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l • aquifer sand and the underlying clay bed, but is at the base of the screened interval in VT-1 and SW-1 Neither well was measured or sampled Figure 3 illustrates the groundwater gradient and general direction of groundwater flow The water table slopes to the east at a gradient of 0 0009 ft/ft This is a relatively flat gradient in comparison to previous quarters 4.2 Analytical Results Total Petroleum Hydrocarbon and BTEX concentrations stayed at or below the detection limits in VM-3 and VM-4, and declined,sharply in VM-2 (Table 2) This is the first time in several quarters that the TPH-g concentration fell below 10,000 µg11 (parts per billion—ppb) in VM-2 In VM-1,the TPH-g concentration rose from below the detection limit of 50 ppb in December,2000 to 670 ppb Except for VM-2, the concentrations are generally similar to those seen during the fourth quarter, and are probably reliable The magnitude of the decline in VM-2 is so large, however, that some of the decrease might be due to the fact that the well was not purged before it was sampled At several other saes, we have noticed no relation between hydrocarbon concentrations and purging, and therefore have recommended that the frequency of purging be reduced It may be necessary to perform standard purging procedtues in VM-2 to obtain samples that are truly representative of groundwater quality in the vicinity of the well 5.0 CONCLUSIONS AND RECOMMENDATIONS Groundwater monitoring should continue at this site through the rest of the year to verify the trend of declining hydrocarbon concentrations that has been reported recently We also recommend moving forward with the drilling of additional off-site wells as soon as the sidewalk along Grant Street has been replaced and an Encroachment permit can be obtained from the City After those wells are installed, it should be possible to complete a Problem Assessment Report and to delineate the full extent of groundwater contamination Due to the relatively dry winter and limited rise in the static water level, we do not recommend attempting to conduct an air sparging feasibility test of SW-1 Further, if groundwater quality continues to improve, it may not be necessary to test other remedial methods such as soil vapor extraction 3