2010-05-12_PERMIT FILE - C1981010

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February 1, 2010 Page 8 • The slope gradient should be reduced by excavating material rather than adding material by dozer grading the slope. • These areas of concern should be addressed prior to working within 500 ft down slope of the area. • Baulroads should be designed with maximum cut and fill slopes of 3.H:1 V when located in or above the [-Seam. K -Pit Buttress • The most recent modeling indicates that the K -.Pit buttress is not necessary for the stability of the reclaimed K -Pit, nor will it enhance the stability of mining the K -Pit. Therefore, no buttress is required. • The timing of fill placement and reclamation of the AE -.Pit can be adjusted to minimize haul distances. • The subgrade materials in reclaimed G- Strike pit and A.E -Pit are not conducive to large (tall) spoil piles; therefore, AAI recommends that spoils placed in the AE -Pit location be limited to a single 50 -ft- thick lift (50' above existing ground). • The spoils can be placed over the entire reclaimed AE -Pit if necessary. • The pre -fill topography should allow for positive drainage away from the fill location for all. phases of the construction. • A. suitable berm must be constructed at dump points, allowing end dump trucks to back up to the edge of the fill, and dump. • Following the final grading of the fill, topsoil should be brought back to cover the area, which will be permanently vegetated, in accordance with the permit accorded to TMI. • While the spoil placement and grading in the AE -Pit area is not subject to mandatory regulatory inspection, AAI recommends TMI to inspect the placement of fill on a regular basis and report any signs of instability to AAI. • Any conditions noted that would warrant modifications to the design should be documented and analyzed in a timely fashion. 5.0 REFERENCES Agapito Associates, Inc. (2009a), "Geotechnical Assessment of the K -Pit Mine Plan -- Trapper Mine, Colorado," prepared for Trapper Mining, Inc., April. Agapito Associates, Inc. (2009b), "K -Pit Buttress Fill Stability Analysis— Trapper Mine, Colorado," prepared for Trapper Mining, Inc., May. Agapito Associates, Inc. (2008a), "Simplified K -.Pit with Toe Buttress Stability Analysis Report" prepared for Trapper Mining, Inc., July. Agapito Associates, Inc.