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t <br />which the southern walls were measured based on configurations on the <br />proposed Lafarge mine plan. Figures 14 and 15 present the stereonets for each <br />wall. <br />Similar to the results of the 2004 investigation, the intersection of the planes for <br />discontinuity sets P-2 and P-4 lies just outside the 33° friction angle for all three <br />southern wall orientations, and therefore are not indicative of conditions <br />conducive to sliding along the intersection. <br />The wedge stability analysis for the southeast wall indicates one plunge of a line <br />of intersection that is just outside of the failure envelope. The intersection of the <br />planes for discontinuity sets P-3 and P-6 are therefore not anticipated to slide <br />unless the friction angle along the planes is lower than the average. This <br />condition has been noted in past reports, and the south walls should be <br />continued to be monitored as excavations continue. <br />As mentioned previously for the east wall, the individual benches along the south <br />walls with near vertical faces enable additional discontinuities to form potential <br />wedges that may slide during the temporary condition prior to reclamation. <br />Wedge failures limited to individual benches have been consistently observed in <br />the past along the south walls. <br />The newly identified discontinuity set, F-3, may facilitate some failures along the <br />south walls that would involve the formation of a wedge with discontinuities P-3 <br />and P-6 very close to the failure envelope. <br />The average orientation of the F-3 data collected for the 2005 report is <br />approximately parallel with the southeast wall, with an average dip that is only a <br />few degrees shallower than the southeast wall (45°), but the average orientation <br />of the 2006 data is somewhat oblique to the wall. <br />-22-