Cap stabilization for reclaimed uranium sites

The reclamation and stabilization of uranium-mill tailings sites requires engineering designs to protect against the disruption of tailings and the potential release of radioactive materials. The reclamation design is to be effective for 200-1000 years. This paper presents recently developed or refined techniques and methodologies used to evaluate uranium-tailings-reclamation plans designed to provide long-term stability against failure modes. Specific cap-design aspects presented include design flood selection, influence of fluvial geomorphology on site stabilization, stable slope prediction, slope stabilization using riprap, and riprap selection relative to rock quality and durability. Design relationships are presented for estimating flow through riprap, sizing riprap, and estimating riprap flow resistance for overtopping conditions. Guidelines for riprap-layer thickness and gradation are presented. A riprap-rating procedure for estimating rock quality and durability is also presented