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1 i <br /> 7 s Z <br /> z y y Z <br /> DOSERVICES, <br /> 0 <br /> INCORPORATED <br /> t <br /> a a <br /> r <br /> MPDS-UN5098-10 <br /> J�k :� 17, 19 9 6 <br /> Unocal Corporation <br /> 2000 Crow Canyon Place, Suite 400 <br /> P O Box 5155 <br /> San Ramon, California 94583 <br /> Attention- Ms Tina R Berry <br /> RE Quarterly Data Report <br /> Former Unocal Service Station #5098 <br /> 5606 Pacific Avenue <br /> Stockton, California <br /> Dear Ms Berry <br /> This data report presents the results of the most recent quarter of <br /> monitoring and sampling of the monitoring wells at the referenced site <br /> by MPDS Services, Inc <br /> RECENT FIELD ACTIVITIES <br /> The Unocal monitoring wells that were monitored and sampled during this <br /> quarter are indicated in Table 1 Prior to sampling, the Unocal wells <br /> were checked for depth to water and the presence of free product or <br /> • sheen The monitoring data and the ground water elevations for the <br /> Unocal wells are summarized in Table 1 . <br /> A point monitoring event was conducted with the consultant for the <br /> nearby Montgomery Ward site on March 11, 1996 The monitoring data <br /> collected for Montgomery Ward' s monitoring wells (provided by Environ- <br /> mental Audit, Inc ) are summarized in Table 4 The ground water flow <br /> direction in the vicinity of the Unocal and Montgomery Ward sites <br /> during the most recent quarter is shown, on the attached Figure 1 <br /> Ground water samples were collected from the Unocal wells on March 11, <br /> 1996 Prior to sampling, the Unocal wells were each purged of between <br /> 14 5 and 20 5 gallons of water During purging operations, the field <br /> parameters pH, temperature, and electrical conductivity were recorded <br /> and are presented in Table 2 Once the field parameters were observed <br /> to stabilize, and where possible, a minimum of approximately four <br /> 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 Tetlon-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 /> 2401 Stanwe#} Drive Suite 400 Concord CA 94520 <br /> TEL (510)602 5120 FAX (510)689 1918 <br />