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14 July 1991 Page 2 of 6 <br /> Groundwater samples collected from the monitoring wells were analyzed for TPH (Total <br /> Petroleum Hydrocarbons) by EPA method 8015 modified by gasoline, TRPH (Total Recoverable <br /> Petroleum Hydrocarbons) by EPA method 418.1, BTEX (Benzene, Toluene, Ethylbenzene, and <br /> Xylene) by EPA method 602, and total lead by EPA method 239.2. <br /> Results <br /> Groundwater Gradient. At the time of sampling, the groundwater gradient was 0.0059, <br /> and the observed flow direction was to the northwest. The gradient and flow direction are <br /> comparable to those observed in the third and fourth quarters of 1990. <br /> Chemical Analvses. The results of the groundwater analyses are listed in Table 1. <br /> Results of the previous rounds of sampling are also included in this table. No detectable levels <br /> of BTEX or TPH were found in any of the groundwater samples during the first quarter 1991 <br /> sampling. Trace levels of TRPH were observed in both upgradient and downgradienbt samples <br /> collected during this quarter, although no detectable levels of TPH were found in any samples. <br /> No lead was observed in any on the monitoring well water samples. <br /> Conclusions <br /> No detectable levels of BTEX, TPH or lead have been found in any of the groundwater <br /> samples collected adjacent the soil stockpile at the Stockton Soil Treatment Facility. Extremely <br /> low levels of TRPH have been detected. <br /> The groundwater gradient and direction have returned to typical values as reported in <br /> 1990. <br /> Attachments: <br /> 1. Roy. F. Weston, Inc. Laboratory Report, May 3, 1991. <br />