Tailings are finely ground waste rock produced as a by-product of standard mining projects as well as some industrial and power plant operations. Tailings are conventionally impounded behind a dam that is raised perpetually insofar as operations continue, thus amassing large volumes of materials (sometimes including supernatant pond water) in the process. The failures of some tailings impoundments have triggered downstream mass movements that have caused human, economic and environmental impacts, thus inviting considerable public attention and scrutiny. Developing a detailed inventory of these tailings flows facilitates a better understanding of the magnitude-frequency statistics, preconditioning and trigger variables, breach-outflow processes and downstream runout behaviour. Upon screening over 350 historical waste impoundment failure incidents in pre-existing secondary datasets, we have developed a comprehensive global database of 63 tailings flows from 1928-2020 while following strict case selection criteria with the support of satellite imagery, digital elevation models (DEMs) and source literature. Using a novel runout zonation method, the satellite images and DEMs were analyzed on geographic information systems (GIS) platforms to independently estimate runout distances, inundation areas and travel path angles of tailings flows. Depending on data availability or quality, we also summarized the background information, impoundment conditions and geotechnical indices to provide site-specific context to case histories. The collated data is aimed to (i) broaden the scholarly understanding of tailings breach-runout behaviour, (ii) provide comprehensive documentation while assessing the limitations of data availability and/or quality in the public domain and (iii) establish a consistent framework for reporting various properties of tailings dam failures and tailings flows. Lastly, we note that the data should be treated with prudence. Tailings impoundments are highly variable depending on the locality, and site-specific conditions exert strong controls on post-breach behaviour. As such, it is recommended that our database be used purely as a basis for screening-level assessments, case analog comparisons and academic research. For site-specific prediction studies undertaken by practitioners, targeted field observations, laboratory investigations and numerical models are essential.
Report and appendices to the report available on the bottom of this web page. Appendices are relatively technical.
CanBreach is a NSERC-funded university-industry research team whose purpose is to equip engineers with better tools, including computer simulations, to help manage the risks associated with tailings storage facilities. Using an integrated approach to research, the team will work to develop a better understanding of the mobility of tailings flow, breach mechanisms of tailings dams and the downstream behaviour of long runout tailings flow.
While not specific to tailings, this webinar includes valuable knowledge for tailings engineers. This webinar demonstrates the differences between Level Pool reservoir routing and Dynamic reservoir routing for dam breach modeling. Though the concept would apply to any 1-d hydrodynamic model, this webinar is designed around HEC-RAS. Given its stability and ease-of-use, Level Pool routing can be a more cost effective way to simulate the drawdown of a reservoir during a dam breach event, when compared to the more accurate, yet more computationally demanding Dynamic routing. The required input is simply a definition of the reservoir's stage-storage relationship. Dynamic routing requires much more detail, including cross sections that represent the bathymetric terrain in the reservoir, and is prone to instabilities, which can require a great deal of time and effort to work out. While Level Pool reservoir routing is a convenient method to simulate dam breach reservoir drawdown, it is not always appropriate and if misused, can lead to significant errors in computing the dam breach outflow hydrograph. This webinar explains when, and under what circumstances a Level Pool analysis is appropriate for dam breach modeling and demonstrates the input requirements and geometry setup for both Level Pool and Dynamic routing in HEC-RAS.
BC Chief Inspector of Mines - The Mount Polley tailings dam, owned by Imperial Metals, breached 4 August 2014, releasing its free pond water and a portion of the tailings into Polley Lake. The spill flooded Polley Lake, creating a plug at Hazeltine Creek, and continued into nearby Quesnel Lake and Cariboo River. The cause of the dam breach and subsequent tailings spill has been investigated with a final report published 31 January 2015, the Independent Expert Engineering Investigation and Review Panel assessment of the Mount Polley Tailings Storage Facility Breach.
At approximately 12:28 p.m. local time on January 25, 2019, tailings dam B-I at Vale S.A.'s Córrego do Feijão Iron Ore Mine ("Dam I"), located 9 kilometers (km) north-east of Brumadinho, in the state of Minas Gerais, Brazil, suffered a sudden failure, resulting in a catastrophic mudflow that traveled rapidly downstream. This report presents results and interpretation of the assessment of the technical cause(s) of the failure of the Dam I at the Córrego do Feijão Iron Ore Mine (the "Investigation")
Independent Expert Panel - The Mount Polley tailings dam, owned by Imperial Metals, breached 4 August 2014, releasing its free pond water and a portion of the tailings into Polley Lake. The spill flooded Polley Lake, creating a plug at Hazeltine Creek, and continued into nearby Quesnel Lake and Cariboo River. The cause of the dam breach and subsequent tailings spill has been investigated with a final report published 31 January 2015, the Independent Expert Engineering Investigation and Review Panel assessment of the Mount Polley Tailings Storage Facility Breach
The Cadia tailings dam, owned by Newcrest and in New South Wales Australia, failed on March 9, 2018. Extensive geological investigations, including drilling and sampling activities to characterise the site, laboratory tests, both routine and advanced, were performed to determine the range of properties exhibited by these materials, and Advanced numerical simulations of both deformation behaviour and ultimate failure states were computed to validate the hypotheses of the cause(s) of the Event under consideration.
Risk-Informed Decision-Making (RIDM) is a method of dam safety evaluation that uses the likelihood of loading, system response given the loading, and consequences of failure to estimate risk. This risk estimate can be used to inform decisions regarding dam safety investments. This approach has many benefits including a greatly improved understanding of the safety of the dam and identifying dam safety vulnerabilities that have not been identified using standards-based evaluation techniques. This website includes dam safety guidelines to evaluate consequences of failure and is intended for use on water dams.
Root Cause Analysis of the December 22, 2008 Failure of the Ash Disposal Cells at the Tennessee Valley Authority (TVA) Kingston Fossil Plant in Roane County, Tennessee. This report summarizes field exploration, laboratory testing, analysis and the evaluation of probable failure modes leading to failure.