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McDowell & Davis Towing <br /> 1360 Escalon Avenue, Escalon, California <br /> Phase II <br /> Groundwater Monitoring Well Installation <br /> Report <br /> 1.0 PROJECT IDENTIFICATION <br /> The objective of this phase was to provide a scope of work that would further define the <br /> lateral and vertical extent of the hydrocarbon plume in the soil and groundwater at the <br /> McDowell & Davis Towing facility. The work included the definition of the <br /> groundwater flow direction. Three on-site groundwater-monitoring wells were installed, <br /> in various locations, to obtain soil and ground water samples and for the calculation of <br /> the groundwater gradient. <br /> 1.1 Site Description and History <br /> r3' <br /> Four underground fuel tanks were removed on March 15, 1999 by SEMCO under <br /> permit. Hydrocarbon odors were noted in the soil beneath the west end of the <br /> dispenser island area. Soil samples for analysis were collected as required from <br /> beneath the tanks, the dispenser islands, the piping lines, and from the soil <br /> stockpiles. Analytical results disclosed up to 210 ppb of MTBE, 2,700 ppb TBA <br /> and 570 ppb xylenes from the former tank pit, and 5,000 ppb TBA and 110 ppb <br /> xylenes from the former dispenser island area. <br /> On January 28, 2000 M. J. Kloberdanz & Associates drilled 4 soil borings in the <br /> vicinity of the former underground tanks and fuel island using a rig equipped with <br /> a hollow stem auger, sampling spoon, and brass sleeves to collect soil samples for <br /> laboratory analyses. <br /> Boring B-1 was drilled next to the former tank excavation where levels of <br /> contamination were disclosed during the tank removal. The boring was drilled to <br /> 40 feet in depth with no odor or soil discoloration encountered. Laboratory <br /> samples were obtained from various depths including the bottom of this boring. <br /> All samples were reported as "non-detect for the compounds analyzed" by the <br /> analytical laboratory. <br /> Boring B-2 was drilled in the fuel island area, PL# 7, where soil contamination <br /> was disclosed during the tank removal. Petroleum contamination was apparent in <br /> the soil to a depth of about 20 feet. This boring was drilled to 45 feet in depth in <br /> order to terminate in a silt or clay soil. Sandy soils were encountered between 20 <br /> and 40 feet in depth. Apparent contamination and laboratory soil samples were <br /> non-detect below the 25-foot sample. <br />