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i i2002 4th Quarter Groundwater Report Frontier Transportation 0303-214 ' April 11, 2003 Page 4 ' 1,000 µg/L in MW-1 and MW-3 only Maximum dissolved TPH-g concentrations were identified in March 1998 as 42,000 gg/L in MW-3, which was the shallowest recorded groundwater depth in that well Since then, dissolved TPH-g concentrations have attenuated to a ' low of 100 gg/L The last groundwater sample collected from MW-3 prior to abandonment detected dissolved TPH-g as 9,750 gg/L Dissolved TPH-g concentrations in MW-1 have attenuated from 1,800 gg/L in August 1996 and remained under 50 gg/L since January 2000 Groundwater collected in January 2003 from thirteen groundwater monitoring wells ' identified dissolved TPH-g concentrations exclusively in MW-3R as 1,540 gg/L using EPA method 8015 modified The previous episode performed in October 2002 identified 3,790 gg/L as TPH-g in MW-3R All other monitoring wells identified no detectable concentrations of ' dissolved TPH-g from the fourth quarter 2002 sampling episode Please see Figure 4 for recent dissolved TPH-g isoconcentration map Historically no detectable concentrations of dissolved BTEX were identified in �'°x� � 1 monitoring wells MW-5, MW-6, MW-7, MW-8, MW-9, MW-10, and MW-11 since initial groundwater testing began in each well Monitoring wells �� 1, MW-2, and MW-4 have remained non detect since at least July of 1999 Only monito;oudwater w rl well MW-3, which was o-� ' replaced by MW-3R, contained dissolved BTEX from every, sampling episode No-�J"-tT4,4e4 14 rnw�l ' No detectable concentrations of dissolved BTEX were identified in groundwater samples collected in January 2003 from monitoring wells MW-1, MW-2, MW-4, MW-5, MW-6, MW-7, MW-8, MW-9, MW-10, MW-11, MW-12 and MW-13 using EPA methWoo 0 Groundwater ' collected from replacement well MW-3R identified dissolved BTEX as gg/L, a decrease from 846 7 gg/L identified in October 2002 See Figure 5 for the recent dissolved BTEX Isoconcentration Map MTBE was the only oxygenate identified in groundwater using EPA method 8260 from the fourth quarter 2002 sampling episode Monitoring well MW-1 identified dissolved MTBE concentrations 520 pg/L, a decrease from the maximum 5,800 pg/l, identified in October 2002 Dissolved MTBE was also identified in June 2002 as 230 gg/L The depth to groundwater in ' MW-1 was recorded as its lowest level (10 75') in June and October 2002, which coincides with the observance of increasing dissolved MTBE concentrations Monitoring well MW-3 identified a maximum dissolved MTBE concentration of 29,400 gg/L in March 1998 Replacement well MW-3R identified dissolved MTBE as 5,500 pg/L, an increase from 3,100 gg/L in October 2002 and 2,600 gg/L in June 2002 No detectable concentrations of other oxygenates were identified from groundwater sample analysis of the monitoring wells sampled using EPA method 8260 (See