NEW TECHNOLOGY TO IMPROVE THE UNDERSTANDING OF CONTAMINANT MIGRATION IN FRACTURED GEOLOGICAL SETTINGS

Many military installations and industrial complexes are contaminated with chemicals such as chlorinated solvents, perchlorate, and munitions constituents. Several technologies have been applied to remediate fractured rock sites. It has proven to be extremely difficult to flush contaminants out or to install effective barriers to prevent contaminant migration. Failures of these attempts are largely due to our inability to determine fracture locations, as well as their connectivity in space, hydraulic and transport characteristics of the fractures and the rock matrix, and most importantly the whereabouts of contaminants in these fractured geologic settings. As a consequence, it is critical to develop effective technologies to characterize fracture patterns and their connectivity, hydraulic properties of fractures and the rock matrix, as well as to understand the mass transfer mechanism, and to monitor the effectiveness of remediation technologies in fractured terrains.

In this study, we demonstrate that the widely adopted mass transfer concept is merely a consequence of our inability to characterize fractures and matrix heterogeneity at a variety of scales. While this concept is practical, when applied to remediate a field site, it fails to produce the level of resolution required. We therefore propose a new technology that permits high-resolution “imaging” of fractured rocks and contaminant distribution. The new technology is based on the stochastic fusion of geophysical electromagnetic tomography and recently developed hydraulic/tracer tomography. The development of this information fusion technology is on-going for imaging the heterogeneity distribution of flow/transport parameters and DNAPL distributions in contaminant source zones situated in porous media. Preliminary results are very promising.