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During the past two permit terms, the West Elk Mine has mined <br />the F seam. During the next five years, West Elk will <br />primarily mine the B seam. Activity in this seam will <br />involve longwall mining methods, with very little activity in <br />the F seam. <br />The Probable Hydrologic Consequences section of the permit is <br />divided into two main subsections: Ground Water Effects and <br />Surface Water Effects. <br />a. Ground Water Effects <br />There are no immediate demands on ground water in the <br />vicinity of the West Elk Mine. Domestic water for the <br />mine will be supplied by surface water from the North <br />Fork of the Gunnison River, as there is limited <br />potential to use ground water as a resource. The <br />primary concern with ground water quality and quantity <br />is the possible impact on springs, the potential for <br />mine water discharge and ground water quality impacts <br />in the mine facilities area. <br />The underground mining methods in use at the West Elk <br />Mine can affect ground water in two ways. First, <br />development mining in areas where ground water is <br />present in or near the coal seam can cause localized <br />movement of this water into the mine workings. To <br />date, ground water movement of this type has occurred <br />in areas of low cover which are highly fractured (near <br />outcrops and near stream channels) and where sandstone <br />channels bearing water immediately overlie the coal <br />seam. Secondly, retreat mining can cause subsidence <br />and the fracturing of overlying ground water aquifers. <br />Again, water usually moves into the mine workings. The <br />permeability of the F seam and overlying strata is very <br />low and the areal extent and quantity of water stored <br />in these units is small. <br />Prior to construction of the mine, the applicant made <br />an estimate of mine inflow by using preliminary pump <br />test results and the McWhorter hydrogeologic model. <br />The mine flow estimates assist in identifying the <br />magnitude of mine discharge and to assess the potential <br />impact on natural patterns of ground water recharge and <br />discharge. <br />The operator at the West Elk Mine expects that mine <br />inflows will increase at a rate slower than the <br />McWhorter model predicted for advancing mine workings. <br />Most of the inflow has occurred along the subcrop in <br />the same location each year. The inflow is seasonal <br />and varies with the magnitude of seasonal <br />precipitation. Inflow to the advancing mine workings <br />has been minimal and unmeasurable. <br />-36- <br />