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Table 4 Stability Analysis Results <br />Notes <br />1) A pseudo -static horizontal seismic acceleration of 0.0698g was used in modeling. <br />The model outputs for these stability runs are shown in Figures 8 through 13. It can be seen that the <br />static factors of safety are a substantial improvement over the failed case in which the factor of safety <br />is presumed to be close to unity. Furthermore, the seismic factors of safety are all above unity or very <br />close to unity. <br />The stability modeling has been completed for what is considered to be the "worst case" section <br />along the slope. While the seismic analysis indicates that the factor of safety is 0.98 for the worst <br />case, this assumes the shear strength of the soils in the slope exhibit the saturated shear strength at <br />the time a seismic event occurs. The combination of these two conditions is unlikely. Other seismic <br />analyses indicate a factor of safety greater than 1.0. <br />The factor of safety has been increased from something equal to or less than 1 for the native slopes <br />(as evidenced by the slides), to 1.25 if USSA conditions are applied, or 1.36 for ESSA conditions if <br />matric suction is assumed. It is only when matric suction is ignored that the model indicates the <br />factor of safety would drop to as low as 1.1. Given that the USSA case (FS=1.25) no longer applies <br />because the fill has already been placed as part of the slope repair process, the 1.36 factor of safety <br />for the ESSA case is shown to be above the minimum required 1.3 value and should be taken as the <br />"minimum static safety factor." <br />2.4.3 Recommendations <br />Repaired haul road HR -1 slide slopes should be monitored as described in the next section of this <br />report. If slope movement is noted, several measures are available to increase the factor of safety. <br />Such measures include: <br />• Constructing a trench drain along the haul road to improve dewatering of the slope <br />• Buttressing the toe of the slope, in conjunction with extending the drainage blanket on the <br />lower bedrock bench <br />P:\Mpls\06 CO\26\06261003 Haul Road Slide Repair\WorkFiles\Report\MCC_Slump_Repair-Instrumentation-Dram Rev 2012-12-12.docx 10 <br />