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Work Plan for Refined Plume Definition and Management of Floating Product-7500 W 11th 5t., Tracy, CA. Page 26 <br /> to MSL. The computed groundwater table elevations will be used to produce a contour map <br /> of the groundwater table and determine the direction and magnitude of the groundwater flow <br /> gradient. <br /> 7.7.2 Well Purging <br /> After the depths to groundwater are measured, a small-diameter, submersible pump will be <br /> used to purge each groundwater-quality monitoring well of stagnant water. The pumped <br /> water will be discharged into 5-gal. pails, each of which will, in turn, be discharged into an <br /> open-topped, 55-gallon drum. Periodically during the well purging operation, the drum will <br /> be decanted into a 1000 gallon,polyethylene,holding tank secured in a fenced enclosure with ok <br /> a lockable gate that will be located on the 7500 West Eleventh Street property. <br /> During the purging procedure, the temperature, electrical conductivity and pH of the stream <br /> of purge water will be monitored by periodically checking those parameters using a multi- <br /> function electronic meter. Purging will continue until all three parameters stabilize, i.e., <br /> variations between measurements are less than 10%. The array of parametric results for each <br /> well will be recorded in field notes. <br /> 7.7.3 Groundwater Sampling Procedure <br /> y" After purging, samples will be recovered from each monitoring well to be sampled using a <br /> disposable bailer. Water brought to the surface in the bailers will be decanted via a discharge <br /> spigot valve placed in the bottom of the bailer so as to completely fill clean glassware <br /> "w supplied by the laboratory. The sample vials will then be tightly closed, labeled for <br /> identification, entered into chain-of-custody control and packed on chemical ice for transport, <br /> within 24 hours, to STL's laboratory in Pleasanton, California. <br /> 7.7.4 Groundwater Sample Analyses <br /> Each groundwater water sample will be analyzed for the following suite of analytes. <br /> Analyte Method of Anal <br /> Total Petroleum Hydrocarbons EPA Method 5030/8015 <br /> (quantified as Diesel) with pre-treatment by <br /> EPA Method 3630. <br /> r. <br /> Total Petroleum Hydrocarbons EPA Method 8260B <br /> (quantified as Gasoline) <br /> Benzene EPA Method 8260B <br /> Toluene EPA Method 8260B <br /> Ethylbenzene EPA Method 8260B <br /> SJC <br />