Mine Tailings Storage: Safety Is No Accident

Using natural materials water supply reservoir dams have only one design option – known as downstream type construction. Tailings dams sometimes use this construction type, but more often use, what is termed Water and Tailings dam construction methods

centerline or upstream- construction, designs that water supply reservoir dams cannot employ. Centerline and upstream dams are not as inherently safe as downstream construction.

Types of sequentially raised tailings dams

Upstream

4

3

2

1

Starter dyke: 1.

The dam design terms, upstream, downstream and centreline, indicate the direction in which the embankment crest moves in relation to the starter dyke at the base of the embankment wall. Dyke: 2 to 4 or more Dykes are added to raise the dam wall. This continues throughout the operation of the mine.

Downstream

4

3

2

1

Centreline

1 2 3 4

L ÓPEZ , 2017

Source : Vicks 1983, 1990

Figure 9. Dam building methods

Causes of failure

In the literature on the topic, the majority of the tailings storage-facility failures discussed can be attributed to a few factors – in particular, the lack of management continuity and inadequate resourcing (especially financial) for the facility (Figure 10). In cases of failure triggered by mechanisms such as overtopping or piping, inadequate management has occurred over a period of time. The failure may ultimately have been triggered by a particular mechanism, but the tailings storage facility should never have been permitted to reach a point where it was susceptible to such a triggering mechanism in the first place. In the case of failures due to earthquakes, where the loading is rapid and unexpected, the initial design of the tailings storage facility is the most important management consideration. The design needs to be fit for purpose – for example, tailings storage-facility studies indicate that the upstream method of dam construction is more susceptible to

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