A mathematical model is presented for the removal of dense nonaqueous phase liquid (DNAPL) droplets in an aquifer by air sparging with a horizontal slotted pipe. Diffusion transport of volatile organic compounds (VOCs) from the DNAPL droplets to the aqueous phase is assumed to take place through a thick stagnant water layer in the porous medium to a mobile aqueous phase. Transport of VOC from the aqueous phase into the gas phase is modeled by means of a lumped parameter approach. The air-induced circulation of water in the vicinity of the air injection pipe is modeled by means of the method of images. The effects of the various model parameters on the rate of VOC removal are explored both for cases in which DNAPL is present and in which contaminant is present only as VOC dissolved in the aqueous phase.