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<br />' Thrifty Oil Co. Station #172
<br /> Page 2
<br />' samples were obtained by EMC on November 26, 2003, and delivered in a chilled state, in an ice
<br /> chest, following stnct Chain-of-Custody procedures to a state certified laboratory These
<br /> samples were analyzed for volatile aromatic compounds benzene, toluene, ethylbenzene, and
<br />' xylenes (BTEX) and selected oxygenates (including MTBE) by EPA Method 8260B, and for
<br /> total petroleum hydrocarbons as gasoline (TPHg)by EPA Method 8015M Ethanol and
<br /> methanol were analyzed by ASTM Method D285
<br />' TPHg, BTEX, and MTBE concentrations appear in Table 1, while historical oxygenate and
<br /> alcohol results are presented in Table 2 Copies of groundwater laboratory reports and chain-of-
<br /> custody
<br /> hain-ofcustody documents are included in Appendix B TPHg, benzene, and MTBE isoconcentration
<br /> maps are presented as Figures 3, 4, and 5, respectively The highest concentrations of TPHg,
<br /> benzene, and MTBE in groundwater were found in monitoring well MW-11 (38,600 ug/L, 5,670
<br />' ug/L, and 127 ug/L, respectively) The remaining site wells have very low to non-detectable
<br /> constituent concentrations
<br />' Since the third quarter of 1997, Thrifty has analyzed for oxygenates di-isopropyl ether (D1PE),
<br /> ethyl-tert butyl ether(ETBE), tert-amyl methyl ether(TAME), and tert-butanol (TBA), and
<br /> MTBE by method 8260B The alcohols (ethanol and methanol) were analyzed by ASTM
<br /> tstandard D285 The County of San Joaquin Public Health Services (CSJPHS) requested these
<br /> analyses Laboratory results indicate no alcohols or oxygenates (besides MTBE) were detected
<br /> above the laboratory detection limit, although the detection limit for TBA was elevated to 100
<br /> ug/L inwell MW-11 It has been over three years without detecting the alcohol constituents
<br /> in groundwater samples. Therefore, Thrifty respectfully repeats its request for cessation of
<br />' the requirement for 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
<br /> the hour meter reading at zero Presently, the remediation system is connected to soil vapor
<br /> extraction 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)
<br />' The vapor wells operating during the fourth quarter of 2003 were VW-3, VW-5A, VW-5B
<br /> (50%), and VW-5C (25%) During the fourth quarter of 2003, the soil vapor extraction unit
<br /> (VEU) operated approximately 1,744 hours for a cumulative total of 19,656 hours
<br />' Approximately 3,245 pounds of hydrocarbons were removed during the fourth quarter 2003 for a
<br /> total of 77,095 pounds as of December 30, 2003 (Table 3)
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