Improvement of Approaches to Waste Containment System Development, Management, and Evaluation

Abstract

Waste-containment sites number in the hundreds of thousands throughout the world as a result of past and continuing industrial, municipal, and military activities. Within the United States alone, recent records of the United States Environmental Protection Agency USEPA indicate the existence of more than 200,000 contaminated sites, a large fraction of which involve or need waste containment. In addition to contaminated sites and facilities, a large waste-generation inventory comprises billions of metric tons of metal mining and processing wastes, oil and gas processing wastes, industrial wastes, municipal wastes, and solid wastes from electric power generation stations. At the Hanford site, which had been a plutonium production site for 50 years, approximately 7,600 cubic meters of actinides, as well as 1.2 million cubic meters of low-level radioactive wastes, are buried. It is not feasible to chemically or biologically clean up all contaminated sites because of excessive costs including opportunity costs . Furthermore, the complexities of both the subsurface geohydrology of contaminated sites and the lack of field-scale cleanup technologies that can apply mechanisms proved at the bench scale for some persistent contaminants to field scale make it infeasible to implement cleanup programs as the sole means of managing contaminated sites. With respect to solid waste management, recycling has not kept pace with generation rates. Consequently, waste storage in containment systems will remain as a waste-management option for the foreseeable future. Among these systems are landfills, waste piles, covers and liners, grout curtains, slurry walls, reactive walls and beds, concrete tombs, and radioactive waste repositories. For these systems, the primary design function is minimizing the rates of contaminant release into the environment for service lives that range from about 10 years to 1,000 years. The performance of this function requires that the structural integrity of these systems be maintained for very long time periods. Considering the high uncertainties associated with system performance over very long time spans within which transient stressors such as floods and earthquakes may affect some facilities, the challenge is to develop effective ap-