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� H <br /> ATTACHMENT S <br /> August 1989 <br /> A groundwater remediation/vapor abatement program was then <br /> set up, and the initial work performed involved removal of free <br /> product. In late 1985, and early 1987, groundwater remediation <br /> was accomplished by pumping the groundwater from pumping wells <br /> through an air stripper (Figure 2 for location of pumping wells) . <br /> Additionally, a vapor-abatement system was installed to prevent <br /> the possibility of hydrocarbon vapors entering the adjacent 7-11 <br /> store and video arcade. This system consisted of four vapor <br /> points (Figure 2) installed between the underground tank <br /> locations and the adjacent buildings. A continuous vacuum is <br /> frcm a 1 horsepower <br /> applied to the vapor points forced-air draft <br /> blower located in a treatment compound. The withdrawn vapors are <br /> then treated through activated carbon prior to discharge. Figure <br /> 3 shows a process schematic of the existing vapor-abatement <br /> of the <br /> system with air-sampling locations. Due to the efficiency <br /> venting system as it now exists, continued use of activated <br /> carbon as a treatment technology is cost prohibitive. <br /> SCOPE OF WORK <br /> From February 1987 to the present, the existing soil-venting <br /> system has been in continuous operation. However, falling <br /> groundwater levels (23 feet in 1987 to 35 feet in 1989) have <br /> resulted in a thicker vadose zone impacted with adsorbed hydro- <br /> carbons available to be treated using soil-venting technology. <br /> Additionally, monitoring wells MW-1 through MW-4 have <br /> predominantly gone dry. Since these wells are screened in a <br /> lower portion of what is now hydrocarbon-impacted vadose zone, <br /> Guoa;NuuArr•.0 <br /> ri'MiNOLOG}'.INC. <br />