2009-09-14_REVISION - C1981019 - Laserfiche WebLink

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spoil ridges remain ungraded in the pit. The Division recalculated the reclamation cost estimate to ensure adequate bond monies are available to complete the reclamation in the event of permit revocation and bond forfeiture. C. Approximate Original Contour Information on achieving approximate original contour (AOC) is presented in Sections 2.05.3, 2.05.4, 4.14.1 and 4.14.2 of the Permit (Volume 1 for the East Pit, West Pit, Section 16 Pit, Facilities Area and Gossard Loadout and Volume 12 for the South Taylor Pit). Maps 18, 18A, 19, 19A and 19B show the pre- and post-mining topography, respectively. Maps 33, 33A and 33B show the post-mining drainage profiles. Maps 24 and 24A contain mining range diagrams, and Maps 29 and 29A show the sequence of spoil grading. in general, Coiowyo will return all mined lands in the East Pit, West Pit and Section 16 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 (and will) resulted in these materials expanding in volume approximately 20 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 one temporary, excess spoil fills were authorized to accommodate such expansion of overburden for the East Pit, West Pit and Section 16 Pit. 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 Permit. 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 Permit. 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 and 33A. 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 (1 v:3h). Stock tanks of less than two acre-foot in storage capacity and embankments of less than five foot may be built and retained (following Division approval) to provide for the approved post-mining land use. 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 Proposed Decision and Findings of Compliance 14 September 2009 Permit Renewal 05 Page 55