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' 4 FIELD INVESTIGATION ' 4.1 Soil Boring and Sampling ' On February 25, 1997, an EMCON geologist observed V&W Drilling, Inc , of Rio Vista, California, drill three vertical soli bonngs (B-1, B-2, and B-3) Soil boring B-1 was converted to vapor extraction well VW-1, and borings B-2 and B-3 were converted to ' groundwater monitoring wells MW-1 and MW-2, respectively The borings were located to evaluate residual hydrocarbons in the soil near the former UST and to evaluate dissolved hydrocarbons in the groundwater beneath the site The soil borings were drilled ' using a Mobile B-51 drilling rig EMCON field procedures are presented in Appendix A The total depths drilled for borings B-1, B-2, and B-3 were 26 feet, 38 5 feet, and 40 feet ' below ground surface (bgs), respectively Groundwater was first encountered in borings B-2 and B-3 at 23 feet and 25 feet bgs, respectively Groundwater was not encountered when drilling boring B-1 The boring locations are shown on Figure 2 Undisturbed soil samples were collected for classification and laboratory analyses at approximately 5-foot intervals or at soil lithology changes, from the ground surface to the ' total depth of the borings The soil samples were classified using visual and manual methods according to the Unified Soil Classification System During sampling, a flame ionization detector (FID) was used to characterize the relative levels of hydrocarbon vapor ' emitted by soil samples Readings recorded in the field are shown on the logs of exploratory borings presented in Appendix B Drill cuttings were stockpiled on site and placed on and covered with plastic ' On February 25, 1997, a geologist from EMCON collected four soil samples from the stockpiled soil to be uomposited at the laboratory for analyses to evaluate disposal ' options Following the receipt of analytical results for the composite soil sample, Manley and Son Trucking, Inc , of Sacramento, California, transported the dnUmg cuttings to Forward Landfill in Manteca, California, on April 24, 1997 i SA[.W\P12\260526051010 I RS-9Nb 2 Emcon 22605-101 001 4-1 Rev 0 814!97