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I26 February 2004 AGE-NC Project No 98-0448 IPage 4of10 3 2 IN-SITU AIR SPARGING SYSTEM PROCEDURES The IAS system utilized a 5 horsepower, Speedaire (model no 5F229B) electric air compressor to inject air beneath the water table From the outlet of the air compressor, a manifold network of one' inch diameter, schedule 80 PVC piping was installed underground to the well heads at IAS wells AW-1 through AW-4(screened 25 to 30 feet bsg)and IAS well MW-413(screened 45 to 50 feet bsg) A Wilkerson oil filter (model no M18) and Wilkerson air pressure regulator (model no R28) are installed at the outlet of the air compressor for added controls, Wilkerson air pressure regulators (model no R18) are installed at each IAS well-head to enable Independent control over the varying I pressures required, at each well, to eject the water from the well casing and resulting continuous air sparging at all of the above referenced wellheads in the LAS network system The injected air should volatilize dissolved hydrocarbons in ground water, and force hydrocarbon vapors into the vadose zone, where they can be withdrawn by the above SVE system Generally,airpressure was discharged at shallow screened IAS wells AW-1 through AW-4 between 5 and 7 pounds per square inch (psi), and to deeper screened well MW-413 between 13 and 15 psi A liquid-filled, air-guage was installed at each of the above well heads to monitor air pressure 33 COLLECTION AND ANALYSIS OF VAPOR EXTRACTION AIR FLOW SAMPLES A total of three extracted air flow vapor samples were collected on 09 October, 18 November and 29 December 2003 from the influent stream of the regenerative vacuum blower unit to measure concentrations of hydrocarbon vapor, a fourth set of extracted air flow vapor samples were collected on 28 January 2004 at the conclusion of the rebound test Effluent vapor samples were not collected this quarter and are no longer necessary due to the low concentrations of hydrocarbon vapor in the influent stream The samples were collected in Tedlar bags using a hand air-vacuum pump Following sample collection, the samples were properly labeled,placed in a covered container and I transported under chain-of-custody to a DHS-certified laboratory for analysis Each sample was analyzed within 72 hours of collection for TPH-g and BTEX in accordance with EPA Methods 8015C Modified and 802113, respectively 4.0. REBOUND RESPONSE TEST PROCEDURES Between 29 December 2003 and 28 January 2004, a rebound response test wasp erfortned at the site on selected wells to evaluate whether or not ground water `spikes' or significant increases in dissolved contamination would occur following the SVE/IAS hiatus in selected ground water monitoring wells, SVE wells or the SVE influent Advanced CeoEnvaronmental,Inc