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 s imple analytical tools for predicting the performance of barriers in terms of the steady-state contaminant flux across the barrier, the duration of th e transient period following barrier installation, and the time-dependent c ontaminant concentration distribution within the barrier. The analytical ex pressions are developed from approximate boundary layer (BL) solutions to t he advective-dispersive equation subject to conservative fixed concentratio n boundary conditions. Critical ranges of important dimensionless quantitie s 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. (C) 2000 Elsevier Scien ce B.V. All rights reserved.