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MPDS-UN5098-48 <br /> October 18, 1995 <br /> Page 2 <br /> field parameters pH, temperature, and electrical conductivity were <br /> recorded and are presented in Table 2 Once the field parameters were <br /> observed to stabilize, and where possible, a minimum of approximately <br /> four casing volumes had been removed from each well , samples were then <br /> collected using a clean Teflon bailer The samples were decanted into <br /> clean VOA vials and/or one-liter amber bottles, as appropriate, which <br /> were then sealed with Teflon-lined screw caps, labeled, and stored in <br /> a cooler, on ice, until delivery to a state-certified laboratory <br /> Field blank, Equipment blank and Trip blank samples (denoted as ES1 , <br /> ES2 and ES3 respectively) were also collected for quality assurance and <br /> control . MPDS Services, Inc . transported the purged ground water to <br /> the Unocal Refinery located in Rodeo, California, for treatment and <br /> discharge to San Pablo Bay under NPDES permit . <br /> ANALYTICAL RESULTS <br /> The ground water samples collected from the Unocal wells were analyzed <br /> at Sequoia Analytical Laboratory and were accompanied by properly <br /> executed Chain of Custody documentation The analytical results of the <br /> ground water samples collected from the Unocal wells to date are summa- <br /> rized in Table 3 . The concentrations of Total Petroleum Hydrocarbons <br /> (TPH) as gasoline and benzene detected in the ground water samples <br /> collected from the Unocal wells this quarter are shown on the attached <br /> Figure 2 Copies of the laboratory analytical results and the Chain of <br /> Custody documentation for the Unocal wells are attached to this report <br /> LIMITATIONS <br /> Environmental changes, either naturally-occurring or artificially- <br /> induced, may cause changes in ground water levels and flow paths , <br /> thereby changing the extent and concentration of any contaminants <br /> DISTRIBUTION <br /> A copy of tris L�purc should be sent zo zhe San Joaquin County Public <br /> Health Services, to the Regional Water Quality Control Board, Central <br /> Valley Region, and to Mr Frank Muramoto of Environmental Audit , Inc <br />