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Material <br />Moist Unit <br />Weight (pcf) <br />Saturated Unit <br />Weight (pcf) <br />Effective Cohesion <br />(pcf) <br />Effective Friction <br />Angle (degrees) <br />Overburden clay <br />114 <br />126 <br />150 <br />28 <br />Sand and gravel <br />130 <br />137 <br />0 <br />37 <br />Clay Lense <br />116 <br />119 <br />200 <br />22 <br />Weathered Residual <br />Strength Bedrock <br />124 <br />134 <br />0 <br />. <br />14 <br />Claystone Bedrock <br />124 <br />134 <br />500 <br />22 <br />STABILITY ANALYSES <br />Stability analyses were performed in order to evaluate potential for damage to existing permanent <br />structures due to mine highwall slope failures. Analyses were performed with the Slope -W 2007 <br />computer program. For each case we analyzed the most critical soil profile(s) based on exploratory <br />boring data (i.e. the tallest highwall, thickest overburden layer, and associated weaker clay lenses). <br />The stability analyses were run in accordance with accepted geotechnical standards and DRMS <br />requirements for temporary pit slopes summarized as follows: <br />Groundwater levels on the profiles were input to portray site dewatering. <br />No laboratory strength tests were performed on soils at the site. The soil strength parameters used <br />were based on typical values for the anticipated soils and our experience working with DRMS at <br />other sites in the area. The input strength parameters were: <br />• Mine highwalls modeled as vertical slopes <br />• Residual soil strength parameters used for the upper 2.5 feet of weathered bedrock <br />• Factor of Safety must be greater than 1.0 <br />