Remediation of Historic Dump #2 at Chalk River Laboratories

Abstract

Dump #2 is a 0.2 hectare (3,400 m³volume) landfill at Chalk River Laboratories (CRL) on the Ottawa River shoreline. In operation between 1960 and 1972, the site was used for the then-accepted practice of open burning of non-radioactive trash. Over the course of the landfill’s operation, and its use as an electrical equipment storage yard, some contamination incidents have occurred. Characterization studies have revealed local hotspots of soil radiological contamination (Cs-137 and refined natural U) and chemical contamination (heavy metals typical of ash). As Uranium levels at hotspots are in excess of the CNSC published unconditional clearance level for soil, the current long-term remediation strategy is to excavate the landfill and transfer the contents to a suitable waste disposal facility. In the interim, the plan is to stabilize the slope and protect it from potential damage in the event of extreme flooding. This will be accomplished by treating eroded channels and placing a rock revetment below the 100-year flood line. Deciding the proper final remediation strategy is a challenge due to uncertainty in when disposal facilities will be available, uncertainty regarding hazards in the landfill, differing perceptions of risk, and end-state criteria still under development. Collaboration with internal groups at CRL and benchmarking to other site clean-up agreements are being used to establish the framework for remedial measures that are in keeping with the (low) level of risk.