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Because waste to be placed above the geotextile cushion is deep, maximum arching is <br /> anticipated,therefore, <br /> MFA =0.5 <br /> The FSCR depends on the mass per unit area of the geotextile cushion. Assuming a 16 oz/yci2 <br /> (540 g/m2) geotextile, <br /> FSCR = 1.2 <br /> Assume, a factor of safety of 2 for chemical and biological degradation, <br /> FSC13D =2.0 <br /> Substituting the above values in eq. 1, <br /> Pa„ow = 50+0.00045 540 Z 1 1 = 10,000kPa <br /> (0.00635) (1.0)(0.5)(0.5) (1.2)(2.0)_ <br /> Assuming a conservative maximum waste height of 200 feet in Module 1 and a waste unit <br /> weight of 65 pounds per cubic feet,the actual pressure(P.wa1) on the geotextile cushion is, <br /> Pa,.t,ai =(200 ft)x(65 lb/ft3)= 13,000 lb/ft2=625 kPa <br /> The factor of safety (FS)against puncture of the HDPE geomembrane is given by, <br /> FS = Pouow = I 0'000 = 16 <br /> Poc�aa� 625 <br /> Since the computed factor of safety is greater than the recommended (Koerner, 1998) minimum <br /> factor of safety of 3,the 16-ozlyd2 geotextile cushion (non-woven,needle-punched) is more than <br /> adequate to provide the necessary puncture protection. <br /> 3.0-Geotextile Cushion Interface Shear Strength <br /> The results of slope stability analyses for Module 1 were previously presented in a report entitled <br /> Static and Seismic Slope Stability Analysis, Foothill Sanitary Landfill, Module I <br /> (EMCON/OWT,July 2002). The results of that slope stability analyses show that Module 1 base <br /> N:\sacDP\2003\Frj\83\835608.3ap.doc <br /> (FSL) <br /> 3 <br />