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OB/18/2003 11:10 2098325jr WRIGHT ENVIRONMEN- PAGE 07 NOW, J� Wright r EnvironmerlW August 12, 2003 , SavTrust of Mary Gardena 67 E.I&smear.Tracy,CA 85371.1 525 2"d Street ft 20"33-076S Fax tag-=4':152 Santa Cruz, California 95060 Attn.: Ms. WinKred Alexander Re: Workplan for Soil Vapor Extraction Tasting Stefanoe Gasoline 1419 Charter Way, Stockton, CA Project No. 4233.3 Dear Ms. Alexander, Soil vapor extraction(SVE)has been proposed as an interim remediation measure to clean up petroleum hydrocarbon impacted vadose zone soils at the subject site(Figure - Location,Map). This workplan describes the installation of extraction wells and soil vapor monitoring probes and the protocol for conducting a SVE pilot test at dw subject site. The objective of the test is to assess the feasibility of SVT in removing chemicals'of concern(CDCs)that occur at depths of 12 to 35 feet in site vadose zone soils. The COC-5 include total petroleum hydrocarbons as gasoline(TPH-G};benzene,toluene, ethylbenzene,and xylenes(BTEX); 1,2 dichloroethane(1,2 DCA)and several fuel oxygenates detected in site soil or ground water. SVE Well Construction e Two exftu-tion wells will be constructed to target the silt/clay and sandy zones that hav: been identified at different depths in the source area. The proposed wells will be kwate,l within the area of highest soil contamination(Figure 2- Site Plan). Should the test shovr SVE to be feasible these wells will be utilized for interim soil remediation.The proposed exmictlon well specifications ars as follows: SilVclay zone-EW 1, 2-inch diameter,PVC Schedule 80,0.020 slot size,screened 12-:17 feet,TD 30 ft. Well terminated within silt zone. Sandy zone-EW-2,2-inch diameter, PVC Schedule 80, 0.020 slot size, screened 30-35 feet,TI)35 ft. V�ox_Xo—n itoring-Probes Three vapor monitoring probes will be installed at different depths to target the silt/clay, and sandy zones. The probes will be used to collect vapor samples and pressure/vacuur:i readings to monitor the effect of SVE.These probes may be nested in a single borehole should space constraints preclude installation at different radial distances from the extraction wells: P-1, 1-inch diameter,PVC Schedule 80,0.020 slot size,screened— 15-20 feet.