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EXECUTIVE SUMMARY <br /> Six borings were drilled during the fourth quarter of 2003 using cone penetrometer testing (CPT) <br /> equipment, and groundwater samples were collected for laboratory analysis Quarterly groundwater <br /> monitoring was conducted concurrent with the drilling, and all results are reported here <br /> The borings ranged in depth from 100 to 130 feet, and three separate water-bearing sand bodies <br /> within the middle Pleistocene Riverbank Formation were identified and sampled These sand <br /> bodies appear to be fluvial channel deposits that are oriented in an east-west direction They aie 10- <br /> 15 feet thick in the central part of the site, but thin and die out to the north and south <br /> Fourteen water samples were collected from the borings, and diesel was detected in six of these <br /> Diesel was also detected in two of the monitor wells, where it had previously been detected on <br /> several occasions Diesel and gasoline were detected in all three samples from the deepest boring, <br /> which was located near the former UST cavity The extent of diesel in the uppermost Riverbank <br /> channel (above 70 feet) was mapped and its distribution was compared to a facies and isopach map <br /> of the channel The plume occupies an estimated area of slightly over 5,000 square feet within this <br /> channel <br /> Low to moderate diesel concentrations were detected in deeper channel deposits (below 80 feet) in <br /> one CPT boring near the former UST cavity, but not in other boiings or any of the monitor wells <br /> These deeper deposits might be slightly impacted in the immediate vicinity of the UST cavity <br /> The water elevation data were contoured to yield a map of the piezometric surface The elevation <br /> contours again form an are in the southern part of the site area, and the water table appears to be <br /> tilted to the south <br /> 1 <br />