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Januari, 15, 2008 <br />6.0 SUMMARY <br />Page 60 <br />This report has documented characterization efforts for the G-Pit landslide and <br />surrounding mining areas. The laboratory testing and borehole characterization program have <br />been described and results have been summarized as they impact future mining. Results tirom <br />previous stability analyses were summarized and new analyses of the spoil stability have been <br />presented. Our understanding of mechanisms leading to the landslide and expected current <br />conditions, as applicable to mining this area, are discussed. Recommendations for cut slope <br />angles and spoil pile angles are provided and comments on the mining plan are given from a <br />geotechnical perspective. The results of this work are summarized as follows. <br />• The slide plane of the landslide is approximately 96 ft below ground in the weak L-Roof <br />mudstone layer. The slide plane undulates with bedding and sheared through high points <br />in the beds disturbing the L-Seam reserves. <br />• The rock mass within landslide block is disturbed to various degrees. The most <br />disturbance is updip in the tensile failure region and along the perimeter where shearing <br />occurred over the large movement. <br />• This disturbance will manifest during mining as loose blocks. Flatter cut-face slopes will <br />be required in unfavorable areas to ensure local stability. <br />• The ground below the landslide is essentially undisturbed. The exception is near the old <br />G-Strike Pit area where disturbance on the weak Q-Floor mudstone was observed. <br />• The post-landslide ruck mass strengths are lower than pre-landslide due to open fractures <br />and loss of confinement. Rock mass strengths below the slide plane are similar to pre- <br />landslide estimates. <br />• Estimates of recoverable reserves are provided in Table 4. There is a high likelihood of <br />recovering most reserves in the L-Seam and below. <br />• Stability ofthe spoils on the weak Q-Floor mudstone bedding is dependent on the local <br />bedding dip. It is recommended that the spoil pile height not exceed 68 ft in areas where <br />the average bedding dip 13°. Steeply dipping areas of' K-Pit will require a reduction in <br />the maximum spoil pile height to 30 ft and the outer slope face of the pile must be <br />sufficiently compacted to maintain stability and prevent creep failure (see Section 4.4). <br />• It is expected that the ground below the landslide can he mined using conventional dip-pit <br />dragline methods. In the landslide, a truck and shovel mining method is recommended <br />due to the disturbed ground. <br />• Piling spoils as high as practical in the old G-Strike Pit area will help to stabilize the <br />landslide prior to mining. <br />• The risk of similar landslide events occurring in other areas of the mine, especially in <br />Z-Dip Pit area and F.ast-Panel area are low given the current knowledge ofconditions. <br />• Dewatering wells should be pumped to remove groundwater from landslide and spoil <br />piles. This will significantly improve stability. <br />• Monitoring should be continued throughout mining ofthe K-Pit and G-Pit area and data <br />should be analyzed. Sudden changes will require additional monitoring or immediate <br />operational action. Monitoring should include: regular visual cut-face inspection, large- <br />Agapito Associates, Inc.