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1 1 <br />. Groundwater samples collected from monitoring well MW-3 contained <br /> 130 ppb MTBE Groundwater samples collected from monitoring wells <br /> MW-13 and MW-14 contained 1,900 ppb MTBE and 180 ppb MTBE, <br /> respectively Both of these wells are downgradxent of the site MTBE <br /> exceeded the DHS MCL for drinking water in monitoring wells MW-3, <br /> MW-13, and MW-14 Low concentrations of MTBE, below DHS MCLS for <br /> drinking water, were detected In monitoring wells MW-1, MW-2, MW-4, <br /> MW-8, and MW-9 <br /> Elevated TBA concentrations were detected in groundwater samples <br /> collected from monitoring wells MW-3, MW-13, and MW-14 There was <br /> an increase in TBA from previous results <br /> There was a dramatic decrease in ethanol concentrations in groundwater <br /> samples collected from monitoring well MW-12 since last quarter where <br /> the ethanol concentrations dropped from 58,000 ppb last quarter to 14 <br /> ppb this quarter <br /> Relatively low concentrations of PCE, 1 ,2-dichloropropane, and ETBE were <br /> detected in groundwater samples collected from the site None of these <br />. concentrations exceeded DHS MCLs for drinking water <br /> Groundwater in the shallow zone (less than 20-feet bgs) appeared to flow <br /> to the north beneath the site at a gradient of approximately 0 0016- <br /> feet/foot This groundwater flow direction is generally consistent with <br /> previous findings Groundwater in the middle zone (55-70-feet bgs) <br /> appeared to flow to the south, toward the on-site drinking water well, <br /> with a gradient of approximately 0 0143-feet/foot This groundwater flow <br /> direction in the middle zone is different from last quarter which showed <br /> the groundwater flow to the east <br /> There seems to be a notable decrease in hydrocarbon concentrations with <br /> depth in the well cluster between the USTs and the garage (MW-6, MW-7, <br /> and MW-8) Since there are still high concentrations of hydrocarbons in <br /> the furthest downgradient wells (MW-13, MW-14, and MW-15), the extent <br /> of contamination is undefined in that direction <br /> 6.0 RECOMMENDATIONS <br /> Additional assessment and sampling is outlined in ASE's workplan dated <br /> June 16, 2000 The preparation for the sampling of the area drinking <br /> water wells is currently underway ASE anticipates that the work outlined <br /> in the workplan will be conducted throughout the next quarter <br /> Frank's One Stop Quarterly Report — June 2000 Sampling <br /> -4- <br />