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<br /> • Thrifty Oil Co. Station #172
<br /> Paget
<br /> selected oxygenates (including MTBE) by EPA Method 826013, and for total petroleum
<br /> hydrocarbons as gasoline(TPHg)by EPA Method 8015M Ethanol and methanol were analyzed by
<br /> ASTM Method D285
<br /> TPHg,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 TPHg, benzene, and MTBE isoconcentration maps are
<br /> presented as Figures 3,4, and 5, respectively The highest concentrations of TPHg,benzene, and
<br /> MTBE in groundwater were found in monitoring well MW-11 (144,000 ug/L, 2,600 ug/L, and
<br /> 39,500 ug/L, respectively) The remaining site wells have very low to non-detectable constituent
<br /> concentrations
<br /> Since the third quarter of 1997,Thrifty has analyzed for oxygenates di-isopropyl ether(RIPE),ethyl-
<br /> tert butyl ether (ETBE), tert-amyl methyl ether (TAME), and tent-butanol (TBA), and MTBE by
<br /> method 8260B The alcohols(ethanol and methanol)were analyzed by ASTM standard D285 The
<br /> County of San Joaquin Public Health Services (CSJPHS) requested these analyses Laboratory
<br /> results indicate no alcohols or oxygenates (besides MTBE) were detected above the laboratory
<br /> detection limit,with the exception of TAME(13,100 ug/L)and TBA(13,400 ug/L)inwell MW-1I
<br /> It has been over three years without detecting the alcohol constituents in groundwater samples.
<br /> Therefore, Thrifty respectfully repeats its request for cessation of the requirement for
<br /> methanol and ethanol analysis at this site.
<br /> Remediation Status
<br /> Vapor Extraction System
<br /> On April 26,2001, a new Baker Furnace Thermal Oxidizer Unit was placed into operation with the
<br /> hour meter reading at zero Presently,the remediation system is connected to soil vapor extraction
<br /> wells VW-1, VW-2 (A,B),VW-3, VW-4 (A,B,C), VW-5 (A,B,C), and VW-6 (A,B,C) The vapor
<br /> wells operating during the third quarter of 2003 were VW-3, VW-5A,VW-5B(50%), and VW-5C
<br /> (25%) During the third quarter of 2003, the soil vapor extraction unit (VEU) operated
<br /> approximately 1,677 hours for a cumulative total of 17,912 hours Approximately 2,717 pounds of
<br /> hydrocarbons were removed during the third quarter 2003 for a total of 73,850 pounds as of
<br /> September 25, 2003 (Table 3)
<br /> Influent and effluent vapor samples were collected on July 9,August 14,and September 11,2003 In
<br /> addition, vapor samples were collected on August 14, 2003, from selected well heads The well
<br /> head, influent, and effluent vapor samples were analyzed for TPHg by EPA Method 8015, and
<br /> BTEX/MTBE by EPA Method 8021B Field Status Reports are included in Appendix C Copies of
<br /> the influent, effluent, and well head vapor sample laboratory analytical results are presented in
<br /> Appendix D
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