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Feasibility Study/Corrective Action Plan 2 <br /> The Drake Property 26485 Thornton Road Thornton California November 26 1996 <br /> During June 1993 UST removal activities, Wallace-Kuhl collected soil and groundwater samples from the <br /> southern UST pit Benzene concentrations were non-detect in any soil and groundwater samples analyzed <br /> during this Investigation (Wallace-Kuhl, 1993) <br /> On November 19, 1993, Waliace-Kuhl conducted an additional Investigation to further assess the extent of <br /> petroleum hydrocarbon Impact upon site soils and groundwater Over-excavation of the southern UST pit <br /> removed approximately 150 cubic yards of hydrocarbon-impacted soil from beneath the former UST pit and <br /> dispenser island Exploratory trenches were dug to estimate the lateral extent of hydrocarbon-impacted <br /> soil In addition, groundwater monitoring wells MW-1, MW-2 and MW-3 were Installed and sampled <br /> Benzene was non-detect in any soil and groundwater samples analyzed In this investigation (Wallace-Kuhl, <br /> 1994) <br /> Based on the results of the November 1993 investigation, the extent of hydrocarbon-impacted soil was <br /> estimated to encompass a 120-square-foot area between the former USTs and eastern pump island <br /> (Wallace-Kuhl, 1994) <br /> Wellhead elevations, obtained during a professional well survey conducted on January 31, 1995,were <br />• combined with groundwater monitoring data collected during previous quarters by Wallace-Kuhl to <br /> determine the groundwater flow direction beneath the site Based upon the results of the background <br /> review and determination of groundwater flow direction, Groundwater Technology, Inc (Groundwater <br /> Technology) advanced and sampled soil borings B-1 through B-10 on February 17, 1995 (Figure 2) <br /> Groundwater samples were collected from temporary wells Installed in the borings The objective of soil <br /> and groundwater sampling was to further define the extent of hydrocarbon-impacted soil and groundwater <br /> identified during the installation of MW-1, MW-2 and MW-3 (Groundwater Technology, 1995) <br /> 22 Site Conditions <br /> The site is located approximately 8-9 feet above mean sea level and the site topography is flat The site is <br /> bordered to the east by Thornton Road and an open field, to the south by Walnut Grove Road and a large <br /> truck stop (BP fueling facility),to the north by residential property, and to the west by Interstate 5 A <br /> drainage ditch (approximately 3-4 feet deep) runs east/west on the south side of Walnut Grove Road <br /> 23 Results of Soil Assessment <br /> Table 1 summarizes analytical results of soil samples collected on site Soil samples collected at depths of <br /> 4 to 9 feet below ground surface (BGS) from the UST excavation In June 1993 by Wallace-Kuhl contained <br /> is <br /> no detectable benzene concentrations and a maximum total petroleum hydrocarbons-as-gasoline (TPH-G) <br /> 0191FEA RPT(Misc 15) <br /> FLUOR DANIEL GTI <br />