6202 ASSOCIATED BLVD Geotech Report 2022-10-25

Proposed Everett Warehouse ZipperGeo Project No. 2152.01 March 5, 2019 Description Value 2015 IBC Site Classification 1 D 1 SS Spectral Acceleration for a Short Period 1.431 g (Site Class B) Si Spectral Acceleration for a 1-Second Period 0.546 g (site Class B) SMs Maximum considered spectral response 1.431 g (Site Class D) acceleration for a Short Period SMi Maximum considered spectral response 0.819 g (Site Class D) acceleration for a 1-Second Period SDs Five -percent damped design spectral response 0.954 g (Site Class D) acceleration for a Short Period SD1 Five -percent damped design spectral response 0.546 g (Site Class D) acceleration for a 1-Second Period 1. In general accordance with the 2015 International Building Code, Table 1613.5.2. IBC Site Class is based on the average characteristics of the upper 100 feet of the subsurface profile. 2. The borings completed for this study extended to a maximum depth of about 40 feet below grade. ZGA therefore determined the Site Class assuming that similar density soils extend to 100 feet as suggested by published geologic maps for the project area. Ground Surface Rupture: Based on our review of the USGS Quaternary age fault database for Washington State, the Southern Whidbey Island Fault Zone is located approximately 2 % miles southwest of the site. As the fault zone does not appear to cross the site, it is our opinion that the risk of ground surface rupture at the site is low. Landsliding: Based on subsurface soil and groundwater conditions observed in our explorations and the gently sloping topography of the site and surrounding vicinity, it is our opinion that the risk of earthquake - induced landsliding is low. Soil Liquefaction: Liquefaction is a phenomenon wherein cohesionless soils below the groundwater table build up excess pore water pressures during earthquake loading. Liquefaction typically occurs in loose, cohesionless soils, but may occur in denser soils if the ground shaking is sufficiently strong. The potential hazardous impacts of liquefaction include liquefaction -induced settlement and lateral spreading. Soil conditions observed in our explorations generally consisted of silty sands with no groundwater. The soils observed in our explorations are not susceptible to liquefaction. Stormwater Infiltration Feasibility As part of our services, we evaluated the feasibility of stormwater infiltration. Soil conditions observed in borings B-1 through B-3 form the basis of our opinion regarding infiltration feasibility. Soil conditions observed in these borings generally consisted of medium dense to dense fill soils. The introduction of concentrated volumes of water into fill soils through stormwater infiltration facilities at this site could lead to consolidation of the fill soils in a similar manor commonly referred to as "hydraulic compaction". Page 5