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5.2 Ground Water Gradient A ground water gradient map was produced from the data obtained from the December ' 19, 1997 sampling event (Figure 2). The elevations used in the calculation are summarized in Table 5. 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 5 Monitoring Well Water Elevations - December 19, 1997 ' Well Well Collar Depth to Water Ground Water Number Elevation (feet) Elevation (feet) (feet) ' MW-1 57.70' 11.11' 46.59' MW-2 58.82' 11.88' 46.94' MW-3 58.22' 11.30' 46.92 ' MW-4 57.46' 10.36' 47.10' MW-5 57.86' 11.46' 46.40' MW-6 57.27' 11.04' 46.23' MW-7 56.15' 9.43' 46.72' MW-9 56.60' 10.29' 46.31' �. 5.3 Discussion of Analytical Results Analytical laboratory data indicate essentially no change in detected constituent levels in monitoring well MW-1 as compared with the previous sampling event results. The sample collected from monitoring well MW-6 indicated a decrease of ethyl benzene from ' 2.0 4g/L to 0.5 µg/L. Benzene remained below detectable levels and toluene, total xylene and TPH gasoline dropped below detectable levels. All oxygenate compounds indicated non detectable levels in each of the sampled wells. These data confirm the non detectable oxygenate levels found during the previous sampling event. The remaining wells, MW-5, MW-7 and MW-9 each indicated non detectable levels for ' all analyzed constituents. These data are consistent with data obtained from previous quarterly sampling events. Monitoring well MW-8 was not sampled because intrusion of roots into the well. ' The bailer blanks for MW-1 and MW-6 indicate non detectable levels for all analyzed constituents. r American Geological Services, Inc. CA95DE-029 14