Numerical Simulation of In Situ Air-Sparging

A model for predicting air-flow patterns generated during the remediation technology of insitu air-sparging (IAS) is presented. The model assumes that the groundwater is initially hydrostatic and that the pressure of air in the plume generated by IAS is spatially, but not temporally, constant. The air pressure in the propagating plume is calculated using the ideal gas law, while the pore pressure in the groundwater adjacent to the plume is calculated using the Young-Laplace equation. Groundwater flow induced by excess pore water pressure is described by Darcy's law, and the expansion or contraction of the air plume boundaries is determined by the magnitude and direction of this flow. The model uses parameters, such as soil porosity and intrinsic permeability that can be determined from standard measurements at field sites. By dividing the model domain into cells of small, finite size, macroscopic the heterogeneity of soil properties can be accounted for. The paper describes the model, discusses the assumptions made in its development, compares the model predictions with experimental results from laboratory tests, and summarizes plans for its further refinement.