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2.04.5 page 5 <br />C.F.NF.RAT. <br />HYDROLOGY DESCRrpmrON <br />The Icing Coal Mine operation has little impact on groundwater <br />systems and its impact on the surface hydrology is moderate. <br />Future operations in the upper menefee coal seam are not expected <br />to disrupt aquifers, streams, water systems, or the small watershed <br />(up-slope areas of the mine site). See Section 2.04.7, pages <br />11-18. Hydrologic data obtained from the existing mine workings, <br />core drill holes in the mine plan area, and other research studies <br />show that the mining operation has had only a mild impact on water <br />sources of Hay Gulch. <br />The mining bench is located in the upper reaches of the Hay <br />Gulch drainage system. All wells, diversion ditches, sedimentation <br />ponds, water conveyances and storage, and the surface facilities <br />are shown on Map C-4, the mine surface drainage map. <br />Surface Hydroloav <br />Map C-4 shows the runoff flows in the mine plan area and the <br />permit area. Most of the surface runoff from the up-slope areas <br />(above the disturbed area) finds its way into the two gullies on <br />the east and west of the drainage system. From the gullies it is <br />routed via open channels and buried culvert pipe to the Hay Gulch <br />meadow north of the mine site. The west sediment pond, which has <br />a 2.5 acre foot capacity can not handle all the runoff that could <br />be expected from a ten year-twenty four hour storm event (about 1.6 <br />acre feet off the up-slope areas). The sediment pond(s) will <br />handle mostly water and sediment draining the permit area. <br />Map C-4 shows the completed open channel and culvert <br />construction. All east up-slope runoff water from the undisturbed <br />surface is diverted around the east side of the mine area. Runoff <br />water from a small drainage on the west side is diverted to the <br />west sediment pond along with disturbed runoff from a portion of <br />the facilities area. <br />Although the ponds have never overflowed, the completed <br />channels allows the up-slope runoff to by pass the disturbed permit <br />area and flow into the meadow. There will be no effect <br /> <br />