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_ I <br /> Field Report <br /> Confirmation Groundwater Sampling 4 <br /> Grantline Plaza <br /> Tracy, California <br /> On April 11, .,1991 ROS F. WESTON, .INC. (WESTON) performed a second round of <br /> :groundwater sampling at the Grantline Plaza site at 350 West Grantline Road in Tracy, <br /> }. California. This work was conducted in order to confirm the results of the previous round <br /> .,of sampling. The confirmation samples were collected using the same procedures as the <br /> ::first sampling program and were analyzed for Benzene, Toluene, Xylene, and Ethyl <br /> ,,Benzene (BTXE)by EPA Method 602 and for Total Petroleum Hydrocarbons as Gasoline <br /> (TPH-G) by EPA Method 8015 (Modified). Table. A-3 presents the measurements of <br /> physical parameters of pH, electrical conductivity, and temperature that were collected . <br /> from the purge water. <br /> IABLE A-3 <br /> f. <br /> Field Water Quality Measurements f <br /> End of Purge Values <br /> April 11, 1991 <br /> Well/Sample pH Temperature Conductivity <br /> 1 (°F) (umhos) .. <br /> MW-1 7.76 65.1 2130 <br /> MW-2 7.80 63.9 2070 <br /> MW-3 7.74 63.2 2630 <br /> Quality control/quality assurance procedures consisted of the collection and analysis of <br /> a decontamination rinse blank sample (equipment blank). This sample was labeled EB-1 <br /> and was collected after a normal decontamination procedure by pouring distilled water <br /> into the bailer used for sampling, then pouring the'water from the bailer into the sample <br /> bottles. This acts as a check on the decontamination of the bailer, ensuring that it has <br /> been effectively cleaned. <br /> li <br /> A - 8 <br /> ; <br />