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West Elk Mine <br />Small volume operational sumping of colluvial F Seam groundwater inflows occur in two locations; <br />(1) in the Sylvester Gulch fan portal, and (2) in the South Mains near the West Elk Mine portals. <br />These two areas receive colluvial inflows from the roof during a few months in late Spring, during a <br />wet year. These inflows, along with any flows that may accumulate in the F Seam main entries <br />from pipe leaks or other operational sources, are collected in these small operational sumps and <br />discharged to ponds MB-1 and MB-2R or directly to the North Fork or Sylvester Gulch. <br />Groundwater Quality Effects <br />Potential effects on groundwater quality from mining may occur from interconnections between <br />different aquifers and between aquifers and surface sources due to subsidence or mine de-watering. <br />For example, subsidence cracks may act as conduits between aquifers or between aquifers and <br />stream channels within the permit azea. However, no posifive relationship has been established <br />between subsidence fractures and water storage (Dunrud 1976). <br />To date, monitoring data have not detected changes in geochemistry attributable to aquifer <br />interconnection from mining and subsidence. These findings appeaz to be due to the poor aquifer <br />characteristics of the Mesaverde Formation, the small amounts of groundwater present (apart from <br />that observed within the previously mentioned BEM and 14HG fault systems) and the relatively <br />similar water chemistry of the individual formations in which samples have been taken. <br />A review of the chemical analyses historically obtained from monitoring well groundwater samples <br />. show there to be no anomalous changes in water chemistry drat indicate effects from mining <br />activities. Data presented in the AHRs confirm that the concentrations of parameters tested fall <br />within the baseline limits established prior to mining. In some cases, TDS concentrations have been <br />observed to increase after mitiurg activities pass through the area only to return to pre-mining <br />concentrations after activities in the azea lessen. This is likely due to the fine bedrock material <br />generated during the caving and collapse of the roof behind the longwall operation. <br />It is a common finding that longwall mining has little effect on groundwater quality or quantity. For <br />example: <br />"A network of monitoring wells at four longwall mine sites in Appalachia were monitored for <br />the effect of mining on water levels, water quality and well yield. Two sites were located in <br />stream valleys and the other two sites were located on hilltops. The depth to the mine seam <br />ranged from 500 to 850 feet. <br />Pre-mining and post-mining water samples were collected from Wells 1 and 2 at Site 1 to <br />evaluate any changes in groundwater quality as a result of mining. The data showed that there <br />were no major changes. Site 2 revealed little appreciable change in groundwater quality due to <br />undermining, although it appeazs that hazdness and calcium decreased and sodium increased <br />after mining. At Site 3, there were no major changes in water quality although there were <br />increases in hazdness and sulfate after mining. At Site 4, water quality was not altered <br />appreciably" (Johnson 1992). <br /> <br />2.05-189 RevisedJeaee 2GbS PR10; Rev. Minch 1006; Rev May 2006PRt0 <br />