SITE INFORMATION AND CORRESPONDENCE

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MEM0RANDUh -o-, CAUFORNIA REGIONAL WATER QUALITY CONTROL BOARD • CENTRAL VALLEY REGION 3443 Routier Road, Suite A Phone: (916)255-3000 Sacrarrjento, Califomia 95827-3098 CALNET: 8-494-3000 TO: B,EAr FROM: Heidi Barr erground Tank Unit DA 27 July 1995 SIGNATURE: 4� sUBJEC'T: REQUEST FOR CLOSURE FOR LINDEN UNIFIED SCHOOL DISTRICT BUS GARAGE, 18351 EAST MAIN STREET, LINDEN, SAN JOAQUIN COUNTY San Joaquin County Public Health Services (County) closed the site in October 1994. A complete closure report was not submitted, and the Appendix B checklist could not be completed. However,we received a Local Oversite Program (LOP) closure checklist completed by the County. Our file for the site contains only an unauthorized release form (URF), the County notification of hazardous waste discharge,the County notice of reimbursement and the County closure letter and checklist. We have no other correspondence for the site. Three slant borings were drilled in December 1989, after a failed tank test and soil analyses indicated contamination. The concentrations of contamination were not provided. Two 10,000 gallon diesel fuel tanks,one 2,000 gallon gasoline tank and approximately 500 cubic yards of contaminated soil was removed from the site. The exact date of the excavation is unknown. The URF was filed in March 1990, and the County wrote a notification of hazardous waste discharge in May 1990. The County closure checklist states that 500 cubic yards of excavated soil was aerated on- site. Up to 0.009 parts per million (ppm)benzene and 0.021 ppm toluene remain in place. The estimated amount of contamination remaining is 0.069 pounds of benzene and 0.161 pounds of toluene. The estimated depth to ground water is 105 to 110 feet below ground surface. HB Based on the low concentrations and low volume of contamination remaining and the completion of the LOP closure checklist,staff concurs with no further action. r sDJ��