At a meeting with the NSW Independent Planning Commission on February 5 the council raised serious concerns about the legacy of coal mining in a shire where coal has dominated for decades and re-shaped the landscape.

The council criticised Glencore for failing to release a closure plan for Glendell's expected closure in 2023, if its plan to more than double annual production at the mine near Singleton for the next two decades is not approved. Mine closure planning is supposed to occur from five years before closure.

"The underlying concern we have is that there is actually no detailed mine closure planning at the moment for this project... and we see that as a major gap," council development and environment manager Mary-Anne Crawford told the commission.

"It appears as though the applicant is wanting to defer closure planning to a future time and to be undertaken as part of an as-yet-unapproved project. So we consider that to be a little bit presumptuous.

"The crux of it is really about what are they going to do with this operation if they don't get approval, and they haven't contemplated that in either this modification application or their current approval requirements."

The commission is considering one of two Glencore proposals for the Glendell mine - an eight month expansion of the existing mine to recover 1.97 million tonnes - before assessment of a much bigger plan to expand annual production from 4.5 million tonnes to 10 million tonnes into a new area until 2044.

Submissions for the larger project close this week. The Glencore expansion plans have been strongly opposed by Hunter Strike for Climate students, who have called on Australians to support their campaign.

Singleton Council general manager Jason Linnane and planning manager Mark Ihlein told the commission the council and community were concerned about the shire post-mining, and the "lack of thoughtfulness and planning around the end of the process".

"How are we going to get some surety that from a social and environmental perspective we're going to be delivering outcomes through future post-mining activity on that land?" Mr Linnane said.

The council had serious concerns about long-term responsibility for final voids if they fail, and whether final land use options will be "safe, stable, non-polluting and sustainable", the commission was told.

Commission chair Stephen O'Connor said there were questions about how refusal of either of the Glendell proposals would impact on Glencore's other mine operations within the larger Mount Owen complex.

The council and community could be "left hanging for another 25 years" if "we're landed with this thing that's just going to sit there in a care and maintenance phase", Ms Crawford said.

The council was concerned about "what contingencies might be in place if the void fails", she told the commission.

"What are they actually going to do? And there is a risk that that could happen."

Ms Crawford was also sceptical about the basis of mine industry assurances about air quality, in an area with a concentration of large open cut coal mines, and particularly in the Camberwell area.

Mines routinely assured council and the community they had air management controls to address air quality, the commission was told.

"My question is, well, how successful are those existing air quality controls? What evidentiary basis is there to support that those management controls are successful, other than modelling?" Ms Crawford said.

"And if they are, great. Report that through to the community. But if they're not successful, what contingencies are being put in place to mitigate that and bring it back into the level of compliance that's required?"

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