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The discussion for surface water protection has been separated into three parts: 1) surface water <br />quality; 2) surface water quantity; and 3) surface water monitoring. <br />Surface Water Quality Sediment ponds will be adequately designed and will be constructed <br />during the proposed operations for controlling surface water runoff from disturbed and reclaimed <br />areas. An NPDES permit will be obtained from Water Quality Control Division, Colorado <br />Department of Public Health and Environment to allow the discharge of water from the sediment <br />ponds. The design of the ponds has been developed to prevent additional contributions of <br />sediment to stream flow outside the permit area, to minimize erosion, and incorporates detention <br />times sufficient to ensure that all applicable effluent standards will be met. The pond discharge <br />structures are designed according to standard engineering design procedures for protecting <br />against erosion via emplacement of riprap and /or energy dissipaters. The pond will be removed <br />and reclaimed following the completion of mining and reclamation unless prior approval to <br />retain this impoundment is obtained. <br />The impact of a sediment pond and runoff from reclaimed areas on the quality of receiving <br />streams was found to be of minimal significance (see Probable Hydrologic Consequences at the <br />end of this section). All terms and agreements specified in the approved NPDES permit will be <br />adhered to during the mining operation to ensure that effluent will meet the permit limitations. <br />Based on past water quality monitoring at New Horizon 2 Mine, it is anticipated that no <br />treatment of pond effluent is necessary. However, should the need for treatment of pond effluent <br />be demonstrated, WFC will commit to designing treatment facilities or procedures to handle the <br />equivalent of a 10 -year, 24 -hour effluent volume. <br />Plans for sampling overburden and topsoil after backfilling and grading have been developed and <br />are presented in Section 2.05.4(2)(d), Topsoil Redistribution. Based on these plans, surface <br />runoff from disturbed reclaimed areas will not come in contact with materials that would <br />contribute to elevated levels of acid or toxic constituents. <br />Topsoil handling procedures (Section 2.05.4(2)(d), Topsoil Redistribution) and revegetation <br />methods (Section 2.05.4(2)(e), Revegetation) have been developed to stabilize the landscape, <br />prevent erosion, and minimize the additional contributions of sediment to runoff. They include: <br />the seeding of temporary disturbance and topsoil piles; mulching, chisel plowing and deep <br />ripping; cover cropping; and timely reseeding of reclaimed areas (regraded and topsoiled) with <br />seed mixes designed for rapid establishment and development of effective hydrologic cover. <br />Those areas that are affected by mining will be graded to post mining topographies that generally <br />feature slopes no greater than 5:1. In combination with the reclamation and topsoil handling <br />techniques, reduced slopes will minimize the potential for erosion due to accelerated sheet wash <br />or gullying. <br />Diversions will be designed according to accepted design criteria, and will be built to minimize <br />erosion and prevent additional contributions of sediment by limiting the flow velocities and <br />Section 2.05.6(3) Page 5 October 2013 (TR -05) <br />E: \New Horizon \DRMS \NHN Permit \04_Technical Revisions TR \TR -05 \Documents from Jason \2.05.6(3) Protection of Hydrologic Balance TR- 05.doc <br />