The term mining dams refers to retaining structures that exist at mine sites or metallurgical plant sites. There are two main types of mining dams: dams used to create tailings ponds or impoundments, and dams used to create ponds to hold water. For hard rock mines, tailings are a by-product of conventional mining; they are formed from the rock that is mined and then crushed to a fine sand and silt for processing and may contain solids (that may or may not be contaminated) and/or contaminated liquids. Considering also oil sand mines, tailings can be defined as "a by-product of mining, consisting of the processed rock or soil left over from the separation of the commodities of value from the rock or soil within which they occur" (Mining Association of Canada).
The Mining Dams Committee is responsible for identifying issues related to mining dams and then working with stakeholders and other CDA committees to develop solutions. In 2014, the committee completed a Technical Bulletin on how the Dam Safety Guidelines can and should be applied to mining dams. The Mining Dams Committee maintains strong relationships with other organizations including the Mining Association of Canada.
Dam breach analysis is an important aspect in establishing design criteria, in evaluating the risks to the downstream environment, communities, and infrastructures, as well as in the preparation of emergency planning documents. While such analysis is routinely conducted for water retaining dams, its application to dams that contain viscous solids, such as tailings, has been a challenge largely because of the uncertainties regarding the interactions between the tailings which may or may not be liquefiable and any free water that may be present. A working group of the CDA’s Mining Dam Committee had been working on developing a technical guidance document on this complex topic since 2014 and recently published a technical bulletin on Tailings Dam Breach Analysis (TDBA) – available at the CDA Store.
In the following presentation, hosted by the University of Alberta, Mamun Al-Mamun gives an overview of the bulletin including its scope, key features, its application, and limitations.