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daylight in the slope face and therefore these two pairs (P4:P6 and P5:P2) should <br />continue to be monitored as the excavation continues. <br />The wedge stability analysis for the southeast wall indicates five pairs of intersecting <br />planes that have plunge lines inclined shallower than the slope face, with only one of <br />these (P4:P6) is inclined steeper than the friction angle. The intersection of the planes for <br />discontinuity sets P-4 and P-6 is inclined parallel to the slope face and so potentially <br />unstable wedges are likely to be surficial in nature. For the current analysis, two pairs of <br />planes are found to fall within the failure envelope (F3:P6 and P3:P6) and therefore, <br />failure is possible along these planes. <br />As mentioned previously for the east wall, the individual benches along the south walls <br />with near vertical faces enable additional discontinuities to form potential wedges that may <br />slide during the temporary conditions prior to reclamation. Wedge failures limited to <br />individual benches have been consistently observed in the past along the south walls. <br />The recently identified discontinuity set, F-3, appears to dominantly influence the potential <br />for failures along the southwest walls that could be either wedge blocks (F3:P6 whose <br />plunge line is inclined just less than the failure envelope) of planar blocks (e.g. F3:P2:P1 <br />or F3:P6:P1, etc.). <br />In previous annual reports, toppling about discontinuity plane P-1 also existed as another <br />mechanism of potential block movement for the southeast wall. However, as shown on <br />Figure 16 both the slope face and discontinuity plane P-1 no longer share the same basic <br />strike. A review of photographs during previous annual studies does indicate that there <br />are some continuous surfaces that form the face of the south wall. However, none of <br />these surfaces appear to be identified as plane P-1, which has an average dip of 76° to <br />the south. <br />The foliation F-1 also strikes in the same general direction as both the southeast slope <br />face and discontinuity plane P-1, although at an overall shallower dip. It is believed that <br />-18- <br />Lachel & Associates <br />A 5C14NABF1 FNGIN[FRING, O) PANY