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5.2 Ground Water Gradient A ground water gradient map was produced from the data obtained from the December 2, 1996 sampling event (Figure 2). The elevations used in the calculation are summarized in Table 4. The ground water flow direction is toward the northwest during this sampling ' event. This gradient and flow direction is consistent with previous monitoring events. TABLE 4 ' Monitoring Well Water Elevations Well Date Well Collar Depth to Water Ground Water ' Number Elevation (feet) Elevation (feet) (feet) MW-1 12/02/96 57.70' 10.87' 46.83' ' MW-5 12/02/96 57.86' 11.33' 46.53' MW-6 12/02/96 57.27' 10.81' 46.46' MW-7 12/02/96 56.15' 9.16' 46.99' ' MW-8, 12/02/96 56.09' 1 9.32' 1 46.77' IL MW-9 12/02/96 56.60' 9.96' 46.64' ' 5.3 Discussion of Analytical Results Analytical laboratory data indicate a modest decrease in detected constituent levels in monitoring well MW-1. The sample collected from monitoring well MW-6 indicated a detectable level of benzene at 0.7 pg/L, the other constituent levels are virtually identical to those found during the previous sampling event. The remaining wells, MW-5, MW-7 MW-8 and MW-9 each indicated non detectable levels for all analyzed constituents. These data are consistent with data obtained from previous quarterly sampling events. ' 6.0 CONCLUSIONS ' The following conclusions and recommendations are based on the observations and analytical data collected to date. Site, soil and ground water conditions not discovered or currently known may cause a change in the opinions presented in this report. Laboratory analysis of ground water samples indicates the presence of moderate levels of gasoline and gasoline constituents in water collected from monitoring well MW-1 and ' low levels in MW-6. All other monitoring well samples indicated non detectable levels i A . merican Geological Services, Inc. ' CA95DE-029 ll