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6 2 Air-Sparging/Vapor-Extraction System Operation Overview <br /> The AS/VE system operated sporadically during the months of May and <br /> June 2003 By early July 2003, The engine had been serviced several <br /> times, and the repairs allowed the system to operate on a more continuous <br /> basis During the three months, ASE varied the air-flow and vacuum- <br /> influence on the wells in an effort to (a) reduce channeling and (b) <br /> concentrate on the areas of the site where elevated hydrocarbons in <br /> groundwater remained <br /> 6 3 Flow Rate <br /> While operating, the system injected an average of 33 cubic feet per <br /> minute (cfm) of air into the AS well manifold, and extracted an average of <br /> 50 cfm of petroleum-hydrocarbon laden air from the VE well manifold <br /> The 1C engine operated typically at 1900 RPM <br /> 6 4 Maintenance <br /> The IC engine was turned off each 220 to 250 hours of operation to <br /> perform routine maintenance activities Scheduled maintenance included <br /> lube, oil and filter for the engine and blowers, and draining of the moisture <br /> knock-out drum <br /> 6 5 Influent Air Sample <br /> On May 20, 2003, June 27, 2003 and July 22 2003, ASE collected a n <br /> influent air sample from the manifold of the VE wells The sample w a s <br /> analyzed by Kiff Analytical of Davis, California for TPH-G, BTEX, the seven <br /> fuel oxygenates and lead scavengers by EPA Method 8260B The analytical <br /> results for these samples are tabulated in Table Four The influent air <br /> sample analytical reports and chain of custody records are included in <br /> Appendix B <br /> 6 6 Mass Removed by AS/VE System <br /> The influent TPH-G concentrations in air were used to calculate the <br /> estimated mass removed from the vadose-zone beneath the site during <br /> May through July 2003 based on the volume of air removed The Monthly <br /> Mass Extraction Calculations are presented in Table Four It shows that <br /> . based on an average extraction flow rate of 50 cfm, and assuming a <br /> constant TPH-G concentration during the month in the influent air stream, <br /> Frank's One Stop Quarterly Report — July 2003 Sampling <br /> -4- <br />