TTHENAAGO/NAHANNI BUTTE
At least two storage sites at Cantung Mine west of Nahanni Butte are out of service and contaminated soil was removed from at least four locations after a federal inspection dug up a slew of leaks, spills and equipment issues during a recent visit to the mine site.

Quarry water flowing into the Flat River created a noticeable plume, according to inspectors. - photo courtesy of Indigenous and Northern Affairs Canada

On May 10, Indigenous and Northern Affairs Canada inspectors Tim Morton and Devin Penney were on-site to ensure workers were complying with the site's water licence and land-use permits. The mine is currently in a care and maintenance period, meaning there are no mining operations ongoing and on-site activity is limited to water treatment, environmental risk minimization and site maintenance.

Failure to comply with conditions

On May 12, Morton notified North American Tungsten they were in contravention of two conditions to their land-use permit and management plan. Those conditions included installing erosion control structures and immediately reporting spills.

The company was ordered to immediately put up erosion and sediment controls. Those orders came with a stiff warning from Morton that fines of up to $100,000 can apply to anyone convicted of contravening sections of the Mackenzie Valley Resource Management Act.

During their inspection, Morton and Penney found at least three areas where contaminants such as diesel and berm water were leaking into the ground, and multiple tears in lining used to contain potential spills.

Additionally, water that had built up from spring run-off had overwhelmed sediment and erosion control structures at the south end of the mine's quarry, pouring directly into the Flat River. The inspection report states "a noticeable sediment plume was observed" in the river.

The amount of sediment that entered the Flat River is unclear. Spill reports were filed after the inspectors discovered the leak, according to their report, but at press time the reports had not been posted to the GNWT Environment and Natural Resources spill database.

North American Tungsten, which is responsible for the care and maintenance of the mine site, was given orders from Morton to immediately implement erosion and sediment control measures throughout the quarry's south side drainage channel, which flows to the Flat River, and immediately implement sediment control measures on the river's shoreline.

A May 17 update from North American Tungsten's senior environmental co-ordinator, Kyle Conway, states the company has constructed a berm to permanently prevent sediment from entering the river. Additionally, sediment fencing has been installed along the shoreline between the berm and the river.

The update also notes the built-up water was moved at least 90 metres away from the river.

Leaks and lining tears

Among a multitude of issues identified during the inspection were leaks from the mine's portal diesel tank system, leaks from piping that runs between the mine's diesel bulk tank farm and transfer station, multiple tears in the tank farm's lining and leaking drums of hazardous waste.

Since the inspection, the storage area where the drums were leaking has been deemed out of service and the contents have been put in new drums, said Conway in his update to Indigenous and Northern Affairs Canada.

Additionally, a cache of 49 fuel drums near the mine site's airstrip were stored on lining that was beginning to lift.

North American Tungsten's report said when workers inspected the containment area they discovered the front side of the area's berm could be compromised and needed to be repaired. The back side of the berm also underwent repairs.

"NATCL believes that these actions address all the deficiencies identified and have returned the site back into compliance with the terms of the water licence and associated (land use plan)," Conway wrote in his report.

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