2018-07-09_GENERAL DOCUMENTS - C1981019

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Proposed Decision and Findings of Compliance July 2018 Permit Renewal No. 7 P a g e | 46 2.05.4, 4.14.1 and 4.14.2 of the PAP. Maps 18, 18A, 18B, 19, 19A, 19B and 19C of the PAP show the pre- and post-mining topography. Maps 33, 33A, 33B and 33C of the PAP show the post-mining drainage profiles. Maps 24 and 24A of the PAP contain mining range diagrams, and Maps 29, 29A and 29B of the PAP show the sequence of spoil grading. In general, Colowyo will return all mined lands in the East Pit, West Pit and Collom Pit to approximate original contour, with reclaimed surfaces resembling the general surface configuration of the area (though changes will occur on a smaller scale). However, the removal and redistribution of overburden has resulted (and will result) in these materials expanding in volume approximately 15 percent. This will result in the overall topography being approximately five feet higher than was the case in the original landscape. Post-mining topography at even higher grades has been approved for areas of excess spoil fills. Three permanent and two temporary excess spoil fills were authorized to accommodate such expansion of overburden for the East, West, Section 16 and Collom Pits. The three permanent excess spoil fills are valley fills and have thus changed the topography of those areas. Information on the temporary spoil pile (for final Section 16 and West Pit closures) can be found in Section 4.14.1 of the PAP. Information on the three permanent fills can be found in Sections 2.05.3 and 4.14.1; Maps 18, 19, 30, 33 and 33A; and Exhibits 12 and 19 of the PAP. A summary of this information can be found in this document in Section B, Item VII. Drainages 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 Maps 33, 33A, 33B, and 33C of the PAP. Final grading plans provide a surface that minimizes erosion and slippage following the placement of topsoil. Final slopes, in general, do not exceed one vertical to three horizontal (1v:3h). Beginning in 1983, surveys were conducted to assure attainment of approximate original contour. Survey results were submitted on a yearly basis as part of Colowyo's Annual Reclamation Report. In 1987, this requirement was reduced to require survey reports only every two and one-half years. In 1992, swell factor monitoring and analyses were terminated (PAP Volume I, Section 4.14.2). In the South Taylor Pit, with the exception of the two valley fills, Colowyo will return all mined lands to approximate original contour, with reclaimed surfaces resembling the general surface 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 Land Management Company 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.