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~J ~'~ 1 these surfaces is unlikely. For the set that is within the failure envelope (i.e. P-1 and P-6) sliding is assumed to occur as the plunge of the line of intersection exceeds the 33° angle of friction. The second western wall analyzed in this study, has a dip direction of 120° (Figure 15). The results for this analysis yielded fairly comparable results, with two intersecting planes falling outside the failure envelope and one set mapped within. The intersection of discontinuities F-1 and P-2 fall just within the shaded region and sliding is assumed to occur as the plunge of the line of intersection exceeds the 33° angle of friction. 6.2.4 South Walls As with the north wall and west wall, the southern wall has also been subdivided into separate slopes for analysis: two southwest walls and a southeast wall orientation were selected based on the proposed Lafarge mine plan (Lafarge, 2003}. This approach is the same as was used for the 2004 annual report, in which the southern walls were measured based on configurations on the proposed Lafarge mine plan (Lafarge, 2003). Figures 16 and 17 present the stereonets for each wall. Similar to the results of the 2004 investigation, the intersection of the planes for discontinuity sets P-2 and P-4 lies just outside the 33° friction angle for all three southern wall orientations, and therefore are not indicative of conditions conducive to sliding along the intersection. The wedge stability analysis for the southeast wall indicates one plunge of a line of intersection that is just outside of the failure envelope. The intersection of the planes for discontinuity sets P-3 and P-6 are therefore not anticipated to fail unless the friction angle along the planes is lower than the average. This condition has been noted in past reports, and the south walls should be continued to be monitored as excavations continue. -2~-