Expert Report

Each report is produced by a committee of experts selected by the Academy to address a particular statement of task and is subject to a rigorous, independent peer review; while the reports represent views of the committee, they also are endorsed by the Academy. Learn more on our expert consensus reports.

President Carter's 1980 declaration of a state of emergency at Love Canal, New York recognized that residents' health had been affected by nearby chemical waste sites. The Resource Conservation and Recovery Act, enacted in 1976, had just ushered in a new era of waste management disposal designed to protect the public from harm. It required that modern waste containment systems use "engineered" barriers designed to isolate hazardous and toxic wastes and prevent them from seeping into the environment. These containment systems are now employed at thousands of waste sites around the United States, and their effectiveness must be continually monitored. At the request of the U.S. Environmental Protection Agency, U.S. Department of Energy, National Science Foundation, and U.S. Nuclear Regulatory Commission, this National Research Council report assesses the performance of waste containment barriers to date. Existing data suggest that waste containment systems with liners and covers, when constructed and maintained in accordance with current regulations, are performing well thus far. However, they have not been in existence long enough to assess long-term (postclosure) performance, which may extend for hundreds of years. The report recommends expansion of data collection and reporting, improvement of models, and development of new monitoring techniques to improve future assessments and increase confidence in predictions of barrier system performance.

Key Messages

  • Extrapolations of long-term performance can be made from existing data and models, but they will have high uncertainties until field data are accumulated for longer periods, perhaps 100 years or more.
  • Most engineered waste containment barrier systems that have been designed, constructed, operated, and maintained in accordance with current statutory regulations and requirements have thus far provided environmental protection at or above specified levels.
  • Much data used to predict performance come from laboratory experiments, models, and field-constructed prototype barrier systems (e.g., test pads). Although useful for understanding material properties and behavior, these data are no substitute for performance data collected in the field from operating containment systems.
  • Performance criteria are needed that account for both barrier performance and impacts to public health and safety that extend beyond the barrier system.
  • The optimum time for monitoring varies with the facility, type of waste, climate, and the observed performance. Yet funding is often not available to continue monitoring until the site no longer poses risk to human health and the environment, and no national policy exists to assure that such funding will be available.
  • The performance of many engineered barriers is monitored indirectly, usually through evidence of contaminant migration outside the waste containment system. The absence of direct monitoring data introduces uncertainties about how well the individual elements of the overall containment system are working.