1010 N BROADWAY STARBUCKS Geotech Report 2025-07-24

Geotechnical Engineering Evaluation lierracon Broadway& 10th Starbucks E Everett,WA January 9, 2014 Terracon Project No. 81135080 footings, slab-on-grade floors, site drains, pavement sections, and structural fill are presented in the following text sections. ASTM specification codes cited herein refer to the 2010 manual published by the American Society for Testing & Materials. WSDOT codes refer to the 2012 edition of Standard Specifications for Road, Bridge, and Municipal Construction published by Washington State Department of Transportation. 5.1 General Considerations We offer the following comments, conclusions, and recommendations concerning general geotechnical design and construction issues affecting the overall development. Earthwork Considerations: Our borings and laboratory testing disclosed moderately silty soils underlying the site. Because these soils are moisture-sensitive and easily disturbed when wet, we recommend that earthwork be scheduled for extended periods of dry weather. If precipitation occurs prior to or during construction, the near-surface soils could increase in moisture content and become more susceptible to disturbance. Construction activity should be monitored, and should be curtailed if the construction activity is causing subgrade disturbance. A Terracon representative can help with monitoring and developing recommendations to aid in limiting subgrade disturbance. Foundation Considerations: Our borings disclosed about 3 feet of medium dense to dense fill mantling the site. Fill by nature can be highly variable and could vary greatly between sample locations. We recommend complete removal of existing fill below proposed building footings. Footings may bear on at least medium dense native soils or on structural fill placed and compacted in accordance with the recommendations in this report. Seismic Site Class: The International Building Code (IBC) assigns a seismic Site Class on the basis of geological conditions prevailing within a depth of 100 feet below the local ground surface. Although our borings did not extend to a depth of 100 feet, we infer from near-surface soil observations and from available geologic maps that the overall subsurface conditions correspond to Site Class "C" as defined by the IBC. Infiltration Potential: Our scope of work did not include infiltration testing or analysis, but we infer from density and textural properties that the native glacial till deposit underlying the entire site would likely offer a very low percolation rate (probably less than 0.05 to 0.10 inches per hour before a safety factor is applied). As such, the on-site soil conditions are not well suited for stormwater infiltration. Contaminated Soil Considerations: Our scope of work did not include an assessment of environmental risks or possible soil contaminants. However, the presence of imported fill soils on the site inherently carries the possibility of undesired constituents. If contaminated soils are Reliable e Responsive a Convenient ■ Innovative 6