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STATIC AND SEISMIC STABILITY ANALYSIS WMU FU-08,FORWARD LANDFILL PROBLEM: Assess the static and seismic stability of the refuse over the base and side slope lining system for WMU FU-08 at the Forward Landfill. GIVEN: These calculations have been previously performed for the prior WMUs at the site and they have been found to have a satisfactory factor of safety and seismic deformation. The analysis for WMU FU-08 is similar to WMUs FU-03,ART-03,FU-04,FU-05,FU-06 and various other WMUs at the site. SUMMARY: 1. According to the site development'and final grading plans for the site,the maximum planned elevation of refuse for the landfill in the WMU FU-08 area is 195 ft MSL. This elevation occurs at the intersection of the south and west facing final fill slopes along a NE to SW cross section. The effective slope through this section is approximately 5:1. The 195 ft elevation may only be achieved if waste placement occurs in adjacent waste management units. 2. The planned maximum elevation of refuse in WMU FU-08,prior to the development of adjacent waste management units,is 150 ft MSL.This elevation is based on 3:1 slopes on the south and east. The west slope is filled against an existing refuse slope. The north slope continues the existing northern slope of the former Austin Road Landfill. 3. Development is planned to the east and south of WMU FU-08. These slopes are,therefore,temporary and will eventually be buttressed by adjacent slopes. STABILITY ANALYSIS SECTIONS AND CRITERIA: 1. The critical cross section for the stability analysis under the maximum filling configuration(refuse fill elevation 195 ft)is in the NE-SW direction. 2. The acceptable static factor of safety is 1.5 for permanent slopes. For interim slopes,a static factor of safety of 1.2 to 1.3 is acceptable. 3. For seismic analyses,acceptable deformations are less than 1-foot. SUMMARY OF STABILITY ANALYSIS RESULTS 1. The minimum factor of safety under the Forward Landfill maximum fill configuration(refuse elev. 195 ft)is 2.1. The critical failure surface extends from the lowest bench,through the refuse mass,and then along the base(cuhion geotextile/HDPE)and slope liner. Failure surfaces extending along the base liner and through the northern interface liner slope were also searched but found to be less critical. From the seismic analysis,the anticipated amount of deformation is less than 1-inch. 2. The minimum factor of safety for the southern portion of WMU FU-08 under the planned maximum fill configuration(refuse elev. 150 ft)is 1.6. The critical failure surface extends from approximately the crest of refuse,through the refuse mass,and then along the base liner. Both the base liner ® interfaces(clay/HDPE and cushion geotextile/HDPE)were analyzed but the cushion geotextile/HDPE condition was found to be more critical.