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CLEARWATER C R0 U P I N C Treatment of extracted groundwater is usually mandated by permit prior to elimination into any receiving body of water or public owned treatment system Two groundwater treatment alternatives, air stripping and aqueous-phase GAC, were evaluated Regardless of water treatment type, the likelihood of extracting SPH with groundwater suggests that an oil/water separator will be needed prior to ' treating the water Air stripping removes hydrocarbons from water by maximizing the amount of air in contact with the water The water stream is usually sprayed counter to a stream of "clean" air, and the vastly increased surface area of the water to air promotes volatilization of hydrocarbons The off-gas from the stripper, now laden with hydrocarbons, is subject to treatment like that described for soil vapor extraction before elimination to the atmosphere Depending on water discharge permits the treated water can either be directly discharged to the receiving water or may require final polishing by aqueous-phase GAC Air stripping is a viable groundwater treatment alternative fAqueous-phase GAC treats water in the same way that vapor-phase GAC treats air After the GAC is saturated with hydrocarbons, it must be disposed of and replaced Aqueous-phase GAC has can typically absorb from 5 to 8% of its weight in gasoline hydrocarbons Aqueous-phase GAC is a viable groundwater treatment alternative 732 Air S ar in Air sparging is a process where air is pumped from an above ground compressor into the saturated zone to volatilize dissolved hydrocarbons in the groundwater and provide oxygen to indigenous micro-organisms, thus enabling them to more rapidly metabolize hydrocarbons Air sparging is typically performed in conjunction with soil vapor extraction in order to recover the volatilized hydrocarbons emanating from the saturated zone This technology works best where the soils are relatively permeable and homogenous (i e lacking extensive tight, fine-grained beds) The drawback of this remedial approach is that it has the potential to mound groundwater, and therefore alter local groundwater gradients and flow direction Results of the air sparge test suggest that this 1s a feasible groundwater remediation alternative Sparging used in conjunction with soil vapor extraction is probably more well suited for implementation after the SPH has been removed and is no longer detectable, because sparging in the early phase of remediation may mound the groundwater such that the SPH will actually migrate toward the domestic well Clearwater recommends using air sparging in the latter part of groundwater remediation, only after the SPH has been removed 10 ' D-107,PAR/RAP 20 February 21, 1996