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i 1 <br /> 4.0 Fourth Quarter Groundwater Monitoring and Sampling <br /> 4.1 Monitoring <br /> The fourth quarter 1993 groundwater monitoring data were collected on <br /> ' December 16 and 17, 1993 Monitoring activities included measuring the <br /> groundwater elevation in nine onsite monitoring wells shown on Figure 4-1 <br /> Groundwater measurements were taken using an electronic oil/water interface probe <br /> ' Free product was not detected 1n any of the onsite monitoring wells Depth to <br /> groundwater and well depth measurements were recorded for each monitoring well <br /> ' and are listed 1n Table 1 Data collected were used to determine groundwater flow <br /> direction and gradient as shown on Figure 4-2 <br /> i 4.2 Sampling <br /> ' Field groundwater monitoring data (conductivity, pH, temperature, and <br /> turbidity) and groundwater elevation data were used to determine the volume of <br /> purge water to be removed from each monitoring well prior to sampling Samples <br /> were collected after physical parameters stabilized and a minimum of three well <br /> volumes of water had been removed Purge water and other investigation-derived <br /> wastes (IDW) were placed in Department of Transportation (DOT) approved 17E/H <br /> drums <br /> IDW will be sampled and submitted to the District's laboratory for waste <br /> ' characterization as specified in the July 1993 Additional Assessment and Groundwater <br /> Monitoring Work Plan (Work Plan) Upon receipt of the waste profile <br /> ' characterization results, the IDW will be appropriately disposed <br /> Groundwater samples were collected using Teflon bailers on December 16 and <br /> I 17, 1993, from seven of the nine monitoring wells (MW-1, MW-2, MW-3, MW-4, <br /> MW-6, MW-8, and MW-9) as specified in the September 1993 addendum to the <br /> ' Work Plan Groundwater samples were collected in three 40-milliliter (ml) volatile <br /> organic analyte (VOA) vials preserved with a hydrochloric acid solution and <br /> submitted for benzene, toluene, ethylbenzene, and xylenes (13TEX) and TPH-g <br /> ' analyses Additional groundwater was collected from MW-8 and MW-1 1n 500-m1 <br /> plastic bottles preserved with nitric acid and submitted for total lead analysis All <br /> samples were submitted to the District's laboratory along with the appropriate <br /> Chain-of-Custody forms <br /> 93822 East Bay Municipal Utility District <br /> 404296004thgtrgw 3 Stockton Service Center-Fourth Quarter 1993 <br />