Glencore's plans to expand its Mangoola Coal Mine near Muswellbrook

Federal environment minister Sussan Ley has approved the development of a new open cut coal pit at the Mangoola Coal Mine west of Muswellbrook.

The mine had already been approved by the NSW Independent Planning Commission in April this year.

The proposed expansion involves extending the existing open cut mine to extract an additional 52 mega tonnes of coal.

The expansion will add an additional eight years to the operational lifespan of the mine, however the time frame for the approval extends for 19 years to December 2040 to account for construction and rehabilitation of the mine site.

In approving the mine, Ms Ley found "the available evidence indicates that a decision to approve the proposed action would be unlikely to lead to an increase in global average surface temperatures."

Ms Ley stated the approval or refusal of the proposed action would not affect global demand for coal overall and that there are sufficient alternative sources of coal to supply future demand in projected future scenarios.

"The rejection of the proposed action is unlikely to have an impact on total global coal consumption, or to impact the price of coal," Ms Ley continued.

The approval also considered the 'significant impact' on water resources and threatened species in the area, including the regent honeyeater, swift parrot and grey-headed flying-fox, and attached conditions for the mine operator Glencore to adhere to.

The conditions will require Glencore to monitor the quality of surface water and prepare a stream monitoring program for the Hunter river discharge point as well as requiring the company to offset the destruction of habitat for the threatened species.

In a statement, Glencore said it was pleased with the decision to approve its Mangoola project and would look to finalise remaining approvals to enable work to start.

"The project will not change current approved maximum production levels or train movements, and will use existing major infrastructure, such as the coal preparation plant, rail loop, workshop, emplacement areas and administration facilities," the statement said.

Muswellbrook Shire Council has previously voiced its opposition to the project when it came before the NSW Independent Planning Commission (IPC) earlier this year.

"Muswellbrook Shire Council has a history of working collaboratively with coal 40 mines in its local government area, and it's done that to achieve community outcomes that are beneficial to the community; however, the time has been reached, in the opinion of the council, with the Continued Operations Project that enough is enough," barrister Craig Leggatt SC said at the time.

At the time, Glencore issued a statement which said the company was "surprised and disappointed" by Muswellbrook Council's decision to oppose the project.

Muswellbrook Shire Council has been contacted for comment in relation to the granting of federal environmental approval for the Mangoola coal mine expansion plans.