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F1 • Quarterly Groundwater Report 1 ,6 Frontier Transportation j 0101-005 ' January 26, 2001 Page 3 Appendix A for Monitoring Well Field Logs). Groundwater samples were analyzed for TPH-d, TPH-g, TPH-m (total petroleum hydrocarbons as motor oil), BTEX, and MTBE using EPA ' methods 8015 modified for diesel, 8015 modified for gasoline, 8015 modified for motor oil, 8020 for BTEX, and 8260 for MTBE, respectively. Laboratory analysis results for all monitoring episodes are presented in Table 1. Recent analytical reports are included as Appendix B. ' Groundwater collected from all eleven monitoring wells identified no detectable dissolved TPH-m concentrations in all eleven monitoring wells. Historical groundwater data has identified dissolved TPH-m in monitoring well MW-3 exclusively. Maximum concentrations of dissolved L, TPH-m were identified in MW-3 as 33,000 µg/l, in January g 2000 using EPA method 8015 modified. ' Laboratory analysis identified dissolved TPH-d in monitoring well MW-3 exclusively as ' 6,470 µg/L in December 2000, a decrease from 6,670 µg/L in September 2000. None of the other ten monitoring wells identified detectable concentrations of TPH-d. In addition, laboratory analysis of groundwater samples identified no detectable (<50 µg/L) concentrations of dissolved TPH-g in ten of the eleven wells sampled. Groundwater collected from monitoring well MW-3 identified dissolved TPH-g concentrations as 1,570 pg/L ' using EPA method 8015 modified. Historical groundwater monitoring results have identified TPH-g concentrations above 1,000 µg/L in MW-1 and MW-3 only. Maximum dissolved TPH-g concentrations were identified in March 1998 as 42,000 pg/L in MW-3, which has attenuated by 96% since then. Dissolved TPH-g concentrations in MW-I have attenuated and remained under 50 µg/L since January 2000. Please see Figure 4 for recent TPH-g Isoconcentration Map. ' No detectable concentrations of dissolved BTEX were identified in groundwater samples collected from monitoring wells MW-1, MW-2, MW-4, MW-5, MW-6, MW-7, MW-8, MW-9, MW-10, and MW-1 1 using EPA method 8020. Monitoring well MW-3 exclusively identified total dissolved BTEX at a concentration of 79 µg/L_ Total dissolved BTEX concentrations in N4W-3 have attenuated by 99% since the maximum was identified as 8,350 pg/L in March 1998 ' when groundwater rose to its shallowest depth recorded (7.V bg). See Figure 5 for the recent BTEX Isoconcentration Map_ ' MTBE was identified in groundwater from one monitoring well (MW-3) only. See Figure 6 for the recent MTBE Isoconcentration Map. Groundwater collected from monitoring well MW-3 identified an decrease in MTBE concentrations from 120 µg/L to 31 µg/L, since the ' previous monitoring episode (September 2000) using EPA method 8260. However, MTBE concentrations have attenuated by 99% from the maximum concentration of 29,400 µg/L in t