Location | Yellowknife, Northwest Territories
Sector | Energy, Resources, Industry
Market | Mining
Project Delivery Method: Remediation Plan
Discipline | Environmental, Civil
Giant Mine, a now abandoned gold mine located on the Ingraham Trail just outside of Yellowknife, Northwest Territories, which entered production in 1948 ceased operations in 2004 to begin a 10-year remediation project began at the mine to contain the arsenic trioxide waste.
Williams Engineering Canada (WEC) partnered with Parsons Canada to remediate the Roaster Complex at Giant Mine, WEC’s role during the project was to provide the quality air monitoring survey inside the buildings during decontamination work and outside the buildings for perimeter monitoring. We believe that decommissioning a mine should not only focus on preventing or mitigating environmental degradation and protecting public health and safety, but it should also provide alternative options to conserve the land for future generations and use.
While in operation, Giant Mine led to the production of seven million ounces of gold and resulted in one of the longest continuous gold mining operations in Canadian mining history. However, mining operations over five decades created a massive environmental liability.
Gold at Giant Mine was found in the specific mineral: arsenopyrite ore. To release the gold, the ore had to be roasted at extremely high temperatures. Unfortunately, this roasting process also released arsenic rich gas, a highly toxic by-product. About 237,000 tonnes of arsenic trioxide dust is stored in 15 underground chambers located in solid rock between 80 to 250 feet below the surface of the mine site. This dust is water soluble and contains approximately 60 per cent arsenic. The site’s 2,300 acre footprint includes eight open pits, four tailing ponds, 325,000 cubic metres of contaminated soils, and approximately 100 buildings including a roaster/bag house complex that is highly contaminated with arsenic and fibrous asbestos.
The project was completed in 2014. The Giant Mine Remediation project was a unique and complex opportunity that underwent extensive expert and public review. The robust and diligent plan supported the Government of Canada’s commitment to ensuring the health and safety of the public and protection of the environment.