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Mr. Jim Mattem <br />March 19, 2007 <br />Page 49 <br />• Gd-2 Dip box cut provided the required degree-of-freedom for large-scale kinematic <br />block movement to the north-northeast direction. <br />• Prior to Gd-2 mining, global slope failure was not indicated. <br />• The ground is inherently less stable on the south and west sides of G-Pit due to the <br />increased bedding dip. The updip tensile blocks only move after the main landslide block <br />is released because the main landslide block provides sliding resistance until it releases <br />under elevated groundwater and reduced strength conditions. <br />• Only limited lab data is available on the weak mudstone seam, in part because the seam is <br />quite thin. <br />• Failure mechanism on the west side of landslide is complex and includes slip on the <br />mudstone seam, steep dip of beds updip of the main block, tensile opening of sandstone <br />fractures above the mudstone, and high water pressures resulting in low effective stresses. <br />• Failure limits predicted by the model agree reasonably well with mapped surface <br />cracking. <br />• The power pole location does not indicate eminent global active tensile failure. <br />• Given the assumptions necessary to induce failure, it is concluded that global failure <br />could not have predicted ahead of event. <br />I hope we have addressed your request related to providing our observations from our site <br />visit of October 11, 2006, related to the G-Pit landslide event. Should you have questions, please <br />contact me to discuss this letter report at your convenience. As always, we appreciate the <br />opportunity to assist Trapper Mining, Inc., in addressing their geotechnical engineering issues. <br />Yours sincerely, <br />John P. Tinucci, PhD, PE <br />Sr. Associate <br />JT/smvf <br />Agapito Associates, Inc. <br />