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J t <br /> l <br /> STATE OF CALIFORNIA <br /> PETE WILSON, Governor <br /> CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD— <br /> CENTRAL VALLEY REGION -_ <br /> 3443 ROUTIER ROAD, SUITE A <br /> SACRAMENTO, CA 95827-3098 .,. <br /> PHONE: (916) 361-5600rierr 4 <br /> FAX: (916) 361-5686 ? x, 3 12 April 1991 <br /> Ms. Eleanor Ratliff APR 17 1994,FNV6RONMENTA) hOLiIII <br /> San Joaquin County Public Health Services <br /> Environmental Health Division P E RMIT, ,S>FP,VIB <br /> P. 0. Box 2009 <br /> Stockton, CA 95202 <br /> REVIEW OF REQUEST FOR CLOSURE FOR ULTRAMAR - 35 NORTH CHEROKEE LANE - LODI, <br /> SAN JOAQUIN COUNTY <br /> Below are staff's comments on Ultramar's request for closure of the site at 35 <br /> North Cherokee Lane, Lodi. These comments should be incorporated with your <br /> correspondence. <br /> In reviewing past reports, it seems that the source of the gasoline contami- <br /> nation was never identified. Originally, the contamination found on site was <br /> diesel from a leaking diesel tank. As the investigation progressed, gasoline <br /> constitutes were found, but no leaks were identified with the underground <br /> gasoline tanks or the product lines. This should be clarified and a second <br /> unauthorized leak report submitted if necessary. <br /> Ultramar states, in their 11 February 1991 letter, that they operated a vapor <br /> extraction system at the site for 28 days in October 1989 and removed 1694.5 <br /> pounds of contaminants. Considering that a mass balance was never conducted, <br /> 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 <br /> analytical results of the wells show that all tested constitutes are below the <br /> detection limit of 0.5 ppb, but the ground water has dropped 12 feet over the <br /> last couple of years. The contaminants were probably left in the soils which <br /> are now above the ground water table. Some of the contaminants were removed <br /> by the vapor extraction system, but not all . <br /> We do not recommend that the site be closed at this time. It is likely that <br /> when the ground water table returns to its normal level , the contaminants will <br /> reenter the ground water. We suggest that the vapor extraction system be <br /> reinstalled and all contaminants be removed while the ground water table is <br /> low. If Ultramar is convinced that all the contamination is removed, then <br /> confirmation sampling of the soil must be performed to show all that the <br /> contaminated soil has been remediated for gasoline and diesel fractions. <br /> Monitoring well analyses are to continue on a quarterly basis. <br /> If you have any questions, please call me at (916) 361-5723. <br /> MES B. MAUGHAN <br /> Water Resource Control Engineer <br /> JBM:jbm <br />