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21-101296 -Geotechnical (Soils) Report-04-02-2021-V1associated earth sciences incorporated Associated Earth Sciences, Inc. 911 5th Avenue Kirkland, WA 98033 P (425) 827 7701 Subsurface Exploration, Geologic Hazard, Infiltration Feasibility, and Preliminary Geotechnical Engineering Report OLYMPIC VIEW K-8 SCHOOL Federal Way, Washington Prepared For: FEDERAL WAY SCHOOL DISTRICT NO. 210 Project No. 20200286E001 November 4, 2020 Kirkland | Tacoma | Mount Vernon 425-827-7701 | www.aesgeo.com November 4, 2020 Project No. 20200286E001 Federal Way School District No. 210 1211 South 332nd Street Federal Way, Washington 98003 Attention: Mr. Mike Kwaske Subject: Subsurface Exploration, Geologic Hazard, Infiltration Feasibility, and Preliminary Geotechnical Engineering Report Olympic View K-8 School 2626 SW 327th Street Federal Way, Washington Dear Mr. Kwaske: We are pleased to present the enclosed copy of the referenced report. This report summarizes the results of tasks including subsurface exploration, geologic hazard analysis, infiltration feasibility assessment, and preliminary geotechnical engineering, and offers preliminary recommendations for design of the project. We have enjoyed working with you on this study and are confident that the preliminary recommendations presented in this report will aid in the successful completion of your project. Please contact me if you have any questions or if we can be of additional help to you. Sincerely, ASSOCIATED EARTH SCIENCES, INC. Kirkland, Washington ______________________________ Kurt D. Merriman, P.E. Senior Principal Engineer KDM/ld - 20200286E001-2 SUBSURFACE EXPLORATION, GEOLOGIC HAZARD, INFILTRATION FEASIBILITY, AND PRELIMINARY GEOTECHNICAL ENGINEERING REPORT OLYMPIC VIEW K-8 SCHOOL Federal Way, Washington Prepared for: Federal Way School District No. 210 1211 South 332nd Street Federal Way, Washington 98003 Prepared by: Associated Earth Sciences, Inc. 911 5th Avenue Kirkland, Washington 98033 425-827-7701 November 4, 2020 Project No. 20200286E001 Subsurface Exploration, Geologic Hazard, Infiltration Feasibility, Olympic View K-8 School and Preliminary Geotechnical Engineering Report Federal Way, Washington Project and Site Conditions November 4, 2020 ASSOCIATED EARTH SCIENCES, INC. ART/ld - 20200286E001-2 Page 1 I. PROJECT AND SITE CONDITIONS 1.0 INTRODUCTION This report presents the results of Associated Earth Sciences, Inc.’s (AESI’s) subsurface exploration, geologic hazard analysis, preliminary geotechnical engineering, and stormwater infiltration feasibility study for the proposed demolition and replacement of the existing Olympic View K-8 School in Federal Way, Washington. Our recommendations are preliminary in that the project is in the early design phase. The site location is shown on the “Vicinity Map,” Figure 1. The approximate locations of explorations completed for this study are shown on the “Site and Exploration Plan,” Figure 2. A Light Detection and Ranging (LIDAR)-based site vicinity map is included as “LIDAR Vicinity Map” Figure 3. The location of the site in relation to groundwater supply wells is shown on the map of “Critical Aquifer Recharge Areas,” Figure 4. Interpretive exploration logs of subsurface explorations completed for this study and laboratory test data are included in Appendix A. 1.1 Purpose and Scope The purpose of this study is to provide subsurface soil and groundwater data to be utilized in the preliminary design of the Olympic View K-8 School replacement project. Our study included reviewing selected available geologic literature, advancing eight exploration borings (EB-1 through EB-8), installing one groundwater observation well, completing laboratory testing of soil grain-size distribution, and performing a geologic study of subsurface sediment and groundwater conditions. Geotechnical engineering studies were completed to determine the type of suitable foundations, allowable foundation soil bearing pressures, anticipated foundation settlements, erosion considerations, drainage considerations, and to provide infiltration feasibility recommendations. This report summarizes our current fieldwork and offers preliminary design recommendations based on our present understanding of the project. 1.2 Authorization Authorization to proceed with this study was given to AESI by means of District Purchase Order 21000138 dated September 1, 2020. Our study was accomplished in general accordance with our proposal, dated August 14, 2020. This report has been prepared for the exclusive use of Federal Way School District and its agents, for specific application to this project. Within the limitations of scope, schedule, and budget, our services have been performed in accordance with generally accepted geotechnical engineering and engineering geology practices in effect in this area at the time our report was prepared. No other warranty, express or implied, is made. Subsurface Exploration, Geologic Hazard, Infiltration Feasibility, Olympic View K-8 School and Preliminary Geotechnical Engineering Report Federal Way, Washington Project and Site Conditions November 4, 2020 ASSOCIATED EARTH SCIENCES, INC. ART/ld - 20200286E001-2 Page 2 2.0 PROJECT AND SITE DESCRIPTION The project site is that of the existing Olympic View K-8 School. The existing school was constructed in 1963. The existing school buildings are situated on the south-central part of the site, with paved parking areas to the east and south, paved and natural turf play areas to the north, and a bus drop-off lane to the south. Twin Lakes Golf and Country Club is adjacent offsite to the southwest. On-site topography is relatively flat where the existing buildings and playfields are located, with vertical relief of less than about 5 feet. At the north and southwest edges of the site, slopes descend from the developed portion of the site to the property boundary. In both locations existing slopes are up to about 15 feet tall. The existing slopes are not mapped as critical areas on the City of Federal Way Critical Areas Map dated May 2016. The slopes do not appear to meet the definition for Landslide Hazard Areas as defined in Federal Way Municipal Code (FWMC) Section 19.05.070 based on published aerial topographic survey data. At the time this preliminary report was written an on-site topographic survey had not been completed. The project will include demolition of the existing school and construction of a new K-8 school. At the time this report was prepared the design team was starting work and a project concept had not been selected. We anticipate that the new facility will be constructed close to existing grades without deep excavations or thick fill placement. Based on historical information discussed later in this report, and on subsurface data observed in our borings, the new building will likely be supported on conventional shallow foundations underlain by a ground improvement system consisting of aggregate piers. The project will likely include one or more stormwater infiltration facilities. 2.1 Historical Geotechnical Work AESI previously completed geotechnical engineering tasks for the District on the Olympic View Elementary School campus in 1998 and 2000. In 1998, we completed a limited investigation of an area of floor slab settlement and cracking. That study relied, in part, on a geotechnical report prepared in the 1960’s by another consultant during design of the school that now exists. The older geotechnical report was not retained in our 1998 project archives but was summarized in our 1998 report. The older geotechnical report concluded that the project site was underlain in 1960 by approximately 10 feet of man-placed fill, which is consistent with the published geologic map discussed later in this report that depicts the site as being underlain at shallow depths by modified land. The report prepared by AESI in 1998 concluded that settlement of existing fill placed prior to the 1960’s likely caused or contributed to the structural settlement investigated in 1998. In 2000, AESI performed a limited geotechnical investigation and made recommendations for repair of failing pavement and expansion of the bus lane. Two shallow hand explorations Subsurface Exploration, Geologic Hazard, Infiltration Feasibility, Olympic View K-8 School and Preliminary Geotechnical Engineering Report Federal Way, Washington Project and Site Conditions November 4, 2020 ASSOCIATED EARTH SCIENCES, INC. ART/ld - 20200286E001-2 Page 3 completed in the south parking lot encountered materials interpreted as weathered lodgement till sediments at shallow depths. 3.0 SITE EXPLORATION Our field investigation for the current study was conducted in October 2020 and included advancing eight exploration borings, with one of the explorations completed as a groundwater observation well. The existing site conditions, and the approximate locations of subsurface explorations referenced in this study, are presented on the “Site and Exploration Plan” (Figure 2). The various types of sediments, as well as the depths where the characteristics of the sediments changed, are indicated on the exploration logs presented in Appendix A. The depths indicated on the logs where conditions changed may represent gradational variations between sediment types. If changes occurred between sample intervals in our exploration borings, they were interpreted. Our explorations were approximately located in the field by measuring from known site features depicted on the aerial photograph used as a basis for Figure 2. The conclusions and recommendations presented in this report are based, in part, on the explorations completed for this study. The number, locations, and depths of the explorations were completed within site and budgetary constraints. Because of the nature of exploratory work below ground, extrapolation of subsurface conditions between field explorations is necessary. It should be noted that differing subsurface conditions may be present due to the random nature of deposition and the alteration of topography by past grading and/or filling. The nature and extent of variations between the field explorations may not become fully evident until construction. If variations are observed at that time, it may be necessary to re-evaluate specific recommendations in this report and make appropriate changes. 3.1 Exploration Borings For this study, the eight exploration borings were completed by advancing an 8-inch, outside-diameter, hollow-stem auger using a track-mounted drill. During the drilling process, samples were generally obtained at 2½- to 5-foot-depth intervals. The borings were continuously observed and logged by a geologist from our firm. The exploration logs presented in Appendix A are based on the field logs, drilling action, visual observation of the samples collected, and laboratory grain-size testing data included in this report. Disturbed, but representative samples were obtained by using the Standard Penetration Test (SPT) procedure in accordance with ASTM International (ASTM) D-1586. This test and sampling method consists of driving a standard 2-inch, outside-diameter, split-barrel sampler a distance of 18 inches into the soil with a 140-pound hammer free-falling a distance of 30 inches. The number of blows for each 6-inch interval is recorded, and the number of blows required to drive the Subsurface Exploration, Geologic Hazard, Infiltration Feasibility, Olympic View K-8 School and Preliminary Geotechnical Engineering Report Federal Way, Washington Project and Site Conditions November 4, 2020 ASSOCIATED EARTH SCIENCES, INC. ART/ld - 20200286E001-2 Page 4 sampler the final 12 inches is known as the Standard Penetration Resistance (“N”) or blow count. If a total of 50 is recorded within one 6-inch interval, the blow count is recorded as the number of blows for the corresponding number of inches of penetration. The resistance, or N-value, provides a measure of the relative density of granular soils or the relative consistency of cohesive soils; these values are plotted on the attached exploration boring logs. The samples obtained from the split-barrel sampler were classified in the field and representative portions placed in watertight containers. The samples were then transported to our laboratory for further visual classification and laboratory testing. 3.2 Groundwater Observation Well One groundwater observation well was installed in EB2-W. This well consists of a 2-inch-diameter polyvinyl chloride (PVC) Schedule-40 well casing with threaded connections, the lower 10 feet of which is finely slotted (0.010-inch machine slot) well screen to allow water inflow. The annular space around the well screen was backfilled with clean sand, and the upper portion of annulus was sealed with bentonite chips and concrete. A flush-mounted steel monument was placed over the top of the wellhead for protection. The as-built configuration of the well is illustrated on the boring log in Appendix A. Within a week after installation, an AESI representative developed the well by adding several well volumes of water. The well is dry. 4.0 SUBSURFACE CONDITIONS 4.1 Regional Geologic Map and Information by Others Published geologic mapping for the site and immediate vicinity were reviewed on the United States Geological Survey (USGS) National Geologic Map Database1 , and on the Washington State Department of Natural Resources (DNR) Geologic Information Portal 2. These published regional geologic maps indicate that the site is underlain at shallow depths by modified land created during previous earthwork onsite. Vashon ice-contact sediments are mapped adjacent to the north of the site, Vashon lodgement till is mapped adjacent to the east and south, and Vashon advance outwash is mapped to the west. Published mapping suggests that the depth from the existing ground surface onsite to the base of the advance outwash is on the order of 60 feet. This estimated depth to the base of advance outwash can be important for stormwater infiltration feasibility, and is generally consistent with our interpretation of the sediments encountered in explorations for this study. 1 https://ngmdb.usgs.gov/ngmdb/ngmdb_home.html 2 https://www.dnr.wa.gov/geologyportal Subsurface Exploration, Geologic Hazard, Infiltration Feasibility, Olympic View K-8 School and Preliminary Geotechnical Engineering Report Federal Way, Washington Project and Site Conditions November 4, 2020 ASSOCIATED EARTH SCIENCES, INC. ART/ld - 20200286E001-2 Page 5 4.2 Site Stratigraphy Subsurface conditions at the project site were inferred from the field explorations accomplished for this study, visual reconnaissance of the site, and review of selected applicable geologic literature. As shown on the exploration logs, soils encountered at the site consisted of fill of variable thickness overlying native sediments interpreted as Vashon advance outwash. The following section presents more detailed subsurface information on the sediment types encountered at the site. Topsoil Organic-rich brown topsoil and grass were encountered at the ground surface in all borings except EB-4 which was drilled through existing asphalt paving. The observed depths of topsoil ranged between 6 and 12 inches at the boring locations and are shown on the exploration logs. Fill Fill soils (those not naturally placed), were encountered in all of our eight explorations with depths ranging from 6.5 to greater than 21 feet below the existing ground surface. Fill depth at three boring locations exceeded the depth drilled. Figures 2 and 3 of this report include the observed fill depths at each of the exploration locations. The fill generally consisted of medium dense to very dense, moist, brown, fine to medium sand with variable silt content and variable gravel content. Looser fill with organic content was encountered in exploration borings EB-5 and EB-7 at depths ranging between 8 and 15 feet below existing ground surface. Existing fill is not recommended for foundation support and may require remedial preparation below new paving. Excavated existing fill material is suitable for reuse in structural fill applications if such reuse is specifically allowed by project plans and specifications, if excessively organic and any other deleterious materials are removed, and if moisture content is adjusted to allow compaction to the specified level and to a firm and unyielding condition. Existing fill is not suitable for infiltration of stormwater. Vashon Advance Outwash Stratigraphically underlying the fill, five of our explorations encountered typically dense to very dense, stratified sand with varying amounts of silt and gravel interpreted as Vashon advance outwash. The observed depth to advance outwash sediments ranged from 6.5 to greater than 21 feet below the existing ground surface. As previously noted three borings did not penetrate deep enough to reach advance outwash sediments. We anticipate that advance outwash sediments are present below the entire site, and that explorations that did not encounter advance outwash were terminated at depths too shallow to reach the advance outwash. Advance outwash was deposited by meltwater streams from an advancing ice sheet and was glacially Subsurface Exploration, Geologic Hazard, Infiltration Feasibility, Olympic View K-8 School and Preliminary Geotechnical Engineering Report Federal Way, Washington Project and Site Conditions November 4, 2020 ASSOCIATED EARTH SCIENCES, INC. ART/ld - 20200286E001-2 Page 6 overridden and compacted. Advance outwash is suitable for support of aggregate piers, and for direct support of structural loads when prepared as recommended in this report. Advance outwash may contain a significant fine-grained fraction, and may be sensitive to excess moisture during placement in structural fill applications. Due to the depth below existing grade where it was encountered, advance outwash is unlikely to be handled in substantial quantities during construction of the proposed project. Reuse of advance outwash in structural fill applications is feasible if allowed by project specifications, and will require drying to achieve moisture contents within 1 to 2 percent of optimum for compaction purposes. If stormwater infiltration is included in the project, advance outwash would serve as the receptor for stormwater infiltration systems. 4.3 Hydrology Groundwater was not encountered in any of the exploration borings for this study at the time they were completed (October 2020). Perched groundwater was not observed, but is possible during the wetter winter months within existing fill or within the Vashon advance outwash above localized silty interbeds. Perched water occurs when surface water infiltrates down through relatively permeable soils, such as existing fill or coarser-grained advance outwash strata, and becomes trapped or “perched” atop a comparatively low-permeability barrier, such as silty interbeds within the fill or advance outwash. When water becomes perched within fill, it may travel laterally and may follow flow paths related to permeable zones that may not correspond ground surface topography. The presence and quantity of groundwater will largely depend on the soil grain-size distribution, topography, seasonal precipitation, site use, on- and off-site land usage, and other factors. A groundwater observation well was installed at EB-2W and was screened within the Vashon advance outwash sediments between 65 and 75 feet below existing ground surface. The well will be used to monitor groundwater fluctuations throughout the next year. The well was dry when it was installed, and is useful to demonstrate a substantial interval of unsaturated advance outwash below future stormwater infiltration facilities. 4.4 Laboratory Testing Grain-Size Analysis AESI performed six grain-size analyses (sieves) on representative samples of fill and Vashon advance outwash sediments. The grain-size analyses test results are included in Appendix A. Subsurface Exploration, Geologic Hazard, Infiltration Feasibility, Olympic View K-8 School and Preliminary Geotechnical Engineering Report Federal Way, Washington Geologic Hazards and Mitigations November 4, 2020 ASSOCIATED EARTH SCIENCES, INC. ART/ld - 20200286E001-2 Page 7 II. GEOLOGIC HAZARDS AND MITIGATIONS We reviewed mapped geologic hazards on the City of Federal Way Critical Areas Map 1 and King County iMap2, and the previously referenced DNR map. The reviewed maps do not indicate the presence of regulated critical slopes, liquefaction areas, or erosion hazard areas on or immediately adjacent to the project. The DNR map shows an inferred tectonic fault trace in close proximity to the northeast corner of the site which is discussed in further detail below. 5.0 LANDSLIDE HAZARDS AND MITIGATIONS The topography for most of the site is relatively flat to gently sloping. We reviewed topographic contours presented on Figures 2 and 3 created from LIDAR data. A fill slope with inclinations of 20 to 30 percent is present on the western portion of the site. A fill slope with inclinations of 20 to 25 percent is present on the northeastern portion of the site. Based on visual reconnaissance of the site, the existing slopes (west, north, and northeast) appear to have performed well, with no visual indication of unusual erosion or slope instability. No emergent seepage was observed on the slopes during our site visit. Based on the relatively uniform inclinations, the slopes appear to have resulted from previous grading. Given the subsurface conditions on the site and the inclination and height of the slopes, it is our opinion that the risk of damage to the proposed improvements by landslide activity on these slopes under both static and seismic conditions is low. No detailed quantitative assessment of slope stability was completed as part of this study, and none is warranted to support the project as currently proposed, in our opinion. 6.0 SEISMIC HAZARDS AND MITIGATIONS The site does not include areas designated as Seismic Hazard Areas on the previously referenced City of Federal Way Critical Areas Map. The following discussion is a more general assessment of seismic hazards that is intended to be useful to the project design team in terms of understanding seismic issues, and to the structural engineer for preliminary structural design. Earthquakes occur regularly in the Puget Lowland. The majority of these events are small and are usually not felt by people. However, large earthquakes do occur, as evidenced by the 1949, 7.2-magnitude event; the 1965, 6.5-magnitude event; and the 2001, 6.8-magnitude event. 1 https://www.cityoffederalway.com/sites/default/files/maps/sensitive_2016.pdf 2 https://gismaps.kingcounty.gov/iMap/ Subsurface Exploration, Geologic Hazard, Infiltration Feasibility, Olympic View K-8 School and Preliminary Geotechnical Engineering Report Federal Way, Washington Geologic Hazards and Mitigations November 4, 2020 ASSOCIATED EARTH SCIENCES, INC. ART/ld - 20200286E001-2 Page 8 The 1949 earthquake appears to have been the largest in this region during recorded history and was centered in the Olympia area. Evaluation of earthquake return rates indicates that an earthquake of the magnitude between 5.5 and 6.0 is likely within a given 20-year period. Generally, there are three types of potential geologic hazards associated with large seismic events: 1) surficial ground rupture, 2) liquefaction, and 3) ground motion. The potential for each of these hazards to adversely impact the proposed project is discussed below. 6.1 Surficial Ground Rupture Generally, the largest earthquakes that have occurred in the Puget Sound area are sub-crustal events with epicenters ranging from 50 to 70 kilometers in depth. Earthquakes that are generated at such depths usually do not result in fault rupture at the ground surface. Current research indicates that surficial ground rupture is possible in areas close to the Tacoma Fault Zone, the closest mapped fault zone to the project. We reviewed mapped faults on the Washington State Department of Natural Resources Geologic Map Portal3. The DNR map shows an inferred tectonic fault trace in close proximity to the northeast corner of the site. Faults in the project area are inferred from geophysical data, and if present are covered by thick layers of glacial sediments that make them difficult to locate precisely. This proposal does not include costs for an in-depth analysis of the inferred fault, but such analysis is possible. The Puget Sound region has several mapped and inferred fault traces and fault zones. Faults have the potential to displace during an earthquake, and can increase the potential for damage as compared to locations where earthquake shaking risks alone are possible. We are available to discuss mapped faulting further on request. 6.2 Liquefaction Liquefaction is a temporary loss in soil shear strength that can occur when loose granular soils below the groundwater table are exposed to cyclic accelerations, such as those that occur during earthquakes. The observed site sediments were observed to be unsaturated and are not expected to be prone to liquefaction due to their generally high density and absence of shallow groundwater. A detailed liquefaction hazard analysis was not performed as part of this study, and none is warranted, in our opinion. 6.3 Ground Motion/Seismic Site Class (2015 International Building Code) Structural design of the new building should follow 2015 International Building Code (IBC) standards. We recommend that the project be designed in accordance with Site Class “D” 3 https://www.dnr.wa.gov/geologyportal Subsurface Exploration, Geologic Hazard, Infiltration Feasibility, Olympic View K-8 School and Preliminary Geotechnical Engineering Report Federal Way, Washington Geologic Hazards and Mitigations November 4, 2020 ASSOCIATED EARTH SCIENCES, INC. ART/ld - 20200286E001-2 Page 9 in accordance with the 2015 IBC, and the publication American Society of Civil Engineers (ASCE) 7 referenced therein, the most recent version of which is ASCE 7-10. If the project will be permitted under the 2018 version of the IBC, we should be allowed to review the Site Class recommendations presented above. 7.0 EROSION CONTROL Project plans should include implementation of temporary erosion controls in accordance with local standards of practice. Control methods should include limiting earthwork to seasonally drier periods if possible, use of perimeter silt fences, stabilized construction entrances, and straw mulch in exposed areas. Removal of existing vegetation should be limited to those areas that are required to construct the project, and new landscaping and vegetation with equivalent erosion mitigation potential should be established as soon as practical after grading is complete. During construction, surface water should be collected as close as possible to the source to minimize silt entrainment that could require treatment or detention prior to discharge. Timely implementation of permanent drainage control measures should also be a part of the project plans, and will help reduce erosion and generation of silty surface water onsite. 8.0 CRITICAL AQUIFER RECHARGE AREAS Critical aquifer recharge areas (CARAs) have prevailing geologic conditions associated with infiltration rates that create a high potential for contamination of groundwater resources or contribute significantly to the replenishment of groundwater. The CARAs are classified in part by time of travel (TOT) around individual water supply wells. The TOT refers to the amount of time it takes water to discharge to a well from its point of infiltration. Per FWMC Article V, Chapter 19.145.450: “This article regulates development located within designated capture zones. Six-month, one-year, five-year, and 10-year capture zones are designated as critical aquifer recharge areas under the provisions of the Growth Management Act (Chapter 36.70A RCW) and are established based on proximity to and travel time of groundwater to the city’s public water source wells.” Per FWMC 19.145.460: “As required by WAC 365-196-485 (Critical Areas), the city shall protect the quality and quantity of groundwater used for public water supplies. The Lakehaven Utility District (“LUD”) has designated four capture zones based on proximity to and travel time of groundwater to Group A and Group B public water supplies.” The capture zones include the following: Subsurface Exploration, Geologic Hazard, Infiltration Feasibility, Olympic View K-8 School and Preliminary Geotechnical Engineering Report Federal Way, Washington Geologic Hazards and Mitigations November 4, 2020 ASSOCIATED EARTH SCIENCES, INC. ART/ld - 20200286E001-2 Page 10 (1) Six-month capture zone represents the land area overlaying the six-month time-of-travel zone of any public water source well owned by LUD. (2) One-year capture zone represents the land area overlaying the one-year time-of-travel zone of any public water source well owned by LUD, excluding the land area contained in the six-month capture zone. (3) Five-year capture zone represents the land area overlaying the five-year time-of-travel zone of any public water source well owned by LUD, excluding the land area contained in the six-month and one-year capture zones. (4) Ten-year capture zone represents the land area overlaying the 10-year time-of-travel zone of any public water source well owned by LUD, excluding the land area contained in the six-month, one-year, and five- year capture zones. The site is situated within the 5-year and 10-year capture zone of LUD well 19A. Well 19A is shown on the map of “Critical Aquifer Recharge Areas,” Figure 4. The proposed project will be designed to be protective of groundwater and surface water resources by treating and retaining/detaining stormwater in compliance with City of Federal Way stormwater requirements. The stormwater drainage plan is currently in design. If stormwater infiltration is proposed, additional hydrogeologic analyses will be conducted to support the infiltration design and describe potential impacts and mitigations from development within the CARA. Subsurface Exploration, Geologic Hazard, Infiltration Feasibility, Olympic View K-8 School and Preliminary Geotechnical Engineering Report Federal Way, Washington Preliminary Design Recommendations November 4, 2020 ASSOCIATED EARTH SCIENCES, INC. ART/ld - 20200286E001-2 Page 11 III. PRELIMINARY DESIGN RECOMMENDATIONS 9.0 INTRODUCTION Our explorations indicate that, from a geotechnical engineering standpoint, the proposed project is feasible provided the recommendations contained herein are properly followed. The bearing stratum was observed to vary from 6.5 to greater than 21 feet below the existing ground surface. • We recommend that the new building and any other substantial structures be constructed using a conventional shallow foundation system underlain by ground improvement consisting of the installation of aggregate piers. Other foundation support alternatives are possible, including removing and replacing existing fill or installing foundation piles. We are available to discuss other foundation support approaches on request. • Areas of new paving and other similar ancillary structures should be assessed, and some level of remedial preparation of existing fill may be warranted as outlined in the “Site Preparation” section of this report. • At this time civil engineering plans have not been completed. Subsurface conditions observed in our explorations appear feasible for stormwater infiltration if infiltration- related site constraints can be accommodated. If infiltration is included in the project additional on-site testing and analysis will be required to establish an infiltration rate to be used for design. Since this report is preliminary, AESI should be allowed to review the final project plans once they have been developed to update our recommendations, as necessary. 10.0 SITE PREPARATION Erosion and surface water control should be established around the perimeter of the excavation to satisfy City of Federal Way requirements. 10.1 Building Pad Areas Site preparation should include removal of all existing pavement, structures, buried utilities, and any other deleterious material from below the new building. Floor support recommendations contained later in this report require the placement of at least 2 feet of compacted fill below floor slab areas. The 2 feet of fill may be achieved during planned mass grading, or by excavating Subsurface Exploration, Geologic Hazard, Infiltration Feasibility, Olympic View K-8 School and Preliminary Geotechnical Engineering Report Federal Way, Washington Preliminary Design Recommendations November 4, 2020 ASSOCIATED EARTH SCIENCES, INC. ART/ld - 20200286E001-2 Page 12 existing site soils and replacing as needed to establish the 2 feet of new compacted structural fill. If it is necessary to excavate to achieve 2 feet of compacted fill below the floor slabs, reuse of excavated soil as structural fill will be weather-dependent. Structural fill should be placed in accordance with project specifications and the “Structural Fill” section of this report. The subgrade for the building pad, or for structural fill placement below the building pad, is expected to consist of existing fill. The subgrade should be proof-rolled and compacted. Any areas that are soft, yielding, organic, or otherwise unsuitable should be repaired as needed based on site observations during construction. Structural fill should then be placed to reach planned grades. The building pad should be capped with a working surface of at least 8 inches of crushed rock to facilitate construction of aggregate piers. 10.2 Paving Areas Areas of planned paving should be prepared by stripping existing vegetation and topsoil, removing structures and utilities to be demolished, and excavating to planned paving subgrade elevation. The resulting subgrade should then be evaluated visually, compacted, and proof-rolled. Exposed soils are expected to consist of existing fill. Areas with organic or deleterious material, or areas that yield during proof-rolling should receive additional preparation. 10.3 Allowance Recommendations Because building and paving subgrades will consist of existing fill, some amount of remedial subgrade preparation will likely be needed. We recommend establishing a unit cost in bid documents for removal and export of unsuitable soils, and import of suitable granular fill. The unit prices should be based on in-situ bank cubic yards as the unit of measurement. An allowance should be included to encourage competitive unit pricing during bidding. The allowance language should establish that earthwork allowances are to be used only at the owner’s direction, and in accordance with unit prices. For planning purposes we recommend including 500 cubic yards of export/import in bid documents. This is an arbitrary number intended to encourage competitive pricing, and to allow the owner to budget for anticipated remedial preparation. The actual amount used may be more or less based on field conditions during construction. 10.4 Temporary Cut Slopes In our opinion, stable construction slopes should be the responsibility of the contractor and should be determined during construction based on the conditions encountered at that time. For estimating purposes, however, we anticipate that temporary, unsupported cut slopes in loose to very dense fill and medium dense to very dense advance outwash sediments be planned at a maximum slope of 1.5H:1V (Horizontal:Vertical). Steeper temporary slopes in advance outwash sediments may be feasible if needed depending on site-specific conditions, but may not be Subsurface Exploration, Geologic Hazard, Infiltration Feasibility, Olympic View K-8 School and Preliminary Geotechnical Engineering Report Federal Way, Washington Preliminary Design Recommendations November 4, 2020 ASSOCIATED EARTH SCIENCES, INC. ART/ld - 20200286E001-2 Page 13 needed for the project as currently proposed. Temporary cut slopes may need to be adjusted in the field at the time of construction based on the presence of surface water or perched seepage zones. As is typical with earthwork operations, some sloughing and raveling may occur, and cut slopes may have to be adjusted in the field. In addition, WISHA/OSHA regulations should be followed at all times. 10.5 Site Disturbance Some of the on-site soils contain a high percentage of fine-grained material, which makes them moisture-sensitive and subject to disturbance when wet. The contractor must use care during site preparation and excavation operations so that the underlying soils are not softened, particularly during wet weather conditions. If disturbance occurs in areas of conventional footings, the softened soils should be removed and the area brought to grade with clean crushed rock fill. Because of the moisture-sensitive nature of the soils, we anticipate that wet weather construction would significantly increase the earthwork costs over dry weather construction. 10.6 Winter Construction The existing fill material contains substantial silt and is considered highly moisture-sensitive. Soils excavated onsite will likely require drying during favorable dry weather conditions to allow their reuse in structural fill applications. During winter conditions use of excavated onsite soils in compacted fill applications may not be possible, and the use of imported fill or cement treatment of on-site soils may be needed if sitework will be completed during the winter. Care should be taken to seal all earthwork areas during mass grading at the end of each workday by grading all surfaces to drain and sealing them with a smooth-drum roller. Stockpiled soils that will be reused in structural fill applications should be covered whenever rain is possible. If winter construction is expected, crushed rock fill should be used to provide construction staging areas where exposed soil is present. The stripped subgrade should be observed by the geotechnical engineer, and should then be covered with a geotextile fabric, such as Mirafi 500X or equivalent. Once the fabric is placed, we recommend using a crushed rock fill layer at least 10 inches thick in areas where construction equipment will be used. Soil-cement treatment is another approach to providing a workable site during the winter. We are available to provide more detailed cement-treatment recommendations on request and if allowed by the governing jurisdiction. 10.7 Frozen Subgrades If earthwork takes place during freezing conditions, all exposed subgrades should be allowed to thaw, and then be recompacted prior to placing subsequent lifts of structural fill. Alternatively, the frozen material could be stripped from the subgrade to reveal unfrozen soil prior to placing Subsurface Exploration, Geologic Hazard, Infiltration Feasibility, Olympic View K-8 School and Preliminary Geotechnical Engineering Report Federal Way, Washington Preliminary Design Recommendations November 4, 2020 ASSOCIATED EARTH SCIENCES, INC. ART/ld - 20200286E001-2 Page 14 subsequent lifts of fill. The frozen soil should not be reused as structural fill until allowed to thaw and adjusted to the proper moisture content, which may not be possible during winter months. 11.0 STRUCTURAL FILL Structural should be placed and compacted according to the recommendations presented in this section and requirements included in project specifications. All references to structural fill in this report refer to subgrade preparation, fill type, placement, and compaction of materials, as discussed in this section. If a percentage of compaction is specified under another section of this report, the value given in that section should be used. Structural fill is defined as non-organic soil, acceptable to the geotechnical engineer, placed in maximum 8-inch loose lifts, with each lift being compacted to at least 95 percent of the modified Proctor maximum dry density using ASTM D-1557 as the standard. In the case of roadway and utility trench filling, the backfill should be placed and compacted in accordance with City of Federal Way standards. For planning purposes, we recommend the use of a well-graded sand and gravel for road and utility trench backfill. At this time we are not aware of any planned right-of-way work associated with the project. The contractor should note that AESI should evaluate any proposed fill soils prior to their use in fills. This would require that we have a sample of the material at least 3 business days in advance of filling activities to perform a Proctor test and determine its field compaction standard. Soils in which the amount of fine-grained material (smaller than the No. 200 sieve) is greater than approximately 5 percent (measured on the minus No. 4 sieve size) should be considered moisture-sensitive. Use of moisture-sensitive soil in structural fills is not recommended during the winter months or under wet site and weather conditions. Most of the on-site soils are moisture-sensitive and have natural moisture contents over optimum for compaction and will likely require moisture-conditioning before use as structural fill. In addition, construction equipment traversing the site when the soils are wet can cause considerable disturbance. If import soil is required, a select import material consisting of a clean, free-draining gravel and/or sand should be used. Free-draining fill consists of non-organic soil with the amount of fine-grained material limited to 5 percent by weight when measured on the minus No. 4 sieve fraction and at least 30 percent retained on the No. 4 sieve. A representative from our firm should observe the subgrades and be present during placement of structural fill to observe the work and perform a representative number of in-place density tests. In this way, the adequacy of the earthwork may be evaluated as filling progresses and any problem areas may be corrected at that time. It is important to understand that taking random compaction tests on a part-time basis will not assure uniformity or acceptable performance of a Subsurface Exploration, Geologic Hazard, Infiltration Feasibility, Olympic View K-8 School and Preliminary Geotechnical Engineering Report Federal Way, Washington Preliminary Design Recommendations November 4, 2020 ASSOCIATED EARTH SCIENCES, INC. ART/ld - 20200286E001-2 Page 15 fill. As such, we are available to aid the owner in developing a suitable monitoring and testing frequency. 12.0 FOUNDATIONS Conventional shallow footings may be used for building support when founded on existing fill soils improved by placement of aggregate piers, as previously discussed. Figures 2 and 3 of this report include observed and estimated bearing surface data. Building foundations should be supported by on-site fill soils improved by construction of compacted aggregate piers. Building foundations should be designed for an allowable foundation soil bearing pressure of 5,000 pounds per square foot (psf). This allowable foundation soil bearing pressure may be increased by one-third to accommodate transient wind and seismic loads. Perimeter footings should be buried at least 18 inches into the surrounding soil for frost protection. However, all footings must penetrate to the prescribed bearing stratum, and no footing should be founded in or above organic or loose soils. All footings should have a minimum width of 18 inches. It should be noted that the area bound by lines extending downward at 1H:1V from any footing must not intersect another footing or intersect a filled area that has not been compacted to at least 95 percent of ASTM D-1557. In addition, a 1.5H:1V line extending down from any footing must not daylight because sloughing or raveling may eventually undermine the footing. Thus, footings should not be placed near the edge of steps or cuts in the bearing soils. Foundation settlement parameters are established as part of the aggregate pier design process and are summarized in the following report section. Disturbed soil not removed from footing excavations prior to footing placement could result in increased settlements. All footing areas should be inspected by AESI prior to placing concrete to verify that the design bearing capacity of the soils has been attained and that construction conforms to the recommendations contained in this report. Such inspections may be required by the governing municipality. Perimeter footing drains should be provided, as discussed under the “Drainage Considerations” section of this report. 12.1 Aggregate Piers Aggregate piers are recommended below the new building and any other substantial structures. Aggregate piers are vertical columns of compacted stone that are constructed on the building pad before new foundations are constructed. The purpose of aggregate piers is to both improve existing fill soils and to transmit loads to more competent native bearing soils at depth. Aggregate Subsurface Exploration, Geologic Hazard, Infiltration Feasibility, Olympic View K-8 School and Preliminary Geotechnical Engineering Report Federal Way, Washington Preliminary Design Recommendations November 4, 2020 ASSOCIATED EARTH SCIENCES, INC. ART/ld - 20200286E001-2 Page 16 piers are formed by drilling or displacing the existing soil column to a pre-determined depth with an auger or vibratory mandrel. Crushed rock is fed from the surface and compacted in thin lifts resulting in a column of compacted aggregate and compaction of soils surrounding the pier. Aggregate piers are proprietary systems and are designed by the contractor who installs them. The contractor will determine the depth and diameter of the pier holes and the appropriate spacing. Aggregate pier designs are specifically tailored to a foundation plan, and the locations and depths of foundations should be determined prior to aggregate pier design. Conventional shallow foundations are then constructed above the subgrade after piers have been installed. The aggregate pier contractor should review exploration logs contained in this report carefully. Existing fill soils, such as those observed in our explorations, may contain drilling obstacles. Where drilling obstacles are encountered, the contractor should be prepared to relocate planned piers or remove obstacles, as needed, as part of the base bid work. The aggregate pier design should be based on the following parameters: Footings: Maximum Allowable Bearing Pressure for Footings Supported by Aggregate Piers: 5000 psf Maximum Total Long-Term Settlement for Footings: ≤ 1 inch Maximum Long-Term Differential Settlement of Adjacent Footings: ≤ ½ inch Maximum Aggregate Pier Spacing Under Foundations: 8 feet We recommend full-time construction observation by AESI during pier installation to verify that the piers extend to native bearing soils. Air or water jetting are not acceptable practices during the installation of aggregate piers. 13.0 DRAINAGE CONSIDERATIONS Traffic across the on-site soils when they are damp or wet will result in disturbance of the otherwise firm stratum. Therefore, during sitework and construction, the contractor should provide surface drainage and subgrade protection, as necessary. Subsurface Exploration, Geologic Hazard, Infiltration Feasibility, Olympic View K-8 School and Preliminary Geotechnical Engineering Report Federal Way, Washington Preliminary Design Recommendations November 4, 2020 ASSOCIATED EARTH SCIENCES, INC. ART/ld - 20200286E001-2 Page 17 Any retaining walls and all perimeter foundation walls should be provided with a drain at the footing elevation. Drains should consist of rigid, perforated, PVC pipe surrounded by washed gravel. The level of the perforations in the pipe should be set at the bottom of the footing, and the drains should be constructed with sufficient gradient to allow gravity discharge away from the building. The perforations should be located on the lower portion of the pipe. In addition, any retaining or subgrade walls should be lined with a minimum, 12-inch-thick, washed gravel blanket, backfilled completely with free-draining material over the full height of the wall (excluding the first 1 foot below the surface). Composite drainage mats such as Mira Drain 6000 installed in accordance with the manufacturer’s recommendations may be used in lieu of the free-draining aggregate blanket for walls such as stormwater detention vaults that will not be completed as finished habitable space on the interior. The drainage aggregate or composite drain mats should tie into and freely communicate with the footing drains. Roof and surface runoff should not discharge into the footing drain system, but should be handled by a separate, rigid, tightline drain. To minimize erosion, stormwater discharge or concentrated runoff should not be allowed to flow down any steep slopes. In planning, exterior grades adjacent to walls should be sloped downward away from the structures at an inclination of at least 3 percent to achieve surface drainage. Runoff water from impervious surfaces should be collected by a storm drain system that discharges into the site stormwater system. 14.0 FLOOR SUPPORT Floor slabs can be supported on 2 feet of new structural fill as described in the “Site Preparation” section of this report and need not be underlain by aggregate piers. Foregoing aggregate piers below the floor slab will result in substantial cost savings, but will result in some risk of larger than normal post-construction settlement of floor slabs due to potential variabilities in underlying existing fill which will be relied on for floor support. If the risk of larger than normal floor slab settlement is not acceptable, floor slabs should be supported by aggregate piers in a manner similar to foundation support as previously discussed. All fill placed beneath the slab must be compacted to at least 95 percent of ASTM D-1557. The floors should be cast atop a minimum of 4 inches of washed pea gravel or washed crushed rock to act as a capillary break where moisture migration through the slabs is to be controlled. The capillary break material should be overlain by a 10-mil-thick vapor barrier material prior to concrete placement. American Concrete Institute (ACI) recommendations should be followed for all concrete placement. Subsurface Exploration, Geologic Hazard, Infiltration Feasibility, Olympic View K-8 School and Preliminary Geotechnical Engineering Report Federal Way, Washington Preliminary Design Recommendations November 4, 2020 ASSOCIATED EARTH SCIENCES, INC. ART/ld - 20200286E001-2 Page 18 15.0 FOUNDATION WALLS The following preliminary recommendations may be applied to conventional walls up to 8 feet tall. We should be allowed to offer situation-specific input if any taller walls are planned. All backfill behind foundation walls or around foundation units should be placed in accordance with our recommendations for structural fill and as described in this report. Horizontally backfilled walls, which are free to yield laterally at least 0.1 percent of their height, may be designed to resist lateral earth pressure represented by an equivalent fluid equal to 35 pounds per cubic foot (pcf). Fully restrained, horizontally backfilled, rigid walls that cannot yield should be designed for an equivalent fluid of 50 pcf. Walls with sloping backfill up to a maximum gradient of 2H:1V should be designed using an equivalent fluid of 55 pcf for yielding conditions or 75 pcf for fully restrained conditions. If parking areas are adjacent to walls, a surcharge equivalent to 2 feet of soil should be added to the wall height in determining lateral design forces. As required by the 2015 IBC, retaining wall design should include a seismic surcharge pressure in addition to the equivalent fluid pressures presented above. Considering the site soils and the recommended wall backfill materials, we recommend a seismic surcharge pressure of 5H and 10H psf, where H is the wall height in feet for the “active” and “at-rest” loading conditions, respectively. The seismic surcharge should be modeled as a rectangular distribution with the resultant applied at the midpoint of the walls. If the project will be permitted under the 2018 version of the IBC, we should be allowed to review seismic surcharge recommendations presented above. The lateral pressures presented above are based on the conditions of a uniform backfill consisting of excavated on-site soils or imported structural fill compacted to 90 percent of ASTM D-1557 within about 3 feet of the wall. A higher degree of compaction is not recommended, as this will increase the pressure acting on the walls. A lower compaction may result in settlement of the slab-on-grade or other structures supported above the walls. Thus, the compaction level is critical and must be tested by our firm during placement. Surcharges from adjacent footings or heavy construction equipment must be added to the above values. Perimeter footing drains should be provided for all retaining walls, as discussed under the “Drainage Considerations” section of this report. It is imperative that proper drainage be provided so that hydrostatic pressures do not develop against the walls. Wall drainage recommendations are presented in Section 13.0 of this report. 15.1 Passive Resistance and Friction Factors Lateral loads can be resisted by friction between the foundation and the natural soils or supporting structural fill soils, and by passive earth pressure acting on the buried portions of the foundations. The foundations must be backfilled with structural fill and compacted to at least Subsurface Exploration, Geologic Hazard, Infiltration Feasibility, Olympic View K-8 School and Preliminary Geotechnical Engineering Report Federal Way, Washington Preliminary Design Recommendations November 4, 2020 ASSOCIATED EARTH SCIENCES, INC. ART/ld - 20200286E001-2 Page 19 95 percent of the maximum dry density to achieve the passive resistance provided below. We recommend the following allowable design parameters which include a factor of safety of 1.5: • Passive equivalent fluid = 250 pcf • Coefficient of friction = 0.35 16.0 SHALLOW INFILTRATION FEASIBILITY AND PLANNING LEVEL INFILTRATION ESTIMATES The site is underlain by existing fill material that ranges in thickness from 6.5 to more than 21 feet below the existing ground surface. The existing fill is not suitable for use as an infiltration receptor. Existing fill was observed to be underlain by advance outwash sediments, and the advance outwash was demonstrated to be unsaturated at the time of drilling to a depth of 75 feet at the location of exploration boring EB-2W. Advance outwash at this site is expected to be feasible as a stormwater infiltration receptor if the civil engineering can be formulated to work within the constraints of the subsurface conditions. Infiltration locations should be selected where the thickness of the existing fill is least. Infiltration strategies should include open-bottomed vaults or ponds underlain by gravel-filled finger drains that extend below the base of the facility. These infiltration strategies rely on infiltration potential between about 15 and 30 feet below the ground surface, which will assist in penetrating the existing fill. We are available to work with the project civil engineer to identify suitable infiltration locations and depths. A planning-level infiltration rate of 0.5 to 1 inch per hour (iph) is recommended for conventional shallow infiltration structures such as surficial rain gardens. Deeper systems or systems with pit drains can consider planning-level infiltration rates on the order of 2 to 5 iph. The site is better suited to the deeper style of system due to the depth below grade where the infiltration receptor was observed. Infiltration system design must be based on infiltration rate testing results. Infiltration rate testing was beyond the scope of this study but is required if an infiltration system will be constructed. The site is also located within a designated CARA as discussed in Section 8.0 “Critical Aquifer Recharge Areas.” The CARA designation may require additional analysis of potential water quality impacts associated with stormwater infiltration, but is not expected to disallow infiltration for the project. 16.1 Recommendations for Future Infiltration-Related Study We recommend ongoing measurement of water levels in EB-2W through the winter of 2020-2021. We recommend that when infiltration facility locations and depths have been selected, AESI complete infiltration rate testing and possibly additional subsurface explorations consistent with applicable infiltration system design standards. We recommend that we be allowed to review infiltration-related plans prior to permit application and bidding to verify that Subsurface Exploration, Geologic Hazard, Infiltration Feasibility, Olympic View K-8 School and Preliminary Geotechnical Engineering Report Federal Way, Washington Preliminary Design Recommendations November 4, 2020 ASSOCIATED EARTH SCIENCES, INC. ART/ld - 20200286E001-2 Page 20 they are consistent with our recommendations and to offer comments. When an infiltration plan has been formulated, the need for completion of a CARA impact analysis should be determined. If a CARA analysis is needed it should be completed when infiltration plans for the project have been prepared. Infiltration rate testing, collaboration on infiltration-related portions of project documents, and completion of a CARA study are beyond our currently approved scope of work. If needed these services would be completed based on a supplementary scope of work proposal tailored to support the infiltration plan when one has been prepared. 17.0 PAVEMENT AND SIDEWALK RECOMMENDATIONS The pavement sections included in this report section are for driveway and parking areas onsite, and are not applicable to right-of-way improvements. At this time, we are not aware of any planned right-of-way improvements; however, if any new paving of public streets is required, we should be allowed to offer situation-specific recommendations. Pavement and sidewalk areas should be prepared in accordance with the “Site Preparation” section of this report. Soft or yielding areas should be overexcavated to provide a suitable subgrade and backfilled with structural fill. New paving may include areas subject only to light traffic loads from passenger vehicles driving and parking, and may also include areas subject to heavier loading from vehicles that may include buses, fire trucks, food service trucks, and garbage trucks. In light traffic areas, we recommend a pavement section consisting of 3 inches of hot-mix asphalt (HMA) underlain by 4 inches of crushed surfacing base course. In heavy traffic areas, we recommend a minimum pavement section consisting of 4 inches of HMA underlain by 2 inches of crushed surfacing top course and 4 inches of crushed surfacing base course. The crushed rock courses must be compacted to 95 percent of the maximum density, as determined by ASTM D-1557. All paving materials should meet gradation criteria contained in the current Washington State Department of Transportation (WSDOT) Standard Specifications. Depending on construction staging and desired performance, the crushed base course material may be substituted with asphalt treated base (ATB) beneath the final asphalt surfacing if desired. The substitution of ATB should be as follows: 4 inches of crushed rock can be substituted with 3 inches of ATB, and 6 inches of crushed rock may be substituted with 4 inches of ATB. ATB should be placed over a native or structural fill subgrade compacted to a minimum of 95 percent relative density, and a 1½- to 2-inch thickness of crushed rock to act as a working surface. If ATB is used for construction access and staging areas, some rutting and disturbance of the ATB surface should be expected to result from construction traffic. The general contractor should remove affected areas and replace them with properly compacted ATB prior to final surfacing. Subsurface Exploration, Geologic Hazard, Infiltration Feasibility, Olympic View K-8 School and Preliminary Geotechnical Engineering Report Federal Way, Washington Preliminary Design Recommendations November 4, 2020 ASSOCIATED EARTH SCIENCES, INC. ART/ld - 20200286E001-2 Page 21 18.0 PROJECT DESIGN AND CONSTRUCTION MONITORING We recommend that AESI perform a geotechnical review of the plans prior to final design completion. In this way, we can confirm that our recommendations have been correctly interpreted and implemented in the design. The City of Federal Way may require a plan review by the geotechnical engineer as a condition of permitting. We recommend that AESI be retained to provide geotechnical special inspections during construction, and preparation of a final summary letter when construction is complete. The City of Federal Way may require such geotechnical special inspections. The integrity of the earthwork and foundations depends on proper site preparation and construction procedures. In addition, engineering decisions may have to be made in the field in the event that variations in subsurface conditions become apparent. We have enjoyed working with you on this study and are confident these recommendations will aid in the successful completion of your project. If you should have any questions or require further assistance, please do not hesitate to call. Sincerely, ASSOCIATED EARTH SCIENCES, INC. Kirkland, Washington ______________________________ Aaron R. Turnley, G.I.T. Staff Geologist ______________________________ Bruce W. Guenzler, L.E.G. Kurt D. Merriman, P.E. Senior Associate Geologist Senior Principal Engineer Attachments: Figure 1. Vicinity Map Figure 2. Site and Exploration Plan Figure 3. LIDAR Vicinity Map Figure 4. Critical Aquifer Recharge Areas Appendix A. Exploration Logs Laboratory Testing Results DATA SOURCES / REFERENCES: USGS: 7.5' SERIES TOPOGRAPHIC MAPS, ESRI/I-CUBED/NGS 2013 KING CO: STREETS, CITY LIMITS, PARCELS, PARKS 3/20 LOCATIONS AND DISTANCES SHOWN ARE APPROXIMATE VICINITY MAP OLYMPIC VIEW K-8 SCHOOL FEDERAL WAY, WASHINGTON 20200286E001 11/20 1 ± 0 2000 Feet PROJ NO. NOTE: BLACK AND WHITE REPRODUCTION OF THIS COLOR ORIGINAL MAY REDUCE ITS EFFECTIVENESS AND LEAD TO INCORRECT INTERPRETATION DATE:FIGURE:G:\GIS_Projects\aaY2020\200286 Olympic View\aprx\200286E001 F1 VM_ OlyView.aprx | 200286E001 F1 VM_ OlyView | 11/2/2020 12:14 PM¥ ¬« ¬«509 !(26th Ave SWSW 327th St Pierce County King County SITE Pierce County King County !(± BLACK AND WHITE REPRODUCTION OF THIS COLOR ORIGINAL MAY REDUCE ITS EFFECTIVENESS AND LEAD TO INCORRECT INTERPRETATION G:\GIS_Projects\aaY2020\200286 Olympic View\aprx\20200286E001 F2 ES_OlyView.aprx | 20200286E001 F2 ES_OlyView | 11/2/2020 12:12 PMPROJ NO.DATE:FIGURE: 0 150 FEET DATA SOURCES / REFERENCES: PSLC: KING COUNTY 2016, GRID CELL SIZE IS 3'. DELIVERY 2 FLOWN 2/25/16 - 3/28/16 CONTOURS FROM LIDAR KING CO: STREETS, PARCELS, 3/20 AERIAL PICTOMETRY INT. 2019 LOCATIONS AND DISTANCES SHOWN ARE APPROXIMATE 20200286E001 11/20 2 EXISTING SITE AND EXPLORATION PLAN OLYMPIC VIEW K-8 SCHOOL FEDERAL WAY, WASHINGTON SW323r d S t26th Ave SWSW 327th St EB-1, 16ft EB-2W, 13ft EB-3, 8ft EB-4, 17ft EB-5, 14ft EB-6, 21ft EB-7, 21ft EB-8, 6.5ft 300 290 280 270 260 240 230 3103003 1 0300 330320310 250 290 250 EagleView Technologies, Inc. LEGEND SITE EXPLORATION BORING, DEPTH OF FILL - 2020 MONITORING WELL, DEPTH OF FILL - 2020 CONTOUR 50 FT CONTOUR 2 FT Pierce County King County ± BLACK AND WHITE REPRODUCTION OF THIS COLOR ORIGINAL MAY REDUCE ITS EFFECTIVENESS AND LEAD TO INCORRECT INTERPRETATION G:\GIS_Projects\aaY2020\200286 Olympic View\aprx\20200286E001 F3 Lidar_OlyView.aprx | 20200286E001 F3 Lidar_OlyView | 11/2/2020 12:01 PMPROJ NO.DATE:FIGURE: 0 500 FEET DATA SOURCES / REFERENCES: PSLC: KING COUNTY 2016, GRID CELL SIZE IS 3'. DELIVERY 2 FLOWN 2/25/16 - 3/28/16 CONTOURS FROM LIDAR KING CO: STREETS, PARCELS, 3/20 AERIAL PICTOMETRY INT. 2019 LOCATIONS AND DISTANCES SHOWN ARE APPROXIMATE 20200286E001 11/20 3 LIDAR BASED TOPOGRAPHY OLYMPIC VIEW K-8 SCHOOL FEDERAL WAY, WASHINGTON Olympic View Park Alderbrook Park21st Ave SW26thAveSW32nd A v e S W 30thAveSW36thAveSWSW323rdSt 22nd Ave SW35thAveSWSW330t hSt SW 328th St 17thAveSW19thAveSW33rdAveSW18thAveSW 28thAveSW16thAveSWS W 320th S tSW 320th St 24thAveSWSW 325thSt SW 327th St SW 326th St SW 322nd St EB-1, 16ft EB-2W, 13ft EB-3, 8ft EB-4, 17ft EB-5, 14ftEB-6, 21ft EB-7, 21ft EB-8, 6.5ft 30 0 25 0200150 3503003503502 5 0250 3 5 0 300 LEGEND SITE EXPLORATION BORING, DEPTH OF FILL - 2020 MONITORING WELL, DEPTH OF FILL - 2020 CONTOUR 50 FT CONTOUR 10 FT WELL 19A WELL 20A WELL 23A WELL 17 WELL 18 WELL 7 WELL 15 WELL 10 WELL 10A WELL 17A TACOMA WATER DIVISION CITY OFLAKEHAVEN WATER AND SEWER DISTRICTPROJ NO. NOTE: BLACK AND WHITE REPRODUCTION OF THIS COLOR ORIGINAL MAY REDUCE ITS EFFECTIVENESS AND LEAD TO INCORRECT INTERPRETATION DATE:FIGURE: ±G:\GIS_Projects\aaY2020\200286 Olympic View\aprx\20200286E001 F4 CARA_OlyView.aprx | 20200286E001 F4 CARA_OlyView | 10/31/2020 1:21 PMDATA SOURCES / REFERENCES: DOH 12/19: WELLHEAD PROTECTION AREAS, LHWD GROUP A USGS: 7.5' SERIES TOPOGRAPHIC MAPS, ESRI/I-CUBED/NGS 2013 LOCATIONS AND DISTANCES SHOWN ARE APPROXIMATE 0 2000 Feet WELLHEAD PROTECTION ZONES OLYMPIC VIEW K-8 SCHOOL FEDERAL WAY, WASHINGTON 20200286E001 11/20 4 LEGEND SITE SITE BUFFER 1300' WATER DISTRICT SERVICE BOUNDARY TIME OF TRAVEL 6 MONTH 1 YEAR 5 YEAR 10 YEAR APPENDIX A Exploration Logs Laboratory Testing Results 23 22 22 50/6" 34 22 20 43 50/5" S-1 S-2 S-3 S-4 S-5 Bottom of exploration boring at 21 feet No groundwater encountered. Grass - 4 inches Fill Medium dense, moist, brownish gray, gravelly, fine to medium SAND, trace silt (SP). Hand dug 0 to 2 feet to clear irrigation. Moist, grayish brown, silty, fine to medium SAND, some broken gravel (SM). Driller notes chattering at 7.5 feet. Moist, brown, silty, fine to medium, SAND, some gravel; broken gravel in tip; poor recovery (SM). As above. Vashon Advance Outwash Lower 2 inches: moist, grayish brown, fine to medium SAND, some silt; massive (SP-SM). Driller notes chattering at 17 feet. No recovery. 1 of 1 NAVD88 ART2" OD Split Spoon Sampler (SPT) 3" OD Split Spoon Sampler (D & M)Water LevelProject Name JHSWater Level ()Approved by: 30 Blows/Foot Samples Ground Surface Elevation (ft) Grab SampleSymbol 8 40 Datum Hammer Weight/Drop Sampler Type (ST): 288 5 10 15 20 25 EB-1 Ring Sample No RecoveryGraphic 10 Other TestsHole Diameter (in) DESCRIPTION Driller/Equipment Blows/6"Exploration Boring Water Level at time of drilling (ATD) Olympic View K-8 School M - Moisture Project Number 20 Federal Way, WA Date Start/Finish CompletionLocation Sheet Depth (ft)S T Exploration Number 20200286E001 10/7/20,10/7/20 Logged by: Shelby Tube Sample 140# / 30 Boretec / EC-95 Track Mounted Drill WellAESIBOR 20200286E001.GPJ November 3, 20204444 5050/6" 4242 5050/5" 17 28 40 45 22 29 9 10 12 14 26 30 10 13 13 Flush mount monument Concrete 0 to 2.5 feet Bentonite chips 2.5 to 62 feet 2-inch I.D. Sch 40 PVC casing 0 to 65 feet Fill Medium dense, moist, brownish tan, silty, fine to medium SAND, trace gravel, trace organics (SM). Hand dug 0 to 2.5 feet to clear irrigation. Upper 6 inches: moist, brownish tan with some iron oxide staining, silty, fine to medium SAND, trace gravel, trace organics (SM). Lower 12 inches: moist, grayish brown, silty, gravelly, SAND; contains broken gravel (SM). Driller notes drill chatter. As above (SM). Vashon Advance Outwash Moist, brownish gray, fine to medium SAND, trace silt, trace gravel; massive (SP). Driller notes drill chatter. Moist, grayish brown, fine to coarse SAND, some silt, trace gravel (broken); poor recovery (SP-SM). Moist, brownish gray, silty, fine to coarse SAND, some gravel; unsorted (SM). Well Number 140# / 30 Project Name Elevation (Top of Well Casing)Water LevelApproved by: Water Level at time of drilling (ATD) 20200286E001 Water Level Elevation M - Moisture S T Surface Elevation (ft) Project Number Date Start/Finish Hammer Weight/Drop JHS Grab Sample 3" OD Split Spoon Sampler (D & M) EB-2W Location 1 of 3 10/7/20,10/7/20 Federal Way, WA Sampler Type (ST): WELL CONSTRUCTION GraphicSymbolBlows/6"Sheet 5 10 15 20 25 Boretec / EC-95 Track Mounted Drill ~286.7 Ring Sample Logged by: Olympic View K-8 School 8 Depth(ft)DESCRIPTION 2" OD Split Spoon Sampler (SPT) No Recovery Geologic & Monitoring Well Construction Log ART Hole Diameter (in) Shelby Tube Sample Drilling/Equipment Water Level () 287 (NAVD88)NWWELL- B 20200286E001.GPJ BORING.GDT 11/3/20 40 42 49 12 20 28 31 40 41 37 50/6" 27 50/5" 28 50/6" Bentonite chips 2.5 to 62 feet 2-inch I.D. Sch 40 PVC casing 0 to 65 feet Moist, grayish brown, fine to coarse SAND, some silt, some gravel; broken gravel; poor recovery (SM). Moist, grayish brown, medium to coarse SAND, some silt, some gravel (SP-SM). Driller notes drill chatter. As above; fining downward. Moist, brownish gray, fine to medium SAND, trace silt, trace coarse sand; massive (SP). Moist, grayish brown, fine to coarse SAND, some small gravel, trace silt (SP). As above. Well Number 140# / 30 Project Name Elevation (Top of Well Casing)Water LevelApproved by: Water Level at time of drilling (ATD) 20200286E001 Water Level Elevation M - Moisture S T Surface Elevation (ft) Project Number Date Start/Finish Hammer Weight/Drop JHS Grab Sample 3" OD Split Spoon Sampler (D & M) EB-2W Location 2 of 3 10/7/20,10/7/20 Federal Way, WA Sampler Type (ST): WELL CONSTRUCTION GraphicSymbolBlows/6"Sheet 35 40 45 50 55 Boretec / EC-95 Track Mounted Drill ~286.7 Ring Sample Logged by: Olympic View K-8 School 8 Depth(ft)DESCRIPTION 2" OD Split Spoon Sampler (SPT) No Recovery Geologic & Monitoring Well Construction Log ART Hole Diameter (in) Shelby Tube Sample Drilling/Equipment Water Level () 287 (NAVD88)NWWELL- B 20200286E001.GPJ BORING.GDT 11/3/20 37 50/4" 46 50/5" 50/5" 38 50/6" 10/20 Colorado filter sand 62 to 75 feet 2inch I.D. PVC Sch 40 well screen 0.010-inch slot width 65 to 75 feet Threaded end cap Well tag # BJI 136 Moist, grayish brown, fine to medium SAND, trace silt; massive (SP). Moist, brownish gray, fine SAND, some medium sand, trace silt; massive (SP). As above; slightly coarsens downward. Moist, brownish gray, fine SAND, trace silt; massive (SP). Boring terminated at 76 feet Well completed at 75 feet on 10/7/20. No groundwater encountered. Well Number 140# / 30 Project Name Elevation (Top of Well Casing)Water LevelApproved by: Water Level at time of drilling (ATD) 20200286E001 Water Level Elevation M - Moisture S T Surface Elevation (ft) Project Number Date Start/Finish Hammer Weight/Drop JHS Grab Sample 3" OD Split Spoon Sampler (D & M) EB-2W Location 3 of 3 10/7/20,10/7/20 Federal Way, WA Sampler Type (ST): WELL CONSTRUCTION GraphicSymbolBlows/6"Sheet 65 70 75 80 85 Boretec / EC-95 Track Mounted Drill ~286.7 Ring Sample Logged by: Olympic View K-8 School 8 Depth(ft)DESCRIPTION 2" OD Split Spoon Sampler (SPT) No Recovery Geologic & Monitoring Well Construction Log ART Hole Diameter (in) Shelby Tube Sample Drilling/Equipment Water Level () 287 (NAVD88)NWWELL- B 20200286E001.GPJ BORING.GDT 11/3/20 4 5 17 22 26 25 18 17 24 12 18 19 S-1 S-2 S-3 S-4 Bottom of exploration boring at 21.5 feet No groundwater encountered. Grass / Topsoil - 4 inches Fill Moist, brown, fine to medium silty, SAND, some gravel; occasional rootlets; broken gravel in tip; poor recovery (SM). Hand dug to 3 feet to clear irrigation. As above. Driller notes drill chatter. Vashon Advance Outwash Moist, grayish brown, gravelly, silty, fine to coarse SAND; unsorted; massive (SM). Moist, brownish gray, fine to medium SAND, some silt; occasional small gravel otherwise massive (SP-SM). As above; fines down; layer (1 inch thick) of slightly oxidized, silty, fine sand. 1 of 1 NAVD88 ART2" OD Split Spoon Sampler (SPT) 3" OD Split Spoon Sampler (D & M)Water LevelProject Name JHSWater Level ()Approved by: 30 Blows/Foot Samples Ground Surface Elevation (ft) Grab SampleSymbol 8 40 Datum Hammer Weight/Drop Sampler Type (ST): 283 5 10 15 20 25 EB-3 Ring Sample No RecoveryGraphic 10 Other TestsHole Diameter (in) DESCRIPTION Driller/Equipment Blows/6"Exploration Boring Water Level at time of drilling (ATD) Olympic View K-8 School M - Moisture Project Number 20 Federal Way, WA Date Start/Finish CompletionLocation Sheet Depth (ft)S T Exploration Number 20200286E001 10/7/20,10/7/20 Logged by: Shelby Tube Sample 140# / 30 Boretec / EC-95 Track Mounted Drill WellAESIBOR 20200286E001.GPJ November 3, 20202222 51 4141 3737 41 45 42 11 50/6" 27 41 42 S-1 S-2 S-3 Bottom of exploration boring at 16.5 feet No groundwater encountered. Asphalt - 1.5 inches Fill Moist, grayish brown, GRAVEL, some sand, some silt; unsorted (GP-GM). Moist, grayish brown, very gravelly, SAND, some silt; unsorted (SP-SM). Driller notes drill chatter. As above. Driller notes severe drill chattering. As above. 1 of 1 NAVD88 ART2" OD Split Spoon Sampler (SPT) 3" OD Split Spoon Sampler (D & M)Water LevelProject Name JHSWater Level ()Approved by: 30 Blows/Foot Samples Ground Surface Elevation (ft) Grab SampleSymbol 8 40 Datum Hammer Weight/Drop Sampler Type (ST): 289 5 10 15 20 25 EB-4 Ring Sample No RecoveryGraphic 10 Other TestsHole Diameter (in) DESCRIPTION Driller/Equipment Blows/6"Exploration Boring Water Level at time of drilling (ATD) Olympic View K-8 School M - Moisture Project Number 20 Federal Way, WA Date Start/Finish CompletionLocation Sheet Depth (ft)S T Exploration Number 20200286E001 10/7/20,10/7/20 Logged by: Shelby Tube Sample 140# / 30 Boretec / EC-95 Track Mounted Drill WellAESIBOR 20200286E001.GPJ November 3, 202087 61 83 7 12 11 7 8 8 10 11 10 13 19 18 23 24 29 17 25 20 S-1 S-2 S-3 S-4 S-5 S-6 Bottom of exploration boring at 26.5 feet No groundwater encountered. Grass / Topsoil - 4 inches Fill Very moist, grayish brown, silty, fine to medium SAND, some coarse sand, some gravel; contains organics; unsorted (SM). Hand dug to 3 feet to clear irrigation. As above. As above. Moist, brownish tan, silty, fine SAND to fine sandy, SILT; contains organics (SM-ML). Driller notes harder drill action at 14 feet. Vashon Advance Outwash Moist, brown, silty, fine to medium SAND, some gravel, trace coarse sand; massive (SM). Driller notes drill chatter. Moist, brownish gray, silty, fine to medium SAND, some coarse sand, some gravel; massive (SM). Moist, brownish gray, fine to medium SAND, trace gravel, trace silt, trace coarse sand; massive (SP). 1 of 1 NAVD88 ART2" OD Split Spoon Sampler (SPT) 3" OD Split Spoon Sampler (D & M)Water LevelProject Name JHSWater Level ()Approved by: 30 Blows/Foot Samples Ground Surface Elevation (ft) Grab SampleSymbol 8 40 Datum Hammer Weight/Drop Sampler Type (ST): 291 5 10 15 20 25 EB-5 Ring Sample No RecoveryGraphic 10 Other TestsHole Diameter (in) DESCRIPTION Driller/Equipment Blows/6"Exploration Boring Water Level at time of drilling (ATD) Olympic View K-8 School M - Moisture Project Number 20 Federal Way, WA Date Start/Finish CompletionLocation Sheet Depth (ft)S T Exploration Number 20200286E001 10/8/20,10/8/20 Logged by: Shelby Tube Sample 140# / 30 Boretec / EC-95 Track Mounted Drill WellAESIBOR 20200286E001.GPJ November 3, 20202323 1616 2121 3737 53 4545 22 17 16 16 15 14 23 26 25 29 31 32 43 50/6" S-1 S-2 S-3 S-4 S-5 Bottom of exploration boring at 21.5 feet No groundwater encountered. Grass / Topsoil - 4 inches (Till) Fill Moist, brown, silty, fine to medium SAND, some gravel (SM). Hand dug to 3 feet to clear irrigation . Moist, brownish gray, silty, fine to medium SAND, some broken gravel (SM). As above; faint iron oxide staining. Fill Moist, grayish brown, GRAVEL; silty, fine to medium sand in tip; broken gravel in tip; poor recovery (GP-GM). Driller notes drill chatter. Moist, brownish gray, GRAVEL, some fine to medium sand, some silt; broken gravel; unsorted (GP-GM). Moist, brownish gray, sandy, GRAVEL, some silt, trace fine sand; blowcounts are overstated (GP-GM). 1 of 1 NAVD88 ART2" OD Split Spoon Sampler (SPT) 3" OD Split Spoon Sampler (D & M)Water LevelProject Name JHSWater Level ()Approved by: 30 Blows/Foot Samples Ground Surface Elevation (ft) Grab SampleSymbol 8 40 Datum Hammer Weight/Drop Sampler Type (ST): 287 5 10 15 20 25 EB-6 Ring Sample No RecoveryGraphic 10 Other TestsHole Diameter (in) DESCRIPTION Driller/Equipment Blows/6"Exploration Boring Water Level at time of drilling (ATD) Olympic View K-8 School M - Moisture Project Number 20 Federal Way, WA Date Start/Finish CompletionLocation Sheet Depth (ft)S T Exploration Number 20200286E001 10/8/20,10/8/20 Logged by: Shelby Tube Sample 140# / 30 Boretec / EC-95 Track Mounted Drill WellAESIBOR 20200286E001.GPJ November 3, 20203333 2929 51 63 93 9 4 3 4 10 12 13 8 9 41 50/6" 50/6" S-1 S-2 S-3 S-4 S-5 S-6 Bottom of exploration boring at 21.5 feet No groundwater encountered. Grass / Topsoil - 4 inches Fill Hand dug to 3 feet to clear irrigation. Moist, black to brown, silty, medium to coarse SAND, some gravel, trace fine sand; contains organics (SM). As above; poor recovery. As above; some silt inclusions. Fill Moist, brownish gray, fine to medium SAND, trace silt, trace gravel; massive (SP). Driller notes drill chatter at 12 feet. Moist, brown to black, silty, fine to medium SAND to sandy, SILT, some broken gravel; pockets of small organics; organic odor; blowcounts are overstated (SM-ML). moist, brownish gray, silty, fine to medium SAND, trace gravel; faint organic odor; unsorted; poor recovery (SM). 1 of 1 NAVD88 ART2" OD Split Spoon Sampler (SPT) 3" OD Split Spoon Sampler (D & M)Water LevelProject Name JHSWater Level ()Approved by: 30 Blows/Foot Samples Ground Surface Elevation (ft) Grab SampleSymbol 8 40 Datum Hammer Weight/Drop Sampler Type (ST): 288 5 10 15 20 25 EB-7 Ring Sample No RecoveryGraphic 10 Other TestsHole Diameter (in) DESCRIPTION Driller/Equipment Blows/6"Exploration Boring Water Level at time of drilling (ATD) Olympic View K-8 School M - Moisture Project Number 20 Federal Way, WA Date Start/Finish CompletionLocation Sheet Depth (ft)S T Exploration Number 20200286E001 10/8/20,10/8/20 Logged by: Shelby Tube Sample 140# / 30 Boretec / EC-95 Track Mounted Drill WellAESIBOR 20200286E001.GPJ November 3, 202077 2222 1717 91 5050/6" 12 39 48 12 19 23 19 23 25 S-1 S-2 S-3 Bottom of exploration boring at 16.5 feet No groundwater encountered. Grass / Topsoil - 4 inches Fill Hand dug to 3 feet to clear irrigation. Moist, brown, fine to medium SAND, some silt, some gravel (SP-SM). Moist, brown, fine to medium SAND, some silt, some gravel; broken gravel in tip (SP-SM). Driller notes drill chatter. Vashon Advance Outwash Driller notes hard drilling. Moist, brown, gravelly, fine to coarse SAND, trace silt; massive (SP). Moist, brown, fine to medium SAND, some silt, some gravel; occasional beds of fine sand (SP-SM). 1 of 1 NAVD88 ART2" OD Split Spoon Sampler (SPT) 3" OD Split Spoon Sampler (D & M)Water LevelProject Name JHSWater Level ()Approved by: 30 Blows/Foot Samples Ground Surface Elevation (ft) Grab SampleSymbol 8 40 Datum Hammer Weight/Drop Sampler Type (ST): 285 5 10 15 20 25 EB-8 Ring Sample No RecoveryGraphic 10 Other TestsHole Diameter (in) DESCRIPTION Driller/Equipment Blows/6"Exploration Boring Water Level at time of drilling (ATD) Olympic View K-8 School M - Moisture Project Number 20 Federal Way, WA Date Start/Finish CompletionLocation Sheet Depth (ft)S T Exploration Number 20200286E001 10/8/20,10/8/20 Logged by: Shelby Tube Sample 140# / 30 Boretec / EC-95 Track Mounted Drill WellAESIBOR 20200286E001.GPJ November 3, 202087 4242 53 Particle Size Distribution Report PERCENT 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 10.7 12.9 5.4 40.9 25.3 4.86 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: Onsite Sample Number: EB-1 Depth: 0' Client: Project: Project No:Figure gravelly sand, trace silt 1-1/2" 1" 3/4" 5/8" 1/2" 3/8" #4 #8 #10 #20 #40 #60 #100 #200 #270 100.0 94.4 89.3 84.9 83.2 80.6 76.4 72.2 71.0 59.1 30.1 12.7 7.4 4.8 3.9 NP NV NP SP A-1-b 19.6229 15.9931 0.8759 0.6649 0.4244 0.2760 0.2105 4.16 0.98 10/09/2020 10/20/2020 NAS ART/BG 10/07/2020 Federal Way School District Olympic View K-8 School 20200286 E001 PL=LL=PI= USCS (D 2487)=AASHTO (M 145)= D90=D85=D60= D50=D30=D15= D10=Cu=Cc= Remarks *(no specification provided) Particle Size Distribution Report PERCENT 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 14.5 8.5 4.3 11.1 35.0 26.66 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: Onsite Sample Number: EB-2W Depth: 5' Client: Project: Project No:Figure silty gravelly sand 1-1/2" 1" 3/4" 5/8" 1/2" 3/8" #4 #8 #10 #20 #40 #60 #100 #200 #270 100.0 89.4 85.5 84.3 83.8 82.0 77.0 73.5 72.7 69.0 61.6 49.3 38.1 26.6 22.3 NP NV NP SM A-2-4(0) 26.2005 17.9234 0.3921 0.2568 0.0951 10/09/2020 10/20/2020 NAS ART/BG 10/07/2020 Federal Way School District Olympic View K-8 School 20200286 E001 PL=LL=PI= USCS (D 2487)=AASHTO (M 145)= D90=D85=D60= D50=D30=D15= D10=Cu=Cc= Remarks *(no specification provided) Particle Size Distribution Report PERCENT 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 0.0 20.3 13.7 33.4 19.1 13.56 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: Onsite Sample Number: EB-3 Depth: 10' Client: Project: Project No:Figure gravelly silty sand 3/4" 5/8" 1/2" 3/8" #4 #8 #10 #20 #40 #60 #100 #200 #270 100.0 97.2 94.1 90.5 79.7 68.9 66.0 51.4 32.6 22.8 18.1 13.5 11.5 NP NV NP SM A-1-b 9.1845 6.5869 1.3549 0.8028 0.3802 0.0948 10/09/2020 10/20/2020 NAS ART/BG 10/07/2020 Federal Way School District Olympic View K-8 School 20200286 E001 PL=LL=PI= USCS (D 2487)=AASHTO (M 145)= D90=D85=D60= D50=D30=D15= D10=Cu=Cc= Remarks *(no specification provided) Particle Size Distribution Report PERCENT 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 12.1 31.6 13.2 18.1 13.4 11.66 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: Onsite Sample Number: EB-4 Depth: 5-10' Client: Project: Project No:Figure very gravelly sand, some silt 1-1/2" 1" 3/4" 5/8" 1/2" 3/8" #4 #8 #10 #20 #40 #60 #100 #200 #270 100.0 91.5 87.9 84.6 78.4 71.1 56.3 45.5 43.1 33.2 25.0 19.8 16.1 11.6 9.6 NP NV NP SW-SM A-1-a 22.7346 16.1538 5.7777 3.2097 0.6472 0.1281 0.0568 101.74 1.28 10/09/2020 10/20/2020 NAS ART/BG 10/07/2020 Federal Way School District Olympic View K-8 School 20200286 E001 PL=LL=PI= USCS (D 2487)=AASHTO (M 145)= D90=D85=D60= D50=D30=D15= D10=Cu=Cc= Remarks *(no specification provided) Particle Size Distribution Report PERCENT 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 3.1 25.6 19.3 28.8 15.7 7.56 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: Onsite Sample Number: EB-8 Depth: 10' Client: Project: Project No:Figure very gravelly sand, some silt 1" 3/4" 5/8" 1/2" 3/8" #4 #8 #10 #20 #40 #60 #100 #200 #270 100.0 96.9 93.9 90.2 87.0 71.3 55.6 52.0 36.3 23.2 15.0 10.9 7.5 6.2 NP NV NP SW-SM A-1-b 12.5382 8.3901 2.8940 1.8132 0.6086 0.2494 0.1277 22.66 1.00 10/09/2020 10/20/2020 NAS ART/BG 10/08/2020 Federal Way School District Olympic View K-8 School 20200286 E001 PL=LL=PI= USCS (D 2487)=AASHTO (M 145)= D90=D85=D60= D50=D30=D15= D10=Cu=Cc= Remarks *(no specification provided) Particle Size Distribution Report PERCENT 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 5.1 4.5 5.0 19.3 54.2 11.96 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: Onsite Sample Number: EB-8 Depth: 15' Client: Project: Project No:Figure sand, some silt, some gravel 1-1/2" 1" 3/4" 3/8" #4 #8 #10 #20 #40 #60 #100 #200 #270 100.0 96.2 94.9 93.5 90.4 86.5 85.4 78.8 66.1 36.1 19.1 11.9 9.8 NP NV NP SW-SM A-2-4(0) 4.3639 1.8857 0.3764 0.3177 0.2189 0.1138 0.0546 6.89 2.33 10/09/2020 10/20/2020 NAS ART/BG 10/08/2020 Federal Way School District Olympic View K-8 School 20200286 E001 PL=LL=PI= USCS (D 2487)=AASHTO (M 145)= D90=D85=D60= D50=D30=D15= D10=Cu=Cc= Remarks *(no specification provided)