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' 14 December 1998 • AGE-NC Project No 96-0254 ' Page 3 of 4 ' 32 LABORATORY RESULTS OF GROUND WATER SAMPLES TPH-g was detected in samples collected from well MW-lA and MW-1B at concentrations of 220 ' and 2,000 micrograms per liter(µg/1),respectively TPH-d was detected samples collected from well MWAB ata concentration 160µg11 Benzene was detected in samples collected from wells MW-1A and MW-1B at concentrations of 15 ,ug/1 and 530 µg/1, respectively Toluene, ethyl benzene and ' xylenes were also detected in MW-1A and MW-1B at concentration as high as 260 µg/l (toluene, MWAB) MTBE was detected in the sample collected from well MW-113 at a concentration 9 9µg/1 TPH-g, TPH-d, BTEX and fuel oxygenates were not detected in other ground water samples collected during this sampling event Laboratory results of ground water samples analyzed for petroleum hydrocarbons are summarized in Table 2 and 3 The laboratory reports (MAI Laboratory ID 96081 to 96087), QA/QC reports and chain-of-custody forms are included in Appendix B The ground water sample collected from monitoring well MW-3 at 2420 Grant Line Road did not contain detectable concentrations of TPH or fuel oxygenates Benzene and toluene were detected at Ile concentrations 2 7 µg/1 and 1 6 4g11, respectively The laboratory report for 2420 Grant Line Road Well MW-3 is included in the Quarter ly Report - September 1998 dated 11 December 1998, for Grant Line Gas and Food 40 SUMMARY AND CONCLUSIONS IThe following conclusions were drawn from the results of this investigation I 0 Ground water at the site was encountered at a depth of approximately 7 to 8 feet bsg The prevailing ground water flow direction at the site is generally northward • Dissolved petroleum hydrocarbons and BTEX compounds were detected only in wells MW- IA and MWAB Therefore, the lateral extent of the dissolved phase plume is limited to the area of MW-lA and MW-1B • MTBE was detected at concentrations greater than the State of California Action Limit of 4µg/l in ground water samples collected from one of the wells The MTBE was encountered in a ground water sample at a concentration of 9 9 ug/l (MW-1B) • The concentrations of benzene exceed the state maximum contaminant level (MCL) of 1 ppb in wells MW-1B and MW-1A I i Advanced Geo Env iron mental Inc I