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05 May 1997 <br /> AGE-NC Project No 95-0173 <br />' Page 21 of 29 <br />' sparging well Sandy soil types tend to produce a larger radius of influence, clayey soil types tend <br /> to produce a more limited radius of influence <br /> Unless infection wells are properly located, channeling of air flow streams may occur and <br /> contamination pockets may be bypassed This problem is more common where fine-grained strata <br /> having low permeability are interbedded with coarse-grained strata in the saturated zone Air flow <br />' is retarded within fine-grained strata, and hydrocarbon recovery is poor <br /> Use of this technology would require the installation of air infection points, and screened intervals <br />' located approximately five feet below the water The IAS system must be combined with vapor <br /> extraction to contain vapor stripped from the ground water The installation of extraction wells <br /> would also be required <br />' 8 1 3 Monitoring Activities <br /> One of the potential problems associated with air sparging is lateral spreading of the contaminant <br />'. plume This can be caused by either mounding of ground water above injection points or lateral air <br /> flow away from sparging wells To detect this problem, ground water elevations in monitoring wells <br /> and extraction wells (if appropriate) should be monitored on a monthly basis, at the minimum, to <br /> tdetect mounding and the presence of organic vapor <br />' S 1 4 Feasibility <br /> In-situ air sparging of dissolved hydrocarbons in ground water at the site has a high feasibility at the <br /> site Remediation of ground water at the site would require a moderate number of injection and <br /> extraction points An intensive piping network for infection and extraction must also be installed <br /> Air infection and extraction rates must be balanced to prevent the forced migration of contaminants <br />' However, air sparging has proven itself a very effective method for remediation of soil in the smear <br /> zone impacted by volatile petroleum hydrocarbons <br /> a RacLarl nn rl�fn nnllnntari Ai%—"g on TAC I,1AY r.1 IM taut If the .Ciite d-^nditin"S nt Tina <br /> V Vi♦ µµLµ LWLA rL Lir µCil Al}5 µ}l 1/LV a�rKJl Vlll L� FA4W& L� OL iJ�+1 Wy vu u. , <br /> site are conducive for air sparging activity The IAS method has been proven to be effective in many <br /> different soil types and at sites in California with varied ground water depths <br /> n11 In the Catllrnt'-d -Ynn- hPt't%7PP11 117 ITtIT-71►7P fPPt nnrl CIVtV-TPPt aC a rPlat3vP}v blah CAn(j rnntPYlt <br />' potentially making IAS effective for this zone Figures 3 and 4 depict cross sections, showing <br /> subsurface soil types at the site An IAS pilot test was performed at the site, results of the pilot test <br /> • are summarized in Section 4 0 <br /> Advanced GeoEnr ironmental,Ine <br />