After undergoing construction for three years, a new water treatment facility is scheduled to be operational at the Giant Mine cleanup site in spring 2027.
During a recent site inspection, representatives from the Giant Mine Remediation Project announced that the upcoming plant will replace an outdated treatment system that has been in use since the 1980s. This new facility will be responsible for treating both surface and groundwater at the site to eliminate arsenic and other potentially hazardous substances originating from the former gold mine before releasing the water into Yellowknife Bay.
The design manager of the project, Patrick Schmidt, detailed that the system is designed to lower arsenic concentrations in the water to the Health Canada limit of 10 parts per billion. In comparison, the previous water permits allowed levels as high as 300 parts per billion of arsenic to be discharged into Baker Creek, exceeding current drinking water standards. With the direct discharge into Yellowknife Bay, the new treatment plant is expected to ensure compliance with stringent regulations.
Schmidt emphasized the effectiveness of the water treatment process, highlighting the inclusion of an additional stage for removing metals, specifically utilizing arsenic adsorption media to achieve drinking water quality standards. Real-time sensors will be deployed to monitor arsenic levels continuously and prevent the release of untreated water. Monthly surveillance reports will be available online for public scrutiny, along with an annual summary detailing the arsenic levels in the discharged water.
Deputy Director Natalie Plato acknowledged that there is ongoing work to clean up the site, with the current cleanup phase, initiated in 2021, projected to conclude by 2038 within the allocated $4.38 billion budget. Plato expressed optimism about the progress made so far and identified the completion of the water treatment plant as a significant milestone for the overall project.
Officials also provided updates on the demolition progress of the mine’s mill building, expected to be finished by November. The most critical aspect of the project involves securely containing 237,000 tonnes of arsenic trioxide until a permanent solution is implemented. Testing of a novel freezing method using thermosyphons to solidify the arsenic trioxide in underground chambers has shown promise and will be expanded across all chambers.
Graeme Clinton, chair of the Giant Mine Oversight Board, praised the advanced capabilities of the new water treatment plant in meeting regulatory standards. He commended the innovative process employed to eliminate arsenic from the water and the facility’s compliance with updated regulations. Clinton emphasized the board’s commitment to finding a lasting resolution to the arsenic issue and exploring methods to convert arsenic into glass or metallic form for potential applications like electronics manufacturing.