Energy Resources of Australia has formally begun its statutory approvals process for the proposed Ranger 3 Deeps underground uranium mine.
It comes after the miner was accused of expanding said operations without environmental assessments.
ERA is investing around $120 million to construct an exploration decline to define its existing resource.
Construction of the decline began in May last year, with closed space drilling scheduled to commence in quarter three of this year.
The miner has also allocated an additional $57 million for a prefeasibility study into the development of an underground mine.