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• any users of underground water. First, water that had entered the mine through seeps <br />was collected in the northwest sump and was analyzed. The results of this analysis are <br />shown on page 59, which shows a total dissolved solids of 886 ppm and a pH of 7.8. <br />There are no ions of any concern in the water and the quality is similar to other <br />groundwater in the surrounding area. For this reason, predictions of the inflow rate, <br />recharge zones and rate of recharge from the mine are not important issues. <br />Second, the rate of inflow into the mine is relatively slow - 43 gallons per hour based <br />on the inflows shown on map page 65.03. Additional seeps on the northwest extension <br />probably increased this flow to approximately 50 gallons per hour although this is not <br />known accurately. Over a year, this rate would result in an inflow of 80 acre-feet of <br />water. <br />If an empirical analysis is made using a hydraulic conductivity of the roof and floor <br />material of 0.00025 ft/day, an effective porosity of 0.02 and a hydraulic gradient of 0.14 <br />ft/ft, [his results in an inflow of 12 acre-feet per year based on an exposed area of 64 <br />acres below the 7350 ft elevation level. On an overall hydrologic predictive scale, this <br />compares favorably with [he number reported above of 80 acre feet annually. This <br />scenario does not assume that water will enter the mine from the coal seam or the <br />sandstone zone that was exposed in the fault during the final mining extension. This is <br />possible since the lower Williams Fork aquifer is now saturated with groundwater, while <br />the mine workings were dry when initially driven. This implies that water from saturated <br />• aquifers that abut the mine workings will discharge into the mine until a hydrostatic <br />gradient is reached in the mine workings. Aquifers that abut the mine workings could <br />include all overburden, floor, and wall lithologies, including the coal itself and the lower <br />Williams Fork aquifer. <br />Assuming the inflow of 80 acre-feet per year and a mine storage volume of 256 acre- <br />feet, it would take 3.2 years to reach the 7350' level. Since the mine has been shut down <br />since the mid-1980's, this would have already occurred. <br />The next question to answer is where will this water discharge, if anywhere. It is known <br />that the water level in the Apex #1 Mine did fill to the 7355' level and reached <br />equilibrium. Discharge in general will only occur if a hydrodynamic gradient is <br />developed between the mine workings and any aquifer. This will require either recharge <br />into the mine workings at a higher rate than that which recharges into the aquifer, or the <br />development of a potentiometric "sink" in the aquifer due to water removal by a nearby <br />well. The only well which could produce a sink in the area of the mine is Well ID 46 <br />(See Surface and Groundwater Resources Map). However, this well has no reported <br />completion depth and flow rate. Also, as the mine fills [o the predicted 7355' level, any <br />well in this area should be unaffected. <br />The following possibilities for the water flow are presented below: <br />. 1) The water will enter the mine through [he sandstone fault as well as other seeps <br />Mid-Term Review 3/21(01 190.3 <br />