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was iteratively solved for various horizontal ground accelerations for a factor <br /> of safety of 1.0. Seismically induced permanent displacement was estimated <br /> using procedures described by Bray and Rathje (1998) and Bray et. al. <br /> (1998), which account for the failure wedge height, yield acceleration (ky), <br /> MHA, shear wave velocity of the waste, the period of the waste, period of the <br /> earthquake waves, an empirical non-linear response factor, and the duration <br /> of shaking. Based on the site specific earthquake response factors, a <br /> Maximum Horizontal Equivalent Acceleration (MHEA) is calculated and <br /> compared to the yield acceleration. If the MHEA is greater than the yield <br /> acceleration, then earthquake-induced displacement is indicated. If the yield <br /> acceleration is greater than the MHEA, then earthquake-induced <br /> displacement is not likely to occur. The ky value was then used to estimate <br /> dynamic displacement of the cover under dynamic conditions using the Bray <br /> and Rathje (1998) method, as necessary. <br /> The results of the analysis indicate that the calculated dynamic displacement <br /> of the landfill cover in less than 1 inch. The calculated displacement is <br /> significantly less than the 6 to 12 inches generally considered to be the <br /> maximum movement that a landfill cover system can accommodate without <br /> compromising the integrity of a landfill's environmental control systems (Seed <br /> and Bonaparte, 1992). <br /> The dynamic stability of the 2:1 slope below the proposed benches was also <br /> evaluated. To evaluate the dynamic response to the MHA event, a pseudo- <br /> static analysis was performed to solve for the horizontal site acceleration that <br /> would cause a factor of safety of 1.0. The acceleration was 0.348. The slope <br /> was then analyzed for permanent dynamic displacement in accordance with <br /> the procedures described above by Bray and Rathje (1998) and Bray et. al. <br /> (1998). No dynamic displacement was calculated for this slope. <br /> In summary, the seismic stability analyses indicate that the earth-induced <br /> displacement of the landfill cover and 2:1 slope below the proposed 15-foot <br /> wide bench will be negligible under MCE loads. <br /> Forward Landfill PFCPCMP 3-10 <br /> Z:\PROJECTS\Allied Waste\Forward\Reference Files Prior JTDUune 05 Stage IA Partial FCPCMP\FL-sec3.doc:6/16/2008 <br />