SITE INFORMATION AND CORRESPONDENCE

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HORIZON ENVIRONMENTAL INC. � Specialists in Site Assessment,Remedial Testing,Design and�Operaflon 2: C2 June 17, 1998 Mr. Jim Munch State Water Resources Control Board Division of Clean Water Programs UST Cleanup Fund P.O. Box 944212 Sacramento, California 95244 - 2120 Subject: Request for Expedited Case Closure Review Former Discovery Chevrolet Site ID Code: 2595 1615 11th Street, Tracy, California. Mr. Munch: At the request of our client, Ms. Michelle Nokes, Horizon Environmental Inc. (Horizon) has prepared this summary letter discussing the rationale for an Expedited Case Closure Review at the above-referenced site. The purpose of this letter is to provide information on investigative and corrective actions performed to date on the site, and justification for this request to the State Water Resources Control Board (SWRCB). On behalf of Ms. Nokes, Horizon is appealing the denial of case closure for the site by the local enforcement agency, the San Joaquin County Public Health Services Environmental Health Division (SJC PHS/EHD). The subject site is a former automobile dealership located at 1615 11th Street in Tracy; California as shown on the Site Vicinity Map (Figure 1). The site is owned by Thomas Nokes, was formerly occupied by Discovery Chevrolet, and most recently by Tracy Chevrolet. Currently the site is unoccupied. Site facilities include an auto showroom, a sales office, and service bays. Locations of these facilities and other pertinent site features are shown on the Site Plan (Figure 2). In April 1993, two 500-gallon gasoline USTs were removed from a common excavation, and one waste-oil UST was also removed from the site. When the two gasoline USTs were removed, four soil samples were collected from the base of the excavation at a depth of approximately 9 to 10 feet below surface grade (bsg). These soil samples were found to contain total petroleum hydrocarbons as gasoline (TPHg) at concentrations ranging from 920 to 4,400 parts per million (ppm). Groundwater was not encountered in the gasoline tank excavation. A soil sample collected from the base of the waste-oil UST cavity at 7.6 feet bsg indicated 31 ppm TPHg, 270 ppm total petroleum hydrocarbons as diesel (TPHd), and 0.18 ppm benzene. In addition, a sample was collected at 5.6 feet below the dispenser located inside the building. Benzene was detected at 0.88 ppm in the sample collected from beneath the dispenser. After removal of the USTs, the gasoline UST excavation was backfilled with the excavated soil from the cavity and imported pea gravel. 5011 Golden Foothill Parkway,Suite 7 • EI Dorado Hills,CA 95762 • (916)939-2170 • FAX(916)939-2172 PO.Box 5283 • Bakersfield,CA 93388 • (805)589-8389 • FAX(805)589-1456