2009-09-21_PERMIT FILE - C1981010A (46)

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• The area to be filled will be property prepared and constructed, in accordance with Agapito Associates, Inc.'s "K-Pit Buttress Fill Stability Analysis" from May 2009. A copy of this geotechnical investigation document is included in Appendix T. The buttress will be constructed in lifts from the existing topography. Lifts will not exceed 100 vertical feet, and will typically be 25 to 50 vertical feet In general, these lifts will be placed from the outside toward the center by a Truck/Excavator fleet A suitable berm will be constructed at dump points, allowing end dumps to back to the edge of the fill. As conditions require, and more likely with increased lift height, trucks may dump short of the berm, and use of a dozer to push the material to the lift edge will be required. The slopes of the fill are planned at 3H:1V. It will be contoured to blend with existing topography. Lifts will be constructed to promote drainage and reduce the ability of water to stand on the surface. This will minimize the amount of infiltration into the fill. The buttress is an excess spoil fill, and will be left as a permanent feature. This will enhance the long term stability of the area. As such, the fill will be retopsoiled, and planted in permanent vegetation, in accordance with TMI's permit This is consistent with the planned post mining land use of Rangeland and • Wildlife Habitat Inspection of Fills Horse Gulch Fill and the Buttress Fill will be inspected for stability by a registered engineer or other qualified professional specialist experienced in the construction of earth and rockfill embankments under the direction of a qualified professional engineer at least quarterly throughout the construction and during the removal of all organic material and topsoil, placement of the underdrainage system where applicable, installation of surface drainage systems, placement and compaction of fill materials and revegatation. The qualified engineer will provide the Division a certified report within 2 weeks after each inspection that the fill has been constructed as specified in the design approved by the Division. The report will include a description of any appearances of instability, structural weakness and other hazardous conditions observed during the inspection. A copy of the report will be maintained at the mine site. Certified reports addressing the underdrain system and protective fitters will include color photographs taken during and after construction, but before underdrains are covered with excess spoil. If the underdrain system is constructed in phases, each phase will be certified separately. Where excess durable rock spoil is placed in single or multiple lifts such that the underdrain system is constructed • simultaneously with excess spoil placement by natural segregation of dumped materials, photographs will \ 3-40b Revision: PR-- loo a.F,proved: