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' Quarterly Groundwater Report Frontier Transportation 0501-131 May 17, 2001 Page 3 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 rdissolved 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 µg/L in January 2000 using EPA method 8015 modified. BEII concludes that the damaged well cover caused the increase in TPH-m in MW-3 from November 1999 to May 2000. The casing of MW-3 allowed oily surface water to infiltrate the well. Dissolved TPH-m concentrations have remained non-detect at the site since September 2000, when the well cover was repaired. BEII, therefore, recommends that groundwater sample analysis for TPH-m be discontinued at the site. rLaboratory analysis identified dissolved TPH-d in monitoring well MW-3 at a maximum concentration of 33,000 µg/L, however it was reported as TPH-d and TPH-m combined. Since then, dissolved TPH-d concentrations in MW-3 have attenuated from >6,000 µg/L in 2000 to non-detect in April 2001. None of the remaining ten monitoring wells identified detectable concentrations of TPH-d. Should dissolved TPH-d remain non-detect for two additional ' monitoring episodes, then BEII will recommend that groundwater sample analysis for TPH-d be discontinued at the site. ' In addition, laboratory analysis of groundwater samples identified no detectable (<50 pg/L) concentrations of dissolved TPH-g in ten of the eleven wells sampled this episode. Groundwater collected from monitoring well MW-3 identified dissolved TPH-g concentrations ' as 809 µg/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 since then. Dissolved TPH-g concentrations in MW-1 have attenuated and remained under 50 pg/L since January 2000. Please see Figure 4 for recent dissolved TPH-g Iisoconcentration 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-11 using EPA method 8020. Monitoring well MW-3 exclusively identified total dissolved BTEX at a concentration of 230 Fig/L, a slight increase from 79 Fig/L identified in December 2000. The groundwater level rose 0.4' in the well, which may have dissolved adsorbed BTEX that was in the soil. Total dissolved BTEX concentrations in MW-3, however,