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` V? 196,000 µg/l- in April 1993 to a low of 110 µg/L measured in November U (� 2002 Current petroleum hydrocarbon concentrations (from groundwater samples collected in February 2003) are further discussed in Section 2 3 1 of t this report y �'�► �v Oxygenate compounds methyl-tert-butyl ether (MTBE), ethyl-tert-butyl ether (ETBE), and tert-amyl-methyl ether (TAME) have historically not been ry�� detected in site groundwater samples (see Table 5) MTBE was detected in one groundwater sample collected in November 2002, however, its detection is considered anomalous since it was never detected at any other time The compound tert-butanol (TBA) was detected in one groundwater sample collected from MW�1� ber 8, 1999 and from PZ-1 samples collected on October 18, 20 an4%eqo, 2001, but has never been detected in any other groundwater sample collected at the site until November 2002 The detection of TBA in two groundwater samples collected from wells MW-10 1 and MW-13 in November 2002 is considered anomalous because these wells are located in areas that are relatively unaffected from the leaking UST and TBA concentrations have never before been detected at these locations The oxygenate compound di-isopropyl ether (DIPE) has historically been measured at concentrations of 140 µg/L or less in samples collected from wells near the source of the release Current oxygenate concentrations are further discussed in Section 2 3 2 of this report 1 2.3.1 February 2003 TPH/BTEX Conditions Historicdata suggests that TPH and BTEX concentrations have significantly decreased due to natural biodegradation and to engineered remedial actions employed at the site The most recently collected groundwater sample analytical results are summarized in Table 6 BTEX compounds were only detected in groundwater samples collected on February 5, 2003 from wells MW-1, MW-7, SP-1, SP-2, PZ-1 and PZ-2, which are near the original gasoline UST's (see Figure 6) Detectable benzene concentrations ranged from 1 3 µg/1 ' in the sample from MW-7 to 490 µg/l from SP-1 Toluene ranged from 11 µg/l in the sample from well PZ-2 to 63 µg/l from MW-1 Ethylbenzene ranged from 7 2 µg/l in the sample from SP-2 to 580 µg/l from MW-1 Xylenes ranged from 46 µg/l in the sample from 1?7*-2 to 3,600 µg/l from MW-1 1i Remedial Action Completion Report The Earthgrains Company Facility 2651 South Airport Way Stockton California Prepared for rHE EART11GRAINS COMPANY Prcpared by Phlltp Services Corp H\ENV562400132\I21382EG%Stockton\Stockton\Remed�alComplettonReport doe April 14 2003