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• <br /> Geotechnical Engineering Report lierracon <br /> Merrill Creek Operations Base Expansion Everett, Washington <br /> December 14, 2020 • Terracon Project No. 81205012 GeoReport <br /> REPORT SUMMARY <br /> Topic 1 Overview Statement 2 <br /> Approx. 16,550 square foot addition to west end of existing operations and transit <br /> coach maintenance building; existing building has a footprint of approximately <br /> 57,500 square feet. <br /> Project • Building addition will occupy area currently covered with concrete pavement <br /> Description • Building addition floor slab will be situated at approximately the existing <br /> grade <br /> • Existing building is supported by conventional spread footings. <br /> • Existing building ground-floor is an on-grade concrete slab. <br /> • Dense to very dense silty sand fill with gravel to depth of about 12 feet(below <br /> existing grade)was observed at both exploration locations. <br /> Geotechnical • Below 12 feet,silty sand,sandy silt, and sand were encountered;soil density <br /> Characterization is variable and range from loose to very dense. <br /> • Groundwater was encountered at a depth of 27 feet below the ground <br /> surface. <br /> Earthwork is expected to be minimal and will consist of removal of existing concrete <br /> Earthwork pavement section, excavation for footings, backfilling around footings, minor cutting <br /> or filling to achieve the floor slab subgrade, and trenching/backfilling for sub-slab <br /> utilities. <br /> Shallow foundations will be sufficient <br /> Shallow Allowable bearing pressure = 3,000 lbs/sq ft(spread and wall footings) <br /> Foundations Expected settlements: < 1-inch total, 1A-inch differential <br /> Detect and remove zones of poor subgrade as noted in Earthwork <br /> Deep Deep foundations are not necessary for this site. <br /> Foundations <br /> Below-Grade One or more under-coach inspection pits may be constructed, plus vaults for <br /> Structures stormwater and paint-booth equipment. <br /> To match existing vehicle pavements around the building expansion, we expect that <br /> a rigid pavement section similar to the existing one will be used, and include <br /> • 9 inches of Portland Cement Concrete (PCC)over <br /> Pavements • 10 inches of compacted granular base <br /> New rigid pavement should be doweled into existing PCC slabs to provide load <br /> transfer across panel joints <br /> General This section contains important information about the limitations of this geotechnical <br /> Comments engineering report. <br /> 1. If the reader is reviewing this report as a pdf,the topics above can be used to access the appropriate section <br /> of the report by simply clicking on the topic itself. <br /> 2. This summary is for convenience only. It should be used in conjunction with the entire report for design <br /> purposes. <br /> Responsive • Resourceful ■ Reliable <br />