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<br />orientations for stability. Two west wall orientations were analyzed in this study. The <br />first had a dip direction of 091 °, and using this orientation the stereonet plot (Figure 14) <br />shows one pair of planes having a line of intersection that plunges less than the angle of <br />the slope face and steeper than the failure envelope (P6:P1). Three lines of intersection <br />have plunge angles less than the angle of the lope and lower than the critical friction <br />angle, indicate that sliding along these surfaces is possible but unlikely. The plunge line <br />for the intersection of plane P-6 with the steeper dip for F-1 analyzed is just within the <br />failure envelope, and so, if the foliation dips at 46° in this area, a potential for sliding <br />does exist and should be monitored. <br />The second western wall analyzed in this study, has a dip direction of 120° (Figure 14). <br />The results for this analysis yielded fairly comparable results. There are seven pairs of <br />intersecting plans with plunge lines that daylight the slope face, but only two whose <br />plunge lines are steeper than the angle of friction. The plunge of the intersection of <br />discontinuities P-1 and P-2 is just less than the inclination of the slope, and exceeds the <br />33° angle of friction. Additionally, P-2 and F-1 were found to intersect within the failure <br />envelope at both the typical F-1 dip and the steeper variation. This is the first time this <br />combination of planes was found to have potential for failure, and should be continued <br />to be monitored and evaluated in future studies. <br />5.2.4 South Walls <br />As with the north wall and west wall, the southern wall has also been subdivided into <br />separate slopes for analysis: two southwest walls and a southeast wall orientation were <br />selected based on the proposed Lafarge mine plan (Lafarge, 2003). This approach is <br />the same as was used for previous annual reports, in which the southern walls were <br />measured based on configurations on the proposed Lafarge mine plan. Figures 15 and <br />16 present the stereonets for each wall. <br />In the southwest wall, the stereonet shows four pairs of intersecting planes that have <br />plunge lines inclined shallower than the inclination of the slope face, but all are inclined <br />less than the friction angle. Consequently, all pairs of planes are capable of forming <br />wedge blocks, but none of these wedges are likely to be unstable. The stereonet also <br />-17-