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Mountain Coa! Companv 1999 Annual Hydrology Report R'es~ Elk Mine <br />The majority of mine water was pumped to the NW Panels sealed sump and ultimately <br />• discharged 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 373 acre-feet. <br />The remainder of the water discharged from the mine was sent to ponds MB-2R and MB-3 <br />(during maintenance on MB-2R) for treatment and discharge to the North Fork. The discharge <br />volume for ponds MB-2R and MB-3 was approximately 155 acre-feet during WY99. This <br />volume includes about 7 acre-feet of treated effluent from the WWTP and stormwater and <br />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 />7.1 million tons of product and gob that left the mine workings in WY99, there were about 78 <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 WY99 was 679 acre-feet, which is <br />approximately 22 acre-feet more than the volume of water that entered the mine during the same <br />period. This difference is well within the accuracy of the mine water balance, especially <br />considering that the fault inflows were estimated and the location of the fault inflows was not <br />constant. In addition, several of the ponds receive and discharge water that does not originate <br />from the mine. These sources included stormwater runoff and, in WY99, water resulting from <br />• the shaft cnnctruction in Sylvester Gulch. <br /> <br />831-031.510 Page21 R'righi fl'aterEngineers <br />