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Wendy L. Cohen -2- 5 December 1994 <br /> Second Phase Investigation <br /> TES conducted the next phase of the site assessment in November 1992 in accordance with a work <br /> plan approved by the San Joaquin County PHS. <br /> Soil: TES installed nine soil borings and completed one as a monitoring well in November 1992 as <br /> shown in Attachment I. Soil analytical results of this work are shown in Table II. Soil from <br /> MW-1, B-2 and B-3 just above the water table contained TPH as kerosene (TPHk), TPHg, oil and <br /> grease, and BTEX. B-2 also contained TPH as diesel (TPHd) and TPH as motor oil near the <br /> surface. <br /> Ground Water. The water table was encountered in the soil borings at approximately nine feet <br /> below ground surface (bgs), showing a slight southwesterly gradient. TES took grab ground water <br /> samples from each boring and from MW-1. The results are shown in Table III. Ground water <br /> contained TPHk, TPHg and BTEX at levels up to 47,000, 6,500 ppb and 30 ppb, respectively, <br /> proximate to the reboiler unit. <br /> Comments <br /> Geology: The stratigraphy of the site needs to be evaluated below the water table to a depth of at <br /> least 20 feet bgs. <br /> Soil: The lateral and vertical distribution of petroleum hydrocarbon-contaminated soil needs to be <br /> determined. Since hydrocarbons have been detected at the water table at nine feet bgs, deeper <br /> borings or other appropriate means are needed to determine if there is soil contamination below the <br /> water table. <br /> Ground Water. The lateral and vertical extent of petroleum hydrocarbons also needs to be <br /> determined. Page 5-5 of the report states that an extraction method was used to analyze ground <br /> water samples from MW-1 for TPHd and TPHk. Since these constituents have volatile components, <br /> they should be evaluated using a purge and trap method. The ground water samples should also be <br /> analyzed for VOCs and semi-VOCs. In addition, since glycol compounds were detected in the <br /> effluent sample from the reboiler's discharge line, the ground water samples should be tested for <br /> these compounds using high performance liquid chromatography analysis. <br /> JDM:jdm/lsb <br />