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1 17 March 1997 AGE-NC Project No, 95-0100 Page 3 of 7 4.0. SCOPE OF WORK AGE proposes to install an in-situ soil vapor extraction system at the site. A thermal oxidizer will be installed and a 24-hour operation of the system is planned in order to maximize the efficiency.of the treatment. 4.1. SOIL VAPOR EXTRACTION SYSTEM DESIGN It is proposed that the recovered hydrocarbon vapor undergo a thermal destruction process. The proposed unit is a direct,fired thermal oxidizer SVE system. A typical diagram of the system is illustrated in Figure 3 - Proposed Vapor Extraction, System. The SVE system is connected through a manifold box to the vapor recovery wells and should be able to operate at 100 cubic feet per minute(cfin). The thermal oxidizer can be outfitted with a catalytic module and/or a heat exchanger to provide an effective destruction ratio at reduced concentrations of hydrocarbon vapor. The vapor will be extracted from both extraction wells using a vacuum blower and routed to the thermal oxidizer. Supplemental fuel (i.e., natural gas) will be added to maintain the optimal temperature for a maximum destruction rate of hydrocarbon vapors. Additional information on the proposed system is included with Appendix A. 4.1.1. SYSTEM LOCATION AND DESIGN The proposed VES unit will be located near the northeast corner of the grocery store on the site. This location will reduce the amount of trenching and piping needed to install the system and still allow for the use of the parking area above the impacted soil. A gated enclosure, approximately 5 feet by 10 feet, will secure the VES unit. Two-inch PVC piping will be installed from both of the VES wells to a moisture dropout drum. The Piping will carry hydrocarbon vapors from the VES well heads to.the VES unit. All PVC piping will be installed underground. A PVC ball valve will be installed in each line so that vapors can be drawn from each well screen independently. A plan of the proposed piping system and enclosed VES unit location are depicted in Figure 4 -Proposed PVC Piping System. 4.L2. SUPPLEMENTAL FUEL Supplemental fuel is required for the operation of the selected VES unit. An automatic air diluiion module adjusts for the optimal`combustion parameters by adding oxygen and/or supplemental fuel.