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<br /> CALIFORNIA REG NAL ,TER QUALITY CONTROL BOARD-.00:ENTRAL VALLEY REGION
<br /> 3443 Rower Road,S its
<br /> Phone: (916)255-3000
<br /> Sacramento,CA 958 7-3 98 CALNET:8-494-3000
<br /> To: , G From: WEG
<br /> Undergr nd Tank Unit
<br /> DATE: 26 Oct ber 1995 SIGNATURE:
<br /> Subject: REQ EST FOR CLOSURE, LODI READYMIXAND BUILDING MATERIALS, 851
<br /> EAST LODI AVENUE, LODI, SANJOA QUIN COUNTY
<br /> In May 1995, Geological Technics, Inc., submitted a closure report which contained all the information
<br /> requested for closure in Appendix B to the Tri-Regional Recommendations. Remedial activities at the
<br /> site began in November 1990, and were completed in July 1993. After over-excavation, soil
<br /> contamination remains at the site.
<br /> In December 1989, two 1,000 gallon underground storage tanks (UST's), one formerly containing
<br /> gasoline and the other diesel, were removed from the site. Five soil samples were taken during the
<br /> excavation at 9.5 feet below ground surface (bgs). These samples were tested for total petroleum
<br /> hydrocarbons as gasoline(TPH-g), as diesel(TPH-d), and benzene, toluene, ethylbenzene, and xylenes
<br /> (BTEX). The concentrations ranged from non-detect (ND) to:
<br /> • 3,000 parts per million(ppm) TPH-g,
<br /> • 50,000 parts per billion (ppb) benzene,
<br /> • 270,000 ppb toluene, and
<br /> • 420,000 ppb xylenes
<br /> In August 1990, over-excavation of the former UST location was performed and soil samples were tested
<br /> for TPH-g, TPH-d, and BTEX. Based on the results, a second excavation was performed in October
<br /> 1990. During this excavation, six soil samples tested for the same constituents. All samples tested ND
<br /> except for the following:
<br /> • 150 ppm TPH-d, 27 ppm TPH-g, 600 ppb toluene, 3800 ppb ethylbenzene, and 14,000 ppb
<br /> xylenes at 25 feet bgs on the pit bottom,
<br /> • 3.4 ppm TPH-d at 16 feet bgs along the sidewall,
<br /> • 13 ppm TPH-d at 18 feet bgs along the side wall,
<br /> • 89 ppm TPH-d at 23 feet bgs on the pit bottom, and
<br /> • no benzene was detected.
<br /> The series of two excavations removed approximately 500 cubic yards of contaminated soil. This soil
<br /> was then treated and spread on-site.
<br /> In July 1993, a single soil boring was drilled on the south edge of the excavation to delineate the vertical
<br /> extent of the contamination. The boring was drilled to 42 feet bgs and soil samples were taken at 22, 32,
<br /> 37, and 42 feet bgs. All samples tested ND for TPH-g, TPH-d, and BTEX. Based on the soil
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