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PUBLIC HEALTH SERVICES <br /> SAN JOAQUIN COUNTY == y <br /> JOGI KHANNA M.D.,M.P.H. <br /> Health Officer <br /> P.O.Box 2009 • (1601 East Hazelton Avenue) •Stockton, California 95201 c°�JFOR��P <br /> MAYO 3 1991 (209)468-3400 <br /> GLENN DEMBROFF <br /> �. <br /> ULTRAMAR INC <br /> P O BOX 466 <br /> HANFORD CA 93232-0466 <br /> RE: Beacon Station No. 502 IN REPLY REFER TO SITE CODE: 1320 <br /> 35 N. Cherokee Lane, Lodi, CA <br /> Please be advised that San Joaquin County Public Health Services, Environmental Health Division <br /> (PHS/EHD) and Central Valley Regional Water Quality Control Board (CVRWQCB) staff have reviewed <br /> recently and previously submitted technical documents related to the contamination remediation at the <br /> above referenced site. <br /> In reviewing past reports, it seems that the source of the gasoline contamination was never identified. <br /> Originally, the contamination found on site was diesel from a leaking diesel tank. As the investigation <br /> progressed, gasoline constituents were found, but no leaks were identified with the underground gasoline <br /> tanks or the product lines. This should be clarified and a second unauthorized leak report submitted if <br /> necessary. <br /> Ultramar states, in their February 11, 1991 letter, that they operated a vapor extraction system at the site <br /> for 28 days in October 1989 and removed 1694.5 pounds of contaminants. Considering that a mass balance <br /> was never conducted, we do not understand why the vapor extraction system was abandoned when <br /> contaminants were still being removed from the soil by the system. The analytical results of the wells show <br /> that all tested constituents are below the detection limit of 0.5 parts per billion (ppb), but the groundwater <br /> has dropped 12 feet over the last couple of years. The contaminants were probably left in the soils which <br /> are now above the groundwater table. Some of the contaminants were removed by the vapor extraction <br /> system, but not all. <br /> We do not recommend that the site be closed at this time. It is likely that when the groundwater table <br /> returns to its normal level, the contaminants will re-enter the groundwater. We suggest that the vapor <br /> extraction system be reinstalled and all contaminants be removed while the groundwater table is low. If <br /> Ultramar is convinced that all the contamination is removed, then confirmation sampling of the soil must <br /> be performed to show all that the contaminated soil has been remediated for gasoline and diesel fractions. <br /> Monitoring well analyses are to continue on a quarterly basis. Please submit a work plan to continue <br /> remediation by June 3, 1991. <br /> If you have and questions, contact Eleanor Ratliff, REHS, at (209)468-3454. <br /> Jogi Khanna, , M.P.H. <br /> Health OM <br /> a ie A. Cotulla, REHS, Program Manager <br /> nvironmental Health Division <br /> LAC/ER:nr <br /> c: CVRWQCB <br /> A Division of San Joaquin County Health Care Services �� <br />