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Mr Terry Tarditi <br /> July 25, 2006 <br /> Page 4 <br /> TPH-g TPH-g was detected in the samples from MW-2 and MW-4 at 72µg/L <br /> and $3 µg/L,respectively All other TPH-g concentrations were detected below <br /> their respective reporting limits The concentration of TPH-g in MW-2 is elevated <br /> above recent historical concentrations of<50µg/L The concentration of TPH-g <br /> in NAV-4 is within historical concentrations <br /> MtBE MtBE concentrations were detected in samples from three of the <br /> monitoring wells In MW-1, MtBE concentrations decreased from 43,000µg/Lin <br /> the first quarter 2006 to 7,000 µg/L this quarter MtBE concentrations increased <br /> from the first quarter 2006 levels in MW-2 from non-detect to 110 ug/L,and in <br /> MW-4 from 940 µg/L to 1,000 dig/L MtBE was not detected above the reporting <br /> limit of 0 5 �tg/L in MW-3 The concentrations of MtBE in wells MW-1 and <br /> MW-3 are below their respective historical ranges, and the concentrations of <br /> MtBE in wells MW-2 and MW-4 are above their respective historical ranges <br /> Other Oxygenates In addition to MtBE, other oxygenates were analyzed <br /> dnsopropyl ether (RIPE), ethyl-tertiary-butyl ether (EtBE), tert-amyl methyl ether <br /> (TAME) and tert-butanol Tert-butanol results for sample MW-1 and MW-3 were <br /> below their detection limits of 70µg/L and 5 0µg/L, respectively The <br /> concentration of tert-butanol in MW-2 (5 4µg/L)is elevated slightly above the <br /> historical concentration of below the detection limit of 5 0µg/L The concentration <br /> of tert-butanol for MW-4(39 �Lg/L) may be biased slightly high and is flagged with a <br /> I' DIPE and TAME were detected in MW-4 at 2 4µg/L and 0 66 dug/L <br /> respectively The concentrations of DIPE and TAME in MW-4 are within <br /> hitorical ranges No other oxygenates were detected in the monitoring wells above <br /> their respective reporting limits <br /> The following documents are enclosed with this letter <br /> Table 1 Historical Groundwater Elevation Data <br /> Table 2 Groundwater Flow Direction and Gradient <br /> Table 3 Histoncal Groundwater Analytical Data <br /> Figure 1 Site Map <br /> Figure 2 Groundwater Elevation Map,May 23,2006 <br /> Figure 3 Groundwater Constituent Map,May 23,2006 <br /> Figure 4 MtBE Isoconcentration Map,May 23,2006 <br /> Attachment A Field Data Sheets <br /> Attachment B Laboratory Analytical Reports <br /> p\3()000\130025-T&'I Trucking GW Morutortng 2006\Rcports\2nd-06gtr doc <br />