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Maumain Coal Compa~ry 1998 Annual Hydrology Report West E(k Mine <br />• The majority of mine water was pumped to the NW Panels sealed sump and ultimately <br />dischagged via the Lone Pine pipeline. Assuming that the storage in the NW Panels sealed sump <br />remained essentially constant (estimated volume of 375 acre-feet), the volume pumped into and <br />discharged from the NW Panels sealed sump was approximately 328 acre-feet. <br />The remainder of the water discharged from the mine (primarily from the F-Seam and prior to <br />the start-up of the Lone Pine pipeline) was sent to ponds MB-1 and MB-2R for treatment and <br />discharge to the North Fork. The combined discharge volume for ponds MB-1 and MB-2R was <br />approximately 299 acre-feet during WY97. This volume includes about 12 acre-feet of treated <br />effluent from the WWTP and stormwater and snowmelt runoff. <br />Water is added during dust suppression spraying for the longwall and for the continuous miner <br />operations. This water is approximately 1.5 percent by weight of the coal produced. With the <br />6.2 million tons of product and gob that left the mine workings in WY98, there was about 68 <br />acre-feet of water used. Other losses included added moisture to the ventilation air and <br />absorption into gob and floor materials. <br />The total volume of water leaving the mine during WY98 was 731 acre-feet, which is <br />approximately 96 acre-feet less than the volume of water that entered the mine during the same <br />period. There are a couple of possible explanations for the discrepancy. First, the diversions <br />from the North Fork into pond FW-1 are allowed to overflow and spill back to the North Fork. <br />These return flows are not measured, but could represent a substantial volume throughout the <br />water year. Second, measurements of the fault inflows were approximate and the location of the <br />• fault inflows was not constant <br />• <br />83i-031.500 age Wrig r aver ngineers <br />