2010-12-17_REVISION - C1981019 (108)

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RULE 2 PERMITS 2.05.4 (2)(c) Backfilling Plan 1W As mining progresses to the south, overburden material from each successive cut will be backfilled into the previously mined out area and the additional spoil will continue to buildup in previously mined areas. Initially a temporary out of pit spoil pile will be created to the North of the Collom Lite Pit and will remain in place until the end of mine life. Table 2.05.6 -5 presents a mine wide volumetric calculation in support of post mining topography and illustrates that permanent out of pit spoil will not be needed. The backfilled mining areas will be graded to establish a stable post mine topography that blends into the undisturbed areas outside the mining limits (Map 19C). Colowyo will grade all final slopes so that overall grades do not exceed 3H:1 V (Map 20C). Where necessary, the spoil surface will be roughened by ripping or discing etc., to ensure a bond between the topsoil and spoil to reduce slippage. To date there is no evidence of topsoil slippage on reclaimed areas in the existing permit area. A few small tension cracks resulting from settling of fill and topsoil have occurred in a few areas within a year or two after reclamation, but soon stabilize and begin to fill in. The final surface as shown on the Post - mining Topography Map (Map 19C) will approximate the overall pre- mining grades (Map 19D). Appropriate cross sections that show the anticipated final surface configuration of the proposed permit area, in conjunction with the existing pre- mining topography, are shown on the Pre - mining and Post - mining Cross Section (Map 20C). The regrading plan reestablishes escape cover, south facing slopes for wintering big game populations and small drainages suitable as future location of stockponds necessary to achieve the post- mining land use. 2.05.4 (2)(d) Topsoil Salvage Topsoil Redistribution Plan Prior to any mining - related disturbances in the Collom area, all available topsoil will be removed from the site to be disturbed as discussed in Section 2.05.3, and will be redistributed or stockpiled as necessary to satisfy the needs of the reclamation timetable as described herein. Final grading before topsoil placement will be conducted in a manner that minimizes erosion and provides a surface for the topsoil that minimizes slippage. If spoil compaction is a problem, the spoil will be ripped with a dozer to minimize compaction, assure stability and minimize slippage after topsoil replacement. Where possible, development of concave landforms (to encourage snow entrapment) will be developed on a case -by -case basis at the discretion of the field supervisor. Such landforms will still have positive drainage in accordance with overall permitted designs. Topsoil will then be redistributed and graded to a variable replacement depth following the general rule of thin topsoil ( <6) inches on ridge tops to gradually thicker topsoil moving down the slopes to the drainage bottoms for the grazingland land use targeted areas (see representation below). Sagebrush Steppe areas will ideally receive an average of approximately 4 inches of topsoil that will likely be a more uniform application to encourage proper seeding depth and overall shrub establishment conditions (see representation below). Colowyo will track the volume of topsoil applied to each reclamation unit and report it within the Annual Reclamation Report each year. Colowyo utilizes load counts and time card coding to differentiate and accurately assign costs /volumes for all other material movement on the mine site. As such, Colowyo will utilize these tools to ensure the planned and appropriate volume of topsoil is applied to each reclamation unit in the Collom Area. A visual representation of Colowyo's Collom area drainage -wide topsoil replacement strategy is provided below: Collom —Rule 2, Page 101 Revision Date: 1/23/09 Revision No.: PR -03