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' J I ' 17 September 2003 ! AGE-NC Project No 98-0448 Page 4 of 9 I ' 32 IN-SITU AIR SPARGING SYSTEM PROCEDURES I The IAS system utilizes a 5 horsepower, Speedaire (model no 5F229B) electric air compressor to ink ect 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-4B(screened 45 to 50 feet bsg) t ' 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 The infected 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dissolved hydrocarbons in ground water, and force hydrocarbon vapors into the vadose zone,where ' they can be withdrawn by the above SVE system I Generally,air pressure was discharged at shallow screened IAS wells AW-1 through AW-4 between ' 5 and 7 pounds per square inch (psi), or alternatively discharged to deeper screened well MW-4B between 13 and 15 psi A liquid-filled, air-guage was installed at each of the above well heads to monitor air pressure Utilizing a Solinst water level indicator and a YSI-50 dissolved oxygen meter, monthly measurements of ground water depth and dissolved oxygen from ground water monitoring wells MW-1, MW-2 and MW-6 were performed to determine if ground water mounding was I • occurring as a result of the above IAS activities (Table 6) On 17 June 2003,Wilkerson airpressure regulators(model no R18)were installed at each well-head ' of IAS wells AW-1 through AW-4 and MW-4B and enabled the ability to perform continuous air spargmg at all of the above referenced well heads in the IAS network system I33 COLLECTION AND ANALYSIS OF VAPOR EXTRACTION AIR FLOW SAMPLES I A total of eight extracted air flow vapor samples were collected on 20 March,April 15,May 15 and 23 June 2003 from the influent and effluent streams of the regenerative vacuum blower unit to measure concentrations of hydrocarbon vapor The samples were collected in Tedlar bags using a Ihand 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 McCambell Analytical Inc (MAI)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 8021B r • IAdvanced GeoEnvironmentai,Inc F