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i 2005 3'Quarter Groundwater Report . Frontier Transportation,Inc. December 5,2005 Page 5 eight wells with dissolved TPH-g using EPA method 8015 modified. Dissolved TPH-g was identified at a maximum of 12,000 µg/L in MW-21 As in previous groundwater monitoring events, MW-1, MW-3R, MW-9,and MW-17 identified dissolved TPH-gas MW-2 was sampled ' due to presence of a hydrocarbon odor during gauging. Dissolved TPH-gas was identified in MW-2 at 1,060 µg/L -All three of the new monitoring wells (MW-19,MW-20 and MW-21) contained dissolved TPH-gas No other wells identified TPH-g Tpentratnons (5s' g/L). See ' Table 1. See Figures 6 and 7 d m _o vi 2- In past sampling events no detectKsLM1W-4,,MW-5, o trace conc�tration�(:5 8 µg/L)of dissolved BTEX were identified in monitoring w MW-6,MW-7;MW-8, MW-9,MW- 10, MW-11;MW-12 and MW-1 sininitial groundwater testing began in each well. Monitoring wells MW-I and W- ve remained at non-detect to trace levels since at least July ' of 1999 Monitoring well MW-13 contained 62 µg/L dissolved total BTEX in June 2002 but has remained non-detect since then'Newly installed monitoring wells MW-15 through MW-18 identified no detectable concentrations of dissolved total BTEX during the 2004 first and second ' quarter groundwater monitoring events. Only monitoring wells MW-3 and its replacement MW- 3R contained dissolved BTEX from almost every groundwater sampling episode. ' Detectable concentrations of dissolved BTEX were identified in monitoring wells MW-2; MW-3R,'MW-19 and MW-21 for the groundwater samples collected in September 2005—See Figure 8 for dissolved benzene in MW-1 and Figure 9 for MW-3R 'Analytical results from MW- 3R demo ted a significant decrease in total dissolved BTEX from 2216 µg/L in December 2003 to X14.9 µg/L in September 2005 Dissolved benzene was detected above the MCL in ' MW-2,MW-3R, MW-19 and MW-21 at 3 µg/L,9.1 µg/L, 3 µg/L and 814 µg/L, respectively No detectable concentrations of dissolved BTEX were identified in the groundwater samples collected from the remainung nine(9)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-9, ' MW-17, MW-19, MW-20 and MW-21) using EPA method 8260 from the third quarter 2005 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 2,540 µg/L in September 2005,which is a decrease from the maximum concentration of 8,100 µg/L in September 2004. (See Figure 1 I 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 analysts for replacement well MW-3R identified a maximum dissolved MTBE ' concentration of 6,000 µg/L in December 2003. Dissolved MTBE for September 2005 was