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} 23 November 1998 AGE-NC Project No 95-0103 Page 4 of 7 ' from wells MW-1 and MW-3 at concentrations of 15µg/l and 23 ug/l,respectively Neither ETBE nor TAME were detected in samples collected from the site ' The analytical results of current and previous samples are summarized in Table 2 and Table 3 The laboratory report (MAI sample ID Numbers 96322 through 96328), quality assurance and quality control (QA/QC) data and chain-of-custody form are included in Appendix B 1 ' 34 IN-SITU AIR SPARGING Elevated concentrations of dissolved oxygen were detected in monitoringwells MW-1 and MW-4 and the ASO wells Dissolved oxygen concentrations in the remaining wells showed only slight changes The greatest changes of dissolved oxygen content were observed in monitoring wells closer -to the spargmg wells/pomts ' Over the last quarter of IAS mjection the average dissolved oxygen concentrations for wells ASO-1, MW-1,ASO-2 and ASO-3, were 111%, 78%, 103%and 101%, respectively Over the last quarter well MW-4 has had average dissolved oxygen concentrations of 13 6% The more distal down- gradient wells MW-2, MW-6, MW-3, MW-5 and MW-7 had average dissolved oxygen concentrations of 5%, 6 7%, 6 9%, 8 5% and 5 5%, respectively ' Two of the dissolved oxygen concentrations were measured while the IAS system was not activated, otherwise,the dissolved oxygen percentage would have probably been higher The dissolved oxygen ' data is summarized on Table 4 Sparging rates were measured at approximately 10 scfm during each monitoring event A minimum pressure of 15 psi was maintained for the air sparging flow rate 1 3 5 SOIL VAPOR EXTRACTION ' The SVE unit operated at varying rates during this quarter Extraction flow rates were calculated to range from 180 to 185 scfm Typically, the operation averaged 180 sen during the period An ' induced vacuum(negative pressure)of approximately 40 inches of water was measured in the piping between the blower and extraction wells The radius of a measurable vacuum at the outlying wellheads was noted to extend 90 feet from VW-1 to MW-3, with a transmitted vacuum force ' (potential) of 0 16 inches of water TPH-g was detected in the 22 July, 31 August and 01 October 1998 samples collected from the ' influent vapor stream at concentrations of 180µg/1,210µg/1 and 400µg/l, respectively BTEX compounds were detected in each of the soil-vapor samples However, benzene was not Advanced CeoEnvironmental,Inc.