An Overview of Chalk River Laboratories’ Experience in Addressing Legacy Site Liability

• Tuesday, September 9, 2025

Recording

Presentation Slides (PDF)

Seminar Abstract

This seminar will offer a technical overview of current methodologies, lessons learned, and ongoing efforts to address environmental liability at legacy waste management areas within a regulated nuclear environment.

The Chalk River Laboratories site, located in Chalk River, Ontario (Canada), includes several complex legacy landfills that present significant challenges for environmental characterization and remediation. These sites, affected by historical nuclear and non-nuclear waste disposal practices, require integrated, science-based approaches involving radiological and conventional contaminant assessment, geotechnical investigation, excess soil management, and risk-informed decision-making. Characterization strategies are designed to support regulatory compliance, long-term site stewardship, and alignment with evolving environmental protection standards.

Attendees will gain insights into the following topics:

• The evolution of internal programs and processes that integrate environmental considerations across decommissioning and site revitalization activities.
• The assessment and management of conventional contaminants using environmental site assessment tools, human health and ecological risk frameworks, and remediation planning.
• The development and application of site/media-specific scaling factors utilizing data from easier-to-measure radionuclides to estimate the relative quantity of difficult-to-measure isotopes—an approach adapted for the complexities of legacy environmental contamination. These data can then be used to estimate the radiological contaminants of concern within a site, informing risk assessment and remediation planning.
• The benefits as well as the practical and regulatory challenges of adopting non-nuclear regulations to manage excess soil on an active nuclear site. The Soil Management Process was introduced last year and provides a flexible framework for a variety of projects and jobs to implement sustainable and practical solutions to reduce, reuse, and divert excess soil from waste streams. This can help keep project schedules on track and eliminate unexpected costs.

Presenters

• Lucia Valente is a Land Use Program Officer, working at Canadian Nuclear Laboratories (CNL) for the past 6 years. She has been a part of the creation and roll out of the Cleanup Function which houses the Land Use, Decommissioning, and Environmental Remediation programs at CNL. Lucia is passionate about ensuring environmental, decommissioning, and land use processes are reflective of best practices as well as ensure regulatory compliance. 
• Ariel Nunez Garcia is a licensed Professional Engineer (P. Eng.) in the province of Ontario and currently works as an Environmental Remediation Specialist at CNL. He is responsible for planning and executing remediation projects at the CRL site. Prior to joining CNL, he conducted research at Western University and Queen’s University, focusing on in-situ chemical remediation (ISCR) treatments and intermediate-scale testing of in-situ thermal remediation technologies.
• Stephanie Thomson is an Environmental Remediation Specialist at CNL, focusing on radiologically contamination lands. She holds an MSc in Geochronology and has worked for CNL for 15 years.  Prior to her role within Environmental Remediation, Stephanie spent several years as a Research Chemist and Waste Characterization Specialist.
• Sonja Lindberg is an Environmental Specialist with the Cleanup Function at CNL. Sonja is passionate about practical and holistic approaches to ensuring compliance and sustainability in the clean up of contaminated sites. She earned her Geoscientist-in-Training status in Feb. 2024.

Facilitators

• Nik Qafoku, PhD, is Deputy Director of the Center for the Remediation of Complex Sites (RemPlex) and a laboratory fellow. He joined Pacific Northwest National Laboratory in 2000 as a postdoctoral researcher, rising through his career to his current role as a laboratory fellow at in the Environmental Subsurface Science Group. His PhD in environmental soil chemistry is from the University of Georgia.
• David Yuke is a Project Leader at CNL, with over 18 years of environmental site assessment and remediation projects, 10 of which have been in the nuclear industry at CNL Chalk River Laboratories. He is responsible for managing the planning, site assessment, and remediation of the radioactive waste management areas at Chalk River Laboratories. David holds a BS in Environmental Science from Trent University and is also certified as a Project Management Professional (PMP).