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<br /> Thrifty Oil Co. Station #172
<br /> Paget
<br /> monitoring wells MW-3 through MW-11, (except MW-8, which was abandoned) Groundwater
<br /> samples were obtained by EMC on November 20, 2002, and delivered in a chilled state, in an ice
<br /> chest, following strict Chain-of-Custody procedures to a state certified laboratory These samples
<br /> were analyzed for volatile aromatic compounds benzene, toluene, ethylbenzene, and xylenes
<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, respectively The highest concentrations of TPH-g and
<br /> benzene in groundwater were found in monitoring well MW-11 (5,170 ug/L and 190 ug/L,
<br /> respectively) The highest concentration of MTBE was found in groundwater monitoring well MW-
<br /> 6 (98 ug/L)
<br /> Since the third quarter of 1997, Thrifty has analyzed for oxygenates di-isopropyl ether(DIPE), ethyl-
<br /> tert butyl ether (ETBE), tert-amyl methyl ether (TAME), and tert-butanol (TBA), and MTBE by
<br /> method 8260B, and alcohol's(ethanol and methanol) by ASTM standard D285 as requested by the
<br /> County of San Joaquin Public Health Services (CSJPHS) Laboratory results indicate no alcohols
<br /> or oxygenates (besides MTBE) were detected above the laboratory detection limit, with the
<br /> exception of 24 uglL TBA in well MW-10
<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 wells
<br /> operating during the fourth quarter were VW-2A, VW-2B, VW-3, VW-5A, VW-5B, and VW-5C
<br /> During the fourth third quarter of 2002,the soil vapor extraction unit(VEU)operated approximately
<br /> 1,806 hours for a cumulative total of 12,617 hours On December 19, 2002, a new water flow meter
<br /> was installed Approximately 16,498 pounds of hydrocarbons were removed during the fourth
<br /> quarter 2002 for a total of 52,660 pounds as of December 26, 2002 (Table 3)
<br /> Influent and effluent vapor samples were collected on October 17,November 14, and December 12,
<br /> 2002 In addition, vapor samples were collected on November 14, 2002 from selected well heads
<br /> The well head, influent, and effluent vapor samples were analyzed for TPH-g by EPA method 8015,
<br /> and BTEX/MTBE by EPA method 8021B Copies of the influent, effluent, and well head vapor
<br />
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