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Thrifty Oil Co. Station #172
<br /> Paget
<br /> Quarterly Groundwater Sampling
<br /> As part of the groundwater monitoring program, groundwater samples were obtained from
<br /> monitoring wells MW-3 through MW-11, except MW-8 which was abandoned Groundwater
<br /> samples were obtained by EMC on February 21, 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 of benzene, toluene, ethylbenzene, and xylenes
<br /> (BTEX) and selected oxygenates (including MTBE) by EPA method 826013, 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. The highest concentrations of TPH-g, benzene, and MTBE in
<br /> groundwater were found in monitoring well MW-11 (141,000 ug/L, 17,500 ug/L, and 932 ug/L,
<br /> respectively)
<br /> Since the third quarter of 1997,Thrifty has analyzed for the requested oxygenates di-isopropyl ether
<br /> (DIPE), ethyl-tert butyl ether(ETBE),tert-amyl methyl ether(TAME), and tert-butanol (TBA), and
<br /> MTBE by method 8260B The following alcohols were also requested for analysis ethanol and
<br /> methanol Laboratory results indicate no alcohols were detected However, an oxygenate detected
<br /> (besides MTBE) was TBA in well MW-6 (12 ug/L)
<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)) During this
<br /> quarter the only wells operating were VW-2A,VW-213,VW-3,VW-4A,VW-4C,VW-5C, V W-613,
<br /> and VW-6C During the First Quarter 2002, the soil vapor extraction unit (VEU) operated
<br /> approximately 1,917 hours for a total of 7,304 hours Approximately 309 pounds of hydrocarbons
<br /> were removed during the first quarter 2002 for a total of 28,649 pounds as of March 28, 2002 (Table
<br /> 3)
<br /> Influent and effluent vapor samples were collected on January 24, February 7, and March 14, 2002
<br /> In addition, samples were collected on February 7, 2002 from selected well-heads, and an influent
<br /> is sample on March 29, 2002 The well-head, influent, and effluent vapor samples were analyzed for
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