2018-08-06_GENERAL DOCUMENTS - C1981019

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configuration of the area (though changes will occur on a smaller scale). The Division has, however, granted a variance from AOC for the steep slopes at the edges of the South Taylor Pit. These steep -slopes will be graded to a more gently -sloping topography, which will enhance the post -mining land uses of rangeland and wildlife habitat. These lands are owned by the Colowyo Coal Company L.P. and the BLM. Both Colowyo and the BLM have provided letters approving of the post -mining topography and the change in AOC, located in figure 2.064-1 of the PAP. Maps 18A and 19B of the PAP show the pre -mining topography and post -mining topography of the South Taylor Pit, respectively. Drainages in the South Taylor Pit are constructed with gradients similar to those originally present, and complement the drainage pattern of the surrounding terrain. Pre -mining and post -mining drainage profiles are found on Map 33B of the PAP. Final grading plans for the South Taylor Pit provide a surface that both minimizes erosion and slippage following the placement of topsoil. Final slopes, in general, do not exceed one vertical to three horizontal (lv:3h). The Collom area to be mined will be restored to a topography approximating pre -mining grades. The slopes of backfilled areas, as necessary, will utilize contour furrows for erosion control and stability. Final grading plans for the Collom pit will be conducted in a manner that minimizes erosion and provides a surface for topsoil that minimizes slippage. Final grading will be accomplished that overall grades will not exceed lv:3h. Backfill and grading for the Collom Pit is shown on Maps 19C and 29B of the PAP. D. Specific Findings Required by Section 4.14 The following specific findings are applicable to all areas of the Mine including the East Pit, West Pit, Section 16 Pit, South Taylor Pit and Collom Pit. 1. The Division approved the retention of box cut spoil or initial cut spoil outside the pit area since Colowyo has demonstrated that such material is not required to achieve approximate original contour in accordance with Rule 4.09.1 (Rule 4.14.1(2)(d)). 2. Colowyo demonstrated that fill proposed to eliminate the highwall and depressions meets all the requirements of 4.05, 4.06, 4.09 and 4.15. Therefore, the Division proposes that excess material not required for reclaiming highwalls and other depressions need not be returned to approximate original contour (Rule 4.14.1(2)(a)). 3. In order to conserve soil moisture, ensure stability, and control erosion on final graded slopes, the Division approved cut -and -fill terraces. These terraces are compatible with the post -mining land use, and will meet all the requirements of Rule 4.14.2(2). 4. Permitted small depressions (less than two acre-foot in capacity, embankments less than five - feet) in the backfill are used to minimize erosion, create or enhance wildlife habitat, conserve soil Revised Proposed Decision and Findings of Compliance August 2018 Permit Renewal No. 7 P a g e 147