South Australian Mineral Resources Minister Tom Koutsantonis says there is no need for BHP Billiton to submit a new environment impact statement for its Olympic Dam mine expansion plan in the state's outback.
The company has been given an extension to its indenture agreement until October 2016, giving it more time to decide whether to go ahead with turning its underground mine into a vast open pit.
Over the next four years, BHP has promised to spend $650 million in SA on mining technology and rescoping its expansion plan.
Mr Koutsantonis says the current environment impact statement (EIS) covers any use of a heap leaching technique the company will now consider for ore extraction.
"BHP had foreseen that in the next five to six to seven years they may have been switching to this technique," he said.
"What they'd always proposed in the negotiations with us and the Commonwealth was ...
the mine life of this ore body would be so long that they would eventually switch technologies to a lower-cost option.
"That lower-cost option was going to be heap leaching.
Now they do heap leaching in others part of the world but not for multiple ore bodies." 'Two sentences' South Australian Greens leader Mark Parnell disagrees and thinks the impact statement needs to be reworked because it makes scant mention of any acid leaching.
Holding a copy of the EIS, Mr Parnell told reporters: "Here is the 7,000 pages of the EIS and the supporting documentation.
What it shows is that there are two sentences where BHP Billiton - in a thought bubble - says they might think about it in the future but they are certainly not seeking approval for an acid leaching mine at Olympic Dam, so for the minister to say that it's covered by the EIS is just plain wrong," he said.
"There's nothing in the EIS, the longest document ever produced in this state, about pouring acid over piles of ore so they do need to go back to the drawing board." When he was asked about the EIS, South Australian Premier Jay Weatherill said any future mine upgrade would face the strictest of environmental standards but he was unable to say if current environmental approvals would have to change.
"This was contemplated within the EIS but no doubt there are particular discrete approvals that will be attached to particular parts of the mining operation when it gets the go-ahead, so they're all matters that will be attended to in time," he told reporters.
"But the overarching principle is this; this expansion will operate in accordance with the highest environmental standards."