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4 FIELD INVESTIGATION <br />' 4.1 Soil Boring and Sampling <br /> On September 17 and 18, 1996, an EMCON geologist observed Soil Exploration Services <br /> of Benicia, California, drill two vertical soil borings (BAR and B-2R) Soil boring BAR <br /> was converted to groundwater monitoring well MW-1 R, and soil boring B-2R was <br /> backfilled to the surface with neat cement On September 26, 1996, EMCON observed <br /> V&W Drilling of Rio Vista, California, drill three vertical soil borings (B-3R through B- <br /> 5R) These three borings were converted to dual completion vapor extraction wells VW-1 <br /> through VW-3 On October 11, 1996, EMCON observed Gregg Drfflmg of Martinez, <br /> California, drill one soil borings (B-6R) The boring was converted to vapor extraction <br /> well VW-4 The borings were located to evaluate residual hydrocarbons in the soil near <br /> the former USTs and former dispenser islands and to evaluate dissolved hydrocarbons in <br /> the groundwater beneath the site Soil borings were drilled using CME 75, Mobile B-61, <br /> and Simco drilling rigs EMCON field procedures are presented in Appendix A <br /> The total depths of the six vertical borings (B-IR through B-6R) ranged from 40 to 53 <br />' feet below ground surface (bgs) Groundwater was first encountered between <br /> approximately 31 and 38 feet bgs The boring locations are shown on Figure 2 <br /> Undisturbed soil samples were collected for classification and laboratory analyses at <br /> approximately 5-foot intervals or at soil lithology changes, from the ground surface to the <br /> total depth of the borings The soil samples were classified using visual and manual <br /> methods according to the Unified Soil Classification System During sampling, a <br /> photoiomzation detector (PID) was used to characterize the relative levels of hydrocarbon <br /> vapor emitted by soil samples Readings recorded in the field are shown on the logs of <br />' exploratory borings presented in Appendix B Drill cuttings were stockpiled on site and <br /> placed on and covered with plastic <br />' On September 26, 1996, a geologist from EMCON collected four soil samples from the <br /> stockpiled soil to be composited at the laboratory for analyses to evaluate disposal <br /> options On October 17, 1996, the drill cuttings were transported by Manley and Son <br /> Trucking, Inc , of Sacramento, California, to B & J Landfill in Dixon, California, for <br /> disposal <br />' SAC\N\PIZ\2613\26131000 1 BB 9NIb 2 Rcv 0 215197 <br /> 22613-100 001 4-1 <br />