Remediation of radioactive and mixed waste located in the U.S. Department of Energy (DOE) nuclear weapons complex will require increased use of physical barriers to prevent the spreading of contaminants during interim periods of cleanup and the migration of contaminants left behind upon completion of the cleanup.
To raise the level of awareness of available technologies and to provide information on the current knowledge of barrier performance through technology development and actual installation, the Committee on Remediation of Buried and Tank Wastes and representatives of the DOE Office of Environmental Restoration organized a 1-day workshop on engineered barriers. Participants in this workshop included government researchers and contractors, as well as barrier designers and builders from private industries.
This summary report is a synthesis of the oral discussions at the workshop. It does not express opinions of the committee. The committee issued a report recently, entitled The Potential Role of Containment-in-Place in an Integrated Approach to the Hanford Reservation Site Environmental Remediation (National Research Council, 1996), on the potential use of barriers at a DOE site.
Not all waste problems can be solved by excavating and treating the wastes. Proper use of effective barrier technologies can provide both interim containment while more permanent remedial technologies are being developed, and longer-term isolation of radioactive and hazardous contaminants remaining after remediation. Consequently, barriers such as surface caps and subsurface vertical and horizontal barriers will be needed as important components of remediation strategies.
Several themes emerged during the discussions at the workshop:
The importance of employing proper installation techniques and quality control measures, especially during construction, including using contractors with demonstrated experience and skill.
The need for knowledge concerning effective lifetimes of selected barrier materials and resultant barrier systems.
The importance of periodic inspection, maintenance, and monitoring of containment barriers.
The current dearth of barrier performance monitoring data.
The advantages of using barriers in combination with pump-and-treat approaches.
The importance of compiling data on both successful and unsuccessful barrier installations.
Although these issues were not explored fully during the workshop, they will serve as good starting points for future discussion on containment technology. Appendix D to this summary report