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The impact of sediment ponds and runoff from reclaimed areas on the quality of receiving streams was <br />found to be insignificant for Seneca II-W and Seneca II-W South mines(see Tab 17, PHC). Based on <br />past water quality monitoring at Seneca II and II-W, it is anticipated that no treatment of pond effluent • <br />will be necessary. However, should it become necessary to treat pond effluent, SCC will commit to <br />designing treatment facilities or procedures to handle the equivalent of a 10-year, 24-hour effluent <br />volume. <br />Plans for sampling overburden and topsoil after backfilling and grading have been developed, to identify <br />suitable and potentially deleterious materials, and are described in Tab 21 (Minesoil Reconstruction). <br />Based on these plans, surface runoff from reclaimed areas will not come in contact with materials that <br />would contribute to elevated levels of acid or toxic constituents. <br />Procedures for handling topsoil (Tab 21, Minesoil Reconstruction) and vegetation methods (Tab 22, <br />Revegetation Plan) have been designed to stabilize the landscape, prevent erosion, and minimize the <br />additional contributions of sediment to runoff. The primary procedures include the seeding of <br />temporary disturbance and topsoil piles, cover cropping, and timely reseeding of reclaimed areas <br />(regraded and topsoiled) with seed mixes designed for rapid establishment and development of effective <br />hydrologic cover. Some mulching, disking, or deep ripping may be used on steeper slopes, compacted <br />areas, or specialty planting areas. Areas affected by mining will be graded to postmining topographies <br />that generally feature slopes no greater than 5:1. In combination with the reclamation and topsoil <br />handling techniques, reduced slopes will minimize the potential for erosion due to accelerated sheet <br />wash or gullying. • <br />The Surface Water Control Plan (Exhibit 13-2, Tab 13, Facilities) includes four temporary diversions for <br />Seneca 11-W. Information pertaining to same for Seneca II-W South is also in Tab 13. All diversions <br />have been designed according to accepted design criteria, and are constructed to minimize erosion and <br />prevent additional contributions of sediment by limiting the flow velocities and tractive forces that <br />cause erosion. Temporary diversions in place longer than a growing season will be seeded with a <br />temporary seed mix as described in Tab 22. Diversions have been designed to maximize geomorphic <br />stability while minimizing disturbance. All temporary diversions will be removed and reclaimed after <br />mining activities have been completed. Plans have been developed for water rights augmentation <br />pumping that will meet effluent limitations and minimize erosion (Tab 13). <br />Drainage from haulage and access roads will be routed to the nearest pond when not exempted by the <br />regulations. Culverts will be designed and constructed using approved engineering design criteria <br />where they are necessary to minimize erosion and prevent the contribution of additional sediment to <br />runoff. <br />Surface Water Quantity. The Surface Water Control Plans (Exhibits 13-4 and 13-5, Tab 13, Facilities) <br />describe pond diversion and culvert locations that will control all drainage into, through, and out of the <br />Seneca II-W complex. The plan has been developed to ensure that changes in surface water quantities • <br />4 Revision 9/98