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r3 0 CONCLUSIONS, RECOMMENDATIONS AND PROJECT STATUS s Between March 28 and May 21, 2002, the groundwater surface beneath the site dropped an average of 0 79 feet The groundwater gradient configured using the shallow-constructed wells decreased slightly from 0 00125 to 0 00120 foot/foot, and the flow direction shifted approximately 35 degrees to the north The groundwater gradient configured using the deep-constructed wells also decreased slightly from 0 0017 to 0 0015 foot/foot, and the flow direction shifted approximately ' 40 degrees to the northeast Since May 1992, the groundwater surface has risen approximately 26 5 feet Groundwater from Irrigation Well #2 did not contain detectable concentrations of any of the gasoline constituent compounds analyzed This represents nine consecutive quarters of no gasoline compounds in groundwater from Irrigation Well #2 ' Between March 28, and May 21, 2002, the concentrations of gasoline compounds in the groundwater monitoring wells have remained relatively consistent MTBE in groundwater appears to be limited to the groundwater table to the northeast (downgradient) of the former UST As shown on an isoconcentration map (Figure 6), the plume of groundwater impacted by MTBE is defined to the east at MW-4 and to the northeast at MW-8A and MW-8B Concentrations of MTBE in the wells nearest the former UST source area (MW-1, MW-2, MW-3, VW-1D and VW-2D) have declined significantly Concentrations of MTBE in the wells ' downgradient of the source area (MW-5, MW-6 and MW-7) increased initially and appear to have stabilized Based on these conclusions, Ramage Environmental recommends that the monitoring well network continue to be monitored and sampled on a quarterly basis to further monitor plume concentration and stability At the site, the sources of impacted groundwater have been removed and/or remediated, the plume of impacted groundwater has been delineated and appears to be stable, and nearby sensitive receptors do not appear to be threatened If concentrations of gasoline compounds remain stable over the next two quarters, the case should be considered for regulatory closure ' The next quarterly groundwater monitoring event is scheduled for August 2002 7 1