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' 26 February 2004 <br /> AGE-NC Project No 98-0448 <br />' Page 3 of 10 <br />' 1,2-Dichloroethane (1,2-DCA), ethylene dibromide (EDB), tertiary butanol (TBA), di- <br /> Isopropyl ether (DIPE), ethyl tert butyl ether (ETBE), tert amyl methyl ether (TAME) and <br /> MTBE by EPA Method 8260 <br /> 3.0. SOIL VAPOR EXTRACTIONAN-SITU AIR SPARGE PROCEDURES <br />' Between 09 October 2003 and <br /> 29 December 2003, an SVE remediation system was conhnuousIy <br />' operated at the site, utilizing a regenerative vacuum blower to apply an Induced vacuum to wells <br /> VW-1, VW-2, VW-4 and MW-4A During this time, IAS remediation was continually operated at <br /> the site on wells AW-1 through AW-4 (screened 25 to 30 feet bsg) and MW-4B (screened 45 to 50 <br />' feet bsg)utilizing an air compressor to inject air beneath the water table Following the 29 December <br /> 2003 ground water and SVE air monitoring event, all SVE and IAS operations were temporarily <br /> suspended for a 1-month period for performance of a `rebound' response test, and re-started on 28 <br /> January 2004 Operation and design of the SVE and IAS systems for the site were described in <br /> Remedial Action Work Plan dated 07 July 2000, prepared by AGE, and approved by the EHD by <br /> letter dated 14 July 2000 <br /> I • <br /> 3 1 SOIL VAPOR EXTRACTION SYSTEM PROCEDURES <br /> The SVE system utilized a Fuji,3-horsepower regenerative vacuum blower to volatilize and extract <br /> adsorbed hydrocarbon vapor from the subsurface A manifold network of two-inch diameter, <br /> schedule 80 PVC piping was installed underground from wells VW-1 through VW-5 to the inlet of <br /> the regenerative vacuum blower, the outlet from the vacuum blower was routed through a vapor <br /> moisture knockout drum <br /> A Ma ehelic vacuum gauge was attached to the inlet of the blower, air flow was monitored at the <br /> � g g , <br /> inlet using a Dwyer DS-200 flow sensor A flow rate was determined from the measured differential <br /> pressure and the piping diameter using a nomograph (Appendix B) <br /> In order to monitor the efficiency of hydrocarbon,removal, 1) the SVE air flow of the influent <br /> stream was monitored routinely utilizing an organic vapor analyzer(OVA)equipped with a photo- <br /> ionization detector(PID Thermo Environmental 580B, 10 0 eV, calibrated to isobutylene), and 2) <br /> I influent air flow vapor stream sample was collected from sampling ports installed upstream <br /> (influent)of the vacuum blower and analyzed Field measurements were recorded at regular intervals <br /> and are summarized in Table 7 <br /> I <br /> a <br /> Advanced GeoEnvironmental,Inc <br />