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<br />-25- <br />B. The New Elk Mine <br />A water balance study was conducted for the New Elk Mine waste pile site and <br />is contained in Exhibit 6 of the New Elk permit application. In this study, <br />the applicant has calculated the average annual precipitation at the New Elk <br />Mine to be 16.92 inches. Sublimation of snow during winter, and evaporative <br />losses were calculated to be 3.77 inches. During a normal year, runoff from <br />the refuse piles is calculated to account for all of the remaining available <br />precipitation. Based on the calculations included in the application, deep <br />percolation in most years will be essentially zero; that is, all precipitation <br />will evaporate or runoff from the soil. During wet years, as much as .72 <br />inches of water may be attributed to subsurface runoff (See Exhibit 6, pages <br />44-50 of the permit application). <br />The affect of mining on the coal aquifer will be similar at both the New Elk <br />and Golden Eagle mines. This assumption is justified given the proximity of <br />the mines, the similarity in geology of the overburden and coals and the <br />similarity of the mining operations. The affect of mining on the coal aquifer <br />will be to drawdown the piezometric surface. The drawdown of the piezometric <br />surface from the Golden Eagle Mine is predicted to be slightly more than 1 <br />foot, at a distance of 2 to 3 miles from the mine workings. The area affected <br />by the New Elk Mine dewatering of the coal aquifer should be similar. Mine <br />inflows are collected in sumps and discharged into the Purgatoire River once <br />suspended solids have settled out. <br />The applicant has predicted the maximum rate of inflow at the Golden Eagle <br />Mine to reach 180 gpm. Since dewatering of the coal aquifer at the New Elk <br />Mine has been occurring for a number of years, the maximum discharge is <br />predicted to be less than that predicted at the Golden Eagle Mine. <br />The average mine discharges measured in the third quarter of 1983 at the New <br />Elk Mine are higher than those measured when the hydrologic report in Exhibit <br />6 was prepared. The present discharge rate is 123 gpm, whereas the previously <br />reported discharge rate was 73 gpm. This increased discharge rate can be <br />attributed to the additional mining which occurred after preparation of the <br />hydrologic report and the present inactivity of the mine. The additional <br />mining resulted in increased area of inflow. During mining, water was <br />consumed as adsorbed water on coal exiting the mine, and in increased humidity <br />in the ventilation air. Currently, coal is not exiting the mine, and <br />ventilation air volumes are reduced. <br />Mining activity will affect the stream/alluvial aquifer system of the Middle <br />Fork of the Purgatoire River. The Allen and Maxwell coal seam aquifer <br />subcrops below the Middle Fork of the Purgatoire River and in Pete Canyon, <br />north of the New Elk Mine. These streams and their alluvial aquifers may <br />recharge the coal aquifer. The underground mine workings may deplete the <br />stream/alluvial aquifer systems through increased recharge at subcrops and <br />outcrops of the coal aquifers. Depletion of stream/alluvial aquifer systems <br />may also occur as a result of drying up of aquifer discharges (springs and <br />seeps). The applicant has predicted that the stream/alluvial aquifer system <br />will be depleted by vertical leakage of surface waters through the overburden <br />strata into the mine cavity. <br />