The Rio Tinto subsidiary expects the pit extension will take six years to mine.
The land for the extension is within the company’s existing tenures while the project will increase efficiency by uncovering coal with a low strip ratio.
In December, the company held community information sessions on the proposal at Bulga, Maison Dieu, Warkworth and Jerrys Plains.
"We're proud of our long history in the Hunter Valley, and we're committed to the future,” HVO general manager operations Graham Gageler said.
“Our current plans are focused on our existing assets and tenures, and we will continue to consult widely with the community as we always have."
Coal & Allied lodged an application to modify the existing development consent with the state government last week.
Rio owns 76% of the Australia-listed company.
