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3 The Giant Mine site, located just outside Yellowknife, Northwest Territories, is the focus of one of the most ambitious and technically complex remediation efforts in Canadian history. The Giant Mine Remediation Project has transitioned from early-stage planning to fullscale remediation, advancing environmental goals while fostering strong Indigenous and community partnerships, the project is an example of how long-term vision, technical excellence, and inclusive leadership can come together to address the legacy of industrial development. MAJOR MILESTONES ACHIEVED Since 2022, the remediation team has made notable headway across a range of priorities. These include deconstructing the former townsite and key industrial buildings, completing the closure of the underground mine, and backfilling near-surface stopes. The team has also launched revegetation test plots and begun construction of a new water treatment plant, scheduled to be operational by 2026.
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5 “This work is happening in a phased, carefully sequenced manner,” says Natalie Plato, Project Director. “The underground is closed, and we’ve shifted focus to above-ground decontamination and demolition. The water treatment plant is now the key project on site.” ADDRESSING THE ARSENIC CHALLENGE WITH INNOVATIVE FREEZE TECHNOLOGY Central to the remediation is the long-term containment of 237,000 tonnes of arsenic trioxide stored underground. The solution lies in passive freeze technology, utilizing thermosyphons—metal tubes filled with pressurized carbon dioxide—to draw heat from the ground. This cycle requires no external energy and maintains underground temperatures at or below -5°C. “Once the freeze is in place, the arsenic trioxide will remain in a stable, frozen state indefinitely,” explains Plato. “And to ensure it stays that way, we’ve installed thermistors to monitor temperatures and can intervene if thawing ever becomes a risk.” THE CHALLENGE OF COMPLEXITY: COORDINATION AND COMMUNICATION The scale and complexity of the project require constant coordination across numerous federal departments, contractor teams, and community stakeholders. Plato emphasizes that beyond Building what matters to enable future generations to thrive. Aecon is proud to contribute to the wider remediation project at Giant Mine, working collaboratively with Crown-Indigenous Relations and Northern Affairs Canada, Parsons Inc. and local Indigenous Communities to help protect community health and support long-term environmental safety in Yellowknife.
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7 technical logistics, communication is among the most demanding aspects of project leadership. “Managing this project involves daily collaboration between the Government of Canada, contractors, regulators, and Indigenous and local stakeholders,” she says. “We place a high priority on listening, informing, and engaging, especially with the Yellowknives Dene First Nation and the people of Ndilǫ, Dettah, and Yellowknife.” Two advisory bodies—the Giant Mine Advisory Committee and the Giant Mine Working Group—help channel feedback into planning and implementation. These bodies include representation from government agencies, Indigenous governments, NGOs, and municipal leaders. STRENGTHENING INDIGENOUS PARTNERSHIPS Trust-building has been key. Since the establishment of the project’s Environmental Agreement, engagement with the Yellowknives Dene First Nation, the North Slave Métis Alliance, and the Tłı̨ chǫ Government has deepened. The Project team actively incorporates Indigenous feedback and has funded Traditional Knowledge studies to guide remediation and land-use decisions. Natalie Plato, Project Director
8 “Relationships have improved because of meaningful consultation and growing participation,” says Plato. “We’re fortunate to work with partners who are engaged and dedicated.” DRIVING LOCAL ECONOMIC DEVELOPMENT The Giant Mine Remediation Project has also emerged as a powerful economic catalyst for the region. Through a dedicated socio-economic strategy, the project is generating employment, building capacity, and awarding contracts to northern and Indigenous businesses. Key agreements signed in 2023 and 2025—such as the Yellowknives Dene First Nation’s Procurement Framework and Community Benefits Agreements, and similar agreements with the Tłı̨ chǫ Government and North Slave Métis Alliance—are ensuring that the benefits of remediation are shared locally. “There are both direct and indirect benefits,” Plato says. “From training programs to procurement contracts, to local spending from project workers…it all adds up to long-term economic growth.” ENVIRONMENTAL MONITORING FOR DECADES TO COME The commitment to environmental stewardship goes beyond active remediation. Long-term site monitoring is underway, including assessments
9 of water and air quality, vegetation, and wildlife. These efforts feed into the Long-term Monitoring Program (LTMP), which will track progress against environmental goals and adapt based on results. A key part of that future is the Perpetual Care Plan, designed to ensure the site is safely managed for generations. It will encompass records management, knowledge transfer, funding mechanisms, and risk scenario planning. “The first draft of the Perpetual Care Plan will be ready in 2027,” says Plato. “It’s a living document built collaboratively with our partners, and it will carry the project into the next phase of stewardship.” RECONCILING WITH THE PAST For many, remediation is more than a technical challenge; it’s also a matter of justice. The Giant Mine’s legacy includes deep harm to the Yellowknives Dene First Nation. Plato acknowledges this reality and points to recent steps by the federal government to engage directly on legacy issues. In March 2025, Murray Rankin was appointed as the Minister’s Special Representative to examine the mine’s historical impacts and present resolution options. His independent report is expected in 2026. “This is an important and necessary conversation,” says Plato. “The remediation is one piece of a
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11 broader process to understand and address the legacy of the mine.” PREPARING FOR LONG-TERM SITE MANAGEMENT Looking ahead to the transition from construction to long-term care, the focus is on overlap, knowledge transfer, and community involvement. Plato says ensuring continuity is critical. “The success of the long-term phase will hinge on engagement and planning. We need a smooth handoff from the current construction management team to the group responsible for long-term monitoring, particularly for systems like the water treatment plant.” A MODEL FOR FUTURE REMEDIATION PROJECTS As the Giant Mine Remediation Project progresses in implementing the Closure and Reclamation Plan, it offers a clear lesson: major remediation efforts can be driven by both scientific excellence and meaningful collaboration. With implementation underway and long-term monitoring on the horizon, the project is well-positioned to become a national benchmark for environmental remediation, reconciliation, and sustainable development in the North. For more information, please visit www.giantminerp.ca
As seen in BusinessEliteCanada.com www.giantminerp.ca
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