2009-02-17_REPORT - M1974004 (2)

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events, and based on continued photo documentation and visual monitoring since that time, no additional movement has been detected (Photo 8). Based on the latest topographic map of the quarry provided to us (December, 2007), the overall effective angle of the north pit walls has been modified over the last three benches to an angle of 35° per LF&A recommendations in the May 2003 report. The failure surfaces (i.e. the surfaces along which movement has occurred) remain at a "residual strength" and therefore are less resistant to additional loading. Although the slope configuration is currently stable, the failure mechanism could potentially be reactivated upon removal of subsequent benches, resulting in movement of additional material. 9) The highwall adjacent to the lower asphalt plant facilities and the area above the ' highwall were visually inspected as part of the field reconnaissance inspections performed in January 2009. As discussed in Section 2.0, the bedrock in the highwall of the asphalt plant is sedimentary, consisting of shales and sandstones upturned to near vertical orientations, striking almost north-south. The highwall located immediately west and north of the plant facility is currently stable, with no evidence of highwall instabilities. No major cracks, settlement, or water ponding ' areas were observed at the ground surface above the highwall, and it appears that the highwall is stable under the current conditions. In addition to the inspection of the highwall, observations along the access road to the upper asphalt plant facilities were also made with no surface cracks or settlement noted. The road is aligned perpendicular to the strike of the nearly ' vertical bedded sedimentary rock, which is a favorable orientation for slope stability along the access road. ' -10-