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Tailings storage facility (TSF) design has long been based on deterministic limits. By extension, the TSF owner accepts a Probability of Failure (PF) associated with these deterministic limits which are assessed against industry norms with respect to investigation/analysis and design assumptions related to the operation of the facility. If the Probability of Failure of a design that is derived in this way is taken as the likelihood related to the tolerable risk limit, it follows that the same, or a lower PF, should be maintained during operations. Examples of operational controls include pond management and inspections/monitoring. Upset conditions arise when operational controls are not being implemented. Therefore, by comparing the calculated PF of the TSF complying with the design assumptions and the PF for the same TSF in an upset condition, the required PF of operational controls can be estimated. This concept assists the TSF owner in determining what is required to safely operate the facility and communicate the geotechnical risk to all stakeholders. By extension, scenarios where a TSF owner cannot achieve the required PF of operational controls can be addressed with: 1. Greater rigor applied to operational controls. 2. Addition of more operational controls. 3. A change to the design assumptions, where the timing of the project allows. This method provides a measured approach to risk management in the design and operational phases, without a TSF owner having to quantify an acceptable risk tolerance. Instead, the design is based upon widely accepted practice and industry/business accepted safety, economic and environmental risk levels. Subsequently, the design PF can be calculated and then applied as a benchmark for operations. This approach serves to reduce uncertainty through alignment of the design and operation phases. The concept is explored for three different tailings storage methods: upstream raised TSF, downstream raised TSF, and impoundment by mine waste dumps, to estimate how sensitive each storage method is to the type and effectiveness of operational controls implemented by the dam owner.
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Many publications are available that provide statements of best practice in terms of open pit slope risk management. However, to date none provide a risk model that demonstrates the risk reduction achieved for applying each of the risk management elements. This leaves the slope stability practitioner unable to analytically answer questions such as: ? How frequently should slopes be inspected? ? How frequently should prisms be read? ? Should a radar be acquired? If so, which one? ? How many monitoring systems to use? And many more. This paper applies the Venter and Hamman (2018a) temporal safety risk model to an open pit in West Africa. The paper demonstrates the use of the model to a small saprolite open pit and concludes with recommendations for slope instability registers to facilitate future back?analysis in terms of this model.
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Planning, operating, monitoring and closing a tailings storage facility (TSF) can present many challenges, especially in dynamic mining environments where site conditions vary spatially and with time. However, big impacts can be made at relatively small cost once the tailings management system, design and performance are well defined and understood. This paper presents various examples of initiatives aimed at achieving the design intent that have been adopted by Rio Tinto Iron Ore, which also reduce risks and improve tailings management performance. Examples presented include development and communication of short-term, long-term and life-of-facility deposition plans, implementation of simple deposition management tools, monitoring and managing slurry density, development and continual oversight of water balance models, and sound investment in water management infrastructure extending to safe performance in emergency situations. Regular governance was also implemented to provide assurance that these controls remain effective.
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An awareness of the rate at which water resource development took place in South Africa being supply driven, until relatively recent times, leads to an appreciation of the changing philosophy in respect of water conservation and pollution control, as well as essential amendment to principles and procedures. Reconciling water demand and supply in catchments requires concurrent consideration of available water quantity and quality. This stimulates the need for change in the way we view water uses and brings about business opportunities in the sector. The review of infrastructure designs in support of water use and mining applications for industrial and mining waste has developed and transformed along with improved technology and changes in legislation since 1994 in South Africa. A containment barrier system comprises of both filter protected drains and low permeability liners which are visible in the short term until covered. They are required to perform effectively after initial use and are often inaccessible for the operating period and subsequent service life of decades or even centuries. This paper presents a regulators perspective of commonly repeated deviation from accepted norms and standards in the engineering profession, as applied to pollution control facilities. Emphasis is placed on the standards of today with experience reflecting on the past five years of design reviews, leading to conclusions and recommendations for facility owners and practitioners. Examples of procedure, mechanisms, performance, specifications and socio-economic benefits are addressed. It is postulated that in the near future many mining and industrial developers will choose to improve containment standards of barrier systems as a component of reengineering water demands and for economic advantage while embracing contributions from ecosystem services.
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There are growing expectations of mining companies to operate in a more sustainable manner, with a strong business case for improving waste management and reducing environmental impacts. As the stewardship of tailings come under increasing scrutiny, decision-makers are urged to adopt a robust approach to the selection of a tailings management strategy that encompasses design for closure, and leading practices to lower the risk of catastrophic dam failures, optimise the use of resources, and mitigate environmental impacts on climate change. An integrated analysis, considering economic, environmental, social, and risk aspects of the operation can therefore provide decision-makers with balanced information to ensure the right projects proceed with an optimal business case so that the most cost-effective solution, that does not externalise costs, can be selected. However, literature review revealed that fundamental shortcomings exist within traditional evaluation approaches used for economic comparisons. This paper reports on life cycle cost analyses conducted for comparing various tailings management options under different scenarios. A conceptual case study for the disposal of gold tailings in Western Australia as a slurry, as thickened, or as filtered tailings, was considered. This was done for examining the extent to which potentially hidden costs impact on the total cost of a project. It is suggested that the proposed approach will lead to selection of a tailings management alternative that ensures sound economic, environmental, and social performance is achieved.
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Report and appendices to the report available on the bottom of this web page. Appendices are relatively technical.
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ASDSO is a national non-profit organization serving state dam safety programs and the broader dam safety community to improve the condition and safety of dams through education and support for state dam safety programs. Largely focused on dams for flood protection, water supply, hydropower, irrigation.
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This bulletin is intended primarily for the use of the Regulatory Agencies responsible for the safety of tailings dams, both structurally and environmentally. However, it is also intended to assist the mine operator in understanding the measures that must be adopted to ensure that his tailings dam is safe, both during operation and after rehabilitation. Finally, it should also benefit those individuals or organizations involved in the design, construction, operation, and rehabilitation of tailings dams.
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Innovation flourishes at the intersection of great challenges meeting compelling solutions. Canada's Oil Sands Innovation Alliance (COSIA) is an alliance of oil sands producers focused on accelerating the pace of improvement in environmental performance in Canada's oil sands through collaborative action and innovation. COSIA's membership accounts for over 90% of the oil sands product in Canada. Canada's oil sands producers are competitors and rivals; but they are also partners in a made-in-Canada collaboration model that is helping to redefine, globally, how companies can innovate together, and accelerate solution development to address some of the world's biggest challenges. COSIA companies are working aggressively to accelerate the pace of environmental performance improvement in the oil sands. Canada's oil sands industry is committed to reducing all aspects of its environmental footprint, reclaiming all lands affected by operations, and maintaining biodiversity. To create breakthrough science and technologies, COSIA brings together leading thinkers from industry, government, academia and the public. In addition, COSIA members themselves work together, each sharing considerable in-house expertise, innovation and intellectual property within the alliance, and dedicating substantial funds to COSIA's many environmental performance projects. The unique characteristics of oil sands tailings provide member companies with an opportunity to seek out innovative tailings management and technology solutions for responsible and sustainable growth of this key global energy resource. This keynote address will elaborate on each of the Environmental Priority Areas (EPA), with an emphasis on the Tailings EPA. It will provide the audience with a brief history, achievements, current technical challenges, and opportunities for collaboration to close remaining knowledge and technical gaps to accelerate the pace of environmental performance improvement.
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Geohazards comprise a subgroup of natural hazards associated with geotechnical, hydrotechnical, tectonic, snow and ice, and geochemical processes that can pose a threat to worker and public safety, asset integrity, and asset management lifecycle cost. Like for most types of threats, the risks from geohazards can be assessed qualitatively or quantitatively and used to inform a geohazard management program. Most mining companies use risk matrices to aid in the assessment, prioritisation, communication and management of corporate risks. These matrices use standardised descriptions of likelihood and consequence to help users assess risks of negative outcomes to health, safety, the environment, assets, and reputation, and are tailored to each organisations types of risk exposure and level of risk tolerance. Geohazards and related geotechnical failures can represent low-probability, high-consequence events that plot in the highest risk zones of most corporate risk matrices. Variability in spatial and temporal probabilities for people and infrastructure exposed to geohazards can have a large influence on risk exposure, and this can be challenging to assess and communicate effectively with some risk matrices. Risk is scale-dependent: the business risk due to rockfall from a single slope along a mine access road is vastly different than the total risk due to rockfalls from all slopes along that road, yet guidance is often missing on how the risks from these scenarios should be plotted on a risk matrix. These and other pitfalls associated with use of corporate risk matrices for informed geohazard management are explored.
