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' 16 June 2004 AGE-NC Project No 95-0173 Page 4 of 9 a photo-ionization detector(PID Thermo Environmental 580B, 10 0 eV,calibrated to isobutylene), and 3) influent and effluent air flow vapor stream samples were collected from sampling ports installed upstream (influent) of the vacuum blower and downstream (effluent) of the catalytic ' oxidizer and submitted for laboratory analysis Field measurements were recorded at regular intervals and are summarized in Table 6 ' Between 09 September and 30 December 2003, an induced vacuum was applied to SVE wells (VW-I through VW-4)to extract and destruct hydrocarbon vapor from the subsurface Wells VW-5 through VW-7 were closed at the well-heads due to only trace levels of petroleum hydrocarbons tobserved from PID field measurements (Table 6) ' 32 IN-SITU AIR SPARGING SYSTEM PROCEDURES The 1AS system utilizes a 5 horsepower, Speedaire (model no 5F229B) electric air compressor to infect 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-7 and ground water monitoring wells MW-1 through MW-3 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 have volatilize dissolved hydrocarbons in ground water, and force hydrocarbon vapors into the vadose zone, where they can be withdrawn by the above SVE system I Between 09 September and 30 December 2003, air pressure was alternatively discharged from the air compressor to deeper screened wells AW-113 and AW-2B between 13 and 15 psi Utilizing a Solinst water level indicator and a YSI-50 dissolved oxygen meter, measurements of ground water depth and dissolved oxygen from ground water monitoring wells MW-1, MW-2 and MW-3 were performed to determine if ground water mounding was occurring as a result of the above IAS activities 33 COLLECTION AND ANALYSIS OF VAPOR EXTRACTION AIR FLOW SAMPLES Between 09 September and 30 December 2003, a total of fourairs of extracted air flow or va P p samples were collected from the influent and effluent of the SVE unit to measure concentrations of hydrocarbon vapor The air flow vapor 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 transported under cham-of-custody to McCampbelI Analytical Inc (MAI)m Pacheco, California Each sample was analyzed within 72 hours of collection for TPH-g, BTEX and MTBE • in accordance with EPA Methods 5030B/$015Cm Modified and 802 1B Advanced GeoEnvironmentai,inc