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§eo(ngica(Technus 2nc Page 5 Groundwater Monitoring Report Project No 425 2 August 15,2000 The results from the latest rounds of sampling are comparable with the results from the previous monitoring events The following observations are made • TPH-G concentrations in MW-1 are exhibiting an increasing trend for the last four events See Figure 3 for graph of Benzene and TPH-G versus time in MW-1 • Contaminant concentrations in MW-2 and MW-4 continue to fluctuate See Figure 4 for ' graph of Benzene and TPH-G versus time in MW-2 o MW-5 contaminant concentrations exhibit an increasing trend ' a MW-102 was non-detect for the fourth consecutive event O MW-202 was non-detect for the third consecutive event 9 All of the domestic wells were non-detect for the event 3.0 CONCLUSIONS AND RECOMMENDATIONS in the status of the groundwater at this The following conclusions have been drawn regarding g site and recommendations for future work Conclusions I The water table groundwater gradient historically flows in a northern direction at about 0 002 ft/ft However, over the past year and a half, the gradient has shifted towards the east The cause for this is not known at this time 2 The intermediate depth groundwater flows NW at approximately the same slope as the water table, which is consistent with previous monitoring events 3 Vertical groundwater gradients have been found to be flowing upward during early spring ' and downward during late spring and summer This may be due to the annual cycle of groundwater pumping needs of the community The upward flow of groundwater during certain portions of the year may be responsible for preventing these contaminants from ' significantly impacting the deeper aquifer zones 4 The shallow water table groundwater plume is laterally defined except to the west 5 Free-floating gasoline was not present in MW-2 in September and only droplets in ' December 1999, but typically is present in late fall and winter months 6 Petroleum hydrocarbon concentrations in the groundwater at the site fluctuate with each monitoring event MW-1 & 4 appear to be increasing 7 It appears that the deeper groundwater gradient is defined vertically since MW-102 and MW-202 are non-detect 8 The domestic wells associated with this site remain non-detect 9 With several domestic wells associated with the residences surrounding the property and the wells for the elementary school located a short distance northeast of this property, this groundwater plume appears to continue to pose a significant threat to public health and the environment