Planning the remediation of Giant Mine

The Giant Mine Remediation Plan is under revision to address measures identified in the Report of Environmental Assessment.

What is the status of the site and the remediation plan?

The Giant Mine site is currently under care and maintenance to manage ongoing risks; however, full remediation is necessary to fully address these risks. The site was home to more than 50 years of gold mining and ore processing. Arsenic trioxide stored underground requires effective management to protect human health and safety and the environment. The remediation plan will outline how this will be done and describe general site clean-up activities on the surface of the mine site.

In 2007, the Giant Mine Remediation Project team submitted a remediation plan to the Mackenzie Valley Land and Water Board as part of a Water License application. The plan incorporated industry-best practices and technologies. It was subject to extensive review by an Independent Peer Review Panel, as well as by experts in other government departments.

The remediation plan submitted to the Board addressed all aspects of the underground and surface clean-up of the mine. This plan was then referred to Environmental Assessment by the City of Yellowknife, which was completed in 2014. The remediation plan is currently undergoing revision to address measures identified in the Report of Environmental Assessment. Once complete, the Project team will re-submit revised plan (called the Closure and Reclamation Plan) to the Mackenzie Valley Land and Water Board.

The Project team must submit this revised Closure and Reclamation plan to apply for a Water Licence (planned for 2019) as part of the regulatory process before remediation can proceed. This includes getting approval for our updated plan before we can begin doing the work. The remediation of Giant Mine will comply with all applicable legislation. It is anticipated to begin in 2020 - 2021.

For more information, you can call the project office at (867) 669-2426 or email giantmine@aandc.gc.ca.

What will the remediation plan for the site include?

The Giant Mine remediation is the blueprint for cleaning up the site to ensure human health and safety and protection of the environment. It covers the clean-up of the entire mine site, both surface and underground aspects. The initial plan received thorough review by technical advisors and subject matter experts to ensure it addresses all the issues associated with cleaning up the mine site. The new plan will also undergo a thorough review. The plan will include consideration of potential future uses of the site (after the remediation is complete), but the Government of the Northwest Territories and the City of Yellowknife will make the final decisions on any future land uses.

The remediation plan for the site will address:

The original remediation plan for the Giant Mine site was drafted after years of site investigations, research, and extensive consultation with the public and with the Independent Peer Review Panel. The updated plan will also undergo extensive public consultation and review. The plan contains five distinct but interconnected components:

The surface remediation may take up to 10 years to complete. The complete freezing of the underground arsenic trioxide chambers and surrounding areas may take up to 15 years. Most of the arsenic trioxide will stay safely sealed in the underground chambers, frozen behind concrete bulkheads.

The goal of the remediation is to minimize public health and safety issues, as well as environmental concerns. The Project team will work to return the site as closely as possible to the natural landscape for the Yellowknife area. However, some areas will remain under active management and monitoring. New and relevant information regarding this project will also continue to be considered and evaluated.

Will be final remediation plan be safe?

The long-term remediation of Giant Mine will comply with all applicable legislation. The Closure and Reclamation Plan (also referred to as the Remediation Plan) will include cleanup methods successfully used at other contaminated sites across North America and worldwide. The Project team will adopt safety measures developed for other complex and challenging projects in North America. In addition, managing the arsenic trioxide dust in place (where it is currently stored) will avoid the health and safety to workers who would have to move or handle the toxic material in the "take out" option.

Indigenous and Northern Affairs Canada has spent over 10 years assessing Giant Mine to gather the necessary information to develop the Closure and Reclamation plan. The plan for the long-term management of the underground arsenic trioxide dust was presented to the public and discussed at two separate workshops in 2003. Options for the surface remediation were presented to the public through the Surface Design Engagement process in 2015 and 2016. Input received from the public will be incorporated into the final Giant Mine Closure and Reclamation plan, expected to be complete by 2019. The Project team will continue to engage with the public before finalizing the plan.

The Closure and Reclamation Plan will address all aspects of the underground and surface cleanup of the mine. It will incorporate industry-best practices and technologies. It will also be subject to extensive review by an Independent Peer Review Panel, as well as by experts in other government departments and by members of the public. As well, it will be updated to reflect the 26 measures of the Report of Environmental Assessment. Once updated, it will undergo review by the Mackenzie Valley Land and Water Board as part of the regulatory process.

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