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I <br /> CLEARWATER <br /> G R O U P I N C <br /> 1 <br /> 1.0 INTRODUCTION <br /> This report presents the results of second quarter 1995 field activities performed by <br /> Clearwater Group, Inc (Clearwater) at 1702 Jackson Street in Escalon, California <br /> (Figure 1) The tasks performed during this phase of work included groundwater <br /> gauging, groundwater sample collection, and vapor extraction system monitoring. <br /> 2.0 BACKGROUND <br />' The subject site is located in a mixed commercial and residential neighborhood of <br /> central Escalon, a small town lying in the southern Sacramento Valley of California <br /> The site was formerly a retail fuel facility; the service station building is the only <br />' structure that remains on site (Figure 2) The topography of the site and <br /> surrounding land is relatively flat. <br />' Results of a subsurface investigation conducted at the site indicates that the shallow <br /> subsurface consists predominantly of unconsolidated sand and silt In general, <br /> subsurface materials contain greater clay content below depths of 55 to 65 feet below <br /> ground surface (bgs) Depth to groundwater varies seasonally from approximately <br /> 67 to 69 feet bgs <br /> Results of analysis of soil samples collected during underground storage tank (UST) i <br /> removal indicated the presence of moderate to low concentrations of fuel <br /> hydrocarbons in soil at 10 5 to 115 feet bgs in the northeastern quadrant of the <br />' excavation. Details of UST removal, soil sampling and preliminary site evaluation <br /> have been presented by RESNA in reports entitled Preliminary Report, Assessment <br /> I of Soil Contamination (July 30, 1991) and Problem Assessment Report, Soil <br /> Contamination (December 23, 1991) <br /> A second phase of site characterization was implemented by RESNA following <br /> completion of the preliminary evaluation Four groundwater monitoring wells and <br /> several soil borings were drilled during this evaluation. As a result of this phase of <br /> I activity, the presence of fuel hydrocarbons was indicated in the vicinity of the <br /> former diesel tank, the lateral extent of hydrocarbons associated with the former <br /> gasoline tanks was estimated, and hydrocarbons were iindentified un soil beneath the <br /> former gasoline dispenser island. RESNA proposed and implemented a plan for the <br /> excavation of soil containing diesel components following completion of the <br /> comprehensive site characterization RESNA also recommended implementation <br /> of a vapor extraction program to address residual hydrocarbons beneath the former <br /> gasoline USTs. <br /> D-102 1Q95 1 August 31,1995 <br />