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<br /> <br /> <br /> <br />PR-04, Colowyo Coal Mine C1981-019 52 August 2016 <br /> <br />complement the drainage pattern of the surrounding terrain. Final grading plans provide a <br />surface that both minimizes erosion and slippage following the placement of topsoil. Final <br />slopes, in general, do not exceed one vertical to three horizontal (1v:3h). <br /> <br /> <br />Information on achieving AOC is presented in Sections 2.05.3, 2.05.4, and 4.14 of the PAP. <br />Maps 18B and 19C show the pre- and post-mining topography, respectively. Map 20C shows <br />the pre- and post-mining cross sections. Map 33C shows the pre- and post-mining drainage <br />profiles. Map 29B shows the sequence of spoil grading. <br /> <br /> <br />D. Specific Findings Required by Section 4.14 <br /> <br />These specific findings are applicable to all areas of the Colowyo Mine including the East Pit, <br />West Pit, Section 16 Pit, the South Taylor Pit, and the Collom permit expansion area, including <br />the Collom Pit. <br /> <br />1. The Division approved the retention of box cut spoil or initial cut spoil outside the pit <br />area since CCC has demonstrated that such material is not required to achieve AOC in <br />accordance with Rule 4.09.1 [Rule 4.14.1(2)(d)]. <br /> <br />2. CCC demonstrated that fill proposed to eliminate the highwall and depressions meets <br />all the requirements of 4.05, 4.06, 4.09 and 4.15. Therefore, the Division proposes that <br />excess material not required for reclaiming highwalls and other depressions need not be <br />returned to AOC [Rule 4.14.1(2)(a)]. <br /> <br />3. In order to conserve soil moisture, ensure stability, and control erosion on final graded <br />slopes, the Division approved cut-and-fill terraces. These terraces are compatible with the <br />postmining land use, and will meet all the requirements of Rule 4.14.2(2). <br /> <br />4. Permitted small depressions (less than two acre-foot of capacity, embankments less <br />than five feet in height) in the backfill are used to minimize erosion, create or enhance <br />wildlife habitat, conserve soil moisture, and promote revegetation. The Division <br />specifically approves each such small depression [Rule 4.14.2(3)]. <br /> <br />5. The Division approved CCC's plan for disposal of debris, acid-forming or toxic <br />materials, or materials constituting a fire hazard in a manner designed to prevent <br />contamination of ground or surface waters. A contingency plan has also been developed <br />to prevent sustained combustion of flammable materials [Rule 4.14.3(1)(a)]. <br /> <br />6. The Division approved the method and design specifications for covering of acid-and