It has approval to drill eight wells but is seeking permission from the NSW Government to expand this to 26, drilling up to 550m into the coal seam and targeting the mine’s goaf (areas already mined for coal) as well as parts of the seam that have not yet been mined.

The gas drainage project would make the mines safer and more efficient, but they have caused some figures close to the industry to question whether it could be a coal seam gas operation by stealth.

While the Apex-Ormil coal seam gas project at Darkes Forest drew 1300 submissions against its approval, Illawarra Coal’s plans drew just five submissions.

Illawarra Coal, a subsidiary of BHP Billiton, recently won approval to expand its Appin and West Cliff mines over the next 30 years.

Illawarra Coal external affairs manager John Brannon said the company had been extracting gas from the heavily gassy coal seam for more than 20 years. He said the plans did not involve the controversial ‘‘fracking’’ process.

‘‘The company has been draining gas from Appin and West Cliff operations to ensure a safe working environment since the late 1980s and most of the gas is used to generate electricity,’’ he said.

‘‘The coal in the Bulli seam [which is mined at Appin and West Cliff] has high levels of methane gas.

‘‘To minimise the risks associated with gas build-up in the mine, the gas is removed from the seam before and after mining by drilling from underground and also from the surface.’’

Two bores would be tunnelled under the Hume Hwy and the railway line to pipe gas to an extraction plant.

In the five submissions, all from government agencies, the strongest was from Wollondilly Shire Council, which said it was concerned about the impact of extra heavy vehicles on the roads. The Mine Subsidence Board had no opposition to the plan.

Illawarra Coal is reviewing the submissions.