Tailings dam failures – can we minimise the risks? – by Craig Goff (Water Power Magazine – May 21, 2019)


Following the recent catastrophic failure of the Córrego do Feijão tailings dam in Brazil, Craig Goff from HR Wallingford considers the risks associated with these types of dam

The terrible human tragedy at a mining dam in Brazil in February 2019 has once again raised awareness of the risks posed by dams located upstream of population centres.

Dam failures of any type are fortunately rare, but, when they do occur these are incidents that can have severe consequences with mass loss of life and environmental and financial consequences in the billions of dollars. It is therefore crucial that we minimise the chance of a dam failure by rigorously improving safety at each point of the dam lifecycle.

What causes dams to fail?

There are typically two main ways an earthen embankment dam can fail – either by internal erosion or external erosion. In the case of internal erosion, water penetrates the outer waterproof barrier and erodes material away from within the body of the dam, creating a hole that gets bigger and bigger until the embankment can no longer hold back the force of the water in the reservoir.

With external erosion, water from large waves or uncontrolled rising water levels flows over the top of the dam and erodes material away from the outside, leading to the same effect.

The earliest large dams date back to about 3000BC. It is telling that the earliest known example (Saad-el Kafara, Egypt) is thought to have failed during construction, with the devastation caused dissuading ancient civilizations from similar large dam construction for a period of some 800 years.

For the rest of this column: https://www.waterpowermagazine.com/features/featuretailings-dam-failures-can-we-minimise-the-risks-7217097/