Upper Hunter Shire Council slammed the department's final responses to commission questions about the proposed re-opening of the Dartbrook mine, including advice the mine could go ahead even if it breached cumulative air quality standards for fine and coarse particle pollution.

The department advised the commission that "a consent authority is not prevented from granting consent if the non-discretionary development standards under the Mining State Environmental Planning Poicy cannot be complied with".

The advice came after the department conceded a Muswellbrook air quality monitor "commonly records exceedances" of the annual average PM2.5 fine particle standard, in response to commission questions about how Dartbrook conditions of consent would "manage cumulative impacts of air pollution".

Upper Hunter mayor and former Hunter Thoroughbred Breeders president Wayne Bedggood, in a final submission on behalf of the council, said a standard was "either discretionary or non-discretionary".

"A standard cannot be named one whilst having the effect of the other, unless that standard is more concerned with perpetrating a cruel hoax on those very persons it is nominally intended to protect," he said.

The department's advice was "doublespeak at its worst" and "Orwellian cynicism" which added insult to injury to people affected by cumulative air impacts from multiple large mines in the Muswellbrook and Singleton areas, Mr Bedggood said.

The council accused the department of failing to challenge Dartbrook owner Australian Pacific Coal's coal quality and price assumptions, or its future projections on coal exports.

The department's confidence that an average coal price of $95 per tonne over the next nine years "cannot realistically be attained or relied upon" and was contradicted by a Federal Government chief economist forecast in March of a decline in thermal coal prices to 2024 and slackening demand for coal in Asia, the council said.

The department had "ignored" questions about Dartbrook's coal quality assumptions which relied on processing facilities that were not part of its proposal.

The council also challenged the company and department on future markets for Dartbrook coal because of stated ash and sulphur content.

The company's target ash range of 15-24 per cent was higher than China's 15 per cent maximum ash content restrictions that were given as a reason for China to deny some Australian coal entry to Chinese ports early this year, the council said.

Dartbrook's coal sulphur content of more than 3 per cent was higher than the Newcastle sulphur benchmark content of less than 1 per cent, and a problem in South Korea which has recently banned coal with sulphur content higher than 4 per cent.

Australian Pacific Coal "has not demonstrated there is a market for its unwashed coal", the council told the commission.

"This is a proposal modelled solely on supply, while demand is not interrogated."

The council argued a $9.245 million rehabilitation bond did not reflect the size of the risk to NSW if the mine failed and taxpayers were required to meet closure costs, and advice from the Resources Regulator that it was unaware of spontaneous combustion issues in one of the Dartbrook seams "beggars belief".

The council included a section of a 2011 NSW Government report which stated Dartbrook's Wynn and Kayuga seams "have a medium to high propensity for spontaneous combustion".

Upper Hunter Shire Council remained "steadfastly opposed" to the recommencement of mining at Dartbrook, Mr Bedgood said.

The Dartbrook mine was placed into care and maintenance in 2006 after the deaths of three miners.

It was famously bought by Nathan Tinkler in December, 2015 as his proposed vehicle to return to the coal industry, but he withdrew from all Australian Pacific Coal positions after bankruptcy proceedings against him.

The company has an approval until 2022 to mine up to six million tonnes per year but is seeking an extension until 2027. It previously told the Department of Planning it would only mine 1.5 million tonnes per year.

In an earlier submission Muswellbrook Shire Council called on the NSW Government to fund a night-time air quality study of the Upper Hunter because of growing community and NSW Health concerns about the cumulative impacts of mining on air quality.

General manager Fiona Plesman said a 24-hour averaging period for monitoring air quality around the mines had the "unintended consequence of obscuring issues of elevated dust levels at night as a result of surface temperature inversions".

The Independent Planning Commission is expected to make a determination on the Dartbrook mine in coming weeks.