Laserfiche WebLink
z Z Z Z <br /> D10 <br /> N ` SERVICES, INCORPORATED <br /> a S2 <br /> 0❑O 4 <br /> MPDS-UN5421-02 <br /> July 27, 1994 <br /> Unocal Corporation <br /> 2000 Crow Canyon Place, Suite 400 <br /> P O Box 5155 <br /> San Ramon, California 94583 <br /> Attention Mr Edward C Ralston <br /> RE : Semi-Annual Data Report <br /> Unocal Service Station #5421 <br /> 7303 Pacific Avenue <br /> Stockton California <br /> Dear Mr Ralston <br /> This data report presents the results of the most recent semi.--annual <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 semi- <br /> annual period are indicated in Table 1 Prior to sampling, the 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 are <br /> summarized in Table 1 The ground water flow directions during the <br /> semi-annual period are shown on the attached Figures 1 and 2 <br /> Ground water samples were collected on June 7, 1994 As shown in Table <br /> 3 , the analytical results of the ground water sample from well MW4 were <br /> inconsistent with the previous analytical results for this well <br /> Therefore, MPDS Services, Inc resampled monitoring well MW4 on July <br /> 22, 1994 . Prior to sampling, the wells were each purged of between <br /> 10 . 5 and 15 . 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 Teflon-lined screw caps, labeled, and stored in <br /> a cooler, on ice, until delivery to a state-certified laboratory MPDS <br /> Services, Inc transported the purged ground water to the Unocal <br /> Refinery located in Rodeo, California, for treatment and discharge to <br /> San Pablo Bay under NPDES permit <br /> • <br /> 2401 Stanwell Drive, Suite 400 Concord,CA 94520 <br /> TEL (510) 602-5120 FAX (510)689 1918 <br />