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PUBLIC HEALTH SERVrCES <br /> SAN JOAQ.UIN COUNTY <br /> ENVIRONMENTAL HEALTH DMSION ` <br /> Karen Furst, M.D., M.P.H., Health Officer c .. <br /> 304 East Weber Avenue, Third Floor• Stockton, CA 95202 <br /> 209/468-3420 <br /> JERRY MOO <br /> RE FILE CIO <br /> MOORE PETROLEUM FEB 01 1999 <br /> P O BOX 67 <br /> BANTA CA 95340 <br /> RE: Moore Petroleum SITE CODE: 1502 <br /> 5491 "F" Street <br /> Banta, CA <br /> San Joaquin County Public Health Services, Environmental Health Division <br /> (PHS/EHD) has reviewed the "Tank Closure Results & Recommendations <br /> Report" dated December 24, 1998 and the "Fourth Quarter 1998 Groundwater <br /> Monitoring Report" dated January 14, 1999, prepared by Apex Envirotech, Inc. <br /> for the above referenced site. <br /> The analytical results of the soil samples obtained below underground storage <br /> tanks (UST) 1 through 7 at 12 feet below surface grade (bsg), UST 9 at 9 feet <br /> bsg, and the bulk loading rack at 9 feet bsg verified soil contamination. In the <br /> previous site investigations, the soil samples below 10 feet were not analyzed. <br /> The vertical extent of soil contamination has not been defined. The December <br /> 24, 1998, report recommends geoprobe sampling of soil to 15 feet bsg. Soil <br /> samples should be collected until two consecutive 5 feet samples appear from <br /> field observations to not be contaminated. These soil samples should be <br /> analyzed to confirm that the soil contamination has been delineated vertically <br /> and laterally. Sufficient contaminated soil samples should be analyzed in order <br /> to calculate the mass of contamination remaining in place. <br /> The analytical results of the grab groundwater samples obtained from the <br /> excavations also verified contamination. One of the water samples evidenced <br /> methyl tertiary butyl ether (MTBE) at 11000 ug/L. The existing monitoring wells <br /> are screened to a depth of 20 to 26 feet. If soil contamination exists below these <br /> depths, the groundwater below these depths must be investigated (sampled and <br /> analyzed), in order to define the groundwater contamination laterally and <br /> vertically. In addition to the contaminants and methods proposed in the <br /> December 24, 1998 report, the groundwater samples should be analyzed for the <br /> five oxygenates previously analyzed for, using EPA Method 8260. <br /> A Division of San Joaquin County Health Care Services <br />