Laserfiche WebLink
11 <br />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 JTD\June 05 Stage IA Partial FCPCMP\FL-sec3.doc: 6/16/2008 <br />