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<br />• Chain-of-Custody procedures to a state certified laboratory and analyzed total petroleum
<br /> hydrocarbons as gasoline (TPH-g) by EPA method 8015 modified and for volatile aromatic
<br /> compounds of benzene, toluene, ethylbenzene, and xylenes, by EPA method 8020 A summary of
<br /> historical analytical sampling results are provided in Table 1 Starting in the third quarter of 1997,
<br /> as required by the Central Valley Regional Water Quality Control Board (CVRWQCB), samples
<br /> were analyzed for Oxygenates by EPA Method 8260 The seven oxygenates which were sampled
<br /> for are Di-isopropyl ether, Ethanol, Ethyl tert-Butyl Ether, Methanol, Methyl tert-Butyl Ether
<br /> (MTBE), Tert-Amyl Methyl Ether, and Tert-Butanol Copies of the EMC Field Status Reports are
<br /> presented in Appendix A, and copies of the laboratory analytical reports are contained in
<br /> Appendix B
<br /> The TPH-g, and MTBE isoconcentration maps are contoured in Figures 2 and 4 Benzene
<br /> concentrations are all below the laboratory detection limit and plotted on Figure 3 The highest
<br /> groundwater concentrations of TPH-g and MTBE were found in monitoring well MW-4 (620 ug/L
<br /> and 940 ug/L, respectively)
<br /> Remediation Status
<br /> On July 1, 1999, a Baker Furnace Thermal Oxidizer Unit was placed into operation with the hour
<br /> meter reading at 13,312 hours Presently, the remediation system is connected to soil vapor
<br />• extraction wells (MW-4, MW-5, TB-3, TB-4, TB-6, TB-7, TB-9 (A,B), TB-11 (A,B), and TB-12
<br /> (A,B)) During this reporting period, the soil vapor extraction unit (VEU) operated approximately
<br /> 895 hours during the Third Quarter 1999, and approximately 20,393 pounds of total petroleum
<br /> hydrocarbons for gasoline (TPH-g) were removed (Table 2)
<br /> Inlet vapor samples were collected biweekly on the first month of operating and monthly thereafter
<br /> Initial TPH-g concentration of the inlet to the VEU was 12,000 ppmv (laboratory data), on July 1,
<br /> 1999 The inlet vapor concentration dropped to 8,200 ppmv on September 1999
<br /> Effluent vapor samples were collected on July 1, July 12, July 27, August 24, and September 14,
<br /> 1999 The system was resampled on October 14, 1999 to verify the September 14 outlet data,
<br /> because the results have indicated a possible contamination of the vacuum pump used to collect
<br /> vapor sample from the effluent stream After resampling the outlet system, the TPH-g, benzene, and
<br /> MTBE were below the laboratory detection limits The effluent samples were analyzed for TPH-g
<br /> by EPA method 8015, and BTEX/MTBE were analyzed by using EPA method 8020 All vapor and
<br /> water samples collected at this site were sent to American Analytics for analysis A copy of the
<br /> vapor well-head laboratory analytical results are presented in Appendix C, and copies of vapor
<br /> inlet/outlet laboratory analytical results are presented in Appendix D
<br /> A historical summary of hydrocarbons removed by vapor extraction is presented in Table 2 Field
<br /> Status Reports are included in Appendix A
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