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<br />METHODOLOGY <br /> <br /> <br />The embankment configuration shown in the computer analysis represents the proposed <br />reservoir liner which is a 16 foot high embankment with a 3:1 side slope. Material <br />properties where obtained from typical values for the onsite soils identified in the <br />geotechnicalreport. <br />Two methods were used in the computer analysis for determining safety factors; <br />Simplified Bishop's Procedure and JanBu procedure. Both procedures search for circular <br />shear failures and automatically search for the lowest safety factor. Both methods <br />converged on neazly identical safety factors in every case. The proposed minimum safety <br />factors are based on the current standards used by the State Engineer in evaluating <br />embankment dams. <br />SLOPE STABILITY RESULTS <br />The results of the slope stability analysis are presented in Table 2. The calculated factors <br />of safety are within the design criteria specified for this project and can be considered <br />indicators of the embankment performance under the various conditions. <br />Table 2. Slope Stability Analysis Results <br />Descri tion Factor of safet <br />Case 1 -Minin Conditions 1.43 <br />Case 2 -Minin Conditions 1.38 <br />Case 3 -Full reservoir 2.96 <br />Case 4 - Ra id Drawdown 1.90 <br />CONCLUSIONS AND RECCOMENDATIONS <br />1. The materials available onsite appear to be suitable for construction of the <br />proposed earth embankment. <br />2. The safety factor calculated for the mining conditions adjacent to the public roads <br />is 1.43 which exceeds the minimum requirement of 1.25. The proposed 35' <br />setback is adequate. <br />3. The safety factor calculated for the mining conditions adjacent to the Box Elder <br />Ditch is 1.38 which exceeds the minimum requirement of 1.25. The proposed 25' <br />setback from the top of the ditch bank is adequate. <br />4. The safety factor calculated fora full reservoir is 2.96 which exceeds the <br />minimum requirements of 1.5. This case assumes that the reservoir has been full <br />for an extended period of time causing the embankment to become saturated. <br />b <br />