The plan covers 19,000 hectares and, if approved, will see 10.5 million tonnes of coal extracted each year, an increase from the current 7.5 million.

The $367 million expansion will secure more than 1100 jobs, the company says.

Rivers SOS member Caroline Graham said hundreds of houses in Wilton, Menangle and Maldon would be cracked and damaged if the proposed mining went ahead.

``We saw a hundred houses damaged in Appin after mines went under the town and some had to be demolished,'' Ms Graham said.

The mining company's general manager sustainable development and external affairs, John Brannon, said there was a well-established process for managing potential negative affects on properties in a mining area.

``This includes one-on-one consultation with property owners, representatives of Illawarra Coal and the Mine Subsidence Board,'' he said.

Ms Graham said mining would also come within 100 metres of the Nepean and Cataract rivers.

``Rivers SOS calls for a safety zone of one kilometre in order to protect rivers from cracking, pollution, diversion of flow and desiccation as we have witnessed in the past,'' she said.

``But the company is not even meeting our call halfway.''

Mr Brannon said there was no ``one size fits all'' approach to mining near rivers.

``Illawarra Coal's plan in relation to rivers and streams is based on many years of data, research and analysis,'' he said.

``We are now able to predict with a high degree of accuracy what surface impacts our underground mining operations will have.

``We currently position our longwalls at varying distances from the rivers because we know from research that it is the topography of the surrounding land which is the main determinant of our impacts on rivers and streams.

``By positioning longwalls away from rivers and streams the company sacrifices some 70 million tonnes of coal, approximately 7-10 years of production from the Appin and West Cliff mines.''