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and submitted to the District's laboratory for identical analyses as the original <br /> samples to provide a check on analytical procedures One split sample was collected <br /> ' from MW-9 and submitted to Anlab Analytical Laboratory for identical analyses as <br /> the original samples to provide a check on the District's laboratory procedures One <br /> 40 milliliter (mL)vial trip blank was submitted to the District's laboratory for BTEX <br /> analysis to provide a check on shipping procedures <br /> ' 4.3 Analytical Results <br /> Analytical results from fourth quarter 1994 sampling are summarized in Table 2 <br /> The laboratory data sheets are provided in the Appendix The quality control results <br /> are not included in Table 2, but are included in the Appendix. The duplicate, split, <br /> ' and trip blank quality control sample results confirmed that the samples had been <br /> collected, shipped, and analyzed appropriately Based on the data collected to date, <br /> the approximate petroleum hydrocarbon plume delineation is shown on Figure 4-3 <br /> A summary of analytical results from the quarterly monitoring events since the third <br /> quarter 1993 are is presented in Table 2. <br /> The fourth quarter 1994 sampling results are consistent with sampling trends <br /> previously established beginning in third quarter 1993 Concentrations of TPH-g and <br /> BTEX continue to fall at MW-S, in some cases by as much as an order of magnitude. <br /> Fourth quarter concentrations of TPH-g and BTEX are generally higher at MW-1 <br /> during the fourth quarter 1994 than during the previous quarter, continuing the <br /> moderate fluctuation exhibited between third quarter 1993 and third quarter 1994 <br /> Analytical results from fourth quarter 1993 through third quarter 1994 indicated <br /> sporadic concentrations of TPH-g and BTEX in groundwater and split samples <br /> collected at MW-9 Fourth quarter 1994 results indicate the highest levels yet <br /> detected, confirming the presence of hydrocarbons at the well Analytical data <br /> indicate concentrations of 150 µg/L TPH-g, 21 µg/L benzene, 0 9 µg/L toluene, <br /> 4 4 µg/L ethylbenzene, and 2 9 µg/L xylenes in the groundwater sample from MW-9 <br /> and similar concentrations in the split sample, also from MW-9 <br /> The proposed bioremediation system will be designed to ensure collection of the <br /> ' entire groundwater plume <br /> 9582 East Bay Municipal Uttlty District <br /> 40429600\4thgtr gw 5 Stockton Service Center-Fourth Quarter 1994 <br />