On November 7, a part of the japanese wall of Williamson’s tailing dam collapsed, releasing a complete of 12.8 million cubic metres of water and tailings materials that flooded close by areas.
There have been no accidents or fatalities and the mine pit was unaffected, Petra mentioned. It added that water and tailings materials samples taken by the Tanzanian Authorities Chemist Laboratory Authority didn’t discover harmful chemical substances and those detected have been inside regular parameters.
Petra, which additionally operates three diamond mines in South Africa, mentioned its Tanzanian subsidiary, Williamson Diamonds (WDL), has constructed since an preliminary 6-metre-high wall to shut the breached wall space.
As a precautionary measure, WDL has additionally put up containment partitions upstream and downstream of the New Alamasi water dam, whereas assist for facility’s new wall is beneath means.
Varied diversion trenches are additionally being constructed to forestall any build-up of water and to allow rainwater to movement into the encircling rivers and streams, Petra mentioned.
As much as one-year wait
In a preliminary evaluation, each Petra’s and impartial exterior specialists concluded that the failure was the results of a subsidence of a portion of the TFS’ East wall measuring round 1.5 metres. This enabled water to crest the wall, initiating the breach.
“The basis explanation for the subsidence has not been decided and would require a forensic geotechnical investigation to be accomplished,” Petra mentioned.
“This work shall be undertaken by an impartial firm specializing in tailings dam design and administration,” it added.
Value and timing of the investigation shall be accessible after an in depth scoping course of is accomplished, however the miner mentioned preliminary estimations level to between six and 12 months.
The corporate mentioned that, in gentle of the failure of the present facility, the design of the brand new TSF is at present beneath overview, and is anticipated to be finalized in February 2023.
Petra warned the brand new TSF will take longer than initially anticipated to grow to be operable. In parallel, an choice of repairing and utilizing the present TSF can also be being explored as a long-term answer, however that is topic to the result of the geotechnical investigation.
Petra, which owns 75% of Williamson, mentioned it was in talks with the federal government of Tanzania, which owns 25% of the diamond mine, on choices for monetary assist through the manufacturing halt.
One of many choices proposed by the corporate is the discharge and sale of a 71,654 carat diamond parcel seized by Tanzanian authorities in 2017.
On the time, Petra needed to halt operations at Williamson, the supply of the confiscated diamonds, as native authorities claimed the corporate was undervaluing its exports, which the miner has denied.
The 2 events reached an settlement in December 2021, with the Tanzania authorities agreeing to launch the proceeds of the parcel sale to the corporate.
Operations at Williamson have been halted for months final 12 months attributable to a decline in diamond costs. Throughout this time, the mine was topic to quite a few incidences of unlawful mining, and accusations of human rights abuses by safety guards attempting to maintain intruders at bay.
Petra investigated the claims and find yourself reaching a $6 million settlement.