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1 <br /> t <br />' 2.7.2 Well Completion <br /> The well was completed as a 4-inch-diameter remediation well. Blank PVC casing was <br />' installed from surface grade to a depth of 10 feet. Perforated PVC casing (.020 screen)was <br /> installed from 10 feet below surface grade to total depth, except for a non-perforated blank <br /> section from 40 to 45 feet, where dense silty clay was encountered during drilling (Figure <br />' 3). Air and water flow through the dense zone is likely to be slower than through the <br /> underlying and overlying loose sand beds, and it may be necessary to install a separate <br /> extraction well screened only within this zone in order to extract hydrocarbon vapors from <br /> t it. <br /> 2.7.3 Soil Analysis <br /> tNine soil samples were analyzed by EPA methods 8015m and 8020 for total petroleum <br /> hydrocarbons in the gasoline range and for volatile aromatic hydrocarbons. TPH-g <br /> t concentrations ranged up to 12,000 mg/kg (ppm) at a depth of 35 feet (Table 1). <br /> Benzene and/or other volatile aromatics were present in all samples, ranging up to total <br /> concentrations in excess of 1,000 ppm. The laboratory report and chain of custody are <br /> included in Appendix B. <br /> 2.8 Slug Test <br /> ' A slug was performed erformed on four of the monitoring wells on November 18, 1993. The <br /> purpose of the test was to obtain the data needed to calculate the hydraulic conductivity and <br /> ' transmissivity of the aquifer. These parameters are used to evaluate possible groundwater <br /> remediation methods. The theory and methods behind the test and the results that were <br /> obtained are discussed in section 3.4. The test data are included in Appendix D, and aquifer <br /> ' calculations are presented in Appendix E. <br /> 2.9 Vapor Extraction Test <br /> A vapor extraction pilot test was conducted to evaluate the feasibility of vapor extraction <br /> technology for soil remediation at this site. The test was performed using vadose-zone well <br /> ' RW-1 as the extraction well. The well was first tested on November 16, 1993; however, due <br /> to equipment failure, this test was aborted after only three hours and repeated on December <br /> ' 17, 1993. The equipment, methods, and results of the test are included in section 6.1.2.2.5. <br /> Laboratory results of air samples collected during the test are presented in Appendix F. <br /> CW.6p-1 A"I 5—io".I... 12 <br /> A&A PAM-M-M.47 <br /> 1 <br />