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• Mr. John Poulos <br />September 27, 1994 <br />Page 3 <br />• Bedrock -Mesa Verde Sandstone group, cohesion 2000 psf, <br />internal friction angle 45°, moist unit weight 150 pcf, saturated <br />unit weight 150 pcf. <br />The slope stability was evaluated using PCSTABL5. This computer program <br />was developed at Purdue University and uses the simplified Janbu or simplified <br />Bishop method of slices. It compares the forces resisting slope failure to forces which <br />cause slope failure along a specified failure surface. The analysis utilizes a limit <br />equilibrium procedure to calculate the factor of safety against failure. The input <br />information for the analyses includes, but is not limited to, slope geometry, <br />groundwater conditions, soil strengths, and loading conditions. <br />CONCLUSION <br />Results of the recalculated stability analysis for the profile is summarized as <br />• follows: <br />Original Condition New design Reclaimed <br />Profile D:D 1.65 1.68 1.85 <br />The results of the recalculated slope stability analysis show an overall increase <br />in the factors of safety for the fan bench. The factor of safety for the new slope <br />design is above the required 1.5 factor of safety as required by the Colorado Surface <br />Coal Mining Reclamation Act. <br />Sin e e b <br />C~ ;~/`/~ <br />Charles C. Rehn, P.E. <br />General Manager <br />Salt Lake City Branch <br />CCR/laj <br />• <br />~; "„ <br />~ •., <br />. a~~,;•.....• <br />~rdYla4l <br />~C~ <br />