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q <br /> FLVIW�D <br /> ! f 7 <br /> Wright <br /> Crt, EnvlronnlenW <br /> Inc. <br /> a <br /> Services, <br /> Trust of Mary Gardella 67 E. 10"'street,Tracy,CA 85376 <br /> 525 2"d Street Ph:2oM33-0758 Fax:209-832-5152 <br /> Santa Cruz, California 95060 <br /> Attn.: Ms. Winifred Alexander <br /> Re: Workplan for Soil Vapor Extraction Testing <br /> Stefanos Gasoline 1419 Charter Way, Stockton, CA <br /> Project No. 4233-3 <br /> Dear Ms. Alexander, <br /> Soil vapor extraction(SVE)has been proposed as an interim remediation measure to <br /> clean up petroleum hydrocarbon impacted vadose zone soils at the subject site (Figure 1- <br /> Location Map). This workplan describes the installation of extraction wells and soil <br /> vapor monitoring probes and the protocol for conducting a SVE pilot test at the subject <br /> site. The objective of the test is to assess the feasibility of SVE in removing chemicals of <br /> concern(CDCs) that occur at depths of 12 to 35 feet in site vadose zone soils. The COCs <br /> include total petroleum hydrocarbons as gasoline(TPH-G);benzene, toluene, <br /> ethylbenzene, and xylenes (BTEX); 1,2 dichloroethane(1,2 DCA) and several fuel <br /> oxygenates detected in site soil or ground water. <br /> SVE Well Construction Details <br /> Two extraction wells will be constructed to target the silt/clay and sandy zones that have <br /> been identified at different depths in the source area. The proposed wells will be located <br /> within the area of highest soil contamination(Figure 2- Site Plan). Should the test show <br /> SVE to be feasible these wells will be utilized for interim soil remediation. The proposed <br /> extraction well specifications are as follows: <br /> Silt/clay zone- EW-1, 2-inch diameter,PVC Schedule 80, 0.020 slot size, screened 12-27 <br /> feet, TD 30 ft. Well terminated within silt zone. <br /> Sandy zone - EW-2, 2-inch diameter, PVC Schedule 80, 0.020 slot size, screened 30-35 <br /> feet, TD 35 ft. <br /> Vapor Monitoring Probes <br /> Three vapor monitoring probes will be installed at different depths to target the silt/clay <br /> and sandy zones. The probes will be used to collect vapor samples and pressure/vacuum <br /> readings to monitor the effect of SVE. These probes may be nested in a single borehole <br /> should space constraints preclude installation at different radial distances from the <br /> extraction wells: <br /> P-1, 1-inch diameter, PVC Schedule 80, 0.020 slot size, screened— 15-20 feet. <br />