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Novack ProperIT 99-11-10 <br />51" Place <br />Everett, Wa. <br />the Applied Technology Conference (ATC-6). The ground motion coefficients are <br />independent of structure type. <br />Soil type at a particular site affects the earthquake related motion characteristics of <br />damping. ATC-6 accounts for the influence of site specific soils by assigning a site <br />coefficient soil profile type. We recommend that the site be classified as soil profile <br />type II. Soil profile type II is assigned to sites underlain by stiff clay or deep <br />cohesionless soil in a stable condition and having a depth greater than 200 feet. Soil <br />type II, corresponding to a site coefficient (S) of 1.2, best fits the site conditions at <br />this location. <br />Liquefaction refers to a phenomenon in which a saturated, loose, cohesionless soil <br />looses strength during an earthquake. The loss of strength allows it to move <br />vertically and/or laterally. The potential for liquefaction is dependent upon several <br />factors: <br />• seismic intensities and duration of ground motion <br />• .soil moisture and pore pressure potential -only saturated soil will liquefy <br />• soil grain size - only.rne-grained sands and coarse silts are affected unless <br />very high pore pressures are created, then fine to medium dense gravels can be <br />affected <br />The site is located within the Puget Sound Lowland Physiographic Province, a <br />seismically susceptible region with historic occurrences of earthquakes and other <br />seismic actions. Documented liquefaction in the region has occurred in the river <br />valleys where normally consolidated alluvial soils and high ground water tables are <br />present. Due to the dense overconsolidated soils and the general lack of a ground <br />14 GES, Inc. <br />