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f <br /> 'A <br />' 28 January 2006 <br /> AGE-NC Project No 95-0121 <br />' Page 2 of 9 <br /> vacuum blower, the outlet from the vacuum blower is routed through two sequential 55-gallon <br />' carbon canisters A Magnehelic vacuum gauge is attached to the inlet of the blower Air flow is <br /> monitored using a Dwyer DS-200 flow sensor The flow rate is determined from the measured <br />' differential pressure and the piping diameter using a nomograph (Appendix A) The vapor stream _ <br /> y at the SVE inlet is monitored for the presence of organic vapor using an organic vapor analyzer <br /> (OVA) equipped with a photo-ionization detector (PID Thermo Environmental 580A, 10 0 eV, <br />' calibrated to isobutylene) Sampling ports are installed upstream of the vacuum blower inlet to <br /> recover influent soil vapor stream samples, and downstream of both carbon canisters to recover <br /> effluent stream samples to monitor the efficiency of hydrocarbon filtration SVE monitoring data is <br />' included in Table 2 <br />' 2 1 1 Collection and Analysis of Soil Vapor Samples <br /> Influent soil vapor samples were collected on 18 January, 16 February, 16 March, 13 April, and 04 <br />' May 2005 The samples were collected in Tedlar vapor bags using a vacuum pump attached to the <br /> influent sampling port The samples were labeled, placed in a chilled container, and transported <br /> under chain of custody to either Cal Tech Environmental Laboratories (CTEL), a California <br />' Department of Health Services (DHS) certified laboratory <br /> The samples were analyzed for <br /> • Tptal petroleum hydrocarbons quantified as gasoline (TPH-g) in accordance with EPA <br />' Method 8015 Modified, <br /> • Benzene, toluene, ethylbenzene, and total xylenes (BTEX) and methyl tertiary-butyl ether <br /> (MTBE) in accordance with EPA Method 8021 <br /> 2 12 Discontinuance of Soil Vapor Extraction System <br /> Due to consistent non-detections of hydrocarbon constituents in influent air samples taken during <br /> the first and second quarters 2005, and as directed in an EHD letter dated 25 April 2005, AGE shut <br />' down operation of the SVE system on-site on'11 May 2005 It was determined that the system had <br /> performed to maximum potential remediation, hydrocarbon concentrations had decreased beyond <br /> the level at which soil vapor extraction was effective <br /> Advanced GeoEnvironmental,Inc <br /> , <br /> I ' <br />