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Site Characterization Report; 7500 West Eleventh Street, Tracy, CA. Page 16 3.7.1 Determination of Groundwater Elevations To prepare for the initial round of formal groundwater sampling and analysis, SJC i surveyed the elevations of the well casing and well-casing cover of each well relative to MSL. Before water in the well was disturbed by sampling, the depth from the top of the casing to the water table was measured using a water-depth meter. That data was used to { compute the groundwater table elevations. The depth to groundwater and the water table elevations are recorded in Table 3. f= 3.7.2 Groundwater Sampling Procedure Prior to recovery of a groundwater sample from a well, the well was purged of a minimum of 5 casing volumes. The purge water was temporarily held in 50-gallon steel drums that were staged on the 7500 West Eleventh Street property. Samples were recovered from each monitoring well using a dedicated bailer that was left suspended in the well casing for future use. Water brought to the surface in the bailers 4 : was decanted so as to completely fill clean glassware supplied by the laboratory. The . = sample vials were then tightly closed, labeled for identification, entered into chain-of- custody control, packed on chemical ice and held in refrigerated storage until transported to Sequoia's laboratory in Walnut Creek, California. 3.7.3 Laboratory Analyses Each groundwater water sample was analyzed at the laboratory for the following suite of analytes. Anal e Method of Analysis �-= Total Petroleum Hydrocarbons EPA Method 5030/8015M, Y (quantified as Diesel) j Total Petroleum Hydrocarbons EPA Method 8020A/8015M (quantified as Gasoline) Benzene EPA Method 8020 Toluene EPA Method 8020 Ethyl benzene EPA Method 8020 3 Total Xylene Isomers EPA Method 8020 Fuel Oxygenates* EPA Method 8260A } Ethylene dibromide (EDB) EPA Method 8260A sic