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S monitoring wells MW-2, MW-3R, MW-4, MW-5, MW-6, TB-1, TB-7, TB-8, and TB-10 on
<br /> May 15, 2001 Groundwater samples were obtained by EMC and delivered in a chilled state
<br /> 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 /> 826013
<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(RIPE),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 12,000 ug/L and 34,000 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 1 1 ug/L DIPE in well MW-2, 12 ug/L TAME in well MW-5,
<br /> 50 ug/L, 103 ug/L, and 1850 ug/L TBA in monitoring wells MW-2, MW-3R, and MW-5,
<br /> respectively (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-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) Well MW-5
<br /> was shut off on June 12, 2001
<br /> During this reporting period, the soil vapor extraction unit (VEU) operated approximately 1,805
<br /> hours and approximately 1,218 pounds of TPH-g were removed this quarter as of June 26, 2001
<br /> (Table 2 and Appendix C) The cumulative system total to date is approximately 10,794 hours of
<br /> operation, and approximately 55,095 pounds of TPH-g removed The system was shut down for
<br /> quarterly water sampling on May 9 and restarted on May 16,2001 The system was again shutdown
<br /> on May 22 to install a catalytic cell and new hour meter, and was restarted on May 24, 2001 (new
<br /> hour meter started at zero)
<br /> Vapor samples were collected from the system inlet, outlet, and seven selected site wells (Figure
<br /> 5) on April 17 and May 9, and inlet, outlet and four selected site wells on June 12, 2001 The
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