MIGRATION OF POLLUTANTS IN GROUNDWATER .6. FLUSHING OF DNAPL DROPLETSGANGLIA

Models for describing the flushing of DNAPL from contaminated aquifers are developed, and the dependence of the calculated cleanup times on the model parameters is explored. Diffusion transport from isolated DN APL droplets, from low-permeability porous spherical domains containin g distributed DNAPL droplets, and from low-permeability porous planar lamellae containing distributed DNAPL is analyzed, and the resulting e xpressions then coupled with the equations for advective transport of dissolved VOC by means of natural uniform flow and a system of injecti on and recovery wells generating a two-dimensional flow field. The mod els are readily run on currently available microcomputers. The results of computations with the models are consistent with the severe tailin g and slow rates of remediation which are generally observed when DNAP Ls are removed by flushing.