Approximate evaluation of contaminant transport through vertical barriers

Containment of groundwater contamination using physical barriers can be an important element of a subsurface remediation program. This work presents simple analytical tools for predicting the performance of barriers in terms of the steady-state contaminant flux across the barrier, the duration of the transient period following barrier installation, and the time-dependent contaminant concentration distribution within the barrier. The analytical expressions are developed from approximate boundary layer (BL) solutions to the advective-dispersive equation subject to conservative fixed concentration boundary conditions. Critical ranges of important dimensionless quantities are identified for use in barrier performance assessment, for both steady-state and transient conditions. Comparative calculations made with the BL equations and more exact semi-analytical solutions are used to characterize the accuracy and applicability of the BL approach.