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Dam collapse: Government was involved in inspecting structure, so a true arms’-length investigation essential
The engineering firm that designed the Mount Polley tailings pond containment system that collapsed on Aug. 4 also designed a tailings dam that failed catastrophically in South America on Aug. 19, 1995.
Knight Piésold designed the tailings containment facility for the Canadian-owned Omai gold mine in Guyana. Before the accident, it had handed off operational responsibility to the mining company, which then hired another engineering consultant, the Canadian firm Golder Associates.
The Omai tailings dam collapse spilled an estimated 2.9 million cubic metres of toxic waste into the Essequibo River, the country’s biggest and most important watershed. (Some estimates run higher.) Guyana’s President Cheddi Jagan, whose government held a five per cent share of the mining venture — it was the poor country’s largest private sector employer — and had been championing its economic benefits, called it “the country’s worst environmental disaster.”
A subsequent inquiry found no criminal liability and a civil class action suit was later dismissed. It’s worth noting, perhaps, that by comparison the Mount Polley tailings dam failure, which B.C.’s Mines Minister Bill Bennett has equated with a simple natural landslide, spilled 14.5 million cubic metres — about five times as much contaminated waste as at Omai — into the Fraser River system, B.C’s biggest and most economically important watershed.
The most hazardous component in the Guyana accident was cyanide. The accident at Mount Polley released sediments contaminated mostly with arsenic and heavy metals.
Environment Canada lists on-site tailings disposal totals for the Mount Polley mine as including 969,993 kilograms of arsenic, 625,322 kilograms of lead, 19,940 kilograms of cadmium and 5,197 kilograms of mercury.
Environment Canada says of these listed compounds:
• “Arsenic has been consistently demonstrated in numerous studies to cause cancer in humans” and “there is believed to be some chance of adverse health effects at any level of exposure.”
• “Cadmium compounds have been classified as ‘probably carcinogenic to humans’ … there is believed to be some chance of adverse health effects at any level of exposure.”
• “Lead is a highly toxic metallic element … even small amounts of lead can be hazardous to human health.
• “Mercury is toxic and has the ability to pass the blood-brain barrier and affect the central nervous system.” The most common form of mercury uptake is eating contaminated fish. It’s of particular concern for pregnant and lactating women and small children whose developing nervous systems are vulnerable.
For the rest of this column, click here: http://www.vancouversun.com/news/Stephen+Hume+Mount+Polley+inquiry+must+independent/10126049/story.html