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STABILITY ANALYSIS WMU FU-17 FORWARD LANDFILL PROBLEM: Assess the static stability of the refuse over the lining system for WMU FU-17 at the Forward Landfill. Because WMU FU-17 is an interior module,there are no slopes on this module that will coincide with the final landfill grades. Seismic analyses are,therefore,not required. In addition,although there is a small lined area on the slope of the northwestern portion of the cell,refuse fill will overlie only a minor portion of this slope due to the geometry of the 3:1 northern refuse slope. Stability analyses on the interface liner on the northwest slope are,therefore,not required at this time. 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-17 is similar to WMUs FU-03, ART-03,FU-04, FU-05,FU-06, FU-08,FU-10,FU-13,FU-14 and various other WMUs at the site. SUMMARY: 1. The planned maximum elevation of refuse in WMU FU-17,prior to the development of adjacent waste management units, is 170 ft MSL.This elevation is based on 3:1 slopes on the south and east. The west slope will be filled against the existing WMU FU-13 and 14 refuse slopes. 2. Development is planned to the east of WMU FU-14. In addition,the northern and southern boundaries are not extended to their full length to allow access to the wedge area on the south and a potential expansion to the north.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 interim filling configuration (refuse fill elevation 170 ft)is in the E-W direction along the base liner. 2. For interim slopes,a static factor of safety of 1.3 is typically considered acceptable. SUMMARY OF STABILITY ANALYSIS RESULTS 1. The minimum factor of safety for WMU FU-17 under the planned interim fill configuration(refuse elev. 170 ft)is 1.57. The critical failure surface extends from approximately the crest of refuse, through the refuse mass,and then along a portion of the base liner,daylighting at the toe of slope. 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. 2. The stability analysis assumes the base liner interface shear strengths between the clay and textured HDPE are a friction angle of 18 degrees and an apparent cohesion of 0 psf and a friction angle of 10 degrees and an apparent cohesion of 1,000 psf for normal load ranges from 0 to 6,500 psf and from 6,500 to 17,000 psf,respectively. The base liner interface strength between the cushion geotextile and the textured HDPE geomembrane is as follows: Normal Stress sf) Minimum Shear Stress(psf) 2,000 700 4,000 1,110 8,000 1,950 12,000 2,780