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<br />During operations, dewatering would occur in the coal aquifer and the <br />drawdown of the piezometric surface could extend outward to approximately <br />3 miles from each mine. Since the mines are adjacent to each other, a <br />portion of these affected areas would overlap. Within that zone, <br />drawdown effects would be additive. <br />After the cessation of operations, mine water would no longer be <br />discharged and the abandoned workings would fill with water. The ground <br />water Level and piezometric surface would partially recover. A permanent <br />depression in the piezometric surface of the coal aquifer would exist in <br />the vicinity of the flooded workings of the mines. The depression would <br />not be large, but it may extend 3 miles from each mine. Approximately <br />twice as much ground water would flow through the flooded mine workings <br />than flowed through the undisturbed coal prior to mining. This mine <br />water flow would, however, be restricted by the low permeability of the <br />undisturbed coal surrounding the mine workings. Ground water would <br />stagnate in the mine workings and react with fragmented roof, floor, <br />coal, rock dust, and other materials in the mine cavity. This ground <br />water would have a poorer quality than water currently pooped from <br />underground workings, which is similar to ground water observed in the <br />New Elk refuse pile. The total dissolved solids levels are expected to <br />equal or exceed 2600 mg/1 (Exhibit 6, Table 13 of the permit <br />application). This ground water would spread as a plume down dip. The <br />effect of having two mining operations affecting strata in hydrologic <br />communication with one another would be to decrease dilution within the <br />aquifers and increase the distance a detectable mine water plume would <br />spread. The degradation of water quality in the coal aquifers will not <br />impact ground water use in the general area, since the poor quality and <br />depth limited use originally. <br />The two operations are expected to cumulatively effect the flow in the <br />Purgatoire River stream/alluvial aquifer system. The New Elk Mine is <br />located on the Middle Fork of the Purgatoire River. This fork joins the <br />North Fork of the Purgatoire to form the Purgatoire River. The Golden <br />Eagle Mine is located adjacent to the Purgatoire River immediately <br />downstream from the New Elk IAine. Both operations have undermined and <br />will further undermine the stream/alluvial aquifer systems. The amount <br />of depletion of flow in the Purgatoire River alluvial aquifer has been <br />estimated to be 5 gpm for the New Elk Mine, and 2.3 gpm for the Golden <br />Eagle Mine. The combined predicted depletion of the stream/alluvial <br />system is 7.3 gpm (0.016 cfs) which amounts to approximately 0.1% of the <br />Q7-10 low flow in the Purgatoire River (10.9 cfs). This minor loss in <br />stream flow would be offset during mining by the discharge of mine waters <br />from the underground workings. The most current average discharge is 75 <br />gpm from the New Elk Mine, and 55 gpm from the Golden Eagle Mine. Full <br />development at the currently inactive New Elk Mine, however, could <br />increase mine discharge to 180 gpm; full development at Golden Eagle <br />could result in a discharge approaching 500 gpm. <br />_27_ <br />