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27 October 2003 • AGE-NC Project No 98-0450 Page 9 of 17 vapor meter(OVM)equipped with a photo-ionization detector PID(Thermo Environmental 580a/b, 10 OeV, calibrated to isobutylene 100 ppb) ' A total of thirty-four soil-vapor samples were collected during the remediation period,between July 2000 and August 2003 Samples were analyzed for Total petroleum hydrocarbons quantified as gasoline (TPH-g) in accordance with EPA Method 8015 Modified and Volatile aromatic ' hydrocarbons benzene, toluene, ethylbenzene and total xylenes (BTEX) and methyl tertiary butyl ether (MTBE) in accordance with EPA Method 8020 The results of the laboratory analysis are ' summarized in Table 5 The SVE unit operated at varying rates during the observation period Extraction flow rates were calculated to range from 190 to approximately 200 cfm An induced vacuum (negative pressure) of approximately 28 to 30 inches of water was measured in the piping ' between the blower and extraction wells The SVE performance data is depicted in Table 6 On 22 February 2002,the soil vapor extraction pump motor on the electric catalytic oxidizer failed, ' the SVE unit was removed for service Because progressively lower concentrations of volatile hydrocarbons were extracted from the SVE, an active vacuum blower was installed at the site on 19 March 2002 The vacuum blower was monitored monthly The flow rate of extracted soil-gas � . (effluent)was measured using direct measure flow meter,vapor samples were collected and analyzed and vacuum potential was measured ' A compressor-based EnviroSparge IAS system was installed at the site on 18 June 2000,which delivered 10 standard cubic feet per minute (scfin) at a pressure of 10 pounds per square inch, adequate to displace the static water within each sparge well Elevated concentrations of dissolved ' oxygen were detected in monitoring wells BMW-3,BMW-4, BMW-5 and MW-5,which were used as observation wells within and outside the IAS network on the site Dissolved oxygen concentrations remained or decreased below pre-remedial levels in well BMW-1 and BMW-2 Sparging rates were measured at approximately 8 to 10 scfm during each monitoring event 4 0 REMEDIATION PROGRESS ' Hydrocarbons were detected in soil-vapor samples collected at the SVE unit at concentrations considered to be acceptable for successful on-going SVE remediation and the SVE unit operated over approximately 24 months The SVE ceased full--scale operation of 01 August 2003 A calculated ' total of 6,496 kilogram, 14,326 pounds or 2326 5 gallons of gasoline were removed over the SVE operation Trendlines plotted on a graph of TPH-g concentration versus time for the SVE remediation showed a more steeper decline, with a minor rebound occurring during; the final ' response analysis sampling events (Appendix B) 1 Advanced GeoEnvironmentai,Inc