The epic Independent Planning Commission (IPC) inquiry wrapped up on Saturday after seven days and over 400 speakers on the controversial plan to build 850 coal-seam-gas wells in and around the Pilliga forest near Narrabri.

DPIE Executive Director David Kitto earlier conceded the proposed $3.6 billion project would not reduce gas prices. He was called back before the IPC on Saturday alongside Department colleagues Mike Young and Steve O'Donoghue.

READ MORE:

He rejected concerns that planned or emergency flaring could start a bushfire, landholders' worries about loss of groundwater which he said would take 1000 years, and said the Department doesn't agree with water academic Stuart Khan that the company should be obliged to convert salt waste by-product into baking soda.

But Mr Kitto also threw into doubt a longstanding Santos claim the project was needed to meet a perceived imminent shortage of gas.

"There's more than enough gas being produced in Australia for domestic use," he said.

The DPIE chief said a lot of Australia's gas product is "subject to long-term commercial agreements" that the product be exported. Companies would be subject to significant penalties if they sold it domestically, but government could force them to do so anyway, he said.

"The Commonwealth government has the levers to require that to be done. They've got special powers that they can invoke to make sure there's enough gas for the domestic market," he said.

"But it is a last-resort power."

He said the Queensland government considered export a way of "maximising the return on the state's resources".

Exporting gas may also have "benefits in terms of using gas in Asian countries and throughout the world in terms of helping to transition to a low-emissions economy."

Want more local news? Subscribe to the Leader to read it here first

Opponents of gas production have long insisted a gas reservation policy - requiring exporters meet Australian demand for the fossil fuel before exporting it - would resolve a perceived long-term shortfall in the product. Australia is the world's biggest gas exporter.

They have also pointed to a proposed gas import terminal approved to be built at Port Kembla as making new domestic CSG projects financially unviable.

But Mr Kitto also cast doubt that the Port Kembla facility or another proposed to be built in Newcastle would ever be constructed, despite being declared of critical state significance by the NSW government.

He said ultimately governments want to increase domestic production of gas so long as new CSG projects are safe and environmentally sustainable.

"I guess from a risk perspective, the state's saying you wouldn't want to put all your eggs in one basket," he said.

The controversial project broke records for public submissions, with an unprecedented 404 people registering to have their say on the scheme.

Several speakers including President of the Narrabri and District Chamber of Commerce Russell Stewart, who said local business is strongly in favor of the scheme, spoke in favor of the mining project.

But opponents were in the majority, with speaker after speaker taking 5 minute slots to condemn it as a threat to water, health and the planet's climate, among other issues.

The former chief scientist of NSW, former head of Fire and Rescue NSW, academics, scientists and economists all spoke against the project.

The IPC must announce whether it will approve or refuse construction of the Santos Narrabri Gas Project by early September.

Support the local news that keeps you informed - subscribe today.