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The impact of a sediment pond and runoff from reclaimed areas on the quality of receiving streams <br />was found to be of minimal significance (see Probable Hydrologic Consequences at the end of this <br />section). Existing NPDES permit (CO- 0000213) has been modified to include 007. All terms and <br />agreements specified in the approved permit will be adhered to during the mining operation to <br />ensure that effluent will meet the permit limitations. Based on past water quality monitoring, it is <br />anticipated that no treatment of pond effluent is necessary. However, should the need for treatment <br />of pond effluent be demonstrated, WFC will commit to designing treatment facilities or procedures <br />to handle the 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 contribute <br />to elevated levels of acid or toxic constituents. <br />Topsoiling 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: the <br />seeding of temporary disturbance and topsoil piles; mulching, chisel plowing and deep ripping; <br />cover cropping; and timely reseeding of reclaimed areas (regraded and topsoiled) with seed mixes <br />designed for rapid establishment and development of effective hydrologic cover. Those areas that <br />are affected by mining will be graded to postmining topographies that generally feature slopes no <br />greater than 5:1. In combination with the reclamation and topsoil handling techniques, reduced <br />slopes will minimize the potential for erosion due to accelerated sheet wash or gullying. <br />Diversions have been 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 tractive <br />forces that cause erosion. Temporary diversions in place longer than a growing season will be <br />seeded with a temporary seed mix as outlined in Section 2.05.4(2)(e). Diversions have been <br />designed to maximize geomorphic stability while minimizing disturbance. All temporary diversions <br />will be removed and reclaimed after mining activities have been completed. Plans have been <br />developed for water rights augmentation pumping that will meet effluent limitations and minimize <br />erosion. Drainage from haulage and access roads will be routed to the sediment pond. Where <br />necessary, culverts will be designed and constructed using approved engineering design criteria <br />to minimize erosion and prevent the contribution of additional sediment to runoff. <br />Revised September 2014 (TR -64) 2.05.6(3) -8 <br />