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Studies Applicant 4/5/2024
14835 SW 72nd Avenue Tel (503) 598-8445 Portland, Oregon 97224 Fax (503) 941-9281 Real-World Geotechnical Solutions Investigation • Design • Construction Support Preliminary Geotechnical Engineering Report Project Information: Woodland Ridge Phases 3 through 8 GeoPacific Project No. 21-5865 December 27, 2021 Site Location: Mt. Vernon Rd & Jasper Rd Springfield, Oregon 97478 Lane County Property No. 1802040002800 Client: Mr. Scott Morris, P.E. A&O Engineering, LLC 380 Q Street, Ste. 200 Springfield, Oregon 97477 Phone: (541) 302-9790 Email: scottmorris@ao-engr.com 21-5865, Woodland Ridge Phases 3-8 Geotechnical Report Version 1.0, December 27, 2021 TABLE OF CONTENTS 1.0 PROJECT INFORMATION ..................................................................................................................... 1 2.0 SITE AND PROJECT DESCRIPTION .................................................................................................... 1 3.0 REGIONAL GEOLOGIC SETTING AND LANDSLIDE MAPPING ......................................................... 2 4.0 REGIONAL SEISMIC SETTING ............................................................................................................. 2 4.1 Cascadia Subduction Zone ................................................................................................................. 2 5.0 FIELD EXPLORATION AND SUBSURFACE CONDITIONS ................................................................. 2 5.1 Soil Descriptions ................................................................................................................................. 3 5.2 Shrink-Swell Potential ......................................................................................................................... 4 5.3 Groundwater and Soil Moisture .......................................................................................................... 5 5.4 Infiltration Testing................................................................................................................................ 5 6.0 LANDSLIDE HAZARD AND SLOPE STABILITY STUDY ...................................................................... 6 6.1 Literature Review ................................................................................................................................ 6 6.2 LiDAR Review ..................................................................................................................................... 8 6.3 Field Reconnaissance Subsurface Exploration .................................................................................. 8 6.4 Quantitative Slope Stability Modeling ................................................................................................. 9 6.4.1 Existing Conditions Analysis ........................................................................................................... 9 6.4.2 Post-Construction Analysis ........................................................................................................... 10 6.5 Slope Stability Analysis Summary .................................................................................................... 12 7.0 CONCLUSIONS AND RECOMMENDATIONS .................................................................................... 12 7.1 Site Preparation Recommendations ................................................................................................. 13 7.2 Keyways, Benching, and Subdrains for Fill Slopes .......................................................................... 14 7.3 Engineered Fill .................................................................................................................................. 15 7.4 Cement Amending Procedures ......................................................................................................... 16 7.5 Excavating Conditions and Utility Trench Backfill ............................................................................. 17 7.6 Erosion Control Considerations ........................................................................................................ 18 7.7 Wet Weather Earthwork .................................................................................................................... 18 7.8 Spread Foundations ......................................................................................................................... 19 7.9 Concrete Slabs-on-Grade ................................................................................................................. 20 7.10 Footing and Roof Drains ................................................................................................................... 20 7.11 Permanent Below-Grade Walls ........................................................................................................ 21 8.0 SEISMIC DESIGN ................................................................................................................................ 23 8.1 Soil Liquefaction................................................................................................................................ 23 9.0 UNCERTAINTIES AND LIMITATIONS ................................................................................................ 24 REFERENCES ................................................................................................................................................. 25 CHECKLIST OF RECOMMENDED GEOTECHNICAL TESTING AND OBSERVATION ............................... 26 APPENDIX 21-5865, Woodland Ridge Phases 3-8 Geotechnical Report i Version 1.0, December 27, 2021 List of Appendices Figures Exploration Logs Laboratory Test Results Slope Stability Cross-Sections Site Research Photographic Log List of Figures 1 Site Vicinity Map 2 3A 3B 3C Site Aerial and Exploration Locations Site Plan and Exploration Locations Site Plan and Exploration Locations Site Plan and Exploration Locations 4 5 6 LiDAR Imagery & Landslide Inventory Typical Perimeter Footing Drain Detail Fill Slope Detail Preliminary Geotechnical Engineering Report Project No. 21-5865, Woodland Ridge Phases 3-8, Springfield, Oregon 21-5865, Woodland Ridge Phases 3-8 Geotechnical Report 1 Version 1.0, December 27, 2021 1.0 PROJECT INFORMATION This report presents the preliminary results of a geotechnical engineering study conducted by GeoPacific Engineering, Inc. (GeoPacific) for the above-referenced project. The purpose of our investigation was to evaluate subsurface conditions at the site, assess potential geologic hazards at the property, and to provide geotechnical recommendations for site development. This geotechnical study was performed in accordance with GeoPacific Proposal No. P-7818, dated July 22, 2021, and your subsequent authorization of our proposal and General Conditions for Geotechnical Services. 2.0 SITE AND PROJECT DESCRIPTION As indicated on Figures 1 and 2, The subject site is located northeast of the intersection of Mt. Vernon Road, and Jasper Road, in Springfield, Oregon. The site consists of Lane County Property No. 1802040002800 on tax map 18020400 Springfield, totaling approximately 72.87-acres in size. The site latitude and longitude are 44.036889, -122.938837. The regulatory jurisdictional agency is the City of Springfield, Oregon. The site is bordered by Phases 1 and 2 of the Woodland Ridge residential subdivision to the north, by existing residential homes to the east, and west, and by railroad tracks, Mt. Vernon Road, and Jasper Road to the south. Historically the majority of the property has been largely undeveloped or utilized as agricultural land. A residential home and detached out -building were present in the northeastern corner of the property but it was recently demolished. Gravel and dirt drive lanes are present in the southern, eastern, and northeastern portions of the site. We understand that there may be underground utilities that cross the site. Currently vegetation a t the property consists primarily of an open grassy field. Trees are present along the northern margin of the site. Topography at the site is generally relatively level to moderately sloping to the south and southwest towards Jasper Road. However, the northern portion of the property abuts a terrace slope that extends north with a general gradient of approximately 2H:1V, and a slope height ranging from approximately 30 feet to 70 feet, being tallest on the eastern side of the property. Site elevations within the property boundaries range from approximately 510 to 580 feet above mean sea level (amsl). Based on our review of the Oregon Department of Geology and Mineral Industries (DOGAMI) state geohazard mapping, we understand that the north-facing slope has been identified as being at Moderate to High risk for landsliding, however, the state mapping has not identified any landslides within the site boundaries. The state mapping does however indicate the presence of a shallow landslide (Eugene No. 344) on the bluff located east of the property boundary. The mapped landslide has been recorded as a pre-historic (greater than 150 years old), debris slide/rotational slide, with a head scarp height of approximately 30 feet, and a failure depth of approximately 12 fe et. GeoPacific understands that the proposed development will consist of a multi-phase, 273-Lot residential subdivision supporting construction of single -family residential homes, retaining walls, new public streets, new underground utilities, and stormwater facilities. Preparation of site plans will be conducted in a phased approach. At this time the civil engineer has provided preliminary plans for phases 3 and 4, with theoretical layouts for phases 5 through 8. Specific analysis and geotechnical review of future grading plans may be conducted once they are prepared. Currently, we anticipate that the homes will be constructed with typical spread foundations and wood framing, with maximum structural loading on column footings and continuous strip footings on the order of 10 to 35 kips, and 2 to 4 kips respectively. Based on our review of the proposed grading for the initial phases we understand that cuts and fills will be conducted on the order of 10 feet or less. Preliminary Geotechnical Engineering Report Project No. 21-5865, Woodland Ridge Phases 3-8, Springfield, Oregon 21-5865, Woodland Ridge Phases 3-8 Geotechnical Report 2 Version 1.0, December 27, 2021 3.0 REGIONAL GEOLOGIC SETTING AND LANDSLIDE MAPPING Regionally, the subject site lies within the Willamette Valley/Puget Sound lowland, a broad structural depression situated between the Coast Range on the west and the Cascade Range on the east. A series of discontinuous faults subdivide the Willamette Valley into a mosaic of fault-bounded, structural blocks (Yeats et al., 1996). Uplifted structural blocks form bedrock highlands, while down- warped structural blocks form sedimentary basins. The Preliminary Geologic Map of the Springfield Quadrangle, Lane County, Oregon (Oregon Department of Geology and Mineral Industries, Open-File Report 0-06-07, Hladky, F.R. and McCaslin, G.R., 2006), indicates that the site is underlain by Pliocene to Pleistocene-aged (approximately 2.6 million to 11,000 years ago) terrace deposits consisting of silt, sand, and gravel deposited primarily by late Pleistocene glacial outburst flooding commonly referred to as the Missoula Flood Events, but also including glaciofluvial sediments derived from weathering of the Cascade Range located to the east (QTtg). 4.0 REGIONAL SEISMIC SETTING At least one major fault zone capable of generating damaging earthquakes are thought to exist in the vicinity of the subject site. These include the Cascadia Subduction Zone. 4.1 Cascadia Subduction Zone The Cascadia Subduction Zone is a 680-mile-long zone of active tectonic convergence where oceanic crust of the Juan de Fuca Plate is subducting beneath the North American continent at a rate of 4 cm per year (Goldfinger et al., 1996). A growing body of geologic evidence suggests that prehistoric subduction zone earthquakes have occurred (Atwater, 1992; Carver, 1992; Peterson et al., 1993; Geomatrix Consultants, 1995). This evidence includes: (1) buried tidal marshes recording episodic, sudden subsidence along the coast of northern California, Oregon, and Washington, (2) burial of subsided tidal marshes by tsunami wave deposits, (3) paleoliquefaction features, and (4) geodetic uplift patterns on the Oregon coast. Radiocarbon dates on buried tidal marshes indicate a recurrence interval for major subduction zone earthquakes of 250 to 650 years with the last event occurring 300 years ago (Atwater, 1992; Carver, 1992; Peterson et al., 1993; Geomatrix Consultants, 1995). The inferred seismogenic portion of the plate interface lies approximately along the Oregon Coast at depths of between 20 and 40 kilometers below the surface. 5.0 FIELD EXPLORATION AND SUBSURFACE CONDITIONS Our subsurface explorations for this report were conducted on August 31, September 1, and September 13, 2021. A total of twenty exploratory test pits (TP-1 through TP-20) were excavated at the site using a Case 580 Extendahoe backhoe with rock teeth subcontracted by GeoPacific to a maximum depth of approximately 16 feet bgs. In addition, two mud-rotary soil borings (B-1 and B-2) were drilled at the site to maximum depths of approximately 51.5 feet bgs. SPT (Standard Penetration Test) sampling was performed at regular intervals within the borings in general accordance with ASTM D1586 using a 2-inch outside diameter split-spoon sampler and a 140-pound hammer equipped with an auto-hammer mechanism. During the test, a sample is obtained by driving the sampler 18 inches into the soil at the target test depth with the hammer free -falling from a height of 30 inches. The number of blows for each 6 inches of penetration is recorded. The Standard Preliminary Geotechnical Engineering Report Project No. 21-5865, Woodland Ridge Phases 3-8, Springfield, Oregon 21-5865, Woodland Ridge Phases 3-8 Geotechnical Report 3 Version 1.0, December 27, 2021 Penetration Resistance (“N-Value”) of the soil is calculated as the number of blows required for the final 12 inches of penetration. If 50 or more blows are recorded within a single 6-inch interval, the test is terminated, and the blow count is recorded as 50 blows for the number of inches driven. This resistance, or N-Value, provides a measure of the relative density of granular soils and the relative consistency of cohesive soils. Explorations were conducted under the full-time observation of a GeoPacific geologist. During the explorations pertinent information including soil sample depths, stratigraphy, soil engineering characteristics, and groundwater occurrence was recorded. Soils were classified in accordance with the Unified Soil Classification System (USCS). Soil samples obtained from the explorations were placed in relatively air-tight plastic bags. At the completion of each test, the test pits were loosely backfilled with onsite soils. Soil borings were backfilled with bentonite chips. The approximate locations of the explorations are indicated on Figures 2 and 3. It should be noted that exploration locations were located in the field by pacing or taping distances from apparent property corners and other site features shown on the plans provided. As such, the locations of the explorations sh ould be considered approximate. Summary exploration logs are attached. The stratigraph ic contacts shown on the individual test pit logs represent the approximate boundaries between soil types. The actual transitions may be more gradual. The soil and groundwater conditions depicted are only for the specific dates and locations reported, and therefore, are not necessarily representative of other locations and times. Soil and groundwater conditions encountered in the exploration s are summarized below. 5.1 Soil Descriptions Topsoil: At the locations of our explorations the ground was surfaced primarily with grasses, blackberries, and coniferous trees. A topsoil horizon was observed to be present in the grassy portions of the site typically consisting of 6 to 8 inches of moderately organic Lean CLAY (OL-CL) containing fine roots. A topsoil horizon was observed to be present in the heavily wooded portions of the site typically consisting of 18 to 20 inches of moderately to highly organic Lean CLAY (OL-CL) containing fine roots. Interlayered Clayey GRAVEL, Gravelly CLAY, Gravelly SILT and Sand (Terrace Deposits): Underlying the topsoil and Fat CLAY soil types within our explorations, soils were observed to consist primarily of interlayered medium stiff to hard, moist, low plasticity, Lean CLAY, gravelly Lean CLAY, clayey GRAVEL, and Clayey GRAVEL with Sand (CL-GC-GP), containing abundant, subrounded, highly weathered to relatively un-weathered, gravel and cobble-sized aggregate. Heavy interlayering of silts and sands was also noted within the subsurface lithology. The soil types were observed to extend to the maximum depth of exploration, with a general decrease in weathering and increase in aggregate size with depth. Pocket penetrometer measurements conducted in the upper four feet of the ground surface indicated unconfined compressive strengths ranging from approximately 3.5 to 4.5 tons/ft2 (tsf). SPT N-values ranging from 5 to 43 were recorded within soil borings B-1 and B-2. Fat CLAY (CH): Underlying the topsoil layers at the locations of test pits TP-1, TP-2, TP-11, TP-12, TP-13, TP-14, and TP-16, soils were observed to consist of gray-brown-orange mottled, stiff to very stiff, moist, high plasticity, Fat CLAY (CH). The soil type was observed to be present at depth intervals ranging from approximately - 3 to -10 feet bgs within the noted explorations. Soils laboratory testing conducted on a representative sample collected from test pit TP-1 indicated that the soil type Preliminary Geotechnical Engineering Report Project No. 21-5865, Woodland Ridge Phases 3-8, Springfield, Oregon 21-5865, Woodland Ridge Phases 3-8 Geotechnical Report 4 Version 1.0, December 27, 2021 classified as Fat CLAY (CH), according to the USCS soil classification system, and as A-7-5(28), A-7-5(51), and A-7-5(72), according to AASHTO standards. Sieve analysis indicated 78 to 94 percent by weight passing the U.S. No. 200 sieve, and a moisture content of 39 to 40 percent. Atterberg Limit testing indicated a liquid limit of 70 to 101, and a plasticity index of 30 to 63. Expansive index testing (EI) was conducted on a representative sample collected from test pit TP-1 in accordance with the procedures of ASTM D4829. Expansive index testing indicated an expansive index of 143, which is considered to be very high expansive potential. A summary of the locations where expansive soils were encountered, thickness of the soil layer at specific test locations, soil type classification, and expansive index is presented in Table 1. Refer to attached figures and test pit logs for additional detail. Additional discussion regarding recommendations for areas where expansive soils will be encountered at the site is presented below in Section 5.2, Expansive Soils and Shrink Swell Potential; Section 7.1, Site Preparation Recommendations; Section 7.3, Engineered Fill; and Section 7.8, Spread Foundations. Table 1. Expansive Soils Test Pit Soil Type USCS Depth Layer Encountered (Feet bgs) Maximum Depth of Layer (Feet bgs) Thickness of Soil Layer (Feet) Plasticity Index Expansive Index ASTM D4829 TP-1 CH 3 12 9 63.6 143 TP-2 CH 6 12 6 - - TP-11 CH 6 - - 51.7 - TP-12 CH 3 7 4 - - TP-13 CH 3 7 4 - - TP-14 CH 4 8 4 - - TP-16 CH 4 - - - 5.2 Shrink-Swell Potential Primarily low plasticity, silt, clay, and granular soil types were encountered within our explorations. As described above, highly plastic, highly expansive Fat CLAY soils were encountered in some explorations and various depth intervals at the site existing in pockets located primarily in the southern portion of the property. Laboratory analysis indicated the near soil types generally displayed low plastic to non-plastic characteristics, however the top of the highly expansive Fat CLAY soil type is present at depths ranging from approximately 3 to 6 feet below the existing ground surface where encountered. In many portions of the site the separation distances from the highly expansive soil type to the existing elevations appears to be adequate to minimize the risk or concern associated with construction of foundations on highly expansive soil types, however if cuts are made in these areas it may reduce the separation distance from bottom of the house footings to the top of the clay layers, or expose the soil types. Based on our review of the proposed development plan it appears that homes may be constructed in areas underlain by highly expansive Fat CLAY soils. If engineered fill is placed in these areas to raise the existing elevations it would increase the separation distance from the clay soils to the bottom of the house footings. Once final grading is completed GeoPacific can assist the civil engineer in reviewing the achieved separation distances from the highly expansive soils to the proposed bottom of footings and provide lot by lot recommendations for addressing potential risks. Additional discussion regarding recommendations for areas where expansive soils Preliminary Geotechnical Engineering Report Project No. 21-5865, Woodland Ridge Phases 3-8, Springfield, Oregon 21-5865, Woodland Ridge Phases 3-8 Geotechnical Report 5 Version 1.0, December 27, 2021 will be encountered at the site is presented below in Section 7.1, Site Preparation Recommendations; Section 7.3, Engineered Fill; and Section 7.8, Spread Foundations. 5.3 Groundwater and Soil Moisture August 31, September 1, and September 13, 2021, observed soil moisture conditions were generally moist. Groundwater seepage was only encountered within test pit TP-17 at a depth of approximately 7 feet bgs. Based on our review of available well logs from the vicinity of the subject site we expect that static groundwater may be encountered at depths ranging from approximately 50 to 75 feet bgs, depending on ground surface elevation. Perched groundwater may be encountered in localized areas. Seeps and springs may exist in areas not explored and may become evident during site grading. Based on our observations of the location where groundwater is encountered, it appears that the water seepage may be originating from the neighboring subdivision located to the west of the property. 5.4 Infiltration Testing Soil infiltration testing was performed using the open-hole method within test pits TP-3, TP-11, and TP-16. The approximate locations of the subsurface explorations are indicated on Figures 2, and 3. The open-hole method was utilized and an approximate 2ftx2ft square area was excavated at the bottom of the test pit 1ft deep to conduct the testing in. The test locations were pre-saturated prior to testing. During testing the water level was measured to the nearest 0.01 foot (1/8 inch) from a fixed point, and the change in water level was recorded at regular intervals until three successive measurements showing a consistent infiltration rate were achieved. Table 2 summarizes the results of the infiltration testing. Infiltration rates have been reported without applying a factor of safety. Table 2: Summary of Infiltration Test Results Test Location Test Designation Depth (feet) Soil Type % Passing U.S. No 200 Sieve Infiltration Rate (inches/hr) Hydraulic Head Range (inches) Test Type TP-3 IT-1 7 GM 22.5 0.2 0-12 Open-Hole TP-11 IT-2 10 CH 84.2 0.1 0-12 Open-Hole TP-16 IT-3 6.5 CH 78.5 0 0-12 Open-Hole Infiltration rates of 0 to 0.2 inches per hour were measured at the locations and depths tested. In general, the subsurface soil profile displayed low infiltration capacity. Based upon the results of our testing it appears that stormwater infiltration systems may not be geotechnically feasible at the locations testing within the subject site, however, other portions of the site found to be underlain by sands and gravels may be feasible to construction infiltration systems. Additional exploration and testing of other locations can be conducted by GeoPacific if determined to be necessary. Due to the presence of steeply sloping areas in the northern portion of the site, we recommend a minimum setback distance from the top of slope of 200 feet for any proposed infiltration systems. Infiltration test methods and procedures attempt to simulate the as-built conditions of the planned disposal systems. However, due to natural variations in soil properties, actual infiltration rates may Preliminary Geotechnical Engineering Report Project No. 21-5865, Woodland Ridge Phases 3-8, Springfield, Oregon 21-5865, Woodland Ridge Phases 3-8 Geotechnical Report 6 Version 1.0, December 27, 2021 vary from the measured and/or recommended design rates. Infiltration rates presented in this report should not be applied to inappropriate or complex hydrological models such as a closed basin without extensive further studies. Evaluating environmental implications of stormwater disposal at this site are beyond the scope of this study. 6.0 LANDSLIDE HAZARD AND SLOPE STABILITY STUDY GeoPacific conducted a landslide hazard review and quantitative global slope stability study of the slope relative to the proposed development. For the purpose of evaluating slope stability at the subject site we: (1) conducted a review of available literature and published geologic mapping; (2) reviewed available LiDAR and landslide inventory mapping; (3) performed field reconnaissance and slope measurements, (4) conducted subsurface exploration at the property; (5) constructed geologic cross-sections of existing conditions, and post-construction conditions; and (6) conducted a quantitative slope stability analysis of the site under existing conditions, and post-construction conditions using the Slope/W program to determine appropriate geologic footing-to-slope setback distances. 6.1 Literature Review Topography at the site is generally relatively level to moderately sloping to the south and southwest towards Jasper Road. However, the northern portion of the property abuts a terrace slope that extends north with a general gradient of approximately 2H:1V, and a slope height ranging from approximately 30 feet to 70 feet, being tallest and steepest on the eastern side of the property. Site elevations within the property boundaries range from approximately 510 to 580 feet above mean sea level (amsl). The Preliminary Geologic Map of the Springfield Quadrangle, Lane County, Oregon (Oregon Department of Geology and Mineral Industries, Open-File Report 0-06-07, Hladky, F.R. and McCaslin, G.R., 2006), indicates that the site is underlain by Pliocene to Pleistocene -aged (approximately 2.6 million to 11,000 years ago) terrace deposits consisting of silt, sand, and gravel deposited primarily by late Pleistocene glacial outburst flooding commonly referred to as the Missoula Flood Events, but also including glaciofluvial sediments derived from weathering of the Cascade Range located to the east (QTtg). Based on our review of the Oregon Department of Geology and Mineral Industries (DOGAMI) state geohazard mapping, we understand that the site contains areas identified as being at Moderate to High risk for landsliding, however, the state mapping has not identified any landslides within the site boundaries. The highest risk areas are located in the northern portion of the property. The DOGAMI Oregon HazVu: Statewide Geohazards Viewer indicates that the subject site is located in an area considered at risk for strong ground shaking, and low risk for soil liquefaction during an earthquake. Preliminary Geotechnical Engineering Report Project No. 21-5865, Woodland Ridge Phases 3-8, Springfield, Oregon 21-5865, Woodland Ridge Phases 3-8 Geotechnical Report 7 Version 1.0, December 27, 2021 DOGAMI Hazvu Landslide Hazard Mapping. Indicating Moderate to High Risk for Landsliding. However, the state mapping does indicate the presence of a shallow landslide (Eugene No. 344) on the bluff located east of the property boundary. The mapped landslide has been recorded as a pre-historic (greater than 150 years old), debris slide/rotational slide, with a head scarp height of approximately 30 feet, and a failure depth of approximately 12 feet. DOGAMI Hazvu Landslide Inventory Mapping. Brown Hatching Indicates Area of Identified Sliding (Eugene No. 344). Preliminary Geotechnical Engineering Report Project No. 21-5865, Woodland Ridge Phases 3-8, Springfield, Oregon 21-5865, Woodland Ridge Phases 3-8 Geotechnical Report 8 Version 1.0, December 27, 2021 6.2 LiDAR Review We reviewed available LiDAR imagery of the site (Figure 4, and below). The LiDAR imagery generally indicates smooth, planar geomorphology across the majority of the site. The northern margin of the property is defined by the north-sloping bluff clearly visible at the northern portion of the site. While the state mapping indicates a moderate to high risk of landsliding on the bluff, our review of the LiDAR imagery generally indicates a planar geomorphology and west of the identified slide area comprising Eugene No. 344. Areas of recent or historic erosion, sloughing, slumping, or rotation sliding do not appear to be present. DOGAMI Hazvu LiDAR. Northern Bluff Visible, with Eugene No 344 Located on Eastern Side of Property. 6.3 Field Reconnaissance Subsurface Exploration We conducted field reconnaissance and subsurface soil exploration at the site to observe geomorphic features and subsurface soil conditions, and to assess the northern portion of the development area for evidence of potential slope instability. Our visual inspection of the mapped moderate to high risk landslide areas was primarily focused in the northern portion of the property and on the north-facing slope face. No tension cracks or slumping were observed at the time of our study. Vegetation appeared to be native and undisturbed on the slope. The coniferous trees were observed to be large and growing with straight trunks. We conducted subsurface exploration at the site consisting of twenty excavator test pits, and two soil borings to maximum depths of 51.5 feet bgs. See Figures 2 and 3 for the approximate subsurface exploration locations and the attached subsurface logs for detail. Soils encountered within our subsurface explorations primarily consisted of interlayered medium stiff to hard, moist, low plasticity, Lean CLAY, gravelly Lean CLAY, clayey GRAVEL, and Clayey GRAVEL with Sand (CL-GC-GP), containing abundant, subrounded, highly weathered to relatively un-weathered, gravel and cobble- sized aggregate. Heavy interlayering of silts and sands was noted within the subsurface lithology. SPT N-values blow counts recorded within the soil layers near the top of the slope ranged from 5 to 43. Evidence of slip planes or bedding planes was not detected or observed during subsurface exploration. Groundwater was not encountered within our soil borings. In general, we encountered medium dense to dense, weathered terrace deposits, with a decrease observed in the degree of weathering with depth. Preliminary Geotechnical Engineering Report Project No. 21-5865, Woodland Ridge Phases 3-8, Springfield, Oregon 21-5865, Woodland Ridge Phases 3-8 Geotechnical Report 9 Version 1.0, December 27, 2021 6.4 Quantitative Slope Stability Modeling GeoPacific conducted a quantitative analysis of global slope stability for the north-facing slope considering existing conditions, and post-construction conditions, in order to determine appropriate minimum footing-to-slope setback recommendations for the proposed homes under both static and pseudostatic conditions. Seismic design values were obtained for the site using the ATC Hazards by Location 2021 Seismic Design Maps Summary Report. We constructed geologic cross-sections A to D through the north-facing slope to model existing conditions, and conceptual post-construction conditions at the property. The locations of the cross-sections are indicated on Figure 3B. Quantitative slope stability modeling and analyses were performed using the SLOPE/W 2019 R2, version 10.1.0.18696 computer program developed by Geo-Slope International of Calgary, Canada. This numerical analysis program utilizes a two-dimensional limiting equilibrium method to calculate the factor of safety of a potential slip surface and incorporates search routines to identify the most critical potential failure surfaces for the cases analyzed. Factors of safety were calculated using the Morgenstern-Price method of slices. 6.4.1 Existing Conditions Analysis The existing conditions at the site were modeled as a three-layer system representative of soil conditions encountered in our subsurface explorations. Slope topography, subsurface geometry, depth to groundwater, and other conditions modeled in the analyses are based on site plans provided by the civil engineer, the results of our subsurface soil explorations, review of available LiDAR imagery, and our field measurements. A static and pseudostatic analysis was conducted on the existing conditions models. *Please note that the post-construction models include evaluation of anticipated cuts and fills associated with the proposed grading, while the existing conditions models are estimates of the existing soil conditions, and not necessarily reflective of the final site conditions or recommended footing-to-slope setbacks discussed in Section 6.4.2, Post-Construction Analysis. For stability calculations, the potential failure mode was considered as circular sliding along a basal shear surface using entry and exit analysis. Shear strength parameters used in the models were selected based on soil conditions encountered within soil boring explorations, SPT N-value correlations, and our local experience with similar soil and geologic conditions. The internal angle of friction of each soil type was estimated based on empirical correlations of soil stiffness, soil type, and vertical effective stress (adapted from DeMello, 1971, Coduto, 2001, Figure 4.11). The assumed values of internal angle of friction and cohesion utilized in the analysis are conservative and consider saturated conditions. The soil parameters assumed in the stability calculations are summarized in Table 3. The results of our slope stability analyses for existing conditions are summarized in Table 4. Slope stability analyses cross-sections are presented as attachments to this report. Factors of safety against slope instability are considered acceptable for structures when greater than 1.5 for the static condition, and greater than 1.1 for the seismic condition. Factors of safety against slope instability are considered acceptable for property lines when greater than 1.25 for the static condition, and greater than 1.0 for the seismic condition. Preliminary Geotechnical Engineering Report Project No. 21-5865, Woodland Ridge Phases 3-8, Springfield, Oregon 21-5865, Woodland Ridge Phases 3-8 Geotechnical Report 10 Version 1.0, December 27, 2021 Table 3: Summary of Estimated Soil Strength Parameters: Existing Conditions Geologic Unit Wet Unit Weight (pcf) Friction Angle Cohesion (psf) Lean CLAY (CL) 120 28° 200 Silty/Clayey GRAVEL (GM) 125 30° 100 Silty & Poorly Graded Gravel (GP-GM) 125 36° 25 Table 4: Summary of Existing Condition Slope Stability Factors of Safety Condition Analyzed Calculated Factors of Safety Existing Conditions Static Seismic Section A to A’ – Lot 4 PGAM = 0.392g ½ PGA = 0.196g 1.5 At 30-Foot Setback from Top of Slope 1.1 At 50-Foot Setback from Top of Slope Section B to B’ – Lot 25 PGAM = 0.392g ½ PGA = 0.196g 1.5 At 15-Foot Setback from Top of Slope 1.1 At 25-Foot Setback from Top of Slope Section C to C’ – Lot 20 PGAM = 0.392g ½ PGA = 0.196g 1.5 At 35-Foot Setback from Top of Slope 1.1 At 35-Foot Setback from Top of Slope Section D to D’ – Lot 14 PGAM = 0.392g ½ PGA = 0.196g 1.5 At 25-Foot Setback from Top of Slope 1.1 At 40-Foot Setback from Top of Slope 6.4.2 Post-Construction Analysis The post-construction conditions at the site were modeled as a three-layer system representative of soil conditions encountered in our subsurface explorations. Slope topography, subsurface geometry, depth to groundwater, proposed home location, depths and extents of engineered cuts and fills, and other conditions modeled in the analyses are based on site plans provided by the civil engineer, the results of our subsurface soil explorations, review of available LiDAR imagery, and our field measurements. A building surcharge of 250 psf was applied while considering applied foundation loading. A static and pseudostatic analysis was conducted on the post-construction conditions model to determine slope setback distances needed to achieve acceptable footing-to-slope setbacks for the proposed homes. For stability calculations, the potential failure mode was considered as circular sliding along a basal shear surface using entry and exit analysis. Shear strength parameters used in the models were selected based on soil conditions encountered within soil boring explorations, SPT N-value correlations, and our local experience with similar soil and geologic conditions. The internal angle of friction of each soil type was estimated based on empirical correlations of soil stiffness, soil type, and Preliminary Geotechnical Engineering Report Project No. 21-5865, Woodland Ridge Phases 3-8, Springfield, Oregon 21-5865, Woodland Ridge Phases 3-8 Geotechnical Report 11 Version 1.0, December 27, 2021 vertical effective stress (adapted from DeMello, 1971, Coduto, 2001, Figure 4.11). The assumed values of internal angle of friction and cohesion utilized in the analysis are conservative and consider saturated conditions. The soil parameters assumed in the stability calculations are summarized in Table 5. The results of our slope stability analyses for post-construction conditions are summarized in Table 6. Slope stability analyses cross-sections are presented as attachments to this report. Factors of safety against slope instability are considered acceptable for structures when greater than 1.5 for the static condition, and greater than 1.1 for the seismic condition. Factors of safety against slope instability are considered acceptable for property lines when greater than 1.25 for the static condition, and greater than 1.0 for the seismic condition. Table 5: Summary of Estimated Soil Strength Parameters: Post-Construction Conditions Geologic Unit Wet Unit Weight (pcf) Friction Angle Cohesion (psf) Lean CLAY (CL) 120 28° 200 Silty/Clayey GRAVEL (GM) 125 30° 100 Silty & Poorly Graded Gravel (GP-GM) 125 36° 25 Table 6: Summary of Post-Construction Slope Stability Factors of Safety Condition Analyzed Calculated Factors of Safety Post-Construction: Proposed Grading and Footing Locations Static Seismic Section A to A’ Future Lot Phase 7 PGAM = 0.392g ½ PGA = 0.196g 1.8 At 50-Foot Setback from Top of Slope *35-Foot Setback from Property Line 1.1 At 50-Foot Setback from Top of Slope *35-Foot Setback from Property Line Section B to B’ Phase 4 Lot 25 PGAM = 0.392g ½ PGA = 0.196g 1.7 At 55-Foot Setback from Top of Slope 15-Foot Setback from Property Line 1.2 At 60-Foot Setback from Top of Slope 15-Foot Setback from Property Line Section C to C’ Phase 4 Lot 20 PGAM = 0.392g ½ PGA = 0.196g 1.9 At 64-Foot Setback from Top of Slope 15-Foot Setback from Property Line 1.2 At 64-Foot Setback from Top of Slope 15-Foot Setback from Property Line Section D to D’ Phase 4 Lot 14 PGAM = 0.392g ½ PGA = 0.196g 1.6 At 40-Foot Setback from Top of Slope 15-Foot Setback from Property Line 1.1 At 40-Foot Setback from Top of Slope 15-Foot Setback from Property Line *Indicates additional recommended footing-to-slope setback than proposed. See Figure 3B for geotechnical setback Preliminary Geotechnical Engineering Report Project No. 21-5865, Woodland Ridge Phases 3-8, Springfield, Oregon 21-5865, Woodland Ridge Phases 3-8 Geotechnical Report 12 Version 1.0, December 27, 2021 6.5 Slope Stability Analysis Summary Our quantitative slope stability analysis relative to cross-sections A through D included review and assessment of the existing topography, proposed engineered cuts and fill, and proposed home locations based on review of preliminary grading plans and proposed foundation envelope dimensions provided by the project civil engineer. Based on our review of the proposed preliminary grading, the top of the slope will be cut up to approximately 10 feet which will effectively move the top of slope location north from the current location. The post-grading horizontal change in top of slope location is reflected on the attached cross-sections, and our recommendations regarding appropriate footing-to-slope setback distances are relative to the top of slope location and the proposed foundation locations. We understand that the rear footings of the homes have been proposed to be located 15 feet south of the proposed northern property lines. While assessing the proposed cuts to the northern slope and the proposed property line and foundation locations, the results of our quantitative slope stability analysis indicate adequate factors of safety against slope instability for the proposed construction under both static and pseudostatic conditions at the locations of cross-sections B-B’, C to C’, and D to D’. Static and pseudostatic factors of safety against slope instability were less than 1.5, and 1.1 for cross-section A to A’ at the proposed foundation locations. In order to provide adequate factors recommend the following footing-to-slope setback distances for each cross-section: • Cross-Section A to A’: 50 feet south of the new top of slope, 35 feet south of the property line. This recommended setback results in an approximate 20-foot setback from the current proposed foundation location, relative to the northern lots in the future Phase 7. The recommended geotechnical footing-to-slope setback line is indicated on Figure 3B. This analysis also assumes that no additional engineered fill or structures will be placed within the setback zone or beyond the proposed foundation location. In addition, we recommend a 200-foot minimum setback for stormwater infiltration systems as measured from the surveyed top of slope along the northern property margin. 7.0 CONCLUSIONS AND RECOMMENDATIONS Our site investigation and grading plan review indicates that the proposed construction appears to be geotechnically feasible, provided that the recommendations of this report are incorporated into the design and construction phases of the project. The primary geotechnical concerns associated with development at the site are: • Minimum geotechnical foundation footing-to-slope setbacks should be maintained as indicated in Section 6.0, Landslide Hazard and Slope Stability Study. Engineered fill, structures, retaining walls, irrigation systems, and pools should not be placed beyond the proposed geotechnical foundation setback line without additional case-by-case study. • Highly expansive soil types were encountered in some portions of the site. Home foundations should maintain a minimum separation distance of at least 42 inches from the top of highly expansive soil layers, as measured from the bottom of the footings. Recommendations for areas where expansive soils will be encountered at the site are presented below in Section 7.1, Site Preparation Recommendations; Section 7.3, Engineered Fill; and Section 7.8, Spread Foundations. Preliminary Geotechnical Engineering Report Project No. 21-5865, Woodland Ridge Phases 3-8, Springfield, Oregon 21-5865, Woodland Ridge Phases 3-8 Geotechnical Report 13 Version 1.0, December 27, 2021 7.1 Site Preparation Recommendations As noted above, highly expansive Fat CLAY soils were encountered in some of the test pit explorations of the site (see Table 1). Recommendations for mitigating risks associated with construction in areas underlain by highly expansive soils may vary depending on the thickness of the layers, depth to the layers, and the cuts and fills proposed with the grading plan. We recommend that a minimum separation distance of at least 42 inches should be maintained between the bottom elevations of proposed foundations and highly expansive soils. In order to achieve a minimum separation distance between the bottom elevations of proposed foundations and expansive soils of at least 42 inches, we recommend that the following options be considered: • Adequate separation distance from the top of the expansive soil layers may be achieved through placement of engineered fill with low expansive soil types. • Adequate separation distance from the top of the expansive soil layers may be achieved by over-excavating to a depth of at least 42 inches below the bottom elevations of the proposed foundations and replacing with low expansivity engineered fill soil types, or granular soil types; • It may be feasible to cement amend the highly expansive soil types to reduce the expansive potential to acceptable expansion potential limits. A minimum cement content of 6 percent should be assumed for planning purposes, and verified through laboratory testing prior to, and during cement treatment to confirm that the assumed percent of cement will reduce the expansive index to 90 or lower (medium expansion potential or less). (see Section 7.4, Cement Amending Procedures); We recommend that prior to beginning of site grading, the earthworks contractor, civil engineer, and geotechnical engineer meet to discuss approaches to mitigating the risks associated with construction on expansive soils, and to carefully consider options for various portions of the project in relation to the proposed grading plan. We anticipate that a combination of the above listed recommendations will be implemented depending on the specific condition of each lot. Additional subsurface exploration, and expansive index testing should be conducted during field work to adjust recommendations as needed. Further careful review by the project civil engineer of the depths of expansive soils and depths to bedrock at a specific location in relation to the prop osed grading plan may indicate areas where the proposed grading may be adjusted in order to accommodate a means of mitigating the expansive soil risk. Areas of proposed construction and areas to receive fill should be cleared of any organic and inorganic debris, undocumented fill soils, and/or loose stockpiled soils. Inorganic debris and organic materials from clearing should be removed from the site. Organic-rich soils and root zones should then be stripped from construction areas of the site or where engineered fill is to be placed. Depth of stripping of existing topsoil is estimated to average approximately 6 to 8 inches in grassy areas, and be as much as 20 inches in heavily wooded portions of the site. The final depth of soil removal will be determined during site inspection after the stripping/excavation has been performed. Stripped topsoil should be removed from areas proposed for placement of Preliminary Geotechnical Engineering Report Project No. 21-5865, Woodland Ridge Phases 3-8, Springfield, Oregon 21-5865, Woodland Ridge Phases 3-8 Geotechnical Report 14 Version 1.0, December 27, 2021 engineered fill. Any remaining topsoil should be stockpiled only in designated areas and stripping operations should be observed and documented by the geotechnical engineer or his representative. Where encountered, undocumented fills and any subsurface structures (dry wells, basements, swimming pools, driveway and landscaping fill, old utility lines, septic leach fields, etc.) should be completely removed and the excavations backfilled with engineered fill. Fill may exist where homes and drive areas were once present, particularly in the northeastern portion of the site. We recommend that areas proposed for placement of engineered fill are scarified and recompacted prior to placement of structural fill. The areas should be prepared by removing highly organic soil layers which contain abundant root concentration, or organic content in excess of approximately 4 to 5 percent by weight. Prior to placement of engineered fill, the underlying soils be over-excavated, ripped, aerated to optimum moisture content, and recompacted to project specifications for engineered fill as determined by the Standard Proctor (ASTM D698). Areas proposed to be left at grade may require additional over -excavation of foundation areas in order to reach soils which will provide adequate bearing support for the proposed foundations. It is unlikely that site earthwork will be impacted by shallow groundwater, however native soils are moisture sensitive and may be difficult to handle during periods of wet weather. Stabilization of subgrade soils will require aeration and re-compaction. If subgrade soils are found to be difficult to stabilize, over-excavation, placement of granular soils, or cement treatment of subgrade soils may be feasible options. GeoPacific should be onsite to observe preparation of subgrade soil conditions prior to placement of engineered fill. 7.2 Keyways, Benching, and Subdrains for Fill Slopes Keying and benching will be required on this project where engineered fills are proposed on hillsides. Engineered fill placed on existing sloped areas inclining at, or steeper than an app roximately twenty percent grade should be constructed on a keyway and benches in accordance with the typical designs shown in the attached Fill Slope Detail (Figure 6). Keyways should have a minimum depth of three feet on the downhill size, and a minimum width of ten feet. Keyways should be excavated at the toe of the fill slope and extend perpendicular to the downslope direction. Additional removal of weakened or soft soils may be required depending on the conditions observed during construction. Benches and keyways should be roughly horizontal in the down slope direction, by may slope up to a 10 percent grade along a topographic contour. Keyways sloping more than a fifteen percent grade along a topographic contour should be benched or configured as approv ed by the geotechnical engineer or his designated representative. Actual determination and dimensions of keyways should be decided once final planning is complete, and under the direction of the geotechnical engineer. If groundwater seepage is observed during excavation, keyways should include a subdrain consisting of a minimum 4-inch-diameter, ADS Heavy Duty Grade (or equivalent), perforated plastic pipe enveloped in a minimum of 4 cubic feet per lineal foot of 2”- ½”, open-graded gravel drain rock wrapped with geotextile filter fabric (Mirafi 140N or equivalent). A minimum 0.5 percent gradient should be maintained throughout all subdrain pipes and outlets. GeoPacific should inspect keyways, subdrains and benching prior to fill placement. Subdrains may be eliminated at the discretion of the geotechnical engineer. Preliminary Geotechnical Engineering Report Project No. 21-5865, Woodland Ridge Phases 3-8, Springfield, Oregon 21-5865, Woodland Ridge Phases 3-8 Geotechnical Report 15 Version 1.0, December 27, 2021 7.3 Engineered Fill Based on communication with the civil engineer and our review of the proposed grading we understand that cuts and fills will be conducted on the order of 10 feet or less. All grading for the proposed construction should be performed as engineered grading in accordance with the applicable building code at the time of construction with the exceptions and additions noted herein. Site grading should be conducted in accordance with the requirements outlined in the 2018 International Building Code (IBC), and 2019 Oregon Structural Specialty Code (OSSC), Chapter 18 and Appendix J. Areas proposed for fill placement should be prepared as described in Section 7.1, Site Preparation Recommendations. Surface soils should then be scarified and recompacted prior to placement of structural fill. Site preparation, soil stripping, and grading activities should be observed and documented by a geotechnical engineer or his representative. Proper test frequency and earthwork documentation usually requires daily observation and testing during stripping, rough grading, and placement of engineered fill. Onsite native soils, except the Fat CLAY soil type, appear to be suitable for use as engineered fill. Soils containing greater than 5 percent organic content should not be used as structural fill. Imported fill material must be approved by the geotechnical engineer prior to being imported to the site. Oversize material greater than 6 inches in size should not be used within 3 feet of foundation footings, and material greater than 12 inches in diameter should not be used in engineered fill. Fat CLAY soils displaying high expansive potential are not considered suitable for use as engineered fill without lime or cement treatment. Cement treatment of expansive soils may be considered to reduce the expansive potential to within acceptable limits for construction of homes. A minimum cement content of 6 percent should be assumed for planning purposes, and verified through laboratory testing prior to, and during cement treatment to confirm that the assumed percent of cement will reduce the expansive index to 90 or lower (medium expansion potential or less). Recommendations for conducting cement amending are presented below in Section 7.4, Cement Amending Procedures. Engineered fill should be compacted in horizontal lifts not exceeding 12 inches using standard compaction equipment. We recommend that engineered fill be compacted to at least 95 percent of the maximum dry density determined by ASTM D698 (Standard Proctor) or equivalent. Field density testing should conform to ASTM D2922 and D3017, or D1556. All engineered fill should be observed and tested by the project geotechnical engineer or his representative. Typically, one density test is performed for at least every 2 vertical feet of fill placed or every 500 yd3, whichever requires more testing. Because testing is performed on an on-call basis, we recommend that the earthwork contractor be held contractually responsible for test scheduling and frequency. Site earthwork may be impacted by shallow groundwater, soil moisture and wet weather conditions. Earthwork in wet weather would likely require extensive use of additional crushed aggregate, cement or lime treatment, or other special measures, at considerable additional cost compared to earthwork performed under dry-weather conditions. Preliminary Geotechnical Engineering Report Project No. 21-5865, Woodland Ridge Phases 3-8, Springfield, Oregon 21-5865, Woodland Ridge Phases 3-8 Geotechnical Report 16 Version 1.0, December 27, 2021 7.4 Cement Amending Procedures This section provides recommendations for conducting cement amending should the method of subgrade stabilization, or reduction of expansive potential in highly expansive soils be incorporated into project design. The moisture sensitive subgrade soils make the site a difficult wet weather construction project. Wet weather construction recommendations are provided below. The client and contractor sho uld be prepared that wet weather construction may be risky and costly. We anticipate that cement treated soils will primarily consist of Fat CLAY. A minimum cement content of 6 percent by weight should be assumed for planning purposes, and verified throug h laboratory testing prior to, and during cement treatment to confirm that the assumed percent of cement will reduce the expansive index to 90 or lower (medium expansion potential or less). Actual percentages of cement required to achieve an adequate reduction in expansive index and increase in design strength should ultimately be determined by additional expansive index lab testing on soils collected from the fill zones, and the soil moisture content at the time of placement. Based on the results of additional testing during construction, it may be determined that additional cement content is needed in some areas. For planning purposes, the amount of cement used during treatment should be based on an assumed soil dry unit weight of 100 pounds per cubic foot for fine- grained soils. GeoPacific should evaluate the expansive index and moisture content of the fill soils before cement amendment. We recommend that the soil is moisture conditioned to at least 5 percent over optimum before being cement amendment. The amount of cement used may need to be increased or adjusted depending on the soil moisture content, particularly if soils are in excess of 10 percent over optimum moisture content. Portland cement content should not exceed 8 percent without prior approval. Cement amendment should be conducted with a maximum lift thickness of 12 inches. Cement amending operations should not be conducted during periods of heavy rainfall, or when the outside temperature is less than 40 degrees Fahrenheit. Following adequate placement and tilling of cement amended subgrade soils, a static, sheep’s-foot compactor should immediately be utilized to thoroughly compact the cement amended fill to at least 95 percent of the maximum dry density determined by ASTM D558 (Standard Test Method for Moisture-Density Unit Weight Relations of Soil-Cement Mixtures). A vibratory compactor is not recommended because it may further disturb the existing subgrade soils. During placement of cement amended fill soils, density testing should be performed to verify compliance with project specifications. Generally, one compaction test is performed for each vertical foot of cement amended engineered fill placed, and for every 100 to 200 linear feet within the alignment. Field density testing should conform to ASTM D6938, D2922, and D3017. Soil-cement compression test specimens of cement amended soils may be obtained and tested in the soil laboratory in accordance with ASTM D558 -04 if desired. A compressive strength in the range of 150 to 400 psi as determined by ASTM D 1633 Method A should ideally be achieved. The contractor should avoid impacting treated soils for a minimum period of 4 to 5 days to allow the cement to cure prior to subjecting the subgrade to construction traffic. After the initial cur e period, a proof-roll should be observed prior to routing construction traffic over cement treated areas. Preliminary Geotechnical Engineering Report Project No. 21-5865, Woodland Ridge Phases 3-8, Springfield, Oregon 21-5865, Woodland Ridge Phases 3-8 Geotechnical Report 17 Version 1.0, December 27, 2021 Impacting the treated base with heavy equipment prior to final cure of the treated soils could reduce final cure strengths and soft areas may develop. The primary risk associated with cement treatment of soils is that there is a potential for soft areas to develop following treatment if there in inadequate cement content added to the soil, blending of cement, or compaction of treated soils. Also, soft areas may develop where soils which may have been disturbed underlying the area of treatment are not adequately removed or treated. It is possible that even after careful treatment with recommended percentages, soft areas may still be present which would require additional over-excavation. 7.5 Excavating Conditions and Utility Trench Backfill We anticipate that onsite soils can generally be excavated using conventional heavy equipment. Bedrock was not encountered within subsurface explorations which extended to a maximum depth of approximately 51.5 feet bgs. Maintenance of safe working conditions, including temporary excavation stability, is the responsibility of the contractor. Actual slope inclinations at the time of construction should be determined based on safety requirements and actual soil and groundwater conditions. All temporary cuts in excess of 4 feet in height should be sloped in accordance with U.S. Occupational Safety and Health Administration (OSHA) regulations (29 CFR Part 1926) or be shored. The existing native soils primarily classify as Type C Soil and temporary excavation side slope inclinations as steep as 1.5H:1V may be assumed for planning purposes. These cut slope inclinations are applicable to excavations above the water table only. Shallow, perched groundwater may be encountered at the site and should be anticipated in excavations and utility trenches. Vibrations created by traffic and construction equipment may cause some caving and raveling of excavation walls. In such an event, lateral support for the excavation walls should be provided by the contractor to prevent loss of ground support and possible distress to existing or previously constructed structural improvements. Underground utility pipes should be installed in accordance with the procedures specified in ASTM D2321 and City of Springfield standards. We recommend that structural trench backfill be compacted to at least 95 percent of the maximum dry density obtained by the Modified Proctor (ASTM D1557, AASHTO T-180) or equivalent. Initial backfill lift thicknesses for a ¾”-0 crushed aggregate base may need to be as great as 4 feet to reduce the risk of flattening underlying flexible pipe. Subsequent lift thickness should not exceed 1 foot. If imported granular fill material is used, then the lifts for large vibrating plate-compaction equipment (e.g. hoe compactor attachments) may be up to 2 feet, provided that proper compaction is being achieved and each lift is tested. Use of large vibrating compaction equipment should be carefully monitored near existing structures and improvements due to the potential for vibration-induced damage. Adequate density testing should be performed during construction to verify that the recommended relative compaction is achieved. Typically, at least one density test is taken for every 4 vertical feet of backfill on each 100-lineal-foot section of trench. Preliminary Geotechnical Engineering Report Project No. 21-5865, Woodland Ridge Phases 3-8, Springfield, Oregon 21-5865, Woodland Ridge Phases 3-8 Geotechnical Report 18 Version 1.0, December 27, 2021 7.6 Erosion Control Considerations During our field exploration program, we did not observe soil and topographic conditions which are considered highly susceptible to erosion across the majority of the site. However, the riverbank extending to the Molalla River on the southern margin of the property displayed evidence of recent erosion, particularly along the southeastern edge of the property. Assuming the recommended geotechnical setbacks for construction are implemented into project planning, the primary concern regarding erosion potential will occur during construction in areas that have been stripped of vegetation. Erosion at the site during construction can be minimized by implementing the project erosion control plan, which should include judicious use of straw waddles, fiber rolls, and silt fences. If used, these erosion control devices should remain in place throughout site preparation and construction. Erosion and sedimentation of exposed soils can also be minimized by quickly re-vegetating exposed areas of soil, and by staging construction such that large areas of the project site are not denuded and exposed at the same time. Areas of exposed soil requiring immediate and/or temporary protection against exposure should be covered with either mulch or erosion control netting/blankets. Areas of exposed soil requiring permanent stabilization should be seeded with an approved grass seed mixture, or hydroseeded with an approved seed-mulch-fertilizer mixture. 7.7 Wet Weather Earthwork Soils underlying the site are likely to be moisture sensitive and will be difficult to handle or traverse with construction equipment during periods of wet weather. Earthwork is typically most economical when performed under dry weather conditions. Earthwork performed during the wet-weather season will require expensive measures such as cement treatment or imported granular material to compact areas where fill may be proposed to the recommended engineering specifications. If earthwork is to be performed or fill is to be placed in wet weather or under wet conditions when soil moisture content is difficult to control, the following recommendations should be incorporated into the contract specifications. • Earthwork should be performed in small areas to minimize exposure to wet weather. Excavation or the removal of unsuitable soils should be followed promptly by the placement and compaction of clean engineered fill. The size and type of construction equipment used may have to be limited to prevent soil disturbance. Under some circumstances, it may be necessary to excavate soils with a backhoe to minimize subgrade disturbance caused by equipment traffic; • The ground surface within the construction area should be graded to promote run-off of surface water and to prevent the ponding of water; • Material used as engineered fill should consist of clean, granular soil containing less than 5 percent passing the No. 200 sieve. The fines should be non-plastic. Alternatively, cement treatment of on-site soils may be performed to facilitate wet weather placement; • The ground surface within the construction area should be sealed by a smooth drum vibratory roller, or equivalent, and under no circumstances should be left uncompacted and exposed to moisture. Soils which become too wet for compaction should be removed and replaced with clean granular materials; Preliminary Geotechnical Engineering Report Project No. 21-5865, Woodland Ridge Phases 3-8, Springfield, Oregon 21-5865, Woodland Ridge Phases 3-8 Geotechnical Report 19 Version 1.0, December 27, 2021 • Excavation and placement of fill should be observed by the geotechnical engineer to verify that all unsuitable materials are removed and suitable compaction and site drainage is achieved; and • Geotextile silt fences, straw waddles, and fiber rolls should be strategically located to control erosion. If cement or lime treatment is used to facilitate wet weather construction, GeoPacific should be contacted to provide additional recommendations and field monitoring. 7.8 Spread Foundations GeoPacific understands that the proposed development will consist of a multi-phase, 273-Lot residential subdivision supporting construction of single-family residential homes. We anticipate that the homes will be constructed with typical spread foundations and wood framing, with maximum structural loading on column footings and continuous strip footings on the order of 10 to 35 kips, and 2 to 4 kips respectively. Based on our review of the proposed grading we understand that cuts and fills will be conducted on the order of 10 feet or less. As noted above, Fat CLAY soils displaying very high expansive potential were encountered in some portions of the site and are considered unsuitable for construction of structures without remediation. Recommendations for mitigating risks associated with construction on expansive soils may vary depending on the thickness of the layers, and the cuts and fills proposed with the grading plan. Section 7.1, Site Preparation Recommendations; and Section 7.3, Engineered Fill. A minimum separation distance of at least 42 inches should be maintained between the bottom elevations of proposed foundations and highly expansive soils. Assuming our recommendations are incorporated in the project the proposed structures may be supported on shallow foundations bearing on stiff, native soils and/or engineered fill, appropriately designed and constructed as recommended in this report. Foundation design, construction, and setback requirements should conform to the applicable building code at the time of construction. For maximization of bearing strength and protection against frost heave, spread footings should be embedded at a minimum depth of 12 inches below exterior grade. If soft soil conditions are encountered at footing subgrade elevation, they should be removed and replaced with compacted crushed aggregate. The anticipated allowable soil bearing pressure is 1,500 lbs/ft2 for footings bearing on competent, native soil and/or engineered fill. The recommended maximum allowable bearing pressure may be increased by 1/3 for short-term transient conditions such as wind and seismic loading. F or loads heavier than 35 kips, the geotechnical engineer should be consulted. If heavier loads than described above are proposed, it may be necessary to over-excavate point load areas and replace with additional compacted crushed aggregate to achieve a higher allowable bearing capacity. The coefficient of friction between on-site soil and poured-in-place concrete may be taken as 0.42, which includes no factor of safety. The maximum anticipated total and differential footing movements (generally from soil expansion and/or settlement) are 1 inch and ¾ inch over a span of 20 feet, respectively. We anticipate that the majority of the estimated settlement will occur during construction, as loads are applied. Excavations near structural footings should not extend within a 1H:1V plane projected downward from the bottom edge of footings. Preliminary Geotechnical Engineering Report Project No. 21-5865, Woodland Ridge Phases 3-8, Springfield, Oregon 21-5865, Woodland Ridge Phases 3-8 Geotechnical Report 20 Version 1.0, December 27, 2021 Footing excavations should penetrate through topsoil and any disturbed soil to competent subgrade that is suitable for bearing support. All footing excavations should be trimmed neat, and all loose or softened soil should be removed from the excavation bottom prior to placing reinforcing steel bars. Due to the moisture sensitivity of on-site native soils, foundations constructed during the wet weather season may require over-excavation of footings and backfill with compacted, crushed aggregate. Our recommendations are for residential construction incorporating raised wood floors and conventional spread footing foundations. After site development, a Final Soil Engineer’s Report should either confirm or modify the above recommendations. 7.9 Concrete Slabs-on-Grade Preparation of areas beneath concrete slab-on-grade floors should be performed as described in Section 7.1, Site Preparation Recommendations and Section 7.8, Spread Foundations. Care should be taken during excavation for foundations and floor slabs, to avoid disturbing subgrade soils. If subgrade soils have been adversely impacted by wet weather or otherwise disturbed, the surficial soils should be scarified to a minimum depth of 8 inches, moisture conditioned to within about 3 percent of optimum moisture content and compacted to engineered fill specifications. Alternatively, disturbed soils may be removed and the removal zone backfilled with additional crushed rock. For evaluation of the concrete slab-on-grade floors using the beam on elastic foundation method, a modulus of subgrade reaction of 150 kcf (87 pci) should be assumed for the stiff, fine -grained soils anticipated to be present at foundation subgrade elevation following adequate site preparation as described above. This value assumes the concrete slab system is designed and constructed as recommended herein, with a minimum thickness of 8 inches of 1½”-0 crushed aggregate beneath the slab. The total thickness of crushed aggregate will be dependent on the subgrade conditions at the time of construction and should be verified visually by proof-rolling. Under-slab aggregate should be compacted to at least 95 percent of its maximum dry density as determined by ASTM D1557 (Modified Proctor) or equivalent. In areas where moisture will be detrimental to floor coverings or equipment inside the proposed structure, appropriate vapor barrier and damp-proofing measures should be implemented. A commonly applied vapor barrier system consists of a 10-mil polyethylene vapor barrier placed directly over the capillary break material. Other damp/vapor barrier systems may also be feasible. Appropriate design professionals should be consulted regarding vapor barrier and damp proofing systems, ventilation, building material selection and mold prevention issues, which are outside GeoPacific’s area of expertise. 7.10 Footing and Roof Drains Construction should include typical measures for controlling subsurface water beneat h the structures, including positive crawlspace drainage to an adequate low-point drain exiting the foundation, visqueen covering the exposed ground in the crawlspace, and crawlspace ventilation (foundation vents). The client should be informed and educated that some slow flowing water in the crawlspaces is considered normal and not necessarily detrimental to the structures given these other design elements incorporated into construction. Appropriate design professionals should be Preliminary Geotechnical Engineering Report Project No. 21-5865, Woodland Ridge Phases 3-8, Springfield, Oregon 21-5865, Woodland Ridge Phases 3-8 Geotechnical Report 21 Version 1.0, December 27, 2021 consulted regarding crawlspace ventilation, building material selection and mold prevention issues, which are outside GeoPacific’s area of expertise. Down spouts and roof drains should collect roof water in a system separate from the footing drains to reduce the potential for clogging. Roof drain water should be directed to an appropriate discharge point and storm system well away from structural foundations. Grades should be sloped downward and away from buildings to reduce the potential for ponded water near structures. Perimeter footing drains may be eliminated at the discretion of the geotechnical engineer based on soil conditions encountered at the site and experience with standard local construction practices . Where it is desired to reduce the potential for moist crawl spaces, footing drains may be installed. If concrete slab-on-grade floors are used, perimeter footing drains should be installed as recommended below. Where deemed necessary, perimeter footing drains should consist of 3 or 4-inch diameter, perforated plastic pipe embedded in a minimum of 1 ft3 per lineal foot of clean, free-draining drain rock. The drain-pipe and surrounding drain rock should be wrapped in non -woven geotextile (Mirafi 140N, or approved equivalent) to minimize the potential for clogging and/or ground loss due to piping. A minimum 0.5 percent fall should be maintained throughout the drain and non-perforated pipe outlet. Figure 5 presents a typical perimeter footing drain detail. In our opinion, footing drains may outlet at the curb, or on the back sides of lots where sufficient fall is not available to allow drainage to meet the street. 7.11 Permanent Below-Grade Walls Lateral earth pressures against below-grade retaining walls will depend upon the inclination of any adjacent slopes, type of backfill, degree of wall restraint, method of backfill placement, degree of backfill compaction, drainage provisions, and magnitude and location of any adjacent surcharge loads. At-rest soil pressure is exerted on a retaining wall when it is restrained against rotation. In contrast, active soil pressure will be exerted on a wall if its top is allowed to rotate or yield a distance of roughly 0.001 times its height or greater. If the subject retaining walls will be free to rotate at the top, they should be design ed for an active earth pressure equivalent to that generated by a fluid weighing 3 5 pcf for level backfill against the wall. For restrained wall, an at-rest equivalent fluid pressure of 52 pcf should be used in design, again assuming level backfill against the wall. These values assume that the recommended drainage provisions are incorporated, and hydrostatic pressures are not allowed to develop against the wall. During a seismic event, lateral earth pressures acting on below -grade structural walls will increase by an incremental amount that corresponds to the earthquake loading. Based on the Mononobe-Okabe equation and peak horizontal accelerations appropriate for the site location, seismic loading should be modeled using the active or at-rest earth pressures recommended above, plus an incremental rectangular-shaped seismic load of magnitude 6.5H, where H is the total height of the wall. We assume relatively level ground surface below the base of the walls . As such, we recommend a passive earth pressure of 320 pcf for use in design, assuming wall footings are cast against Preliminary Geotechnical Engineering Report Project No. 21-5865, Woodland Ridge Phases 3-8, Springfield, Oregon 21-5865, Woodland Ridge Phases 3-8 Geotechnical Report 22 Version 1.0, December 27, 2021 competent native soils or engineered fill. If the ground surface slopes down and away from the base of any of the walls, a lower passive earth pressure should be used and GeoPacific shou ld be contacted for additional recommendations. A coefficient of friction of 0.42 may be assumed along the interface between the base of the wall footing and subgrade soils. The recommended coefficient of friction and passive earth pressure values do not include a safety factor, and an appropriate safety factor should be included in de sign. The upper 12 inches of soil should be neglected in passive pressure computations unless it is protected by pavement or slabs on grade. The above recommendations for lateral earth pressures assume that the backfill behind the subsurface walls will consist of properly compacted structural fill, and no adjacent surcharge loading. If the walls will be subjected to the influence of surcharge loading within a horizontal distance equal to or less than the height of the wall, the walls should be designed for the additional horizontal pressure. For uniform surcharge pressures, a uniformly distributed lateral pressure of 0.3 times the surcharge pressure should be added. Traffic surcharges may be estimated using an additional vertical load of 250 psf (2 feet of additional fill), in accordance with local practice. The recommended equivalent fluid densities assume a free -draining condition behind the walls so that hydrostatic pressures do not build-up. This can be accomplished by placing a 12 to 18-inch wide zone of sand and gravel containing less than 5 percent passing the No. 200 sieve against the walls. A 3-inch minimum diameter perforated, plastic drain-pipe should be installed at the base of the walls and connected to a suitable discharge point to remove water in this zone of sand and gravel . The drain-pipe should be wrapped in filter fabric (Mirafi 140N or other as approved by the geotechnical engineer) to minimize clogging. Wall drains are recommended to prevent detrimental effects of surface water runoff on foundations – not to dewater groundwater. Drains should not be expected to eliminate all potential sources of water entering a basement or beneath a slab-on-grade. An adequate grade to a low point outlet drain in the crawlspace is required by code. Underslab drains are sometimes added beneath the slab when placed over soils of low permeability and shallow, perched groundwater. Water collected from the wall drains should be directed into the local storm drain system or other suitable outlet. A minimum 0.5 percent fall should be maintained throughout the drai n and non-perforated pipe outlet. Down spouts and roof drains should not be connected to the wall drains in order to reduce the potential for clogging. The drains should include clean-outs to allow periodic maintenance and inspection. Grades around the proposed structure should be sloped such that surface water drains away from the building. GeoPacific should be contacted during construction to verify subgrade strength in wall keyway excavations, to verify that backslope soils are in accordance with our a ssumptions, and to take density tests on the wall backfill materials. Structures should be located a horizontal distance of at least 1.5H away from the back of the retaining wall, where H is the total height of the wall. GeoPacific should be contacted for additional foundation recommendations where structures are located closer than 1.5H to the top of any wall. Preliminary Geotechnical Engineering Report Project No. 21-5865, Woodland Ridge Phases 3-8, Springfield, Oregon 21-5865, Woodland Ridge Phases 3-8 Geotechnical Report 23 Version 1.0, December 27, 2021 8.0 SEISMIC DESIGN The Oregon Department of Geology and Mineral Industries (DOGAMI), Oregon HazVu: 2021 Statewide GeoHazards Viewer indicates that the site is in an area where strong ground shaking is anticipated during an earthquake. Structures should be designed to resist earthquake loading in accordance with the methodology described in the 2018 International Building Code (IBC) with applicable Oregon Structural Specialty Code (OSSC) revisions (current 2019). We recommend Site Class D be used for design as defined in ASCE 7-16, Chapter 20, and Table 20.3-1. Design values determined for the site using the ATC Hazards by Location 2021 Seismic Design Maps Summary Report are summarized in Table 7 and are based upon observed existing soil conditions. Table 7: Recommended Earthquake Ground Motion Parameters (ASCE 2016) Parameter Value Location (Lat, Long), degrees 44.037, -122.938 Probabilistic Ground Motion Values, 2% Probability of Exceedance in 50 yrs Peak Ground Acceleration PGAM 0.392 g Short Period, Ss 0.637 g 1.0 Sec Period, S1 0.369 g Soil Factors for Site Class C: Fa 1.29 * Fv 1.931 SDs = 2/3 x Fa x Ss 0.548 g *SD1 = 2/3 x Fv x S1 0.475 g Seismic Design Category D * Fv value reported in the above table is a straight-line interpolation of mapped spectral response acceleration at 1-second period, S1 per Table 1613.2.3(2) with the assumption that Exception 2 of ASCE 7-16 Chapter 11.4.8 is met per the Structural Engineer. If Exception 2 is not met, and the long-period site coefficient (Fv) is required for design, GeoPacific Engineering can be consulted to provide a site-specific procedure as per ASCE 7-16, Chapter 21. 8.1 Soil Liquefaction The Oregon Department of Geology and Mineral Industries (DOGAMI), Oregon HazVu: 202 1 Statewide GeoHazards Viewer indicates that the site is in an area considered to be at low risk for soil liquefaction during an earthquake. Soil liquefaction is a phenomenon wherein saturated soil deposits temporarily lose strength and behave as a liquid in response to ground shaking caused by strong earthquakes. Soil liquefaction is generally limited to loose sands and granular soils located below the water table, and fine-grained soils with a plasticity index less than 15. The upper 51.5 feet of the site was observed to be underlain by medium dense to dense, very stiff to hard, interlayered clays, silts, clayey gravels, and gravelly clay displaying low to high plasticity. Static groundwater was only encountered in test pit TP-17. Based on our review of available well logs from the vicinity of the subject site we expect that static ground water may be encountered at depths ranging from approximately 50 to 75 feet bgs, depending on ground surface elevation. Based upon the results of our study, it is our opinion that the risk of soil liquefaction and lateral spreading at the site during a seismic event at the subject site should be considered to be low. Preliminary Geotechnical Engineering Report Project No. 21-5865, Woodland Ridge Phases 3-8, Springfield, Oregon 21-5865, Woodland Ridge Phases 3-8 Geotechnical Report 24 Version 1.0, December 27, 2021 9.0 UNCERTAINTIES AND LIMITATIONS We have prepared this report for the owner and their consultants for use in design of this project only. This report should be provided in its entirety to prospective contractors for bidding and estimating purposes; however, the conclusions and interpretations presented in this report should not be construed as a warranty of the subsurface conditions. Experience has shown that soil and groundwater conditions can vary significantly over small distances. Inconsistent conditions can occur between explorations that may not be detected by a geotechnical study. If, during future site operations, subsurface conditions are encountered which vary appreciab ly from those described herein, GeoPacific should be notified for review of the recommendations of this report, and revision of such if necessary. Sufficient geotechnical monitoring, testing and consultation should be provided during construction to confirm that the conditions encountered are consistent with those indicated by explorations. The checklist attached to this report outlines recommended geotechnical observations and testing for the project. Recommendations for design changes will be provided should conditions revealed during construction differ from those anticipated, and to verify that the geotechnical aspects of construction comply with the contract plans and specifications. Within the limitations of scope, schedule and budget, GeoPacific attempted to execute these services in accordance with generally accepted professional principles and practices in the fields of geotechnical engineering and engineering geology at the time the report was prepared. No warranty, expressed or implied, is made. The scope of our work did not include environmental assessments or evaluations regarding the presence or absence of wetlands or hazardous or toxic substances in the soil, surface water, or groundwater at this site. We appreciate this opportunity to be of service. Sincerely, GEOPACIFIC ENGINEERING, INC. Benjamin L. Cook, C.E.G. James D. Imbrie, P.E., G. E. Associate Engineering Geologist Principal Geotechnical Engineer Preliminary Geotechnical Engineering Report Project No. 21-5865, Woodland Ridge Phases 3-8, Springfield, Oregon 21-5865, Woodland Ridge Phases 3-8 Geotechnical Report 25 Version 1.0, December 27, 2021 REFERENCES ATC Hazards by Location, (https://hazards.atcouncil.org). Atwater, B.F., 1992, Geologic evidence for earthquakes during the past 2,000 years along the Copalis River, southern coastal Washington: Journal of Geophysical Research, v. 97, p. 1901-1919. Carver, G.A., 1992, Late Cenozoic tectonics of coastal northern California: American Association of Petroleum Geologists-SEPM Field Trip Guidebook, 1992. Gannet, Marshall W., and Caldwell, Rodney R., Generalized Geologic Map of the Willamette Lowland, U.S. Department of the interior, U.S. Geological Survey, 1998. Goldfinger, C., Kulm, L.D., Yeats, R.S., Appelgate, B, MacKay, M.E., and Cochrane, G.R., 1996, Active strike-slip faulting and folding of the Cascadia Subduction-Zone plate boundary and forearc in central and northern Oregon: in Assessing earthquake hazards and reducing risk in the Pacific Northwest, v. 1: U.S. Geological Survey Professional Paper 1560, P. 223-256. Ma, L., Madin, I.P., Duplantis, S., and Williams, K.J., 2012, Lidar-based Surficial Geologic Map and Database of the Greater Portland, Oregon, Area, Clackamas, Columbia, Marion, Multnomah, Washington, and Yamhill Counties, Oregon, and Clark County, Washington, DOGAMI Open-File Report O-12-02 Mabey, M.A., Madin, I.P., and Black G.L., 1996, Relative Earthquake Hazard Map of the Lake Oswego Quadrangle, Clackamas, Multnomah and Washington Counties, Oregon: Oregon Department of Geology and Mineral Industries Madin, I.P., 1990, Earthquake hazard geology maps of the Portland metropolitan area, Oregon: Oregon Department of Geology and Mineral Industries Open-File Report 0-90-2, scale 1:24,000, 22 p. Oregon Department of Geology and Mineral Industries, Statewide Geohazards Viewer, www.oregongeology.org/hazvu. Peterson, C.D., Darioenzo, M.E., Burns, S.F., and Burris, W.K., 1993, Field trip guide to Cascadia paleoseismic evidence along the northern California coast: evidence of subduction zone seismicity in the central Cascadia margin: Oregon Geology, v. 55, p. 99-144. The Preliminary Geologic Map of the Springfield Quadrangle, Lane County, Oregon (Oregon Department of Geology and Mineral Industries, Open-File Report 0-06-07, Hladky, F.R. and McCaslin, G.R., 2006). United States Geological Survey, USGS Earthquake Hazards Program Website (earthquake.usgs.gov). Unruh, J.R., Wong, I.G., Bott, J.D., Silva, W.J., and Lettis, W.R., 1994, Seismotectonic evaluation: Scoggins Dam, Tualatin Project, Northwest Oregon: unpublished report by William Lettis and Associates and Woodward Clyde Federal Services, Oakland, CA, for U. S. Bureau of Reclamation, Denver CO (in Geomatrix Consultants, 1995). Web Soil Survey, Natural Resources Conservation Service, United States Department of Agriculture 2015 website. (http://websoilsurvey.nrcs.usda.gov/app/HomePage.htm.). Werner, K.S., Nabelek, J., Yeats, R.S., Malone, S., 1992, The Mount Angel fault: implications of seismic-reflection data and the Woodburn, Oregon, earthquake sequence of August, 1990: Oregon Geology, v. 54, p. 112-117. Wong, I. Silva, W., Bott, J., Wright, D., Thomas, P., Gregor, N., Li., S., Mabey, M., Sojourner, A., and Wang, Y., 2000, Earthquake Scenario and Probabilistic Ground Shaking Maps for the Portland, Oregon, Metropolitan Area; State of Oregon Department of Geology and Mineral Industries; Interpretative Map Series IMS-16 Yeats, R.S., Graven, E.P., Werner, K.S., Goldfinger, C., and Popowski, T., 1996, Tectonics of the Willamette Valley, Oregon: in Assessing earthquake hazards and reducing risk in the Pacific Northwest, v. 1: U.S. Geological Survey Professional Paper 1560, P. 183-222, 5 plates, scale 1:100,000. Yelin, T.S., 1992, An earthquake swarm in the north Portland Hills (Oregon): More speculations on the seismotectonics of the Portland Basin: Geological Society of America, Programs with Abstracts, v. 24, no. 5, p. 92. Preliminary Geotechnical Engineering Report Project No. 21-5865, Woodland Ridge Phases 3-8, Springfield, Oregon 21-5865, Woodland Ridge Phases 3-8 Geotechnical Report 26 Version 1.0, December 27, 2021 CHECKLIST OF RECOMMENDED GEOTECHNICAL TESTING AND OBSERVATION Item No. Procedure Timing By Whom Done 1 Preconstruction meeting Prior to beginning site work Contractor, Developer, Civil and Geotechnical Engineers 2 Fill removal from site or sorting and stockpiling Prior to mass stripping Soil Technician/ Geotechnical Engineer 3 Stripping, aeration, and root- picking operations During stripping Soil Technician 4 Compaction testing of engineered fill (95% of Standard Proctor) During filling, tested every 2 vertical feet Soil Technician 5 Foundation Subgrade Compaction (95% of Modified Proctor) During Foundation Preparation, Prior to Placement of Reinforcing Steel Soil Technician/ Geotechnical Engineer 6 Compaction testing of trench backfill (95% of Modified Proctor) During backfilling, tested every 4 vertical feet for every 200 linear feet Soil Technician 7 Street Subgrade Inspection (95% of Standard Proctor) Prior to placing base course Soil Technician 8 Base course compaction (95% of Modified Proctor) Prior to paving, tested every 200 linear feet Soil Technician 9 Asphalt Compaction (92% Rice Value) During paving, tested every 100 linear feet Soil Technician 10 Final Geotechnical Engineer’s Report Completion of project Geotechnical Engineer Real-World Geotechnical Solutions Investigation • Design • Construction Support 14835 SW 72nd Avenue Tel (503) 598-8445 Portland, Oregon 97224 Fax (503) 941-9281 FIGURES Real-World Geotechnical Solutions Investigation • Design • Construction Support 14835 SW 72nd Avenue Tel (503) 598-8445 Portland, Oregon 97224 Fax (503) 941-9281 EXPLORATION LOGS Real-World Geotechnical Solutions Investigation • Design • Construction Support 14835 SW 72nd Avenue Tel (503) 598-8445 Portland, Oregon 97224 Fax (503) 941-9281 LABORATORY TEST RESULTS UNIFIED SOIL CLASSIFICATION SYSTEM UNIFIED SOIL CLASSIFICATION AND SYMBOL CHART COARSE-GRAINED SOILS (more than 50% of material is larger than No. 200 sieve size.) GRAVELS More than 50% of coarse fraction larger than No. 4 sieve size SANDS 50% or more of coarse fraction smaller than No. 4 sieve size Clean Gravels (Less than 5% fines) GW GP Well-graded gravels, gravel-sand mixtures, little or no fines Poorly-graded gravels, gravel-sand mixtures, little or no fines Gravels with fines (More than 12% fines) GM GC Silty gravels, gravel-sand-silt mixtures Clayey gravels, gravel-sand-clay mixtures Clean Sands (Less than 5% fines) SW SP Well-graded sands, gravelly sands, little or no fines Poorly graded sands, gravelly sands, little or no fines Sands with fines More than 12% fines SM Silty sands, sand-silt mixtures SC Clayey sands, sand-clay mixtures FINE-GRAINED SOILS (50% or more of material is smaller than No. 200 sieve size.) SILTS AND CLAYS Liquid limit less than 50% SILTS AND CLAYS Liquid limit 50% or greater HIGHLY ORGANIC SOILS ML CL OL MH CH OH PT Inorganic silts and very fine sands, rock flour, silty of clayey fine sands or clayey silts with slight plasticity Inorganic clays of low to medium plasticity, gravelly clays, sandy clays, silty clays, lean clays Organic silts and organic silty clays of low plasticity Inorganic silts, micaceous or diatomaceous fine sandy or silty soils, elastic silts Inorganic clays of high plasticity, fat clays Organic clays of medium to high plasticity, organic silts Peat and other highly organic soils GW GP GM GC SW SP SM SC LABORATORY CLASSIFICATION CRITERIA cu D 50 D 30 = --greater than 4; Cc = between 1 and 3 D 10 010 x D50 Not meeting all gradation requirements for GW Atterberg limits below "A" Above "A" line with P.I. between line or P.I. less than 4 4 and 7 are borderline cases Atterberg limits above "A" requiring use of dual symbols line with P. I. greater than 7 cu D 50 D 30 = --greater than 4; Cc = between 1 and 3 D 10 01o xD60 Not meeting all gradation requirements for GW Atterberg limits below "A" Limits plotting in shaded zone line or P.I. less than 4 with P.I. between 4 and 7 are Atterberg limits above "A" borderline cases requiring use line with P. I. greater than 7 of dual symbols. Determine percentages of sand and gravel from grain-size curve. Depending on percentage of fines (fraction smaller than No. 200 sieve size), coarse-grained soils are classified as follows: Less than 5 percent .................................... GW, GP, SW, SP More than 12 percent .................................. GM, GC, SM, SC 5 to 12 percent ................... Borderline cases requiring dual symbols PLASTICITY CHART 60 ,,/ � � 50 � CH / / >< 40 V" ALINE: Vp1 = on(LL-20) � 30 >-CL ,,/ MHloH 20 / j:: / 10 ...J CL+ML ./ ML&OL II.. 0 0 I 10 20 30 40 50 60 70 80 90 100 LIQUID LIMIT (LL) (%) SOIL DESCRIPTION AND CLASSIFICATION GUIDELINES Particle-Size Classification ASTM/USCS AASHTO COMPONENT size range sieve size range size range sieve size range Cobbles > 75 mm greater than 3 inches > 75 mm greater than 3 inches Gravel 75 mm – 4.75 mm 3 inches to No. 4 sieve 75 mm – 2.00 mm 3 inches to No. 10 sieve Coarse 75 mm – 19.0 mm 3 inches to 3/4-inch sieve - - Fine 19.0 mm – 4.75 mm 3/4-inch to No. 4 sieve - - Sand 4.75 mm – 0.075 mm No. 4 to No. 200 sieve 2.00 mm – 0.075 mm No. 10 to No. 200 sieve Coarse 4.75 mm – 2.00 mm No. 4 to No. 10 sieve 2.00 mm – 0.425 mm No. 10 to No. 40 sieve Medium 2.00 mm – 0.425 mm No. 10 to No. 40 sieve - - Fine 0.425 mm – 0.075 mm No. 40 to No. 200 sieve 0.425 mm – 0.075 mm No. 40 to No. 200 sieve Fines (Silt and Clay) < 0.075 mm Passing No. 200 sieve < 0.075 mm Passing No. 200 sieve Consistency for Cohesive Soil CONSISTENCY SPT N-VALUE (BLOWS PER FOOT) POCKET PENETROMETER (UNCONFINED COMPRESSIVE STRENGTH, tsf) Very Soft Soft Medium Stiff Stiff Very Stiff Hard Very Hard 2 2 to 4 4 to 8 8 to 15 15 to 30 30 to 60 greater than 60 less than 0.25 0.25 to 0.50 0.50 to 1.0 1.0 to 2.0 2.0 to 4.0 greater than 4.0 - Relative Density for Granular Soil RELATIVE DENSITY SPT N-VALUE (BLOWS PER FOOT) Very Loose Loose Medium Dense Dense Very Dense 0 to 4 4 to 10 10 to 30 30 to 50 more than 50 Moisture Designations TERM FIELD IDENTIFICATION Dry No moisture. Dusty or dry. Damp Some moisture. Cohesive soils are usually below plastic limit and are moldable. Moist Grains appear darkened, but no visible water is present. Cohesive soils will clump. Sand will bulk. Soils are often at or near plastic limit. Wet Visible water on larger grains. Sand and silt exhibit dilatancy. Cohesive soil can be readily remolded. Soil leaves wetness on the hand when squeezed. Soil is much wetter than optimum moisture content and is above plastic limit. AASHTO SOIL CLASSIFICATION SYSTEM TABLE 1. Classification of Soils and Soil-Aggregate Mixtures Granular Materials Silt-Clay Materials General Classification (35 Percent or Less Passing .075 mm) (More than 35 Percent Passing 0.075) Group Classification A-1 A-3 A-2 A-4 A-5 A-6 A-7 Sieve analysis, percent passing: 2.00 mm (No. 10) - - - 0.425 mm (No. 40) 50 max 51 min - - - - - 0.075 mm (No. 200) 25 max 10 max 35 max 36 min 36 min 36 min 36 min Characteristics of fraction passing 0.425 mm (No. 40) Liquid limit 40 max 41 min 40 max 41 min Plasticity index 6 max N.P. 10 max 10 max 11 min 11 min General rating as subgrade Excellent to good Fair to poor Note: The placing of A-3 before A-2 is necessary in the "left to right elimination process" and does not indicate superiority of A-3 over A-2. TABLE 2. Classification of Soils and Soil-Aggregate Mixtures Granular Materials Silt-Clay Materials General Classification (35 Percent or Less Passing 0.075 mm) (More than 35 Percent Passing 0.075 mm) A-1 A-2 A-7 A-7-5, Group Classification A-1-a A-1-b A-3 A-2-4 A-2-5 A-2-6 A-2-7 A-4 A-5 A-6 A-7-6 Sieve analysis, percent passing: 2.00 mm (No. 10) 50 max - - - - - - - - - - 0.425 mm (No. 40) 30 max 50 max 51 min - - - - - - - - 0.075 mm (No. 200) 15 max 25 max 10 max 35 max 35 max 35 max 35 max 36 min 36 min 36 min 36 min Characteristics of fraction passing 0.425 mm (No. 40) Liquid limit 40 max 41 min 40 max 41 min 40 max 41 min 40 max 41 min Plasticity index 6 max N.P. 10 max 10 max 11 min 11 min 10 max 10 max 11 min 11min Usual types of significant constituent materials Stone fragments, Fine gravel and sand sand Silty or clayey gravel and sand Silty soils Clayey soils General ratings as subgrade Excellent to Good Fair to poor Note: Plasticity index of A-7-5 subgroup is equal to or less than LL minus 30. Plasticity index of A-7-6 subgroup is greater than LL minus 30 (see Figure 2). AASHTO = American Association of State Highway and Transportation Officials GROUP SYMBOL GROUP NAME <5% fines Cu≥4 and 1≤Cc≤3 GW <15% sand Well-graded gravel ≥15% sand Well-graded gravel with sand Cu<4 and/or 1>Cc>3 GP <15% sand Poorly graded gravel ≥15% sand Poorly graded gravel with sand fines = ML or MH GW-GM <15% sand Well-graded gravel with silt Cu≥4 and 1≤Cc≤3 ≥15% sand Well-graded gravel with silt and sand fines = CL, CH,GW-GC <15% sand Well-graded gravel with clay (or silty clay) GRAVEL (or CL-ML)≥15% sand Well-graded gravel with clay and sand % gravel >5-12% fines (or silty clay and sand) % sand fines = ML or MH GP-GM <15% sand Poorly graded gravel with silt Cu<4 and/or 1>Cc>3 ≥15% sand Poorly graded gravel with silt and sand fines = CL, CH,GP-GC <15% sand Poorly graded gravel with clay (or silty clay) (or CL-ML)≥15% sand Poorly graded gravel with clay and sand (or silty clay and sand) fines = ML or MH GM <15% sand Silty gravel ≥15% sand Silty gravel with sand >12% fines fines = CL or CH GC <15% sand Clayey gravel ≥15% sand Clayey gravel with sand fines = CL-ML GC-GM <15% sand Silty, clayey gravel ≥15% sand Silty, clayey gravel with sand <5% fines Cu≥6 and 1≤Cc≤3 SW <15% gravel Well-graded sand ≥15% gravel Well-graded sand with gravel Cu<6 and/or 1>Cc>3 SP <15% gravel Poorly graded sand ≥15% gravel Poorly graded sand with gravel fines = ML or MH SW-SM <15% gravel Well-graded sand with silt Cu≥6 and 1≤Cc≤3 ≥15% gravel Well-graded sand with silt and gravel fines = CL, CH,SW-SC <15% gravel Well-graded sand with clay (or silty clay) SAND (or CL-ML)≥15% gravel Well-graded sand with clay and gravel % sand ≥5-12% fines (or silty clay and gravel) % gravel fines = ML or MH SP-SM <15% gravel Poorly graded sand with silt Cu<6 and/or 1>Cc>3 ≥15% gravel Poorly graded sand with silt and gravel fines = CL, CH,SP-SC <15% gravel Poorly graded sand with clay (or silty clay) (or CL-ML)≥15% gravel Poorly graded sand with clay and gravel (or silty clay and gravel) fines = ML or MH SM <15% gravel Silty sand ≥15% gravel Silty sand with gravel >12% fines fines = CL or CH SC <15% gravel Clayey sand ≥15% gravel Clayey sand with gravel fines = CL-ML SC-SM <15% gravel Silty, clayey sand ≥15% gravel Silty, clayey sand with gravel GROUP SYMBOL GROUP NAME < 30% plus No. 200 < 15% plus No. 200 Lean clay 15-29% plus No. 200 % sand ≥ % gravel Lean clay with sand Pl > 7 and plots CL % sand < % gravel Lean clay with gravel on or above % sand ≥ % gravel < 15% gravel Sandy lean clay "A"-line ≥ 30% plus No. 200 ≥ 15% gravel Sandy lean clay with gravel % sand < % gravel < 15% sand Gravelly lean clay ≥ 15% sand Gravelly lean clay with sand < 30% plus No. 200 < 15% plus No. 200 Silty clay 15-29% plus No. 200 % sand ≥ % gravel Silty clay with sand 4 ≤ Pl ≤ 7 and CL-ML % sand < % gravel Silty clay with gravel Inorganic plots on or above % sand ≥ % gravel < 15% gravel Sandy silty clay "A"-line ≥ 30% plus No. 200 ≥ 15% gravel Sandy silty clay with gravel % sand < % gravel < 15% sand Gravelly silty clay ≥ 15% sand Gravelly silty clay with sand < 30% plus No. 200 < 15% plus No. 200 Silt LL < 50 15-29% plus No. 200 % sand ≥ % gravel Silt with sand Pl < 4 or plots ML % sand < % gravel Silt with gravel below "A"-line % sand ≥ % gravel < 15% gravel Sandy silt ≥ 30% plus No. 200 ≥ 15% gravel Sandy silt with gravel % sand < % gravel < 15% sand Gravelly silt LL -ovendried ≥ 15% sand Gravelly silt with sand Organic -------------------- < 0.75 OL LL -not dried < 30% plus No. 200 < 15% plus No. 200 Fat clay 15-29% plus No. 200 % sand ≥ % gravel Fat clay with sand Pl plots on or CH % sand < % gravel Fat clay with gravel above "A"-line % sand ≥ % gravel < 15% gravel Sandy fat clay ≥ 30% plus No. 200 ≥ 15% gravel Sandy fat clay with gravel % sand < % gravel < 15% sand Gravelly fat clay Inorganic ≥ 15% sand Gravelly fat clay with sand < 30% plus No. 200 < 15% plus No. 200 Elastic silt 15-29% plus No. 200 % sand ≥ % gravel Elastic silt with sand LL ≥ 50 Pl plots below MH % sand < % gravel Elastic silt with gravel "A"-line % sand ≥ % gravel < 15% gravel Sandy elastic silt ≥ 30% plus No. 200 ≥ 15% gravel Sandy elastic silt with gravel LL -ovendried % sand < % gravel < 15% sand Gravelly elastic silt Organic -------------------- < 0.75 OH ≥ 15% sand Gravelly elastic silt with sand LL -not dried Flow Chart for Classifying Coarse-Grained Soils (More Than 50% Retained on No. 200 Sieve) Flow Chart for Classifying Fine-Grained Soil (50% or More Passes No. 200 Sieve) Particle Size Distribution Report PERCENT FINER0 10 20 30 40 50 60 70 80 90 100 PERCENT COARSER100 90 80 70 60 50 40 30 20 10 0 GRAIN SIZE - mm. 0.0010.010.1110100 % +3"Coarse % Gravel Fine Coarse Medium % Sand Fine Silt % Fines Clay 0.0 0.0 0.5 1.0 15.5 19.5 63.56 in.3 in.2 in.1½ in.1 in.¾ in.½ in.3/8 in.#4#10#20#30#40#60#100#140#200TEST RESULTS Opening Percent Spec. *Pass? Size Finer (Percent) (X=Fail) Material Description Atterberg Limits (ASTM D 4318) Classification Coefficients Date Received:Date Tested: Tested By: Checked By: Title: Date Sampled:Location: B-2Sample Number: S21-239 Depth: 10' Client: Project: Project No:Figure Sandy Elastic Silt .75 .5 .375 .25 #4 #10 #20 #40 #100 #200 100.0 100.0 100.0 100.0 99.5 98.5 95.5 83.0 69.4 63.5 48.1 53.2 5.1 MH A-5(5) 0.6081 0.4728 Moisture 54.9% 9/21/2021 SJC 9/13/2021 A & O Engineering LLC Woodland Ridge Phases 3-8 21-5865 PL=LL=PI= USCS (D 2487)=AASHTO (M 145)= D90=D85=D60=D50=D30=D15=D10=Cu=Cc= Remarks *(no specification provided) GEOPACIFIC ENGINEERING, INC. Tested By: SJC LIQUID AND PLASTIC LIMITS TEST REPORT PLASTICITY INDEX0 10 20 30 40 50 60 LIQUID LIMIT 0 10 20 30 40 50 60 70 80 90 100 110 CL-ML CL or O L CH or O H ML or OL MH or OH Dashed line indicates the approximate upper limit boundary for natural soils 47 WATER CONTENT49 50 51 52 53 54 55 56 57 58 59 NUMBER OF BLOWS 5 6 7 8 9 10 20 25 30 40 MATERIAL DESCRIPTION LL PL PI %<#40 %<#200 USCS Project No.Client:Remarks: Project: Location: B-2Sample Number: S21-239 Depth: 10' GEOPACIFIC ENGINEERING, INC.Figure Sandy Elastic Silt 53.2 48.1 5.1 83.0 63.5 MH 21-5865 A & O Engineering LLC Woodland Ridge Phases 3-8 Particle Size Distribution Report PERCENT FINER0 10 20 30 40 50 60 70 80 90 100 PERCENT COARSER100 90 80 70 60 50 40 30 20 10 0 GRAIN SIZE - mm. 0.0010.010.1110100 % +3"Coarse % Gravel Fine Coarse Medium % Sand Fine Silt % Fines Clay 0.0 0.0 8.3 6.6 15.9 19.5 49.76 in.3 in.2 in.1½ in.1 in.¾ in.½ in.3/8 in.#4#10#20#30#40#60#100#140#200TEST RESULTS Opening Percent Spec. *Pass? Size Finer (Percent) (X=Fail) Material Description Atterberg Limits (ASTM D 4318) Classification Coefficients Date Received:Date Tested: Tested By: Checked By: Title: Date Sampled:Location: B-2Sample Number: S21-240 Depth: 20' Client: Project: Project No:Figure Silty Sand .75 .5 .375 .25 #4 #10 #20 #40 #100 #200 100.0 98.1 97.3 94.5 91.7 85.1 77.7 69.2 57.0 49.7 42.8 45.3 2.5 SM A-5(1) 3.9090 1.9634 0.1961 0.0771 Moisture 48.2% 9/21/2021 SJC+ 9/13/2021 A & O Engineering LLC Woodland Ridge Phases 3-8 21-5865 PL=LL=PI= USCS (D 2487)=AASHTO (M 145)= D90=D85=D60=D50=D30=D15=D10=Cu=Cc= Remarks *(no specification provided) GEOPACIFIC ENGINEERING, INC. Tested By: SJC LIQUID AND PLASTIC LIMITS TEST REPORT PLASTICITY INDEX0 10 20 30 40 50 60 LIQUID LIMIT 0 10 20 30 40 50 60 70 80 90 100 110 CL-ML CL or O L CH or O H ML or OL MH or OH Dashed line indicates the approximate upper limit boundary for natural soils 47 WATER CONTENT43.8 44.2 44.6 45 45.4 45.8 46.2 46.6 47 47.4 47.8 NUMBER OF BLOWS 5 6 7 8 9 10 20 25 30 40 MATERIAL DESCRIPTION LL PL PI %<#40 %<#200 USCS Project No.Client:Remarks: Project: Location: B-2Sample Number: S21-240 Depth: 20' GEOPACIFIC ENGINEERING, INC.Figure Silty Sand 45.3 42.8 2.5 69.2 49.7 SM 21-5865 A & O Engineering LLC Woodland Ridge Phases 3-8 Particle Size Distribution Report PERCENT FINER0 10 20 30 40 50 60 70 80 90 100 PERCENT COARSER100 90 80 70 60 50 40 30 20 10 0 GRAIN SIZE - mm. 0.0010.010.1110100 % +3"Coarse % Gravel Fine Coarse Medium % Sand Fine Silt % Fines Clay 0.0 0.0 0.0 0.0 0.7 2.1 97.26 in.3 in.2 in.1½ in.1 in.¾ in.½ in.3/8 in.#4#10#20#30#40#60#100#140#200TEST RESULTS Opening Percent Spec. *Pass? Size Finer (Percent) (X=Fail) Material Description Atterberg Limits (ASTM D 4318) Classification Coefficients Date Received:Date Tested: Tested By: Checked By: Title: Date Sampled:Location: B-2Sample Number: S21-241 Depth: 30' Client: Project: Project No:Figure Elastic Silt .75 .5 .375 .25 #4 #10 #20 #40 #100 #200 100.0 100.0 100.0 100.0 100.0 100.0 99.8 99.3 98.2 97.2 49.4 70.7 21.3 MH A-7-5(32) Moisture 74.6% 9/21/2021 SJC 9/13/2021 A & O Engineering LLC Woodland Ridge Phases 3-8 21-5865 PL=LL=PI= USCS (D 2487)=AASHTO (M 145)= D90=D85=D60=D50=D30=D15=D10=Cu=Cc= Remarks *(no specification provided) GEOPACIFIC ENGINEERING, INC. Tested By: SJC LIQUID AND PLASTIC LIMITS TEST REPORT PLASTICITY INDEX0 10 20 30 40 50 60 LIQUID LIMIT 0 10 20 30 40 50 60 70 80 90 100 110 CL-ML CL or O L CH or O H ML or OL MH or OH Dashed line indicates the approximate upper limit boundary for natural soils 47 WATER CONTENT66 67 68 69 70 71 72 73 74 75 76 NUMBER OF BLOWS 5 6 7 8 9 10 20 25 30 40 MATERIAL DESCRIPTION LL PL PI %<#40 %<#200 USCS Project No.Client:Remarks: Project: Location: B-2Sample Number: S21-241 Depth: 30' GEOPACIFIC ENGINEERING, INC.Figure Elastic Silt 70.7 49.4 21.3 99.3 97.2 MH 21-5865 A & O Engineering LLC Woodland Ridge Phases 3-8 Particle Size Distribution Report PERCENT FINER0 10 20 30 40 50 60 70 80 90 100 PERCENT COARSER100 90 80 70 60 50 40 30 20 10 0 GRAIN SIZE - mm. 0.0010.010.1110100 % +3"Coarse % Gravel Fine Coarse Medium % Sand Fine Silt % Fines Clay 0.0 10.5 16.5 6.2 11.8 15.0 40.06 in.3 in.2 in.1½ in.1 in.¾ in.½ in.3/8 in.#4#10#20#30#40#60#100#140#200TEST RESULTS Opening Percent Spec. *Pass? Size Finer (Percent) (X=Fail) Material Description Atterberg Limits (ASTM D 4318) Classification Coefficients Date Received:Date Tested: Tested By: Checked By: Title: Date Sampled:Location: B-2Sample Number: S21-242 Depth: 40' Client: Project: Project No:Figure Silty Sand with Gravel 3 1.5 1 .75 .5 .375 .25 #4 #10 #20 #40 #100 #200 100.0 100.0 93.8 89.5 81.7 79.6 75.2 73.0 66.8 61.0 55.0 45.6 40.0 NP NV NP SM A-4(0) 19.5826 15.3162 0.7495 0.2457 Moisture 31.0% 9/21/2021 SJC 9/13/2021 A & O Engineering LLC Woodland Ridge Phases 3-8 21-5865 PL=LL=PI= USCS (D 2487)=AASHTO (M 145)= D90=D85=D60=D50=D30=D15=D10=Cu=Cc= Remarks *(no specification provided) GEOPACIFIC ENGINEERING, INC. Particle Size Distribution Report PERCENT FINER0 10 20 30 40 50 60 70 80 90 100 PERCENT COARSER100 90 80 70 60 50 40 30 20 10 0 GRAIN SIZE - mm. 0.0010.010.1110100 % +3"Coarse % Gravel Fine Coarse Medium % Sand Fine Silt % Fines Clay 0.0 0.0 16.0 9.0 13.2 16.1 45.76 in.3 in.2 in.1½ in.1 in.¾ in.½ in.3/8 in.#4#10#20#30#40#60#100#140#200TEST RESULTS Opening Percent Spec. *Pass? Size Finer (Percent) (X=Fail) Material Description Atterberg Limits (ASTM D 4318) Classification Coefficients Date Received:Date Tested: Tested By: Checked By: Title: Date Sampled:Location: B-2Sample Number: S21-243 Depth: 50' Client: Project: Project No:Figure Silty Sand with Gravel .75 .5 .375 .25 #4 #10 #20 #40 #100 #200 100.0 95.6 93.3 87.6 84.0 75.0 67.9 61.8 52.2 45.7 NP NV NP SM A-4(0) 7.4360 5.1888 0.3480 0.1189 Moisture 39.6% 9/21/2021 SJC 9/13/2021 A & O Engineering LLC Woodland Ridge Phases 3-8 21-5865 PL=LL=PI= USCS (D 2487)=AASHTO (M 145)= D90=D85=D60=D50=D30=D15=D10=Cu=Cc= Remarks *(no specification provided) GEOPACIFIC ENGINEERING, INC. Particle Size Distribution Report PERCENT FINER0 10 20 30 40 50 60 70 80 90 100 PERCENT COARSER100 90 80 70 60 50 40 30 20 10 0 GRAIN SIZE - mm. 0.0010.010.1110100 % +3"Coarse % Gravel Fine Coarse Medium % Sand Fine Silt % Fines Clay 0.0 0.0 0.0 0.3 1.3 3.9 94.56 in.3 in.2 in.1½ in.1 in.¾ in.½ in.3/8 in.#4#10#20#30#40#60#100#140#200TEST RESULTS Opening Percent Spec. *Pass? Size Finer (Percent) (X=Fail) Material Description Atterberg Limits (ASTM D 4318) Classification Coefficients Date Received:Date Tested: Tested By: Checked By: Title: Date Sampled:Location: TP-1Sample Number: S21-235 Depth: 4' Client: Project: Project No:Figure Fat Clay .75 .5 .375 .25 #4 #10 #20 #40 #100 #200 100.0 100.0 100.0 100.0 100.0 99.7 99.2 98.4 96.1 94.5 37.5 101.1 63.6 CH A-7-5(72) 9/9/2021 SJC 8/31/2021 A & O Engineering LLC Woodland Ridge Phases 3-8 21-5865 PL=LL=PI= USCS (D 2487)=AASHTO (M 145)= D90=D85=D60=D50=D30=D15=D10=Cu=Cc= Remarks *(no specification provided) GEOPACIFIC ENGINEERING, INC. Tested By: SJC LIQUID AND PLASTIC LIMITS TEST REPORT PLASTICITY INDEX0 20 40 60 80 100 120 LIQUID LIMIT 0 10 20 30 40 50 60 70 80 90 100 110 CL-ML CL or OL CH or OH ML or OL MH or OH Dashed line indicates the approximate upper limit boundary for natural soils 47 WATER CONTENT96 97 98 99 100 101 102 103 104 105 106 NUMBER OF BLOWS 5 6 7 8 9 10 20 25 30 40 MATERIAL DESCRIPTION LL PL PI %<#40 %<#200 USCS Project No.Client:Remarks: Project: Location: TP-1Sample Number: S21-235 Depth: 4' GEOPACIFIC ENGINEERING, INC.Figure Fat Clay 101.1 37.5 63.6 98.4 94.5 CH 21-5865 A & O Engineering LLC Woodland Ridge Phases 3-8 Project Name: Project #:21-5865 Sample ID:Depth:4' Material Type: Material Source: Sampled By:ABC Tested By:SJC Sample Date:8/31/2021 Tested Date:9/10/2021 Expansion Index, EI 143 16.9 89.8 52.0 0.2449 0.1016 Initial Dial Reading (0.001 in.) S21-235 Woodland Ridge Phases 3-8 Fat Clay TP-1 1.000 Potential Expansion 47.3 EXPANSION INDEX ASTM D4829 Final Moisture Content (0.1%) Expansion Index Final Dial Reading (0.001 in.) Initial Height (0.001 in.) Initial Moisture Content (0.1%) Initial Dry Unit Weight (0.1 lbf/cu.ft.) Initial Degree of Saturation (50.0+/-2%) 51-90 91-130 >130 Very Low Low Medium High Very High 0-20 21-50 Moisture Content from Trimmings Pan #15 Tare Wt. =272.3 Moist Wt. + Tare=388.8 Moisture=16.9 Dry Wt. + Tare=372 Expansion Ring 2 inch Radius x 1 inch Height=5.08 cm Radius x 2.54 cm Height Volume =205.9 cm^3 Ring Wt. (g) =368.2 Moist Density (g/cm^3) =1.7 Ring + Sample (g) =714.1 Dry Density (g/cm^3) =1.4 Dry Unit Wt. (lb/ft^3) =89.8 Degree of Saturation =52.0 Final Moisture =47.3 Ring + Sample after soaking (g) =778.7 Sample after soaking (g)410.5 Ring + Sample oven dry (g)=646.9 Sample oven dry (g)278.7 Expansion Index =143 Initial Dial Reading (0.001 in.) =0.2449 Final Dial Reading (0.001 in.) =0.1016 Particle Size Distribution Report PERCENT FINER0 10 20 30 40 50 60 70 80 90 100 PERCENT COARSER100 90 80 70 60 50 40 30 20 10 0 GRAIN SIZE - mm. 0.0010.010.1110100 % +3"Coarse % Gravel Fine Coarse Medium % Sand Fine Silt % Fines Clay 0.0 28.5 19.8 7.0 14.6 7.6 22.56 in.3 in.2 in.1½ in.1 in.¾ in.½ in.3/8 in.#4#10#20#30#40#60#100#140#200TEST RESULTS Opening Percent Spec. *Pass? Size Finer (Percent) (X=Fail) Material Description Atterberg Limits (ASTM D 4318) Classification Coefficients Date Received:Date Tested: Tested By: Checked By: Title: Date Sampled:Location: TP-3Sample Number: S21-232 Depth: 7' Client: Project: Project No:Figure Silty Gravel with Sand 3 1.5 1 .75 .5 .375 .25 #4 #10 #20 #40 #100 #200 100.0 79.0 73.0 71.5 62.5 59.6 54.7 51.7 44.7 35.6 30.1 25.3 22.5 32.1 51.1 19.0 GM A-2-7(1) 56.4421 47.9336 10.0177 3.8874 0.4158 Moisture 18.0% 9/2/2021 SJC 9/1/2021 BLC A & O Engineering LLC Woodland Ridge Phases 3-8 21-5865 PL=LL=PI= USCS (D 2487)=AASHTO (M 145)= D90=D85=D60=D50=D30=D15=D10=Cu=Cc= Remarks *(no specification provided) GEOPACIFIC ENGINEERING, INC. Tested By: SJC LIQUID AND PLASTIC LIMITS TEST REPORT PLASTICITY INDEX0 10 20 30 40 50 60 LIQUID LIMIT 0 10 20 30 40 50 60 70 80 90 100 110 CL-ML CL or O L CH or O H ML or OL MH or OH Dashed line indicates the approximate upper limit boundary for natural soils 47 WATER CONTENT49.8 50.2 50.6 51 51.4 51.8 52.2 52.6 53 53.4 53.8 NUMBER OF BLOWS 5 6 7 8 9 10 20 25 30 40 MATERIAL DESCRIPTION LL PL PI %<#40 %<#200 USCS Project No.Client:Remarks: Project: Location: TP-3Sample Number: S21-232 Depth: 7' GEOPACIFIC ENGINEERING, INC.Figure Silty Gravel with Sand 51.1 32.1 19.0 30.1 22.5 GM 21-5865 A & O Engineering LLC Woodland Ridge Phases 3-8 Particle Size Distribution Report PERCENT FINER0 10 20 30 40 50 60 70 80 90 100 PERCENT COARSER100 90 80 70 60 50 40 30 20 10 0 GRAIN SIZE - mm. 0.0010.010.1110100 % +3"Coarse % Gravel Fine Coarse Medium % Sand Fine Silt % Fines Clay 0.0 0.0 1.4 0.8 3.4 10.2 84.26 in.3 in.2 in.1½ in.1 in.¾ in.½ in.3/8 in.#4#10#20#30#40#60#100#140#200TEST RESULTS Opening Percent Spec. *Pass? Size Finer (Percent) (X=Fail) Material Description Atterberg Limits (ASTM D 4318) Classification Coefficients Date Received:Date Tested: Tested By: Checked By: Title: Date Sampled:Location: TP-11Sample Number: S21-233 Depth: 10' Client: Project: Project No:Figure Fat Clay with Sand .75 .5 .375 .25 #4 #10 #20 #40 #100 #200 100.0 100.0 99.1 98.8 98.6 97.8 96.3 94.4 89.6 84.2 37.3 89.0 51.7 CH A-7-5(51) 0.1592 0.0828 Moisture 40.8% 9/2/2021 SJC 9/1/2021 BLC A & O Engineering LLC Woodland Ridge Phases 3-8 21-5865 PL=LL=PI= USCS (D 2487)=AASHTO (M 145)= D90=D85=D60=D50=D30=D15=D10=Cu=Cc= Remarks *(no specification provided) GEOPACIFIC ENGINEERING, INC. Tested By: SJC LIQUID AND PLASTIC LIMITS TEST REPORT PLASTICITY INDEX0 10 20 30 40 50 60 LIQUID LIMIT 0 10 20 30 40 50 60 70 80 90 100 110 CL-ML CL or O L CH or O H ML or OL MH or OH Dashed line indicates the approximate upper limit boundary for natural soils 47 WATER CONTENT85 86 87 88 89 90 91 92 93 94 95 NUMBER OF BLOWS 5 6 7 8 9 10 20 25 30 40 MATERIAL DESCRIPTION LL PL PI %<#40 %<#200 USCS Project No.Client:Remarks: Project: Location: TP-11Sample Number: S21-233 Depth: 10' GEOPACIFIC ENGINEERING, INC.Figure Fat Clay with Sand 89.0 37.3 51.7 94.4 84.2 CH 21-5865 A & O Engineering LLC Woodland Ridge Phases 3-8 Particle Size Distribution Report PERCENT FINER0 10 20 30 40 50 60 70 80 90 100 PERCENT COARSER100 90 80 70 60 50 40 30 20 10 0 GRAIN SIZE - mm. 0.0010.010.1110100 % +3"Coarse % Gravel Fine Coarse Medium % Sand Fine Silt % Fines Clay 0.0 0.0 0.0 0.0 7.2 14.3 78.56 in.3 in.2 in.1½ in.1 in.¾ in.½ in.3/8 in.#4#10#20#30#40#60#100#140#200TEST RESULTS Opening Percent Spec. *Pass? Size Finer (Percent) (X=Fail) Material Description Atterberg Limits (ASTM D 4318) Classification Coefficients Date Received:Date Tested: Tested By: Checked By: Title: Date Sampled:Location: TP-16Sample Number: S21-234 Depth: 6' Client: Project: Project No:Figure Elastic Silt with Sand .75 .5 .375 .25 #4 #10 #20 #40 #100 #200 100.0 100.0 100.0 100.0 100.0 100.0 99.3 92.8 82.6 78.5 39.3 69.8 30.5 MH A-7-5(28) 0.3314 0.2012 Moisture 39.0% 9/2/2021 SJC 9/1/2021 BLC A & O Engineering LLC Woodland Ridge Phases 3-8 21-5865 PL=LL=PI= USCS (D 2487)=AASHTO (M 145)= D90=D85=D60=D50=D30=D15=D10=Cu=Cc= Remarks *(no specification provided) GEOPACIFIC ENGINEERING, INC. Tested By: SJC LIQUID AND PLASTIC LIMITS TEST REPORT PLASTICITY INDEX0 10 20 30 40 50 60 LIQUID LIMIT 0 10 20 30 40 50 60 70 80 90 100 110 CL-ML CL or O L CH or O H ML or OL MH or OH Dashed line indicates the approximate upper limit boundary for natural soils 47 WATER CONTENT65 66 67 68 69 70 71 72 73 74 75 NUMBER OF BLOWS 5 6 7 8 9 10 20 25 30 40 MATERIAL DESCRIPTION LL PL PI %<#40 %<#200 USCS Project No.Client:Remarks: Project: Location: TP-16Sample Number: S21-234 Depth: 6' GEOPACIFIC ENGINEERING, INC.Figure Elastic Silt with Sand 69.8 39.3 30.5 92.8 78.5 MH 21-5865 A & O Engineering LLC Woodland Ridge Phases 3-8 Real-World Geotechnical Solutions Investigation • Design • Construction Support 14835 SW 72nd Avenue Tel (503) 598-8445 Portland, Oregon 97224 Fax (503) 941-9281 SLOPE STABILITY CROSS-SECTIONS GP-GMGMCL1.5Distance0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310Elevation500510520530540550560570580590Elevation50051052053054055056057058059021-5865, Woodland Ridge Phases 3-8Geologic Cross-Section A to A'Existing Condition - Static AnalysisAA'GLACIER DRPLPLStatic Factor of Safety: 1.5With 30 Ft Slope SetbackColor Name Unit Weight (pcf)Cohesion'(psf)Phi' (°)CL 120 200 28GM 125 100 30GP-GM 125 25 3630 FEETFUTURE LOT, PHASE 7 GP-GMGMCL1.1Distance0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310Elevation500510520530540550560570580590Elevation50051052053054055056057058059021-5865, Woodland Ridge Phases 3-8Geologic Cross-Section A to A'Existing Condition - Seismic AnalysisPeak Ground Acceleration PGAm = 0.392g (1/2 PGAm = 0.196g)AA'GLACIER DRPLPLPseudostatic Factor of Safety: 1.1With 50 Ft Slope SetbackColor Name Unit Weight (pcf)Cohesion'(psf)Phi' (°)CL 120 200 28GM 125 100 30GP-GM 125 25 3650 FEETFUTURE LOT, PHASE 7 GP-GMGMCL1.8Distance0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310Elevation500510520530540550560570580590Elevation50051052053054055056057058059021-5865, Woodland Ridge Phases 3-8Geologic Cross-Section A to A'Post Construction - Static AnalysisAA'GLACIER DRPLPLStatic Factor of Safety: 1.8Proposed Grading and House Location = 50 Ft Slope SetbackColor Name Unit Weight (pcf)Cohesion'(psf)Phi' (°)CL 120 200 28GM 125 100 30GP-GM 125 25 3650 FEET FROM TOP OF SLOPE35 FEET FROM PROPERTY LINEFUTURE LOT, PHASE 7250 PSF SURCHARGE GP-GMGMCL1.1Distance0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310Elevation500510520530540550560570580590Elevation50051052053054055056057058059021-5865, Woodland Ridge Phases 3-8Geologic Cross-Section A to A'Post Construction - Seismic AnalysisPeak Ground Acceleration PGAm = 0.392g (1/2 PGAm = 0.196g)AA'GLACIER DRPLPLPseudostatoc Factor of Safety: 1.1Proposed Grading and House Location = 50 Ft Slope SetbackColor Name Unit Weight (pcf)Cohesion'(psf)Phi' (°)CL 120 200 28GM 125 100 30GP-GM 125 25 3650 FEET FROM TOP OF SLOPE35 FEET FROM PROPERTY LINEFUTURE LOT, PHASE 7250 PSF SURCHARGE GP-GMGMCL1.5Distance0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310 320Elevation500510520530540550560570580590Elevation50051052053054055056057058059021-5865, Woodland Ridge Phases 3-8Geologic Cross-Section B to B'Existing Condition - Static AnalysisBB'GLACIER RDLOT 25, PHASE 4PLPLStatic Factor of Safety: 1.5With 15 Ft Slope SetbackColor Name Unit Weight (pcf)Cohesion'(psf)Phi' (°)CL 120 200 28GM 125 100 30GP-GM 125 25 3615 FEET GP-GMGMCL1.1Distance0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310 320Elevation500510520530540550560570580590Elevation50051052053054055056057058059021-5865, Woodland Ridge Phases 3-8Geologic Cross-Section B to B'Existing Condition - Seismic AnalysisPeak Ground Acceleration PGAm = 0.392g (1/2 PGAm = 0.196g)BB'GLACIER RDLOT 25, PHASE 4PLPLPseudostatic Factor of Safety: 1.1With 25 Ft Slope SetbackColor Name Unit Weight (pcf)Cohesion'(psf)Phi' (°)CL 120 200 28GM 125 100 30GP-GM 125 25 3625 FEET GP-GMGMCL1.7Distance0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310 320Elevation500510520530540550560570580590Elevation50051052053054055056057058059021-5865, Woodland Ridge Phases 3-8Geologic Cross-Section B to B'Post Construction - Static AnalysisBB'GLACIER RDLOT 25, PHASE 4250 PSF SURCHARGEPLPLStatic Factor of Safety: 1.7Proposed Grading and House Location = 55 Ft Slope SetbackColor Name Unit Weight (pcf)Cohesion'(psf)Phi' (°)CL 120 200 28GM 125 100 30GP-GM 125 25 3655 FEET FROM TOP OF SLOPE15 FEET FROM PROPERTY LINE GP-GMGMCL1.2Distance0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310 320Elevation500510520530540550560570580590Elevation50051052053054055056057058059021-5865, Woodland Ridge Phases 3-8Geologic Cross-Section B to B'Post Construction - Seismic AnalysisPeak Ground Acceleration PGAm = 0.392g (1/2 PGAm = 0.196g)BB'GLACIER RDLOT 25, PHASE 4250 PSF SURCHARGEPLPLPseudostatic Factor of Safety: 1.2Proposed Grading and House Location = 55 Ft Slope SetbackColor Name Unit Weight (pcf)Cohesion'(psf)Phi' (°)CL 120 200 28GM 125 100 30GP-GM 125 25 3655 FEET FROM TOP OF SLOPE15 FEET FROM PROPERTY LINE GP-GMGMCL1.5Distance0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310 320Elevation500510520530540550560570580590Elevation50051052053054055056057058059021-5865, Woodland Ridge Phases 3-8Geologic Cross-Section C to C'Existing Condition - Static AnalysisCC'GLACIER RDLOT 20, PHASE 4PLPLStatic Factor of Safety: 1.5With 35 Ft Slope SetbackColor Name Unit Weight (pcf)Cohesion'(psf)Phi' (°)CL 120 200 28GM 125 100 30GP-GM 125 25 3635 FEET GP-GMGMCL1.1Distance0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310 320Elevation500510520530540550560570580590Elevation50051052053054055056057058059021-5865, Woodland Ridge Phases 3-8Geologic Cross-Section C to C'Existing Condition - Seismic AnalysisPeak Ground Acceleration PGAm = 0.392g (1/2 PGAm = 0.196g)CC'GLACIER RDLOT 20, PHASE 4PLPLPseudostatic Factor of Safety: 1.1With 35 Ft Slope SetbackColor Name Unit Weight (pcf)Cohesion'(psf)Phi' (°)CL 120 200 28GM 125 100 30GP-GM 125 25 3635 FEET GP-GMGMCL1.9Distance0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310 320Elevation500510520530540550560570580590Elevation50051052053054055056057058059021-5865, Woodland Ridge Phases 3-8Geologic Cross-Section C to C'Post Construction - Static AnalysisCC'GLACIER RDLOT 20, PHASE 4250 PSF SURCHARGEPLPLStatic Factor of Safety: 1.9Proposed Grading and House Location = 62 Ft Slope SetbackColor Name Unit Weight (pcf)Cohesion'(psf)Phi' (°)CL 120 200 28GM 125 100 30GP-GM 125 25 3662 FEET FROM TOP OF SLOPE15 FEET FROM PROPERTY LINE GP-GMGMCL1.3Distance0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310 320Elevation500510520530540550560570580590Elevation50051052053054055056057058059021-5865, Woodland Ridge Phases 3-8Geologic Cross-Section C to C'Post Construction - Seismic AnalysisPeak Ground Acceleration PGAm = 0.392g (1/2 PGAm = 0.196g)CC'GLACIER RDLOT 20, PHASE 4250 PSF SURCHARGEPLPLPseudostatic Factor of Safety: 1.3Proposed Grading and House Location = 62 Ft Slope SetbackColor Name Unit Weight (pcf)Cohesion'(psf)Phi' (°)CL 120 200 28GM 125 100 30GP-GM 125 25 3662 FEET FROM TOP OF SLOPE15 FEET FROM PROPERTY LINE GP-GMGMCL1.5Distance0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250Elevation500510520530540550560570580590Elevation50051052053054055056057058059021-5865, Woodland Ridge Phases 3-8Geologic Cross-Section D to D'Existing Condition - Static AnalysisDD'GLACIER RDLOT 14PLPLStatic Factor of Safety: 1.5With 25 Ft Slope SetbackColor Name Unit Weight (pcf)Cohesion'(psf)Phi' (°)CL 120 200 28GM 125 100 30GP-GM 125 25 3625 FEET GP-GMGMCL1.1Distance0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250Elevation500510520530540550560570580590Elevation50051052053054055056057058059021-5865, Woodland Ridge Phases 3-8Geologic Cross-Section D to D'Existing Condition - Seismic AnalysisPeak Ground Acceleration PGAm = 0.392g (1/2 PGAm = 0.196g)DD'GLACIER RDLOT 14PLPLPseudostatic Factor of Safety: 1.1With 40 Ft Slope SetbackColor Name Unit Weight (pcf)Cohesion'(psf)Phi' (°)CL 120 200 28GM 125 100 30GP-GM 125 25 3640 FEET GP-GMGMCL1.6Distance0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250Elevation500510520530540550560570580590Elevation50051052053054055056057058059021-5865, Woodland Ridge Phases 3-8Geologic Cross-Section D to D'Post Construction - Static AnalysisDD'GLACIER RDLOT 14250 PSF SURCHARGEPLPLStatic Factor of Safety: 1.6Proposed Grading and House Location = 40 Foot Slope SetbackColor Name Unit Weight (pcf)Cohesion'(psf)Phi' (°)CL 120 200 28GM 125 100 30GP-GM 125 25 3640 FEET FROM TOP OF SLOPE15 FEET FROM PROPERTY LINE GP-GMGMCL1.1Distance0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250Elevation500510520530540550560570580590Elevation50051052053054055056057058059021-5865, Woodland Ridge Phases 3-8Geologic Cross-Section D to D'Post Construction - Seismic AnalysisPeak Ground Acceleration PGAm = 0.392g (1/2 PGAm = 0.196g)DD'GLACIER RDLOT 14250 PSF SURCHARGEPLPLPseudostatic Factor of Safety: 1.1Proposed Grading and House Location = 40 Foot Slope SetbackColor Name Unit Weight (pcf)Cohesion'(psf)Phi' (°)CL 120 200 28GM 125 100 30GP-GM 125 25 3640 FEET FROM TOP OF SLOPE15 FEET FROM PROPERTY LINE Real-World Geotechnical Solutions Investigation • Design • Construction Support 14835 SW 72nd Avenue Tel (503) 598-8445 Portland, Oregon 97224 Fax (503) 941-9281 SITE RESEARCH WETLANDAREAPHASE 6PHASE 8PHASE 7PROJECT No: HORIZ: VERT: DRAWN BY: SCALE: DATE:REVISIONS: DESIGNED BY: REVIEWED BY:EXPIRES 12/22 SUBMITTALS:A & O Engineering L.L.C. 380 Q ST. SUITE 200SPRINGFIELD, OR. 97477PHONE: (541) 302-9790scott@aoengineering.biz CIVIL ENGINEERING & SITEDEVELOPMENT CONSULTING OVERVIEWASSESSOR'S MAP: 18-02-04-00 TAX LOT 2800 PHASE 3Stormwater Structure TableStructure NameST CI #1ST CI #2ST CI #3ST CI #4ST CI #5ST CI #6ST CI #7ST CI #8Structure Details RIM = 512.9010" INV OUT (NE)= 510.23 RIM = 512.9010" INV OUT (SW)= 510.37 RIM = 516.0710" INV OUT (NE)= 510.95 RIM = 518.3510" INV OUT (SW)= 511.13 RIM = 520.2710" INV OUT (N)= 511.70 RIM = 520.2710" INV OUT (S)= 511.88 RIM = 520.8610" INV OUT (E)= 514.96 RIM = 520.8610" INV OUT (W)= 514.82Stormwater Structure TableStructure NameST CI #9ST CI #10ST CI #11ST CI #12ST CI #13ST CI #14ST CI #15ST CI #16Structure Details RIM = 526.9210" INV OUT (E)= 521.04 RIM = 526.9210" INV OUT (W)= 520.90 RIM = 528.2010" INV OUT (N)= 524.81 RIM = 528.1210" INV OUT (S)= 524.95 RIM = 519.3810" INV OUT (N)= 510.51 RIM = 519.3810" INV OUT (S)= 510.69 RIM = 520.5010" INV OUT (W)= 513.93 RIM = 520.5010" INV OUT (E)= 514.11Stormwater Structure TableStructure NameST CI #19ST CI #20ST MH #1ST MH #2ST MH #3ST MH #4ST MH #5ST MH #6Structure Details RIM = 530.2210" INV OUT (S)= 523.41 RIM = 530.2210" INV OUT (N)= 523.36 RIM = 514.9821" INV IN (S)= 510.0921" INV OUT (NW)= 510.09 RIM = 515.0621" INV IN (SE)= 510.1718" INV OUT (NW)= 510.17 RIM = 515.7518" INV IN (SE)= 510.6418" INV OUT (NW)= 510.64 RIM = 516.6018" INV IN (SE)= 510.8610" INV IN (NE)= 510.8610" INV IN (SW)= 510.8615" INV OUT (W)= 510.86 RIM = 516.7215" INV IN (E)= 511.0215" INV OUT (W)= 511.02 RIM = 515.8215" INV IN (E)= 511.4512" INV IN (W)= 511.4515" INV OUT (N)= 511.45Stormwater Structure TableStructure NameST MH #7ST MH #8ST MH #9ST MH #10ST MH #11ST MH #12ST MH #13ST MH #14Structure Details RIM = 515.4710" INV IN (N)= 511.6110" INV IN (S)= 511.6112" INV OUT (E)= 511.61 RIM = 529.9212" INV IN (S)= 522.9215" INV OUT (E)= 522.92 RIM = 530.3215" INV IN (W)= 523.3215" INV OUT (E)= 523.32 RIM = 529.4115" INV IN (W)= 524.0315" INV OUT (E)= 524.03 RIM = 530.1212" INV IN (W)= 524.7410" INV IN (N)= 524.74 RIM = 514.8212" INV OUT (E)= 510.96 RIM = 515.7324" INV IN (S)= 510.0612" INV IN (W)= 510.0624" INV OUT (E)= 510.06 RIM = 517.9224" INV IN (W)= 510.2912" INV IN (E)= 510.2915" INV OUT (N)= 510.29Stormwater Structure TableStructure NameST MH #15ST MH #16ST MH #17ST MH #18ST MH #19ST MH #20ST MH #21ST MH #22Structure Details RIM = 518.5510" INV IN (N)= 510.4210" INV IN (S)= 510.4212" INV OUT (W)= 510.4212" INV OUT (E)= 510.42 RIM = 520.8415" INV IN (S)= 513.8410" INV IN (E)= 513.8410" INV IN (W)= 513.8415" INV OUT (N)= 513.84 RIM = 525.2215" INV IN (S)= 518.2215" INV OUT (N)= 518.22 RIM = 535.9915" INV IN (S)= 520.1912" INV IN (W)= 520.1912" INV IN (N)= 520.1912" INV OUT (E)= 520.19 RIM = 527.4112" INV IN (NW)= 523.5512" INV OUT (E)= 523.55 RIM = 527.6012" INV IN (NW)= 523.7412" INV OUT (SE)= 523.74 RIM = 529.5512" INV OUT (SE)= 524.07 RIM = 536.6510" INV IN (W)= 520.5812" INV IN (E)= 520.5812" INV OUT (S)= 520.58PROJECT No: HORIZ: VERT: DRAWN BY: SCALE: DATE:REVISIONS: DESIGNED BY: REVIEWED BY:EXPIRES 12/22 SUBMITTALS:A & O Engineering L.L.C. 380 Q ST. SUITE 200SPRINGFIELD, OR. 97477PHONE: (541) 302-9790scott@aoengineering.biz CIVIL ENGINEERING & SITEDEVELOPMENT CONSULTING Grading & Storm Drainage Plan West PHASE 6PHASE 7PHASE 4Stormwater Structure TableStructure NameST CI #21ST CI #22ST CI #23ST CI #24ST MH #24ST MH #25ST MH #26ST MH #27Structure Details RIM = 539.5110" INV OUT (N)= 534.89 RIM = 539.5110" INV OUT (S)= 535.03 RIM = 560.0310" INV OUT (N)= 554.84 RIM = 560.0310" INV OUT (S)= 554.98 RIM = 537.7515" INV IN (W)= 530.7515" INV OUT (E)= 530.75 RIM = 541.8215" INV IN (W)= 534.8210" INV IN (N)= 534.8210" INV IN (S)= 534.8212" INV OUT (E)= 534.82 RIM = 553.4912" INV IN (W)= 546.4912" INV OUT (E)= 546.49 RIM = 561.7712" INV IN (W)= 554.7710" INV IN (N)= 554.7710" INV IN (S)= 554.77PROJECT No: HORIZ: VERT: DRAWN BY: SCALE: DATE:REVISIONS: DESIGNED BY: REVIEWED BY:EXPIRES 12/22 SUBMITTALS:A & O Engineering L.L.C. 380 Q ST. SUITE 200SPRINGFIELD, OR. 97477PHONE: (541) 302-9790scott@aoengineering.biz CIVIL ENGINEERING & SITEDEVELOPMENT CONSULTING Grading & Storm Drainage Plan East ******+******+**+++++A++*****(((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((( ((( ((( ((( ((( ((( ((((((((((((((((((((((((((((((((((( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((( ( (((((((((((((((((((((((((((((((((((((((((((((( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((( ( ( ( ( ((( ( ( ( ( ( ( ( ( ( (((((((((( (((((( ( ((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((( (((( (((((((((((((((((((((((((((((((((((((( (((((((((((( ((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((( R R R R R R R R R R R R R R R R ( R (( R R L 75+2 4. 0 6 24.19CH14.10CH503.76'S65 ° E 303. 6 ' 33.92CH N58°E 10.36 C H 683.76'20.00CH 21.32CHN71° W 4 . 3 2 C H 318.1 2 '358.50'30 1 . 5 'S00°19'52"E542.17'L 81+25.81 S54°W 6.70 C H S83°00'45"E 7 5 7 . 3 2 'S00°04'E8.17CH (539.22')9 49 4 8 5 LN. JESSIC A L N 5 8 TH KALMIANO. 452COUNTYROAD59THSTREET3 10 1/4 COR (APPROX) 33 4 3 34 STREETS89°58'32"W 444.86' S89°33'37"W 1788.78' & 60' 60'208'SOUTH 367.02'EAST 314.13'178.53'DLC NO 86 T D EDWARDS SE COR 436.07' N89°10'W S P S67° 2 1 ' 4 6 " E 226.1 9 ' EAST 373.93'SOUTHBOOTH WEYERHAEUSER 374.66' KELLY R RNORTH 449.06'251.5'523.60' NORTHNE COR N89°49'18"W 1317.8' (SURV #20630)N00°22'W(254.29')279.73'SOUTHWEST 120'460.33'N3°25'EEAST NORTH S89°30'W N87°50'40"W ROAD 208.71' ENE COR 1368.52' = 15CH (DLC)30'S00°22'E327.75' 110.83'682.54 'SOUTH 910.50'191.43' 244.61'212.50'N3°26'ES0°23'10"W 710.40'268.14' N86°48'E 661'119' 589.09'S65°56'39"E318.8'157.13'SOUTH 208'SE COR 270.50' N53°37'30"E 2 1 3 . 0 2 '60'N0°15'35"E 815.54'402.79'S0°24'25"WSOUTH 444.32'WEST DLC NO 49 DLC NO 63 S89°38'W 28.85CHN00°12'11"W 932.66'S 4 4 ° 5 1 ' E A HAMITT DLC NO 49 N00°10'01"E 2183.35'270.50' 1 9 3 . 6 0 ' (345.11') 309.70' 1064.78'478.8'N89°44'30"E 589.40' N89°54'W 300'SOUTH 57RDS (340.5')347.15 ' S89°54'45"W 871.9' N89°54'W 964.55' 8 5 ' 266.61'269.67'266.61'120'686.2'100'70'S00°04'E 8.17 CH (539.22')N89°52'W 225.54' S89°25'W316'N89°58'E (SURV #20630)442.26'365'112.87'108.54'8 5 ' 205.48' 1489'686.2'205.25' 3300N3°25'E371'240'60'46.89'N89°25'40"E 23.80 CHS 301 EAST LINE DLC NO 472900 2905 2913 33 1503 SE COR DAVID ARTHUR DLC 63 32 1100 1000 2901 1500 2902 2907 2912 2917 2001 2700 13.54 AC.S 9.72 AC.S. 2918 2000 1507 8.78 AC.S 30.73 AC.S. 1200 900 2908 2911 5 1508 2300 31.43 AC.S 23.21 AC.S. 1300 SW COR DLC 47 2903 2910 2916 4 150526.38 AC.S 2.67 AC.S 4.44 AC.S. 305 1400 WNW COR P GORDON DLC 62 2904 2909 2915 1504 2100 85.86 AC.S CO. RD . 2273 0.84 AC.S. LOT 3 5.24 60'ROA D 176' M / L 157' WEST 314.13' S89°38"W 725.45'300'N89°53'20"E 339.16'241.03'WEST N 4 0 ° 3 4 'W N 4 0 ° 3 4 'W 225.54' S89°48'30"E 118.13'N37°08'EN86°48'E 289'20' S75°11' 3 2 " E S00°19'52"E 542.17'304 303 SSE COR RG HIXON DLC 47 SE COR DLC 62 INT ELL COR DLC 62 2906 2914 1700 1501 26.03 AC.S 3.30 AC.S JASPER ROAD CO R D 2 2 7 3 ( H W Y 2 2 2 ) JAS P E R R D C O R D 2273(HWY222)SOUTH293.6'COUNT Y S 20630 1.95 AC.S S76°26'3 9 " E 6 4 7 . 7 3 ' 311 PHAS E 1 310 22'1250.33'PHAS E 1 313 1435.78' 244. 1 7 ' N89°52'01"E N89°56'05"E 64.91' S0°03'55"E 426.72'S0°24'30"WN65 ° 0 0 ' 2 1 " W 200.23' 256.72' N0°03'55"W136.47'S0°18'24"W 35.24' N89°59'10"W N0°24'25"E 401.89'N01°14'37"EN89°56'05"E 75' N89°56'05"E 2868' 250' 60'527.82'N89°56'49"E N86°56'05"E 1482.41'209'225'241'195'S1°06'23"E206'30' 195' PCL 1 PCL 2 PCL 3 1502 S. 45045 2020-P29432801 1.43 AC 8.98 AC5.92 AC 1.86 AC 0.98 AC99.85 AC 0.59 AC 1.5 AC 12.08 AC 0.72 AC1 AC 0.74 AC1.96 AC54.36 AC 0.34 AC 2.28 AC 72.36 AC 0.63 AC 34.1 AC 1.79 AC 8.97 AC 9.84 AC 0.23 AC 1.16 AC 0.92 AC 6.96 AC 8.88 AC 2400 25002401 3400 27032600 1800 3001 2701 32003201 300330023000 308 307 2800 1511 2702 312 3100 200 300 1509 1510 6400 019-00 019-38 019-15 019-32 019-15 019-38019-15 019-01 019-35 019-32 019-37 019-00 019-35 019-38 019-32SEE MAP 18020900 SEE MAP 18020500 SEE MAP 18020411 SEE MAP 18020442 SEE MAP 18020414 SEE MAP 18020332 SEE MAP 18020422 SEE MAP 18020511 SEE MAP 17023300 SEE MAP 18020421 SEE MAP 18020333 SEE MAP 18020323 SEE MAP 18020412 SEE MAP 18020800 SEE MAP 17023344 SEE MAP 18020413 SEE MAP 17023333 SEE MAP 17023433 SEE MAP 17023244 SEE MAP 17023334 SEE MAP 18020300 SEE MAP 18020322 SEE MAP 17023200 FOR ASSESSMENT AND TAXATION ONLY SECTION 4 T.18S. R.2W. W.M.Lane County 1" = 400' CANCELLED 1500 100 101 102 301 302 303 304 305 306 307 309 400 500 501 600 700 800 900 901 1000 1100 1200 1300 1400 1500 1501 1502 1503 1504 1505 1506 1507 1508 1600 1700 1900 2000 2001 2100 2200 2300 2700 2900 2901 2902 2903 2904 2905 2906 2907 2908 2909 2910 2911 2912 2913 2914 2915 2916 2917 2918 3300 311 313 310 2800 1502 2801 18020400 SPRINGFIELD SPRINGFIELD 18020400 LCATSKP - 2021-01-27 12:01 REVISIONS 08/21/2008 - LCAT167 - CONVERT MAP TO GIS 09/17/2010 - LCAT167 - ADDED "CO RD 2273" TO JASPER RD 04/12/2013 - LCAT155 - CODE CHANGE TLs 3000, 3002, & 3201 03/02/2015 - LCAT174 - CODE CHANGE TL 313 07/28/2015 - LCAT174 - CANC 310, 311, 313 TO PINEHURST PHASE 1 01/16/2018 - LCAT174 - LLA BETWEEN TL 2800 & TL 2801 05/06/2020 - LCAT148 - CANC TL 1502 INTO 2020-P2943 01/07/2021 - LCAT148 - PTN OF TL 3100 OUT TO ROAD 01/27/2021 - LCAT148 - CANC TL 2801 INTO WOODLAND RIDGE PHASE 1 9/22/21, 2:30 PM ATC Hazards by Location https://hazards.atcouncil.org/#/seismic?lat=44.037138&lng=-122.938705&address=1/2 Hazards by Location Search Information Coordinates:44.037138, -122.938705 Elevation:542 ft Timestamp:2021-09-22T21:30:45.377Z Hazard Type:Seismic Reference Document: NEHRP-2015 Risk Category:II Site Class:D MCER Horizontal Response Spectrum Design Horizontal Response Spectrum Basic Parameters Name Value Description SS 0.637 MCER ground motion (period=0.2s) S1 0.369 MCER ground motion (period=1.0s) SMS 0.822 Site-modified spectral acceleration value SM1 * 0.712 Site-modified spectral acceleration value SDS 0.548 Numeric seismic design value at 0.2s SA SD1 * 0.475 Numeric seismic design value at 1.0s SA * See Section 11.4.7 Additional Information Name Value Description SDC * D Seismic design category Fa 1.29 Site amplification factor at 0.2s Fv * 1.931 Site amplification factor at 1.0s 542 ft Map data ©2021 Google 0 5 10 15 Period (s) 0.00 0.20 0.40 0.60 0.80 Sa(g) 0 5 10 15 Period (s) 0.00 0.10 0.20 0.30 0.40 0.50 Sa(g) 9/22/21, 2:30 PM ATC Hazards by Location https://hazards.atcouncil.org/#/seismic?lat=44.037138&lng=-122.938705&address=2/2 CRS 0.866 Coefficient of risk (0.2s) CR1 0.856 Coefficient of risk (1.0s) PGA 0.302 MCEG peak ground acceleration FPGA 1.298 Site amplification factor at PGA PGAM 0.392 Site modified peak ground acceleration TL 16 Long-period transition period (s) SsRT 0.637 Probabilistic risk-targeted ground motion (0.2s) SsUH 0.736 Factored uniform-hazard spectral acceleration (2% probability of exceedance in 50 years) SsD 1.5 Factored deterministic acceleration value (0.2s) S1RT 0.369 Probabilistic risk-targeted ground motion (1.0s) S1UH 0.431 Factored uniform-hazard spectral acceleration (2% probability of exceedance in 50 years) S1D 0.6 Factored deterministic acceleration value (1.0s) PGAd 0.5 Factored deterministic acceleration value (PGA) * See Section 11.4.7 The results indicated here DO NOT reflect any state or local amendments to the values or any delineation lines made during the building code adoption process. Users should confirm any output obtained from this tool with the local Authority Having Jurisdiction before proceeding with design. Disclaimer Hazard loads are provided by the U.S. Geological Survey Seismic Design Web Services. While the information presented on this website is believed to be correct, ATC and its sponsors and contributors assume no responsibility or liability for its accuracy. The material presented in the report should not be used or relied upon for any specific application without competent examination and verification of its accuracy, suitability and applicability by engineers or other licensed professionals. ATC does not intend that the use of this information replace the sound judgment of such competent professionals, having experience and knowledge in the field of practice, nor to substitute for the standard of care required of such professionals in interpreting and applying the results of the report provided by this website. 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Woodland Ridge State of Oregon, State of Oregon GEO, Esri, HERE, Garmin, iPC, Maxar Bare Earth Lidar Hillshade High : 11243 Low : -22 July 21, 2021 0 0.09 0.170.04 mi 0 0.1 0.20.05 km 1:7,200 Woodland Ridge LHS State of Oregon, State of Oregon GEO, Esri, HERE, Garmin, iPC, Maxar Landslide Hazard Low - Landsliding Unlikely Moderate - Landsliding Possible High - Landsliding Likely Very High - Existing Landslide Bare Earth Lidar Hillshade High : 11243 Low : -22 July 21, 2021 0 0.09 0.170.04 mi 0 0.1 0.20.05 km 1:7,200 Real-World Geotechnical Solutions Investigation • Design • Construction Support 14835 SW 72nd Avenue Tel (503) 598-8445 Portland, Oregon 97224 Fax (503) 941-9281 PHOTOGRAPHIC LOG Real-World Geotechnical Solutions Investigation • Design • Construction Support WOODLAND RIDGE PHASES 3-8 GEOTECHNICAL INVESTIGATION PHOTOGRAPHIC LOG Page 1 Woodland Ridge Site, Open Area, Facing East Real-World Geotechnical Solutions Investigation • Design • Construction Support WOODLAND RIDGE PHASES 3-8 GEOTECHNICAL INVESTIGATION PHOTOGRAPHIC LOG Page 2 North Side of Site is Heavily Wooded and Slopes to the North Real-World Geotechnical Solutions Investigation • Design • Construction Support WOODLAND RIDGE PHASES 3-8 GEOTECHNICAL INVESTIGATION PHOTOGRAPHIC LOG Page 3 Northern Edge of Property, Slope Obscured by Vegetation Sloping Area, Facing East Real-World Geotechnical Solutions Investigation • Design • Construction Support WOODLAND RIDGE PHASES 3-8 GEOTECHNICAL INVESTIGATION PHOTOGRAPHIC LOG Page 4 Test Pits Test Pits Real-World Geotechnical Solutions Investigation • Design • Construction Support WOODLAND RIDGE PHASES 3-8 GEOTECHNICAL INVESTIGATION PHOTOGRAPHIC LOG Page 5 Test Pit and Typical Soil Profile Real-World Geotechnical Solutions Investigation • Design • Construction Support WOODLAND RIDGE PHASES 3-8 GEOTECHNICAL INVESTIGATION PHOTOGRAPHIC LOG Page 6 Test Pit and Typical Soil Profile Real-World Geotechnical Solutions Investigation • Design • Construction Support WOODLAND RIDGE PHASES 3-8 GEOTECHNICAL INVESTIGATION PHOTOGRAPHIC LOG Page 7 Test Pit and Typical Soil Profile Real-World Geotechnical Solutions Investigation • Design • Construction Support WOODLAND RIDGE PHASES 3-8 GEOTECHNICAL INVESTIGATION PHOTOGRAPHIC LOG Page 8 Test Pit with Infiltration Testing Test Pit with Infiltration Testing Real-World Geotechnical Solutions Investigation • Design • Construction Support WOODLAND RIDGE PHASES 3-8 GEOTECHNICAL INVESTIGATION PHOTOGRAPHIC LOG Page 9 CME-75 Mud-Rotary Soil Boring Rig