Peabody seeks to extend Metropolitan coalmine until 2044 amid water catchment concerns

Peabody's plan to extend its Metropolitan coalmine at Helensburgh, south of Sydney, until 2044 has drawn warnings about the drinking water catchment while winning strong union support.

The US-based company has submitted a scoping report to the NSW government, formally beginning the State Significant Development process for 22 additional underground longwall tunnels west of the mine's existing operations.

The project would extract about 31 million tonnes of run-of-mine coal over 12 years, at a rate of up to 2.7 million tonnes annually.

Peabody said it would preserve about 400 existing jobs, support 450 suppliers and continue providing coal to BlueScope's Port Kembla steelworks and overseas customers.

More than 40 per cent of Metropolitan's current product supplies Australian steelmaking, according to the company.

Union backs expansion

Mining and Energy Union district secretary Andy Davey said the union supported the extension "100 per cent".

"This would be huge, not only for the workers, but the community," he said.

Mr Davey said the project would provide significant employment certainty for Metropolitan's approximately 400 workers.

He acknowledged the proposed expansion was within the catchment but disputed claims it would drain water into the mine.

"What people have to understand is that there's a massive sandstone conglomerate in the roof support," he said.

Peabody explains new design

Peabody said the proposed expansion would be west of existing operations and away from Woronora Reservoir.

Its scoping report confirms the project would remain within the Woronora Special Area, which forms part of Sydney's drinking water catchment.

The company proposes using 163-metre-wide extraction panels separated by 55-metre pillars to reduce subsidence effects.

A Peabody spokesperson said Metropolitan had consistently complied with consent conditions requiring "negligible impacts" to upland swamps and water quality and quantity since its current project approval was granted in 2009.

The spokesperson cited a 2018 NSW expert panel finding "no evidence" of fractures connecting the underground workings to the surface.

"Metropolitan will keep operating its proven, conservative mining design in order to comply with its consent conditions," the spokesperson said.

Peabody said the proposed continuation area would add about 1,300 hectares, compared with 6,200 hectares covered by its existing mining leases.

The company also proposes a methane-abatement plant, which it said would begin operating in 2032.

Separately, Peabody is also seeking approval to extend Longwall 317 and add Longwall 318 which remains under assessment and has received critical advice from the federal Independent Expert Scientific Committee (IESC).

It found Peabody's modelling did not provide an adequate or defensible basis for predicting impacts on protected upland swamps, groundwater-dependent ecosystems and waterways flowing into Woronora Reservoir.

"The IESC cannot envisage any feasible mitigation measures, including offsets, that could safeguard these irreplaceable water resources and water-dependent [matters of national environmental significance]," it said.

Greens raise catchment concerns

NSW Greens Environment spokesperson Sue Higginson said mining had already damaged parts of the Woronora catchment.

"It's a legacy mine situated where no mine should be," she said.

Wollongong Greens councillor Deidre Stuart described the scale of the new project as "massive".

Last year, she unsuccessfully moved for Wollongong City Council to oppose the Longwalls 317 and 318 modification and request an Independent Planning Commission determination.

Cr Stuart said the smaller proposal had indicated Peabody intended to pursue a larger western expansion.

"I just feel a bit sickened and disgusted, to be honest," she said.

"I want to see our water catchment protected because that supplies the water and it holds the water."

Proposal at an early stage

Planning Minister Paul Scully said the department was awaiting further information from Peabody about the smaller proposal's potential impacts on waterways and nearby swamps.

It has also requested technical advice from the NSW Independent Expert Advisory Panel for Mining.

The separate 22-longwall project remains at the earliest planning stage, with no full development application lodged.

If an application is lodged, it will undergo an environmental assessment and a public exhibition.

It will be referred to the Independent Planning Commission if it receives more than 100 eligible objections.