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dip angles for F-1 correspond to one standard deviation above and below the <br />mean dip angle of 36° (i.e., 46° and 26°). <br />6.2.1 East Wall <br />Historically, the east wall has had no major instability issues. The stereonet plot <br />for the east wall (Figure 10) was derived from the full dataset and 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 indicating 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 occur with enough frequency to allow for this relationship to occur <br />locally. <br />The emergence of F-2 and F-3 as definitive discontinuity sets have been <br />' identified only over the past few years as a result of the 2003 geotechnical <br />' investigation, the 2004-2006 field mapping efforts, and the current 2007 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. Another possibility is that localized <br />faulting within the quarry has resulted in "structural blocks", or regions where the <br />dominant foliation sets occur separately, although more data are required to fully <br />' support this hypothesis. Until further data are collected, the intersection of the <br />foliation planes (F-1, F-2 and F-3) will not be evaluated in the wedge stability <br />analyses presented herein. <br />' -19- <br />