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again an active wedge resting above a passive wedge that is at the toe of the slope. The equations developed by Koerner and Soong take into account all necessary parameters to perform a pseudo-static stability analysis. Yield acceleration was determined for the cover section if the pseudo-static FS < 1.5 • An assessment of the potential for permanent displacement during the design earthquake based on a comparison of the PGA and yield acceleration for cross sections with pseudo-static factors of safety < 1.5 using the method from Makdisi and Seed (1978) ' 3. MATERIAL PARAMETERS 3.1 Orientation and Strength of Landfill Cap Components The cap extension for the Landfill has been designed utilizing the following items listed in ascending order: 1.0 foot of prepared subgrade • 60-mil double-sided textured LLDPE • 200-mil geocomposite drainage net(GDN)(HDPE core with non-woven polyester or polypropylene geotextile on either side) • 1.0 foot of earthfill • 1.0 foot of vegetative cover soil The soils on site that are anticipated to be used to construct the earthfill, vegetative cover and prepared subgrade have been assumed to be poorly graded sands to silty sands having no cohesion and an internal angle of friction of 32 degrees. To establish a lower limit strength requirement for the landfill cap, the minimum interface friction angle was solved for using the previously noted stability equations. 3.2 Slope Stability Analysis for Static Conditions The slope analyzed for stability is referenced in Section 1.1 above and is shown in Figure 1. As can be seen in the stability analysis presented in Calculation 1,to obtain a minimum factor of safety of 1.5, an interface friction angle of 21.0 degrees is required. The minimum interface friction angle applies to any of the components within the landfill cap system, although it is anticipated that the weakest interface will be the textured LLDPElsoil interface at the bottom of the liner section. It is worth noting that the stability of the soil veneer was not analyzed in a saturated ' condition because an adequate drainage layer has been designed to be incorporated into the cover liner system over the impermeable geomembrane. The GDN is the drainage layer, which is designed to allow water to rapidly migrate out of the cover section and thereby reduce the presence of pore water and its detrimental effects. According to Othman et al. (1995), if an effective drainage layer is incorporated into the cover system, the effects of water flow above the geomembrane can be considered negligible, and a stability analysis only considering the drained condition of the slope is adequate. Slope Stability Analysis Corral Hollow Landfill 4151202 4