Mathematical models are developed for two configurations of migration barrier trenches (sparging curtains). The models include removal by air stripping and by biodegradation, and also include the effects of mass transport kinetics of oxygen and of organic contaminant at the bubble-water interface. Air stripping efficiency is rather sensitive to the design of the aeration trench, as observed previously (10); biodegradation efficiency is relatively insensitive to the design. Comparison of results for trichloroethylene (assumed nonbiodegradable) with results for toluene (assumed biodegradable) indicates that the air flow required for toluene is less than one one-hundredth that required for trichloroethylene. The models should be useful for preliminary screening of this technology, for design work, and for performance evaluation. The importance of utilizing the intrinsic bioremediation capacity of the aquifer between the barrier and the point of compliance is discussed.