Wild Border Watersheds

British Columbia Planning Major Mining Operations, Despite Mount Polley Tailings Pond Blowout (Engineering News-Record)

Imperial Metals Corp., owner of the mine that caused Canada's worst mining disaster in history, has started limited production at an even bigger mine, which could be a threat to Alaska's $2-billion annual salmon and tourism business.

Meanwhile, Imperial has applied for a temporary restart of Mount Polley Mine, where a tailings storage pond failed in August 2014, spewing 4.3 billion gallons of water and 10.3 million cu yd of mine tailings and construction waste into two lakes and a creek that are part of the Fraser River watershed in British Columbia.

The Mount Polley spillage affected Quesnel Lake—a fjord-type lake in which salmon spawn—dumping chromium, cobalt, copper, iron, silver, vanadium and zinc. Hazeltine Creek, between Polley Lake and Quesnel Lake, got those same minerals as well as arsenic, manganese, mercury, nickel, thallium and titanium.

However, the other British Columbia mines—under construction, in startup or still undergoing assessment—pose a greater threat: acids that are common in copper and gold mining and other metals toxic to aquatic life.

The effects from Mount Polley "may take years to be felt by salmon," thanks to the metals bound to sediment settling in the lake bottom, says Aaron Hill, executive director of Watershed Watch Salmon Society. The greater danger, he says, is with the other mines.

"Even though Mount Polley was one of the biggest environmental disasters in Canadian history, the impact would be much worse from a catastrophic failure at a project like Red Chris and KSM [Kerr-Sulphurets-Mitchell] that are acid- draining, with much larger tailings impoundments," he says.

"KSM, which was quietly approved by the federal government over the Christmas holiday, would have two tailings impoundments around the same size as Hoover Dam," he adds.

(To read complete source article, click "Engineering News-Record")

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