Civil engineers use public satellite images to study why the Jagersfontein dam failed
- Wits University
Study by civil engineers at Wits University finds that the history of the Jagersfontein dam deviates from best engineering practice.
On 11 September 2022, a diamond mine waste storage facility, known as a tailings dam, failed in the town of Jagersfontein in the Free State province of South Africa. In the failure, one person was killed and multiple homes destroyed.
Tailings are the finely ground leftovers that remain after valuable metals are removed from rock ore. Tailings are generally transported jointly with water and deposited in a tailings dam for storage.
Now, six months later in 2023, civil engineers at the University of the Witwatersrand, Johannesburg (Wits), have used public satellite and aerial imagery in a study to investigate the history of the Jagersfontein dam.
Satellite images show what went wrong
Sources of public satellite images used in the study included Google Earth Pro and the Sentinel-2 and Landsat 8 satellite missions. Additionally, some of the immediate consequences of the failure were assessed using commercial satellite images.
Dr Luis Torres-Cruz and Mr Christopher O'Donovan in the School of Civil and Environmental Engineering at Wits authored the paper, which was published in the journal Scientific Reports on 5 April 2023.
The study found that the history of the Jagersfontein dam deviates from best engineering practice. The deviations include mine waste deposition from predominantly one side of the dam, erosion gullies on the dam wall, and significant amounts of ponded water at times positioned against the retaining structure.
Based on the analysed images, the study hypothesises that percolation of water through the dam, followed by external erosion, ultimately triggered instability.
“We expect our paper to be useful to those interested in understanding how this tragic event came to be and also to help prevent future failures,” says Torres-Cruz, corresponding author and a Senior Lecturer in the School of Civil and Environmental Engineering, who specialises in geotechnical aspects of tailings