Simulation of subsurface processes using very-large physical models. Selected Research Activities Diffusive Contaminant Transport in Fine Grained Media. Subsurface burial of hazardous wastes is an important component of most current waste disposal strategies. At many facilities, clay liners are used to contain the wastes by eliminating advective transport. If successful, transport in the liner will be molecular diffusion limited.
Diffusion can, however, transport large quantities of hazardous materials out of the disposal site.
The rate at which contaminants move into and through the liner can be predicted using Fickian diffusion models, if the effective diffusion coefficient of the contaminant of interest is known. These may be estimated in the laboratory using intact pieces of liner material, or they may be observed directly at existing waste disposal sites. The latter approach is being used in a joint research project with the University of Waterloo at a site in southwestern Ontario. Core samples of clay liner were collected from immediately below the waste. The cores were sectioned and contaminant concentrations determined in each section.