ERA has already halted the processing plant at Ranger for up to 12 weeks to try to prevent water levels at the tailings dam from breaching operating limits.

 

But after continued heavy rains the dam level has already exceeded its wet-season limit of 52.5 metres, requiring the Northern Territory Minister for Resources to grant ERA a temporary increase in the limit to 53 metres, the maximum design level.

 

The traditional owners in the area want the Rio Tinto-controlled ERA to implement its contingency plan of pumping water from the dam into the pit to eliminate the risk of radioactively contaminated waste water overflowing into Kakadu National Park.

 

“We think they should trigger the plan,” said Justin O’Brien, executive officer at Gundjeihmi Aboriginal Corporation, which represents the Mirarr traditional owners. “To them it’s a last resort but these are desperate times.”

 

According to the Office of the Supervising Scientist, the government agency responsible for overseeing Ranger, yesterday the level of the tailings dam was at 52.58 metres.

 

“The regulator has allowed ERA to utilise the surge capacity between 52.5 metres and 53 metres for the remainder of the wet season,” supervising scientist Alan Hughes told The Australian Financial Review .

 

The temporary order allows ERA to put off having to start transferring process water to Pit No. 3 until the dam level approaches 53 metres.

 

ERA said it still had capacity to accommodate more rainfall in the tailings dam, which is being monitored regularly.

 

Pumping water into the pit “is dependent upon further significant rainfall,” the company said, adding there was no change to the 12-week suspension of the plant.

 

Tropical cyclone Carlos has combined with the La Nina effect to make the 2010-11 wet season in Darwin the wettest on record, with two months still to go.

 

The 12-week shutdown, which ERA announced in late January, means the miner’s full-year output is unlikely to improve from last year’s 3793 tonnes, which was 28 per cent down on 2009. It is also eating into the company’s ability to benefit from the recent rise in spot prices for uranium oxide.

 

While a 12-week shutdown was expected to be the worst-case scenario for ERA, Mr O’Brien suggested that a longer stoppage could be on the cards.

 

“With or without rain they have a full tailings dam when they go into the dry season, whenever that is, so the issue of them returning to production on May 1 I think has been put very much in jeopardy,” he said from Jabiru, about 10  kilometres from Ranger.

 

The concerns about water management at Ranger are also playing into the hands of opponents to ERA’s plans to extend the life of the mine through its $250 million heap leach project and the Ranger Deeps proposal, which would add an underground operation to access another 34,000 tonnes of uranium oxide.

 

ERA’s board is due to make a decision on whether to proceed with an exploration decline for the Ranger Deeps project this half after completing a feasibility study last year.

 

But UBS mining analyst Glyn Lawcock has suggested the board is dragging its feet on the decision because it doesn’t have the support of the traditional owners.

 

Technically ERA does not need the backing of the Mirarr to proceed with Ranger Deeps because it lies on the same Ranger lease. But Rio Tinto’s social responsibility ethics could prevent it from going ahead without indigenous backing, Mr Lawcock said.

 

ERA said it “continues to maintain an open, honest and productive dialogue with the traditional owners on a range of issues relating to its operations, including the Ranger 3 Deeps exploration decline.”