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r L � Y Site Background Information Former Stefano's Gas Station Page 6 of 6 Based on the results of the pilot test, ozone injection appears to be effective at well MW-3,but less or not effective at MW-I and MW-2. REMEDIAL ACTIVITIES Between 02 November 2004 and 03 June 2005,interim SVE remediation was conducted onsite;the system was continuously operated utilizing a regenerative vacuum blower to selectively apply an induced vacuum to vapor-extraction wells VW-1 through VW-5.Between 02 November 2004 and 03 June 2005,the SVE remediation system was operational for approximately 4,451.6 hours.During this operational period, differential pressures were observed to be between 2.4 and 9.4 inches of water at the SVE inlet which indicated the flow to be between 80 and 180 cubic feet per minute. During the testing period, the induced vacuum rates at the well heads ranged between 16 and 26 inches of water. Utilizing an organic vapor analyzer (OVA), hydrocarbon concentrations were measured at concentrations between 0 and 22 parts per million(ppm) at the SVE inlet. TPH-g was detected in 8 of the 10 influent SVE air flow samples at concentrations ranging between 220 micrograms per liter (µg/1) and 14,000 µg11. Various BTEX constituents were detected in all ten influent SVE air flow samples at concentrations as high as 670 µg/1 (xylenes, November 2004); however,benzene was only detected on one occasion(03 January 2005)at a concentration 2.4 µg/l. MTBE was not detected in any of the above influent SVE air flow samples at concentrations above laboratory reporting limits. The hydrocarbon mass removed during the SVE operating period was calculated using the equation:M=C-Q-t.During the above operational period,the weight,mass and volume of hydrocarbons extracted by the SVE system was calculated to be approximately 2,374.6 pounds, or equivalent to a volume of 383.7 gallons of gasoline. Ozone sparging has been conducted continuously onsite beginning in January 2006,along with the associated monthly system maintenance and monitoring activities. After periods of approximately six and twelve months of continuous operation, the ozone sparging system will be reevaluated and any modifications and/or additions to the system and its operation will be proposed and executed. Quarterly ground water monitoring activities will aid in determining the effectiveness of ozone sparging as the remedial technique, and estimating the remaining mass of dissolved hydrocarbons. Advanced GeoEnvironmental,Inc.