For seven days commissioners heard submissions from speakers who represented some of the 23,000 submissions against the project.

On Saturday afternoon a little after 3pm Department of Planning, Industry and Environment director David Kitto was called back to the commission to explain some salient points.

He was virtually flanked by DPIE executive director Mike Young and senior planner Stephen O'Donoghue.

The first question was whether climate change had been factored into the department's decision to allow the project's development.

Mr Kitto said it had, particularly in the case of bushfires.

He said a bushfire was expected in the Pilliga State Forest at least once a decade or more often, because it had substantial fuel loads.

He said climate change would be expected to cause an increase in frequency of bushfires and their intensity.

"We would expect increased periods of catastrophic fire danger," he said, and that would likely mean project proponent Santos would have to defend its infrastructure from fire more often.

Mr Kitto said the department's assessment had been based on worst-case scenarios modelled by the Rural Fire Service.

He downplayed the likelihood of safety flares, of which there would be two - one in the Pilliga forest and another outside, being operational on days of catastrophic fire risk.

"The flares would only operate in periods of non-routine operations, for instance maintenance, or in an emergency.

"You can't schedule emergencies, but you can schedule mainenance," Mr Kitto said.

Yet a 135-metre radius clearing around the 50m-high tower would minimise the chances of fire starting because of the flare, he said.

"Similar flares have been used in bushfire-prone areas."

The original proposal also included six unshielded 'appraisal flares', generally used to flare gas until the source was contained within the company's holding infrastructure.

The department had deemed no appraisal flares should be necessary, said Mr Kitto.

And if Santos did lose its infrastructure in a fire, that would be a problem for Santos.

Mike Young said Santos would also be expected to ensure its own firefighting equipment would be available to help the RFS fight bushfires in the vicinity.

Commissioner Professor Snow Barlow persisted with the questioning: "We've heard from fire experts during the hearing that a naked flame is vulnerable to detrius being driven by high winds through the flame and willie willies lifting up bark etc in the surrounding area to create a potential ignition source.

"Has that been evaluated?" asked Prof Barlow.

Mr Kitto said there would be firefighting capabilities on site and workers around all the time, meaning reaction to any fire starting would be rapid.

And he said while it was theoretically possible a safety flare could start a fire, there would be many factors that would have to come together for that to occur, and even then a fire could be controlled.

Mr Young said the department would expect Santos to be monitoring weather conditions and the use of the safety flare would be rare, however a pilot flare would operate all the time.

Professor Barlow asked if it would be possible to shield the flares, noting the World Bank's desire to have zero flaring of gas by 2030.

Mr Kitto acknowledged the World Bank initiative and said the safety flares did not fall onto the bank's definition, because the gas would not be flared as waste and appraisal flares would not be part of the project.

Mr O'Donoghue said it was feasible to flare horizontally in a walled-in area, but because of the rare use of the flares - Santos estimated twice a year - shielding would be difficult.

The commissioners then moved onto issues related to groundwater.

The department heard there were great concerns about farmers having to prove evidence of a loss of water and the great costs of building such a case and how this could be overcome?

Mr Kitto said the argument mainly concerned the draw-down of nearby bores and current modelling had predictions of shallow acquifer drawdown at about 0.5m, negligible and below standards.

For any action to be needed the actual drawn-down would have to be much greater and even then any impact would be "avoidable and reversible," he said.

Mr Young said in the unlikely event of an issue, Santos would be expected to have short-term mechanisms to supply water for a landholder's "immediate needs", being stock and domestic supplies.

Mr Kitto said more work needed to be done to determine whether any regional faults existed that connected shallower and deep acquifers, but at this stage they were unaware of any that did so.

Nearby bores will be monitored, said Mr Young, but Santos would not necessarily decide which bores, because it would "not be a case of Santos monitoring itself".

There are 37.5 gigalitres of water expected to be needed during the life of the project and Mr Kitto said Santos would need to own water entitlements up front as a condition of the project.

On the matter of biodiversity offsets for the project, the department was asked whether it thought land required to meet conditional offsets would be available on the open market?

Mr Kitto said the entire project had been based on 1000 hectares of clearing.

"That should never happen, we're looking probably at 70 per cent of that, and Santos would have to then own 70pc upfront," he said.

He said having considered commercial land prices the department considered it "can be done".

He said it was not necessarily entire properties in question, several farms had biodiversity-valued land and the offsets could be spread across many properties, giving farmers the ability to profit from locking areas up.

Mr Young said it did not have to be a case of Santos buying up land and becoming the area's major landholder.

Prof Barlow asked about fragmentation of wildlife habitat and what fencing would be required?

Mr O'Donoghue said the priority was to minimise clearing and that infrastructure corridors would not need to be fenced.

Mr Kitto said there were legislative levers that could mandate fencing if neccessary, but Prof Barlow said he would propose no fencing to avoid habitat fragmentation anyway.

On the question of fugitive emissions the department was asked about Santos's estimate of CO2 content being about 5pc and whether that was truly representative of the project, given the hearing had heard that content could be as great as 20-30pc?

Mr Kitto said venting of CO2 was the key emission to be considered, both economically and environmentally.

"Santos doesn't want CO2, they want methane," said Mr Kitto, and the levels varied across the site.

He said on the project's eastern boundary higher levels of CO2 would be expected and Santos would likely avoid those areas because CO2 "doesn't pay".

Mr O'Donoghue said in volcanic areas CO2 content would be greater and those areas might not be viable to exploit.

Prof Snow asked if the Environmental Impact Statement had used an assumption of an average of 10pc CO2 content and whether that was reasonable?

Mr Kitto said the department thought it reasonable and sensitivity measuring could be demanded.

Senior Counsel assisting the commissioners Richard Beasley said some submissions to the hearing had suggested Australia's domestic gas price was now tied to international prices and the Narrabri project would have no affect on domestic prices.

"They suggested NSW doesn't need the Narrabri Gas Project, that it's not critical to NSW."

Mr Kitto said NSW currently used 125 petajoules of gas a year and the transition to renewables would be a challenge, but NSW may use less, depending on whether heavy industry decided to stay in Australia.

He said the east coast was facing the most rapid transition to renewables, but still faced significant challenges.

Mr Beasley said he didn't think the submissions to the hearing were prefaced on transition to renewables tomorrow, more the fact the Narrabri project wasn't needed, that gas could come from Port Kembla's import terminal and there was more than enough gas for the domestic market.

Mr Kitto said there was a need to increase domestic gas supplies and it was critical NSW had a secure supply.

He said the pipeline network needed to be increased as did supply.

The Australian Energy Market Operator has suggested the east coast is facing a potential shortfall by 2024, he said.

"From a planning perspective the Narrabri Gas Project is consistent with government policy, to ensure consistency we need more gas," said Mr Kitto.

Asked about disposing of salt waste from the project Mr Kitto said there was a spectrum of ways to do it.

He said re-using the salt waste as a by product would be best and disposal as landfill would be a "last resort".

He said the waste could not compared with that coming from wells in Queensland because its composition was different.

"It can't all be sorted out beforehand, every means of disposal comes with costs and Santos will have to bear those costs."

He said the department wanted work on waste disposal done quickly.

At a socio-economic level, the department representatives were asked about projected job losses from other sectors of the economy because locals might gravitate to the gas project.

Mr Kitto said he thought extra jobs were more likely to create opportunities within the local community.

Mr Young said construction and operational jobs were very different and required different skill levels.

"I think fears of an exodus from existing jobs unlikely," he said.

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