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<br /> February 14, 2001 It should be noted that TB-8 apparently was inadvertently mislabeled as MW-8
<br /> in the laboratory reports Groundwater samples were obtained by EMC and delivered in a chilled
<br /> state following strict Cham-of-Custody procedures to a state certified laboratory and analyzed total
<br /> petroleum hydrocarbons (TPH-g) by EPA method 8015M modified for gasoline, and for volatile
<br /> aromatic compounds of benzene, toluene, ethylbenzene, and xylenes (BTEX), using EPA method
<br /> 8260B Starting in the third quarter of 1997, as required by the Central Valley Regional Water
<br /> Quality Control Board(CVRWQCB), samples were also analyzed for oxygenates by EPA Method
<br /> 8260B Alcohols were also analyzed by EPA method D285 (Glycols-Alcohols) The seven
<br /> oxygenates which were analyzed are Di-isopropyl ether (DIPE), Ethanol, Ethyl tert-Butyl Ether
<br /> (ETBE),Methanol,Methyl tert-Butyl Ether(MTBE), Tert-Amyl Methyl Ether(TAME), and Tert-
<br /> Butanol (TBA) A summary of historical analytical sampling results for TPH-g,BTEX, and MTBE
<br /> are provided in Table 1, and oxygenates/alcohols results are summarized in Table 3 Copies of the
<br /> EMC Field Status Reports are presented in Appendix A, and copies of the laboratory analytical
<br /> reports are contained in Appendix B
<br /> The TPH-g,benzene,and MTBE isoconcentration maps are contoured in Figures 2, 3, and 4 The
<br /> analytical laboratory results indicate that the highest groundwater concentrations of TPH-g,
<br /> benzene, and MTBE were in monitoring well MW-5 24,700 ug/L, 4,740 ug/L, and 17,700 ug/L,
<br /> respectively All other oxygenates were below the laboratory detection limit, except for 43,200 ug/L
<br /> TBA in monitoring well MW-5
<br /> Remediation Status
<br /> On July 1, 1999, a Baker Furnace Thermal Oxidizer Unit was placed into operation with the hour
<br /> meter reading starting at 13,312 hours Presently,the remediation system is connected to soil vapor
<br /> extraction wells MW-2, MW-4, MW-5, TB-3, TB-4, TB-6, TB-7, TB-9 (A,B), TB-11 (A,B), and
<br /> TB-12 (A,B) A map showing the extraction well layout is shown as Figure 5 During this quarter
<br /> the only wells operating were TB-3, TB-4, TB-6, MW-5, TB-9 (A,B) and TB-12 (A,B)
<br /> The vapor extraction system was restarted on January 9, 2001 after the installation of a new blower
<br /> motor During this reporting period,the soil vapor extraction unit (VEU) operated approximately
<br /> 1,259 hours (since January 9, 2001), and approximately 1,166 pounds of TPH-g (since January 9,
<br /> 2001) were removed this quarter (Table 2 and Appendix C) The cumulative system total to date
<br /> is approximately 8,836 hours of operation, and approximately 53,597 pounds of TPH-g removed
<br /> From March 20 through March 31, 2001 the remediation system was shut down due to rolling
<br /> blackouts by PG&E
<br /> Vapor samples were collected from the system inlet, outlet, and from seven selected site wells
<br /> (Figure 5) on February 8, and March 13, 2001 The samples were analyzed for TPH-g by EPA
<br /> method 8015M for gasoline, and BTEX/MTBE by EPA method 8021B The effluent vapor
<br /> laboratory results for February 8 and March 13, 2001 indicate TPH-g, benzene, and MTBE
<br /> concentrations to be below the method detection limit A copy of the vapor well-head laboratory
<br /> • analytical results, and copies of vapor inlet/outlet laboratory analytical results are presented in
<br /> Appendix D A historical summary of hydrocarbons removed by vapor extraction is presented in
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