SITE INFORMATION AND CORRESPONDENCE_CASE 1

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o NNW MEMORANDUM CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD • CENTRAL VALLEY REGION 3443 Routier Road. Suite A Phone: (916) 255-3000 Sacramento. CA 95827-3098 CAUM: 8-494-3000 TO: GLB, EAT FROM., Heidi Barr Underground Tanks Unit DATE. 16 January 1996 SIGNATURE. aa,�_ SUBJECT: REQUEST FOR CLOSURE, COCA COLA BOTTLING COMPANY, 1100 NORTH WILSON WAY, STOCKTON, SAN JOAQUIN COUNTY All of the necessary information and correspondence, according to Appends-B of the Tri Regional Recommendations, has been submitted. Ground water depth ranges from approximately 59.6 feet to 74.5 feet below ground surface (bgs), with a northeast flow direction. Contamination remaining in the soil consists of 0.010 parts per milrion (ppm) ethyl benzene and 0.16 ppm xylenes, at 21 feet bgs. Presently this site is unoccupied. In April 1990, one 1,000 gallon gasoline tank and one 10,000 gallon diesel tank were removed, along with the associated piping and fuel dispensers. Four samples were taken and detected up to 180 ppm total petroleum hydrocarbons as diesel (TPHd), up to 3600 ppm TPH as gasoline (TPHg), and benzene, toluene, ethyl benzene, and xylenes (BTDq ranged from 6.6 ppm to 200 ppm. In May 1990, a soil gas survey was conducted. Twenty eight soil probes detected TPHg from non-detect(ND) to 90 ppm. In August and September 1990, a total of thirteen soil borings(B-1 through B-13) were drilled to depths of 70 to 95 feet bgs. Fifty two soil samples were collected and showed up to 8900 ppm TPHg, up to 20,000 ppm TPHd, and BTEC was highest in xylenes at 920 ppm. The most concentrated depth of contamination was at 20 feet bgs. Eleven additional soil borings(B-14 through B-24) were drilled in October and November 1990. Preparation for in-situ remediation began in October 1990. Wells VEW-1 through VEW-4 were installed and VEW-5 through VEW-8 were installed in November 1991. In November 1992, RESNA conducted a soil vapor extraction test on the eight existing wells. TPHg ranged from 33 milligrams per cubic meter to 19,000 milligrams per cubic meter. RESNA installed a vapor extraction system in June and July 1993 and operated until it was shut down in April 1995 due to electrical problems. SMITH Environmental drilled seven confirmation borings (CB-1 through CB-7) in September and October 1995 to depths of 46.5 to 75 feet bgs. Contamination of 0.010 ppm ethyl benzene and 0.16 ppm xylenes were detected in CB-2 only, at 21.5 feet bgs.