Remediation of a former low-level landfill (Waste Management Area C) at Chalk River Laboratories

Waste Management Area C is a 4-hectare landfill-type facility at Chalk River Laboratories that operated for 43 years, receiving a large variety of low-level radioactive wastes and nonradioactive wastes. Since these wastes were emplaced directly into sand trenches and pits, infiltration of precipitation over time led to the development of groundwater plumes that carried primarily tritium to nearby swamps. An experimental polyethylene cover installed in 1983 over an area of filled sand trenches led to a sharp reduction in groundwater tritium down gradient of the area. In 2010, detailed design was therefore undertaken for a multi-layered low-permeability 100-year engineered cover over the entire facility. Close collaboration was needed between the owner, the designer, and the construction contractor to overcome difficulties during installation in 2013. This paper focuses on the technical challenges in mitigating hazards at the closed facility, and the collaboration that was needed to achieve this mitigation. (author)