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maintenance period. Included as part of the survey information, an iso- <br /> settlement map and report is to be submitted to the RWQCB. <br /> 3.5 LANDFILL SLOPE STABILITY <br /> A slope stability analysis is required by 27 CCR, Section 21090 when the <br /> closure design includes final slope faces steeper than 3:1 (horizontal to <br /> vertical) or a synthetic component in the final cover configuration. The <br /> proposed final slopes for the Forward Landfill do not exceed 3:1 and a <br /> synthetic component is not proposed, but the slope below the proposed 15- <br /> foot wide bench has an inclination of 2:1 (horizontal to vertical). Therefore, a <br /> slope stability analysis was conducted pursuant to 27 CCR, Section <br /> 21750(f)(5) to review the integrity of final slopes under both static and <br /> dynamic conditions. The results of the slope stability analysis are included in <br /> Appendix C. <br /> To evaluate the static stability of the proposed refuse cover system at various <br /> design inclinations and slope heights, the proposed cover configuration was <br /> Ankh analyzed by typical force equations. For this case, the soil cohesion was <br /> neglected. Static refuse cover slope stability (assuming a failure at the <br /> cover/MSW interface) for all three slope inclinations analyzed indicates a <br /> factor of safety greater than 1.5 <br /> To analyze the cover layer itself, the infinite slope method was utilized. This <br /> analysis assumes that the failure takes place within the soil cover itself. Two <br /> cases were analyzed: unsaturated and fully saturated. Static refuse cover <br /> slope stability for the steepest proposed slope inclination of 3.2:1 (horizontal <br /> to vertical) indicates an unsaturated factor of safety of 2.31 (typically has to <br /> be greater than 1.5) and a saturated factor of safety greater than 1.3 (typically <br /> a saturated factor of safety of 1.1 to 1.2 is adequate). <br /> The proposed 2:1 (horizontal to vertical) slope below the 15-foot wide <br /> benches was analyzed for static and dynamic stability by the use if the <br /> computer program SLOPE/W. The results of the static stability analysis <br /> indicate a factor of safety of 1.92. <br /> The three proposed cover inclinations and heights were analyzed for dynamic <br /> displacement. For analysis of the dynamic condition, the cover configuration <br /> Forward Landfill PFCPCMP 3-9 <br /> Z:\PROJECTS\Allied Waste\Forward\Reference Files Prior JTD\June 05 Stage IA Partial FCPCMP\FL-sec3.doc:6/16/2008 <br />