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' 15 September 1998 AGE-NC Project No. 95-0100 ' Page 3 of 5 ' 3.0. FINDINGS 3.1. SOIL-VAPOR EXTRACTION The SVE unit operated at varying rates during the observation period. Extraction flow rates were ' calculated to range from 75 to approximately 90 scfm. Typically operation of the SVE averaged 85 scfm during the period. An induced vacuum (negative pressure) of approximately 15 to 20 inches of water was measured in the piping between the blower and extraction wells. An induced vacuum ' of approximately 0.15 inches was measured at well VW-2,a distance of 20 feet from the extraction well VW-1. Well VW-2 was not under a vacuum when the induced vacuum (potential) was measured. ' The SVE unit experienced poor operation during Feb m�Y� March and some of April due to adverse ' weather, natural gas delivery problems due to gas regulator failures. The first set of soil-vapor samples collected on 25 February 1998 had TPH-g detected in the influent ' vapor stream at concentrations of 2,600 parts per billion: ppb (reported in micrograms per liter: ugAL)-BTEX were detected at concentrations as high as 3 10 ppb(total xylenes). TPH-g was detected at 170 ppb in the sample collected from the effluent stream. Additionally, BTEX were detected in ' the vapor sample collected from the effluent stream at a maximum concentration of 20 ppb (total xylenes). Oxygenated fuel additives were not detected in these samples. Hydrocarbon concentrations detected in subsequent influent soil-vapor samples were as follows: • 28 April 1998: TPH-g was detected at 5,200 ppb; benzene at 2.2 ppb; toluene at 440 ppb; ' ethylbenzene at 140 ppb and total xylenes at 710 ppb. • 04 June 1998:TPH-g was detected at 5,000 ppb;toluene at 490 ppb;ethylbenzene at 180 ppb tand total xylenes at 820 ppb. • 30 June 1998: TPH-g was detected at 1,300 ppb; toluene at 44 ppb; ethylbenzene at 32 ppb and total xylenes at 180 ppb. The analytical results are summarized on Table 1. The laboratory report (MAI Sample Numbers. �� -86130/86131;:8$647,88648,90056/90057 and 91453/91454) Quality-Assurance and-Quality Control=== - (QA/QC) reports and chain-of-custody forms are included in Appendix A. Hydrocarbon concentrations as measured from the effluent stream in April and June indicated a 99 to 100 percent rate of destruction. While hydrocarbon concentrations measured from the effluent stream in February indicated a 93 percent rate of destruction:. Advanced GeoEnvironmcntal,Inc.