Bargo residents facing a new threat after devastating bushfires

Residents in a fire-ravaged community south-west of Sydney are again facing the threat of losing their homes, this time to damage caused by a proposed mine expansion.

Energy company SIMEC is looking to expand its Tahmoor longwall coal mine under Bargo, with families told their properties could sink by up to 1.6 metres.

The damage is predicted to be so severe it's estimated 140 homes will be impacted, with 20 homes will have to be acquired by the mine, because they will be unlivable.

Jenny and Geoff Web's block is in the danger zone.

They've only just had their plans to rebuild approved by Wollondilly Council, 14 months after their home burnt to the ground in the Green Wattle Creek fire.

"Half the house could just fall into that hole. The other half could stay exactly where it is. We don't know," Mr Web told 9News.

"We can't sell obviously because of the fires, and now because of the mines," Mrs Web said.

The issue is dividing the local community, with the CFMEU campaigning for the expansion, saying it will save about 400 jobs.

"Claims about subsidence were addressed during the Independent Planning Commission's (IPC) hearings last month and Tahmoor Coal reaffirmed its ongoing adherence to the statutory procedures governed by Subsidence Advisory NSW," Tahmoor Coal Mine said in a statement.

"Throughout the planning process, we have listened and taken into account concerns raised by the community and government, resulting in significant amendments including the removal of two longwalls directly beneath the township of Bargo.

"We await the IPC's decision."

Liberal MP Nathaniel Smith, the local member for Wollondilly, is also speaking out against the mine, fearing for the mental health of his constituents.

Subsidence can take up to a decade to show, leaving a cloud hanging over the area, long after the mining starts.