. 5.0 CONCLUSIONS Based on the results of our study, the site can be developed as proposed. Our geotechnical engineering recommendations for use in design and construction of the proposed development are provided in subsequent sections of this report. The following items will have an impact on design and construction of the proposed development: • The proposed building can be supported on shallow foundations bearing on firm native soil or on structural fill consisting of compacted granular pads bearing on firm native soil, as presented in the "Foundation Support Recommendations" section. • The fine-grained soil at the site is easily disturbed when at a moisture content above optimum. The contractor should be prepared to protect the subgrade during construction. • The on-site fine-grained soil is at a moisture content that is above optimum and will require moisture conditioning if it is to be used as structural fill. • Groundwater is not anticipated to a have an impact on design and construction of the structure. The following sections present general recommendations based on evaluation of results from our geotechnical exploration and analysis and our understanding of the proposed project. [ DESIGNz Pi'T5 3 NWHA-3-01:033021 6.0 SITE DEVELOPMENT RECOMMENDATIONS 6.1 SITE PREPARATION 6.1.1 Demolition Demolition includes removal of the existing structures, floor slabs, foundation elements, pavement, concrete sidewalks, and utilities that may be present underneath areas to be improved. Underground vaults, tanks, manholes, foundation elements, and other subsurface structures should be removed from areas of new foundation elements. Utility lines can be completely removed or grouted full if left in place. Soil disturbed during demolition should be removed and replaced in accordance with the recommendations in the "Structural Fill" section. Material generated during demolition should be transported off site for disposal or stockpiled in areas designated by the owner. In general, this material will not be suitable for re-use as engineered fill. However, AC, concrete, and base rock material may be recycled in accordance with the recommendations provided in the "Structural Fill" section. 6.1.2 Grubbing and Stripping We anticipate minimal stripping and grubbing for the site. Existing landscaped areas should be stripped and removed from all proposed structural fill, pavement, and building areas and for a 5-foot margin around such areas. The actual stripping depth should be based on field observations at the time of construction. Stripped material should be transported off site for disposal or used in landscaped areas. Existing trees or shrubs should be removed from all proposed building areas. In addition, root balls should be grubbed out to the depth of the roots, which could exceed 3 feet BGS. Depending on the methods used to remove the root balls, considerable disturbance and loosening of the subgrade could occur during site grubbing. We recommend that soil disturbed during grubbing operations be removed to expose firm, undisturbed subgrade. The resulting excavations should be backfilled with structural fill. 6.1.3 Undocumented Fill Undocumented fill was observed in our explorations to depths of between 4 and 7 feet BGS. Undocumented fill should be removed from the influence zone of the new building foundation. It should be evaluated during construction where it exists beneath pavement and floor slabs. The exposed subgrade should be closely evaluated by a geotechnical engineer during the construction process. Soil processing, including moisture conditioning and the removal of roots, cobbles, and other deleterious material from the soil, may be required to use the excavated material as structural fill. Compaction should be performed as described in the "Structural Fill" and "Fill Placement and Compaction" sections. 6.1.4 Subgrade Evaluation Upon completion of demolition, stripping, and subgrade preparation, and prior to the placement of fill or new improvements, the exposed subgrade should be evaluated by proof rolling. The subgrade should be proof rolled with a fully loaded dump truck or similarly heavy, rubber tire construction equipment to identify soft, loose, or unsuitable areas. A member of our reSIDESIGM AN V 5 r0A4PAt4 4 NWHA-3-01:033021 geotechnical staff should observe proof rolling to evaluate yielding of the ground surface. During wet weather, subgrade evaluation should be performed by probing with a foundation probe rather than proof rolling. Areas that appear soft or loose should be improved in accordance with subsequent sections of this report. 6.2 CONSTRUCTION CONSIDERATIONS Conventional earthmoving equipment in proper working conditions should generally be capable of making necessary excavations for site cuts and utilities in the fill and native soil. Excavations deeper than 4 feet, or that exhibit caving or raveling, should be shored or laid back at an inclination of at least 1%H:1 V. The fine-grained soil present on this site is easily disturbed. If not carefully executed, site preparation, utility trench work, and excavations can create extensive soft areas and significant repair costs can result. Earthwork planning, regardless of the time of year, should include considerations for minimizing subgrade disturbance. We do not anticipate that the groundwater table will be encountered during construction. However, perched groundwater may be present during the wet season or after periods of precipitation. Consequently, dewatering may be required to control perched groundwater if present. We anticipate that perched groundwater flow, if encountered, will diminish over time and can be addressed using sumps and pumps internal to the excavation. We recommend placing a layer of stabilization material over the subgrade that will be exposed to construction traffic to protect it during wet weather. The contractor has control of the construction schedule and equipment and therefore should be responsible for selecting the appropriate working blanket and thickness. However, it is our opinion that a 12-inch-thick section should be sufficient for light staging areas and an 18-inch-thick section should be sufficient for areas subject to heavy construction traffic. Stabilization material should consist of well-graded gravel, crushed gravel, or crushed rock with a minimum particle size of 3 inches and less than 5 percent by dry weight passing the U.S. Standard No. 4 sieve. Stabilization material should be placed in one lift. Excavations should be made in accordance with applicable OSHA and state regulations. While this report describes certain approaches to excavation and dewatering, the contractor should be responsible for selecting excavation and dewatering methods, monitoring the excavations for safety, and providing shoring as required to protect personnel and adjacent utilities and structures. 6.3 TEMPORARY SLOPES Excavation side slopes less than 10 feet high should be no steeper than 1 Y2H:1 V, provided groundwater is not present. 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 existing upslope 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 the cut supported by shoring. GEODESIGNz -41 T5 MW,arav 5 NWHA-3-01:033021 6.4 STRUCTURAL FILL Structural fill includes fill, slabs, pavement, or any other areas intended to support structures or that are within the influence zones of foundations and structures. Structural fill should be free of organic material and other deleterious materials and, in general, should consist of particles no larger than 3 inches in diameter. Recommendations for suitable fill materials are provided in the following sections. 6.4.1 On-Site Soil The on-site native soil will be suitable for use as structural fill only if it can be moisture conditioned. Based on our experience, the on-site silty soil is sensitive to small changes in moisture content and may be impossible to compact adequately during wet weather or when its moisture content is more than a few percentage points above optimum. 6.4.2 Select Granular Fill Granular material for use as structural fill 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. 6.4.3 Pipe Bedding Utility trench backfill for bedding and in the pipe zone should consist of well-graded granular material with a maximum particle size of 3/ inch and less than 5 percent by dry weight passing the U.S. Standard No. 200 sieve or as required by the pipe manufacturer. 6.4.4 Crushed Rock Crushed rock will be required as base material for floor slabs as specified. Crushed rock fill should consist of imported clean, durable, crushed, angular rock that meets the requirements of the pertinent sections of this report. 6.4.5 Existing AC Pavement,Concrete, and Aggregate Base AC pavement, concrete, and aggregate base from the existing paved areas and improvements can be used in general structural fill, provided particles greater than 6 inches are not present and it is thoroughly mixed with soil so that there are no voids between the fragments. This material should only be used at depths greater than 3 feet below the finished subgrade in general fill areas and at least 3 feet above the pipe zone in trenches. 6.4.6 Geotextile Fabric 6.4.6.1 Separation Geotextile Fabric A separation geotextile fabric can be placed as a barrier to prevent transport of fine-grained landscape soil into the underlying crushed concrete backfill. The subgrade geotextile should meet the requirements in OSSC 02320 (Geosynthetics) for subgrade geotextiles and be installed in conformance with OSSC 00350 (Geosynthetic Installation). i DESIGN% m 5com- 6 NWHA-3-01:033021 6.4.6.2 Drainage Geotextile Fabric Drain rock, and other granular material used for subsurface drains, should be wrapped in a geotextile fabric that meets the specifications provided in OSSC 00350 (Geosynthetic Installation) and OSSC 02320 (Geosynthetics) for drainage geotextiles and be installed in conformance with OSSC 00350 (Geosynthetic Installation). 6.5 FILL PLACEMENT AND COMPACTION Fill soil should be compacted at a moisture content that is near optimum. The maximum allowable moisture content varies with the soil gradation and should be evaluated during construction. Fill and backfill material should be placed in uniform, horizontal lifts and compacted with appropriate equipment. The maximum lift thickness will vary depending on the material and compaction equipment used but should generally not exceed the loose thicknesses provided in Table 1. Fill material should be compacted in accordance with the compaction criteria provided in Table 2. Table 1. Recommended Uncompacted Lift Thickness Recommended Uncompacted Lift Thickness (inches) Compaction Equipment Granular and Crushed Crushed Rock Clayey Soil Rock Maximum Maximum Particle Particle Size S 1Y2 Inches Size > 1Y2 Inches Hand Tools: Plate Compactor and 4 to 8 4 to 8 Not Recommended Jumping Jack Rubber Tire Equipment 6 to 8 10 to 12 6 to 8 Light Roller 8 to 10 10 to 12 8 to 10 Heavy Roller 10 to 12 12 to 18 12 to 16 Hoe Pack Equipment 12 to 16 18 to 24 12 to 16 Table 1 is based on our experience and is intended to serve only as a guideline. The information provided in this table should not be included in the project specifications. `I1'DESIGNi ` ' Y 7 NWHA-3-01:033021 Table 2. Compaction Criteria Compaction Requirements in Structural Zones Percent Maximum Dry Density Determined by ASTM D1557 Fill Type O to 2 Feet > 2 Feet Below Subgrade Below Subgrade Pipe Zone (percent) (percent) (percent) Area Fill 95' 92 Aggregate Base 95 95 Trench Backfill 95' 92 902 Retaining Wall Backfill 95 " 923 1. May be reduced to 92 percent if native soil is used. 2. Or as recommended by the pipe manufacturer. 3. Should be reduced to 90 percent within a horizontal distance of 3 feet from the retaining wall. 6.5.1 Area Fills Imported fill placed to raise site grades should be placed on a prepared subgrade that consists of firm, inorganic site soil or compacted fill. The fill material should be placed in uniform horizontal lifts and compacted to the recommended minimum density provided in Table 2. 6.5.2 Aggregate Bases Aggregate base material under foundations and floor slabs should be placed on a prepared subgrade that consists of firm, inorganic, native soil or compacted fill. Aggregate base material should be placed in uniform horizontal lifts and compacted to the recommended minimum density provided in Table 2. 6.5.3 Trench Backfill Trench backfill in structural areas should consist of select granular fill or crushed rock as described in the "Structural Fill" section and compacted to the minimum density provided in Table 2. Pipe bedding and fill in the pipe zone should be compacted to the minimum density presented in Table 2 or as recommended by the pipe manufacturer. 6.5.4 Retaining Wall Backfill Retaining wall backfill should be compacted to the recommended minimum density provided in Table 2, except that fill within 3 horizontal feet of the wall should be placed in uniform horizontal lifts and compacted to a lesser density of 90 percent of the maximum density, as determined by ASTM D1557, to reduce the effect of compaction-induced stresses against the retaining wall. Settlement of up to 1 percent of the wall height commonly occurs immediately adjacent to retaining walls as the walls rotate and develop lateral active earth pressures. Consequently, we recommend that flatwork(slabs, sidewalks, or pavement) placed adjacent to retaining walls be postponed at least four weeks following wall construction, unless survey data indicates that settlement is complete prior to that time. MIDESIGM AN `Y'5«APA,Y 8 NWHA-3-01:033021 6.6 PERMANENT CUT AND FILL SLOPES Permanent cut and fill slopes in the site soil should be inclined no steeper than 2H:1 V. Upslope buildings, access roads, and pavement should be set back a minimum of 5 feet from the crest of such slopes. 6.7 EXCAVATION 6.7.1 Excavation and Shoring Temporary excavation sidewalls should stand vertical to a depth of approximately 4 feet, provided groundwater seepage is not observed in the sidewalls. Open excavation techniques may be used to excavate trenches with depths between 4 and 8 feet, provided the walls of the excavation are cut at a slope of 1 H:1 V and groundwater seepage is not present. At this inclination, the slopes with loose sand and gravel may ravel and require some ongoing repair. Excavations should be flattened to 1 Y2H:1 V or 2H:1V if excessive sloughing or raveling occurs. In lieu of large and open cuts, approved temporary shoring may be used for excavation support. A wide variety of shoring and dewatering systems are available. Consequently, we recommend that the contractor be responsible for selecting the appropriate shoring and dewatering systems. If box shoring is used, it should be understood that box shoring is a safety feature used to protect workers and does not prevent caving. If excavations are left open for extended periods of time, caving of the sidewalls may occur. The presence of caved material will limit the ability to properly backfill and compact the trenches. The contractor should be prepared to fill voids between the box shoring and the sidewalls of the trenches with sand or gravel before caving occurs. 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. All excavations should be made in accordance with applicable OSHA and state regulations. 6.7.2 Trench Dewatering Dewatering will be required if groundwater is encountered. Pumping from a sump located within the trench may be effective in dewatering localized sections of trench. However, this method is unlikely to prove effective in dewatering long sections of trench or large excavations. In addition, the sidewalls of trench excavations will need to be flattened or shored if seepage is encountered. Where groundwater seepage into shored excavations occurs, we recommend placing at least 1 foot of stabilization material at the base of the excavations. Trench stabilization material should meet the requirements provided in the "Structural Fill" section. We note that these recommendations are for guidance only. Dewatering of excavations is the sole responsibility of the contractor, as the contractor is in the best position to select these systems based on their means and methods. EMIDESIGNY w++ V 5 ""W 9 NWHA-3-01:033021 6.7.3 Safety All excavations should be made in accordance with applicable OSHA requirements and regulations of the state, county, and local jurisdiction. While this report describes certain approaches to excavation and dewatering, the contract documents should specify that the contractor is responsible for selecting excavation and dewatering methods, monitoring the excavations for safety, and providing shoring (as required) to protect personnel and adjacent structural elements. 6.8 EROSION CONTROL The on-site soil is moderately susceptible to erosion. Consequently, we recommend that slopes be covered with an appropriate erosion control product if construction occurs during periods of wet weather. We recommend that 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 as straw bales, sediment fences, and temporary detention and settling basins should be used in accordance with local and state ordinances. 7.0 FOUNDATION SUPPORT RECOMMENDATIONS The proposed structure can be supported on conventional spread footings bearing on firm, undisturbed native soil or on structural fill underlain by firm, undisturbed native soil. Foundations should not be established on undocumented fill, soft soil, or soil containing deleterious material. If present, this material should be removed and replaced with structural fill. 7.1 SPREAD FOOTINGS 7.1.1 Bearing Capacity mmend that s-pr footings be sized based on an allowable bearing pressure of 2,500 psf for footings firm native soil or on crushed rock overlying firm native soil. This is a earinq o ; 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 50 percent for short-term loads, such as those resulting from wind or seismic forces. The planned structure can be supported by isolated column and continuous wall footings. We recommend that isolated column and continuous wall footings have minimum widths of 24 and 18 inches, respectively. The bottom of exterior footings and wall footings should be founded at least 18 inches below the lowest adjacent grade. Interior column footings should be founded at least 12 inches below the base of the adjacent floor slab. 7.1.2 Lateral Resistance Lateral loads can be resisted by passive earth pressure on the sides of footings and by friction on the base of footings. We recommend a friction coefficient of 0.30 for footings that bear on native soil and 0.40 for computing the friction capacity of building foundations that bear on granular pads. An equivalent fluid unit weight of 350 pcf is recommended to compute passive earth pressure acting on footings constructed in direct contact with compacted structural fill or native soil. This value is based on the assumptions that the adjacent confining structural fill or [ DESIGN ANN 5 P`"" 10 NWHA-3-01:033021 native soil is level and that groundwater remains below the base of the footing. The top 1 foot of soil should be neglected when calculating lateral earth pressures unless the foundation area is covered with pavement or is inside a building. 7.1.3 Settlement Post-construction settlement of footings is expected to be less than 1 inch. Differential settlement between similarly loaded foundations should be approximately one-half of the total settlement. 7.2 SLABS ON GRADE Satisfactory subgrade support for building floor slabs supporting floor loads of up to 100 psf can be obtained, provided the subgrade is prepared in accordance with the "Site Preparation" section. A minimum 6-inch-thick layer of crushed rock(imported granular material) should be placed and compacted over the prepared subgrade to provide a firm surface and to assist as a capillary break. The imported granular material should be crushed rock or crushed gravel and sand meeting the requirements outlined in the "Structural Fill" section. 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 by ASTM D1557. Floor slab base rock contaminated with excessive fines (greater than 5 percent by dry weight passing the U.S. Standard No. 200 sieve) should be replaced. A subgrade modulus of 100 pci may be used to design floor slabs constructed on subgrade prepared as recommended in the "Site Preparation" section. Settlement of floor slabs supporting the anticipated design loads and constructed as recommended is not expected to exceed approximately%2 inch. 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. 8.0 PERMANENT RETAINING STRUCTURES Permanent retaining structures free to rotate slightly around the base should be designed for active earth pressures using an equivalent fluid unit pressure of 35 pcf. If retaining walls are restrained against rotation during backfilling, they should be designed for an at-rest earth pressure of 55 pcf. This value is based on the assumptions that (1) the retained soil is level, (2) the backfill consists of granular material, (3) the backfill is drained, and (4) the wall is less [DESIGN= AN iV15MMr 1 1 NWHA 3-01:033021 than 10 feet in height. Seismic lateral forces can be calculated using a dynamic force equal to 6.5H2 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 for shallow foundations. Drains consisting of a perforated drainpipe wrapped in a geotextile filter should be installed behind exterior walls. The pipe should be embedded in a zone of coarse sand or gravel containing less than 2 percent by dry weight passing the U.S. Standard No. 200 sieve and should outlet to a suitable discharge. 9.0 DRAINAGE CONSIDERATIONS 9.1 GENERAL We recommend that 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 that the ground surface adjacent to the buildings be sloped to facilitate positive drainage away from the building. 9.2 TEMPORARY During grading at the site, the contractor should be made responsible for temporary drainage of surface water as necessary to prevent standing water and/or erosion at the working surface. During rough and finished grading of the building site, the contractor should keep all footing excavations and building pads free of water. 9.3 SURFACE The finished ground surface around the building should be sloped away from the foundations at a minimum 2 percent gradient for a distance of at least 5 feet. Downspouts or roof scuppers should discharge into a storm drain system that that carries the collected water to an appropriate stormwater system. Trapped planter areas should not be created adjacent to the building without providing means for positive drainage (i.e., swales or catch basins). 9.4 SUBSURFACE Assuming the site grades around the building will be sloped as discussed previously, it is our opinion that perimeter footing drains will not be required around the proposed building. However, the use of these drains should be considered in areas where landscaping planters are placed approximate to the foundations or where surface grades cannot be completed as outlined above. If installed, footing drains should consist of a filter-fabric wrapped, drain-rock filled trench that extends at least 12 inches below the lowest adjacent grade (i.e., slab subgrade elevation). A perforated pipe should be placed at the base to collect water that gathers in the drain rock. The drain rock and filter fabric should meet specifications outlined in the"Structural Fill" section. Discharge for the footing drain should not be tied directly into the stormwater drainage system, unless mechanisms are installed to prevent backflow. I „ DESIGN V[503 4 12 NWHA-3-01:033021 9.5 INFILTRATION TESTING Infiltration testing was completed to assist in the evaluation of infiltration rates at the site. Testing was performed at a depth of 10 feet BGS in borings B-5 through B-7 using the encased falling head test method. After soaking the soil under a constant head of water, infiltration rates were measured under low-head conditions of approximately 1 foot to 2 feet of water. Fines content testing was conducted on representative soil samples collected at the depths of the infiltration tests. Results of the fines content testing are presented in the Appendix. Table 3 summarizes the results of infiltration testing and fines content analysis. Table 3. Field Measured Infiltration Rate Depth Soil Type Measured Fines Location Infiltration Rate' Content2 (feet BGS) at Test Depth (inches per hour) (percent) B-5 10 Silty Sand —0 49 B-6 10 Silty Sand —0 50 B-7 10 Silty Sand 3.4 28 1. Infiltration rates are not factored. 2. Fines content: material passing the U.S.Standard No. 200 sieve The infiltration rates presented in Table 3 are unfactored. Correction factors should be applied to the measured infiltration rate to account for soil variations and the potential for long-term clogging due to siltation and buildup of organic material. We recommend a minimum factor of safety of at least 2 be applied to the field infiltration values presented above. 10.0 SEISMIC DESIGN CRITERIA The subsurface soil is moderately susceptible to liquefaction. We estimate approximately 2 inches of liquefaction-induced settlement under design levels of ground shaking. A differential settlement of 1 inch should be assumed over a distance of 50 feet. Because the area is likely susceptible to liquefaction, the site would be classified as Site Class F in accordance with the 2019 SOSSC. However, if the proposed building has a fundamental period of less than 0.5 second, a soil profile consistent with Site Class E can be used to compute base shear forces. Table 4 presents the seismic coefficients prescribed by the 2019 SOSSC for Site Class E. C DESIGN'i `V 5con+v'4Y 13 NWHA-3-01:033021 Table 4. 2019 SOSSC Seismic Design Parameters Seismic Design Parameter Short Period 1 Second Period MCE Spectral Acceleration S, = 0.857 g S1 = 0.394 g Site Class F1 Site Coefficient Fa= 1.3 F,= 2.4 Adjusted Spectral Acceleration S,S= 1.115 g SM, = 0.946 g Design Spectral Response Acceleration Parameters = 0.743 g Sol = 0.630 g 1. Site Class E can be used to compute base shear if the fundamental period of the building is less than 0.5 second. Per ASCE 7-16 Section 11.4.8, a site response analysis is required for this project unless the structural engineer determines that Exception 2 in the code applies, which requires calculating the building's seismic response coefficient. If a site response analysis is needed, we will perform this additional analysis. If a site response analysis is not needed, the seismic design parameters presented in Table 4 from ASCE 7-16 may be used for design. We obtained these parameters from the ASCE 7 hazard tool (ASCE, 2018). 11.0 PAVEMENT RECOMMENDATIONS 11.1 PAVEMENT DESIGN The pavement subgrade should be prepared in accordance with the previously described recommendations in the "Site Preparation,""Construction Considerations," and "Structural Fill" sections. Our pavement recommendations are based on a minimum California bearing ratio value of 3 and a design life of 20 years. We do not have specific information on the frequency and type of vehicles that will use the area; however, we have assumed that post-construction traffic conditions will consist of no more than five heavy trucks per day. We recommend a pavement section consisting of a minimum of 3.0 inches of AC pavement underlain by a minimum of 10.0 inches of crushed base rock. For areas subject to passenger car traffic only, we recommend a pavement section consisting of a minimum of 2.5 inches of AC pavement underlain by a minimum of 10.0 inches of crushed base rock. All thicknesses are intended to be the minimum acceptable. Design of the recommended pavement sections assume that construction will be completed during an extended period of dry weather. Wet weather construction could require an increased thickness of aggregate base. 11.2 CONVENTIONAL PAVEMENT MATERIAL REQUIREMENTS The AC should be Level 2, %Z-inch, dense ACP as described in OSSC 00744(Asphalt Concrete Pavement) and compacted to 91 percent of the specific gravity of the mix, as determined by ASTM D2041. Minimum lift thickness for Y2-inch, dense ACP is 2.0 inches. Asphalt binder should be performance graded and conform to PG 64-28. [1RDESIcNY aw V15coMRMdr 14 NWHA3-01:033021 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 Northwest Housing Alternatives and their consultants for this specific project. 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. 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 this 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. ♦ ♦ ♦ [NADESSIGNz V15CfjManNr 15 NWHA-3-01:033021 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., DBA NV5 � Ep PR O,cFS 4,� 1 NE6" �'/0 Gregory). Schaertl, P.E. •Lis9 r Associate Engineer v. t�� �Y1 A ME.S SC' Brett A. Shipton, P.E., G.E. EXPIRES: 06/30/22 Principal Engineer Cif"'•DESIGNS N'V 5N 16 NWHA-3-01:033021 W4tkiHSYYxNkMH WrN.lixrsud xuvauusNufltukuvYaW.18:.azsNerxiei;; REFERENCES ASCE, 2016. Minimum Design Loads for Buildings and Other Structures, ASCE/SEI 7-016. ASCE, 2018. ASCE 7 Hazard Tool. Obtained from website: https://asce7hazardtool.online/. 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IR t �s � a * ; t� *g ���t af .�Lh ,.;g�1 " �1P `"�s �+ .:.u�..', �� ., fi n,,._ sed,.a.�• '. � :� ..- NWHA-3-01 G EODESIGN? SITE PLAN AN NIYIS COMPANY PROPOSED TIGARD SENIOR HOUSING '' ' MARCH 2021 FIGURE 2 TIGARD,OR APPENDIX APPENDIX FIELD EXPLORATIONS GENERAL We explored subsurface conditions at the site by drilling seven borings (B-1 through B-7) to depths of between 11.5 and 31.5 feet BGS at the approximate locations shown on Figure 2. Drilling services were provided by Western States Soil Conservation, Inc. of Hubbard, Oregon, using a truck-mounted drill rig on February 25 and 26, 2021. A member of our geology staff observed the explorations. The exploration logs are presented in this appendix. The locations of the explorations were determined in the field by pacing from existing site features. This information should be considered accurate to the degree implied by the methods used. SOIL SAMPLING We collected representative samples of the various soils encountered in the explorations for geotechnical laboratory testing. Samples were collected from the borings using a 1 Y2-inch-inside diameter, split-spoon sampler(SPT sampler). The split-spoon sampling was conducted in general accordance with ASTM D1586. The 1%z-inch-inside diameter, split-spoon samplers were driven into the soil with 140-pound hammer free falling 30 inches. The samplers were driven a total distance of 18 inches. The number of blows required to drive the sampler the final 12 inches is recorded on the exploration logs, unless otherwise noted. 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 87.4 percent. The calibration testing results are presented at the end of this appendix. SOIL CLASSIFICATION The soil samples were classified in the field 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 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 shown on the exploration logs if those classifications differed from the field classifications. "IDESIGN m 'V 5°`'M#M°r A-1 NWHA 3-01:033021 MOISTURE CONTENT The natural moisture content of selected soil samples was determined in general accordance with ASTM D2216. The natural moisture content is a ratio of the weight of the water to dry soil in a test sample and is expressed as a percentage. 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 is a quantitative determination of the amount of material finer than the U.S. Standard No. 200 sieve expressed as a percentage of soil weight. The test results are presented in this appendix. [DESIGM ri N`#k5 PANw A-2 NWHA 3-01:033021 SYMBOL SAMPLING DESCRIPTION E Location of sample collected in general accordance with ASTM D1586 using Standard Penetration Test with recovery Location of sample collected using thin-wall Shelby tube or Geoprobe® sampler in general accordance with ASTM D1 587 with recovery Location of sample collected using Dames & Moore sampler and 300-pound hammer or pushed with recovery Location of sample collected using Dames & Moore sampler and 140-pound hammer or pushed with recovery 1 Location of sample collected using 3-inch-O.D. California split-spoon sampler and 140-pound hammer with recovery NLocation of grab sample Graphic Log of Soil and Rock Types •i'. Observed contact between soil or ] Rock coring interval - ` rock units (at depth indicated) EZ Water level during drilling Inferred contact between soil or rock units(at approximate depths indicated) Water level taken on date shown :`: — - ,t, ._'p y• GEOTECHNICAL TESTING EXPLANATIONS ATT Atterberg Limits P Pushed Sample I 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 Non-Plastic 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 - `"DESIGN? EXPLORATION KEY TABLE A-1 AN N 1 5 COMPANY 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 1 1 - 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 Unconfined Consistency Penetration Sampler Sampler Compressive Strength Resistance (140-pound hammer) (300-pound hammer) (tsf) 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) GRAVEL WITH FINES GW-GM or GP-GM GRAVEL with silt (more than 50%of (> 5%and <_ 12%fines) GW-GC or GP-GC GRAVEL with clay coarse fraction retained on GM silty GRAVEL COARSE- No. 4 sieve) GRAVEL WITH FINES GC clayey GRAVEL GRAINED SOIL (> 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) SW-SC or SP-SC SAND with clay coarse fraction 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 ,,i , , !_, > 30 sandy/gravelly Indicate% WilDESIGIT4 SOIL CLASSIFICATION SYSTEM TABLE A-2 AN N V 5 COMPANY u Z = 0 w ♦BLOW COUNT INSTALLATION AND DEPTH = MATERIAL DESCRIPTION Q w ►_ °' •MOISTURE CONTENT% COMMENTS FEET o- W o IL/ MT1 RQD% P7a CORE REC% t- 0 q.. 0 5o loo :� ASPHALT CONCRETE(2.0 inches). I 0.2 -° BASE(1 2.0 inches). \AGGREGATE /' 1.2 - 10 Medium dense, dark gray, silty GRAVEL with sand (GM), trace organics; moist �o•:� 1 11 FILL. ♦ • Stiff, dark gray SILT with sand (ML), 3.8 — 5— trace organics; moist, sand is fine - FILL. PP !ri AZ • PP=2.0tsf medium stiff, sandy, with gravel at 5.0 feet J_ 7.0 Soft to medium stiff, gray with brown- 4 orange mottled, sandy SILT(ML); moist, P200 111 A • P200=56% sand is fine. • 10— . '—i Medium dense, gray with brown-orange 9.5 mottled, silty SAND (SM); moist, sand is I] 4114 fine. 15 ; ;- loose, brown with orange mottles, trace gravel; wet, sand is fine to medium, rapid dilatancy at 1 5.0 feet 20 25 ``• medium dense at 25.0 feet 1E cn ui 3o brown with orange and black mottles at11 `s • - ` 30.0 feet a Exploration completed at a depth of 31.5 Surface elevation was not measured at the time of 31.5 feet. exploration. Hammer efficiency factor is 87.4 3s— percent. 0 z z u a 40 ce 0 50 100 a DRILLED BY:Western States Soil Conservation,Inc. LOGGED BY:H.Herincta COMPLETED:02/25/21 z BORING METHOD:mud rotary(see document text) BORING BIT DIAMETER:3 7/8 inches ° GEODESIGNz NWHA-3-01 BORING B-1 AN N v {V I M r(�COMPANY MARCH 2021 PROPOSED TIGARD SENIOR HOUSING TIGARD, OR FIGURE A-1 .. • 2 O= u w A BLOW COUNT INSTALLATION AND t-I— z COMMENTS DEPTH Q a a •MOISTURE CONTENT MATERIAL DESCRIPTION >w I— FEET 0- w 0 w < RQD% 1771 CORE REC% Lc/ "'� I— 0 50 100 0 77 ASPHALT CONCRETE(2.0 inches). /J 0.2 ,o \AGGREGATE BASE(12.0 inches). r 1 2 © N Medium dense, brown with orange ,r�� mottled, silty GRAVEL with sand (GM), 13 10 trace organics; moist, gravel is fine to40 coarse and subrounded to subangular s_ •� '1�- FILL 4.5 Very soft, dark brown with orange mottled, sandy SILT(ML), trace organics; moist, sand is fine to coarse. medium stiff to stiff, gray-brown with orange mottles; sand is fine at 7.5 feet P200 P200=50% )o—.Si Loose to medium dense, brown-orange, 9'5 • : }, silty SAND (SM); moist, sand is fine. 111 io 15 • •tih. medium dense, brown with orange and 11 12 • black mottles; wet, rapid dilatancy at 15.0 feet 20 :r 1 ;... loose, brown with orange mottles at 11 20.0 feet 25 medium dense at 25.0 feet F i3 _ • N Itl a 4:'' • 30 loose to medium dense, brown; moist io -• at 30.0 feet o - Exploration completed at a depth of 31.5 Surface elevation was not u measured at the time of 31.5 feet. exploration. Hammer efficiency factor is 87.4 ss— percent. 0 z z w a 40 0 50 100 w a DRILLED BY:Western States Soil Conservation,Inc. LOGGED BY:H.Herinclot COMPLETED:02/26/21 Lri o BORING METHOD:mud rotary(see document text) BORING BIT DIAMETER:3 7/8 inches o• LI i DESIGN= NWHA 3 01 BORING B-2 o /�I COMPANY PROPOSED TIGARD SENIOR HOUSING AN Ni i f MARCH 2021 TIGARD,OR FIGURE A-2 + u Z 9 0= u w A BLOW COUNT INSTALLATION AND DEPTH v_ Q a Z a •MOISTURE CONTENT% COMMENTS FEET a MATERIAL DESCRIPTION >"' w N RQD% CORE REC% Q w0 U W ~ 0 50 100 0— nd� ASPHALT CONCRETE(1.0 inch). 07 \AGGREGATE BASE(8.0 inches). / 0.8 Medium stiff to stiff, dark gray with brown mottled SILT with gravel and 8 sand (ML), trace organics; moist - FILL. A • s medium stiff, sandy, trace gravel at 5.0 ` - feet _ Medium stiff, dark gray with brown 7.0 s - mottled, sandy SILT with gravel (ML), i A. • some organics; moist, sand is fine, _ --.• -1 gravel is fine and subangular. 10 ry''"" Ve loose, J_ e.s gray-green with brown , '' orange mottled, silty SAND (SM); moist, P200 Ii A • P200=48% sand is fine. 1 s—, .- medium dense, brown with orange- !il1 =:,' black mottles at 1 5.0 feet 20— brown with orange mottles; sand is fine 11] 1 --:,,•:,-; to medium, rapid dilatancy at 20.0 feet 25 brown at 25.0 feet 20 C rn N _vY I- O so— ~:� brown with orange and black mottles; 11 `s - -.• moist to wet at 30.0 feet 0 Exploration completed at a depth of 31.5 Surface elevation was not t? measured at the time of > 31.5 feet. exploration. z o -- Hammer efficiency factor is 87.4 E 3s— percent. K. 3 z u, - u a 40 w 0 50 100 a DRILLED BY:Western States Soil Conservation,Inc. LOGGED BY:H.Herincla COMPLETED:02/25/21 > z p BORING METHOD:mud rotary(see document text) BORING BIT DIAMETER:37/8inches u us DESIGN= NWHA-3-01 BORING B-3 Z Ye An NIV 5 COMPANY MARCH 2021 PROPOSED TIGARD SENIOR HOUSING FIGURE A-3 TIGARD, OR z . O O z t.7 w ♦BLOW COUNT INSTALLATION AND DEPTH P 1— z —I COMMENTS Q 0- a •MOISTURE CONTENT% MATERIAL DESCRIPTION >w I- 2 FEET ° w o If; < flTfl RQD% V CORE REC% u "t I- 0 50 100 0 7-77;71ASPHALT CONCRETE(1.0 inch). 01 \AGGREGATE BASE(4.0 inches). / 0.4 Very stiff, dark gray with green mottled, sandy SILT with gravel and r 17 • debris (wood)(ML), trace organics; h. moist, sand is fine to coarse, gravel is — 5— fine - FILL. r. very soft to soft, dark gray-brown, 2 without gravel and debris at 5.0 feet — Medium dense, green-gray with orange 70 . - - mottled, silty SAND (SM); moist, sand is P200II r2 • P200=41% • fine. °�.•'"`= loose to medium dense, brown with C io •' ` *: orange, gray, and green mottles; moist to wet, rapid dilatancy at 10.0 feet 5 :._'., medium dense, brown with orange 11 40 • mottles; wet at 1 5.0 feet 20�,:` brown; moist to wet, sand is fine to 16 - medium at 20.0 feet II 4' 25-�' 15 Y a.k Ill N s T N W ao - s' • 30—o. it's; gray with black streaks at 30.0 feet 11 4\ 3 ' i- 31.5 Surface elevation was not o Exploration completed at a depth of u measured at the time of u+ 31.5 feet. exploration. z s - Hammer efficiency factor is 87.4 percent. u 35— 0 iI ri, Q I u, U a 40 0 50 100 w a DRILLED BY:Western States Soil Conservation,Inc. LOGGED BY:H.Herinclot COMPLETED.02/26/21 > z o BORING METHOD:mud rotary(see document text) BORING BIT DIAMETER:3 7/8 inches u o i DESIGN_ NWHA-3-01 BORING B-4 Z Cja�•��(('j PROPOSED TIGARD SENIOR HOUSING NI 1� '9Y MARCH 2021 TIGARD,OR FIGURE A-4 u Z ° O= U UJ A BLOW COUNT INSTALLATION AND DEPTH = Q a Z n. •MOISTURE CONTENT% COMMENTS FEET a MATERIAL DESCRIPTION w 0 w Q RQD% I771 CORE REC% w I- '^ 0 50 100 ° 7 , ASPHALT CONCRETE(1.0 inch). r 0.1 \AGGREGATE BASE(4.0 inches). 0.4 - Very soft to soft, dark gray with green mottled, sandy SILT(ML), trace F 2 organics; moist- FILL. A • 5 dark brown, with debris (wood), trace gravel at 5.0 feet PP • PP=1.0 tsf Very loose to loose, green-gray with 70 - dark green mottled, silty SAND(SM); moist, sand is fine. 10 Y^;; loose, gray; sand is fine to medium, Infiltration test at 10.0 feet. • rapid dilatancy at 10.0 feet P200 P200=49% Exploration completed at a depth of 11.5 Surface elevation was not 1 1.5 feet. measured at the time of exploration. Hammer efficiency factor is 87.4 percent. 15- 20— 25— Y M - W i- z 30 — d z 0 35 (n 0 - Q S _ Z w - U d 40 0 50 100 w a- DRILLED BY:Western States Soil Conservation,Inc. LOGGED BY:H.Herinckx COMPLETED:02/26/21 z BORING METHOD:hollow-stem auger(see document text) BORING BIT DIAMETER:41/4 inches u CDESIGNZ NWHA-3-01 BORING B-5 m AN Ni lCOMPANY MARCH 2021 PROPOSED TIGARD SENIOR HOUSING TIGARD,OR FIGURE A 5 ZI 0 O 2 U w ♦BLOW COUNT INSTALLATION AND t•- z w COMMENTS DEPTH Q a _ °- •MOISTURE CONTENT FEET = MATERIAL DESCRIPTION w 0 I— 2 w < FITT1 RQD% 1771 CORE REC% Ln v w ~ 0 50 100 0 70 ASPHALT CONCRETE(2.0 inches). [ 0.2 P- AGGREGATE BASE(1 2.0 inches). r 1.2 Loose, brown, silty SAND (SM), trace organics; moist, sand is fine. r• 5 • medium dense at 5.0 feet =4 loose, brown with dark brown streaks at 7.5 feet 4 Infiltration test at 10.0 feet. P200 111 A • P200=50% Exploration completed at a depth of 17.5 Surface elevation was not 1 1.5 feet. measured at the time of exploration. Hammer efficiency factor is 87.4 percent. 15- 20- 25— I- Y - N ltl a z 30—0_ rl a 0 v z 0 u - u 35— N- m - 0 rn 2 z Z U • 40 0 50 100 a DRILLED BY:Western States Soil Conservation,Inc. LOGGED BY'.H.Herincla COMPLETED.02/26/21 z Z BORING METHOD:hollow-stem auger(see document text) BORING BIT DIAMETER:4114inches • MIDESIGNZ NWHA-3-01 BORING B-6 �JP MARCH 2021 FIGURE A-6 PROPOSED TIGARD SENIOR HOUSING ANNIV TIGARD, OR ......._... .., .. .. ..,...,.. ..................�......,..... .....,.. •.., . µ .. xaxr xrtatesat s•exuxr. xuasrtatwaaatMutsllMiLLliM� ttc.raa.x al.xtteu a...xarsH• ruar.esa. +.u«sta «i..s«... z ° O= u w ♦BLOW COUNT INSTALLATION AND J COMMENTS DEPTH -' MATERIAL DESCRIPTION Q w 1— a •MOISTURE CONTENT FEET w 0 w < ITTTI RQD% 1771 CORE REC% WI _ 0 50 100 —0 °-'77\ASPHALT CONCRETE(1.0 inch). 0.1 :;• ,AGGREGATE BASE(4.0 inches). 0.4 Loose, brown, silty SAND with debris '•: (asphalt concrete) (SM), trace gravel and organics; moist, sand is fine - FILL. 111 A • Loose, brown, silty SAND (SM); moist, 4.0 5 :'' sand is fine, lenses of brown with orange mottled, sandy SILT. A lJ A medium dense; sand is fine to medium — 13 Infiltration test at 10.0 feet. '� at 10.0 feet P200 A P200=28% Ex loration com leted at a de th of 5 p P p Surface elevation was not 1 1.5 feet, measured at the time of exploration. Hammer efficiency factor is 87.4 1s— percent. 20— 25— Y _ N n1 Q _ ❑ 30— Lri H ❑ U z Z U - u 35— m 0 I � — z 40 0 50 100 d DRILLED BY:Western States Soil Conservation,Inc. LOGGED BY'.H.Herincla COMPLETED.02/25/21 z BORING METHOD hollow-stem auger(see document text) BORING BIT DIAMETER:4 1/4 inches 1DESIGN? NWHA-3-01 BORING B-7 PROPOSED TIGARD SENIOR HOUSING nN N (5 COMPANY MARCH 2021 FIGURE A-7 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 2.5 20 B-1 5.0 23 B-1 7.5 27 56 B-1 15.0 29 B-1 30.0 31 B-2 2.5 16 B-2 7.5 30 50 B-2 15.0 37 B-3 2.5 25 B-3 7.5 26 B-3 10.0 28 48 B-3 15.0 32 B-4 2.5 32 B-4 7.5 31 41 B-4 15.0 32 B-5 2.5 24 B-5 5.0 37 B-5 10.0 33 49 z B-6 2.5 15 n m B-6 10.0 28 50 w B-7 2.5 20 a B-7 10.0 31 28 u z 0 u Lit 0 > 0 [ DESIGN= NWHA-3-01 SUMMARY OF LABORATORY DATA AN NIVIu COMPANY MARCH 2O21 PROPOSED TIGARD SENIOR HOUSING TIGARD, OR FIGURE A-8 3 Pile Dynamics, Inc. RIG#9 SPT Analyzer Results PDA-S Ver.2018.30-Printed:4/15/2020 Summary of SPT Test Results Project:WSSC-8-05,Test Date:4/13/2020 EMX: Maximum Energy ETR: Energy Transfer Ratio-Rated Start Final N N60 Average Average Depth Depth Value Value EMX ETR ft ft ft-lb % 42.50 44.00 18 26 306.23 87.5 45.00 46.50 17 24 304.53 87.0 50.00 51.50 12 17 305.90 87.4 52.50 54.00 26 37 306.91 87.7 Overall Average Values: 306.02 87.4 Standard Deviation: 4.49 1.3 Overall Maximum Value: 313.51 89.6 I Overall Minimum Value: 294.12 84.0 11 www.geodesigninc.com