Tailings dam failures have and continue to cause large-scale devastation and environmental impacts. Historically these impacts have largely been predicted using Newtonian hydrodynamic modelling principles resulting in a general overestimation of potential consequences. However, since about 2014 the collective mining industry began developing complex tools to better predict the likely impacts of these failures. The industry has focused on leveraging the latest in computational flow dynamics modelling software and computational hardware to preform non-Newtonian tailings dam break assessments. However, as our tools become more sophisticated so does the requirement on input data. This paper discusses the past modelling approaches and the development of non-Newtonian tailings dam break models. The sensitivity of the flow behaviour is presented through four case studies, showing how this selection influences the outcomes and how previous approaches assuming Newtonian characteristics may present an overly conservative result. It is noted that additional knowledge and expertise will become available as non-Newtonian tailings dam break studies become the norm. In the interim, the uncertainty of these analysis needs to be analysed.
South32 Worsley Alumina Pty Ltd operates several bauxite residue storage facilities at their refinery in Western Australia. The bauxite residue slurry is thickened and pumped onto the storage facilities which are constructed on an upstream basis using compacted earthfill embankments. BRDA 5 is the newest of the residue storage facilities, established in 1999, and has a current maximum height of embankment slope of 42 m, of which a compacted earthfill starter embankment makes up the first 22 m. Since 2010, the residue has been treated after deposition using amphirols, which assist in dewatering and compacting the residue. As part of their residue management commitments, Worsley undertook a dam break analysis entailing a review of all available geotechnical testing data, a fault-event analysis to evaluate the probability of removal of support to the residue through slope instability, overtopping, geotechnical piping or failure of a buried structure leading to liquefaction of the residue and a dam break. To model the flow of the liquefied residue, pilot-scale dam break testing was carried out from which estimates of the rheology of the residue were made. The rheology has been incorporated into a flow slide model that applies stream power entropy theory to define the energy changes due to viscous effects and frictional resistance. Benchmarking of the results against modelling using computational fluid dynamics has been made. This paper presents an overview of the dam break assessment process and results that covers a liquefaction potential assessment, a semi-quantified risk assessment based on a fault-event analysis approach, rheological testing of liquefied consolidated residue in a specially developed box rheometer and probabilistic modelling of the dam break, the outflow hydrograph, and the flow inundation areas. It is concluded that incorporation of rheology representative of liquefied consolidated residue in dam break modelling results in significantly reduced prediction of inundation area.
Decision Support System for Water Infrastructure Security Human Consequence Module (DSS-WISETM HCOM) is an analytical module for automated assessment of the human consequences of dam-break floods. The National Center for Computational Hydroscience and Engineering (NCCHE) and the University of Mississippi developed the module with funding provided by the U.S. Federal Emergency Management Agency (FEMA) through a contract with Argonne National Laboratory.
DSS-WISE Lite is a web-based, automated two-dimensional dam-break flood modeling and mapping capability developed by the National Center for Computational Hydroscience and Engineering (NCCHE), the University of Mississippi. The development of the web-based tool and its operation and maintenance is supported by the U.S. Federal Emergency Management Agency (FEMA).
Secure, web-based graphical user interface and map server providing analytical capabilities and a decision support system for dam/levee security.
This DVD has a suite of ArcGIS tools designed to support the development of simplifed dam break studies, Risk Mapping, Assessment and Planning (Risk MAP) datasets, loss of life assessments, Emergency Action Plans (EAPs), and EAP map panel creation. This version of GeoDam-BREACH can be used for various workfows including: Simplifed Dam Break Studies, Risk MAP Datasets, Loss of Life Assessment, EAP Map Panel Creation, and EAP Development. The Users Guide is a part of the CD. Dam Safety offcials across America is the targeted audience.