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Records regarding the UST removal at the subject site are incomplete, but indicate <br /> potential concern. According to a letter from the City of Manteca Public Works <br /> Department, a zone thirty feet in diameter, at least 12 feet deep, and saturated with <br /> gasoline was found during the removal of the USTs. The letter indicates that the <br /> contaminated soil should be excavated and either disposed of offsite or spread on the <br /> parcel. Further, the letter requires that the contaminated area be flushed with water to <br /> purge the area of vapors. These procedures could cause significant contamination of <br /> surficial soil or groundwater if carried out. However, the available file information does <br /> not indicate whether these recommendations were followed, or how the contaminated soil <br /> was in fact remediated. <br /> Based on the results of the subsurface investigation, contamination by gasoline and/or <br /> BTEX was not detected on the subject site. The levels of total recoverable petroleum <br /> hydrocarbons detected in soil samples from the borings may be associated with a clarifier <br /> or other structure associated with the former car wash. The detected hydrocarbons <br /> appear to be relatively immobile compounds in the oil and grease range. It is possible <br /> that the petroleum hydrocarbons detected by the EPA 418.1 analysis throughout the site <br /> are a result of the car washing operations and leaching of the asphalt pavement into the <br /> soil. Since there are no BTEX detections and since the petroleum hydrocarbon <br /> constituents are probably adsorbed to the soil particles, ATEC believes that these <br /> degraded hydrocarbons do not pose a significant risk to the groundwater. The lack of <br /> detectable contamination in the four groundwater samples is interpreted to indicate that <br /> groundwater beneath the site has not been impacted by the former presence of the USTs. <br /> 19 <br />