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1 A <br /> McDowell& Davis Towing <br /> Quarterly Groundwater Sampling Report May 2002 <br /> Page: 2 <br /> Groundwater Elevations 05-03-02 <br /> Well JCollar Eleva—t7on—T DTW GW Elevation <br /> MW-1 118.14 62.67 55.47 <br /> MW-2 118.79 62.31 56.48 <br /> MW-3 118.39 62.07 56.32 <br /> Groundwater flow was to the northeast (north 23 east) with a very shallow gradient <br /> (0.016 ft/ft). The potentiometric surface and groundwater flow direction are shown on <br /> Figure 2 Site Map / Groundwater Flow. Detectable concentrations of toluene (0.6 ugh) <br /> and xylenes (1.1 ug/l), below water quality goals, were present in well MW2 located <br /> adjacent to the former underground storage tanks and fuel dispensers. No other <br /> contaminants were reported for well MW2 or the other monitoring wells. All oxygenates <br /> were reported as not detected. <br /> The dissolved oxygen concentrations show a very slight variation (6.5 to 7.1) a slight <br /> increase compared to past monitoring events which indicates continued biologic activity <br /> in the area of the soil contamination. The slight variations in the dissolved oxygen <br /> concentrations suggest that that the release has not caused a significant groundwater <br /> impact. <br /> Laboratory Groundwater Sample Results 05-03-2002 <br /> Sample I.D. I Gasoline I Benzene I Toluene7E-Benzene X lenes I Oxygenates Oz <br /> MW-1 <0.05 1 <0.3 10.3 1 <0.3 <0.6 1 ND 1 7.1 <br /> MW-2 <0.05 1 <0.3 10.6 <0.3 1.1 ND 1 6.5 <br /> MW-3 <0.05 1 <0.3 1 <0.3 <03 <0.6 ND 6.7 <br /> ND=Non Detect NA=Not Analyzed <br /> Mg/L for gasoline µg/L for BTEX,MTBE,and 8260 Oxygenated Compounds <br /> Volatile aromatic hydrocarbons were detected in very low concentrations, below water <br /> quality goals, in monitoring well MW-2 in the May 2002 monitoring event. Previous <br /> monitoring events have detected gasoline and gasoline constituents at concentrations that <br /> exceeded established water quality goals. Gasoline and gasoline constituents have been <br /> detected in soil samples collected at depths of 15 and 25 feet in the vicinity of the former <br /> dispenser island. Scheduled quarterly groundwater monitoring will continue. <br /> A study consisting of a receptor / well survey, contaminant mass calculation, and <br /> evaluation of active remediation has been submitted under separate cover. If potential <br /> receptors are not identified as at risk by the survey, corrective action should be limited to <br /> groundwater monitoring to verify plume stability and degradation prior to closure of the <br /> site. <br />