The technology of mine tailings dams has always been largely separate from that for conventional water-retention dams. Although the two types of structures share many common analytical techniques, different traditions for both design and dam safety activities have developed within the mining industry as compared to hydroelectric and related areas of dam engineering. Some of these differences are firmly rooted in the different characteristics of the structures and the nature of the contents their impoundments retain. Nevertheless, recent trends in tailings dam safety have wider implications for the larger dam safety community and the issues that promise to confront it in the future.
The basic types of tailing dams including upstream, modified centerline, centerline and downstream construction methods are described and the pros and cons of each presented. Key issues that dictate the type of dam to be selected will be discussed. These issues typically include tailing properties, site characteristics, site seismicity, construction materials including tailing and beneficial use of other materials generated by the mining process will be discussed. Alternate types of deposition will be described ranging from single point to multiple spigots to subaerial deposition. Also tailing dams will be compared to water dams to show the differences in design approach. One of the key differences is the approach to the use of drainage.
Releases of mining tailings effluents and solids from containment facilities around the world have heightened awareness that risk associated with tailings impoundments must be fully addressed during all phases of a mine life. Bruce Geotechnical Consultants Inc. and Oboni Associates Inc. have developed a quantitative risk assessment process that allows mine owners and operators to quickly and successfully identify problem areas, and assess mitigative methodologies and priorities. The numerical method allows comparison between mines on a company wide basis and provides a platform for decision making as part of a risk management program. This paper focuses on how to conduct a quantitative risk assessment and provides a series of examples highlighting the principles involved and the advantages and disadvantages of using a quantitative risk assessment.