Provincial failure to properly regulate the design and operations of dams means more failures coming
The failure rate for mine tailings dams like the one at Mount Polley has been consistent worldwide at about one every eight months since 2001.
Lest anyone think that “worldwide” refers mostly to a problem in the developing world where impoverished governments can be co-opted to accept lower safety standards because they are desperate for tax revenue, a United Nations study found that 39 per cent of these failures were in North America.
The reasons for tailings dam failures vary from shoddy construction and use of inappropriate materials to seismic or other unavoidable environmental events. However, according to a 2010 survey of all the known tailings dam failures in the past century, most fail for two reasons.
The first is unusually heavy rains that overwhelm dams’ designed capacities. They account for 40 per cent of failures. The second is poor management and flawed regulatory oversight, responsible for 30 per cent of failures.
Why should this be of particular interest to British Columbians after the Mount Polley collapse, which spilled 24 million cubic metres of effluent and contaminated sediments into the pristine Quesnel River watershed?
Because if you compare dam failures from before 2000 with failures since, the number of dams failing due to extreme rainfall events has increased by 60 per cent. The number failing due to poor management and regulatory oversight has increased by 200 per cent.
This has implications for industry specialists, policy makers and regulators in B.C. after Mount Polley. Reducing risk will require a lot more political will than we’ve so far seen from a government that often behaves like a captured agent of the resource sector.
Considering what’s coming, we will need more rigorous standards and more aggressive insistence upon compliance.
Why can’t it be business as usual? Government itself acknowledges that it expects a dramatic increase in the frequency and intensity of both seasonal and unusual precipitation. “The extreme weather events of greatest concern in B.C. include heavy rain and snowfall,” it says.
Government planners cite, for example, extreme rainfall in 2010 which forced evacuation of communities and warned that such heavy precipitation will occur over many regions of the province.
Independent and government scientists, researchers, meteorological forecasters and emergency responders met in 2013 to review and summarize current knowledge about the implications of what’s coming. They reached the following conclusions.
“Larger increases in precipitation are projected for B.C. than for the global average, in particular for the coastal regions. The frequency of extreme events is also expected to increase.” Events that occurred on average once in 20 years will begin happening once a decade.
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