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Table 1: DRMS Model Parameters <br />Soil Type <br />Effective <br />Friction Angle <br />q1' (degrees) <br />Effective <br />Cohesion <br />c' (psf) <br />Saturated Unit <br />Weight <br />Aar (Pc ) <br />Overburden <br />28 <br />50 <br />126 <br />Gravel <br />35 <br />0 <br />137 <br />Weathered Bedrock <br />14 <br />0 <br />142 <br />Bedrock <br />28 <br />100 <br />142 <br />In our opinion, the parameters for weathered bedrock are very conservative based on the conditions <br />typically encountered in the project area. <br />In accordance with the DRMS guidelines, we analyzed a vertical highwall section. The vertical section <br />corresponds to a steep highwall mining scenario where the highwall inclination is approximately 0.5:1 <br />(horizontal to vertical). The depth to bedrock varied from 311/2 to 51 feet across the project site. <br />Table 2 below summarizes the results of our analysis. The analysis was performed using the DRMS <br />parameters shown in Table 1. The factor of safety required by the DRMS for temporary mine slopes <br />and reservoir embankments are provided for comparison. Output graphics for each of the analyses are <br />attached. <br />Table 2: Hihwall Setback DRMS Analysis Results <br />Model <br />Setback <br />Distance (feet) <br />Calculated <br />Factor <br />S fetJ°f <br />Required Factor <br />of Safety <br />Adjacent to Brighton Road <br />50 <br />1.17 <br />1.0 <br />Adjacent to Spier Property <br />45 <br />1.14 <br />1.0 <br />Near McCanne Ditch <br />65 <br />1.08 <br />1.0 <br />The required setback distance provided in Table 2 is calculated from the crest of the mine highwall to <br />the potential failure surface intersection with the existing ground surface. <br />P 0377 Hart Ens tronmental Bromley Lakes Stability Analysts Stability Exhibit Btom ley Lake Stability Exhibit doc <br />Bromley Lakes <br />DRMS 112 Permit <br />Page SE2 of SE2 <br />