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Analysis of the Centerville #2 (512748) March 9, 1998 and #1 (511091) March 11, 1998 Pumping Tests Prairie du Chien - Jordan Aquifer Introduction The MDH was requested to assist in the delineation of wellhead protection areas by the City of Centerville, Minnesota, around the public water supply wells serving the community. An important part of the delineation process is to determine aquifer properties at the well site as accurately as possible. This is normally accomplished by performing a pumping test. Because of the need to test most public water supply wells, the MDH agreed to help with the pumping test as a part oftechnical assistance for communities, and program and staff development. The pumping test conducted by the MDH at the Centerville Well #2 was conducted as described below. There were problems in conducting the test in that wells cycled on during the test and disrupted the start of pumping and the end of recovery. The data were analyzed using standard nonequilibrium and semisteady-state methods, cited in references. Data plots are included in Appendix 1, field data sheets in Appendix 2, and test results are summarized on Table 1. The analysis shows that the aquifer responds as generally expected from the geologic setting. Description of the Test A pressure transducer was not placed in the pumping well because of a lack of access. A transducer was placed in Well # 1 (511091) on March 6, 1998 15: 1 0 to obtain background readings and to verify that draw down from Well #2 could be observed. Well #2 (512748) was turned off at about 14:00 on March 8, 1997 providing an eighteen hour resting period before the start of the test. There were no other nearby pumping wells to cause interference during the test. The observation well started pumping at 8:45 for five minutes. The start of the test was distorted by the recovery of this short pumping period. The test started at 09:10:05 on March 9,1997. Well #2 (512748) was pumped at an average rate of 55 1 gallons per minute as shown by the flowmeter on the well. The high pumping rate of 620 gallons per minute declined to 500 gallons per minute through the test as the water tower filled. This caused distortions in the later time pumping data. The pump was turned off at 08:30:05 on March 11, 1997 to start the recovery period. The recovery went to the full 24 hours and full recovery was achieved at the monitoring well. The pumped well cycled twice during the recovery distorting the later time recovery data. Because of the problems encountered during the test of Well #2 (512748) a short test of Well #1 was performed to confirm test results and to investigate the leakage that could not be observed in the first test. Well #1 was pumped for one hour at a rate of617 gallons per minute starting at 8:45:00 on 3/11/98 until 9:45:00. The recovery period extended until 12:25 on 3/12/98. No observation wells were used. Summary of Results