Laserfiche WebLink
This plan calls for the construction of several engineered seals located <br /> within the mine designed to withstand pre-mining head pressures. <br /> MCC has conservatively estimated that the B Seam mine, including <br /> Jumbo Mountain, and the existing F Seam mine would flood and fill <br /> in 139.6 years. This estimate assumes no seepage or outflow and the <br /> worst case maximum steady inflow for the F Seam mine and the <br /> median of the 5-year and life-of-mine, worst case maximum steady <br /> inflows for the B Seam mine. <br /> Water moves downslope and discharges as seeps and springs. It also <br /> appears that mine inflows are controlled by the amount of precipitation <br /> (mostly snowmelt), depth of overburden and location and extent of <br /> fracture zones and not by the extent of the underground workings. <br /> Mountain Coal Company predicts that the West Elk Mine will have no <br /> significant impact on the quality and quantity of ground water and <br /> springs. Representative water quality samples from wells located in <br /> the lower coal member show that ground water is suitable for <br /> discharge to the North Fork. <br /> The B Seam, which will be mined during the next five year permit <br /> term, lies ten feet above the Rollins Sandstone unit. The operator <br /> states that based on data from the mining and reclamation plan and <br /> recent drilling, it is reasonable to assume that the North Fork of the <br /> Gunnison River recharges and receives discharge from the Rollins <br /> Sandstone in a small area on the northern edge of the West Elk <br /> property. It is evident from available data that the Rollins behaves <br /> similarly to the Barren member and Coal members in the permit area <br /> except the extreme northern edge where it has an alluvial contact with <br /> the North Fork. Ground water pore pressure is expected to be 100 <br /> feet above the Rollins Sandstone in the permit area. Since there is a <br /> unit downward gradient, mining in the B Seam will not impact the <br /> Rollins Sandstone. <br /> The Rollins Sandstone is considered a marginal aquifer in terms of <br /> yield and water quality and, to MCC's knowledge, has no points of <br /> usage in the mine vicinity. Review of data for the region indicates <br /> that none of the other mines in the area have monitored the Rollins <br /> Sandstone. Since the Somerset Mine has been active since 1906, any <br /> potential for severe water quality impact would probably be evident by <br /> this time. The water quality data for R-1, a well completed in Rollins <br /> Sandstone and drilled by Mountain Coal Company in 1976, indicates <br /> total dissolved solids generally outside the range acceptable for <br /> drinking water. MCC has completed a well to the Rollins Sandstone <br /> in the Jumbo Mountain area, which should provide some additional <br /> information to allow a more accurate description of this formation. <br /> 30 <br />