Groundwater Cleanup by In-Situ Sparging. VII. Volatile Organic Compounds Concentration Rebound Caused by Diffusion after Shutdown

Abstract

Abstract The sparging of aquifers contaminated with volatile organic compounds (VOCs) is examined by means of a mathematical model which includes the kinetics of solution of nonaqueous phase liquid (NAPL) droplets and of diffusion of VOCs from porous layers of low permeability. The well configuration is that of a single vertical well screened only near the bottom. The dependence of cleanup rates on model parameters (well depth, air flow rate, NAPL droplet diameter, thickness of low-permeability structures, etc.) is reported. The rebound of VOC concentration in the mobile aqueous phase after the sparging well is shut down is examined. Model runs require only a few minutes of computer time on currently available microcomputers. ∗Permanent address: Department of Chemistry, Box 1822 Sta. B, Vanderbilt University, Nashville, Tennessee 37235, USA.