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1 ' 2006 1" Quarter Groundwater Report Frontier Transportation, Inc. ' April 28, 2006 Page b ' Detectable concentrations of dissolved BTEX were identified in monitoring wells MW-�, MW-3R and MW-21 for the groundwater samples collected in March 2006 See Figure 8 for ' dissolved benzene in MW-1 and Figure 9 for MW-3R 'MW-2 identified BTEX only as ethylbenzene and xylene with a total of 489 µg/L J Analytical results from MW-3R demonstrated a decrease in total dissolved BTEX from 1,319 5 4g/L in December 2005 to 219 9µ9/ L in March s I 2006 MW-21 contained BTEX at 64,010 µg/L;a significant increase from<250 gg/L during the'O r previous monitoring event Dissolved benzene was detected above the MCL in MW-3R and MW-21 at 113 pg/L and 11,700 µg/L, respectively No detectable concentrations of dissolved ' BTEX were identified in the groundwater samples collected from the remaining eleven(11) momtoring wells See Figure 10 for the recent dissolved BTEX isoconcentration Map ' MTBE was identified above MCL in rune groundwater wells (MW-1, MW-2, MW-3R, MW-9 and MW-17 through MW-21) using EPA method 8260 from the first quarter 2006 ' sampling episode The current California Department of Health Services (CDHS) primary Maximum Contaminant Level (MCL) for MTBE in groundwater is 13 µg/L Monitoring well MW-1 identified dissolved MTBE concentrations at 415 pg/L in March 2006, which is a decrease m m frothe maximum concentration of 8,100 gg/L September 2004 (See Figure 11 for MTBE in'' r MW-i overtime) MW-2 increased threefold to 5,190 gg/L from 1,510 gg/L during the previous sampling event Monitoring well MW-3 identified a maximum dissolved MTBE concentration of r 29,400 gg/L in March 1998 �Thns well was abandoned in May 2002 Groundwater analysis for replacement well MW-3R identified a maximum dissolved MTBE concentration of 6,000 µg/L in December 2003 Dissolved MTBE to MW-3R for March 2006 was identified at 394 gg/L, a rdecrease from the previous sampling event at 2,310 pg/L (See Figure 12 for MTBE in MW-3R over time) rThe first quarter 2006 groundwater sampling identified decreases in dissolved MTBE in a MW-9 to 782 gg/L, to MW-17 to 54 7 µg/]L and in MW-19 to 24 2 pg/L MW-18, MW-20 and MW-21 identified increased dissolved MTBE at 53 5 pg/L, 1,250 gg/L, and 8,000 4g/L, e¢` r respectively Dissolved MTBE was detected above the MCL in all wells with detectable amounts- AD mountsAll shallow wells sampled on-site contained dissolved MTBE, MW-18 was the only deep well r containing detectable dissolved MTBE Dissolved MTBE was non-detect (<2 µg/L) in deep monitoring wells MW-13, MW-14, MW-15 and MW-16 See Fngure,13'for the recent shallow well MTBE Isoconcentration Map 14 \jx'1 j ,j 7 66 r Beginning in March 2004, all groundwater samples collected were analyzed for r oxygenates ETRE, TAME, TBA, DIPE, 1,2-DCA and EDB using EPA method 8260 Detectable concentrations of ETBE, TAME and TBA were identified MW-2 during March 2006-MW-2 • r r r