WSJ: Mining Dams Grow to Colossal Heights, and So Do the Risks

[mbig]

These things are obviously disasters waiting to happen.
Probably worse in developing or Third world countries, but We have them too.
Very good graphics, Can only post a few.
Hope you can see more as WSJ is subscription for most articles.

Mining Dams Grow to Colossal Heights, and So Do the Risks - WSJ
Engineers say Brazilian disaster shows world-wide danger from Hoover Dam-size earthen structures holding ‘tailings’ waste
By Paul Kiernan - Wall Street Journal
+ Extensive VIDEOS and Graphics

Mariana, Brazil—Half an hour’s drive from this colonial town in southeast Brazil, trees suddenly give way to what looks like a desert salt flat. It is a 2-mile-wide valley filled with mine waste.

On Nov. 5, an earthen dam holding back this sea of sludge collapsed, releasing a deluge that killed 19 people, destroyed villages and traveled more than 400 miles to the Atlantic Ocean, where it left a reddish-brown plume visible from space. As tall as a 30-story building and holding enough refuse to fill 19 Dallas Cowboys stadiums, the dam was the largest structure of its kind ever to give way.

It won’t be the last. From Chile to Australia to the U.S., the quest for economies of scale has prompted mining companies to dig larger and deeper pits, creating record volumes of waste. To house all that detritus they have constructed some of the most colossal man-made structures on the planet. Known as tailings dams, these earthen embankments hold back sprawling reservoirs of mud, finely ground rock and water—what is left after a mill separates metals from ore.

In theory, tailings dams are intended to last forever. In practice, they fail often enough that industry engineers themselves are sounding alarms. Fifteen months before the Brazilian disaster, Canada suffered its biggest tailings-dam failure at a copper mine that was in full compliance with local regulations. Experts estimate that between one and four breaches occur each year at tailings dams world-wide, roughly 10 times the failure rate of water dams.

The largest tailings dams, at copper mines high in the Peruvian Andes, are already as tall as the Hoover Dam and have permits to rise even further.

“Our dams and dumps are among the highest-risk structures on Earth,” ...
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One Video
Mining Dam Failures Present a Global Danger
4/4/2016 10:31AM
Massive tailings dams, like this functional one near Antonio Pereira, Brazil, are built by mining companies to hold back the sludge left behind when a mill separates metals from ore. But the dams fail often enough that industry engineers are sounding alarms. Photo: João Pina for The Wall Street Journal