The company submitted an environmental assessment for its Bulli Seam Project to the Planning Minister last October.

It outlines requirements for the future operation of a potential 129 longwalls at the Appin and West Cliff mines.

Illawarra Coal's general manager of sustainable development and external affairs, John Brannon, said the assessment included mapping 130kilometres of creeks and streams in the proposed 188-square-kilometre mining area.

``The purpose of the Bulli Seam Project application is to enable the ongoing operation of our mines, to ensure the jobs of more than 3000 people in our region,'' Mr Brannon said.

Rivers SOS member Julie Sheppard said the plan proposed undermining 47 significant tributaries of the Georges, Nepean, Cataract and Woronora rivers.

``It also proposes the undermining of many of the upland swamps which feed these river systems,'' she said.

``Even if they are not proposing to directly undermine the major rivers, they will be undermining many of their tributaries and the feeder swamps which comprise their headwaters.

``This is likely to severely affect downstream water quality and quantity, as a river is the sum of its tributaries and headwaters.''

Mr Brannon said Illawarra Coal had operated in the Wollondilly region for nearly 50 years, and had mined beneath many creeks and streams, none of which had disappeared due to mining.

``There is no evidence to support claims that mining impacts from the Bulli Seam Project to streams, tributaries or swamps will result in the drying of rivers or loss of water to the catchment,'' Mr Brannon said.

The hearings will be held at Appin House next Wednesday and Thursday from 9am, run by the Planning Assessment Commission under the Department of Planning.

The commission will send a report to Planning Minister Tony Kelly who will decide whether to approve the mine plan.

Environmental groups,, including Rivers SOS, will present their case at the public hearings, as will local councils and Illawarra Coal.

Those interested can lodge a written submission or apply to give an oral presentation. Call Rohan Tayler on 93832104 or email rohan.tayler@planning .nsw.gov.au by February 12.