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additional contributions of sediment by limiting the flow velocities and tractive forces <br /> that cause erosion. Temporary diversions in place longer than a growing season will be <br /> seeded with a temporary seed mix as outlined in Tab 22. The diversions have been designed <br /> to maximize geomorphic stability while minimizing disturbance. All temporary diversions <br /> will be removed and reclaimed after mining activities have been completed. Plans have <br /> been developed for water rights augmentation pumping that will meet effluent limitations <br /> and minimize erosion (Pages 13-6 and 13-10 in Tab 13). <br /> Drainage from haulage and access roads will be routed to the nearest sediment pond. Where <br /> necessary, culverts will be designed and constructed using approved engineering design <br /> criteria 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, <br /> Facilities) detail pond diversion and culvert locations that will control all drainage <br /> into, through, and out of both the Nucla Mine and Nucla East mining areas. The plan has <br /> been developed for insuring that changes in surface water quantities are minimized. The <br /> impact of designed structures constructed at the Nucla Mine and proposed for the Nucla <br /> East mining area (sediment ponds, diversions, culverts, etc.), and the establishment of <br /> reclaimed areas within each mining area were determined to have no significant affect on <br /> surface water quantity (see Tab 17, Probable Hydrologic Consequences). <br /> All sediment ponds have been designed according to acceptable engineering criteria to <br /> contain the 10-year, 24-hour runoff volumes. Peabody will ensure that each pond <br /> maintains this capacity by dewatering and/or excavating excessive sediment accumulated <br /> according to plans outlined in Tab 13 (Facilities). The bottom and sides of sediment <br /> ponds will be compacted to a sufficient density to prevent excessive leakage of pond water <br /> to the shallow aquifers. <br /> The five diversions have been designed to pass the 10-year, 24-hour runoff volumes in <br /> accordance with approved engineering design criteria. Culverts and road drainageways will <br /> insure that runoff originating within or outside each mining area will be controlled and <br /> adequately routed through to minimize changes in surface water quantities. <br /> The postmining landscape is designed to protect the hydrologic balance by establishing <br /> slopes that generally will not exceed 5:1. Any highwall reductions will result in maximum <br /> slopes not to exceed 5:1. Reclaimed hillslopes established at the Nucla Mine and proposed <br /> 16-6 Revised 08/19/88 <br />