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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 />Topsoiling handling procedures (Section 2.05.4(2)(d), Topsoil (Redistribution)) and <br />revegetation methods (Section 2.05.4(2)(e), Revegetation) have been developed to stabilize the <br />landscape, prevent erosion, and minimize the additional contributions of sediment to runoff. They <br />include: the seeding of temporary disturbance and topsoil piles; mulching, chisel plowing and <br />deep ripping; cover cropping; and timely reseeding of reclaimed areas (regraded and topsoiled) <br />with seed mixes designed for rapid establishment and development of effective hydrologic cover. <br />Those areas that are affected by mining will be graded to postmining 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 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 <br />diversions will be removed and reclaimed after mining activities have been completed. Plans <br />have been developed for water rights augmentation pumping that will meet effluent limitations <br />and minimize erosion. Drainage from haulage and access roads will be routed to the sediment <br />pond. Where necessary, culverts will be designed and constructed using approved engineering <br />design criteria to minimize erosion and prevent the contribution of additional sediment to runoff. <br />Surface Water Quantity <br />Map 2.05.3(3)-1 details pond diversion and culvert locations that will control all drainage into, <br />through, and out of New Horizon 2 mining area. The plan has been developed for insuring that <br />changes in surface water quantities are minimized. The impact of designed structures proposed <br />for the New Horizon 2 mining area (sediment pond, diversions, culverts, etc.), was determined to <br />have no significant effect on surface water quantity (see Probable Hydrologic Consequences at the <br />end of this section). <br />The sediment ponds have been designed according to acceptable engineering criteria to contain <br />(at a minimum) the 10 -year, 24-hour runoff volumes. WFC will ensure that the ponds maintain this <br />capacity by dewatering and/or excavating excessive sediment accumulated according to plans <br />outlined in Section 2.05.3(3), Mine Facilities. The bottom and sides of the sediment pond will be <br />compacted to a sufficient density to prevent excessive leakage of pond water to the shallow <br />aquifers. <br />July 2016 (TR -74) 2.05.6(3)-5 <br />