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where F91"" is the factor of safety from the global analysis as presented in Table 5 and Table <br /> 7. These lower strength material properties provide a basis for assessment of the margin of <br /> stability for the global model. The results of these analyses are shown in Table 6 and in <br /> Figures 13-17 through B-26 and C-19 through C-28. <br /> 5.2.1 SLOPEM <br /> In general, SLOPE/W estimated higher factors of safety than FLAC/Slope. This was likely <br /> due to the constraints put on the slip surface entry and exit locations. In SLOPE/W, the slip <br /> surfaces were defined to enter from the top of the slope and exit through the bottom, going <br /> through the entire height of the highwall or considered region. When the entire highwall was <br /> analyzed with global properties, the factors of safety were consistently above 4.20 for all <br /> bench configurations presented in Table 5. For the regional models with weaker global <br /> properties, the factors of safety ranged from 1.29 to 1.54 for the presented bench <br /> configurations. <br /> For analyses where failure was considered below El. 7000 through the 70-foot high benches <br /> using the global properties, SLOPE/W was unable to calculate realistic factors of safety. <br /> Using the material properties derived from shear strength testing and considering three <br /> benches below El. 7000, the calculated factor of safety was well above stability criteria and <br /> greater than 3.60. For analyses that considered a stability bench at El. 6650 (Cases 15 <br /> through 18), SLOPE/W estimated factors of safety that were adequate for stability for both <br /> global and weaker regional properties used. <br /> Using the strength reduction method to provide a basis for assessment of the margin of <br /> stability, the safety factors from the initial global models (Cases 1, 3, 5, and 7) were used to <br /> estimate lower strength properties. The resulting strength properties from this method were <br /> approximately 33% of the strength of initial global strength properties and were used for <br /> Analysis Cases 1-1, 3-1, 5-1, 7-1, and 11-1. The factors of safety when these properties were <br /> modeled were approximately 1.40. <br /> The factors of safety from the initial global models analyzed in FLAC/Slope were also used <br /> to estimate lower strength properties. These properties were used for Analysis Cases 1-2, 3- <br /> 2, 5-2, 7-2, and 11-2 and analyzed in SLOPE/W. Because FLAC/Slope typically estimated <br /> lower safety factors, the resulting reduced strengths were approximately 3 8%of the initial <br /> global properties. The safety factors calculated by SLOPE/W from these reduced strengths <br /> were approximately 1.60. <br /> Aggregate Industries Morrison Quarry GEI Consultants, Inc. <br /> South Quarry Highwall Design Technical Revision 22 August 2017 <br />