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Page 12 <br />June 3, 1992 <br />SAC31583.AC.ZZ <br />Table 2 <br />Summary of Static Safety Factors <br />Long-term Final <br />Refuse Buildout <br />Section <br />Failure Type (see plots, Appendix C) <br />Static Safety Factor <br />CS -A <br />Block -type failure along smooth FML liner interface <br />1.3 <br />Block -type failure along textured FML liner interface, unsaturated <br />3.0 <br />Block -type failure along textured FML liner interface, saturated <br />1.6 <br />Circular -type failure search <br />2.4 <br />Block -type failure along 2,300 psf shear strength layer (lean clay <br />layer between elevation 0 and 10 feet) <br />2.3 <br />CS -B <br />Block -type failure along smooth FML liner and/or along 2,000 psf <br />shear shear strength compacted clay Iiner in WMU E area <br />2.0 <br />Block -type failure along textured, unsaturated FML liner and/or <br />along 2,000 psf shear strength compacted clay liner in WMU E area <br />2.0 <br />Block -type failure along textured, saturated FML liner and/or along <br />2,000 psf shear strength compacted clay liner in WMU E area <br />2.0 <br />Circular -type failure search <br />1.8 <br />Block -type failure along 2,300 psf shear strength layer (lean clay <br />layer between elevation 0 and 10 feet) <br />2.2 <br />As shown in Table 2, a static safety factor of 1.3 was estimated for a smooth FML liner <br />assuming an interface friction angle of 8 degrees, which is less than the recommended <br />minimum safety factor of 1.5 for long-term final buildout conditions. For a textured FML <br />liner, a static safety factor of 1.6 was estimated assuming saturated conditions with a friction <br />angle of 9 degrees and a cohesion of 420 psf. Based on results of these preliminary analyses, <br />we recommend that a textured FML liner be used for the proposed landfill extension. <br />Assuming that a textured FML liner is used, the analyses indicate the cross sections meet the <br />static stability design criteria for final buildout of the proposed landfill extension. The shear <br />strength of the textured FML/clay lining interface should be determined by laboratory and/or <br />field testing to confirm that the assumed textured FMUclay interface friction angle shown in <br />Table 1 is feasible. <br />Results of Seismic Stability Analyses <br />A yield acceleration of 0.148 was estimated for the block -type failure along the textured <br />FML liner (saturated conditions) for Section CS -A. As previously discussed, the estimated <br />1-1 <br />