Hunter Valley Operations mine near Singleton says it has altered its 400 million-tonne extension proposal to reduce environmental impacts.
The mine, owned jointly by Yancoal and Glencore, proposes to extend the life of its HVO North open-cut from 2025 to 2050 and its HVO South operation from 2030 to 2045, extracting an extra 400 megatonnes of coal.
Environmentalists, farm lobby groups and The Australia Institute think tank have attacked the extension as a blow to Australia net-zero plans.
In a submission on the expansion project, the NSW Department of Planning and Environment's Net Zero Emissions Modelling team noted that it was difficult to cut emissions from open-cut mines but "the large increase in emissions from this project in the mid-2040s will require other parts of the NSW economy to decarbonise to remain on track with the NSW government's target of net zero emissions by 2050".
HVO general manager Dave Foster said on Thursday that the mine had amended its extension proposal after reviewing feedback on the project's environmental impact statement.
"We want to thank the government agencies and authorities, councils, organisations and community members who took the time to make a submission," he said.
"We've listened and refined the proposal based on that feedback."
Mr Foster said the changes included altering the route of the Lemington Road realignment and bringing forward construction of a low-permeability barrier to improve groundwater management.
He said the new proposal would affect 0.3 hectares of Warkworth Sands Woodland instead of 5.2 hectares, reduce impacts on Aboriginal heritage sites and cut direct greenhouse gas emissions and power station emissions by 16 per cent.
Lock the Gate Alliance NSW coordinator Nic Clyde said the company's changes were "cosmetic".
"Glencore and Yancoal's aggressive expansion of its HVO coalmine would still be responsible for pumping more than one billion tonnes of greenhouse pollution into the atmosphere once the coal is burnt," he said.
"This project will supercharge global warming and put people across NSW at severe risk of extreme weather and rising insurance premiums.
"The Minns government has a climate bill in Parliament right now, but if this immense mine goes ahead, it will outstrip any action that NSW takes domestically to rein in the climate crisis and instead put us all at risk."
