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y T <br /> � <br /> Z V Z Z = 2 <br /> 0 O 2 <br /> a q <br /> SERVICES IAICOAPOF3ATED <br /> v a v a <br /> T <br /> } J"" 1 '" ` 21 MPDS-UN0187-08 <br /> May 30, 1996 <br /> Unocal Corporation <br /> 2000 Crow Canyon Place, Suite 400 <br /> P O Box 5155 <br /> San Ramon, Califorrua 94583 <br /> Attention Mr Robert A Boust <br /> RE Quarterly Data Report <br /> Former Unocal Service Station #0187 <br /> 437 East Miner Avenue <br /> Stockton, California <br /> Dear Mr Boust <br /> This data report presents the results of the most recent quarter of monitoring and sampling of the <br /> monitoring wells at the referenced site by MPDS Services, Inc <br /> RECENT FIELD ACTIVITIES <br /> The monitoring wells that were monitored and sampled during this quarter are indicated on Table 1 <br /> Prior to sampling, the wells were checked for depth to water and the presence of free product or sheen <br /> The monitoring data and the ground water elevations are summarized in Table 1 The ground water <br /> flow direction during the most recent quarter is shown on the attached Figure 1 <br /> Ground water samples were collected on May 7, 1996 Prior to sampling, the wells were each purged <br /> of between 10 and 14 gaIlons of water During purging operations, the field parameters pH, tempera- <br /> ture, and electrical conductivity were recorded and are presented in Table 2 Once the field parameters <br /> were observed to stabilize, and where possible, a minimum of approximately four casing volumes had <br /> been removed from each well, samples were then collected using a clean Teflon bailer The samples <br /> were decanted into clean VOA vials and/or one-liter amber bottles, as appropriate, which were then <br /> sealed with Teflon-lined screw caps, labeled, and stored in a cooler, on ice, until delivery to a state- <br /> certified laboratory Field blank, Equipment blank and Trip blank samples (denoted as ES1, ES2 and <br /> ES3 respectively) were also collected for quality assurance and control MPDS Services, Inc <br /> transported the purged ground water to the Unocal Refinery located in Rodeo, California, for treatment <br /> and discharge to San Pablo Bay under NPDES permit <br /> ANALYTICAL RESULTS <br /> The ground water samples were analyzed at Sequoia Analytical Laboratory and were accompanied by <br /> properly executed Chain of Custody documentation The analytical results of the ground water samples <br /> collected to date are summarized in Table 3 The concentrations of TPH as gasoline and benzene <br /> 2401 Stanwell Drive Suite 400 Concord CA 94520 <br /> TEL (5 10) 602 5120 FAX (510) 689-1918 <br />