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McDowell& Davis Towing Quarterly Groundwater Sampling Report February 2002 Page: 2 Groundwater Elevations 02-01-02 Well Collar Elevation DTW GW Elevation MW-1 118.14 62.92 55.22 MW-2 118.79 62.56 56.23 MW-3 118.39 62.34 56.05 Groundwater flow was to the southwest (south 52 west) with a very shallow gradient (0.018 ft/ft). The potentiometric surface and groundwater flow direction are shown on Figure 2 Site Map 1 Groundwater Flow. Detectable concentrations of gasoline range petroleum hydrocarbons (0.08 mg/1) and benzene (1.1 ug/1) were present in well MW2 located adjacent to the former underground storage tanks and fuel dispensers. No other contaminants were reported for well MW2 or the other monitoring wells. All oxygenates were reported as not detected. The dissolved oxygen concentrations show a very slight variation (5.7 to 6.3) a slight decrease compared to past monitoring events which indicates continued biologic activity in the area of the soil contamination. The slight variations in the dissolved oxygen concentrations suggest that that the release has not caused a significant groundwater impact. Laboratory Groundwater Sample Results (11-20-2001 Sample I.D. I Gasoline Benzene Toluene E-Benzene Xylenes Oxygenates OZ MW-1 <0.05 <0.3 0.7 0.5 2.0 ND 5.8 MW-2 0.08 1.1 3.2 2.1 9.1 ND 5.7 MW-3 <0.05 <03 <0.3 <0.3 <0.6 ND 6.3 ND=Non Detect NA=Not Analyzed Mg/L for gasoline µg/L for BTEX,MTBE,and 8260 Oxygenated Compounds Gasoline and gasoline constituents were detected in very low concentrations in monitoring well MW-2 in the February 2002 monitoring event. Previous monitoring events have detected gasoline and gasoline constituents at concentrations that exceeded established water quality goals. Gasoline and gasoline constituents have been detected in soil samples collected at depths of 15 and 25 feet in the vicinity of the former dispenser island. Scheduled quarterly groundwater monitoring will continue. A study consisting of a receptor / well survey, contaminant mass calculation, and evaluation of active remediation is scheduled for this quarter (see Additional Activities). If potential receptors are not identified as at risk by the survey, corrective action should be limited to groundwater monitoring to verify plume stability and degradation prior to closure of the site.