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<br /> <br />large, but it mdy extend to a distance of 2 to 3 miles from the edge of <br />the mine workings. Because the underground workings lie 400 to 500 feet <br />below the portal areas, the piezometric surface of the mine water would <br />not be expected to rise to a level where it would intersect the ground <br />surface, thus causing discharges through the mine portals or shafts. <br />B. <br />There would be approximately twice as much ground water flow through the <br />flooded mine workings than existed through the undisturbed coal prior to <br />mining, The ground water flow would, however, be restricted by the <br />undisturbed coal, The ground water would stagnate and react with <br />fragmented roof, floor, coal, rock dust, and other materials within the <br />one cavity. Due to stagnation in the mine workings, water quality would <br />be of lower quality than that currently pumped from the underground <br />workings and similar to the quality of water measured at the New Elk Mine <br />coal processing waste pile (Exhibit 6, Table 13 ). The total dissolved <br />solids levels may equal or exceed 2600 mg/1, This mine water would <br />spread as a plume of degraded water down the dip of the rock strata which <br />is, in this case, downgradient. Based on the structural contours of the <br />coal seam, water passing through the flooded workings would move in a <br />northeasterly direction, It is anticipated that soluble materials would <br />be readily flushed, but the low permeabilities of the effected rock <br />strata downdip would slow the flow of water from the mine, causing the <br />flushing action to persist over a long time period, Since the coal seam <br />aquifer currently contains poor quality water, 806 to 1100 mg/1 total <br />dissolved solids, and is not used as a water supply in the general area, <br />the effects of mining on this aquifer will not materially damage the <br />quality of ground water used off-site. <br />Post-mining effects on the water quality in the stream/alluvial aquifer <br />system would be expected to be less than those occurring during <br />operations because mine water would no longer be discharged from the <br />underground workings. The postanining water quality impacts would be <br />limited to those produced by the Ciruela Canyon disposal pile. <br />The New Elk Mine <br />The effect of mining on the coal aquifer will be similar at both the <br />Golden Eagle and New Elk tdines. This assumption is justified given the <br />proximity of the mines, the similarity in geology of the overburden and <br />coals and the similarity of the mining operations. The effect of mining <br />on the coal aquifer will be the drawdown of the piezometric surface. The <br />drawdown of the piezometric surface from the Golden Eagle t4ine is <br />predicted to be slightly more than 1 foot, at a distance of 2 to 3 miles <br />from the mine workings. The area affected by the New Elk Mine dewatering <br />of the coal aquifer should be similar. Mine inflows are collected in <br />sumps and discharged into the Purgatoire River once suspended solids have <br />settled out. <br />_21_ <br />