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Subsurface Investigation, Well Installation, and Sample Analyses Results Page 5 <br /> Cintra Park Phase II Development, <br /> Tract 2705, Tracy, California <br /> July 23, 1998 CTE Job No. 20-0445B <br /> ethylbenzene, and total xylenes (BTEX), and lead. Detected TPH-G concentrations were 8,100 <br /> and 8,200 mg/kg. TPH-D and benzene were not detected at the laboratory detection limits used. <br /> Toluene concentrations were 380,000 and 110,000 g/kg, ethylbenzene concentrations were <br /> �— 140,000 and 230,000 µg/kg, and total xylenes concentrations were 790,000 and 1,200,000 µg/kg. <br /> Lead concentrations of 10 and 14 mg/kg were also detected. <br /> k . <br /> 3.2 Previous Site Assessment and Remedial Excavation Activities <br /> A San Joaquin County, Public Health Services, Environmental Health Division (PHS/EHD) <br /> approved work plan dated June 17, 1997 guided the site assessment and remedial excavation <br /> a activities performed in July 1997. Activities performed by CTE included the excavation and <br /> removal of greater than 800 cubic yards of hydrocarbon- and non-hydrocarbon-affected soil from <br /> �rt <br /> the area of the former UST cavities (CTE, 1997). Excavations, to a maximum depth of <br /> approximately 11 fbg, were performed using typi,at heavy-duty construction equipment. <br /> Conclusions reached as a result of this investigation are listed below: <br /> • A release of fuel hydrocarbons (gasoline) occurred from the former USTs onsite. This <br /> release apparently penetrated the soil column to a depth of approximately eight to 10 fbg. <br /> Where readily observed it appeared that an inverted cone of hydrocarbon-affected soil had <br /> formed beneath the tank cavity area. Hydrocarbon-affected soil also appeared to have spread <br /> It. laterally via the septic system trench (which traversed the excavation area) and along the <br /> capillary fringe soil zone above the groundwater table. Based on visual observations, where <br /> lateral spreading had occurred via the capillary fringe the zone of affected soil was <br /> approximately one to two feet thick. <br /> I . <br /> C:1TEEL FILESICINTRA PAiW,%CINTRA7-13.000 <br /> 6+ <br />