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LEVINE-FRICKE The need for remediation of soils containing less than 1,000 ppm of petroleum hydrocarbons is generally evaluated by the RWQCB based on site conditions and potential impacts to ground water or surface water. The potential impacts of this release on ground or surface water appear to be relatively low. The low -permeability clays underlying the Site should aid in retarding migration of the gasoline both vertically and horizontally. Additionally, ground -water depth in the general site vicinity is reported to be about 40 feet below the ground surface (as discussed with Ms. Kasey Foley during tank removal activities) so that potential impacts to ground water are �- probably low, based on depth, limited migration potential, and natural attenuation factors. The nearest surface water is a drainage channel, located along the northern property boundary, about 300 feet from the dispenser area. In the absence of observable free -phase petroleum saturation, it is unlikely that the gasoline will migrate horizontally in shallow soils over this distance. Although EDB was detected in these samples, its presence is believed to be unrelated to the reported past storage of leaded gasoline. The absence of gasoline in most site soils in the vicinity of the former tank and piping indicates that significant fuel leakage has not occurred; therefore a fuel source for the EDB has not been identified. Additionally, EDB has been a widely _a used chemical in rural areas for the purposes of crop fumigation. It is likely that EDB may be widespread in soils in the site vicinity, which may reflect agricultural use of the area prior to �- current uses. 4.0 SUMMARY AND CONCLUSIONS o One underground diesel storage tank was removed and disposed by a licensed hazardous waste transportation company under a hazardous waste manifest. Upon inspection of the tank and appurtenant piping after removal, it appeared that the tank and piping had maintained their integrity and no evidence of leakage or holes was observed. o Results of soil analyses indicated that the underground fuel storage tank has impacted site soils to a limited extent in the vicinity of the former dispenser island, with gasoline and diesel detected in the soil sample collected from this area (390 and 37 ppm of gasoline and diesel, respectively). However, it appears that potential impacts to underlying ground water or nearby surface waters are relatively low. -5- i-