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I l2002 3rd Quarter Groundwater Report SFrontier Transportation -1 '7 1102-194 P , November 26, 2002 � `14� Page 4 'I've i ' low of 100 µg/LL The last groundwater sample collected from MW-3 prior to abandonment detected dissolved TPH-g as 9,750 µg/L✓Dissolved TPH-g concentrations in MW-1 have attenuated from 1,800 pg/L in August 1996 and remained under 50 pg/L since January 2000 C Groundwater collected in October 2002 from thirteen groundwater monitoring wells identified dissolved TPH-g concentrations exclusively in MW-3R as 3,790 µg/L using EPA ' method 8015 modified The previous episode performed in June 2002 identified 3,310 µg/L as TPH-g in MW-3R All other monitoring wells identified no detectable concentrations of dissolved TPH-g from the October 2002 sampling episode Please see Figure 4 for recent dissolved TPH-g isoconcentration map yl � `� „�/ .P— Historically no detectable concentrations of dissolved BTEX were identified-in---'r monitoring wells MW-5, MW-6, MW-7, MW-8, MW-9, MW-10, and M_W=l'1 since initial groundwater testing began in each well Monitoring wells MW-1;MW-2, and MW-4 have remained non detect since at least July of 1999 Only monitoring well MW-3, which was replaced by MW-3R, contained dissolved BTEX from every groundwater sampling episode YA J 1 � ti3 No detectable concentrations of dissolved BTEX were identified in groundwater samples collected in October 2002 from monitoring wells MW-1, MW-2, MW-4, MW-5, MW-7, MW-8, MW-9, MW-10, MWA 1, MW-12 and MW-13 using EPA method 8020 Trace dissolved BTEX concentrations were identified in monitoring wells MW-6 exclusively as toluene at 0 7 µg/L / Groundwater collected from replacement well MW-3R identified dissolved BTEX as 846 7 pg/L, an increase from 792 6 µg/L identified in June 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 October 2002 sampling episode Monitoring well MW-1 identified dissolved MTBE concentrations at a new maximum of 5,800 µg/L, an increase from 230 4g/L in June 2002 and <5 µg/L during the previous seven monitoring episodes 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 Replacement well MW-3R identified dissolved MTBE as 3,100 µg/L,an increase from 2,600 µg/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 Appendix B) "`See Figure 6 for the recent MTBE isoconcentration Map 0 I i