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<br /> wall, as it is limited to less than a single bench in height, and is considered <br /> a localized wedge failure. <br /> <br /> 10) A section of the northeast wall of the main pit originally experienced planar <br />' failure along the foliation planes in 1998. Following removal of the next <br /> bench in 1999, a larger section that is approximately 350 feet wide by 250 <br />' feet high, experienced planar failure. The north wall pit slopes were <br /> modified in response to these failures, and based on continued photo <br />' documentation and visual monitoring since that time, no additional <br /> movement has been detected (Photo 10). As described in previous annual <br />' f <br />il <br />i <br />h <br />d <br />h <br />rt <br />th <br />li <br />d t <br />ti <br />f <br />li <br />ti <br />b <br /> repo <br />ave occurre <br />w <br />s, <br />ure <br />e <br />eve <br />o <br />en a con <br />nuous <br />e <br />a <br />s <br />o <br />a <br />on <br />' plane was intersected by two or more existing discontinuities, and <br />h <br />l <br />S <br /> tabi <br />daylighted in the exposed highwall. (See t <br />e Wedge <br />ity Analysis <br />' section of this report for a complete description of this type of failure). <br />' Based on the current topographic map (December, 2003) of the quarry, the <br /> overall effective angle of the north pit walls has been modified over the last <br />' three benches to an angle of 35° per LF&A recommendations in the May <br /> 2003 report. The failure surfaces (i.e. the surfaces along which movement <br /> has occurred) remain at a "residual strength" and therefore are less <br /> resistant to additional loading. Although the slope configuration is currently <br /> stable, the failure mechanism could potentially be reactivated upon removal <br /> of subsequent benches, resulting in movement of additional material. <br />11) The highwall adjacent to the lower asphalt plant facilities and the area <br />above the highwall were visually inspected as part of the field <br />reconaissance inspections performed on March 19, 2005. Unlike the <br />highwalls for the areas currently being mined, the bedrock in the highwall of <br />the asphalt plant is sedimentary, consisting of shales and sandstones <br />upturned to near vertical orientations, striking almost north-south. <br /> <br />-13- <br />