BHP Billiton is planning to build a new underground thermal coal mine near Gunnedah in the fertile Liverpool Plains region of northern New South Wales (NSW), Australia.

The Caroona mine, which is considered as the nation’s largest underground coal mine, is expected to export 10 million tons of thermal coal a year.

Papers for the underground mine plan have also been submitted by the company to the Federal Environment Department.

Expected to operate for 30 years, the mine would employ up to 400 people, with about 600 positions to be filled during peak construction periods, the company noted.

Mine construction is anticipated to commence in 2018 if approved, with production slated for 2021.

The Australian cited BHP NSW thermal coal asset president Peter Sharpe as saying, "The preliminary environmental studies undertaken for the Gateway submission indicate that the proposed underground mine will not impact the alluvial irrigation aquifers essential for agricultural production in the area."

The diversified resources company, however, is facing significant opposition from the local community, as the new mine would impact the region’s water supplies.