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22-102123-UP-Geotechnical Report_-5-09-2022 Kirkland | Tacoma | Mount Vernon 425-827-7701 | www.aesgeo.com February 8, 2021 Project No. 20200453E001 Federal Way Public Schools 33330 8th Avenue South Federal Way, Washington 98003 Attention: Mr. Delin Huang Subject: Preliminary Geotechnical Engineering Recommendations Federal Way High School Memorial Field Improvements 1344 South 308th Street Federal Way, Washington Dear Mr. Huang: This letter-report summarizes Associated Earth Sciences, Inc.’s (AESI’s) preliminary geotechnical engineering recommendations for the proposed improvements to the Federal Way High School Memorial Field located at 1344 South 308th Street in Federal Way, Washington. Our recommendations are based on review of our previous work completed on the Federal Way High School site, which has included subsurface explorations, geotechnical engineering studies, and construction monitoring. Our work was completed in accordance with our proposal, dated December 21, 2020. SITE AND PROJECT DESCRIPTION The project site is the Memorial Field athletics field and parking lot at the southwest corner of the existing Federal Way High School property, located at 1344 South 308th Street in Federal Way, Washington (King County Parcel No. 0821049001). The site is shown on the “Vicinity Map,” Figure 1. The parking lot and stadium are roughly rectangular-shaped portions of the high school parcel and are bound to the north by the high school baseball field, to the east by a parking lot and the school building, to the south by South 308th Street, and to the west by existing stormwater ponds and residential development. The football field is surrounded by an athletic track and oriented with its long axis north-south. Grandstands overlook the field from the east and west sides. The existing parking lot is gravel-surfaced, with ingress and egress at the east and west ends of the parking lot. The ground surface is basically flat over most of the parking lot and Federal Way High School Memorial Field Improvements Preliminary Federal Way, Washington Geotechnical Engineering Recommendations February 8, 2021 ASSOCIATED EARTH SCIENCES, INC. NS/ld - 20200453E001-3 Page 2 field and then slopes upward to the east at an inclination of about 2 Horizontal:1 Vertical (2H:1V) on the east side of the field. Overall vertical relief across the site is on the order of 25 feet. Details of the proposed improvements are limited at this time, but the improvements are planned to occur in two phases. The first phase would consist of improvements to the parking area and the second phase would consist of improvements to the stadium and field. Specifically, the proposed improvements include the following: • replacement of several stadium structures, including grandstands, bathrooms, and other accessory structures; • new asphalt pavement in the stadium parking lot; • new pavement of pathways throughout the site; • replacement of track surfaces and artificial turfs; • improvements to infrastructure for site lighting, security, and other systems; and • possibly frontage improvements. The purpose of our work was to use existing subsurface information to develop preliminary geotechnical engineering design recommendations for pavement, foundations, structural fills, and seismic site class per current code requirements. The recommendations contained in the letter-report are considered preliminary. The subsurface conditions that are the basis for the recommendations in the letter-report were extrapolated from site explorations advanced for the neighboring high school project. The assumed subsurface conditions should be verified by site-specific explorations or by observation of exposed subgrades at the time of construction. If differing subsurface conditions are encountered, the conclusions and recommendations contained in this letter-report should be confirmed or changed to reflect the actual conditions encountered. PREVIOUS SUBSURFACE EXPLORATION In order to collect subsurface information at the areas of the proposed improvements, we reviewed our previous study at the site, which included drilling 10 exploration borings on January 2 and 3, 2014 using a hollow-stem auger drilling rig. Our findings and analyses were reported in our geotechnical engineering report titled, “Subsurface Exploration, Geologic Hazards, and Geotechnical Engineering Report, Federal Way High School Replacement,” dated as revised October 31, 2014. Eight of the 2014 exploration borings were drilled at the southeast corner of the parcel near the high school building and two were drilled west of the Memorial Field and parking lot area. The locations of the four nearest exploration borings, EB-4, EB-5, EB-9, and EB-10, are shown on the “Existing Site and Exploration Plan,” Figure 2, and logs of these Federal Way High School Memorial Field Improvements Preliminary Federal Way, Washington Geotechnical Engineering Recommendations February 8, 2021 ASSOCIATED EARTH SCIENCES, INC. NS/ld - 20200453E001-3 Page 3 explorations are included in the Appendix. Additional subsurface explorations were not included in this scope of work. The conclusions and recommendations presented in this letter-report are based on review of our previous exploration borings at the site. The number, locations, and depths of the explorations were completed within site and budgetary constraints. Because of the nature of exploratory work below ground, interpolation of subsurface conditions between field explorations is necessary. It should be noted that differing subsurface conditions may sometimes 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 any 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 letter-report and make appropriate changes. Ground surface elevations and subsurface conditions observed at the exploration boring locations may have been altered by the construction and grading activities that occurred after the exploration during construction of the existing school, and the conditions observed at the time of drilling may no longer be representative of existing conditions. The various types of soil and groundwater elevations, as well as the depths where soil and groundwater characteristics changed, are indicated on the exploration boring logs presented in the Appendix. The depths indicated on the logs where conditions changed may represent gradational variations between sediment types in the field. If changes occurred between sample intervals in our borings, they were interpreted. SUBSURFACE CONDITIONS Subsurface conditions at the project site were inferred from the field explorations accomplished for our 2014 study and review of selected applicable geologic literature. The general distribution of geologic units is shown on the exploration logs. The explorations generally encountered native pre-Fraser sediments overlain in some areas by existing fill. Stratigraphy The following sections present more detailed subsurface information organized from the youngest (shallowest) to the oldest (deepest) sediment types. Federal Way High School Memorial Field Improvements Preliminary Federal Way, Washington Geotechnical Engineering Recommendations February 8, 2021 ASSOCIATED EARTH SCIENCES, INC. NS/ld - 20200453E001-3 Page 4 Existing Fill Fill soils (soils not naturally placed) were encountered at the locations of exploration borings EB-9 and EB-10 to depths of 11 and 7 feet below the ground surface, respectively. The fill generally consisted of loose, silty sand with gravel. Portions of the fill contained organic material. We interpret the encountered fill as likely resulting from past grading activities, including the filling of low areas west of the stadium and field. Fill thickness can vary over short distances and may be deeper than observed in our explorations. Due to the variable density and content, the existing fill soils are not suitable for foundation support. Pre-Fraser Deposits In exploration borings EB-4 and EB-5 and underlying the fill in exploration borings EB-9 and EB-10, sediments consisted of medium dense to very dense, silty, fine to medium sand with gravel, siltier areas, silt beds, and trace organics, interpreted as pre-Fraser deposits. The pre-Fraser deposits were placed prior to the Fraser Glaciation and subsequently compacted by the weight of the overlying glacial ice. The upper 3 to 5 feet of the pre-Fraser deposits were of lower density, interpreted as being due to weathering. The pre-Fraser deposits extended to the full depths explored of approximately 15.9 to 21.5 feet, as shown on the exploration logs in the Appendix. The medium dense to very dense material is generally considered suitable for support of light- to heavily-loaded foundations when in an intact, undisturbed condition. This material is moisture- sensitive and susceptible to disturbance when wet. Groundwater We encountered groundwater seepage in exploration borings EB-9 and EB-10 at depths of 10 and 14 feet, respectively. We anticipate that the encountered groundwater likely represents a local groundwater table within the underlying pre-Fraser deposits. We expect that shallow groundwater seepage would likely represent interflow within the existing fill. Interflow occurs when surface water percolates down through the surficial weathered or higher-permeability sediments and becomes perched atop underlying, lower-permeability sediments. It should be noted that the occurrence and level of groundwater seepage at the site may vary in response to such factors as changes in season, precipitation, and site use. The explorations reviewed for this study were completed on January 2 and 3, 2014. PRELIMINARY GEOTECHNICAL DESIGN RECOMMENDATIONS From a geotechnical engineering standpoint, it is our opinion that the site is suitable for the proposed improvements provided the recommendations contained in this letter-report are Federal Way High School Memorial Field Improvements Preliminary Federal Way, Washington Geotechnical Engineering Recommendations February 8, 2021 ASSOCIATED EARTH SCIENCES, INC. NS/ld - 20200453E001-3 Page 5 incorporated into the design and construction of the project. In general, foundations can be supported by medium dense or denser native soils or structural fill, where dense, non-organic existing fill is present under proposed lightly-loaded structures, such as pavement; it may be suitable for structural support provided the subgrade can be compacted to a firm and unyielding condition and with the approval of the geotechnical engineer. The following sections provide preliminary recommendations for seismic site class, site preparation, structural fill, foundations, pavement, and drainage. Seismic Site Class Seismic design shall be in accordance with the 2015 International Building Code (IBC). The native soils at the site are consistent with seismic Site Class “D” as defined in ASCE 7 - Minimum Design Loads for Buildings and Other Structures (2010) as referenced by the 2015 IBC and Site Class “D” seismic design parameters should be used for design. Site Preparation Existing buried utilities, vegetation, topsoil, demolition debris, and any other deleterious materials should be removed where they are located below planned construction areas. All disturbed soils should be removed to expose underlying, undisturbed, native sediments and replaced with structural fill, as needed. All excavations below final grade made for demolition or clearing and grubbing activities should be backfilled, as needed, with structural fill. Erosion and surface water control should be established around the clearing limits to satisfy local requirements. Once clearing and grubbing activities have been completed, existing fill, where encountered, should be addressed. We recommend that existing fill be removed from below areas of planned foundations to expose underlying, undisturbed native sediments, followed by restoration of the planned foundation grade with compacted structural fill. Removal of existing fill should extend laterally beyond the new foundation footprint a minimum of 2 feet. Care should be taken not to disturb support soils of existing foundations, if any will remain. Support soils should be considered those soils within a prism projected downward and outward from existing footings at inclinations of 1H:1V. Where existing fill is removed and replaced with structural fill, conventional shallow foundations may be used for building support. The required depth of removal should be determined in the field based on actual conditions encountered during excavation. Site Disturbance The site soils contained 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 Federal Way High School Memorial Field Improvements Preliminary Federal Way, Washington Geotechnical Engineering Recommendations February 8, 2021 ASSOCIATED EARTH SCIENCES, INC. NS/ld - 20200453E001-3 Page 6 preparation and excavation operations so that the underlying soils are not softened. If disturbance occurs to soils in structural areas, the softened soils should be removed and the area brought to grade with structural fill. Proof-Rolling Following the recommended clearing, stripping, and any planned excavation, the stripped subgrade within large paving areas should be proof-rolled with heavy, rubber-tired construction equipment, such as a fully-loaded, tandem-axle dump truck. Proof-rolling should be performed prior to structural fill placement or foundation excavation. The proof-roll should be monitored by the geotechnical engineer so that any soft or yielding subgrade soils can be identified. Any soft/loose, yielding soils should be removed to expose firm and unyielding subgrade. The subgrade should then be scarified, adjusted in moisture content, and recompacted to the required density. Proof-rolling should only be attempted if soil moisture contents are at or near optimum moisture content. Proof-rolling of wet subgrades could result in further degradation. Low areas and excavations may then be raised to the planned finished grade with compacted structural fill. Subgrade preparation and selection, placement, and compaction of structural fill should be performed under engineering-controlled conditions in accordance with the project specifications. Structural Fill Placement of structural fill may be necessary to establish desired grades at the site or to backfill utility trenches or around foundations. All references to structural fill in this letter-report refer to subgrade preparation, fill type, and placement and compaction of materials as discussed in this section. If a percentage of compaction is specified under another section of this letter-report the value given in that section should be used. After overexcavation/stripping has been performed to the satisfaction of the geotechnical engineer/engineering geologist, the exposed ground surface should be recompacted to a firm and unyielding condition. If the subgrade contains too much moisture, suitable recompaction may be difficult or impossible to attain and should probably not be attempted. In lieu of recompaction, the area to receive fill should be blanketed with washed rock or quarry spalls to act as a capillary break between the new fill and the wet subgrade. Where the exposed ground remains soft and further overexcavation is impractical, placement of an engineered stabilization fabric may be necessary to prevent contamination of the free-draining layer by silt migration from below. After recompaction of the exposed ground is approved by the geotechnical engineer, or a free-draining rock course is laid, structural fill may be placed to attain desired grades. Federal Way High School Memorial Field Improvements Preliminary Federal Way, Washington Geotechnical Engineering Recommendations February 8, 2021 ASSOCIATED EARTH SCIENCES, INC. NS/ld - 20200453E001-3 Page 7 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 International (ASTM) D-1557 as the standard. Utility trench backfill should be placed and compacted in accordance with applicable municipal codes and standards. The top of the compacted fill should extend horizontally a minimum distance of 3 feet beyond footings or pavement edges before sloping down at an angle no steeper than 2H:1V. Fill slopes should either be overbuilt and trimmed back to final grade or surface-compacted to the specified density. We recommend that a clean, free-draining gravel and/or sand be used in structural areas. 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. Soils in which the amount of fine-grained material (smaller than No. 200 sieve) is greater than approximately 5 percent (measured on the minus No. 4 sieve size) should be considered moisture-sensitive. Portions of the site soils contained significant fine-grained fractions and are considered moisture-sensitive. The use of moisture-sensitive soil in structural fills should be limited to favorable dry weather conditions and non-structural areas such as under landscaping. The contractor should note that any proposed fill soils must be evaluated by AESI prior to their use in fills. This would require that we have a sample of the material at least 3 business days in advance to perform a Proctor test and determine its field compaction standard. A representative from our firm should observe the stripped subgrade and be present during placement of structural fill to monitor 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 fill. As such, we are available to aid the owner in developing a suitable monitoring and testing frequency. Foundations In the exploration borings located near the site, suitable bearing soils were observed at depths of about 5 feet in EB-4 and EB-5 east of the site and 8 to 12 feet in EB-9 and EB-10 west of the site. Based on our current understanding of the project, significant foundations are not planned near the western part of the site, where the bearing stratum was encountered relatively deep within the existing detention pond areas. Therefore, we anticipate that any proposed structures can be supported on conventional shallow spread footings. If changes to the proposed improvements include new foundations near the west end of the site, additional field studies Federal Way High School Memorial Field Improvements Preliminary Federal Way, Washington Geotechnical Engineering Recommendations February 8, 2021 ASSOCIATED EARTH SCIENCES, INC. NS/ld - 20200453E001-3 Page 8 may be needed to verify subsurface conditions and depth to bearing soils in the proposed foundation areas. For footings bearing directly on medium dense to dense natural sediments, or on structural fill placed over these materials as described above, we recommend that an allowable foundation soil bearing pressure of 2,500 pounds per square foot (psf) be used for design purposes, including both dead and live loads. An increase of one-third may be used for short-term wind or seismic loading. 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. Anticipated settlement of footings founded as described above should be on the order of 1 inch or less. However, 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 letter-report. Such inspections may be required by the City of Federal Way. Perimeter footing drains should be provided, as discussed under the “Drainage Considerations” section of this letter-report. Floor Support Slab-on-grade floors may be used over medium dense or denser native soils, inorganic existing fills soils re-compacted to 95 percent relative compaction, or over structural fill placed as recommended in the “Site Preparation” and “Structural Fill” sections of this letter-report. Slab design can assume a soil subgrade modulus of 200 pounds per cubic inch (pci) for slabs cast over the medium dense, natural sediments, re-compacted existing fill or properly compacted structural fill placed over these materials. Slab-on-grade floors should be cast atop a minimum of 4 inches of washed pea gravel or washed crushed “chip” rock with less than 3 percent passing the U.S. No. 200 sieve to act as a capillary break. The floors should also be protected from dampness by covering the capillary break layer with an impervious moisture barrier at least 10 mils in thickness. Federal Way High School Memorial Field Improvements Preliminary Federal Way, Washington Geotechnical Engineering Recommendations February 8, 2021 ASSOCIATED EARTH SCIENCES, INC. NS/ld - 20200453E001-3 Page 9 Passive Resistance and Friction Factors All backfill around foundation units should be placed per our recommendations for structural fill and as described in the “Structural Fill” section of this letter-report. Lateral loads can be resisted by friction between the foundation and the natural glacial 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 95 percent of the maximum dry density to achieve the passive resistance provided below. We recommend the following allowable design parameters: Passive equivalent fluid = 350 pounds per cubic foot Coefficient of friction = 0.35 Drainage Considerations Foundations should be provided with foundation drains placed at the bottom of footing or slab elevation. Drains should consist of rigid, perforated, polyvinyl chloride (PVC) pipe surrounded by washed pea gravel. The drains should be constructed with sufficient gradient to allow gravity discharge away from any proposed buildings. Roof and surface runoff should not discharge into the footing drain system, but should be handled by a separate, rigid, tightline drain. In planning, exterior grades adjacent to walls should be sloped downward away from the proposed structures to achieve surface drainage. Pavement Pavement areas should be prepared in accordance with the “Site Preparation” section of this letter-report. If the stripped native soil or existing fill pavement subgrade can be compacted to 95 percent of ASTM D-1557 and is firm and unyielding, no additional overexcavation is required. Soft or yielding areas should be overexcavated to provide a suitable subgrade and backfilled with structural fill. The pavement sections included in this letter-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. The exposed ground should be recompacted to 95 percent of ASTM D-1557 and proof-rolled in accordance with the “Proof-Rolling” section of this letter-report. If required, structural fill may then be placed to achieve desired subbase grades. After the prepared subgrade is approved by the geotechnical engineer, the overlying pavement in areas of planned passenger car driving and parking can consist of a minimum of 2 inches of asphaltic concrete pavement (ACP) underlain by 4 inches of 1¼-inch crushed surfacing base course. In driveway areas subjected to heavier loads, Federal Way High School Memorial Field Improvements Preliminary Federal Way, Washington Geotechnical Engineering Recommendations February 8, 2021 ASSOCIATED EARTH SCIENCES, INC. NS/ld - 20200453E001-3 Page 10 such as that from delivery trucks or school buses, a minimum pavement section consisting of 3 inches of ACP underlain by 2 inches of 5/8-inch crushed surfacing top course and 4 inches of 1¼-inch crushed surfacing base course is recommended. 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. 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. The general contractor should remove affected areas and replace them with properly compacted ATB prior to final surfacing. LIMITATIONS This letter-report has been prepared for the exclusive use of Federal Way Public Schools and their 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 practices in effect in this area at the time our letter-report was prepared. No other warranty, express or implied, is made. CLOSURE Our recommendations should be considered preliminary in that project plans and construction details have not been finalized at the time of this letter-report. We are available to provide additional geotechnical consultation as the project design develops and possibly changes from that upon which this letter-report is based. We recommend that AESI perform a final geotechnical review of the plans prior to final design completion. In this way, our earthwork and foundation recommendations may be properly interpreted and implemented in the design. We are also available to provide geotechnical engineering and monitoring services during construction. The integrity of the foundations and pavement 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. Construction monitoring Federal Way High School Memorial Field Improvements Preliminary Federal Way, Washington Geotechnical Engineering Recommendations February 8, 2021 ASSOCIATED EARTH SCIENCES, INC. NS/ld - 20200453E001-3 Page 11 services are not part of this current scope of work. If these services are desired, please let us know, and we will prepare a proposal. 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 ______________________________ Nicki Shobert, E.I.T. Kurt D. Merriman, P.E. Project Engineer Senior Principal Engineer Attachments: Figure 1. Vicinity Map Figure 2. Existing Site and Exploration Plan Appendix. Exploration Logs 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 FEDERAL WAY HS MEMORIAL FIELD IMPROVEMENTS FEDERAL WAY, WASHINGTON 20200453E001 1/21 1 FEDERAL WAY KING COUNTY KING COUNTY 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:\\kirkfile2\gis\GIS_Projects\aaY2020\200453 Federal Way HS\aprx\20200453E001 F1 VM_FedWayHS.aprx | 20200453E001 F1 VM_FedWayHS | 1/28/2021 5:07 PM¥ ¥5 ¥ ¬«99 ¬«509 !( S 308th St 14thAveS10th Ave S11th Ave SPierce County King County SITE 14thAveSS 308th St11th Ave S480460440440480 460440 440EB-10 EB-9 EB-5 EB-4 EagleView Technologies, Inc. PROJ NO. NOTE: BLACK AND WHITE REPRODUCTION OF THIS COLOR ORIGINAL MAY REDUCE ITS EFFECTIVENESS AND LEAD TO INCORRECT INTERPRETATION DATE:FIGURE:\\kirkfile2\gis\GIS_Projects\aaY2020\200453 Federal Way HS\aprx\20200453E001 F2 ES_FedWayHS.aprx | 20200453E001 F2 ES_FedWayHS | 1/29/2021 10:07 AMDATA 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 0 200 Feet EXISTING SITE AND EXPLORATION PLAN FEDERAL WAY HS MEMORIAL FIELD IMPROVEMENTS FEDERAL WAY, WASHINGTON 20200453E001 1/21 2 Pierce County King County LEGEND SITE EXPLORATION BORING - 2014 PARCEL CONTOUR 20 FT CONTOUR 5 FT APPENDIX Exploration Logs