1988-04-11_PERMIT FILE - C1981008A (23)

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Peabody will apply for a modification of the existing NPDES permit (CO-0000213) to include the proposed 007 pond to be constructed in the Nucla East mining area. All terms and agreements specified in the approved permit will be adhered to during the mining operation to ensure that effluent will meet the permit limitations. Based on past water quality monitoring, it is anticipated that no treatment of pond effluent is necessary. However, should the need for treatment of pond effluent be demonstrated, Peabody will commit to designing treatment facilities or procedures to handle the equivalent of a 10-year, 24-hour effluent volume. Plans for sampling overburden and topsoil after backfilling and grading have been completed, to identify potentially deleterious materials, have been developed and are presented in Tab 21 (Minesoil Reconstruction). Based on these plans, surface runoff from disturbed reclaimed areas will not come in contact with materials that would contribute to elevated levels of acid or toxic constituents. Topsoiling handling procedures (Tab 21, Minesoil Reconstruction) and revegetation methods (Tab 22, Revegetation Plan) have been developed to stabilize the landscape, prevent erosion, and minimize the additional contributions of sediment to runoff. They include: the seeding of temporary disturbance and topsoil piles; mulching, chisel plowing and deep ripping; cover cropping; and timely reseeding of reclaimed areas (regraded and topsoiled) with seed mixes designed for rapid establishment and development of effective hydrologic cover. Those areas that are affected by mining will be graded to postmining topographies that generally feature slopes no greater than 5:1. In combination with the reclamation and topsoil handling techniques, reduced slopes will minimize the potential for erosion due to accelerated sheet wash or gullying. The reestablished reclaimed channel (West Return Ditch) was constructed to have a postmining gradient similar to premining conditions. Revegetation methods and seed mixes used to reclaim the reestablished reach of this affected channel have resulted in stable conditions as reflected by TSS monitoring performed at Site SW-N6 since 1980. The Surface Water Control Plans (Exhibits 13-4 and 13-5, Tab 13, Facilities) developed for both mining areas, include five temporary diversions. All diversions have been designed according to accepted design criteria, and will be built to minimize erosion and prevent 16-5 Revised 04/11/88