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3.6.6 In-Situ Air Sparging Feasibility Dissolved oxygen and groundwater depth data collected during the pilot study Indicate that IAS, combined with SVE should provide a viable alternative for remediation of Impacted groundwater at the site The groundwater depth was Increased (depressed) as much as 144 feet in ASO-1 (located approximately 3 feet from AS-1), groundwater depth decreased as much as 0 20 feet in ' ASO-2 No significant change in groundwater depth was anticipated in ASO-3 and therefore, groundwater depth was measured only once ' Dissolved oxygen in groundwater was measured in the IAS observation wells at several intervals throughout the IAS test (Table b) In ASO-1, dissohed oxygen ranged from 84 1% to 87 4%, in ASO-2, dissolved o\ygen ranged fi om 16 Oslo to 32 9cc,, dissolved o\ygen \\as ' rineasuied at 62 4% in ASO-3 The measured concentrations of dissohed o\ygen indicate a significant increase compared to normal dissolved o\ygen concentrations of less than jo% It appears that the effective radius of influence for the air spaiging \\ells ori-site Islay be as cleat as 70 to 30 feet ' The increased dissohed oxygen and the change in groundwater depths indicate that the injected air had an influence on all IAS observations wells at the site Although the concentiation of petroleum li)diocaibons incieased in mo of the thiee observation \\ells this may be a iesults of desoiption of hydiocaibons from the impacted soil in the smear zone of sample collection techniques 4 0 SOIL V8POR EXTRACTION ' 4.1 PI inciples ' Vapol extraction is a well-kno\\n and \\ell-accepted method of in-situ treatment for soil and has been used successfully at a large number of sites The method works best on volatile hydiocaibons in permeable soil ' Soil vapor extraction systems generally utilize a vacuum blower to volatilize hydrocarbons and draw the vapors into extraction wells screened v ithin the hydrocarbon plume The vapois are drawn from the wells and treated in one of se\eial possible tleatment units, including internal combustion engines, thermal oxidizers, and catalytic oxidizers Because of present hydrocarbon concentrations at the site, initially an internal combustion unit should be chosen for this site C."N l FR}13 Senna. Lio [l CliN'1N R YSBC 7 1