MAC: Mines and Communities

New Ok Tedi crisis

Published by MAC on 2005-12-22

New Ok Tedi crisis


22nd December 2005

Sulphide-bearing tailings posing threat

SULPHIDE-bearing tailings from the Ok Tedi mine have begun to turn into acid on the banks of the Middle Fly River, confronting thousands of villagers with a major environmental crisis.

Company executives first noticed the acid rock drainage in February - including dead vegetation patches the size of football fields - and government officials were immediately notified.

This development creates the prospect of worsening environmental impacts following dieback problems affecting 1,500 sq km of forests that could persist for some 200 years.

Overseas experts suggest severe acid rock drainage could be an even greater long-term environmental hazard that could have devastating impacts on the local ecology without preventive measures.

Ok Tedi Mining Ltd managing director Keith Faulkner told The National numerous studies are being carried out on ways to tackle ARD, and that mitigation costs could be as high as US$100 million.

These options will be explained to villagers next year so they can decide if mining should be halted or allowed to continue, a dilemma they had also faced five years ago under the previous operator, BHP Billiton.

Tailings containing sulphide are already present in a wide area, where they can react with oxygen and water and turn into acid although water in the Fly River remains safe to drink.

Options to tackle the looming ARD crisis include burial of sulphides below the water table, and extraction of sulphides at the process plant prior to tailings disposal.

Early mine closure would adversely affect the PNG economy since copper and gold exports from OTML last year were worth K2.06 billion or 25.7% of PNG's total exports.

Taxes, mining levies and royalties paid to National and Provincial Governments by OTML amounted to K265.6 million.

Ironically, last year was OTML's most profitable in its 31-year history. An even better result is anticipated this year because of high copper and gold prices.

Expert consultants over the years had believed deposition of limestone in the Ok Tedi and Fly River would neutralise sulphide materials and stop the formation of acid.

Mr Faulkner said significant environmental damage from ARD was only likely under certain climatic conditions such as during long dry spells caused by 'El Nino' weather patterns.

He told National Government Ministers at a recent mine closure workshops that the present situation "turns out to be far more complex, far more difficult" than the situation when BHP Billiton left the project.

Environmental modelling indicated the deleterious effects of sedimentation and dieback, especially in the Middle Fly, would last longer, possibly for 200 years.

Mr Faulkner described the situation as "a bitter paradox - the dredged sands that have reduced the die-back, are presenting long-term management problems with acid rock drainage from sulphur content in the sands and the potential to release copper and other metals into the river, particularly under certain climatic conditions."

OTML's environmental manager Jim Venese said problems had occurred because sulphur content in the ores had risen from two to four per cent over the past three years and could go to seven per cent in coming years.

Villages along the Middle Fly confirmed seeing plants and vegetation dying in early July, but said they only understood what was happening when OTML informed them about the impact of ARD.

"We were wondering why the plants and grass were dying and sands had turned colour to dark brown," Earnest Kaima, a village elder, told The National.

Mr Faulkner said: "We need to understand the costs and benefits of any mitigation strategy so that we know that implementing any vastly expensive strategy is actually worthwhile," he told the recent mine closure workshop.

"Ultimately we need to strike the right balance of those competing environmental, social and economic factors. That's not something that OTML can do on its own."

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