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I ' Interim Corrective Action Pian '• Frontier Transportation, Inc. ' December 20, 2005 Page 2 ' In January of 1998, Blakely Environmental Investigations, Inc (BEII) advanced four (4) groundwater monitoring wells (MW-4 through MW-7) to assess the extent of subsurface ' contamination beneath the site Soil samples were collected every five feet Laboratory analysis of soil samples identified no detectable concentrations of TPH-g, BTEX, or MTBE ' In January 2000, BEII advanced two bonngs (B-5 and B-6), installed four additional groundwater monitoring wells (MW-8 through MW-11), and collected nine soil vapor ' samples for a soil vapor survey as part of an additional site assessment Soil sample analysis identified no detectable concentrations of petroleum hydrocarbons with the exception of boring B-6 Maximum contaminant levels in B-6 were identified 100 mg/kg as TPH-g, 2,343 ' gg/kg as BTEX, and 10,600 gg/kg as MTBE at 10' bg Maximum soil vapor concentrations were identified at sample point V5 at 4' bg Groundwater samples were subsequently collected from all monitoring wells ' In May 2002, BEII installed two additional groundwater monitoring wells (MW-12 and MVV-13) screened from 30' bg to 40' bg Soil sample results identified maximum TPH-g, BTEX, and MTBE concentrations of 700 mg/kg, 115,000 gg/kg, and 25,000 gg/kg in soil collected from MW-13 at 10' bg Soil concentrations attenuate by 99% at 15' bg No detectable TPH-g, BTEX, and MTBE were identified in MW-12 Also, monitoring well ' MVV-3 was abandoned prior to excavation and removal of 325 tons of impacted soil and replaced by MW-3R 1 In June 2003, BEII installed an additional groundwater monitoring well (MVV'-14) screened from 30' bg to 40' bg_ Soil sample results identified a maximum MTBE 1 concentration ofC1'0, 20 k at 10�bg using EPA Method 8260B No detectable concentrations of TPH-g or BTEkwere identified in the soil collected from MW-14 See Figure 2 for well locations AJ I V --4 v- J m r 1,0 4 - 61A VAk r t&prw" ' In January 2004 BEII installed four additional groundwater monitoring wells Deep monitoring wells MW-15, MW-16 and MW-18 were advanced to 40' bgs and screened from ' 30' bgs to 40' bgs Shallow monitoring well MW-17 was advanced to 20' bgs and screened from 5' bgs to 20' bgs Soil sample results identified a maximum MTBE concentration of ' 1,310 gg/kg at 10' bgs in MVV-15 using EPA Method 8260E No other oxygenates or lead scavengers were detected The maximum TPH-gas detected was 1 7 mglkg at 10' bgs in MW-15 using EPA Method 8015M No detectable BTEX was identified in the soil column ' for MW-15 through MW-18 See Figure 2 for well locations