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while minimizing disturbance. All temporary diversions will be removed and reclaimed • <br />after mining activities are completed. <br />Drainage from haulage and access roads will be routed to the nearest pond when not <br />exempted by the regulations. Culverts will be designed and constructed using approved <br />engineering design criteria where they are necessary to minimize erosion and prevent the <br />contribution of additional sediment to runoff. <br />Surface Yater Cuantity. The Surface 4ater Control Plan (Exhibit 13-2, Tab 13, <br />Facilities) describes pored diversion and culvert locations that will control all drainage <br />into, through, and out o~f the Yoast complex. The plan has been developed to ensure that <br />changes in surface water quantities are minimized. Impact of the designed structures <br />proposed et the Yoast complex (sediment ponds, diversions, culverts, etc.), and the <br />establishment of reclaimed areas within each mining area were determined to have no <br />significant affect on surface water quantity (see Tab 17, PRC). <br />All sediment ponds have been designed according to acceptable engineering criteria to <br />contain the 10-yeer, 24-hour runoff volumes. SCC will ensure that each pond maintains • <br />this capacity by dewatering and/or excavating excessive sediment accumulated according to <br />plans outlined in Tab 13 (Facilities). <br />The 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 <br />will ensure that runoff originating within or outside each mining area will be controlled <br />and adequately routed through [o minimize changes in surface water quantities. <br />The postmining landscape is designed to protect the hydrologic balance by establishing <br />slopes that generally mimic premining hillslopes, with some moderate reductions. Any <br />highwell reductions will result in maximum slopes not to exceed 3:1 except in areas where <br />the natural slope is steeper than 3:1. Reclaimed hillslopes established at the Yoas[ <br />mining area approximate the original premining contours. <br />Topsoil material will exhibit infiltration rates generally similar to or slightly greater <br />than premining soils. At the Yoast Mine, proposed reclaimed areas' will be retopsoiled by <br />either direct haulage or from stockpiled topsoil piles, (redistributed stockpiled • <br />topsoil) disked and adequately reseeded in a timely manner to minimize overland flow <br />races and volumes. <br />6 <br />