When a TSF leaks, it can lead to a range of environmental and safety risks, including:
- Contamination of Water Sources: Leaking tailings can contaminate nearby water sources, including rivers, lakes, and groundwater. This can lead to negative impacts on aquatic life, as well as human health risks.
- Damage to Ecosystems: Leaking tailings can also damage ecosystems and disrupt the balance of local flora and fauna.
- Structural Damage to TSF: When tailings contain too much moisture, it can lead to structural damage in the TSF. This can cause instability, slope failure, and other serious consequences, including damage to infrastructure and the environment, as well as fatalities and other risks.
There have been several TSF leaks in recent years, including:
- Mount Polley Mine, British Columbia, Canada (2014): In August 2014, the tailings dam at the Mount Polley Mine in British Columbia, Canada, failed, releasing millions of cubic meters of tailings and water into nearby rivers and lakes. The failure was attributed to improper monitoring and design of the dam, which allowed the water level to rise to a critical point. The disaster resulted in the loss of fish habitats, contamination of drinking water, and economic impacts on local communities.
- Samarco Mine, Mariana, Brazil (2015): In November 2015, the tailings dam at the Samarco Mine in Mariana, Brazil, failed, releasing millions of cubic meters of tailings and water into nearby rivers and villages. The disaster was attributed to inadequate monitoring and management of the dam, which had been raised several times over the years to increase its capacity. The disaster resulted in the loss of 19 lives, the displacement of thousands of people, and severe environmental impacts.
- Brumadinho Dam, Minas Gerais, Brazil (2019): In January 2019, the tailings dam at the Brumadinho Mine in Minas Gerais, Brazil, failed, releasing millions of cubic meters of tailings and water into nearby rivers and communities. The failure was attributed to inadequate monitoring and management of the dam, which had been classified as stable by the mining company. The disaster resulted in the loss of 270 lives, the displacement of thousands of people, and severe environmental impacts.
These examples highlight the critical importance of proper monitoring and management of tailings storage facilities to ensure their safety and prevent catastrophic failures. It is crucial for mining companies and regulatory authorities to implement robust monitoring and management practices to minimize the risks associated with TSFs and to protect the environment and local communities.
Humidity control as a crucial part of TSFs management
The level of humidity or infiltration inside the wall of tailing support is the most important issue to be controlled because one of the main causes of TSF failure is the liquefaction, which can be static or dynamic, besides other reasons where normally the presence of water is involved.
The traditional tailings deposited in a TSF contain a significant amount of water. Over time, the water in the tailings can percolate through the porous material and create a buildup of pore water pressure within the TSF. If the pore water pressure becomes too high, the occurrence of liquefaction or TSF failure is more probable.
By controlling the humidity within the TSF, mining companies can help to minimize the buildup of pore water pressure and reduce the risk of slope failure. This can be accomplished through a variety of means, such as using liners or barriers to prevent water from entering the TSF, using drainage systems to remove the infiltration of water, or implementing cover systems to reduce evaporation and control the moisture content of the tailings.
Mining companies can also help to prevent the release of harmful contaminants. Contaminants are released when the tailings fill with water, which can happen if they leak into the surrounding environment. By maintaining the moisture content at an appropriate level, companies can protect their communities and the environment.
Tools and Methods to Monitor Humidity in TSFs
To prevent TSF leaks, it is critical to measure or monitor humidity levels in the tailings. There are several methods and tools that can be used to accomplish this, such as:
- Soil Moisture Sensors or Piezometers can be used to measure the water content of the tailings in the TSF. These sensors can be installed in wells at different depths within the TSF to provide a more accurate picture of the moisture content and to identify potential hotspots.
- Automated Weather Stations can be used to monitor environmental conditions within and around the TSF, including temperature, humidity, wind speed, and precipitation.
- Inclinometers can be used to measure the deformation or displacement of the TSF wall tailing support. By tracking changes, mining companies can identify potential instability caused by high deformation inside the wall tailing support.
- Satellite Monitoring can be used for digital monitoring of subsidence or surface deformation with the highest precision. It can also be used for optical or imagery monitoring to identify areas of potential risk or to observe changes in the environment around the TSF. For instance, changes in vegetation cover or surface water flow patterns can indicate areas of excess moisture within or outside the TSF.
- Regular visual inspections of the TSF can also help to identify potential issues related to moisture content. Inspectors can look for signs of erosion, cracking, or other indications of instability caused by excess moisture.
- Airborne Ground Penetrating Radar (GPR) is a non-invasive methodology that can be used to monitor the humidity inside the wall tailing support. It provides wide coverage, high resolution, and high-depth penetration, making it an effective real-time monitoring tool.
Airborne GPR as an Efficient Method for Monitoring Humidity
Airborne ground-penetrating radar (GPR) is a highly effective method for monitoring humidity in tailings storage facilities (TSFs), especially for larger or more remote sites. By offering high-resolution images of the subsurface structure of the TSF, airborne GPR can detect potential risks at an early stage, thus preventing catastrophic failures. Overall, the use of airborne GPR is an invaluable tool in the ongoing effort to ensure the safety and integrity of TSFs.
By utilizing airborne GPR, it is possible to obtain a range of benefits, such as:
- Non-invasive: Airborne GPR is a non-invasive method for monitoring moisture content in the TSF. It does not require drilling or excavation, which can be time-consuming and costly and can also disturb the integrity of the TSF.
- Wide Coverage Area: Airborne GPR can cover a large area in a relatively short amount of time, making it well-suited for monitoring large TSFs. This can also help to identify areas of potential risk quickly and efficiently.
- High Resolution: Airborne GPR can provide high-resolution images of the subsurface structure of the TSF, which can help to identify potential hotspots or areas of excess moisture.
- Depth Penetration: Airborne GPR can penetrate depths of several meters, which can provide a more comprehensive picture of the moisture content of the TSF. This can be particularly useful for identifying potential risks in deeper layers of the TSF.
- Real-time Monitoring: Airborne GPR can provide real-time monitoring of moisture content, which can help to identify changes in moisture content quickly and accurately. This can be particularly useful for identifying potential risks during periods of heavy precipitation or other environmental events.
All the functionalities mentioned above were successfully utilized by a mining company during the two-week project in Chile (see graphics below).
They equipped a DJI M600Pro with a GPR RadarTeam SE70 and UgCS with True Terrain Following (TTF), allowing the drone to follow the terrain with very high precision at low altitudes using an altimeter sensor to manage a Humidity Analysis at Tailings Dam.
By utilizing GPR technology, it was possible to enhance the monitoring and analysis of Tailings Dam Walls. With its ability to generate high-resolution images of subsurface materials, GPR has been instrumental in identifying humidity-related anomalies and facilitating ongoing wall stability monitoring. Monthly assessments of humidity levels in relation to the Tailings Dam Wall have enabled early identification of potential risks and hazards, which has led to a more secure and streamlined mining operation.
Installing GPR on a drone, surveying can be conducted more efficiently, cost-effectively, and safely, as it allows the user to see through the surface of the ground, rocks, and hazardous environments without endangering staff. This innovative technology provides an additional solution to improve surveying operations.