PERMFILE59255 - Laserfiche WebLink

Home Browse Search

West Elk Mine Tt should be noted that there is no lazge capacity Bumping occurring, nor has any occurred in the F Seam mine workings. This is because there is only limited F Seam groundwater inflows (locations discussed below), limited physical space in which to store this water, and the dip of the workings is unfavorable for storage (i.e., water would flow down-dip and out of the mined panels). Small volume operational Bumping of colluvial F Seam groundwater inflows occur in two locations; (1) in the Sylvester Gulch fan portal, and (2} in the South Mains neaz the West Ells Mine portals. These two areas receive colluvial inflows from the roof during a few months in late Spring, during a wet yeaz. These inflows, along with any flows that may accumulate in the F Seam main entries from pipe leaks or other operational sources, aze collected in these small operational sumps and discharged to ponds MB-1 and MB-2R or directly to the North Fork or Sylvester Gulch. Groundwater Oua[ity Effects Potential effects on groundwater quality from mining may occur from interconnections between different aquifers and between aquifers and surface sources due to subsidence or mine de-watering. For example, subsidence cracks may act as conduits between aquifers or between aquifers and stream channels within the permit azea. However, no positive relationship has been established between subsidence fractures and water storage (Dunnrd 1976). To date, monitoring data have not detected changes in geochemistry attributable to aquifer interconnection from mining and subsidence. These findings appeaz to be due to the poor aquifer • characteristics of the Mesaverde Formatioq the small amounts of groundwater present (apart from that observed within the previously mentioned BEM and 14HG fault systems) and the relatively similaz water chemistry of the individual formations in which samples have been taken. A review of the chemical analyses historically obtained from monitoring well groundwater samples show there to be no anomalous changes in water chemistry that indicate effects from mining activities. Data presented in the AHRs confirm that the concentrations of parameters tested fall within the baseline limits established prior to mining. in some cases, TDS concentrations have been observed to increase after mining activities pass through the azea only to return to pre-mining concentrations after activities in the area lessen. This is likely due to the fine bedrock material generated during the caving and collapse of the roof behind the longwall operation. It is a common finding that longwall mining has little effect on groundwater quality or quantity. For example: "A network of monitoring wells at four longwall mine sites in Appalachia were monitored for the effect of mining on water levels, water quality and well yield. Two sites were located in stream valleys and the other two sites were located on hilltops. The depth to the mine seam ranged from 500 to 850 feet. • 2.05-249 Revised November 2004 PR/0