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1 <br /> I07 November 2005 <br /> AGE-NC Project No 98-0448 <br /> IPage 4 of 9 J , <br />' and are summarized in Table 6 <br /> 32 IN-SITU AIR SPARGING SYSTEM PROCEDURES <br /> Between June 2005 and September 2005, the IAS system utilized a 7'/2 horsepower, Westward <br />' (model no 5Z639) electric air compressor to infect air beneath the water table, ideally, the infected <br /> air should volatilize dissolved hydrocarbons in ground water,and force hydrocarbon vapors into the <br /> vadose zone, where they can be extracted by the above SVE system From the outlet of the air <br /> h compressor, a manifold network of one-inch diameter, schedule 80 PVC piping was installed <br /> underground to the well heads at IAS wells AW-1 through AW-4(screened 25-30 feet),AW-5 (30- <br /> 35 feet) and IAS well MW-413 (screened 45-50 feet) A Wilkerson oil filter (model no M18) and <br /> I Wilkerson air pressure regulator(model no R28)are installed at the outlet of the air compressor for <br /> added controls, Wilkerson air pressure regulators (model no R18) are installed at each IAS well <br /> head to enable independent control overthe varying pressures required to displace water within each <br /> air sparge well casing, resulting in continuous air sparging in the IAS network system <br /> Generally, air pressure was discharged at shallow screened IAS wells AW-4 and AW-5 between 4 <br /> Iand 8 pounds per square inch (psi), and to deeper screened well MW-4B between 6 and 8 psi A <br /> liquid-filled, air-gauge was Installed at each of the above well heads to monitor air pressure <br /> I <br /> 33 COLLECTION AND ANALYSIS OF VAPOR EXTRACTION AIR FLOW SAMPLES <br /> A total of three extracted air flow vapor samples were collected on 12 July, 09 August and <br /> 07 September 2005 from the influent stream of the regenerative vacuum blower unit to measure <br /> concentrations ofhydrocarbon vapor The samples were collected in Tedlar bags utilizing an electric <br /> air-vacuum pump <br /> Following sample collection, the samples were properly labeled, placed in a covered container and <br /> transported under chain of custody to a DHS-certified laboratory for analysis Each sample was <br /> analyzed within 72 hours of collection for TPH-g and BTEX/MTBE in accordance with EPA <br /> Methods 8015M Modified and 8021, respectively <br /> 4.0. FINDINGS <br /> AGE determined ground water flow direction and gradient from the field data collected on <br /> 29 September 2005,the contaminant impact to ground water was assessed from the laboratory data <br /> IAdvanced GeoEnvironmental,Inc <br />