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1 On May 17, 1996, IT Corporation sampled the groundwater from the three monitoring wells This was the first recorded groundwater analytical data from these wells Groundwater samples ' from each of the wells contained concentrations of gasoline hydrocarbons including benzene The highest concentrations of TPH-gasoline (770 micrograms per liter (,ug/L)) and benzene (2 2 ' 4g/L) were detected in MW-3 Groundwater from the three wells was sampled again on September 27, 1996 The analytical results from this sampling event indicated that two of the ' three wells (MW-1 and MW-3) did not contain detectable concentrations of gasoline hydrocarbons The groundwater sampled collected from MW-2 did contain 430 Acg/L of TPH- ' gasoline and 3 7 µg/L of benzene During the fourth quarter of 1996, groundwater was sampled on December 13, 1996 The results from this sampling event indicated that gasoline ' hydrocarbons were present in only one of the three wells sampled The groundwater sample collected from MW-2 contained 250 4g/]L of TPH-gasoline 3.0 Groundwater Monitoring ' On March 12, 1997, groundwater from the three on-site wells was monitored and sampled A monitoring well construction summary for all of the wells installed at the site is presented in Table 1 and the well locations are illustrated in Figure 2 (Site Plan) Depth to groundwater measurements were taken in all three monitoring wells to evaluate groundwater flow and gradient characteristics The depth to groundwater at the site ranged from 31 75 to 32 51 feet ' bgs As such, the groundwater surface is above the screened interval of the three on-site wells ' Groundwater elevations beneath the site ranged from a high of 66 76 feet in MW-1 to a low of 66 62 feet in MW-3 Wellheads were previously surveyed relative to an arbitrary datum of ' 100 feet On average, groundwater levels have risen approximately 3 84 feet since the last monitoring event in December 1996 Groundwater flow was determined to be in an easterly direction at a gradient of 0 003 foot/foot The groundwater flow direction is not consistent with the last monitoring event and the gradient decreased 0 067 foot/foot A groundwater surface ' contour map is included as Figure 3 IT collected dissolved oxygen readings from each monitoring well Dissolved oxygen concentrations ranged from 0 91 ppm in MW-1 to 0 12 ppm in MW-2 and MW-3 A summary of groundwater monitoring data is provided in Table 2 2