Using InSAR to Predict Tailings Dam Failures
Cadia Valley, New South Wales, Australia
Highlights
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The Cadia Valley Northern Tailings Storage Facility (NTSF) forms part of a gold and copper mining processing complex. A section of the tailings am collapsed on 9th March 2018, releasing some tailings into the adjacent southern TSF.​
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Fortunately, the spill was contained and there were no casualties. We investigated how early the collapse could have been predicted had the dam been monitored regularly using satellite SAR data.
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With sufficient warning time, the collapse may have been avoidable with proactive remedial measures.
The Cadia Valley Northern Tailings Storage Facility (NTSF) is part of a gold and copper mining complex. On 9th March 2018, a section of the tailings dam collapsed, causing a release of tailings into the adjacent Southern TSF. Fortunately, the spill was contained, and no casualties occurred. However, the incident raised questions about whether the collapse could have been predicted and prevented through regular satellite-based monitoring.
The Challenge: Could the Collapse Have Been Prevented?
Geofem investigated whether regular satellite Synthetic Aperture Radar (SAR) monitoring could have provided early warning signs of the collapse. In this case, proactive measures might have been taken to avoid the disaster. The study focused on using Interferometric SAR (InSAR) data to detect ground movement over time and determine if the collapse could have been predicted.
Depending on the alert thresholds set for velocity or acceleration, operators of the NTSF could have been warned about the increasing ground movement one to two months before the collapse. This early warning would have given the operators enough time to investigate the issue on-site and potentially implement stabilisation measures to prevent the failure.
The Solution: InSAR Analysis to Track Displacement
InSAR analysis of Sentinel-1 descending SAR data revealed ground movement at the site of the collapse. The mean annual velocity was calculated, with red points indicating the highest velocities ranging from 38 to 45 mm/year at the exact location of the collapse, as shown by an optical satellite image superimposed on the data. A plot of displacement versus time showed that the ground had been shifting consistently for two years, with a significant acceleration occurring after 8th January 2018. During this period, the velocity increased from an average of 45 mm/year to 90 mm/year by February 2018—double the previous rate. By 25th February 2018, the velocity surged to 214 mm/year, more than doubling again.
The Benefits: Early Warning and Proactive Measures
Conclusion: The Importance of Regular Monitoring
This case study highlights the importance of regular satellite-based monitoring, such as InSAR, for detecting early warning signs of ground movement. With sufficient data and proactive intervention, the Cadia Valley dam collapse may have been avoidable. Monitoring solutions like these offer a cost-effective way to safeguard critical infrastructure, ensuring that potential hazards are identified early and managed effectively.
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For more information on how satellite monitoring can help prevent structural failures, contact Geofem today.
