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-32- There would be approximately twice as much ground water flow through the flooded mine workings than existed through the undisturbed coal prior to mining. The ground water flow would, however, be restricted by the undisturbed coal. The ground water would stagnate and react with fragmented roof, floor, coal, rock dust, and other materials within the one cavity. Due to stagnation in the mine workings, water quality would be of lower quality than that currently pumped from the underground workings and similar to the quality of water measured at the Allen Mine coal processing waste pile (Exhibit 6, Table 13). The total dissolved solids levels may equal or exceed 2600 mg/1. This mine water would spread as a plume of degraded water down the dip of the rock strata which is, in this case, downgradient. Based on the structural contours of the coal seam, water passing through the flooded workings would move in a northeasterly direction. It is anticipated that soluble materials would be readily flushed, but the low permeabilities of the effected rock strata downdip would slow the flow of water from the mine, causing the flushing action to persist over a ]ong time period. Since the coal seam aquifer currently contains poor quality water, 806 to 1100 mg/1 total dissolved solids, and is not used as a water supply in the general area, the effects of mining on this aquifer will not material damage the quality of ground water used off-site. Post-mining effects on the water quality in the stream/alluvial aquifer system would be expected to be less than those occurring during operations because mine water would no longer be discharged from the underground workings. The post-mining water quality impacts would be limited to those produced by the Ciruela Canyon disposal pile. 6. The Allen Mine A water balance study was conducted for the Allen Mine waste pile site and is contained in Exhibit 6 of the Allen permit application. In this study, the applicant has calculated the average annual precipitation at the Allen Mine to be 16.92 inches. Sublimation of snow during winter, and evaporative losses were calculated to be 3.77 inches. During a normal year, runoff from the refuse piles is calculated to account for all of the remaining available precipitation. Based on the calculations included in the application, deep percolation in most years will be essentially zero; that is, all precipitation will evaporate or runoff from the soil. During wet years, as much as .72 inches of water may be attributed to subsurface runoff (See Exhibit 6, pages 44-50 of the permit application). The affect of mining on the coal aquifer will be similar at both the Maxwell and Allen mines. This assumption 1s justified given the proximity of the mines, the similarity in geology of the overburden and coals and the similarity of the mining operations. The affect of mining on the coal aquifer will be to drawdown the piezometric surface. The drawdown of the piezometric surface from the Maxwell Mine is predicted to be slightly more than 1 foot, at a distance of 2 to 3 miles from the mine workings. The area affected by the Allen Mine dewatering of the coal aquifer should be similar. Mine inflows are co]]ected in sumps and discharged into the Purgatoire River once suspended solids have settled out.