Risk Assessment — Remediation

Abstract

The purpose of this chapter is to provide examples of diffusion limited contaminant transport for some cases of practical interest. The length of the mass transfer zones is briefly introduced which can be used for risk assessment, e.g. to distinguish maximum contaminant concentrations (equilibrium, e.g. dissolution from residual phase) from maximum contaminant flux (non-equilibrium, e.g. due to slow desorption) into groundwater. Transport of volatile compounds across the capillary fringe (both directions) is treated analogously to pool dissolution (semiinfinite diffusion). Typical dissolution time scales are discussed, together with desorption processes desorption processes, limiting aquifer and soil remediation. Finally a comparison of advective and diffusive solute transport is provided.