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Using these conditions, the failure slopes for the final mining and reclaimed slopes were determined <br /> using Bishop's Method of Slices to identify the circular failure at various factors of safety (FOS). The <br /> results are summarized Table 3 and a set of GALENA outputs are attached with more detailed <br /> information. <br /> Table 3—Slope Stability Analysis Results <br /> Distance from FOS <br /> Lowest Failure Circle to Sufficiency <br /> Analyzed Slope Status Slope <br /> Calc.FOS Nearest Structure (Y/N) <br /> (ft) <br /> Active Mining 1.25H:1V 1.34 —50 ft N* <br /> *Active Mining FOS=1.5 1.25H:1V 1.50 —47 ft Y <br /> Final Reclaimed 3H:1V 1.74 1 "50 ft Y <br /> 3. Conclusion <br /> The final mining slopes have a maximum slope of 1.25H:1V and reclaimed slopes are proposed to <br /> be 3H:1V. An analysis of these slopes resulted in factors of safety as outlined in Table 3. <br /> The Active Mining slope analysis produces a final factor of safety of 1.34, which is less than the 1.5 <br /> required by CDRMS for slope stability near critical structures using general material properties. <br /> Therefore, a secondary analysis was conducted to find the factor of safety failure circle where the <br /> factor of safety was 1.5. The failure circle at the Factor of Safety of 1.5 daylights roughly 47 feet <br /> from the nearest structure, which is assumed to be a gas or electric line. The distance from the <br /> failure circle to the structure shows that the structure will not be damaged during mining. <br /> Maintaining the excavation setback at 50-ft is recommended. <br /> The Final Reclaimed slope generates a factor of safety more than sufficient to meet CDRMS <br /> standards regarding slope stability using general material properties (1.5). Additionally, this circular <br /> failure scenario was contained entirely on the reclaimed slope face. Therefore, the permanent slope <br /> conditions following mine reclamation pose no risk of failure outside the property or to any nearby <br /> structures. <br /> dr <br /> • <br /> �� �1• <br /> •,I�/ �•:�7/17/2V.1 <br /> ll�hit%S/ONA\- <br /> Ben Langenfeld, P.E. #47151 <br /> Kattenberg Pit Slope <br /> Stability 3 Lewicki& Associates <br /> ember 202 <br />