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6.0 IN-SITU VAPOR EXTRACTION AND DESTRUCTION BY INCINERATION As has been stated earlier soil contamination exists from beneath the tank excavation to the top of the ground water. Overexcavation during the intial tank removal, removed contaminated soil to the 25 foot depth. Prior to replacement of the new double contained fiberglass tanks and dispensing system, 4 inch and 6 inch SCH 40 PVC 0 .02 inch slotted pipes were placed vertically at the north corner and west corner of the excavation respectively and manifolded via underground to the treatment compound with SCH 40 2 inch and 4 inch PVC pipe. These pipes were to be used for future soil remediation. WEGE plans to utilize monitor well MW10 along with the 4 and 6 inch risers that have been placed in the tank excavation for soil vapor extraction. Monitor well MW10 has been connected to the treatment compound with 2 inch SCH 40 PVC pipe running beneath the surface. A needle valve with a sample port will connect this pipe to the steel manifold (vapor extraction manifold) that hooks into the blower to be used for vapor extraction. Also needle valves with sample ports will be used to connect the two tank excavation risers , monitor wells MW1 and MW2, the sediment tank, and the Air stripping "Convault" that will be connected to the vapor extraction manifold. Sample ports will also be positioned at the influent and effluent ends of the blower for obtaining vacuum/pressure and temperature readings and samples. The effluent will then proceed into the incinerator for destruction. Incineration of gasoline range hydrocarbons produces water vapor and CO2 . A sample port at the effluent of the incinerator will be used for obtaining sample, pressure and temperature readings, see Figure 8-Schematic of Vapor Recovery System. 6 .1 HYDROCARBON VAPOR SOURCE TEST Pri.or to start up of the ground water-vapor recovery system, a source test was performed on monitor well MW10 to determine the available hydrocarbons for vapor extraction. This source test was started at 3 PM on Friday, January 11 , 1991 and was shut down at 8 AM Tuesday, January 15, 1991 , lasting for a total of 89 hours r averaging a removal of 625 pounds of hydrocarbons per day for a total of 2313 pounds of hydorcarbons as gasoline removed during the test. 85 gallon acitvated charcoal tub scrubs were used as emission control and daily monitoring with a photoionizing detector (PID) was used to predict breakthrough. The PID indicated that breakthrough may be occuring Monday afternoon and a bag sample (tedlar bag) was obtained of the charcoal effluent at that time (5 PM) . Analysis of this sample was calculated early Tuesday morning and the sample showed break through had occurred and the test was shut down at 8 AM that morning. During the 10