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Since the base of the E coal seam in the vicinity of No. 5 Mine <br />Well is above the current potentiometric level in this well, it is <br />not likely that the recent fluctuations in potentiometric levels in <br />the Trout Creek Sandstone is related to mine dewatering in the <br />overlying E and F coal seams. However, in the past when <br />potentiometric levels in the Trout Creek were higher and mining of <br />the F coal seam occurred further down dip at lower elevations, <br />dewatering of the coal could have reduced potentiometric levels in <br />the Trout Creek Sandstone. <br />This would require an upward flow in response to the gradient <br />created by mine dewatering. Upward flows may have occurred in the <br />vicinity of fault zones such as in the 2 West Main where water <br />quality monitoring of past water inflows to the No. 5 Mine along a <br />fault zone indicated an ion chemistry similar to ground water in <br />the Trout Creek Sandstone. <br />The water levels in the Middle Sandstone show fluctuations which <br />are apparently related to dewatering and subsidence associated with <br />Mines 5 and 6. The declines in the levels in Wells 81-01 and 83-01 <br />between 1988 and 1990 appear to have leveled off since the middle <br />of 1990. Water levels in these two wells and in Well TR-7A <br />measured during 1992 are similar to the levels measured in 1983 and <br />1984. The slight recovery from 1984 through 1988 is apparently the <br />result of a shift in the location of mining to an area further up <br />dip. Water level fluctuations since 1983 are greater in Well 81-01 <br />as compared to Wells TR-7A and 83-01 as would be expected since <br />this well is closer to the location of mine dewatering. <br />The water levels in Well 83-02 show a different pattern. The water <br />level decline of about 150 feet from 1987 to mid 1989 in Well 83-02 <br />is determined to be related to mine dewatering as Mine 5 workings <br />approached the location of the well. The more abrupt 200 foot <br />decline in water levels observed near the end of 1989 and beginning <br />of 1990 is thought to be a drawdown response due to subsidence as <br />its location is only a few hundred feet horizontally from an F seam <br />longwall panel which was mined in a similar time frame. <br />Wells TR-4 and 83-03 are located at greater distance horizontally <br />from the active operations for Mines 5 and 6. Water levels in Well <br />TR-4 appear to be related to the fluctuations observed on all three <br />of the downgradient Middle Sandstone Wells, 81-01, 83-01 and 83-02. <br />The water level decline in TR-4 prior to 1984 and the subsequent <br />recovery up to 1988 closely parallels the trends observed in Wells <br />81-01 and 83-01. The decline during the first part of 1991 also <br />parallels the trend in these two wells. However, the rapid decline <br />during the last part of 1989 and the first part of 1990 appears to <br />follow the trend observed in Well 83-02 although the magnitude of <br />decline is considerably less. <br />. 2 <br />