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i� I -� Frontier Transportation, Inc. Well Installation Work Plan November 14, 2006 Page 2 1 _ l 10.5' bgs. I Groundwater samples were collected from MW-1 , MW-2, and MW-3 on August 30, 1996 and April 21 , 1997 by Twinning. Results are presented in Table 1 . In January of 1998, BER advanced four (4) groundwater monitoring wells (MW-4 through MW-7) to assess the extent of subsurface contamination beneath the site (See Figure 2, Site Layout Map). Soil samples were collected every five feet. Laboratory analysis of soil samples identified no detectable concentrations of TPH-g, BTEX, or MTBE. Groundwater samples were subsequently collected. Results are tabulated in Table 1 . In January 2000, BEH advanced two borings (B-5 and B-6), installed four additional j 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 (See Figure 2). 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 µg/kg as BTEX, and 10,600 gg/kg as MTBE at 10' bgs. Maximum soil vapor concentrations were identified at sample point V5 at 4' bgs. Groundwater samples were subsequently collected from all monitoring wells. Groundwater results are tabulated in Table 1 and soil vapor sample results are presented in Table 2 . — "' 74 ✓c is n o Ta.� /e- Z- 07 i ! In May 2002, BEH installed two additional groundwater monitoring wells (MW42 and MW-13) screened from 30' bgs to 40' bgs. Soil sample results identified maximum TPH-g, BTEX, and MTBE concentrations of 700 mg/kg, 115,000 gg/kg, and 25,000 µg/kg in soil collected from MW43 at 10' bgs. Soil concentrations attenuate by 99% at 15' bgs. No detectable TPH-g, BTEX, and MTBE were identified in MW-12. Also, monitoring well MW-3 was abandoned prior to excavation and removal of 325 tons of impacted soil and replaced by MW-3R In June 2003 , BEH installed an additional groundwater monitoring well (MW-14) screened from 30' bgs to 40' bgs. Soil sample results identified a maximum MTBE concentration ot1 ,020 µg/kg at 10' bgs using EPA Method 8260B. No detectable TPH-g and BTEX were identified in MW- 14?. - i In January 2004, BEH installed four additional groundwater monitoring wells. Deep monitoring wells MW45, MW- 16 and MW-18 were advanced to 40' bgs and screened from 30' bgs to 40 ' bgs. Shallow monitoring well MW47 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 III- �' I