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' 20062 nd Quarter Groundwater Report ' Frontier Transportation, Inc. August 2, 2006 Page 6 ' Detectable concentrations of dissolved BTEX were identified)n monitoring wells MW- 3R and MW-19 for the groundwater samples collected in June 2006 Analytical results from ' MW-3R demonstrated a decrease in total dissolved BTEX from 219 9 µg/Lin March 2006 to 40 7 gg/L in June 2006 'Figure 9 demonstrates that the benzene concentrations in MW-3R fluctuate seasonally with maximums in winter and minimums in summer/MW-19 contained ' BTEX at <6 1 gg/L with detections of ethylbenzene and xylenes exclusively Dissolved benzene was detected above the MCL in MW-3R at 17 7 pg/L "No detectable concentrations of dissolved ' BTEX were identified in the groundwater samples collected from the remaining elev2--_(11) monitoring wells See Figure 10 for the recent dissolved BTEX Isoconcentration Map ' MTBE was identified above MCL in seven groundwater wells (MW-1, MW-3R, MW-4, MW-8, MW-9, MW-19 and MW-20) using EPA method 8260 from the second quarter 2006 sampling episode The current California Department of Health Services (CDHS) primary ' Maximum Contaminant Level (MCL) for MTBE in groundwater is 13 gg/L -Monitoring well MW-1 identified dissolved MTBE concentrations at 194 gg/L in June 2006, which is a decrease from the maximum concentration of 8,100 pg/L in September 2004 (See Figure 11 for MTBE in ' . MW-1 over time) Monitoring well MW-3 identified a maximum dissolved MTBE concentration of 29,400 µg/L in March 1998 /This 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 in MW-3R for June 2006 was identified at 217 µg/L, a decrease from the previous sampling event at 394 µg/L (See Figure 12 ' for MTBE in MW-3R over time) Dissolved MTBE was identified at maximums in MW-4 and ,,,,MW-8 at 724 µg/L and 2,890 gg/L, respectively MW-9 displayed a decrease in MTBE from a maximum of 1,710 µg/L in December 2005 to 762 pg/L in June 2006'MW-19 MTBE concentrations appear to be stable and were recently found at 25 1 µg/l, The maximum MTBE for MW-20 was 4,620 µg/L in September 2005, and the recent results were 427 gg/L Dissolved MTBE was identified in MW-18 at 7 9 µg/L, which is below the MCL No detectable concentrations of dissolved MTBE were identified in the remaining monitoring wells sampled See Figure j3 for the recent shallow well MTBE Isoconcentration Map I� Beginning in March 2004, all groundwater samples collected were analyzed for oxygenates ETBE, TAME, TBA and DIPE using EPA method 8260 Detectable concentrations I of ETBE were identified�MW-4 at 2 9 n/L in June 2006 MW-8 identified ETBE at 7 2 µg/L and TAME at 5 2 4g/L No other monitoring wells identified ETBE, TAME, TBA or DIPE ,The reporting limit for DIPS, ETBE and TAME was 2 µg/L and for TBA it was 10 pa See Appendix B'for laboratory analytical results • f