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following strict Cham-of-Custody procedures to a state certified laboratory and analyzed total
<br /> petroleum hydrocarbons as gasoline (TPH-g) by EPA method 8015 modified and for volatile
<br /> aromatic compounds of benzene, toluene, ethylbenzene, and xylenes (BTEX), using EPA method
<br /> 8020 A summary of historical analytical sampling results are provided in Table 1 Starting in the
<br /> third quarter of 1997, as required by the Central Valley Regional Water Quality Control Board
<br /> (CVRWQCB),samples were analyzed for Oxygenates by EPA Method 8260 The seven oxygenates
<br /> which were analyzed are Di-isopropyl ether,Ethanol,Ethyl tert-Butyl Ether,Methanol,Methyl tert-
<br /> Butyl Ether(MTBE), Tert-Amyl Methyl Ether, and Tert-Butanol Copies of the EMC Field Status
<br /> Reports are presented in Appendix A, and copies of the Iaboratory analytical reports are contained
<br /> in Appendix B
<br /> The TPH-g, benzene, and MTBE isoconcentration maps are contoured in Figures 2 3, and 4 The
<br /> ,
<br /> analytical laboratory results with the highest groundwater concentrations of TPH-g, benzene and
<br /> MTBE was found in monitoring well MW-5, 28,000 ug/L, 5,800 ug/L, and 18,000 ug/L,
<br /> respectively The only other oxygenate with any detectable concentration was tert-Butanol in
<br /> monitoring wells MW-5 (8,700 ug/L) and MW-2 (930 ug/L)
<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-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)) MW-4 was turned off on January 18 and TB-11 (A,B) was turned off on March 28, 2000
<br /> During this reporting period, the soil vapor extraction unit (VEU) operated approximately 1,364
<br /> hours during the first quarter 2000, and approximately 3,291 6 pounds of total petroleum
<br /> hydrocarbons for gasoline (TPH-g) were removed this quarter (Table 2 and Appendix C) The
<br /> system was down on January 17 for maintenance The system was down again from February 9
<br /> through February 22, 2000 for replacement of a blower motor
<br /> Effluent vapor samples were collected on January 18 and March 21, 2000 The effluent samples
<br /> were analyzed for TPH-g by EPA method 8015, and BTEX/MTBE were analyzed by using EPA
<br /> method 8020 The effluent laboratory concentration results for January 18 and March 21, 2000
<br /> indicate TPH-g, benzene, and MTBE to be below method detection limits with the exception of I I
<br /> ppmV TPH-g and 0 13 ppmV benzene of the January 18 event Inlet vapor samples were collected
<br /> January and March(the system was down February), and well head vapor samples were collected
<br /> during the February and March sampling events Vapor samples collected at this site were sent for
<br /> analysis to American Analytics for the January and February events and American Environmental
<br /> Testing Laboratories for the March event A copy of the vapor well-head laboratory analytical
<br /> results, and copies of vapor 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 C
<br /> Thrifty will continue the current groundwater monitoring and sampling program, and operation of
<br /> the vapor extraction system
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