Dam Breach Analysis in Tailings Storage Facilities (TSF): Fid-Bau Portal

Dam Breach Analysis in Tailings Storage Facilities (TSF)

Bernedo, Carmen E. / Julien, Pierre / Leon, Arturo

Dam breach analysis and flood-wave routing is needed to assess the effect of a potential dam failure downstream of a Tailings Storage Facility (TSF), which in turn will guide on selecting the appropriate Emergency Action Plan (EAP) for the TSF under a potential dam breach. It is known that in the industry specific guidelines and/or procedures to perform dam breach analysis for TSFs and the resulting "flooding conditions" are not available as they do for water dams. The purpose of this paper is to assess potential downstream impacts that may result from various failure mechanisms in a dam breach of a TSF to be used as a case study. For the analysis, we use the characteristics of a TSF located in a setting where short duration high intensity precipitation events result in rapid and large changes inflow conditions. The simulation involves the liquefaction of an impoundment with a capacity of approximately 12 million tons of non-Newtonian tailings materials released from a 80 m high dam. The modeling analysis of a TSF dam breach is evaluated under likely modes of embankment dam failure from published information as well as likely modes of failure applicable to the TSF dam. The flow routing was developed assuming two different conditions: (1) assuming that the tailings behave as water during the routing process, and (2) assuming that the tailings behave as a dense non-Newtonian homogeneous flow (e.g., liquefied tailing). The results of this detailed non-Newtonian TSF breach modeling analysis shows that velocities up to 20 m/s can be reached in very steep mountain channels. This mean flow velocity is approximately five times the shear velocity and the results are comparable to numerous field observations ofmudflows and debris flows in steep mountain channels.