WORLD DISTRIBUTION OF TAILINGS BY HAZARD POTENTIAL
Within the total world portfolio of 29,000-35,000 TSF’s (excluding closed facilities but including abandoned) there are few available data points on hazard potential. As employed in most instances, hazard potential, as distinct from actual risk, describes the relative severity of loss in the area that would be affected in the event of catastrophic failure (in the WMTF typology, a “very serious” failure). Based on data on 2,800 facilities in two national portfolios (USA and Brazil (n=1,800 total) and the COE disclosures (N~1043) we nevertheless estimate with reasonable confidence that 50% to 60% of all presently existing tailings depositions, 267bn m3 to 326bn m3 , are in high hazard potential TSF’s. We further estimate with reasonable confidence that 60% to 65% of the 136bn m3 of all tailings, from world mineral production in the next 5 years will be to existing high hazard potential facilities. Very little of that will be deposited into new TSFS.
It is not possible to estimate what percentage of all existing TSF’s, including those scheduled to receive depositions 2019-2024 have a current hazard potential classification.
It is also not possible to estimate what proportion of all panned depositions 2019-2024 will be to high hazard potential facilities as only the COE disclosures included the variable we recommended, “Planned Depositions Next 5 years”. We don’t believe the COE disclosures are representative of the world portfolio because of measured differences on size, hazard potential, operational status, and dam characteristics. Those disclosures show a net increase in depositions of x and an increase to High Hazard Potential facilities of y%))
HAZARD POTENTIAL VS ACTUAL RISK
The following examples illustrate that a high hazard potential does not necessarily indicate a high actual risk. Actual risk cannot be presumed from hazard potential alone. A high hazard potential does though indicate the level of care needed to prevent failure.
Europe’s largest tailings facility, “Zelazny Most”, Poland, is a “very high” hazard potential facility where measures have been taken to address the inherent long delineated vulnerabilities of upstream construction and also to recognize , assess and monitor flow failure risks and other aspects of dam stability.
