Petra Diamonds shuts Tanzanian mine for three months following tailings dam breach

PETRA Diamonds said its Williamson mine in Tanzania would be shut for up to three months while it constructed a new tailings storage facility (TSF). This was following a breach of the mines existing tailings facilities on November 7.

The UK-listed miner also said some of the tailings from the breach had run into a tributary although the flow had been mainly water and had been contained by “the topograhy”. Petra previously reported that the eastern wall of the TSF had been breached resulting in flooding away from the mine pit into “certain areas outside of the mine lease area”.

Drawing on an initial assessment, it said today satellite imagery indicated that the main portion of the tailings were contained by a newly built water dam in the mining lease to the north east of the TSF. The tributary affected was to the north of the water dam.

A total of 13 dwellings were affected by the breach but Petra confirmed there had been no loss of life. Three people received minor injuries and had been treated. “Remediation plans” were also implemented by the company.

“Extensive and ongoing engagement with communities will continue to take place, together with the Government, to ensure that key stakeholders are kept appraised of WDL’s (Williamson Diamonds Ltd) response, including planned remediation activities,” Petra said.

It added that planning was underway to bring a new TSF which had already been under construction into operation. This requires construction of a new wall on the boundary of the failed TSF.

“A preliminary estimate suggests that production will be temporarily suspended for up to three months until the new TSF has been commissioned,” said Petra. As an interim measure, the company had brought forward planned maintenance and accelerated waste stripping to minimise the impact of lost production.

This comes at an unfortunate time for Williamson which was reopened last year following a decline in diamond prices forced it into mothballs. During this time, Williamson was subject to numerous incidences of illegal mining which local security sought violent means to quell.

A new social compact signed with Petra, coinciding with an improvement in diamond prices and a prior restructuring of Petra’s balance sheet, enabled the company to reopen Williamson after considering its sale for a period.