Chapter 2
Two Recent Catastrophic Tailings Dams
Accidents
This chapter sets the recent scene. Two catastrophic tailings dams failures (Mount
Polley and Samarco) are reviewed based on Independent Review Panel and other
post-mortem analyses.
2.1 Mount Polley
On 4 August 2014, a breach occurred within the Perimeter Embankment of the tailings
storage facility (TSF) at the Mount Polley copper and gold mine in south-central
British Columbia. The breach (Fig. 2.1) resulted in the release of an estimated 25
million cubic metres of wastewater and tailings that resulted in surface environmental
damage and the transport of tailings and water into a nearby lake. No lives were lost
but remediation costs are estimated by the company to be in the order of 70M$US (the
estimate reached 205M$US in 2018), and the company’s market value was adversely
affected.
The impact of the dam failure was judged by most external observers to be catastrophic. If measured against the current consequence characterization criteria established by the government of British Columbia, the consequence classification would
be at the significant level, three levels below the extreme impact classification. From
a corporate perspective, the impacts of the dam failure would have to be judged as
being of the highest order based on considerations related to the loss of market value,
operating earnings and public trust as well as the costs of remediation. In corporate
terms, such impacts would be judged as being material, requiring the highest level
of risk management and corporate governance.
In order to identify the cause of the failure and to assist in the identification of
improvements for tailings management in general, the initial response by the government of British Columbia was to appoint an Independent Expert Engineering
© Springer Nature Switzerland AG 2020
F. Oboni and C. Oboni, Tailings Dam Management for the Twenty-First Century,
https://doi.org/10.1007/978-3-030-19447-5_2
13
Two Recent Catastrophic Tailings Dams
Accidents
This chapter sets the recent scene. Two catastrophic tailings dams failures (Mount
Polley and Samarco) are reviewed based on Independent Review Panel and other
post-mortem analyses.
2.1 Mount Polley
On 4 August 2014, a breach occurred within the Perimeter Embankment of the tailings
storage facility (TSF) at the Mount Polley copper and gold mine in south-central
British Columbia. The breach (Fig. 2.1) resulted in the release of an estimated 25
million cubic metres of wastewater and tailings that resulted in surface environmental
damage and the transport of tailings and water into a nearby lake. No lives were lost
but remediation costs are estimated by the company to be in the order of 70M$US (the
estimate reached 205M$US in 2018), and the company’s market value was adversely
affected.
The impact of the dam failure was judged by most external observers to be catastrophic. If measured against the current consequence characterization criteria established by the government of British Columbia, the consequence classification would
be at the significant level, three levels below the extreme impact classification. From
a corporate perspective, the impacts of the dam failure would have to be judged as
being of the highest order based on considerations related to the loss of market value,
operating earnings and public trust as well as the costs of remediation. In corporate
terms, such impacts would be judged as being material, requiring the highest level
of risk management and corporate governance.
In order to identify the cause of the failure and to assist in the identification of
improvements for tailings management in general, the initial response by the government of British Columbia was to appoint an Independent Expert Engineering
© Springer Nature Switzerland AG 2020
F. Oboni and C. Oboni, Tailings Dam Management for the Twenty-First Century,
https://doi.org/10.1007/978-3-030-19447-5_2
13