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l T Y 3 31 January 2000 AGE-NC Project No 97-0290 Page 8of10 4 2 3 Soil Vapor Extraction Supplemental Fuel Supplemental fuel (natural gas) is proposed for the operation of the selected VES unit An automatic air dilution module adjusts for the optimal combustion parameters by adding oxygen and/or supplemental fuel A natural gas meter is located at the site, but is not in current use 4 2 4 Soil Vapor Extraction Monitoring Activities The VES unit will be monitored using a photo-ionization detector(PID) and Dwyer DS-200 flow sensor to ensure optimal destruction of recovered hydrocarbon vapors, and to monitor cleanup progress The PID readings will be recorded from the influent end of the VES unit, and after destruction During the"start-up"period(approximately one week),operational parameters(air flow, combustion temperature, volume of processed vapor, oxygen level and the lower explosive limits) will be monitored on a daily basis Thereafter, the VES unit will be monitored weekly Vapor samples will be collected on a monthly basis from the influent and effluent of the VES The samples will be collected in Tedlar bags and transported under chain-of-custody procedure in a . chilled container to a DHS-certified laboratory 4 3 IN-SITU AIR SPARGING SYSTEM DESIGN Initiation of an IAS system is proposed within the"core"petroleum hydrocarbon-impacted area,IAS is proposed in conjunction with SVE at the site The proposed IAS system will be comprise of an electric air compressor to infect air beneath the water table using air sparging wells The compressor will provide between 5 and 15 pounds per square inch (psi) of air to each air sparge well The infected air will volatilize dissolved hydrocarbons in ground water, and force hydrocarbon vapors into the vadose zone, where they can be withdrawn by the SVE system The proposed IAS system will consist of the two existing IAS wells, seven new IAS wells and well VW 1 C, altered for sparging in addition to vapor extraction Approximate air sparging well locations are depicted in Figure 3 4 3 1 In-situ Air Sparging Well Installation Installation of seven IAS infection wells are proposed utilizing a truck-mounted drill rig equipped with 8-inch diameter hollow stem augers Hollow stern augers will be cleaned prior to advancement in each borehole Three borings will be advanced at an angle of approximately 25° from vertical,two Advanced GeoEnviron mental,Inc