Maligned mine remediation project east of Yellowknife ahead of schedule, say federal officials

A year after inspectors said they were "extremely disappointed" with the federal cleanup job of a cluster of seven abandoned mine sites, its project manager says the remediation has become a model of success.

The cluster of mines, about 70 to 90 kilometres east of Yellowknife, were built at a time when mining regulations were nearly non-existent, then intermittently used before being abandoned.

Site investigations began at the old mines in 2009, where federal officials found open mine shafts, abandoned oil drums, old equipment, and open tailings ponds. They hired a private contractor in 2016 to remediate the sites.

Tailings, contaminated soils and metal debris from the seven sites were put into two landfills. Some soil contaminated with hydrocarbon was treated by aerating it, and other soil was shipped off site. Hazardous materials like lead paint and oil were also sent south, and some old mining equipment was given to regional historians.

Changes made after inspection

The 2017 inspection found that the clean-up team had failed to report a hydrocarbon spill, failed to stop petroleum products from spreading to surrounding lands, failed to use drip trays under leaking equipment, failed to clean up all leaks and contaminated material, failed to report a truck fire, and — among other things — operated a quarry too close to a body of water.

A federal official speaking on background said the quarry was only pre-operational due to a miscommunication and that a petroleum spill happened when the contractors were not away from the site due to spring thaw.

Project manager Ron Breadmore said inspectors last year caught his team at their worst.

"Since the inspection was conducted, the project team reviewed its project controls and put additional measures in place," said Breadmore, who works with contaminated site remediation for the federal department of Indigenous and Northern Affairs.

For example, he said, the team added hay bales toward the end of a marsh that pours into Bullmoose Lake, to slow down the erosion of sediment rich in metals like iron that could affect the mineral balance of the lake.

Consulted community while project happened

Breadmore told CBC he was also proud of the way the federal officials responded to community input.

For example, contractors had begun putting in posts for a precautionary chainlink fence to keep large animals from eating plants that "has some metal impacts in it," he said in a technical briefing.

That plan was kiboshed, because the risk of wildlife getting caught in the fence was perceived to be higher than any risk from eating the plants.

What's next?

The contract for the mine cleanup cost $15.6 million, said Breadmore. Now officials will be adding vegetation to some of the newly-cleaned plots and monitoring the situation, at a cost of an additional $6.9 million.

For example, mine water continues to flow up from underground near Bullmoose Lake. The team built a structure to make it easier to measure metal content in the water before it mixes with the nearby marsh.

"You can't stop it. It's just something we've accepted. But at least we can measure and monitor it — and if any time the wetland because saturated and can't uptake those metals anymore — we would come in," said Breadmore.

The team will also be monitoring landfills, one of which was built in the winter — an unusual approach, he said.

"Typically we don't build landfills in the wintertime," said Breadmore. "If you have a lot of ice in your soil that could be a problem." The contractors used drier soil to solve the problem, and the cap on top of the landfill "survived the first winter no problem."

Breadmore said the project team wants to make sure that any residual metals aren't hurting lakes or plant life, and will be monitoring to make sure that the structures they made to cover up old mine holes stay intact.