This is the term chairwoman of the first panel session, Dee Murdoch, used to describe the contentious issue of final voids just before lunch.

An issue of great relevance considering Rio Tinto is proposing to leave a hole spanning 900 hectares and 300 metres deep, if their plan to expand their Mount Thorley Warkworth operation outside of Singleton gets approved.

And that mining in the Hunter Valley could leave a legacy of more than 10,000 hectares of land consumed as ‘final voids’”.

The associate director of AECOM stressing lateral thinking is needed when considering the question - what place could they play in the landscape of the Hunter Valley?

Some interesting ideas about how to turn these liabilities into an asset were floated; these included using the voids for aquaculture or as recreational lakes.

International success stories, like the Eden Project in the United Kingdom and the Island Copper mine in Canada, were referred to.

The Eden Project involved transforming a disused clay mine in Cornwell into an ecosystem biome project, educational centre, and concert venue.

However, it soon became evident future uses for the very deep holes left by large scale open cut mining in the Hunter Valley will be very site specific.

And that perhaps the “scaffolding needed to exit a site” should be in place at the start of a project and continually reviewed.

In addition, the planning process should encourage mining companies to look at all options, including the expensive process of filling or partially backfilling these spaces.

Although it should be remembered, “totally filling a void can wipe out the economic benefit of a project”.

Managing director of the Bloomfield group, John Richards explained most voids in the area go below the water table which limits how they can be utilised.

He cites salinity as an issue when it comes to aquaculture and said in general more research into the water quality of voids needs to be conducted.

“There is a long way to go in regard to potential uses of final voids as the discussions have to include mining companies, the landowners,  regulators and the community,” he says.

“Often what is commercially viable for a final void is not compatible with the desires of the community.”

Referring to the final void that will be left at his company’s Maitland site, Mr Richard suspects it will be used as a recreational facility.

“Although it is quite some time away the landowner is keen to create a lake with some surrounding land development.”

This was only one of the many topics covered at the annual conference that looks at best practice in restoration, regrowth, regeneration and reuse of mined land.

It began in 2011 as a partnership between the Newcastle University’s Tom Farrell Institute for the environment and the NSW Office of Environment and Heritage - only 60 delegates attended the inaugural event.

Its growth in popularity suggests it is not just the industry or regulators that need to consider a life for the Hunter Valley after mining.