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WMU FU-10 Interim Fill Condition As shown on the Construction Drawings (Appendix A), WMU FU-10 is directly south of the former Austin Road Landfill and directly east of WMU FU-08. The southern boundary is offset from the main access road. The site development plan(BAS,2001)includes development of future modules to the east of WMU FU-10. The slope stability analysis was performed for an interim refuse fill elevation of 150-ft with a 3:1 slope. The critical slope configuration is in the east-west direction. Other sections were considered but assessed to be less critical. As indicated in Appendix B, a minimum factor of safety of 1.6 is obtained for a sliding block shear surface along the base liner and through the refuse in the east-west direction. A factory of safety of 1.6 is acceptable for the temporary east-west slope. The maximum refuse fill height and slope for WMU FU-10 should be re-evaluated based on actual CQA direct shear tests results on the base and slope liner interfaces. Because the east slope of WMU FU-10 is a temporary slope, a seismic deformation analysis was not performed. Forward Landfill Final Grades As shown on the Construction Drawings (Appendix A), WMU FU-10 is directly south of the former Austin Road Landfill and directly east of WMU FU-08. The southern boundary is offset from the main access road. The site development plan(BAS,2001)includes development of future modules to the east of WMU FU-10. The slope stability analysis was performed for a maximum Forward Landfill refuse fill elevation of 200-ft for a NE to SW section running along the intersection of the south and west facing final refuse fill slopes. The effective slope is approximately 4:1. As indicated in Appendix B, a minimum factor of safety of 2.0 is obtained for a sliding block shear surface along the base liner and through the refuse in the NE-SW direction for the effective 4:1 final slope. A factory of safety of 2 is acceptable for permanent slopes. The maximum refuse fill height and slope for WMU FU-10 should be re-evaluated based on actual CQA direct shear tests results on the base and slope liner interfaces. Because the NE-SW slope of WMU FU-10 is a permanent slope, a seismic deformation analysis was performed. The SHAKE computer program was used to predict the response of the landfill to the input base rock motions. To model the dynamic response of the critical cross section,the following columns were used: • 80-feet of soil overlying stiff soils/bedrock. This column was used to calibrate the shear wave velocities assumed for the soil. After the results at ground surface were considered to be reasonable,the refuse was modeled above the soils for the remaining analysis. • 70 and 140 feet of refuse overlying 80 feet of soil overlying stiff soils/bedrock. The accelerations at the ground surface for the soil-only column varied between 0.14g(for Mw 7.9 time history)and 0.21 g(for Mw 6.7 time histories). The accelerations at the ground surface for the refuse-soil column varied between 0.14g and 0.15g(for Mw 7.9 time history)and between 0.208 and 0.30g(for Mw 6.7 time histories). The ground accelerations at the top of the soil-refuse columns were equated to fl.in the Makdisi and Seed(1977)procedure to estimate deformations.The yield acceleration for the critical section is 0.185g. WMU FU-10 REPORT 3-