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Report of Findings Frontier Transportation - March 12, 2004 Page 4 identified in the shallow soil from MW-15 at 10' b as 1 310 and at 15' b as 24Q lnrtP.�was g � µmg g µg/kg- S5 if MW-16 detected 132 µg/kg as MTBE at 15' bg MTBE was encountered in MW-17 at 15' bg �� and 20' bg at 101 µg/kg and 22 µg/kg MW-18 identified MTBE as 957 µg/kg at 10' bg and 45 µg/kg at 15' bg No MTBE was detected at 5' bg MTBE was identified at depth in MW-15 as 10 6 µg/kg exclusively at 35' bg, the depth of the second encountered groundwater in MW-15 In each well, the MTBE levels attenuated to non-detect or less than 22 µg/kg below 20' bg See Table 1 for Soil Sample Results and Appendix B for Laboratory Analytical Reports TPH-gas was detected at 10' bg exclusively in MW-15 and MW-18 at 1 7 mg/kg and 12 mg/kg, respectively No detectable concentrations of BTEX, lead scavengers, or other oxygenates were identified in any of theXsoil samples collected and analyzed JPl*4 Ja4 3� ♦� Groundwater monitoring will be conducted in the next quarterly sampling event to be performed in March 2004 The groundwater samples will be analyzed for TPH-g, BTEX, and I MTBE, TBA, DIPE, ETBE, TAME, 1,2-DCA and TBA using EPA methods 8015M and 8260B as requested by the PHS/EHD Results will be presented in the 2004 First Quarter Groundwater Report 5.0) CONCLUSIONS Based on soil sample results from monitoring wells MW-15 through MW-18, it is concluded that MTBE has impacted the subsurface soil along the capillary fringe and within the saturated zone of first encountered groundwater The depth of detectable MTBE concentrationso}S coincides with the depth to groundwater beneath the site The location of monitoring wells MW- 15 through MW-18 is approximately 130 feet west from the former UST location This supports that MTBE spread laterally in the soil via the groundwater gradient The MTBE can be adsorbed by the soil and act as a continuing source of MTBE contamination to groundwater _ I f 6.0) RECOMMENDATIONS Monitoring wells MW-15, MW-16, MW-17 and MW-18 identified elevated MTBE concentrations in soil approximately 130 away from the former UST area It is recommended that the impacted soil should be excavated to prevent the elevated MTBE in soil from acting as a ` - continual source to groundwater contamination IMonitoring wells MW-15 through MW-18 will be incorporated in future groundwater monitoring episodes Further groundwater analysis will provide information as to whether further delineation on the extent of MTBE impacted groundwater beneath the site is warranted _ 0