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<br />-29- <br />The applicant has estimated that inflow to the Maxwell Mine from the coal seam <br />and roof would be between 159 gpm and 193 gpm depending upon the average <br />transmissivity of the material encountered. This dewatering will create a <br />drawdown of the piezometric surface in the coal seam in and around the mine. <br />Drawdown of afoot or more could extend outward as far as 2 to 3 miles from <br />the Maxwell Mine (see Exhibit 6 of the Maxwell permit application). <br />Undermining of the Purgatoire River might be expected to deplete flow in the <br />stream/alluvial aquifer system. Using an estimated value of effective <br />vertical permeability of O.000Zi ft/d, the d~wnward flow of water from the' <br />body of alluvium was estimated to be 441 ft. /d or only 2.3 gpm. This <br />calculation was made for vertical leakage of surface water through the <br />overburden to the mine workings. The overburden strata acts as an aquitard, <br />restricting the downward movement of water. This small water loss from the <br />stream/alluvial aquifer system would have an insignificant impact on <br />Purgatoire River flows or alluvial ground water levels <br />An inflow study for the Maxwell Mine was conducted in November., 1983. This <br />study consisted of the mapping of all mine inflows, measuring or estimating <br />inflow rates, and determining inflow sources. The information on Maxwell Mine <br />inflows is contained in the WFC Submittal 3 and the Maxwell Mine Map submitted <br />December 1, 1983. <br />fault and fracture systems have not been encountered in the Maxwell Mine to <br />date. The applicant, however, anticipates encountering fault and fracture' <br />systems similar to those encountered in the adjacent Allen Mine. The faults <br />and fractures are dry in the Allen Mine and are anticipated to be dry in the <br />Maxwell Mine, as well. There are no mine inflows through the floor of the <br />Maxwell Mine. Therefore, the mine is not impacting underlying aquifers. <br />The largest point source mine inflows were 3 to 10 gpm from 2 air shafts and 1 <br />unsealed drill hole. These point source inflows are probably the result of <br />dewatering of overlying perched aquifers penetrated by the drill hole and air <br />shafts. The total mine inflow from point sources amounted to 16 gpm, or 53X <br />of the total mine inflow (30 gpm). The remaining mine inflows were from <br />weeping coal faces and weeping rock strata along the length of the rock slope <br />incline. These weeping areas contribute inflows approximating 14 qpm, or 47X <br />of the total inflow. These weeps represent dewatering of the coal aquifer. <br />The highest weep flows, totalling 11 gpm, are in the mine workings beneath the <br />Apache Canyon stream channel. Mine workings beneath the Ciruela Canyon <br />drainage only receive about 1 gpm from weeping coal faces. Development <br />mining, to date, is not significantly impacting the overlying stream/alluvial <br />systems. <br />The Maxwell mine has undergone only development mining. Thus, there has not <br />been any pillaring or longwall mining which would result in subsidence. There <br />are no subsided areas in the Maxwell Mine from which the quantity of inflows <br />resulting from subsidence can be measured. Empirical data on inflows to <br />mined-out areas is, however, available from the Allen Mine. The <br />