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SOIL VAPOR EXTRACTION PILOT STUDY WORK PLAN San Joaquin County Montgomery Ward Auto Service Center Public Health Services Department 5400 Pacific Avenue Stockton,CA Site Code 2163 I ■ Effective VES well configuration, ' ■ Required soil probe configuration, and w Baseline soil vapor concentration 3.4 TASK 4 - INSTALLATION OF PILOT VES ' 34 1 VES Well And Probe Layout I Figure 10 shows the proposed locations of the two VES wells and seven soil vapor probes Well VEW-1 is designed to be located at the center of the Impacted soil plume near B-11 Well VEW-1 will consist of a dual well configuration (VEW-lA and VEW-1B) VEW-1A will be screened between a depth of 10 feet bgs and 25 feet bgs while VEW-113 will be screened between 25 feet bgs and 35 feet bgs This dual-well completion will allow targeting specific depth intervals of the soil plume in this area ' Well VEW-2 will be screened from 15 to 35 feet bgs The wells will be completed with quick connect fittings at the well box for connecting to a temporary VES unit The well heads also will be equipped with sampling ports to allow measuring vacuum and collecting vapor samples The probes will be constructed to allow monitoring at specific distances away from the VEW wells and at specific depths below ground surface Probes SP-1 and SP-7 will be completed as dual probes At each location, there will be one probe at 20 feet bgs and another at 35 feet bgs (SP-lA and SP-7A at 20 feet bgs, SP-IB and SP-713 at 35 feet bgs) The other probes (SP-2 to SP-6) will all be completed at a single depth The relative distance of each probe from the two VES wells, and the proposed depth below ground surface, are planned to be as follows PROBE DISTANCE (FT) DISTANCE (FT) NUMBER FROM VEW-1 FROM VEW-2 DEPTH (FT) SP-1A 20 110 20 SP-l13 20 110 35 SP-2 10 80 25 SP-3 30 120 25 I SP-4 40 95 25 SP-5 110 20 25 SP-6 100 40 25 SP-7A 60 30 20 SP-713 60 30 35 R Well and soil probe construction field methodology are included in Appendix C 3 4 2 Soil Sampling/Testing For Plume Delineation In order to provide better control on the extent of impacted soils, the following 18 soil samples will be collected during the drilling of the extraction wells and vapor probes ■ Soil samples at 15, 20, 25, and 35 feet bgs at SP-113 and SP-7B, ■ Soil samples at 15,-20 and 25 feet bgs at SP-3 and SP-6, and Project No 1232 - 4 - ENVIRONMENTAL AUDIT, INC