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I Ci ry � <br /> I31 May 2002 <br /> AGE-NC Project No 97-0290 <br /> IPage 4of7 <br /> I concentrations in the other, down gradient wells showed smaller changes Within the sparging well <br /> network, small change in the dissolved oxygen was observed in well MW-2 The dissolved oxygen <br /> data for each well measured is summarized in Table 1 <br /> I <br /> 32 SOIL-VAPOR EXTRACTION <br /> The carbon-SVE unit operated continually,24 hours a day,during the observation period Extraction <br /> flow rates were calculated to heave been as high as 35 scfin An induced vacuum(negative pressure) <br /> I of up to 22 inches of water was measured in the piping between the SVE blower and extraction wells <br /> (Table 2) <br /> I <br /> 33 ANALYTICAL RESULTS OF SOIL VAPOR SAMPLES <br /> TPH-g was detected from all influent SVE air flow samples at concentrations as high as 9,000 [Ig/1 <br /> TPH-g was detected in the 10 December 2001 effluent SVE air flow sample at a concentration of <br /> 12,000 pg/l, indicating almost no adsorption was occurring, subsequently the carbon media was <br /> changed After change-out,the maximum hydrocarbon concentration measured in samples from the <br /> effluent stream was 260 gg/l, indicating a minimum 95-percent rate of destruction while operating <br /> Ithe carbon vessel SVE system <br /> BTEX compounds except benzene were detected in all influent SVE air flow samples at <br /> I concentrations as high as 230 µg/1 (xylene, 10 December 200 1) Prior to carbon media change-out, <br /> BTEX compounds were detected in the 10 December 2001 effluent SVE air flow sample at 46 µg/l, <br /> 120µg/1,48 µg/1 and 300µg/1,respectively After change-out,maximum BTEX concentrations were <br /> I1 9 µg/l, 25 µg11, 4 8 µg11 and 28 µtg/l, in the 11 March 2002 sample <br /> The analytical results are summarized on Table 3 The laboratory reports(MAI Sample Numbers for <br /> I influent samples 58701,85702,89263,89264,0203205-001,0203205-002,0204268-001,0204268- <br /> 002 and CTEL Sample Numbers for influent samples 0112-081-1, 0112-081-2, 0202-048-1 and <br /> 0202-048-2) Quality Assurance and Quality Control (QA/QC)reports and chain-of-custody forms <br /> Iare included in Appendix C <br /> Since the initial change-out of the carbon media in December 2001, an additional carbon media <br /> change-out was performed in February 2002 <br /> Advanced GeoEnvironmental,Inc <br />