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• for water rights augmentation pumping that will meet effluent limitations and minimize erosion (Pages <br />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 criteria to <br />minimize erosion and prevent the contribution of additional sediment to 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 into, through, and <br />out of the Nucla Mine mining area. The plan has been developed for insuring that changes in <br />surface water quantities are minimized. The impact of designed sVuctures consVucted at the Nucla <br />Mine mining area (sediment ponds, diversions, culverts, etc.), and the establishment of reclaimed <br />areas within each mining area were determined to have no significant affect on surface water <br />quantity (see Tab 17, Probable Hydrologic Consequences). <br />Alf sediment ponds have been designed according to acceptable engineering criteria to contain the <br />10-year, 24-hour runoff volumes. Peabody will ensure that each pond maintains this capacity by <br />dewatering and/or excavating excessive sediment accumulated according to plans outlined in Tab <br />13 (Facilities). The bottom and sides of sediment ponds will be compacted to a sufficient density <br />• to prevent excessive leakage of pond water to the shallow aquifers. <br />The five diversions have been designed to pass the 10-year, 24-hour runoff volumes in accordance <br />with approved engineering design criteria. Culverts and road drainageways will insure that runoff <br />originating within or outside each mining area will be controlled and adequately routed through to <br />minimize changes in surface water quantities. <br />The postmining landscape is designed to protect the hydrologic balance by establishing slopes that <br />generally will not exceed 5:1. Any highwall reductions will result in maximum slopes not to exceed <br />5:1. Reclaimed hillslopes established at the Nucla Mine mining area approximate the original <br />premining contours. <br />Topsoil material will exhibit infilVation rates generally similar to premining soils. At the Nucla Mine, <br />established reclaimed areas have been disked and adequately reseeded, and future reclaimed areas <br />in both mining areas will be manipulated mechanically using chisel plowing and ripping of graded <br />and topsoiled areas in combination with timely reseeding to minimize ovedand flow rates and <br />volumes. <br />Surface Water Monitoring. Peabody has installed a network of surface water monitoring sites in <br />irrigation laterals, at sediment structure discharge sites (NPDES), in tributaries to Tuttle and Calamity <br />• <br />16-5 <br />