http://www.cbc.ca/news/canada/british-columbia
Porous soil at site of proposed tailings pond dam called a ‘major design issue’
The Canadian Press – The results of a third-party review into the design of a northwestern B.C. gold and copper mine says it has the potential to cause significantly more environmental damage than the recent collapse of the Mount Polley tailings pond.
Engineering firm Klohn Crippen Berger made 22 recommendations for the owner of the mine, Imperial Metals, to improve the tailings dam of the Red Chris mine, 500 kilometres north of Terrace.
The review found the design of the dam is feasible, but that there are issues that must be addressed. The three-phased review looks at the tailings pond design, water quality predictions and geohazards at the mine site.
It identifies a “major design issue” for the soil on which the dams would be built, noting the porous soil could cause damaging water leaks if the planned installation of a fine-grained tailings blanket isn’t enough to limit seepage.
It also suggests that designers carefully monitor the water balance for their tailings reservoir and complete a risk assessment around the effects of another nearby landslide.
Some of the report’s other suggestions include more detailed documentation, emergency response measures, environmental testing and design changes.
“Any technical lessons to be learned from Mount Polley cannot be applied to this facility because the forensic investigation into the cause of that failure has not yet been completed,” the report said.
“At the same time, any failure of the Red Chris impoundment will likely have a much more significant environmental impact than the Mount Polley failure.”
Tahltan elders’ concerns prompted review
The Tahltan Central Council instigated the review and Imperial Metals funded it after the company’s Mount Polley mine in B.C.’s central Interior failed in August, sending millions of cubic metres of wastewater and silt into a network of salmon-bearing lakes and rivers.
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