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5.4.5 Mine Area Stability <br />Documentation of mine wall stability has occurred in previous submittals for the Cresson <br />Project Mining has occurred for the last 15 years to depths of greater than approximately <br />800 feet and at designed slope angles without any observable slope failures other than <br />occasional bench raveling. <br />Call & Nicolas, Inc. ( "CNI ") performed a mine area slope design study for the mining <br />areas associated with MLE2. The key purposes of the study were to determine optimum <br />interramp slope angles and bench design parameters for MLE2 mine areas designs and <br />provide recommendations for slope management over the life of the Cresson Project. <br />The CNI study was based on the mine area design review and focused on both interramp <br />and overall slope angles and rock type expected for locations within the mine areas. <br />Additional details on the overall analysis as well as the interramp stability analysis can be <br />found in Appendix 6, Volume III. Only the overall slope stability is summarized in this <br />discussion. <br />Overall slopes were evaluated using the slope stability computer program SLOPE /W©, <br />which implements the limit - equilibrium method of slices. Ten cross sections were <br />selected for analysis of the stability of overall slopes based on wall height, overall slope <br />angle, and rock quality determination ( "RQD "). These sections included two in the Main <br />Cresson Mine area; one in the South Cresson portion of the Main Cresson Mine area; <br />four sections in the Globe Hill portion of the North Cresson Mine area; two in the Schist <br />Island portion of the North Cresson Mine area; and one in the WHEX portion of the East <br />Cresson Mine area. Locations of the evaluated cross sections can be found in Appendix <br />6, Volume III. CNI considers a factor of safety ( "FOS ") above 1.20 appropriate for final <br />mine wall slopes. The stability analysis showed that all sections evaluated were stable <br />except for Section GH -2 in the south end of the Globe Hill Mine area (see Table 5 -6). <br />This is likely due to the poor quality rock in the south end of the Globe Hill Mine area <br />and can be corrected by changing the interramp angle during mining from the currently <br />designed 52 degrees to 45 degrees. CC &V is committed to achieving overall stability <br />and will implement the recommended change. <br />Cripple Creek & Victor Gold Mining Company <br />Cresson Project Mine Life Extension 2 <br />5 -14 <br />Table 5 -6 Summary of MLE2 Overall Stability Analysis <br />Cross <br />Section <br />Current <br />Current Interramp Interramp Wall Assumed <br />Overall Slope Slope Angle Height (ft) RQD <br />Angle Angle Run <br />Factor of Safety <br />Mean <br />Strengths <br />-1 Std. <br />Dev. <br />Strengths <br />Cres — 1 <br />48° <br />60° <br />60° <br />1790 <br />70% 1.91 <br />1.6 <br />Cres — 2 <br />46° <br />57° <br />57° <br />1100 <br />40% 1.42 <br />1.29 <br />5.4.5 Mine Area Stability <br />Documentation of mine wall stability has occurred in previous submittals for the Cresson <br />Project Mining has occurred for the last 15 years to depths of greater than approximately <br />800 feet and at designed slope angles without any observable slope failures other than <br />occasional bench raveling. <br />Call & Nicolas, Inc. ( "CNI ") performed a mine area slope design study for the mining <br />areas associated with MLE2. The key purposes of the study were to determine optimum <br />interramp slope angles and bench design parameters for MLE2 mine areas designs and <br />provide recommendations for slope management over the life of the Cresson Project. <br />The CNI study was based on the mine area design review and focused on both interramp <br />and overall slope angles and rock type expected for locations within the mine areas. <br />Additional details on the overall analysis as well as the interramp stability analysis can be <br />found in Appendix 6, Volume III. Only the overall slope stability is summarized in this <br />discussion. <br />Overall slopes were evaluated using the slope stability computer program SLOPE /W©, <br />which implements the limit - equilibrium method of slices. Ten cross sections were <br />selected for analysis of the stability of overall slopes based on wall height, overall slope <br />angle, and rock quality determination ( "RQD "). These sections included two in the Main <br />Cresson Mine area; one in the South Cresson portion of the Main Cresson Mine area; <br />four sections in the Globe Hill portion of the North Cresson Mine area; two in the Schist <br />Island portion of the North Cresson Mine area; and one in the WHEX portion of the East <br />Cresson Mine area. Locations of the evaluated cross sections can be found in Appendix <br />6, Volume III. CNI considers a factor of safety ( "FOS ") above 1.20 appropriate for final <br />mine wall slopes. The stability analysis showed that all sections evaluated were stable <br />except for Section GH -2 in the south end of the Globe Hill Mine area (see Table 5 -6). <br />This is likely due to the poor quality rock in the south end of the Globe Hill Mine area <br />and can be corrected by changing the interramp angle during mining from the currently <br />designed 52 degrees to 45 degrees. CC &V is committed to achieving overall stability <br />and will implement the recommended change. <br />Cripple Creek & Victor Gold Mining Company <br />Cresson Project Mine Life Extension 2 <br />5 -14 <br />