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0 APPENDIX E <br />SLOPE STABILITY ANALYSES <br />1.0 GENERAL <br />The stability of the proposed expanded Forward Landfill facility was evaluated by <br />Geologic Associates (GLA) based on development plans prepared by BAS and <br />available information regarding likely refuse, soils, and liner materials. As required in <br />CCR Title 27, the analyses addressed both the surficial stability of final cover soils and <br />the gross stability of the planned landfill expansion. The analyses considered static and <br />pseudo -static loading conditions, and included evaluation of the seismic displacement <br />that could occur that could occur under earthquake loads. <br />2.0 SEISMICITY <br />An assessment of the seismic exposure for the Forward Landfill site was completed by <br />Geosyntec Consultants (2001) and is attached herein. Based on that assessment, two <br />potential earthquake events were considered for design: a MCE of M. 7.9 associated <br />with the San Andreas Fault at a distance of about 70 miles; and a MW 6.7 earthquake <br />associated with the Great Valley Fault at a distance of about 21 miles. The following <br />parameters were used in the seismic slope stability evaluations: <br />San Andreas Fault Event- Magnitude (MW) - 7.9 <br />Peak Horizontal Bedrock Acceleration <br />- 0.09 g <br />Duration of Significant Shaking (D5-90 <br />- 45.4 sec <br />Great Valley Fault Event- Magnitude (MW) <br />-6.7 <br />Peak Horizontal Bedrock Acceleration <br />- 0.13 g <br />Duration of Significant Shaking (Ds -95) - <br />15.3 sec <br />3.0 GROSS STABILITY ANALYSES <br />3.1 Analytical Methods <br />The slope stability analyses for the planned landfill expansion were completed using the <br />computer program SLOPE/W (Geo -Slope, 1995). Analytical methods available in the <br />program include the Bishop method for circular failure modes, and the Spencer / <br />Morgenstern and Price methods for general failure modes for both block and non - <br />circular failure surfaces. The analysis computes factor of safety against failure using limit <br />equilibrium procedures. Input parameters required for the analysis include geometry of <br />the slope, unit weights and shear strengths (angle of internal friction and cohesion) of <br />various materials, and pore -water pressure conditions. <br />L:Allied\2000.193\Reports\finaljtd:Appendix E GLA:08/16/01 <br />