Jagersfontein - what do we know about the tailings dam failure?

There is an investigation, so we shall find out what caused the collapse at #Jagersfontein when the investigation reports. The Sowetan is reporting that the Department of Water & Sanitation (DWS) is doing an investigation, while Richard Spoor is tweeting that the Department of Mineral Resources & Energy (DMRE) has jurisdiction, as the 2009 judgement that put the tailings dam owned by Jagersfontein Developments outside the Mineral and Petroleum Resources Development Act (?#MPRDA?)?did not refer to the Mine Health and Safety Act ( #MHSA ), which has a different definition and explicitly includes #tailings (mine means, when used as a noun, any borehole, or excavation, in any tailings... made for the purpose of searching for or winning a · mineral, whether it is being worked or not).

While we wait for the investigation report, there are some interesting facts that various people have pointed out. The below is a summary of fascinating work done by others:

Dave Petley, Vice-Chancellor of the University of Hull, blogs on landslides for the American Geophysical Union, reports that in addition to the main breach, there are several other locations where there appears to have been substantial erosion of the dam walls - including one close to the western cell which has not breached, and one on the eastern (breached) cell away from the main breach.

Richard Spoor points out that efforts have been made in the past to buttress the northern wall (far side from the breach).

Petley has also observed that between February 2019 and February 2021, the southeastern wall of the tailings dam (where the breach occurred) was thickened substantially, compared to other walls

This appears on first inspection to have been what might be described as buttressing on the downstream side.?No explanation has been provided as yet as to why this occurred

Carin Bosman tweeted the dam breach analysis from 2020, which shows where the tailings would go if the dam failed (spoiler: that's where they went)

CGG Minerals and Mining have done a detailed analysis of satellite imagery of the site, and they have shown a zone of upward movement in the south-central part of the site, and downward movement in the south-east part of the site. Petley points out that

The junction between the two is close to the apparent failure point

If you look at the CGG's high res satellite image (their post's slide 3 or Petley's first diagram in this post), you can see that the breach occurred not quite at the southeast corner of the current tailings dam, but actually near to the southeast corner of the original tailings dam (from before reprocessing started). Or to put it another way, the failure point is close to the junction between the base of the old tailings dam (near the zone of upward movement) and the base of the eastward extension of the tailings dam (near the zone of downward movement).

Spoor has also tracked recent regulatory developments, with the DWS directing Jagersfontein Developments to stop dumping on the tailings dam in December 2020, and allowing its use to continue again in June 2021. Jagersfontein Developments (i.e. the tailings dam) was then sold by Reniet to Stargem in April 2022.

Edit:

A number of people such as TSF Risk Solution's Denzyl Pearse, and Charles MacRobert of Stellenbosch university have posted showing the growing size of the process water pool - see the 3 comparative images in MacRobert's post - on top of the tailings dam, and associated risks.

John Metzger has shown there are overtopping stains on all benches across the southern and eastern corner (indicating that process water or tailings spilled out of the tailings dam), in January 2021 - which was during the period when Jagersfontein Developments were not meant to be depositing tailings (although also the rainy season). Metzger has also detail of an overtopping event on 9 January.