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i ' Report—Vapor Extraction 1 Air Sparge Remedial System Page 8 Former Bank of Stockton/Western Lift Site 1 Project No. 102.3 March 25, 2005 4.3 Vapor Extraction System The surface machinery is mounted on a covered, steel equipment skid designed to protect the equipment from the elements while allowing easy access for servicing and monitoring. The skid is located next to the electrical service that powers it, and is also adjacent to the vapor extraction manifold. The process air is extracted from the ground using a Fuji 7-HP regenerative blower or ring compressor capable of producing 250 SCFM at 10 inches of water vacuum, or 195 SCFM at 40 inches of water. It is expected that at any given time only one extraction well will be operated. This will allow the wells to be "cycled" to maximize the overall efficiency of the vapor extraction. In essence, as a given well's gasoline production declines to a low level, it will be taken off-line and replaced with another well. As the first extractor is allowed to be idle, the gasoline-impacted soil that it serves will be partially recharged, and eventually the well will be returned to production. Using this system, and assuming equal duty ' cycles, each well will be in a recharging state for about 85 percent of the time and will be in active production for 15 percent of the time. This method should allow the maximum feasible recovery of gasoline hydrocarbons. 1 4.5 Air Sparge System �. A 5 horsepower SpeedAire sparge compressor with an 80-gallon reserve tank was installed on the equipment skid. This compressor is capable of delivering up to least 5 scfm to the face of 4 sparge wells simultaneously. The normal operating manifold pressure is between 20 and 25 psig, which should result in pressure at the operating face of 5 to 10 psig. The compressor was equipped with a new pressure regulator and accumulator and secondary filters. ' 4.6 Carbon Filtration System The exhaust gas from the regenerative blower is directed to a battery of two, 2,000 carbon filters connected in parallel, and the exhaust from these filters is directed to a third 2,000 carbon filter connected in series. It is expected that each carbon unit will become saturated with about 500 to 700 pounds of gasoline. Sample ports were installed at points ' between the primary and secondary carbon units. A sample port was also installed at the base of the 10-foot-high exhaust stack. 1 • 2937 Veneman Ave., #B240 Geo-Phase Environmental Inc. Phone(209) 569-0293 Modesto, CA 95356 Fax(209) 569-0295 r