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1 silt/clay interval at the top of the sequence is a slight aquatard, and following the installation Of most of the monitoring wells, groundwater levels rose 1 to 2 feet from the lower sand into this interval. ' 3.2 Depth to Groundwater The depth to groundwater has fluctuated by several feet since 1987 due to seasonal ' variations. Initially, the depth was 50 feet, but fell to more than 60 feet by November 1991. Water levels continued to remain depressed through 1992, but began to rise as precipitation returned to normal levels during the 1992-1993 rainy season. Groundwater reached a depth of 55 feet in April 1993, but has since fallen to approximately 60 feet again. 3.3 Groundwater Gradient The direction of groundwater flow has changed considerably at this site. As noted in section 2.6 above, the gradient was to the northeast in 1987, presumably due to the effects of ' pumping of municipal well #1, althoug a more eastward gradient would be predicted. Since municipal well #1 was shut in, groundwater flow has returned to the regional southwestward direction (Figure 6). However, there was a mound in the gradient in October 1993, due to the anomalous elevation of the water table in MW-1. The water table in MW-1 appears to be about 0.15 feet higher than expected. This produces a slight trough in the gradient in the vicinity of MW-4. This anomaly is unexplained at the present time. 3.4 Aquifer Properties 3.4.1 Theory and Methods 4 Slug tests can be performed either by rapidly withdrawing a volume of water from the well or by rapidly adding a volume to the well. Both methods were used at this site. A pressure transducer hung near the bottom of the well measured the pressure exerted by the overlying water column. As the Leight of the column changed following withdrawal or injection, the 1 transducer reported the change in hundredths of an inch. Measurements were made at 2- second intervals during the test. The time required for the water level to recover to its pre- test level is a measure of the rate at which water flows through the aquifer. ' The test was performed on MW-1, MW-4, MW-6, and MW-7. MW-2 and MW-3 were not ' tested because they are screened above the present water table. For the injection test, approximately one gallon of distilled waterwas added; for the withdrawal test, approximately one bailer volume was withdrawn. ' 3.4.2 Recovery Curves ' Data were automatically transmitted from the pressure transducer to a Data Logger in the field. The data were stored for later use in graphing the rate of change in water column Gw69-1 Audit 5ery..Inc ABA PAN/1.2g-94/1.47 17