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7.2.1 Material Properties <br /> Material properties used for the stability analyses were derived from the rock-strength <br /> testing and characterization performed on drill core samples combined with the amount of <br /> rockmass fracturing estimated from the RQD block model. A detailed explanation of the <br /> determination of these strength parameters is presented in Chapter 4.0. Rock-mass properties <br /> used in the analyses are summarized in Table 7-1. Rock-mass strengths for this analysis are <br /> considered post peak strengths, and are therefore suitable for long term design. <br /> 7.2.2 Hydrology <br /> Water pressures in the slopes for the overall stability analysis are assumed to be drained <br /> and unsaturated. Pore-water pressures are assumed to be dissipated into existing underground <br /> workings below the mines. <br /> 7.2.3 Selection of Cross Sections for Analysis <br /> Ten cross sections were cut perpendicular to the March 2011 MLE2 final mine area shells <br /> provided by CC&V at the time of analysis. These cross sections are presented on the plan maps <br /> in Figures 7-1 thru 7-4. These cross sections were selected based on the following criteria: <br /> • Overall slope height <br /> • Overall slope angle (OSA) <br /> • Rock-mass strength <br /> 7.2.4 RQD Modeling and Lithology <br /> As discussed in Chapter 4, CNI uses a combination of laboratory testing and the degree <br /> of in situ fracturing(RQD) to determine rock-mass strength. The RQD distribution for each <br /> cross section was estimated from the 2011 RQD block model generated and provided by CC&V. <br /> RQD estimations for the SLOPE/W runs were generated in Mine Sight from three-dimensional <br /> solids extruded 200 feet perpendicular to the sections in both directions. The distribution of <br /> RQD in each section is presented in Figure 7-5. The 70%reliability values of the RQD <br /> distributions were used for the analysis (i.e. 70%of measured RQD block values are greater <br /> than value used).The 10 cross sections, along with the 2011 MLE2 mine area shells, RQD block <br /> model, and drill-hole intercepts, can be seen on the even numbered Figures between 7-6 and 7- <br /> 25. The critical failure surfaces are shown underlain by the lithology on the odd numbered <br /> Figures between 7-6 and 7-25. <br /> 7.2.5 2011 Geotechnical Drilling <br /> One of the goals of the 2011 drilling program was to expand the RQD block model to the <br /> WHEX and Globe Hill areas, where very little RQD data existed. Drilling of these holes <br /> was completed concurrently with the publication of this report. The data from these holes was <br /> utilized for the analysis; however, the RQD block model was not updated at the time this report <br /> was published. <br /> 7.3 Overall Stability Analysis Results <br /> Results of the overall stability analysis runs are summarized in Table 7-2. CNI typically <br /> considers a FOS above 1.20 appropriate for final wall mine slopes. From the standpoint of <br /> 26 <br />