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6.2.1 East Wall <br />Historically, the east wall has had no major instability issues. The stereonet plot <br />for the east wall was derived from the full dataset (Figure 10) shows multiple <br />plunges of lines of intersection less than the angle of the slope face, resulting in <br />the interpretation that the potential for sliding exists along these intersections. <br />However, all of the wedges indicate that sliding will not occur unless friction <br />angles are less than 33°, therefore showing that they are stable for the existing <br />45° slope angle. <br />Foliation plane F-3 intersects joint P-5 within the daylighting envelope and <br />therefore, if this foliation is located in the eastern wall area sliding could occur. <br />The stereonet plot also shows that F-1, F-2 and F-3 intersect, resulting in a <br />plunge of line of intersection less than the angle of the slope face and thus <br />indicating the potential for sliding, although it is questionable at this time if the <br />foliations would occur in the same place to allow for this relationship to occur. <br />The emergence of F-2 and F-3 as definitive discontinuity sets have been <br />identified only over the past three years as a result of the 2003 geotechnical <br />investigation, the 2004-2005 field mapping efforts, and the current 2006 mapping <br />effort. To date, not enough data have been collected to define the extent of the <br />F-2 or F-3 discontinuity sets or to delineate if all of the foliation discontinuities <br />occur in the same location simultaneously. Or if localized faulting within the <br />quarry has resulted in °structural blocks", or regions where the dominant foliation <br />sets occur separately, although more data are required to fully support this <br />hypothesis. Until further data are collected, the intersection of the foliation <br />planes (F-1, F-2 and F-3) will not be evaluated in the wedge stability analyses <br />presented herein. <br />For the nearly vertical bench face (prior to reclamation), additional potential <br />wedges may exist due to the steep overall slope angle. These wedge failures <br />have been observed occasionally on the east wall and are localized in extent. <br />~s- <br />