7100 HARDESON RD Geotech Report 2025-03-06

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