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After mining is completed at the West Elk Mine, the underground <br />workings may flood to a point where mine water discharges to the surface <br />either through a perpetual drain that MCC may construct at the downdip <br />end of the workings next to State Highway 133, or as seepage from the <br />coal outcrop on the hillside south of the highway (if the drain is not <br />constructed). The maximum discharge is predicted to be around 100 <br />gpm. The discharge would likely be relatively high in dissolved solids <br />(on the order of 1,500 to 5,000 mg/l total dissolved solids). The <br />maximum 100 gpm discharge would be diluted to near premining quality <br />by water in the North Fork of the Gunnison River, where flow is always <br />more than 4,500 gpm and total dissolved solids are less than 200 mg/1. <br />MCC predicts the quantity of its water use will not adversely affect the <br />hydrologic balance. Snowmelt provides most surface water flow in the <br />permit area. Mining activities will not have a significant effect on <br />snowmelt runoff. Overland runoff passes over disturbed areas within the <br />permit area to one of the eight sedimentation ponds, mentioned <br />previously in this section. This water may be discharged to the North <br />Fork or stored when water rights are in priority. <br />During Water Year 1982, MCC's conditional right to withdraw water <br />from the North Fork was deemed absolute. When this water right is in <br />priority, water can be pumped from the intake point to the 10 acre-foot <br />freshwater pond. This water right is expected to be out of priority from <br />July to September. Average withdrawals from the North Fork of the <br />Gunnison are not expected to exceed 400,000 gallons per day (gpd) and <br />are likely to be on the order of 200,000 gpd. The freshwater pond is <br />filled during spring runoff and kept full until water rights are out of <br />priority. The water is either treated to meet potable and sanitary water <br />requirements, used and then treated as sanitary waste water, or is <br />withdrawn for dust suppression in the mine and becomes mine water. <br />The potential effects of MCC's water diversion on North Fork flows have <br />been projected for flow rates and flow volumes. With the existing pump <br />capacity, 450 gallons per minute (gpm), the diversion would result in a <br />measurable change in flow during low flows having return periods of <br />about 200 years or greater, and would be less than 5 percent. During <br />extreme low flow periods, MCC's water rights would be out of priority <br />and diversion would not be undertaken. <br />Although subsidence fractures that develop over and next to mine <br />workings have the potential to dewater streams and ponds, Section <br />2.05.6(6) of the permit application explains this probably will not occur <br />because subsidence cracks that develop at the surface will not extend <br />deep enough to intersect fractures propagating upward from the caved <br />and fractured zones. Also, the stratigraphic sequence in stream valleys is <br />resistant to fracturing due to the presence of interbedded fine-grained <br />38