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2005 4"' Quarter Groundwater Report •� Frontier Transportation, Inc. February 13, 2006 Page 4 MTBE, tertiary butyl alcohol (TBA), di-isopropyl ether(DIPE), ethyl tertiary butyl ether (ETBE) and ternary amyl methyl ether(TAME)using EPA method 8260 Monitoring wells MW-19, MW-20 and MW-21 were also analyzed for 1,2-DCA and EDB Laboratory analysis results for all monitoring episodes are presented in Table 1 Recent laboratory analytical reports are included ' as Appendix B Historical groundwater data has identified dissolved TPH-m in momtonng well MW-3 exclusively Maximum concentrations of dissolved TPH-m were identified in MW-3 as 33,000 pg/L in January 2000 using EPA method 8015 modified In January 2000, the well cover for MW-3 was destroyed allowing oily surface water to infiltrate the well Blakely Environmental Investigations, Inc concluded that the damaged well cover caused the increase in TPH-m in MW- 3 from November 1999 to May 2000 Dissolved TPH-m concentrations have remained non-detect at the site since September 2000, when the well cover was repaired Therefore, groundwater sample analysis for TPH-m has been discontinued at the site ' Laboratory analysis identified dissolved TPH-d in monitoring well MW-3 at a maximum concentration of 33,000 gg/L in January 2000 However, the groundwater results were reported as TPH-d and TPH-m combined Since then, dissolved TPH-d concentrations in MW-3 ' attenuated to non-detect in April, August, and November of 2001 Groundwater analysis results from April 2002 identified dissolved TPH-d exclusively from MW-3 as 14,200 pg/L The groundwater level in MW-3 dropped to its lowest recorded depth (10 72') in April 2002 ` Monitoring well MW-3 was abandoned in May 2002 Replacement well MW-3R identified no detectable concentrations of dissolved TPH-d No other detectable concentrations of dissolved TPH-d were identified from laboratory analysis in any of the wells sampled since then, which ' includes the second quarter 2004 sampling episode Therefore, groundwater sample analysis for TPH-d has been discontinued at the site ' Historical groundwater monitoring results have identified TPH-g concentrations above 1,000 pg/L in MW-1, MW-3 and MW-3R Dissolved TPH-g concentrations in MW-1 had attenuated from 1,800 gg/L in August 1996 and remained under 50 gg/L from January 2000 to March 2005 (See Figure 6 for dissolved TPH-g over time in MW-1) 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 attenuated to a low of 100 pg/L The last groundwater sample collected from MW-3 in April 2002 pnor to abandonment detected dissolved TPH-g as 9,750 pg/L The maximum dissolved TPH-g ' concentration in MW-3R was 3,790 pg/L in October 2002 Since then, the dissolved TPH-g levels have decreased over time to lower levels ' Groundwater collected in December 2005 from thirteen(13) momtonng wells identified 1