1610 SE EVERETT MALL WAY Geotech Report 2022-10-25

Subsurface Exploration, Geologic Hazard, and Krebs Property Preliminary Geotechnical Engineering Report Everett, Washington Project and Site Conditions studied and classified in the field by an engineering geologist from our firm. All exploration pits were backfilled immediately after examination and logging. Selected samples were then transported to our laboratory for further visual classification and testing, as necessary. 4.0 SUBSURFACE CONDITIONS Subsurface conditions at the project site were inferred from the field explorations accomplished for this study, visual reconnaissance of the site, and review of applicable geologic literature. As shown on the field logs, the exploration pits generally encountered granular glacial sediments with a small quantity of fill found in one area of the site. The following section presents more detailed subsurface information organized from the upper (youngest) to the lower (oldest) sediment types. 4.1 Stratigraphy Fill Fill soils (those not naturally placed) were encountered at the location of exploration pit EP-6, located in the western portion of the site. The fill was approximately 1 foot thick and generally consisted of medium dense, very moist, gray, silty sand with gravel. Topsoil A surficial organic topsoil layer was encountered at each of the exploration pit locations except EP-6. The thickness of the topsoil layer was approximately '/i foot. The organic topsoil is not suitable for foundation support or for use in a structural fill. Vashon Lodgement Till Sediments generally consisting of an unsorted mixture of loose to medium dense, moist to very moist, reddish brown to tan, silty sand with gravel and scattered cobbles were encountered below the surficial topsoil or fill layer at each of the exploration locations. These sediments typically became very dense, very moist and gray to grayish tan below depths of approximately 2.5 to 4 feet. The reduced density and color variation in the upper 2.5 to 4 feet is interpreted to be due to weathering. We interpret these sediments to be representative of Vashon lodgement till. The Vashon lodgement till was deposited directly from basal debris-laden glacial ice during the Vashon Stade of the Fraser Glaciation approximately 12,500 to 15,000 years ago. The high relatively density characteristic of the Vashon lodgement till is due to its consolidation by the massive weight of the glacial ice from which it was deposited. The lodgement till extended beyond the maximum depths explored of approximately 7 to 11 feet. February 13, 2007 ASSOCIATED EARTH SCIENCES, INC. TJP/Id-KE070023A1-Projects120070023IKEIWP Page 3