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Results of Static and Pseuodostatic SIope Stability Analyses <br />For the section analyzed, the static factor of safety for slip surfaces through the liner <br />system varied between 1.79 and 3.43. The yield accelerations varied between 0.16g and <br />0.17g. Output from the stability analyses are attached. <br />Earthquake Modeling <br />The generally accepted seismic deformations under a design earthquake for the final <br />slopes of a composite -lined landfill are between 6 inches and 12 inches (Seed and <br />Bonaparte, 1992; Sharma and Lewis, 1994). An average seismic deformation of 12 <br />inches or less was used as the acceptance criterion for the stability of the final slopes of <br />the WW D-01. <br />Design Earthquake <br />GeoSyntec performed a seismic hazard analysis for the Forward Landfill. The seismic <br />hazard analysis is attached. Based on GeoSyntec's evaluation, the MCE is a magnitude <br />(M) of 7.9 on the San Andreas and a M of 6.7 on the Great Valley Fault. <br />GeoSyntec developed three time histories for the M=6.7 MCE and one time history for <br />the M=7.9 MCE. These time histories were used for the one-dimensional seismic <br />response analyses (i.e., SHAKE). To match the spectral content, GeoSyntec <br />recommended that the bedrock time histories for the M=6.7 MCE be adjusted to a <br />bedrock acceleration of 0.19g and the time history for the M=7.9 MCE be adjusted to a <br />bedrock acceleration of 0. l Og. <br />Seismic Response Analyses <br />The one-dimensional analysis was completed using the SHAKE computer program <br />(Schnabel et al., 1972; Sun, 1988; ldriss and Sun, 1992) to predict the response of the <br />landfill mass to the input base rock motions. The program uses the equivalent linear <br />method to model the seismic shaking of a deposit and predict seismic response. <br />Inputs for SHAKE include unit weight, shear -wave velocity, and shear modulus and <br />damping characteristics for each soil layer. Design earthquake motion is input as an <br />acceleration -versus -time record. The design earthquake time histories developed by <br />GeoSyntec were used for these analyses. <br />To model the dynamic response analysis of the East-West cross section, the following <br />columns were used: <br />• 80 feet of soil overlying bedrock/stiff soil. This column was used to calibrate the <br />shear wave velocities assumed for the soil. After the results at ground surface were <br />considered to be reasonable, refuse was modeled above the soil for the remaining <br />analyses. 0 <br />