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Quarterly Groundwater Report Frontier Transport.#ion ' 1100-131 November 8, 2000 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, 801.5 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 TPH-m were identified in MW-3 as 33,000 gg/L in January 2000 using EPA method 8015 modified. ' Laboratory analysis identified dissolved TPH-d in monitoring well MW-3 exclusively as 6,670 gg/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 gg/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 10,600 gg/L using EPA method 8015 modified. Historical groundwater monitoring results have identified ' TPH-g concentrations above 1,000 gg/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 has attenuated ' since then. Dissolved TPH-g concentrations in MW-1 have attenuated and remained under 50 gg/L since January 2000. Please see Figure 4 for recent TPH-g isoconcentration maps. ' 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 l using EPA method 8020. Monitoring well MW-3 exclusively identified ' total dissolved BTEX at a concentration of 2,003 gg/L. Total dissolved BTEX concentrations in MW-3 have attenuated by 76% since the maximum was identified as 8,350 gg/L in March 1998 when groundwater rose to its shallowest depth recorded (7.1' 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 150 gg/L to 120 gg/L, since the previous monitoring episode (May 2000) using EPA method 8260. However, MTBE ' concentrations have attenuated by 99% from the maximum concentration of 29,400 gg/L in