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0 C-9 a ED <br /> z z z z <br /> o N <br /> DOSERVICES, <br /> INCORPORATED <br /> I� qPd 0� <br /> DS-UN2859-07 <br /> S ay 24, 1995 <br /> Unocal Corporation JON 2 1995 <br /> 2000 Crow Canyon Place, Suite 400 ENVIRONMENT <br /> P O Box 5155 PEWIii i CESTM <br /> San Ramon, California 94583 <br /> Attention Mr Robert A. Boust <br /> RE Quarterly Data Report <br /> Former Unocal Service Station #2859 <br /> 1665 Pacific Avenue <br /> Stockton, California <br /> Dear Mr Boust <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 monitoring wells that were monitored and sampled during this <br /> quarter are indicated in Table 1 Prior to sampling, the wells were <br /> 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 <br /> Table 1 . The ground water flow direction during the most recent <br /> quarter is shown on the attached Figure 1 <br /> Ground water samples were collected on May 4 , 1995 . Prior to sampling, <br /> the wells were each purged of between 6 and 13 . 5 gallons of water. <br /> During purging operations, the field parameters pH, temperature, and <br /> electrical conductivity were recorded and are presented in Table 2 . <br /> Once the field parameters were observed to stabilize, and where <br /> possible, a minimum of approximately four casing volumes had been <br /> removed from each well, samples were then collected using a clean <br /> Teflon bailer The samples were decanted into clean VOA vials and/or <br /> one-liter amber bottles, as appropriate, which were then sealed with <br /> Teflon-lined screw caps, labeled, and stored in a cooler, on ice, until <br /> delivery to a state-certified Laboratory. MPDS Services, Inc. <br /> transported the purged ground water to the Unocal Refinery located in <br /> Rodeo, California, for treatment and discharge to San Pablo Bay under <br /> NPDES permit . <br /> ANALYTICAL RESULTS <br /> • The ground water samples were analyzed at Sequoia Analytical Laboratory <br /> and were accompanied by properly executed Chain of Custody documenta- <br /> tion The analytical results of the ground water samples collected to <br /> date are summarized in Table 3 The concentrations of Total Petroleum <br /> 2401 Stanwell Drive, Suite 300 Concord CA 94520 <br /> TEL (510)602-5120 FAX (510)689-1918 <br />