The 40 hectares of Crown land off Metford Road selected for the hospital formerly housed a quarry and brickworks and are part of a 50-hectare parcel that is still under lease to CSR.

While clay mining and brick manufacture ceased on-site more than five years ago, the land must be rehabilitated before the company can be released from the terms of several mining leases blanketing the site.

CSR property manager Andrew Mackenzie said the company was following statutory requirements to the letter and had a government-approved mine closure plan.

“What that entails is reworking the landform, 

re-vegetating it, care and maintenance and, upon completion of all those things, eventual handover and surrender of the site, which will take many years,” he said on Monday.

The Baird government promised before the March election it would start work on the much-needed hospital within four years, and committed $25 million to fast track the project.

“Work will be under way on the hospital by next term – this is a green light,” Premier Mike Baird announced during the final days of the campaign.

Mr Mackenzie said work had started on an area of the property not sought for the hospital.

He said this would be done by Christmas, but “we haven’t ­started on the main section of the site and do not intend to start that until we’ve completed that other side”.

It was then a case of wait and see whether the land was sufficiently remediated, in terms of revegetation requirements, he said. He declined to comment on the government’s election commitment.

Health Minister Jillian Skinner said on Monday that “remediation issues were care­fully considered during the master planning phase for the Lower Hunter hospital”.

“Remediation works are under way and will not delay the project commencing this term, as ­promised,” she said.

The NSW Division of Resources and Energy said the mine plan had been approved until 2019 and set out that the majority of the rehabilitation would be finished by 2018.

The next state election is due in early 2019.

Internal documents tabled to State Parliament late last year suggested the government expected remediation of the land would be finished sooner.

Labor has questioned whether Metford was chosen from more than 30 potential Hunter Valley sites as a cheap option because it is Crown land.

Cessnock MP Clayton Barr said he knew of three landholders who had nominated properties in his electorate when the government called for expressions of interest.

“They were never even contacted,” he said.

He said the government had not given a project timeline, funding model, details of hospital services nor justified its politicised choice of site. 

“We should all be excited about this new hospital but they’re making it hard,” Mr Barr said.

The government says it is completing a final business case that will spell out the details.