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November 29,2016 <br /> Project No.T-5922-6 <br /> 4.3- Seismic Hazards <br /> We reviewed the criteria for seismic/liquefaction hazard areas contained in Section 19:37.080A.2. of the City of <br /> Everett Municipal Code (EMC). The site is located in an area mapped on the City of Everett— Critical Areas <br /> Map 5, Liquefaction Susceptibility Map of Snohomish County, Washington (2004) as having very low <br /> susceptibility to soil liquefaction. <br /> Liquefaction is a phenomenon where there is a reduction or complete loss of soil strength due to an increase in <br /> water pressure induced by vibrations. Liquefaction mainly affects geologically recent deposits of fine-grained <br /> sands below the groundwater table. Based on the presence of dense, glacially consolidated soils at the site, it is <br /> our opinion that the risk for damage resulting from earthquake-induced slope failure or soil liquefaction is <br /> negligible. Therefore, in our opinion, unusual seismic hazard areas do not exist at the site, and design in <br /> accordance with local building codes for determining seismic forces would adequately mitigate impacts <br /> associated with ground shaking. <br /> Based on our on-site observations, exploration, and document review, it is our opinion,the site does not meet the <br /> criteria of a seismic hazard area as defined by the EMC. <br /> 4,4 Seismic Design Parameters <br /> Based on the soil conditions encountered and the local geology,the 2015 InternationalBuilding Code (IBC) <br /> indicates that site class"C"should be used in structural design. <br /> Seismic Design Parameters(IBC 2015) <br /> Spectral response acceleration(Short Period), SMs, 1.445 g <br /> Spectral response acceleration(1 -Second Period), SM1 0.719 g <br /> Five percent damped 0.2-second period, SDS 0`.964 g <br /> Five percent damped 1-second period,SDI 0.479 g <br /> These values were determined using the Latitude 47.94445°N and Longitude -122.26483°W, and were obtained <br /> from United States Geologic Service (USGS) Ground Motion Parameter Calculator (accessed November 17, <br /> 2016). <br /> 5.0 DISCUSSION AND RECOMMENDATIONS <br /> 5.1 General <br /> Based on our study, there are no geotechnical conditions that would preclude the planned development. The <br /> classroom building and retaining wall can be supported on conventional spread footings bearing on the existing <br /> inorganic medium dense fill soils or dense Advance outwash sands. <br /> Page No.4 <br />