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Report of Findings . Frontier Transportation - ' March 12, 2004 Page 2 ' In January of 1998, 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 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 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'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 MW-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 µg/kg, and 25,000 µg/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 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' bg to 40' bg Soil sample results identified a maximum MTBE concentration of 1,020 µg/kg at 10' bg using EPA Method 8260B No detectable concentrations ofTPH-g or 9� 'BTEX rWe a identified in the soil collected from MW-14 See Figure 2 for well locations 3.0) SITE GEOLOGY/HYDROGEOLOGY hU,+�,,' The site is located on the boundary of the Sacramento Valley and the San Joaquin Valley ' within the west-central portion of the Great Valley Geomorphic province of California The Great Valley has been filled with a sequence of older to younger alluvium of Pliocene to ' Holocene age which overlay sedimentary rocks of Cretaceous to Tertiary age These sedimentary units, in turn, overlay a crystalline basement of Paleozoic and Mesozoic metamorphic and igneous rocks The shallow subsurface geology in the site vicinity is a heterogeneous mix of ' gravel, sand, silt, and clay(Reference, Site Characterization Re ort, Twining Laboratories, October 16, 1996) ' BEII encountered predominantly heterogeneous clays from 0' to 30' bg and fine-grained