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petroleum hydrocarbons by EPA Methods 8015 and 418.1, triethylene glycol by EPA Method 8015, and benzene, toluene, ethylbenzene and xylenes by EPA Method 8020. In addition, one soil sample was analyzed for volatile organic compounds (VOCs) by EPA Method 8240, polychlorinated biphenyls (PCBs) by EPA Method 8080, and semivolatile compounds by EPA Method 8270 EPA Method 8015. The chemical analytical results of these soil samples indicate that petroleum hydrocarbon compounds are present in the shallow soils adjacent to the discharge line (Table 2). Triethylene glycol was reported in one sample at a concentration of 12,000 mg/kg. The results of the analyses for the other compounds indicate very low to non-detectable concentrations of benzene, toluene, and xylenes, and non-detectable concentrations of PCB's and semivolatile compounds. SITE DESCRIPTION The Lathrop Gas Dehydrator Station is located at the intersection of Willow Glen and Undine Roads, near French Camp in San Joaquin County (Figure 1). The station is owned by PG&E and occupies an area of approximately one-third acre which is flat and covered with gravel fill. This facility is unmanned and has been used for odorizing and removing production fluids in the natural gas since the 1960's. The reboiler unit, however, has not been operated since 1989. The Lathrop Gas Dehydrator Station lies at an elevation of approximately 5 feet above sea level in the San Joaquin delta. The Middle River, located approximately 1,000 feet to the west of the site, is the nearest surface water body (Figure 1). REGIONAL GEOLOGIC AND HYDROGEOLOGIC SETTING The Lathrop Gas Dehydrator Station is located within the northwestern part of the San Joaquin Valley between the San Joaquin River and the Coast Range Geomorphic Province. The San Joaquin Valley is a topographic and structural basin bounded on the east by the Sierra Nevada Range and the west by the Coast Ranges. The dehydrator station is situated on a veneer of recent fluvial deposits that consist mainly of clay and silty fine-grained sand to a depth of about 13 to 14 feet (Groundwater Technology, Inc., 1988). This facility is also located in the San Joaquin Groundwater Basin. Locally, recharge to the basin occurs to the west of the site in the foothills of the Diablo Mountain Range, and from surface infiltration. Discharge from the basin occurs through drainage into the San Joaquin River and its tributaries (e.g., Old River to the south and Middle River to the west of the site), and by groundwater withdrawl from domestic and production wells. Based on the site investigation performed by Groundwater Technology, Inc., the depth to first groundwater at the site is approximately 12 feet below grade. cca/9-3o-92/8913a/JAWP13 5