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.
Inherent uncertainty associated with the selection of input parameters to various geotechnical analyses often results in the likelihood of failure being a dominant topic in the discussion of risk associated with geotechnical assets. As a result, embankment failure is the default risk scenario driving ongoing management of tailings storage facilities (TSFs). This commonly applied approach is inefficient as it drives resource intensive TSF management and limits scope for a risk-based approach. However, many TSFs operate with several layers of controls in place. Therefore, assessment of risk with consideration of these controls would promote greater efficiency in TSF management. A fit for purpose approach will be discussed that demonstrates how risk can be utilised as the foundation for the development of a management framework for a single or portfolio of TSFs. This approach focuses on the identification and monitoring of controls, based on the understanding that hazards impact when the controls put in place to manage them fail. It is necessary to build such an approach with the full application of risk principles, which will be introduced by a specialist in corporate risk. Topics covered include a brief history of risk, importance of control effectiveness in scenario selection and risk evaluation and communicating value at risk to drive resource allocation. It is hoped that this discussion and presentation of simple examples allows risk concepts to be better applied to the design and management of geotechnical structures.
Operational control and trigger action response plans for tailings storage facilities (TSFs) routinely measure a number of operational aspects to assess risk and ensure the TSF does not exceed certain design considerations. Measurements that are routinely used for this purpose include topographical surveys and beacon settlements, density and moisture measurements, and discharge characteristics, among others. A statistical analysis of the cumulative historical operational datasets from a TSF allows improved knowledge of the level of variability of the considered parameters, and potentially enhances risk-based decisionmaking by increasing the understanding of uncertainties and the potential for expected deviations during operations (ICMM 2021). The inclusion of a probabilistic dataset in the design inputs allows a performance-based approach to managing a TSF, considering a series of scenarios defined by performance objectives, determining key factors to identify them in a timely manner, and incorporating effective corrective or failure control measurements, that can be improved with sequential forecasts of the TSF behaviour. This approach was undertaken to optimise the deposition strategy of the Cerro Vanguardia TSF and expand its life-of-mine (LOM), allowing for tighter construction planning and deferral of construction by several years. This had considerable benefits during the current COVID-19 contingency. Statistical analysis of ongoing operational monitoring data was adequately incorporated into operational design optimisation and to select an adequate level of risk tolerance based on an as low as reasonably practical (ALARP) perspective. Performance-based scenarios were identified and plans for timely decisionmaking were established to forecast reasonable economical/financial planning, and a probability-based events selection to trigger timely operational adjustments.
The paper will present a new pulsation reduction system (PRS) invented by MHWirth. This PRS is in contrast to conventional pulsation damperssuitable to eliminate high-frequency pulsation of reciprocating diaphragm pumps. Brief description of functionality: The new damper is connected to the propelling fluid chamber of the diaphragms. The propelling fluid, a hydraulic oil, is used as a damping medium, converting the pulsation energy described above into heat by throttle effects. This effect is similar to a shock absorber. The paper will also explain the PRS effects, present operational data from field application and address the following benefits by using it in a tailings and storage facility:
This website links to the ICMM Member Companies and their disclosures related to a Church of England request. From the page: The Church of England Pensions Board and the Council on Ethics of the Swedish National Pension Funds wrote to 683 extractive companies, including ICMMs company members, asking them to disclose details of their tailings storage facilities. ICMM is supportive of greater transparency on this important issue. Members have responded to this request and have published details of the tailings storage facilities that they own or operate on their websites. Links are provided for each participating company, where site- and company-specific information can be found
This paper presents the outcomes of a study that utilised predictive methods based on advanced synthetic aperture radar and multispectral data coupled with Google Earth Engine to develop a model for particular TSFs based on historical records, observations, and material types. Google Earth Engine brings the first opportunity to use a systematic and comprehensive combination of radar and visual-infrared satellite data. It was found that the synergy between the two data types could be used to offset the individual ambiguities of each, and the resulting method delivered a predictive dryness probability map and visual moisture/water depth/presence indicators that were able to be verified and made operational almost immediately. On-ground visual records and aerial imagery provided qualitative verification of the approach. The methodology allows TSF operators a free, open source platform with which to monitor and map surface moisture, enabling proactive deposition decision-making to mitigate the risk of tailings dusting. Additional benefits realised include increased data on beach formation, channel and pond location (extent and to some degree depth), improving the accuracy of the TSF water balance. For the particular TSFs studied, the water balance is a critical control from a safety perspective to mitigate potential failure mechanisms, and from an operational perspective to maximise tailings density and water return to the plant.