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57 <br />• -' A search of the State records for information on registered wells in <br />the vicinity of the Maxwell Mine was conducted. A total of 31 wells were re- <br />corded, most of which are located in Section 30 T33S, R68W. The <br />well of record located nearest the Maxwell Mine is 3 miles from the <br />present mine. To the best of our knowledge, the Maxwell coal seam is not <br />utilized for water supply to any wells. Therefore, it is anticipated that <br />drawdown of the piezometric surface will have no adverse impact upon the <br />use of ground water from the bedrock in the region. <br />The recovery of the piezometric surface will occur in two stases. The <br />first stage is the relatively slow increase that will occur as the mine work- <br />ings are filled by ground-water inflow. Once the underground workings have <br />been filled, the piezometric surface will rapidly rise toward its eventual <br />steady state position. The inflow to the mine during the first stage of <br />recovery will be nearly the same as immediately prior to the cessation of <br />mining because the drawdown at the face will decrease only slightly as the <br />workings are filled. Assuming an area of 6 sq. mi., an average thickness of <br />9 ft., and a recovery factor of 0.65, the volume of workings to be filled <br />is lO9ft3. With an average inflow rate of 180 gpm (Case III), 79 years will <br />be required to flood the workings. The piezometric surface will then rise <br />rapidly because of the small storage coefficient. <br />The existence of the mine workings will permanently modify the pattern <br />of•ground-water flaw through the coal seam. The flooded mine constitutes a <br />region of essentially infinite permeability that will tend to cause ground <br />j water in the seam to preferentially pass through the working. The ratio <br />of the post-mining discharge through a circular area (plan view) of modified <br />i permeability Ki to the discharge through the same area with permeability Ko <br />before mining is (Mc'Whorter, et al., 1979) <br />Qa 2 <br />Qo - l+KO~Ki <br />In the case of the Maxwell Mine, the permeability Ki of the mine working <br />will be effectively infinite and there will be approximately twice as much <br />• _ flow through the flooded mine workings than existed through the same area <br />i <br />~ prior to mining. <br />