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i s} Chemical Analytical Methods and Results Nine groundwater samples were analyzed using EPA Methods 503018015, 602 and 8260 for Total Petroleum Hydrocarbons as Gasoline (TPHG), Benzene, Toluene, Ethylbenzene and Xylene (BTEX) and fuel oxygenates including Methyl-tert-butyl-ether (MTBE), Tert-Butyl Alcohol (TBA), Di-Isopropyl Ether (DIPE), Ethyl tent-butyl ether (ETBE), Tert-Amyl Methyl Ether TAME), 1,2-Dichloroethane (1,2-DCA) and Ethylene Dibromide (EDB) The analytical results of the groundwater samples for this sampling event are attached and listed below in Table 1(histonc data is presented In Table 2), Table 1. Current Quarter Groundwater Chemical Data —Sample TPHG Ben Tol Ethyl Xyl MTBE TBA DIPE ETBE TAME u uqA uciA uqA u UCIA ugA u /I u-qA UgA MW-1 ND NO ND ND NO NO NO ND ND NO MW-2 2200 68 NO 63 33 ND ND ND ND NO MW_3 1500 29 22 71 140 ND ND ND ND NO MW-4 NO NO ND ND NO ND ND ND ND NO MWS NO ND NO ND ND ND ND NO ND NO MW-6 890 25 69 46 92 ND ND NO ND NO MW-7 NO NO NO NO ND ND ND NO ND ND MW_8 NO NO NO ND ND NO ND NO ND ND MW-9 140D 860 74 790 1900 ND ND ND ND NO . Blank NO NO ND NO ND ND ND NO ND ND N D-None detected u9A-micrograms per liter Ben-Benzene Toi-Toluene Xyl-Xylene Fuel Ox -Fuel Oxygenates by Method 6260 from Dee, 1997 forward Ethyl-Ethylbenzene 1,2 Dichioroethane and Ethylene Dibromide NO in all wells Discussion Groundwater flow direction is north-northeasterly at a low flow gradient which is consistent with historically observed trends Contaminants were observed in the Wells MW-2, MW-3, MW-6 and MW-9 Contaminants were not observed in MW-1 and MW-4 Benzene concentrations declined in Wells MW-2 and MW-3 The groundwater mound" previously centered at well MW-2 has disappeared, groundwater mounds have formed in this vicinity in the past This episodic occurrence of these "mounds" suggests seasonal groundwater recharge, surface leakage or subsurface pipe leakage as possible causes The mounds do not appear to affect overall groundwater flow direction Concentrations continue to vary which indicates that desorbtion Influences the concentration levels observed depending upon fluctuating aquifer water levels and the contaminant absorbtlon to soil (see discussions In previous reports) These concentration variation trends are attributed to fluctuations in water levels and contaminant desorbtion from the aquifer sediment/soil in the Immediate vicinity of the wells, and they are expected to continue i n r