Abstract:

Giant Mine, an abandoned gold mine located in the traditional territory of the Yellowknives Dene and North Slave Metis and within Canada’s Northwest Territories, operated from 1940’s to 1990’s. The Governments of Canada and the Northwest Territories assumed responsibility to remediate this site in 2004 following bankruptcy of the final owner. Consisting of 8 open pits and extensive underground workings significantly contaminated with arsenic, water management at Giant Mine is a complex endeavour.

A critical component of the Giant Mine Remediation Project (GMRP) is the development of the Water Treatment Plant (WTP), to treat the arsenic-contaminated minewater from a median concentration of 28 mg/L to within the CCME (Canadian standard) for drinking water quality of 0.01 mg/L. Drawing minewater from two deep wells, the WTP is designed to maintain a minewater elevation in the underground below the elevation of the frozen shell that is being implemented to immobilize the 237,000 tonnes of arsenic trioxide dust stored in underground stopes and chambers.

Construction of the WTP plant extends well beyond typical scope, including arsenic-contaminated soils removal, deep well drilling, blasting and crushing of rock for reuse, construction of a 1.4 km outfall pipeline and marine outfall structure for discharge to Yellowknife Bay. In an effort to minimize GHG emissions from WTP operations, biomass was selected as the heat source for the WTP structure.

This presentation is meant as an overview of the challenges of water management, WTP development, procurement and construction in the unique setting of Giant Mine, Canada’s North and complex regulatory framework. Construction is underway and scheduled for completion in 2026.

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Patrick Schmidt

Biography