Giant Mine

The Giant Mine site is located on the Ingraham Trail, 5 km north of Yellowknife, NT. Between 1948 and 2004, Giant Mine was a major economic driver for Yellowknife and the Northwest Territories. When the mine closed, attention focused on the environmental issues left behind, notably 237,000 tonnes of arsenic trioxide stored in underground chambers. In 2018, Parson’s Inc. was contracted by Public Services and Procurement Canada to take over management of the mine’s care and maintenance program.

Water Treatment Plant (2023-Present)

Commenced: 2023
Completed: In Progress
Client: Public Services and Procurement Canada (Government of Canada)

In May 2023, Nuna Deton’Cho Contracting Joint Venture (NDCCJV), a partnership with Det’on Cho Management LP, was awarded the contract for the earthworks scope of the water treatment plant project at the Giant Mine site. NDCCJV’s contract commenced June 2023 and is expected to conclude in late 2024. Our scope of work includes:

Excavation of arsenic contaminated soils.
Construction of two wastewater ponds.
Construction of an outfall corridor including shear wall blasting and wall control in a 20 m deep box cut.
Construction of site pads and roads.
Installation of pre-cast manholes, HDPE piping, and ductile iron piping watermain systems.

The water treatment plan is one step among many towards reclamation of the Giant Mine site.

Surface Care & Maintenance (2018-2024)

Commenced: 2018
Completed: 2024

Deton’Cho / Nuna Joint Venture provided services to the Mine Manager including electrical, mechanical, and civil maintenance, site-wide road maintenance, repair of all surface infrastructure, and underground electrical maintenance and repair. The Surface Care and Maintenance contract also included surface environmental protection, surface and underground water management and monitoring, waste management, site-specific health and safety requirements, drilling support, and select demolition work.

Care & Maintenance (2005-2018)

Commenced: 2005
Completed: 2018

In 2005, Deton’Cho / Nuna Joint Venture (DCNJV) was contracted by the Government of Canada to provide care and maintenance at the Giant Mine site. DCNJV’s scope included: maintenance of site facilities, equipment, underground access, and hoisting and pumping equipment; site security; bulk fuel storage demolition; select building demolition; pipe works upgrade; surface water management improvements; and operation of the effluent treatment plant.

Freeze Optimization Study (2011-2013)

Commenced: 2011
Completed: 2013

Under the Giant Mine Care & Maintenance contract with the Government of Canada, Deton’Cho / Nuna Joint Venture provided construction services to support a trial project designed to optimize methods of freezing the underground arsenic storage chambers. Work included: surface drilling by a variety of methods (mud rotary, coring, and down hole hammer) and installation of piping for a mechanical freezing system; instrumentation installations; underground development required for horizontal drilling and freeze pipe installation; surface civil works and site grading; and bulkhead construction.

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