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between mine workings and the subcrops. However, fractured <br />coals could allow ground water movement from the <br />glacial/alluvial aquifer to the mine workings. <br />The implications of these effects to water users in the area <br />are considered to be insignificant., No wells in the area to <br />be affected by the drawdowns are completed solely in the D or <br />E coal seams. In addition, the dip of the strata beneath the <br />Grand Mesa to the north causes the coal seams to become <br />deeper and more inaccessible downdip of the mine. At the <br />farthest extent of the predicted drawdowns, the seams are <br />several thousand feet deep. Therefore, the resultant impact <br />produced by the mine's dewatering practices is considered to <br />be insignificant. <br />It should be noted that these predictions assume that <br />significant subsidence or fault induced inflows do not occur. <br />No major faults have been identified in the mine area. The <br />applicant's limited coal extraction method is designed to <br />prevent significant subsidence. Any subsidence effects are <br />expected to be minor and easily reparable. Therefore, it is <br />reasonable to assume that subsidence and faults will not <br />cause .s ignif icant inflow problems in the mine. <br />There is also a potential for the water quality in the three <br />aquifers to be impacted as a result of mining. This has <br />already occurred in some of the old workings near the <br />existing E seam mine. Water in these old workings has been <br />monitored with a TDS concentration of about 10,500 mg/1 and <br />an SAR of 27. This is extremely poor quality water. It is <br />possible that the water quality in the new mines will be <br />equally as degraded. <br />Once the coal seam aquifers are reestablished, when the <br />workings have filled with water after cessation of mining, <br />discharge will probably again be to the glacial/alluvial <br />aquifer through the coal seam subcrop. The applicant has <br />calculated that the flow through the glacial/alluvial aquifer <br />is about 1.53 cfs. Assuming that the discharge from the coal <br />aquifers will be equal to the mine inflows, about 0.11 cfs <br />will be discharging from the two coal seams into the <br />glacial/alluvial aquifer. According to this scenario, the <br />discharge from the two coal seams represents about 7 percent <br />of the total flow in the glacial/alluvial aquifer. <br />A mass balance analysis conducted by the Division predicted <br />that the resultant post-mining TDS concentrations in the <br />glacial/alluvial aquifer would be about 900 mg/1. The <br />pre-mining TDS concentration in the aquifer averaged about <br />330 mg/1. This increase of 570 mg/1 is probably a worst <br />case. The assumptions and variables used in the analysis are <br />the same as those used by the applicant to predict <br />20 <br />