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• monitoring wells MW-2, MW-3R, MW-4, MW-5, MW-6, TB-1, TB-7, TB-8, and TB-10 on
<br /> August 15, 2001 Groundwater samples were obtained by EMC and delivered in a chilled state
<br /> following strict Chain-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
<br /> I
<br /> Starting in the third quarter of 1997, as required by the Central Valley Regional Water Quality
<br /> Control Board (CVRWQCB), samples were also analyzed for oxygenates by EPA Method 8260B,
<br /> and alcohols by EPA method D285 (Glycols-Alcohols) The seven oxygenates which were analyzed
<br /> are Di-isopropyl ether(DIPE),Ethanol,Ethyl tert-Butyl Ether(ETBE),Methanol, Methyl tert-Butyl
<br /> Ether (MTBE), Tert-Amyl Methyl Ether (TAME), and Tert-Butanol (TBA) A summary of
<br /> historical analytical sampling results for TPH-g, BTEX, and MTBE are provided in Table 1, and
<br /> oxygenates/alcohols results are summarized in Table 3 Copies of the EMC Field Status Reports
<br /> are presented in Appendix A, and copies of the laboratory analytical reports are contained in
<br /> 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 and
<br /> MTBE were in monitoring well MW-5 11,900 ug/L and 30,900 ug/L, respectively Benzene was
<br /> below the laboratory detection limit in all wells sampled All other oxygenates were below the
<br /> • laboratory detection limit, except for 4 6 ug/L methanol in well TB-12, and TBA concentrations of
<br /> 14 ug/L, 204 ug/L, and 6,400 ug/L to monitoring wells MW-2, MW-5, and TB-12, respectively
<br /> (Appendix B)
<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-I I (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, and TB-9 (A,B)
<br /> During this reporting period, the soil vapor extraction unit (VEU) operated approximately 1,636
<br /> hours and approximately 1,940 pounds of TPH-g were removed this quarter as of September 25,
<br /> 2001 (Table 2 and Appendix C) The cumulative system total to date is approximately 10,014 hours
<br /> of operation, and approximately 57,035 pounds of TPH-g removed The system was shut down for
<br /> quarterly water sampling on August 15, 2001 and restarted when sampling was completed, the same
<br /> day The system was again shut down on September 25, 2001 to replace the temperature controller
<br /> Vapor samples were collected from the system inlet, outlet, and selected site wells (Figure 5) on
<br /> July 17 and August 7, and from the influent and effluent only on September 4, 2001 The samples
<br /> is were analyzed for TPH-g by EPA method 8015M for gasoline, and BTEX/MTBE by EPA method
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