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22-102583-SE-Geotechnical Report-06-10-2022-V1 GEOTECHNICAL REPORT Federal Way Assemblage Milton Road South and South 376th Street Federal Way, Washington Project No. T-8562 Prepared for: Pulte Homes of Washington, Inc. Bellevue, Washington January 28, 2022 Revised June 3, 2022 6-3-2022 TABLE OF CONTENTS Page No. 1.0 Project Description .......................................................................................................... 1 2.0 Scope of Work ................................................................................................................. 1 3.0 Site Conditions ................................................................................................................ 2 3.1 Surface ................................................................................................................ 2 3.2 Subsurface .......................................................................................................... 2 3.3 Groundwater ....................................................................................................... 3 3.4 Geologic Hazards ............................................................................................... 3 3.4.1 Erosion Hazard Areas ............................................................................... 3 3.4.2 Landslide Hazard Areas ........................................................................... 4 3.4.3 Seismic Hazard Areas ............................................................................... 5 3.5 Seismic Site Class .............................................................................................. 5 4.0 Discussion and Recommendations .................................................................................. 5 4.1 General ............................................................................................................... 5 4.2 Site Preparation and Grading .............................................................................. 6 4.3 Excavations ........................................................................................................ 7 4.4 Foundation Support ............................................................................................ 7 4.5 Slab-on-Grade Floors ......................................................................................... 8 4.6 Lateral Earth Pressures for Below-Grade Walls ................................................. 8 4.7 Stormwater Facilities .......................................................................................... 9 4.8 Infiltration Feasibility ......................................................................................... 9 4.9 Drainage ............................................................................................................. 9 4.10 Utilities ............................................................................................................. 10 4.11 Pavements ......................................................................................................... 10 5.0 Additional Services ....................................................................................................... 11 6.0 Limitations ..................................................................................................................... 11 Figures Vicinity Map ......................................................................................................................... Figure 1 Exploration Location Plan .................................................................................................... Figure 2 Typical Wall Drainage Detail ............................................................................................... Figure 3 Appendix Field Exploration and Laboratory Testing ........................................................................ Appendix A Geotechnical Report Federal Way Assemblage Milton Road South and South 376th Street Federal Way, Washington 1.0 PROJECT DESCRIPTION The project consists of developing the site with 84 single-family residential building lots, two stormwater ponds, associated access, and utilities. Based on Preliminary Grading Plans prepared by ESM Consulting Engineers, LLC, dated May 23, 2022, cuts and fills ranging from approximately 1 to 12 feet will be required to achieve final building pad elevations across the site. Site stormwater will be collected and directed to one of two stormwater ponds located at Tracts N and O in the western and southeastern portions of the site, respectively. We expect the residential buildings constructed on the lots will be a two- to- three-story, wood-framed building constructed over a crawlspace with an attached garage constructed at-grade. Structural loading should be relatively light, with bearing walls carrying loads of 2 to 3 kips per foot and isolated columns carrying maximum loads of 30 to 40 kips. The recommendations in the following sections of this report are based on our understanding of the preceding design features. We should review design drawings as they become available to verify our recommendations have been properly interpreted and to supplement them, if required. 2.0 SCOPE OF WORK On June 1, 2021, and June 4, 2021, we observed soil and groundwater conditions at 30 soil test pits excavated with a mini-excavator to maximum depths of approximately six to ten feet below existing grades. On June 7, 2021, we supplemented this data by drilling four test borings to maximum depths of approximately 15 feet below existing grades. Using the information obtained from the subsurface exploration, we performed analyses to develop geotechnical recommendations for project design and construction. Specifically, this report addresses the following:  Soil and groundwater conditions.  Geologic Hazards per the City of Federal Way Municipal Code.  Seismic Site Class per the current International Building Code (IBC).  Site preparation and grading.  Excavations. January 28, 2022 Revised June 3, 2022 Project No. T-8562 Page No. 2  Foundation support.  Slab-on-grade floors.  Stormwater facilities.  Lateral earth pressures for below-grade walls.  Infiltration feasibility.  Drainage.  Utilities.  Pavements. It should be noted, recommendations outlined in this report regarding drainage are associated with soil strength, design earth pressures, erosion, and stability. Design and performance issues with respect to moisture as it relates to the structure environment are beyond Terra Associates, Inc.’s purview. A building envelope specialist or contactor should be consulted to address these issues, as needed. 3.0 SITE CONDITIONS 3.1 Surface The site consists of nine residential tax parcels totaling about 33.62 acres located northeast of the intersection of Milton Road South and South 376th Street in Federal Way, Washington. The approximate site location is shown on Figure 1. The site is currently developed seven single-family homes, three detached outbuildings, and associated landscaping and access. The southwestern portion of the site is covered with a moderate forest and associated understory. Site topography consists of a slope that descends from the northeast to the south-southwest with an overall relief of approximately 45 feet. 3.2 Subsurface In general, the soil conditions at the site generally consist of approximately 3 to 12 inches of organic topsoil overlying approximately three to seven feet of medium dense silty sand with gravel in the test pits located in the northeast, east, and southwest portions of the site, and approximately two to eight feet of stiff to very stiff silt with varying sand and gravel contents in the west, central, and south portions of the site. The vast majority of the test pits and all four test borings terminated in dense to very dense silty sand with gravel (unweathered till). Exceptions to this general condition were observed in Test Boring B-1 where approximately 14 feet of medium dense to very dense sands and gravels were observed overlying the very dense, unweathered till deposits, and at Test Pits TP-12 and TP-26, where the test pits exposed and terminated in medium dense to dense outwash sands and gravels underlying up to three feet of medium dense silty sand with gravel. January 28, 2022 Revised June 3, 2022 Project No. T-8562 Page No. 3 The Geologic Map of the Poverty Bay 7.5’ Quadrangle, King and Pierce Counties, Washington by D.B. Booth, H.H. Waldron, and K.G. Troost (2004) maps the western portion of the site as Recessional Outwash (Qvr) and the east portion as Glacial Till (Qvt). These mapped descriptions are consistent with the native soils observed in the test pit and test boring locations. The preceding discussion is intended to be a general review of the soil conditions encountered. For more detailed descriptions, please refer to the Test Pit Logs and Test Boring logs in Appendix A. The approximate location of the test pits is shown on the Exploration Location Plan, Figure 2. 3.3 Groundwater We observed light perched groundwater seepage in Test Borings B-2 and B-3 around pockets of gravel and in interbedded sand with silt layers contained with the greater till deposits. Additionally, slightly mottled soils were observed in some of the test pits which indicates the presence of perched groundwater seepage throughout much of the site. The occurrence of shallow perched groundwater is typical for sites underlain by fine-grained soils. We expect perched groundwater levels and flow rates will fluctuate seasonally and will typically reach their highest levels during and shortly following the wet winter months (November through April). 3.4 Geologic Hazards We evaluated site conditions for the presence of Geologically Hazardous Areas as defined in Chapter 19 of the City of Federal Way Revised Code (FWRC). Discussions related to erosion, landslide, and seismic hazards are given below. 3.4.1 Erosion Hazard Areas Chapter 19.05.070(1) of the FWRC defines Erosion Hazard Areas as “…those areas identified by the U.S. Department of Agriculture’s Natural Resource Conservation Service as having a moderate to severe or severe to very severe rill and inter-rill erosion hazard due to natural agents such as wind, rain, splash, frost action or stream flow; those areas containing the following group of soils when they occur on slopes of 15 percent or greater: Alderwood-Kitsap (“AkF”), Alderwood gravelly sandy loam (“AgD”), Kitsap silt loam (“KpD”), Everett (“EvD”), and Indianola (“InD”); and those areas impacted by shore land and/or stream bank erosion.” The soils observed onsite are classified as Alderwood gravelly sandy loam, 8 to 15 percent slopes, Everett very gravelly sandy loam, 8 to 15 percent slopes, and Kitsap silt loam, 2 to 8 percent slopes by the United States Department of Agriculture Natural Resources Conservation Service (NRCS). Across the site, with the existing slope gradients, these soils will have a slight to moderate potential for erosion when exposed. Therefore, the site does not meet the above criteria for an erosion hazard area as defined by the FWRC in our opinion. Regardless, the site soils would be susceptible to some erosion when exposed during construction. In our opinion, proper implementation, and maintenance of Best Management Practices (BMPs) for erosion prevention and sediment control would adequately mitigate the erosion potential in the planned development area. Erosion protection measures, as required by the City of Federal Way, will need to be in place prior to and during grading activities at the site. January 28, 2022 Revised June 3, 2022 Project No. T-8562 Page No. 4 3.4.2 Landslide Hazard Areas Landslide Hazard Areas are defined in Chapter 19.05.070(2) of the FWRC as “…those areas potentially subject to episodic downslope movement of a mass of soil or rock including, but not limited to, the following areas: (a) Any area with a combination of: (i) Slopes greater than 15 percent. (ii) Permeable sediment, predominately sand and gravel, overlying relatively impermeable sediment or bedrock, typically silt and clay; and (iii) Springs or groundwater seepage. (b) Any area that has shown movement during the Holocene epoch, from 10,000 years ago to the present, or that is underlain by mass wastage debris of that epoch. (c) Any area potentially unstable as a result of rapid stream incision, stream bank erosion or undercutting by wave action. (d) Any area located in a ravine or on an active alluvial fan, presently or potentially subject to inundation by debris flows or flooding. (e) Those areas mapped as Class U (unstable), UOS (unstable old slides), and URS (unstable recent slides) by the Department of Ecology’s Coastal Zone Atlas. (f) Areas designated as quaternary slumps, earthflows, mudflows, lahars, or landslides on maps published by the U.S. Geological Survey or Washington State Department of Natural Resources. (g) Slopes having gradients greater than 80 percent subject to rockfall during seismic shaking. (h) Any area with a slope of 40 percent or steeper and with a vertical relief of 10 or more feet except areas composed of consolidated rock. A slope is delineated by establishing its toe and top and is measured by averaging the inclination over at least 10 feet of vertical relief.” The site is not mapped as a potential landslide hazard area by the King County iMap, nor is it designated as a landslide hazard area on the Washington State Department of Natural Resources’ King County Landslide Hazard Areas Map prepared in May 2010. Existing site topography consists of a slope underlain by relatively shallow, cemented glacial till with little to no risk of mass movement due to geologic, topographic, or hydrologic factors. Therefore, in our opinion, the site is not a landslide hazard area as defined by the FWRC. January 28, 2022 Revised June 3, 2022 Project No. T-8562 Page No. 5 3.4.3 Seismic Hazard Areas Chapter 19.05.070(3) of the FWRC defines Seismic Hazard Areas as “…those areas subject to severe risk of earthquake damage as a result of seismically induced ground shaking, slope failure, settlement or soil liquefaction, or surface faulting. These conditions occur in areas underlain by cohesionless soils of low density usually in association with a shallow groundwater table.” A review of a map titled Faults and Earthquakes in Washington State, dated 2014 by Jessica L. Czajkowski and Jeffrey D. Bowman shows the nearest fault is categorized as “Class B” and is located approximately four miles northeast of the site. Accordingly, during a seismic event, the risk of ground rupture along a fault line at the site is low. Liquefaction is a phenomenon where there is a reduction or complete loss of soil strength due to an increase in water pressure induced by vibrations. Liquefaction mainly affects geologically recent deposits of fine-grained sands underlying the groundwater table. Soils of this nature derive their strength from intergranular friction. The generated water pressure or pore pressure essentially separates the soil grains and eliminates this intergranular friction, thus eliminating the soil’s strength. The site is currently mapped on the Washington State DNR’s King County Liquefaction Susceptibility Map, dated May 2010, as having very low liquefaction potential. Based on the soil and groundwater conditions we observed, it is our opinion that the risk for soil liquefaction occurring at the site is negligible due to the relative density of the soils and amount of cohesive material that would be sufficient to resist the cyclical loading of a seismic event. Therefore, in our opinion, the site would not be considered a seismic hazard area as defined by the FWRC. 3.5 Seismic Site Class Based on soil conditions observed in the test pits and test borings, and our knowledge of the area geology, per Chapter 16 of the 2018 International Building Code (IBC), Site Class “D” should be used in structural design. 4.0 DISCUSSION AND RECOMMENDATIONS 4.1 General Based on our study, there are no geotechnical considerations that would preclude development of the site as currently planned. The residential buildings can be supported on conventional spread footings bearing on competent native soils observed below the organic surface horizon, or on structural fill placed above the competent soils. Pavement and floor slabs can be similarly supported. A majority of the native soils encountered at the site contain a sufficient amount of soil fines that will make them difficult to compact as structural fill when too wet. The ability to use the native soils from site excavations as structural fill will depend on its moisture content and the prevailing weather conditions at the time of construction. The following sections provide detailed recommendations regarding the preceding issues and other geotechnical design considerations. These recommendations should be incorporated into the final design drawings and construction specifications. January 28, 2022 Revised June 3, 2022 Project No. T-8562 Page No. 6 4.2 Site Preparation and Grading To prepare the site for construction, all vegetation, organic surface soils, and other deleterious material should be stripped and removed from the site. Surface stripping depths of approximately 3 to 12 inches should be expected to remove the organic surface soils and vegetation. In the developed portions of the site, demolition of existing structures should include removal of existing foundations and abandonment of underground septic systems and other buried utilities. Abandoned utility pipes that fall outside of new building areas can be left in place provided they are sealed to prevent intrusion of groundwater seepage and soil. Organic topsoil will not be suitable for use as structural fill but may be used for limited depths in nonstructural areas. Once clearing and stripping operations are complete, cut and fill operations can be initiated to establish desired building grades. Prior to placing fill, all exposed bearing surfaces should be observed by a representative of Terra Associates, Inc. to verify soil conditions are as expected and suitable for support of new fill or building elements. Our representative may request a proofroll using heavy rubber-tired equipment to determine if any isolated soft and yielding areas are present. If excessively yielding areas are observed and they cannot be stabilized in place by compaction, the affected soils should be excavated and removed to firm bearing and grade restored with new structural fill. If the depth of excavation to remove unstable soils is excessive, the use of geotextile fabrics such as Mirafi 500X or an equivalent fabric can be used in conjunction with clean granular structural fill. Our experience has shown, in general, a minimum of 18 inches of a clean, granular structural fill placed and compacted over the geotextile fabric should establish a stable bearing surface. A majority of the native soils encountered at the site contain a sufficient amount of soil fines that will make them difficult to compact as structural fill when too wet or too dry. The ability to use native soils from site excavations as structural fill will depend on its moisture content, the prevailing weather conditions at the time of construction and the contractor’s ability to compact the native silt soils. If wet soils are encountered, the contractor will need to dry the soils by aeration during dry weather conditions. Alternatively, the use of an additive such as Portland cement, cement kiln dust (CKD), or lime to stabilize the soil moisture can be considered. If the soil is amended, additional Best Management Practices (BMPs) addressing the potential for elevated pH levels will need to be included in the Stormwater Pollution Prevention Program (SWPPP) prepared with the Temporary Erosion and Sedimentation Control (TESC) plan. If grading activities are planned during the wet winter months, or if they are initiated during the summer and extend into fall and winter, the owner should be prepared to import wet-weather structural fill. For this purpose, we recommend importing a granular soil that meets the following grading requirements: U.S. Sieve Size Percent Passing 6 inches 100 No. 4 75 maximum No. 200 5 maximum* * Based on the 3/4-inch fraction. Prior to use, Terra Associates, Inc. should examine and test all materials imported to the site for use as structural fill. January 28, 2022 Revised June 3, 2022 Project No. T-8562 Page No. 7 Structural fill should be placed in uniform loose layers not exceeding 12 inches and compacted to a minimum of 95 percent of the soil’s maximum dry density, as determined by American Society for Testing and Materials (ASTM) Test Designation D-1557 (Modified Proctor). The moisture content of the soil at the time of compaction should be within two percent of its optimum, as determined by this ASTM standard. In nonstructural areas, the degree of compaction can be reduced to 90 percent. 4.3 Excavations All excavations at the site associated with confined spaces, such as utility trenches, must be completed in accordance with local, state, and federal requirements. Based on regulations outlined in the Washington Industrial Safety and Health Act (WISHA), the upper, medium dense granular soils would be classified as Type C soils. The upper stiff to very stiff silts would be classified as Type B soils. The lower dense to very dense, unweathered soils would be Classified as Type A soils. Accordingly, temporary excavations in Type C soils should have their slopes laid back at an inclination of 1.5:1 (Horizontal: Vertical) or flatter, from the toe to the crest of the slope. Side slopes in Type B soils can be laid back at a slope inclination of 1:1 or flatter. Side slopes in Type A soils can be laid back at a slope inclination of 0.75:1 or flatter. For temporary excavation slopes less than 8 feet in height in Type A soils, the lower 3.5 feet can be cut to a vertical condition, with a 0.75:1 slope graded above. For temporary excavation slopes greater than 8 feet in height up to a maximum height of 12 feet, the slope above the 3.5-foot vertical portion will need to be laid back at a minimum slope inclination of 1:1. No vertical cut with a backslope immediately above is allowed for excavation depths exceeding 12 feet. In this case, a four-foot vertical cut with an equivalent horizontal bench to the cut slope toe is required. All exposed temporary slope faces that will remain open for an extended period of time should be covered with a durable reinforced plastic membrane during construction to prevent slope raveling and rutting during periods of precipitation. The above information is provided solely for the benefit of the owner and other design consultants and should not be construed to imply that Terra Associates, Inc. assumes responsibility for job site safety. It is understood that job site safety is the sole responsibility of the project general contractor. 4.4 Foundation Support The residential buildings may be supported on conventional spread footing foundations bearing on competent native soils or on structural fill placed above the competent soils. Foundation subgrade should be prepared as recommended in Section 4.2 of this report. Perimeter foundations exposed to the weather should bear a minimum depth of one and one-half feet below final exterior grades for frost protection. Interior foundations can be constructed at any convenient depth below the floor slab. Foundations bearing on competent soil, can be dimensioned for a net allowable bearing capacity of 2,500 pounds per square foot (psf). For short-term loads, such as wind and seismic, a one-third increase in this allowable capacity can be used. With structural loading as anticipated and this bearing stress applied, estimated total settlements are less than one-half inch. January 28, 2022 Revised June 3, 2022 Project No. T-8562 Page No. 8 For designing foundations to resist lateral loads, a base friction coefficient of 0.30 can be used. Passive earth pressures acting on the side of the footing and buried portion of the foundation stem wall can also be considered. We recommend calculating this lateral resistance using an equivalent fluid weight of 350 pcf. We recommend not including the upper 12 inches of soil in this computation because they can be affected by weather or disturbed by future grading activity. This value assumes the foundation will be constructed neat against competent existing fill, native soil, or backfilled with structural fill as described in Section 4.2 of this report. The values recommended include a safety factor of 1.5. 4.5 Slab-on-Grade Floors Slab-on-grade floors may be supported on subgrade prepared as recommended in Section 4.2 of this report. Immediately below the floor slab, we recommend placing a four-inch-thick capillary break layer composed of clean, coarse sand or fine gravel that has less than five percent passing the No. 200 sieve. This material will reduce the potential for upward capillary movement of water through the underlying soil and subsequent wetting of the floor slab. The capillary break layer will not prevent moisture intrusion through the slab caused by water vapor transmission. Where moisture by vapor transmission is undesirable, such as covered floor areas, a common practice is to place a durable plastic membrane on the capillary break layer and then cover the membrane with a layer of clean sand or fine gravel to protect it from damage during construction and to aid in uniform curing of the concrete slab. It should be noted, if the sand or gravel layer overlying the membrane is saturated prior to pouring the slab, it will not be effective in assisting uniform curing of the slab and can actually serve as a water supply for moisture bleeding through the slab, potentially affecting floor coverings. Therefore, in our opinion, covering the membrane with a layer of sand or gravel should be avoided if floor slab construction occurs during the wet winter months and the layer cannot be effectively drained. We recommend floor designers and contractors refer to the current American Concrete Institute (ACI) Manual of Concrete Practice for further information regarding vapor barrier installation below slab-on-grade floors. 4.6 Lateral Earth Pressures for Below-Grade Walls The magnitude of earth pressure development on below-grade walls will partly depend on the quality of the wall backfill. We recommend placing and compacting wall backfill as structural fill as described in Section 4.2 of this report. To guard against hydrostatic pressure development, wall drainage must also be installed. A typical recommended wall drainage detail is shown on Figure 3. With wall backfill placed and compacted as recommended, and drainage properly installed, we recommend designing unrestrained walls for an active earth pressure equivalent to a fluid weighing 35 pounds per cubic foot (pcf). For restrained walls, an additional uniform load of 100 psf should be added to the 35 pcf. To account for typical traffic surcharge loading, the walls can be designed for an additional imaginary height of two feet (two-foot soil surcharge). For evaluation of wall performance under seismic loading, a uniform pressure equivalent to 8H psf, where H is the height of the below-grade portion of the wall, should be applied in addition to the static lateral earth pressure. These values assume a horizontal backfill condition and that no other surcharge loading, sloping embankments, or adjacent buildings will act on the wall. If such conditions exist, then the imposed loading must be included in the wall design. Friction at the base of foundations and passive earth pressure will provide resistance to these lateral loads. Values for these parameters are provided in Section 4.4 of this report. January 28, 2022 Revised June 3, 2022 Project No. T-8562 Page No. 9 4.7 Stormwater Facilities As noted above, site stormwater will be collected and directed to two stormwater ponds located in the western and southeastern portions of the site. If fill berms will be constructed, the berm locations should be stripped of topsoil, duff, and soils containing organic material prior to the placement of fill. The fill berms should be constructed by placing structural fill in accordance with recommendations outlined in Section 4.2 of this report. Material used to construct pond berms should consist of predominately granular soils with a maximum size of 3 inches and a minimum of 20 percent fines. Terra Associates, Inc. should examine and test all onsite or imported materials proposed for use as berm fill prior to their use. It is possible that pockets of sandy or gravelly soils may be exposed within the pond areas. Therefore, it may be necessary to line the dead storage portion of the pond for water quality purposes depending on the final grades and exposed soils. Because of exposure to fluctuating stored water levels and wave action, soils exposed on the interior side slopes of the ponds may be subject to some risk of periodic shallow instability or sloughing. Establishing interior slopes at a 3:1 gradient will significantly reduce or eliminate this potential. Exterior berm slopes and interior slopes above the maximum water surface should be graded to a finished inclination no steeper than 2:1. Finished slope faces should be thoroughly compacted and vegetated to guard against erosion. We should review the stormwater plans when they are completed and revise our recommendations, if required. 4.8 Infiltration Feasibility Based on our study, subsurface conditions are generally not favorable for infiltration of site stormwater. The relatively shallow unweathered glacial till soils observed at the site contain a high percentage of soil fines that would impede any downward migration of site stormwater. Even low impact development (LID) techniques would likely fill up and overtop during rain events and cause minor local flooding. While zones of sands and gravels were observed in Test Pits TP-12 and TP-26, these are small areas and would not have sufficient volume to sustain long term infiltration, also, the deeper soil data obtained in the borings show these sands are likely also underlain by impermeable glacial till soils. Based on these soil conditions, infiltration at the site is not feasible and the stormwater should be managed using a conventional system. 4.9 Drainage Surface Final exterior grades should promote free and positive drainage away from the site at all times. Water must not be allowed to pond or collect adjacent to foundations or within the immediate building areas. We recommend providing a positive drainage gradient away from the building perimeter. If this gradient cannot be provided, surface water should be collected adjacent to the structures and directed to appropriate storm facilities. January 28, 2022 Revised June 3, 2022 Project No. T-8562 Page No. 10 Subsurface We recommend installing perimeter foundation drains adjacent to shallow foundations. The drains can be laid to grade at an invert elevation equivalent to the bottom of footing grade. The drains can consist of four-inch diameter perforated PVC pipe enveloped in washed pea gravel-sized drainage aggregate. The aggregate should extend six inches above and to the sides of the pipe. Roof and foundation drains should be tightlined separately to the storm drains. All drains should be provided with cleanouts at easily accessible locations. 4.10 Utilities Utility pipes should be bedded and backfilled in accordance with American Public Works Association (APWA) or the local jurisdictional specifications. At a minimum, trench backfill should be placed and compacted as structural fill as described in Section 4.2 of this report. As noted, most native soils excavated on the site should be suitable for use as backfill material during dry weather conditions. However, if utility construction takes place during the wet winter months, it will likely be necessary to import suitable wet weather fill for utility trench backfilling. 4.11 Pavements Pavement subgrades should be prepared as described in the Section 4.2 of this report. Regardless of the degree of relative compaction achieved, the subgrade must be firm and relatively unyielding before paving. The subgrade should be proofrolled with heavy rubber-tired construction equipment such as a loaded 10-yard dump truck to verify this condition. The pavement design section is dependent upon the supporting capability of the subgrade soils and the traffic conditions to which it will be subjected. For residential access, with traffic consisting mainly of light passenger vehicles with only occasional heavy traffic, and with a stable subgrade prepared as recommended, we recommend the following pavement sections:  Two inches of Hot Mix Asphalt (HMA) over four inches of Crushed Rock Base (CRB)  Three and one-half inches of full depth HMA The paving materials used should conform to the Washington State Department of Transportation (WSDOT) specifications for half-inch class HMA and CRB. Long-term pavement performance will depend on surface drainage. A poorly drained pavement section will be subject to premature failure as a result of surface water infiltrating into the subgrade soils and reducing their supporting capability. For optimum pavement performance, we recommend surface drainage gradients of at least two percent. Some degree of longitudinal and transverse cracking of the pavement surface should be expected over time. Regular maintenance should be planned to seal cracks when they occur. January 28, 2022 Revised June 3, 2022 Project No. T-8562 Page No. 11 5.0 ADDITIONAL SERVICES Terra Associates, Inc. should review the final design drawings and specifications in order to verify earthwork and foundation recommendations have been properly interpreted and implemented in project design. We should also provide geotechnical service during construction to observe compliance with our design concepts, specifications, and recommendations. This will allow for design changes if subsurface conditions differ from those anticipated prior to the start of construction. 6.0 LIMITATIONS We prepared this report in accordance with generally accepted geotechnical engineering practices. No other warranty, expressed or implied, is made. This report is the copyrighted property of Terra Associates, Inc. and is intended for specific application to the Federal Way Assemblage project in Federal Way, Washington. This report is for the exclusive use of Pulte Homes of Washington, Inc., and their authorized representatives. The analyses and recommendations presented in this report are based on data obtained from the subsurface explorations completed onsite. Variations in soil conditions can occur, the nature and extent of which may not become evident until construction. If variations appear evident, Terra Associates, Inc. should be requested to reevaluate the recommendations in this report prior to proceeding with construction. © 2021 Microsoft Corporation © 2021 TomTom SITE Environmental Earth Sciences Terra Associates, Inc. Consultants in Geotechnical Engineering Geology and Figure 1 VICINITY MAP 0 2000 4000 APPROXIMATE SCALE IN FEET REFERENCE: https://www.bing.com/maps ACCESSED 6/1/22 Proj.No. T-8562 Date:JUNE 2022 FEDERAL WAY, WASHINGTON FEDERAL WAY ASSEMBLAGE TP-1B-1B-2B-3B-4TP-2TP-3TP-4TP-5TP-6TP-7TP-8TP-9TP-10TP-11TP-13TP-12TP-14TP-15TP-16TP-17TP-18TP-19TP-20TP-21TP-22TP-23TP-24TP-25TP-26TP-27TP-28TP-29TP-30REFERENCE:REFERENCE ONLY AND SHOULD NOT BE USED FORDESIGN OR CONSTRUCTION PURPOSES.DIMENSIONS ARE APPROXIMATE. IT IS INTENDED FORNOTE:THIS SITE PLAN IS SCHEMATIC. ALL LOCATIONS ANDConsultants in Geotechnical EngineeringTerraAssociates, Inc.Geology andEnvironmental Earth SciencesEXPLORATION LOCATION PLANFigure 2LEGEND:0200400APPROXIMATE SCALE IN FEETAPPROXIMATE BORING LOCATIONSITE PLAN PROVIDED BY ESM.APPROXIMATE TEST PIT LOCATIONProj.No. T-8562Date:JUNE 2022FEDERAL WAY, WASHINGTONFEDERAL WAY ASSEMBLAGE 12" COMPACTED STRUCTURAL FILL EXCAVATED SLOPE (SEE REPORT TEXT FOR APPROPRIATE INCLINATIONS) SLOPE TO DRAIN 12" MINIMUM 3/4" MINUS WASHED GRAVEL 3" BELOW PIPE 12" OVER PIPE 4" DIAMETER PERFORATED PVC PIPE SEE NOTE 6"(MIN.) NOT TO SCALE NOTE: MIRADRAIN G100N PREFABRICATED DRAINAGE PANELS OR SIMILAR PRODUCT CAN BE SUBSTITUTED FOR THE 12-INCH WIDE GRAVEL DRAIN BEHIND WALL. DRAINAGE PANELS SHOULD EXTEND A MINIMUM OF SIX INCHES INTO 12-INCH THICK DRAINAGE GRAVEL LAYER OVER PERFORATED DRAIN PIPE. Environmental Earth Sciences Terra Associates, Inc. Consultants in Geotechnical Engineering Geology and TYPICAL WALL DRAINAGE DETAIL Figure 3Proj.No. T-8562 Date:JUNE 2022 FEDERAL WAY, WASHINGTON FEDERAL WAY ASSEMBLAGE Project No. T-8562 APPENDIX A FIELD EXPLORATION AND LABORATORY TESTING Federal Way Assemblage Milton Road South and South 376th Street Federal Way, Washington On June 1, 2021, and June 4, 2021, we investigated subsurface conditions at the site by excavating 30 test pits with a track-mounted mini-excavator to depths of about 6 to 10 feet below existing grades. On June 7, 2021, we supplemented this data by observing soil conditions at 4 borings drilled to depths of about 15 feet below existing surface grades. The test pit and boring locations were approximately determined in the field by sighting and pacing from existing surface features. The approximate test pit and test boring locations are shown on Figure 2. The Test Pit and Test Boring Logs are presented as Figures A-2 through A-35. A geotechnical engineer from our office conducted the field exploration. Our representative classified the soil conditions encountered, maintained a log of each test pit and test boring, obtained representative soil samples, and recorded water levels observed during excavation. During drilling, soil samples were obtained in general accordance with ASTM Test Designation D-1586. Using this procedure, a 2-inch (outside diameter) split barrel sampler is driven into the ground 18 inches using a 140-pound hammer free falling from a height of 30 inches. The number of blows required to drive the sampler 12 inches after an initial 6-inch set is referred to as the Standard Penetration Resistance value or N value. This is an index related to the consistency of cohesive soils and relative density of cohesionless materials. N values obtained for each sampling interval are recorded on the Test Boring Logs, Figures A-32 through A-35. All soil samples were visually classified in accordance with the Unified Soil Classification System (USCS) described on Figure A-1. Representative soil samples obtained from the test pits and test borings were placed in sealed plastic bags and taken to our laboratory for further examination and testing. The moisture content of each sample was measured and is reported on the Test Pit and Test Boring Logs. Grain size analyses were performed on select soil samples. The results are shown on Figure A-36. Environmental Earth Sciences Terra Associates, Inc. Consultants in Geotechnical Engineering Geology and MAJOR DIVISIONS LETTER SYMBOL TYPICAL DESCRIPTION GRAVELS More than 50% of coarse fraction is larger than No. 4 sieve Clean Gravels (less than 5% fines) GW Well-graded gravels, gravel-sand mixtures, little or no fines. GP Poorly-graded gravels, gravel-sand mixtures, little or no fines. Gravels with fines GM Silty gravels, gravel-sand-silt mixtures, non-plastic fines. GC Clayey gravels, gravel-sand-clay mixtures, plastic fines. SANDS More than 50% of coarse fraction is smaller than No. 4 sieve Clean Sands (less than 5% fines) SW Well-graded sands, sands with gravel, little or no fines. SP Poorly-graded sands, sands with gravel, little or no fines. Sands with fines SM Silty sands, sand-silt mixtures, non-plastic fines. SC Clayey sands, sand-clay mixtures, plastic fines. SILTS AND CLAYS Liquid Limit is less than 50% ML Inorganic silts, rock flour, clayey silts with slight plasticity. CL Inorganic clays of low to medium plasticity. (Lean clay) OL Organic silts and organic clays of low plasticity. SILTS AND CLAYS Liquid Limit is greater than 50% MH Inorganic silts, elastic. CH Inorganic clays of high plasticity. (Fat clay) OH Organic clays of high plasticity. HIGHLY ORGANIC SOILS PT Peat.COARSE GRAINED SOILSMore than 50% material largerthan No. 200 sieve sizeFINE GRAINED SOILSMore than 50% material smallerthan No. 200 sieve sizeDEFINITION OF TERMS AND SYMBOLS COHESIONLESSCOHESIVE Standard Penetration Density Resistance in Blows/Foot Very Loose 0-4 Loose 4-10 Medium Dense 10-30 Dense 30-50 Very Dense >50 Standard Penetration Consistancy Resistance in Blows/Foot Very Soft 0-2 Soft 2-4 Medium Stiff 4-8 Stiff 8-16 Very Stiff 16-32 Hard >32 2" OUTSIDE DIAMETER SPILT SPOON SAMPLER 2.4" INSIDE DIAMETER RING SAMPLER OR SHELBY TUBE SAMPLER WATER LEVEL (Date) Tr TORVANE READINGS, tsf Pp PENETROMETER READING, tsf DD DRY DENSITY, pounds per cubic foot LL LIQUID LIMIT, percent PI PLASTIC INDEX N STANDARD PENETRATION, blows per foot UNIFIED SOIL CLASSIFICATION SYSTEM Figure A-1Proj.No. T-8562 Date:JUNE 2022 FEDERAL WAY, WASHINGTON FEDERAL WAY ASSEMBLAGE Sample No.Depth (ft)PROJECT NAME: PROJ. NO: LOGGED BY: LOCATION: DATE LOGGED: APPROX. ELEV: DEPTH TO CAVING: FIGURE DEPTH TO GROUNDWATER: SURFACE CONDITIONS: Description Consistency/ Relative Density W (%)interpreted as being indicative of other locations at the site. NOTE: This subsurface information pertains only to this test pit location and should not be 0 1 2 3 4 5 6 7 8 9 10 A-2 T-8562 MJX Federal Way, Washington Grass Lawn June 1, 2021 Federal Way Assemblage LOG OF TEST PIT NO. TP-1 NA NA NA 22.0 9.7 8.7 9.3 very stiff dense (4-inches organic TOPSOIL) Gray SILT, dry, mottled, scattered rootlets. (ML) Gray silty SAND with gravel, fine to coarse sand, fine to coarse gravel, moist, trace cobbles, weak to moderate cementation. (SM) Gray GRAVEL with silt and sand, fine to coarse sand, fine to coarse gravel, moist, trace cobbles. (GP-GM) Test Pit terminated at approximately 8 feet. No groundwater seepage observed. No caving observed. Sample No.Depth (ft)PROJECT NAME: PROJ. NO: LOGGED BY: LOCATION: DATE LOGGED: APPROX. ELEV: DEPTH TO CAVING: FIGURE DEPTH TO GROUNDWATER: SURFACE CONDITIONS: Description Consistency/ Relative Density W (%)interpreted as being indicative of other locations at the site. NOTE: This subsurface information pertains only to this test pit location and should not be 0 1 2 3 4 5 6 7 8 9 10 A-3 T-8562 MJX Federal Way, Washington Grass Lawn June 1, 2021 Federal Way Assemblage LOG OF TEST PIT NO. TP-2 NA NA NA 15.5 16.3 11.2 12.7 16.7 very stiff dense (7-inches organic TOPSOIL) Gray SILT, dry, scattered rootlets, weak cementation. (ML) Brown silty SAND with gravel, fine to coarse sand, fine to coarse gravel, moist, scattered cobbles. (SM) Gray silty SAND with gravel, fine to coarse sand, fine to coarse gravel, moist, scattered cobbles. (SM) *fine sand observed below 7 feet. Test Pit terminated at approximately 8 feet. No groundwater seepage observed. No caving observed. Sample No.Depth (ft)PROJECT NAME: PROJ. NO: LOGGED BY: LOCATION: DATE LOGGED: APPROX. ELEV: DEPTH TO CAVING: FIGURE DEPTH TO GROUNDWATER: SURFACE CONDITIONS: Description Consistency/ Relative Density W (%)interpreted as being indicative of other locations at the site. NOTE: This subsurface information pertains only to this test pit location and should not be 0 1 2 3 4 5 6 7 8 9 10 A-4 T-8562 MJX Federal Way, Washington Grass June 1, 2021 Federal Way Assemblage LOG OF TEST PIT NO. TP-3 NA NA NA 6.3 14.0 11.0 9.2 medium dense dense (6-inches organic TOPSOIL) Brownish-gray silty SAND with gravel, fine to coarse sand, fine to coarse gravel, dry, moist below approx. 4 feet, scattered cobbles, trace rootlets. (SM) Gray silty SAND with gravel, fine to coarse sand, fine to coarse gravel, moist, slightly mottled, trace cobbles, weak to moderate cementation. (SM) Test Pit terminated at approximately 8 feet. No groundwater seepage observed. No caving observed. Sample No.Depth (ft)PROJECT NAME: PROJ. NO: LOGGED BY: LOCATION: DATE LOGGED: APPROX. ELEV: DEPTH TO CAVING: FIGURE DEPTH TO GROUNDWATER: SURFACE CONDITIONS: Description Consistency/ Relative Density W (%)interpreted as being indicative of other locations at the site. NOTE: This subsurface information pertains only to this test pit location and should not be 0 1 2 3 4 5 6 7 8 9 A-5 T-8562 MJX Federal Way, Washington Blackberries June 1, 2021 Federal Way Assemblage LOG OF TEST PIT NO. TP-4 NA NA NA 33.9 6.5 5.5 8.5 loose to medium dense medium dense dense (TOPSOIL) Black silty SAND, fine sand, moist, numerous rootlets, trace organics. (SM) Brownish-gray silty SAND with gravel, fine to medium sand, fine to coarse gravel, moist, trace cobbles, weak cementation. (SM) Gray silty SAND with gravel, fine to coarse sand, fine to coarse gravel, moist, trace cobbles, weak cementation. (SM) Test Pit terminated at approximately 7 feet. No groundwater seepage observed. No caving observed. Sample No.Depth (ft)PROJECT NAME: PROJ. NO: LOGGED BY: LOCATION: DATE LOGGED: APPROX. ELEV: DEPTH TO CAVING: FIGURE DEPTH TO GROUNDWATER: SURFACE CONDITIONS: Description Consistency/ Relative Density W (%)interpreted as being indicative of other locations at the site. NOTE: This subsurface information pertains only to this test pit location and should not be 0 1 2 3 4 5 6 7 8 9 A-6 T-8562 MJX Federal Way, Washington Grass June 1, 2021 Federal Way Assemblage LOG OF TEST PIT NO. TP-5 NA NA NA 6.6 6.9 11.4 medium dense dense (8-inches organic TOPSOIL) Brownish-gray silty SAND with gravel, fine to medium sand, fine to coarse gravel, dry, trace cobbles, occasional rootlet. (SM) Gray silty SAND with gravel, fine to coarse sand, fine to coarse gravel, moist, scattered cobbles, weak cementation. (SM) Test Pit terminated at approximately 7 feet. No groundwater seepage observed. No caving observed. Sample No.Depth (ft)PROJECT NAME: PROJ. NO: LOGGED BY: LOCATION: DATE LOGGED: APPROX. ELEV: DEPTH TO CAVING: FIGURE DEPTH TO GROUNDWATER: SURFACE CONDITIONS: Description Consistency/ Relative Density W (%)interpreted as being indicative of other locations at the site. NOTE: This subsurface information pertains only to this test pit location and should not be 0 1 2 3 4 5 6 7 8 9 A-7 T-8562 MJX Federal Way, Washington Tall Grass & Shrubs June 1, 2021 Federal Way Assemblage LOG OF TEST PIT NO. TP-6 NA NA NA 9.1 7.0 8.3 medium dense dense (8-inches organic TOPSOIL) Brownish-gray silty SAND with gravel, fine to medium sand, fine to coarse gravel, dry, trace cobbles, occasional rootlet. (SM) Gray silty SAND with gravel, fine to coarse sand, fine to coarse gravel, moist, trace cobbles, weak cementation. (SM) Test Pit terminated at approximately 7 feet. No groundwater seepage observed. No caving observed. Sample No.Depth (ft)PROJECT NAME: PROJ. NO: LOGGED BY: LOCATION: DATE LOGGED: APPROX. ELEV: DEPTH TO CAVING: FIGURE DEPTH TO GROUNDWATER: SURFACE CONDITIONS: Description Consistency/ Relative Density W (%)interpreted as being indicative of other locations at the site. NOTE: This subsurface information pertains only to this test pit location and should not be 0 1 2 3 4 5 6 7 8 A-8 T-8562 MJX Federal Way, Washington Blackberries June 1, 2021 Federal Way Assemblage LOG OF TEST PIT NO. TP-7 NA NA NA 13.8 10.1 13.2 medium dense dense to very dense Brownish-gray silty SAND with gravel, fine to medium sand, fine to coarse gravel, dry, scattered rootlets, trace cobbles. (SM) Gray silty SAND with gravel, fine to coarse sand, fine to coarse gravel, moist, trace cobbles, occasional boulder, weak to moderate cementation. (SM) Test Pit terminated at approximately 6 feet. No groundwater seepage observed. No caving observed. Sample No.Depth (ft)PROJECT NAME: PROJ. NO: LOGGED BY: LOCATION: DATE LOGGED: APPROX. ELEV: DEPTH TO CAVING: FIGURE DEPTH TO GROUNDWATER: SURFACE CONDITIONS: Description Consistency/ Relative Density W (%)interpreted as being indicative of other locations at the site. NOTE: This subsurface information pertains only to this test pit location and should not be 0 1 2 3 4 5 6 7 8 A-9 T-8562 MJX Federal Way, Washington Grass June 1, 2021 Federal Way Assemblage LOG OF TEST PIT NO. TP-8 NA NA NA 18.0 9.4 8.2 medium dense dense (5-inches organic TOPSOIL) Brownish-gray silty SAND with gravel, fine to medium sand, fine to coarse gravel, dry, scattered rootlets, trace cobbles, weak cementation. (SM) Gray silty SAND with gravel, fine to coarse sand, fine to coarse gravel, moist, trace cobbles, weak cementation. (SM) Test Pit terminated at approximately 6 feet. No groundwater seepage observed. No caving observed. Sample No.Depth (ft)PROJECT NAME: PROJ. NO: LOGGED BY: LOCATION: DATE LOGGED: APPROX. ELEV: DEPTH TO CAVING: FIGURE DEPTH TO GROUNDWATER: SURFACE CONDITIONS: Description Consistency/ Relative Density W (%)interpreted as being indicative of other locations at the site. NOTE: This subsurface information pertains only to this test pit location and should not be 0 1 2 3 4 5 6 7 8 A-10 T-8562 MJX Federal Way, Washington Blackberries June 1, 2021 Federal Way Assemblage LOG OF TEST PIT NO. TP-9 NA NA NA 16.0 7.6 8.2 medium dense dense to very dense (7-inches organic TOPSOIL) Brown silty SAND with gravel, fine to medium sand, fine to coarse gravel, moist, scattered rootlets, trace cobbles. (SM) Gray silty SAND with gravel, fine to coarse sand, fine to coarse gravel, trace cobbles, weak to moderate cementation. (SM) Test Pit terminated at approximately 6 feet. No groundwater seepage observed. No caving observed. Sample No.Depth (ft)PROJECT NAME: PROJ. NO: LOGGED BY: LOCATION: DATE LOGGED: APPROX. ELEV: DEPTH TO CAVING: FIGURE DEPTH TO GROUNDWATER: SURFACE CONDITIONS: Description Consistency/ Relative Density W (%)interpreted as being indicative of other locations at the site. NOTE: This subsurface information pertains only to this test pit location and should not be 0 1 2 3 4 5 6 7 8 A-11 T-8562 MJX Federal Way, Washington Blackberries June 1, 2021 Federal Way Assemblage LOG OF TEST PIT NO. TP-10 NA NA NA 15.5 9.3 9.3 medium dense dense (8-inches organic TOPSOIL) Brownish-gray silty SAND with gravel, fine to medium sand, fine to coarse gravel, dry to moist, trace rootlets, trace cobbles. (SM) Gray silty SAND with gravel, fine to coarse sand, fine to coarse gravel, moist, trace cobbles, weak to moderate cementation. (SM) Test Pit terminated at approximately 6 feet. No groundwater seepage observed. No caving observed. Sample No.Depth (ft)PROJECT NAME: PROJ. NO: LOGGED BY: LOCATION: DATE LOGGED: APPROX. ELEV: DEPTH TO CAVING: FIGURE DEPTH TO GROUNDWATER: SURFACE CONDITIONS: Description Consistency/ Relative Density W (%)interpreted as being indicative of other locations at the site. NOTE: This subsurface information pertains only to this test pit location and should not be 0 1 2 3 4 5 6 7 8 9 A-12 T-8562 MJX Federal Way, Washington Grass June 1, 2021 Federal Way Assemblage LOG OF TEST PIT NO. TP-11 NA NA NA 15.1 9.9 10.4 very stiff dense (6-inches organic TOPSOIL) Brownish-gray sandy SILT with gravel, fine medium sand, fine to coarse gravel, dry, trace rootlets, trace cobbles, weak cementation. (ML) Gray silty SAND with gravel, fine to coarse sand, fine to coarse gravel, moist, trace cobbles, occasional boulder. (SM) Test Pit terminated at approximately 7 feet. No groundwater seepage observed. No caving observed. Sample No.Depth (ft)PROJECT NAME: PROJ. NO: LOGGED BY: LOCATION: DATE LOGGED: APPROX. ELEV: DEPTH TO CAVING: FIGURE DEPTH TO GROUNDWATER: SURFACE CONDITIONS: Description Consistency/ Relative Density W (%)interpreted as being indicative of other locations at the site. NOTE: This subsurface information pertains only to this test pit location and should not be 0 1 2 3 4 5 6 7 8 9 10 11 A-13 T-8562 MJX Federal Way, Washington Grass June 1, 2021 Federal Way Assemblage LOG OF TEST PIT NO. TP-12 NA NA 1 to 3 ft 5.5 4.0 2.4 medium dense to dense (9-inches organic TOPSOIL) Brown to gray SAND with gravel to GRAVEL with sand, fine to coarse sand, fine to coarse gravel, moist, scattered cobbles, trace silt. (SP/GP) Test Pit terminated at approximately 9 feet. No groundwater seepage observed. Minor caving observed from approximately 1 to 3 feet. Sample No.Depth (ft)PROJECT NAME: PROJ. NO: LOGGED BY: LOCATION: DATE LOGGED: APPROX. ELEV: DEPTH TO CAVING: FIGURE DEPTH TO GROUNDWATER: SURFACE CONDITIONS: Description Consistency/ Relative Density W (%)interpreted as being indicative of other locations at the site. NOTE: This subsurface information pertains only to this test pit location and should not be 0 1 2 3 4 5 6 7 8 9 A-14 T-8562 MJX Federal Way, Washington Grass June 1, 2021 Federal Way Assemblage LOG OF TEST PIT NO. TP-13 NA NA NA 23.2 10.7 7.1 9.1 very stiff medium dense dense (7-inches organic TOPSOIL) Gray SILT, dry, trace rootlets, weak cementation. (ML) Brownish-gray silty SAND with gravel, fine to coarse sand, fine to coarse gravel, moist, trace cobbles. (SM) Gray silty SAND with gravel, fine to coarse sand, fine to coarse gravel, moist, slighlty mottled, trace cobbles, weak cementation. (SM) Test Pit terminated at approximately 7 feet. No groundwater seepage observed. No caving observed. Sample No.Depth (ft)PROJECT NAME: PROJ. NO: LOGGED BY: LOCATION: DATE LOGGED: APPROX. ELEV: DEPTH TO CAVING: FIGURE DEPTH TO GROUNDWATER: SURFACE CONDITIONS: Description Consistency/ Relative Density W (%)interpreted as being indicative of other locations at the site. NOTE: This subsurface information pertains only to this test pit location and should not be 0 1 2 3 4 5 6 7 8 9 A-15 T-8562 MJX Federal Way, Washington Grass June 1, 2021 Federal Way Assemblage LOG OF TEST PIT NO. TP-14 NA NA NA 9.9 12.1 8.8 medium dense dense (7-inches organic TOPSOIL) Brownish-gray silty SAND with gravel, fine to medium sand, fine to coarse gravel, dry, trace rootlets, trace cobbles. (SM) Brownish-gray to gray silty SAND with gravel, fine to coarse sand, fine to coarse gravel, moist, trace cobbles, occasional boulder, weak cementation. (SM) Test Pit terminated at approximately 7 feet. No groundwater seepage observed. No caving observed. Sample No.Depth (ft)PROJECT NAME: PROJ. NO: LOGGED BY: LOCATION: DATE LOGGED: APPROX. ELEV: DEPTH TO CAVING: FIGURE DEPTH TO GROUNDWATER: SURFACE CONDITIONS: Description Consistency/ Relative Density W (%)interpreted as being indicative of other locations at the site. NOTE: This subsurface information pertains only to this test pit location and should not be 0 1 2 3 4 5 6 7 8 9 10 A-16 T-8562 MJX Federal Way, Washington Duff & Shrubs June 1, 2021 Federal Way Assemblage LOG OF TEST PIT NO. TP-15 NA NA 3 to 7 ft 21.0 4.8 6.7 very stiff dense (9-inches organic TOPSOIL) Gray SILT, dry, trace rootlets, weak cementation. (ML) Brownish-gray SAND with silt and gravel to silty SAND with gravel, fine to coarse sand, fine to coarse gravel, moist, scattered cobbles. (SP-SM/SM) Gray silty SAND with gravel, fine to coarse sand, fine to coarse gravel, moist, trace cobbles, weak cementation. (SM) Test Pit terminated at approximately 8 feet. No groundwater seepage observed. Minor caving observed from approximately 3 to 7 feet. Sample No.Depth (ft)PROJECT NAME: PROJ. NO: LOGGED BY: LOCATION: DATE LOGGED: APPROX. ELEV: DEPTH TO CAVING: FIGURE DEPTH TO GROUNDWATER: SURFACE CONDITIONS: Description Consistency/ Relative Density W (%)interpreted as being indicative of other locations at the site. NOTE: This subsurface information pertains only to this test pit location and should not be 0 1 2 3 4 5 6 7 8 9 A-17 T-8562 MJX Federal Way, Washington Grass Lawn June 1, 2021 Federal Way Assemblage LOG OF TEST PIT NO. TP-16 NA NA NA 10.5 18.2 8.7 medium dense dense (7-inches organic TOPSOIL) Brownish-gray silty SAND with gravel, fine to medium sand, fine to coarse gravel, dry, trace rootlets, trace cobbles. (SM) Gray silty SAND with gravel, fine to coarse sand, fine to coarse gravel, moist, some mottling, trace cobbles, occasional boulder, weak cementation. (SM) Test Pit terminated at approximately 7 feet. No groundwater seepage observed. No caving observed. Sample No.Depth (ft)PROJECT NAME: PROJ. NO: LOGGED BY: LOCATION: DATE LOGGED: APPROX. ELEV: DEPTH TO CAVING: FIGURE DEPTH TO GROUNDWATER: SURFACE CONDITIONS: Description Consistency/ Relative Density W (%)interpreted as being indicative of other locations at the site. NOTE: This subsurface information pertains only to this test pit location and should not be 0 1 2 3 4 5 6 7 8 9 10 11 A-18 T-8562 MJX Federal Way, Washington Grass & Shrubs June 1, 2021 Federal Way Assemblage LOG OF TEST PIT NO. TP-17 NA NA NA 20.7 37.4 8.0 6.9 very stiff dense (7-inches organic TOPSOIL) Gray SILT with gravel, fine to coarse gravel, dry to moist, trace rootlets, weak cementation. (ML) Gray silty SAND with gravel, fine to coarse sand, fine to coarse gravel, moist, trace cobbles, weak cementation. (SM) Test Pit terminated at approximately 9 feet. No groundwater seepage observed. No caving observed. Sample No.Depth (ft)PROJECT NAME: PROJ. NO: LOGGED BY: LOCATION: DATE LOGGED: APPROX. ELEV: DEPTH TO CAVING: FIGURE DEPTH TO GROUNDWATER: SURFACE CONDITIONS: Description Consistency/ Relative Density W (%)interpreted as being indicative of other locations at the site. NOTE: This subsurface information pertains only to this test pit location and should not be 0 1 2 3 4 5 6 7 8 A-19 T-8562 MJX Federal Way, Washington Understory June 4, 2021 Federal Way Assemblage LOG OF TEST PIT NO. TP-18 NA NA NA 13.2 13.0 8.4 stiff dense very dense (5-inches organic TOPSOIL) Brownish-gray SILT, dry, trace rootlets, weak cementation. (ML) Gray silty SAND with gravel, fine to coarse sand, fine to coarse gravel, moist, slightly mottled, trace cobbles, weak to moderate cementation. (SM) Test Pit terminated at approximately 6 feet. No groundwater seepage observed. No caving observed. Sample No.Depth (ft)PROJECT NAME: PROJ. NO: LOGGED BY: LOCATION: DATE LOGGED: APPROX. ELEV: DEPTH TO CAVING: FIGURE DEPTH TO GROUNDWATER: SURFACE CONDITIONS: Description Consistency/ Relative Density W (%)interpreted as being indicative of other locations at the site. NOTE: This subsurface information pertains only to this test pit location and should not be 0 1 2 3 4 5 6 7 8 A-20 T-8562 MJX Federal Way, Washington Understory June 4, 2021 Federal Way Assemblage LOG OF TEST PIT NO. TP-19 NA NA NA 7.7 8.8 6.3 medium dense dense very dense (5-inches organic TOPSOIL) Brown silty SAND with gravel, fine to medium sand, fine to coarse gravel, dry to moist, occasional rootlet. (SM) Gray silty SAND with gravel, fine to coarse sand, fine to coarse gravel, dry to moist, trace cobbles, moderate cementation. (SM) Test Pit terminated at approximately 6 feet. No groundwater seepage observed. No caving observed. Sample No.Depth (ft)PROJECT NAME: PROJ. NO: LOGGED BY: LOCATION: DATE LOGGED: APPROX. ELEV: DEPTH TO CAVING: FIGURE DEPTH TO GROUNDWATER: SURFACE CONDITIONS: Description Consistency/ Relative Density W (%)interpreted as being indicative of other locations at the site. NOTE: This subsurface information pertains only to this test pit location and should not be 0 1 2 3 4 5 6 7 8 A-21 T-8562 MJX Federal Way, Washington Understory June 4, 2021 Federal Way Assemblage LOG OF TEST PIT NO. TP-20 NA NA NA 19.6 6.3 8.0 stiff dense very dense (5-inches organic TOPSOIL) Brownish-gray SILT, dry, trace rootlets, weak cementation. (ML) Gray silty SAND with gravel, fine to coarse sand, fine to coarse gravel, moist, trace cobbles, weak to moderate cementation. (SM) Test Pit terminated at approximately 6 feet. No groundwater seepage observed. No caving observed. Sample No.Depth (ft)PROJECT NAME: PROJ. NO: LOGGED BY: LOCATION: DATE LOGGED: APPROX. ELEV: DEPTH TO CAVING: FIGURE DEPTH TO GROUNDWATER: SURFACE CONDITIONS: Description Consistency/ Relative Density W (%)interpreted as being indicative of other locations at the site. NOTE: This subsurface information pertains only to this test pit location and should not be 0 1 2 3 4 5 6 7 8 A-22 T-8562 MJX Federal Way, Washington Understory June 4, 2021 Federal Way Assemblage LOG OF TEST PIT NO. TP-21 NA NA NA 20.6 8.9 6.8 stiff dense very dense (5-inches organic TOPSOIL) Brownish-gray SILT, dry, occasional rootlet, weak cementation. (ML) Gray silty SAND with gravel, fine to coarse sand, fine to coarse gravel, moist, trace cobbles, moderate cementation. (SM) Test Pit terminated at approximately 6 feet. No groundwater seepage observed. No caving observed. Sample No.Depth (ft)PROJECT NAME: PROJ. NO: LOGGED BY: LOCATION: DATE LOGGED: APPROX. ELEV: DEPTH TO CAVING: FIGURE DEPTH TO GROUNDWATER: SURFACE CONDITIONS: Description Consistency/ Relative Density W (%)interpreted as being indicative of other locations at the site. NOTE: This subsurface information pertains only to this test pit location and should not be 0 1 2 3 4 5 6 7 8 A-23 T-8562 MJX Federal Way, Washington Understory June 4, 2021 Federal Way Assemblage LOG OF TEST PIT NO. TP-22 NA NA NA 14.1 11.2 8.4 stiff dense very dense (10-inches organic TOPSOIL) Brownish-gray SILT with gravel, fine to coarse gravel, dry, mottled, scattered rootlets. (ML) Gray silty SAND with gravel, fine to coarse sand, fine to coarse gravel, moist, scattered cobbles, weak cementation. (SM) Test Pit terminated at approximately 6 feet. No groundwater seepage observed. No caving observed. Sample No.Depth (ft)PROJECT NAME: PROJ. NO: LOGGED BY: LOCATION: DATE LOGGED: APPROX. ELEV: DEPTH TO CAVING: FIGURE DEPTH TO GROUNDWATER: SURFACE CONDITIONS: Description Consistency/ Relative Density W (%)interpreted as being indicative of other locations at the site. NOTE: This subsurface information pertains only to this test pit location and should not be 0 1 2 3 4 5 6 7 8 A-24 T-8562 MJX Federal Way, Washington Understory June 4, 2021 Federal Way Assemblage LOG OF TEST PIT NO. TP-23 NA NA NA 27.8 16.3 7.5 7.2 stiff dense very dense (3-inches organic TOPSOIL) Brownish-gray SILT with gravel, fine to coarse gravel, dry to moist, mottled, trace rootlets, weak cementation. (ML) Gray silty SAND with gravel, fine to coarse sand, fine to coarse gravel, moist, trace cobbles, weak to moderate cementation. (SM) Test Pit terminated at approximately 6 feet. No groundwater seepage observed. No caving observed. Sample No.Depth (ft)PROJECT NAME: PROJ. NO: LOGGED BY: LOCATION: DATE LOGGED: APPROX. ELEV: DEPTH TO CAVING: FIGURE DEPTH TO GROUNDWATER: SURFACE CONDITIONS: Description Consistency/ Relative Density W (%)interpreted as being indicative of other locations at the site. NOTE: This subsurface information pertains only to this test pit location and should not be 0 1 2 3 4 5 6 7 8 A-25 T-8562 MJX Federal Way, Washington Understory June 4, 2021 Federal Way Assemblage LOG OF TEST PIT NO. TP-24 NA NA NA 5.0 5.5 7.1 medium dense dense very dense (7-inches organic TOPSOIL) Brown silty SAND with gravel, fine to medium sand, fine to coarse gravel, dry, occasional cobbles. (SM) Gray silty SAND with gravel, fine to coarse sand, fine to coarse gravel, dry to moist, trace cobbles, weak cementation. (SM) Test Pit terminated at approximately 6 feet. No groundwater seepage observed. No caving observed. Sample No.Depth (ft)PROJECT NAME: PROJ. NO: LOGGED BY: LOCATION: DATE LOGGED: APPROX. ELEV: DEPTH TO CAVING: FIGURE DEPTH TO GROUNDWATER: SURFACE CONDITIONS: Description Consistency/ Relative Density W (%)interpreted as being indicative of other locations at the site. NOTE: This subsurface information pertains only to this test pit location and should not be 0 1 2 3 4 5 6 7 8 A-26 T-8562 MJX Federal Way, Washington Understory June 4, 2021 Federal Way Assemblage LOG OF TEST PIT NO. TP-25 NA NA NA 7.5 4.4 6.8 medium dense dense very dense (7-inches organic TOPSOIL) Brown silty SAND with gravel, fine to medium sand, fine to coarse gravel, dry, trace rootlets, trace cobbles. (SM) Gray silty SAND with gravel, fine to coarse sand, fine to coarse gravel, dry, trace cobbles, moderate cementation. (SM) Test Pit terminated at approximately 6 feet. No groundwater seepage observed. No caving observed. Sample No.Depth (ft)PROJECT NAME: PROJ. NO: LOGGED BY: LOCATION: DATE LOGGED: APPROX. ELEV: DEPTH TO CAVING: FIGURE DEPTH TO GROUNDWATER: SURFACE CONDITIONS: Description Consistency/ Relative Density W (%)interpreted as being indicative of other locations at the site. NOTE: This subsurface information pertains only to this test pit location and should not be 0 1 2 3 4 5 6 7 8 9 10 11 12 A-27 T-8562 MJX Federal Way, Washington Understory June 4, 2021 Federal Way Assemblage LOG OF TEST PIT NO. TP-26 NA NA NA 9.7 5.0 4.6 medium dense dense (7-inches organic TOPSOIL) Brownish-gray to gray silty SAND with gravel, fine to coarse sand, fine to coarse gravel, dry, trace cobbles. (SM) Brownish-gray SAND with gravel, fine to coarse sand, fine to coarse gravel, dry to moist, trace silt, trace cobbles. (SP) Test Pit terminated at approximately 10 feet. No groundwater seepage observed. No caving observed. Sample No.Depth (ft)PROJECT NAME: PROJ. NO: LOGGED BY: LOCATION: DATE LOGGED: APPROX. ELEV: DEPTH TO CAVING: FIGURE DEPTH TO GROUNDWATER: SURFACE CONDITIONS: Description Consistency/ Relative Density W (%)interpreted as being indicative of other locations at the site. NOTE: This subsurface information pertains only to this test pit location and should not be 0 1 2 3 4 5 6 7 8 A-28 T-8562 MJX Federal Way, Washington Understory June 4, 2021 Federal Way Assemblage LOG OF TEST PIT NO. TP-27 NA NA NA 20.7 6.9 6.5 stiff dense (5-inches organic TOPSOIL) Gray SILT, dry, mottled, trace rootlets, weak cementation. (ML) Gray silty SAND with gravel, fine to coarse sand, fine to coarse gravel, moist, trace cobbles, weak cementation. (SM) Test Pit terminated at approximately 6 feet. No groundwater seepage observed. No caving observed. Sample No.Depth (ft)PROJECT NAME: PROJ. NO: LOGGED BY: LOCATION: DATE LOGGED: APPROX. ELEV: DEPTH TO CAVING: FIGURE DEPTH TO GROUNDWATER: SURFACE CONDITIONS: Description Consistency/ Relative Density W (%)interpreted as being indicative of other locations at the site. NOTE: This subsurface information pertains only to this test pit location and should not be 0 1 2 3 4 5 6 7 8 A-29 T-8562 MJX Federal Way, Washington Understory June 4, 2021 Federal Way Assemblage LOG OF TEST PIT NO. TP-28 NA NA NA 30.9 6.2 5.6 stiff dense very dense (10-inches organic TOPSOIL) Gray SILT, dry, mottled, trace rootlets, weak cementation. (ML) Gray silty SAND with gravel, fine to coarse sand, fine to coarse gravel, moist, trace cobbles, weak to moderate cementation. (SM) Test Pit terminated at approximately 6 feet. No groundwater seepage observed. No caving observed. Sample No.Depth (ft)PROJECT NAME: PROJ. NO: LOGGED BY: LOCATION: DATE LOGGED: APPROX. ELEV: DEPTH TO CAVING: FIGURE DEPTH TO GROUNDWATER: SURFACE CONDITIONS: Description Consistency/ Relative Density W (%)interpreted as being indicative of other locations at the site. NOTE: This subsurface information pertains only to this test pit location and should not be 0 1 2 3 4 5 6 7 8 A-30 T-8562 MJX Federal Way, Washington Understory June 4, 2021 Federal Way Assemblage LOG OF TEST PIT NO. TP-29 NA NA NA 22.9 11.1 7.7 stiff dense very dense (6-inches organic TOPSOIL) Gray SILT, dry, mottled, trace rootlets, weak cementation. (ML) Gray silty SAND with gravel, fine to coarse sand, fine to coarse gravel, dry to moist, trace cobbles, weak to moderate cementation. (SM) Test Pit terminated at approximately 6 feet. No groundwater seepage observed. No caving observed. Sample No.Depth (ft)PROJECT NAME: PROJ. NO: LOGGED BY: LOCATION: DATE LOGGED: APPROX. ELEV: DEPTH TO CAVING: FIGURE DEPTH TO GROUNDWATER: SURFACE CONDITIONS: Description Consistency/ Relative Density W (%)interpreted as being indicative of other locations at the site. NOTE: This subsurface information pertains only to this test pit location and should not be 0 1 2 3 4 5 6 7 8 A-31 T-8562 MJX Federal Way, Washington Understory June 4, 2021 Federal Way Assemblage LOG OF TEST PIT NO. TP-30 NA NA NA 16.9 5.8 8.5 stiff dense very dense (7-inches organic TOPSOIL) Brownish-gray SILT, dry, mottled, occasional rootlet, weak cementation. (ML) Gray silty SAND with gravel, fine to coarse sand, fine to coarse gravel, dry to moist, trace cobbles, weak to moderate cementation. (SM) Test Pit terminated at approximately 6 feet. No groundwater seepage observed. No caving observed. Figure No. Project:Project No: Driller:Client: Location:Depth to Groundwater: Logged By: Approx. Elev: Date Drilled:Depth (ft)Sample IntervalMoisture Content (%) 10 30 50 Blows / foot SPT (N)Consistency/ Relative DensitySoil Description pertains only to this boring location and should not be interpeted as being indicative of NOTE: This borehole log has been prepared for geotechnical purposes. This information other areas of the site 0 5 10 15 20 A-32LOG OF BORING NO. B-1 Federal Way Assemblage T-8562 BoreTecPulte Homes of Washington, Inc. NAFederal Way, Washington MJX NA June 7, 2021 1.6 3.2 3.2 4.4 6.2 29 39 38 42 94/11" 50/5" medium dense dense very dense Brown GRAVEL with sand, fine to coarse sand, fine to coarse gravel, moist, numerous cobbles. (GP) *No retrievable sample due to sampler bouncing on cobble* Gray GRAVEL with silt and sand, fine to coarse sand, fine to coarse gravel, dry. (GP-GM) Brown to gray SAND with gravel, fine to coarse sand, fine to coarse gravel, moist, trace silt, occasional silty SAND seam. (SP) Gray silty SAND with gravel, fine to coarse sand, fine to coarse gravel, moist. (SM) Test Boring terminated at approximately 15 feet. No groundwater seepage observed. Figure No. Project:Project No: Driller:Client: Location:Depth to Groundwater: Logged By: Approx. Elev: Date Drilled:Depth (ft)Sample IntervalMoisture Content (%) 10 30 50 Blows / foot SPT (N)Consistency/ Relative DensitySoil Description pertains only to this boring location and should not be interpeted as being indicative of NOTE: This borehole log has been prepared for geotechnical purposes. This information other areas of the site 0 5 10 15 20 A-33LOG OF BORING NO. B-2 Federal Way Assemblage T-8562 BoreTecPulte Homes of Washington, Inc. 10 ftFederal Way, Washington MJX NA June 7, 2021 2.9 1.5 6.3 11.0 12.4 8.1 12 62 50/5" 50/6" 50/3" 63/10" medium dense very dense Brown SAND with silt and gravel, fine to coarse sand, fine to coarse gravel, dry, occasional rootlet. (SP-SM) Gray silty SAND with gravel, fine to coarse sand, fine to coarse gravel, dry to wet. (SM) *Water perched around gravel observed* Gray SAND with silt to silty SAND, fine to medium sand, moist. (SP-SM/SM) Gray silty SAND with gravel, fine to coarse sand, fine to coarse gravel, moist. (SM) Test Boring terminated at approximately 15 feet. Light perched groundwater seepage observed at approximately 10 feet. Figure No. Project:Project No: Driller:Client: Location:Depth to Groundwater: Logged By: Approx. Elev: Date Drilled:Depth (ft)Sample IntervalMoisture Content (%) 10 30 50 Blows / foot SPT (N)Consistency/ Relative DensitySoil Description pertains only to this boring location and should not be interpeted as being indicative of NOTE: This borehole log has been prepared for geotechnical purposes. This information other areas of the site 0 5 10 15 20 A-34LOG OF BORING NO. B-3 Federal Way Assemblage T-8562 BoreTecPulte Homes of Washington, Inc. 10 ftFederal Way, Washington MJX NA June 7, 2021 16.6 12.2 9.0 10.2 8.2 5.6 39 22 62 70 93 72 medium dense very dense Brown silty SAND with gravel, fine to coarse sand, fine to coarse gravel, dry to moist, scattered rootlets, infrequent SAND seams. (SM) Gray silty SAND with gravel, fine to coarse sand, fine to coarse gravel, moist, slightly mottled, occasional SAND and SAND with silt seams. (SM) *12-inch inundated SAND with silt layer observed* *alternating SAND with gravel layers observed* Test Boring terminated at approximately 15 feet. Light perched groundwater seepage observed at approximately 10 feet. Figure No. Project:Project No: Driller:Client: Location:Depth to Groundwater: Logged By: Approx. Elev: Date Drilled:Depth (ft)Sample IntervalMoisture Content (%) 10 30 50 Blows / foot SPT (N)Consistency/ Relative DensitySoil Description pertains only to this boring location and should not be interpeted as being indicative of NOTE: This borehole log has been prepared for geotechnical purposes. This information other areas of the site 0 5 10 15 20 A-35LOG OF BORING NO. B-4 Federal Way Assemblage T-8562 BoreTecPulte Homes of Washington, Inc. NAFederal Way, Washington MJX NA June 7, 2021 28.3 16.1 21.2 9.4 8.3 10.8 17.0 17 18 54 50 95/11" 50/4" very stiff very dense Brownish-gray SILT, dry to moist, mottled, trace rootlets. (ML) Brown SILT to SILT with gravel, fine to coarse gravel, moist, interbedded SAND and SAND with silt seams. (ML) Gray silty SAND with gravel, fine to coarse sand, fine to coarse gravel, moist. (SM) Dark gray SAND with silt, fine to medium sand, moist. (SP- SM) Test Boring terminated at approximately 15 feet. No groundwater seepage observed. Tested By: FQ LL PL D85 D60 D50 D30 D15 D10 Cc Cu Material Description USCS AASHTO Project No.Client:Remarks: Project: Location: Test Pit TP-1 Depth: 6 ft Sample Number: 3 Location: Test Pit TP-12 Depth: 4 ft Sample Number: 2 Location: Test Pit TP-26 Depth: 3 ft Sample Number: 2 Terra Associates, Inc. Kirkland, WA Figure 24.7475 7.5294 3.8928 0.3715 0.1450 0.0808 0.23 93.17 14.5495 8.9085 6.3640 1.8114 0.4918 0.3562 1.03 25.01 14.7019 6.8316 3.9272 0.8787 0.3753 0.2759 0.41 24.76 GRAVEL with silt and sand GP-GM GRAVEL with sand GP SAND with gravel SP T-8562 Pulte Homes of Washington, Inc. A-36PERCENT FINER0 10 20 30 40 50 60 70 80 90 100 GRAIN SIZE - mm. 0.0010.010.1110100 % +3"Coarse % Gravel Fine Coarse Medium % Sand Fine Silt % Fines Clay 0.0 22.6 24.9 8.2 12.3 22.5 9.5 0.0 3.3 52.2 13.3 18.4 11.5 1.3 0.0 6.9 40.0 12.6 23.2 12.9 4.46 in.3 in.2 in.1½ in.1 in.¾ in.½ in.3/8 in.#4#10#20#30#40#60#100#140#200Particle Size Distribution Report Federal Way Assemblage Tested on June 15, 2021 Tested on June 15, 2021 Tested on June 15, 2021