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41 Ago", 7 <br /> Z Z 2 <br /> V � � <br /> DO <br /> � O a <br /> y ` <br /> SERVICES, INCORPORATED <br /> a n <br /> MPDS-UN6981-12 <br /> August 21, 1996 <br /> Unocal Corporation <br /> 2000 Crow Canyon Place, Suite 400 <br /> P O Box 5155 <br /> San Ramon, California 94583 <br /> Attention Mr David J Camille <br /> RE Quarterly Data Report <br /> Unocal Service Station #6981 <br /> 4707 Pacific Avenue <br /> Stockton, California <br /> Dear Mr Camille <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 in 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 July 24, 1996 Prior to sampling, the wells were each purged <br /> of between 3 and 42 5 gallons of water During purging operations, the field parameters pH, <br /> temperature, and electrical conductivity were recorded on the purging/sampling data sheets which are <br /> attached to this report Once the field parameters were observed to stabilize, and where possible, a <br /> minimum of approximately four casing volumes had been removed from each well, samples were then <br /> collected using a clean Teflon bailer The samples were decanted into clean VOA vials and/or one-liter <br /> amber bottles, as appropriate, which were then sealed with Teflon-lined screw caps, labeled, and stored <br /> in a cooler, on ice, until delivery to a state-certified laboratory Field blank, Equipment blank and Trip <br /> blank samples (denoted as ES 1, ES2 and ES3 respectively) were also collected for quality assurance and <br /> control MPDS Services, Inc transported the purged ground water to the Unocal Refinery located in <br /> Rodeo, California, for treatment 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 Tables 2 and 3 The concentrations of Total Petroleum <br /> Hydrocarbons (TPH) as gasoline and benzene detected in the ground water samples collected this <br /> 2401 Stanwell Drive Suite 400, Concord, CA 94520 <br /> TEL (510) 602-5120 FAX (510)6891918 <br />