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2. Underburden <br />All of the monitor wells completed in strata t~elow the Dakota • <br />coal were used to construct the water level-piezometric surfe~ce <br />contour map (Exhibit 3). For reasons previously discussed, monitor <br />well GW-N11 was not used in the construction of this map. <br />The ground water flow direction is front the northeast to the <br />southwest. The primary recharge area is north~aast of the mine <br />and secondary recharge occurs via leakage from overlying units. <br />Overburden discharge occurs locally where 'the water table <br />intercepts the ground surface as seen at Spoil :iprings #1 and #2 <br />and in the washes. Mining operations appear to Piave had no effect <br />on the underburden ground water piezometric surface. <br />D. Aquifer Tests <br />Four aquifer tests were performed at the Nucla mine during the <br />1986 summer field season. These tests were performed to better <br />understand the hydrogeologic characteristics of the shal]ow • <br />ground water system at and adjacent to the Nucla mine. <br />1. Aquifer Test Procedures <br />Monitor well GW-N14 completed in the Dakota Coal seam was <br />tested by slugging the well with a known volume of water. The <br />maximum height of the water level was recorded as was the <br />recovery rate to the static water level. Monitor wells G4!-N9, <br />N13, and N15 were planned to be tested and analyzed utilizing <br />standard single well aquifer test methods by which the <br />discharge (Q) is kept constant end the time drawdown <br />measurements are made in both the pumping and recovery phases <br />of the test. However, very low well yields and unpredictable <br />equipment malfunctions precluded the performance of this type <br />of test. Instead, the wells were pumped for only six to eight <br />minutes at a constant rate. Time and drawdown measurements <br />were taken in both the pumping and recovery phases of the test. <br />All depth to water measurements were recorded to the nearest , <br />78 <br />