Williamson Diamond may face NEMC’s wrath over facility breach

Dar es Salaam. The ministry of minerals has distanced itself from the Williamson Diamond mine’s Tailings Storage Facility (TSF) breach, saying if acts of negligence have been identified, then the country’s environmental watchdog NEMC will enforce its laws.

This was said by deputy minister for minerals Steven Kiruswa after The Citizen had inquired about his reaction following NEMC’s findings, which indicate signs of negligence subsequent to early warning for infrastructure failures.

“The ministry is responsible for developing the sector and making sure all practitioners observe the laws of the land. A ministerial team was formed, it has its recommendations, and if you want more information, then contact the minister,” he explained.

He added: “But if there is anything related to the environment, NEMC is the right organ; they will execute their powers as stipulated in the law, they might even fine the party that did not follow stipulated procedures.”

However, efforts to reach the minerals minister, Dr Doto Biteko, proved futile yesterday.

But, three days ago, The Citizen’s sister newspaper, Mwananchi, quoted Dr Samuel Gwamaka, the NEMC’s director general, as saying: “The failure’s prior signs were already there, but they never acted accordingly.”

Furthermore, Dr Gwamaka noted another neglect, saying: “They never constructed a facility that would control any failure threat, but next week, we are going to put in public our final findings, which will instigate legal action against them.”

Last month, The Citizen revealed that the breach, which caused flooding, would have been discovered if the facility’s standard best practice of “observational method” (OM) had been followed.

Ms Lindsay Bowker, an executive director for the World Mine Tailings Failures (WMTF), exclusively explained that Interferometric Synthetic Aperture Radar (InSAR) findings covered a period from June to November 2022, when the failure occurred, and proved early signs of deformity.

“The accelerated deformation that caused the facility to fail began immediately on the resumption of expanded depositions, in fact, five months prior to failure.” “Value.Space’s InSAR has indicated 15 areas on the TSF that have notable deformation,” she observed.

“These 15 deformed conditions were detectable through normal TSF best practices of observational methods throughout the life of the facility from design to closure,” she explained.

According to the expert, InSAR technology uses satellite images for monitoring assets such as the Williamson mine and has reliably shown subsidence on tailings containment and dormant waste piles, thus providing an early indication of slope failure that would allow the monitoring of TSF’ stability.

Media information indicated that the high level of production through bulk mining generates a higher rate of deposition of tailings and perhaps a different character that was not assumed in the original design.

Therefore, an assessment related to the facility’s capacity to manage an expanded volume of tailings was vital, as it could have shown whether the already constructed facility could absorb a faster rate of deposition. Moreover, in its statement regarding the failure, Petra Diamonds’ London office, which owns 75 percent of the mine’s share, said there was a low risk of further breaches of the TSF or a breach of the New Almasi water dam.

Furthermore, Petra noted that the failure mechanism was the subsidence of a portion of the eastern wall of the TSF by around 1.5m, which enabled the water to crest the wall, initiating the breach, though the root cause of the subsidence is not yet determined.

“This work will be undertaken by an independent company specializing in tailings, dam design, and management. The cost and timing of the investigation will be available after a detailed scoping process is completed, but preliminary indications suggest that this exercise will take between six and twelve months,” according to the statement.