Laserfiche WebLink
Wetlands have also been identified within the permit area. Based on • <br />inspection of conventional and infra-red aerial photographs and <br />reconnaissance-level field investigation, there are estimated to be <br />approximately 77 acres of wetlands in the permit area. Most of the <br />wetlands are found in drainage channels, although there are small, <br />isolated wetlands on the hillsides where springs and seeps occasionally <br />emerge as a result of landslides/sumps. <br />2. Probable Hydrologic Consequences <br />Section 2.05.6(3) of the permit application contains the applicant's prediction <br />of the probable hydrologic consequences from mining and reclamation <br />activities at the West Elk Mine. <br />During the first two permit terms, the operator mined the F Seam. During the <br />third through fifth permit terms, MCC mined the B Seam exclusively. <br />Activity in these seams involve longwall mining methods, with very little or <br />no activity in the F Seam. During the current permit term, MCC will be <br />conducting development and longwall mining in the B-seam and the E-seam. <br />The Probable Hydrologic Consequences section of the permit is divided into • <br />two main subsections: Groundwater Effects and Surface Water Effects. <br />a. Ground Water Effects <br />During mining at the West Elk Mine, ground water seeps into the <br />underground workings from rock exposed in the workings. Inflow into <br />the workings was estimated to be a total of 166 acre-feet in 2004. Excess <br />accumulations of this water are pumped out of the workings into <br />Sylvester Gulch through a permitted discharge outfall. After mining is <br />completed, pumping will cease, the portals will be sealed, and the <br />underground workings will flood with the water seeping into the <br />workings. The operator estimates it will take between 200 to 800 years <br />for the workings to fully flood. The water that seeps into the workings <br />will saturate the gob in the downdip end of the workings and minerals <br />will be dissolved from the gob, creating a gob leachate. This leachate can <br />be expected to be alkaline and have TDS between 1,000 and 5,000 mg/1 <br />(for comparison, North Fork alluvial water probably has TDS greater <br />than 1,500 mg/1, based on monitoring at the Bear No. 1 Mine.) <br />As the downdip end of the West Elk Mine workings fill with gob <br />leachate, this leachate will exert a hydraulic head on the downdip walls of <br />the workings and the leachate may seep into the cleat porosity and fault is <br />porosity that is in the coal seams exposed in the workings. This leachate <br />could flow downdip, parallel to bedding,, through the coal seams and <br />33