The long-running legal battle over the 2009 Walla tip fire is far from over with the case going to the High Court of Australia.
The NSW Court of Appeal delivered a finding in April in favour of residents affected by the fire, but the council's lawyers are now seeking an appeal.
Maddens Lawyers Class Action Principal Brendan Pendergast said his team were preparing a response to their special leave application.
"That has to be filed with the court within the next two weeks," he said.
"Then the High Court will consider the respective parties' arguments and make a decision as to whether the leave will be granted to the defendant, to appeal before the High Court."
Mr Pendergast said the High Court could review the application based on documents alone, or request a hearing to decide if the appeal should go ahead.
"Our client group are disappointed there's been no desire by the defendant to attempt to reach a resolution at any stage," he said.
"Their disappointment is revived by the fact they're now seeking leave to appeal the Court of Appeal decision.
"But that's due process according to our legal system, and we just have to deal with it.
"Certainly I've not been involved in a class action that has resulted in an application to the High Court."
In other news:
Despite the development, Maddens Lawyers is moving ahead with the class action and will hold a meeting at the Gerogery Hall on June 17.
"We'd urge people who were impacted by the fire and have never done anything about it to register; that's the only way they'll be able to recover compensation," he said.
"We will arrange for loss assessments to be done on their properties.
"One very important aspect of this fire is because the fire occurred so long ago, there's a significant interest component that applies.
"We anticipate based upon the preliminary work we did for the purposes of mediation and the calculation of interest and legal costs, the claim will be well in excess of $20 million."
Mr Pendergast hoped an agreement could be reached outside of court for how claims to damages would be determined for the class action.
"We're going back to the supervising judge of the class action on July 12 in the Supreme Court in Sydney," he said.
"We're hopeful we'll have some indication as to what's happening with the High Court application by then."
Greater Hume Council originally won in the Supreme Court in 2018, but three judges in the appeal case unanimously agreed that the council's management of the tip breached a duty of care.
The lead plaintiff Sharon Weber was awarded damages of $104,400 plus interest, and the court ordered the council to pay her legal costs.
If an appeal is heard in the High Court, it will be the end of the line for the case; there are no further appeals once a matter has been decided by the High Court.