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First Quarter 2004
<br /> Thnfty#172
<br /> Apnl 21, 2004
<br /> Page 2
<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 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 (61,000 ug/L, 3,550
<br /> ug/L, and 156 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 dt-isopropyl ether (DIPE),
<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 /> standard D285 The County of San Joaquin Public Health Services (CSJPHS) requested these
<br /> ianalyses 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 1,000
<br /> ug/L in well 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 first quarter of 2004 were VW-3 and VW-5A (100%), VW-
<br /> 5B (50%), and VW-5C (25%) During the first quarter of 2004, the soil vapor extraction unit
<br /> (VEU) operated approximately 1,194 hours for a cumulative total of 20,800 hours
<br /> Approximately 7,490 pounds of hydrocarbons were removed during the first quarter 2004 for a
<br /> total of 84,585 pounds as of March 31, 2004 (Table 3) The hydrocarbon mass removal rates via
<br /> vapor extraction were 6 27 lbs /hour during the reporting period and overall 4 07 lbs/hour as of
<br /> March 31, 2004
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