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Thr jo Oil Co. Station #172
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<br /> (BTEX) and selected oxygenates (including MTBE) by EPA method 8260B, and total petroleum
<br /> hydrocarbons (TPH-g)by EPA method 8015M modified for gasoline Ethanol and methanol were
<br /> analyzed by method D285 (Glycols-Alcohols)
<br /> TPH-g, BTEX, and MTBE concentrations appear in Table 1,while historical oxygenate and alcohol
<br /> results are presented in Table 2 Copies of groundwater laboratory reports and Chain-of-Custody
<br /> documents are included in Appendix B The TPH-g, benzene, and MTBE isoconcentration maps
<br /> are presented as Figures 2, 3, and 4. The highest concentrations of TPH-g and benzene in
<br /> groundwater were found in monitoring well MW-10 (23,900 ug/L and 11,300 ug/L, respectively)
<br /> The highest concentration of MTBE was detected in monitoring well MW-11 (5,570 ug/L)
<br /> Since the third quarter of 1997, Thrifty has analyzed for the requested oxygenates di-isopropyl ether
<br /> (DIPE), ethyl-tert butyl ethyl (ETBE),tert-amyl methyl ether(TAME), and tert-butanol (TBA), and
<br /> MTBE by method 8260B The following alcohols were also requested for analysis ethanol and
<br /> methanol Laboratory results indicate no alcohols were detected However, oxygenates detected
<br /> (besides MTBE)were TAME in well MW-10(55 ug/L)and TBA in wells MW-10 and MW-11 (788
<br /> ug/L and 1,210 ug/L, respectively)
<br /> Remediation Status
<br /> Vapor Extraction system
<br /> On April 12, 2001, a new Baker Furnace Thermal Oxidizer Unit was tested, and placed into
<br /> operation on April 26, 2001 with the hour meter reading at zero Presently, the remediation system
<br /> is connected to soil vapor extraction wells (VW-1, VW-2 (A,B), VW-3, VW-4 (A,B,C), VW-5
<br /> (A,B,C), and VW-6(A,B,C)) During this quarter the only wells operating were VW-2A, VW-213,
<br /> VW-3,VW-4A, VW-4C, VW-513,VW-5C, V W-6B, and VW-6C During the Fourth Quarter 2001,
<br /> the soil vapor extraction unit (VEU) operated approximately 1,801 hours for a total of 5,387 hours
<br /> Approximately 1130 pounds of hydrocarbons were removed during the Fourth Quarter 2001 for a
<br /> total of 28,340 pounds as of December 27, 2001 (Table 3)
<br /> Influent and effluent vapor samples were collected on October 18,November 14, and December 19,
<br /> 2001 In addition, samples were collected on November 28, 2001 from selected well-heads The
<br /> well-head, influent, and effluent vapor samples were analyzed for TPH-g by EPA method 8015, and
<br /> BTEX/MTBE by EPA method 8021 B A copy of the influent, effluent, and well-head vapor sample
<br /> laboratory analytical results are presented in Appendix D
<br /> A historical summary of hydrocarbons removed by vapor extraction is presented in Table 3 The
<br /> Field Status Reports are included in Appendix C
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