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6.3.5 South Quarry <br /> The South Quarry highwall was analyzed using the rock mass properties defined in Section <br /> 6.3.4 and slope geometry based on Figure 6 with vertical highwall faces. For the global <br /> stability case, the entire highwall was considered as potential a failure surface for the critical <br /> slip surface. For the intra-bench highwall case, the critical slip surface was limited to a range <br /> of three (3)benches above the intermediate bench and three (3) benches below the bench <br /> location. Additional sensitivity models of the South Quarry models included the presence of <br /> sillimanitic gneiss, based on the 3D Model developed by GEI as presented in Appendix B. <br /> The two intermediate bench configurations consist of a 30, 40, 50, or 100-foot wide bench at <br /> El. 7,000 and a 30, 50, 60, or 100-foot wide bench at El. 6,650 feet. Local stability properties <br /> were used in evaluating the recommended bench widths. <br /> 6.3.6 West Quarry <br /> The West Quarry highwall was analyzed using the rock mass properties defined in Section <br /> 6.3.4 and slope geometry based on Figure 6-1 with vertical highwall faces. The two highwall <br /> sections encompass (1)the east facing West Quarry highwall and(2) the west facing West <br /> Quarry highwall. Additional sensitivity models of the West Quarry models included the <br /> presence of sillimanitic gneiss, based on the 3D Model developed by GEI as presented in <br /> Appendix B. <br /> 31 <br /> Aggregate Industries—Morrison Quarry GEI Consultants, Inc. <br /> AM-07 Geotechnical Stability Exhibit November 2020 <br />