Tailings Storage Facilities (TSFs) are critical to the mining industry, for containment of by-products generated from the extraction of minerals. These by-products, or tailings, include a mix of ground rock, process water, and chemical reagents. Due to their extensive size and the nature of the materials they contain, TSFs are among the largest engineered structures in the world and represent significant geo-hazard risks if not properly managed.
Geo-Hazard Risks Defined
Geo-hazards affecting TSFs can be natural or human-induced and pose considerable threats to the integrity and safety of these facilities. Common geo-hazards include:
- Earthquakes: The seismic activity can destabilize the foundation and slopes of TSFs, leading to potential structural failure.
- Landslides: Triggered by heavy rainfall, soil erosion, or changes in water levels, landslides can breach dams and lead to catastrophic failures.
- Floods: TSFs can be overwhelmed by excessive rainfall or storm surges, raising the risk of structural damage and overflow.
Case Studies Highlighting Geo-Hazard Impacts
Heavy rainfall triggered a catastrophic failure of the 980 Gou Tailings Dam due to slope instability and inadequate drainage systems. The failure resulted in the tragic loss of 277 lives, with 33 individuals suffering injuries. Beyond the immediate human cost, the event caused extensive property damage and environmental contamination. The dam breach released millions of cubic meters of toxic tailings, flooding downstream areas and leading to significant economic losses estimated in the millions of dollars.
The collapse of the dam at the Córrego do Feijão iron ore mine in Bruma Dinho was another stark reminder of the potential for structural failure in TSFs. Investigations pointed to liquefaction of the tailing's material as a key factor in the dam's failure. The breach released a massive flow of mining waste, claiming at least 259 lives and causing irreparable environmental damage, including the pollution of hundreds of kilometers of rivers downstream. The volume of tailings released was estimated to be about 12 million cubic meters, which swept away buildings, infrastructure, and vegetation, rendering vast areas uninhabitable.
These disasters highlight the need for robust risk assessments that consider extreme weather conditions and the implementation of comprehensive emergency response strategies. These also underscore the need of real-time monitoring of TSFs, using technologies such as UAV and WebGIS for early detection of potential failures, and reinforces the importance of designing dams to withstand worst-case scenarios, including the prevention of liquefaction.
Read more: Tailing Dam Safety: The Multisensor Approach in Mining
Risk Assessment Techniques
A comprehensive risk assessment is vital, considering the complex nature of TSFs. The utilization of advanced techniques, such as the innovative WebGIS-Based UAV Method for analyzing tailings ponds through UAV oblique photography, offers new avenues for assessing changes in storage capacity and identifying potential dam failure risks.
Also, the three-dimensional risk matrix that evaluates failure probability, event intensity, and exposure of failure-bearing bodies facilitates a nuanced risk categorization and management approach.
Mitigation Strategies for Geo-Hazard Risks
Mitigating the risks associated with TSFs demands a comprehensive and multi-disciplinary approach, focusing on the following key measures:
- Strengthening Dams: This includes employing design principles that account for the worst-case scenarios of geo-hazard events, such as earthquakes and floods. Materials used in construction must be carefully selected and tested to ensure their resilience against such events, coupled with regular maintenance to address any signs of wear or vulnerability.
- Emergency Preparedness: The implementation of comprehensive evacuation plans and early warning systems are paramount. These systems must be designed to provide timely alerts to the facility operators and surrounding communities in case of an impending failure. Regular drills and the education of local populations about these plans are essential to ensure preparedness for any emergency.
- Continuous Monitoring: Continuous monitoring of the facilities through regular inspections, geotechnical instrumentation, and real-time monitoring technologies. This includes deploying sensors and UAV technology for the early detection of potential issues such as cracks, leaks, or structural weaknesses. Data collected from these monitoring activities should be analyzed promptly to allow for immediate action when necessary, using platforms like Proqio.
- Risk-Informed Decision-Making: Integrating comprehensive risk assessments into operational decisions ensures that TSF management is always aligned with the latest understanding of potential hazards. This involves the initial design and construction phases and the operational and closure stages of the TSF lifecycle. Decisions regarding the management of the tailings, the height and structure of the dams, and the response to weather events must all be informed by a thorough understanding of the risks involved.
Read more: A Guide on Structural Health Monitoring (SHM)
Encardio Rite specializes in advanced geohazard monitoring solutions for mines and tailings dams, focusing on safety and accident prevention through ground movement surveillance. We integrate metasensing, data collection (including remote sensing via InSAR, optical, thermal, multispectral, and hyperspectral imagery, along with UAVs, LIDAR, laser scanning, radar, automatic total stations, and GNSS for surveying and 3D modeling), surface and subsurface sensors (fiber optics, environmental, and geotechnical instruments), and seamless data integration from various sources for dynamic visualization and analysis through Proqio. This facilitates movement/change detection, digital twin creation, and GIS integration, supported by an early warning system and risk assessment aligned with government standards, for continuous monitoring of critical parameters (water level/pressure, lateral movement, inclination, deformation, settlement, load/force, strain, vibration).Our multi-sensor system is deployable through a single borehole, monitors pore pressure, lateral displacement, and settlement, improving safety and operational efficiency by minimizing borehole requirements.
By adhering to mitigation strategies and continuous monitoring, mining operations can significantly reduce the risks posed by geo-hazards to TSFs, thereby protecting human lives, the environment, and the integrity of mining operations.