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I2004 2nd Quarter Groundwater Report iFrontier Transportation ' August 9, 2004 Page 2 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 and results are tabulated in Table 1 In January 2000, BEII advanced two borings (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(See Figure 2, Site Layout Map for well locations) 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 µg/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 Results are tabulated in Table 1 In May 2002, BEII installed two additional groundwater monitoring wells (MW-12 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 µg/kg, and 25,000 µg/kg in soil collected from MW-13 at 10' bgs Soil concentrations attenuate by 99% at 15' bgs No 1 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, BEII installed an additional groundwater monitoring well (MW-14) ' screened from 30' bgs to 40' bgs Soil sample results identified a maximum MTBE concentration of 1,020 gg/kg at 10' bgs using EPA Method 8260B No detectable TPH-g and BTEX were identified in MW-l�4� 1n41 zed�"�"OF ho/40/1" y i 9�y9,o ' 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 MW-15 using EPA Method 8260B No other oxygenates or lead scavengers were ' detected The maximum TPH-gas detected was 17 mg/kg 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 ' 3.0 SITE GEOLOGY/HYDROGEOLOGY ' The site is located on the boundary of the Sacramento Valley and the San Joaquin Valley 1 I