The company that designed the Stockton Plateau Hydro Scheme is applying for a six-year extension to its resource consents.
In 2010, Hydro Developments Ltd (HDL) developed the original design to treat acid run-off from coal waste dumps on the massive plateau in Buller, use the water to generate electricity and pipe it, once highly-diluted, out to sea.
The 10-year-resource consents are about to lapse and the company is asking the West Coast Regional Council and Buller District Council to extend them.
The consents include a coastal permit, and an assortment of land and water-use consents to build reservoirs, roads and pipelines.
Under the RMA, the councils will have to consider whether HDL has made substantial progress or efforts to use the consent.
HDL director John Easther said the former owner of the Stockton Mine, Solid Energy, had expected to build the hydro-scheme within two or three years with Crown support.
However, progress was delayed when the State-owned enterprise was first placed in voluntary administration then later sold.
As part of the deal, the Crown accepted the historic liabilities for the effects of its old coal waste dumps on freshwater, with the new owners Bathurst Mining managing the rehabilitation of the plateau, under instructions from Treasury.
"Treasury continues to work on the project as and when its resources permit," Mr Easther said.
"It's basically sitting on someone's desk waiting for attention."
Those delays were understandable, he said.
"This all came about at the time the government changed and Treasury had a whole raft of major projects to get off the ground."
The mine run-off was currently treated by lime dosing to reduce its acidity.
But that was costly, and not viable long-term, Mr Easther said.
"The benefit of the hydro scheme is that it will generate not just power but revenue to offset the cost of the rehab."
Despite the complications, progress had been made on the project, on access roads, surface water monitoring, geo-tech drilling for the planned reservoirs, and weed control, he said.
"Currently there is no other affordable, certain or viable pathway for the rehabilitation of the Stockton Plateau, once mining ceases."
West Coast Regional Council consents manager, Heather McKay, said she expected the HDL application to be processed within 20 working days and it was unlikely to be publicly notified.
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