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<br /> Thrifty Oil Co. Station #172
<br /> Paget
<br /> monitoring wells MW-3 through MW-1 1, (except MW-8, which was abandoned) Groundwater
<br /> samples were obtained by EMC on February 12, 2003, and delivered in a chilled state, in an ice
<br /> chest, following strict Cham-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 as gasoline (TPH-g) by EPA method 8015M Ethanol and methanol were analyzed
<br /> 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 3,4, and 5, respectively The highest concentrations of TPH-g and MTBE
<br /> in groundwater were found in monitoring well MW-6 (164 ug/L and 86 ug/L,respectively) Benzene
<br /> was not detected in any of the groundwater monitoring wells sampled
<br /> Since the third quarter of 1997, Thrifty has analyzed for oxygenates di-isopropyl ether(DTPE), ethyl-
<br /> tert butyl ether (ETBE), tert-amyl methyl ether (TAME), and tert-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 10 ug/L TBA in well MW-6 It has been over one year without
<br /> detecting the alcohol constituents in groundwater samples Therefore, Thrifty respectfully requests
<br /> for cessation of the requirements for methanol and ethanol analysis at this site
<br /> Remediation Status
<br /> Vapor Extraction System
<br /> On Apn126, 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 first quarter were VW-2A,VW-2B,VW-3, VW-5A, VW-5B, and VW-5C On
<br /> March 6, 2003 the extraction manifold was modified to the following configuration for vapor
<br /> extraction, VW-3 and VW-5A, 100%, VW-5B, 50%, and VW-5C, 25% During the first quarter of
<br /> 2003,the soil vapor extraction unit(VELI)operated approximately 1,755 hours for a cumulative total
<br /> of 14,372 hours Approximately 10,910 pounds of hydrocarbons were removed during the first
<br /> quarter 2003 for a total of 64,296 pounds as of March 20, 2003 (Table 3)
<br /> • Influent and effluent vapor samples were collected on January 9, February 11, and March 13, 2003
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