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July 15, 1992 <br /> ARCO Station No 760, Lodi, California <br /> Between ,lune 18, and July 18, 1991, a geologist from RESNA observed removal of three <br /> gasoline-storage tanks and associated product piping, and two waste-oil tanks RESNA <br /> collected appropriate soil samples under each tank and the product lines according to the <br /> San Joaquin County Public Health Services,Environmental Health Division(SJCPHS-EHD) <br /> guidelines. In addition, a new tank cavity was excavated and soil samples were collected <br /> from the bottom and sidewalls of the new cavity <br /> In the vicinity of the waste oil tank formerly located east of the station building, residual <br /> gasoline and diesel fuel hydrocarbons remain in soil at a depth of 25 feet below surface <br /> grade (bsg) at concentrations that range from 3,600 to 5,500 parts per million (ppm) for <br /> gasoline and at a concentration of 4,300 for diesel fuel. <br /> In the former gasoline tank cavity, residual gasoline remains in the soil at approximately 13 <br /> feet bsg at maximum concentrations 250 (ppm) Borings B-4 through B-6 and B-9, drilled <br /> adjacent to the former tank cavity, did not reveal the presence of detectable gasoline <br /> hydrocarbons <br /> Hydrocarbons were detected in two soil samples collected at the north end of the product <br /> • dispensers at concentrations of 2,200 and 5,700 ppm Waste-oil was detected at 120 ppm <br /> in soil sampled under a waste-oil tank near the product lines Hydrocarbons were not <br /> detected in the remaining soil samples collected under and near the product dispensers <br /> Results of these investigations indicated that residual hydrocarbons in soil are not delineated <br /> laterally in the vicinity of the waste oil tank formerly located east of the station building, <br /> laterally to the north of the northern portion of the dispenser islands and vertically within <br /> the former tank cavity The results of these investigations are summarized in our Report <br /> No 38048-5, dated April 7, 1992 <br /> On this basis, RESNA proposes to drill additional borings and install additional vapor- <br /> extraction wells to further define residual hydrocarbons in soil and to provide additional <br /> remediation capability, as needed The idealized plan of a vapor-extraction well is shown <br /> on the Schematic Vapor-Extraction Well Design, Plate 3 Our proposed work is discussed <br /> below <br /> Proposed Work <br /> o Obtain City of Lodi authorization to drill two borings offsite north of the property <br /> _ boundary within a City nght-of-way <br /> • 3&98-7W 2 <br /> Working To Restore Nature <br />