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lie 5.2 Ground Water Gradient A ground water gradient map was produced from the data obtained from the October 15, 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 - October 15, 1997 I ' Well Well Collar Depth to Water Ground Water Number Elevation (feet) Elevation(feet) (feet) ' MW-1 57.70' 11.32' 46.38' MW-2 58.82' 12.00' 46.82' MW-3 58.22' 11.43' 46.79' MW-4 57.46' 10.68' 46.78' ' MW-5 57.86' 11.69' 46.17' MW-6 57.27' 11.32' 45.95' MW-7 56.15 9.61' 46.54' MW-9 56.60' 10.52' 46.08' ' 5.3 Discussion of Analytical Results Analytical laboratory data indicate a slight increase 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 slight increase of ethyl benzene, total xylene and TPH-gasoline. Benzene remained below detectable levels and ' toluene was similar to previous sampling events in monitoring well MW-6. 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. ' Laboratory data indicates that monitoring wells MW-1, MW-5, MW-6, MW-7, and MW- 9 contained no detectable limits of MTBE, Ethanol, tertiary-Butanol, DIPE, ETBE, or ' TAME. The bailer blanks for MW-1 and MW-5 indicate the presence of toluene at 0.5 µg/L. It is believed that the distilled water used to prepare the blanks is the source of the toluene. 1 . American Geological Services, Inc. CA95DE-U29 13