Seven years after Canada’s largest tailings spill, the two engineers who were involved have been found in breach of their professional codes of conduct.
On Aug. 4, 2014, a four-square-kilometre tailings pond breached at Mount Polley mine in central British Columbia, leaking vast amounts of water and effluent into Polley and Quesnel lakes and Hazeltine Creek.
More than 17 million cubic metres of water and eight million cubic metres of tailings effluent — containing toxic copper and gold mining waste — flowed into lakes and streams that served as a drinking water source and sockeye salmon spawning ground in the province’s Cariboo region. The 40-metre-high tailings dam was built on a sloped glacial lake. That weakened its foundation.
Mount Polley mine records filed with Environment Canada reported that hundreds of tonnes of arsenic and lead, as well as other heavy metals including copper and nickel, flowed out in the sludge.
Images of the sickly green effluent polluting the waterways showed the devastating impact of the spill into lakes that are also famed for large rainbow trout.
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