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03 February 2009 AGE-NC Project No. 97-0343 Page 2 of 4 A Magnehelic vacuum gauge is attached to the inlet of the moisture knockout drum to measure vacuum pressure exerted on the extraction well,and a cumulative flow meter is utilized downstream of the carbon canisters to monitor air flow.In addition, during monitoring events, a totalizing-flow Blue White rotometer or Dwyer differential flow meter is utilized to measure air-flow rate at the influent port. I I 2.2, SOIL VAPOR EXTRACTION SYSTEM OPERATION The SVE system began operation on 19 January 2006, under San Joaquin Valley Unified Air Pollution Control District(APCD)permit 7331-1. The SVE system is inspected regularly(weekly) during operation, and monitored/sampled monthly. During each monitoring event, flow rate of extracted soil vapor(influent)was measured using a totalizing-flow Blue White rotometer or Dwyer differential flow meter.Vacuum potential was measured at the 2-inch influent line by the Magnehelic vacuum gauge.In addition,organic vapor concentrations in the influent stream(before entering the blower) and the effluent stream(after exiting the carbon treatment)were measured using an OVM. Field measurements,recorded at regular intervals during the fourth quarter of 2008,are summarized in Table 1. Soil-vapor effluent and/or influent samples were collected on 27 October, 10 November and 01 December 2008. Influent and effluent vapor samples were collected directly into Tedlar bags. Samples were labeled, placed in a dry cooler, and transported under chain of custody to Cal Tech Environmental Laboratories(CTEL)in Paramount, California, a State of California Department of Public Health-certified analytical laboratory. Each soil vapor sample was analyzed for: • Total petroleum hydrocarbons quantified as gasoline (TPH-g) in accordance with EPA Method 8015 Modified; and • Benzene,toluene, ethylbenzene and total xylenes(BTEX)and the fuel methyl tertiary-butyl ether (MTBE), in accordance with EPA Method 8260B. 3.0. FINDINGS During the fourth quarter 2008 (rebound testing), the SVE unit operated at an average air flow rate of approximately 87 CFM,generating an induced vacuum(negative pressure)at the piping between the blower and extraction well. The SVE unit operated from 27 October through 17 December 2008 for an EHD-approved rebound testing period to evaluate the site for closure. Advanced GeoEnvironmental,Inc.