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f ATTACHMENT B 6 August 1989 their use as soil-vent points would be cost effective and allow for increased remediation of hydrocarbon-impacted vadose zone soils. Monitoring wells MW-1, MW-2, MW-3 and MW-4 will he modified to serve both as vapor points, and groundwater monitoring wells. Figure 4 shows details of the modified monitoring wells. The wellheads will be capped off by a PVC plug, while an additional 2-inch PVC SCH 40 TEE and a ball valve with lateral 2-inch PVC piping connected to it will be installed. Lateral piping that will connect the modified monitoring wells (i.e. , the new vapor points) to the existing vapor lines to the treatment compound, will then be installed. Figure 5 shows the E � trenching schematic of the underground piping layout that will connect the proposed and existing vapor points to the treatment compound. As an alternative to activated-carbon treatment, a vacuum test was performed in ApKil, 19s9 to determine the feasibility of using an ORS Environmental Equipment catalytic Scavenger Incineration System (System) for vapor treatment. The results of the vacuum test showed that: o The total non-methane hydrocarbon concentrations (TPH) in the air being drawn from the vapor points and monitoring wells is approximately 39 percent of the Lower Explosive Limit (LEL, or 14,000 parts per million (ppm) = 100 percent LEL) . Enclosed in Attachment C are the laboratory results. This percent LEL of TPH in air is in the successful range of operation of the System, o The radius of influence of the vapor points was determined to be approximately 15 feet, yielding a total flow of 100 standard cubic feet per minute (scfm) through the vapor points and monitoring wells. A plot of the radius of influence of the vapor-extraction points is shown on Figure 5. ^�� GIif1C\ills';Cf'Fai I:CII"'omwl',INC.