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3.0 RESULTS 3.1 Groundwater Gradient and Flow Direction Depth-to-groundwater measurements and calculated groundwater elevations are presented in Table 1 Results from previous monitoring events are included for comparison The static water level is several inches deeper than it was last year at this time, and more than 3 feet deeper than it was in April 2000 With an average depth of 48 7 feet below grade, the static level is near the base of the Modesto aquifer The calculated water table elevations were used to construct the groundwater gradient map in Figure 3 A southeastward slope is apparent, but the gradient is not planar The static water level in GT-10 is approximately 2 inches higher than would be expected from the overall gradient, forming a slight mound in the water table This is a reversal of the situation in the first quarter, when the water table was slightly depressed around GT-10 This probably confirms our suggestion in the previous report that well GT-10 responds slowly to rising or falling water levels because it is not screened within the Riverbank aquifer Hence, the water level was low in GT-10 as the static water level rose in the first quarter, and high in as the static level fell during the second quarter 3.2 Analytical Results Hydrocarbon concentrations are low or below detection limits in all wells except GT-10 (Table 2) This is the only well in which the static water level is within the screened interval and concentrations are representative of true conditions In most of the other wells, the concentrations are representative of conditions 15-25 feet below the static water level Figure 4 tracks gasoline and diesel concentrations in GT-1 since 1994, and Figure 5 shows the changes in water depth during the same period Concentrations peaked in the first quarter of 1995 and 1999 and the third quarter of 1999, but these peaks are apparently not related to the static water level, which has risen steadily for more than five years It is also apparent from Table 2 that concentration changes have not been urnform in all wells, while concentrations rose in some wells, they declined in others during the same quarter Hence, there is still no clear pattern or explanation for the observed changes in concentration, and it is not possible to predict when concentrations will decrease to non-detectable levels 4.0 CONCLUSIONS AND RECOMMENDATIONS The groundwater gradient and flow direction continue to fluctuate over a large range of compass directions A northward flow direction has been measured during the first quarter in more than one year, but the flow direction has tended to reverse and become southward or westward later in the year This pattern holds true for the second quarter of 2000, and the flow direction is presently to the southeast 3