Environmentalists are warning a coal mining company's proposal to reopen and extend a dormant underground operation in New South Wales could cause "significant and unpredictable" damage.
Centennial Coal's Angus Place Colliery, near Lithgow in the Blue Mountains, has been in care and maintenance since 2015.
The company now wants to draw on the fossil fuels left there to supply what is set to be the state's last remaining coal-fired power station, Mount Piper, which is not due to close until 2042.
The mine area sits under the Newnes Plateau, adjoining the Greater Blue Mountains World Heritage Area, and parts have recently been gazetted as part of the Gardens of Stone State Conservation Area.
Opponents say the area must be protected by the federal government.
A world-renowned landscape
The federal environment department determined the project would have "likely significant impacts on world heritage, national heritage, listed threatened species and communities, migratory species and a water resource".
That means it would have to satisfy federal biodiversity laws, designed to ensure such impacts are avoided, mitigated or offset.
Both the federal Environment Minister and state government would need to sign off on the project.
In a submission to the federal environment department, Centennial Coal acknowledged the new mine area would have an impact on threatened species and a water resource.
However, upon review the environment department found it would also impact world and national heritage places, listed migratory species and ecological communities.
"Never have we seen such an extraordinarily large number of threatened species and communities within a single mine proposal area," the Lithgow Environment Group (LEG) said in a submission to the department.
The project would see Centennial Coal mine within 60 metres of the Coxs River, which feeds into Sydney's drinking water catchment.
Nearby are a range of swamps, including the Coxs River Swamp, Long Swamp, Kangaroo Creek Swamp and Lambs Creek Swamp.
The company's independent biodiversity report stated there were no federally listed Ecologically Endangered Communities (EEC) in the project zone.
That was contradicted by the LEG, which claimed all four swamps were EECs.
It accused the company of attempting to reclassify the swamps based on "extremely limited desktop searches" and flora surveys taken less than two years after "unprecedented" 2019 fires.
An independent biodiversity report stated mining there could contribute to "potential leakage" of groundwater dependent ecosystems but the company's preliminary assessments indicated it would not have a "significant impact".
Past damage
The Nature Conservation Council's policy director, Brad Smith, has welcomed additional scrutiny on the proposal, saying Centennial Coal "has form when it comes to underestimating the damage it causes".
In 2010, it was ordered to pay $1.5 million because of slumping at East Wolgan swamp on the Newnes Plateau.
"It's irreparable, it's impossible to bring those wetlands back," Mr Smith said.
The LEG said the mine would occur along a major geological fault line, meaning the possible impact on surface water and groundwater drawdown would be "significant and unpredictable".
Concern for threatened species
Julie Favell from the LEG warned tributaries of the Coxs River and the waterway itself, which are headwaters of Sydney's drinking water catchment, could be affected if the swamp systems dried out.
"They need to be protected at all costs for the future," she said.
The group stated there had been an "inadequate search effort" to identify the 10 federally listed and 17 state listed threatened species and communities.
Those species include the scarlet robin, greater glider, giant dragonfly and gang-gang cockatoo.
The company's independent biodiversity report identified two: the black gum and swamp everlasting.
The ABC sent detailed questions to Centennial Coal.
In a statement, a spokesperson said it was "preparing a comprehensive and robust Environmental Impact statement that addresses requirements from all government departments".
"Once the requirements become available, Centennial will undertake a thorough review and will address them accordingly," they said.
