Basic research strategies for resolving remediation needs in contaminated fractured media

This paper describes a multidisciplinary endeavor to develop and employ basic research strategies for guiding remediation efforts in contaminated fractured subsurface media at the U.S. Department of Energy’s Oak Ridge National Laboratory. It gives a brief overview of research activities spanning the past 15 years that have sought to provide both an improved understanding of and a predictive capability for contaminant transport processes in highly structured, heterogeneous subsurface environments that are complicated by fracture flow and matrix diffusion. Our approach involved a multiscale (cm-to-ha) experimental and numerical endeavor to investigate coupled time-dependent hydrological and geochemical processes that control contaminant migration in unsaturated and saturated soil and rock. Novel tracer techniques and experimental manipulation strategies were applied at laboratory, intermediate, and field scales to unravel the influence of multiple processes on contaminant fate and transport. The basic research strategies have significantly improved our conceptual understanding of time-dependent solute migration in fractured subsurface media. This information has proven useful in decision-making processes regarding selection of effective remedial actions and interpretation of monitoring results after remediation is complete.