Concepts for and experience gained from tailings capping systems in the uranium mill tailings remedial action project, USA

The Uranium Mill Tailings Remedial Action (UMTRA) Project designed and constructed disposal cells at 19 sites across the United States. Design philosophy of cover systems used for long-term containment of hazardous and low-level radioactive wastes has undergone significant changes since the initial designs were conceptualized following passage of the Uranium Mill Tailings Radiation Control Act (UMTRCA) in 1978. Regulatory framework established design-based standards for the project, and the UMTRA Project designed covers to control a suite of contaminant-release processes. Because of regulatory changes and applications of lessons learned, cover designs for UMTRA Project disposal cells evolved to reflect changes in U.S. Environmental Protection Agency (EPA) standards and changes in politics, economics, and the state of technology during the 20-year life of the UMTRA Project. Stewardship responsibilities for UMTRA Project studies of the performance of existing UMTRA Project covers to help improve the design process for the next generation of covers. (orig.)