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<br />NNG-21 <br />Due to the size of the well casing in NNG-21C and the size of the open <br />hole at NNG-21, a conventional pump test could not be conducted, that is, a <br />test in which a pump is installed and the drao-r down is observed in an obser- <br />vation well. The method used in obtaining the test data (i.e., a flowing <br />well) provides good re suits as long as the areal extent of the tested aquifer <br />is so large that the performance of the aquifer is not affected by the flowing <br />well except in the area of the test. The size of the synclinal basin and the <br />extent of the recharge area associated with the aquifer tested indicate that <br />this is a valid assumption. <br />Data collected from the pump test conducted at NNG-21 has given a <br />a <br />reasonable value of the aquifer transmissivity. The calculated storage <br />coefficient appears to be slightly high for a confined aquifer; hovrever, since <br />this fs a very difficult parameter to obtain, it is our opinion that a second <br />test is not warranted. <br />It should be noted that specific coal seam water problems will develop <br />as mining is progressed down dip toward the synclinal axis. Seam specific <br />aquifer studies should be conducted to determine the amount of water that <br />may be expected during mining operations in these areas. <br />If further consultation is desired, please do not hesitate to call. <br /> <br />Fi~M. FOX & ASSOCIA ES, INC. <br />p ~isieR • 9 <br />..~ p r'~~ fo'•,'P~ <br />Regan A. Heath * 'A 14395 `= <br />Geological Engineer :~ <br />RAH/cae 9t~s~F CQ`~~~o <br />Copies: 3 <br />Revi wed by: /~~~ <br />lX/!/C^ <br />Donald R. Clark, P.E. <br />Division Manager <br />-4- <br />