10 November 2022
High-resolution SkySat imagery of the Williamson Mine tailings dam breach
Posted by Dave Petley
High resolution SkySat imagery of the Williamson Mine tailings dam breach
My good friends at Planet Labs have very kindly captured a high resolution SkySat image of the aftermath of the major Williamson Mine tailings dam breach in Tanzania. I will post further images over the next few days. To start off, the image below shows the site of the breach itself:
The breach that caused the Williamson Mine tailings dam failure. Planet Labs SkySat image, copyright Planet Labs, used with permission. Image captured 9 November 2022 at 11:21 UT.
The breach is large as I noted yesterday. It appears that some of the original tailings wall material, including intact blocks, have been deposited on the downstream edge of the breach, especially on the south side. There appears to be a step in the tailings at the site of the breach, suggesting a lower layer of denser tailings. This indicates that further releases could occur in rainfall.
The tailings that have escaped appear to have been very fluid – note the flow patterns in the sediments.
I can see so signs of any works occurring at the site to manage further releases. Indeed, there are no vehicles or people visible in the image, as far as I can tell.
The SkySat image has also captured the downstream impacts of the tailings dam breach. This is the tailings plume:-
The mine waste plume from the Williamson Mine tailings dam failure. Planet Labs SkySat image, copyright Planet Labs, used with permission. Image captured 9 November 2022 at 11:21 UT.
The images show that the plume hit a water retention structure downstream from the mine, filling the reservoir. Some tailings appear to have overtopped, but most have followed the spillway to the north, inundating the basin of an incised channel. I will try to post further imagery of this area in the coming days.
Reference and acknowledgement
Thanks to Rob Simmon at Planet Labs for acquiring and posting the image.
Planet Team (2022). Planet Application Program Interface: In Space for Life on Earth. San Francisco, CA. https://www.planet.com/
Dave Petley is the Vice-Chancellor of the University of Hull in the United Kingdom. His blog provides commentary and analysis of landslide events occurring worldwide, including the landslides themselves, latest research, and conferences and meetings.
Looks like draw-down embankment failures either side of the breach have reduced the access road width. PS: I wonder if many impoundments like this even have functional dewatering systems. Keeping filters from packing up w/silt and clay is difficult under the best conditions.