Infiltration into and drainage from facilities for the disposal of low-level radioactive wastes is considered the major process by which non-volatile contaminants are transported away from the facilities. The session included 10 papers related to the processes of infiltration and drainage, and to the simulation of flow and transport through the unsaturated zone. The first paper, presented by David Stonestrom, was an overview regarding the application of unsaturated flow theory to infiltration and drainage. Stonestrom posed three basic questions, which are:
- How well do we know the relevant processes affecting flow and transport?
- How well can we measure the parametric functions used to quantify flow and transport?
- How do we treat complexities inherent in field settings?
The other nine papers presented during the session gave some insight to these questions. Topics included: laboratory measurement of unsaturated hydraulic conductivities at low water contents, by John Nimmo; use of environmental tracers to identify preferential flow through fractured media and to quantify drainage, by Edmund Prych and Edwin Weeks; field experiments to evaluate relevant processes affecting infiltration and drainage, by Brian Andraski, Glendon Gee, and Peter Wierenga; and the use of determinist'c and stochastic models for simulating flow and transport through heterogeneous sediments, by Richard Hills, Lynn Gelhar, and Shlomo Neuman.
