The material was discovered as contractors were excavating a raised mound at the southern end of the ground, council acting parks and recreating group manager Tom Dyer said.
Last night, temporary fences were put around two mounds which were covered in plastic sheeting weighted with tyres.
Analysis was being undertaken last night to confirm exactly what the material was.
"We are taking all practical steps to keep contractors, staff and the public safe," Mr Dyer said.
The council and Downer responded quickly to the discovery of suspect material in the mound, My Dyer said, to keep the community safe.
"Work stopped immediately and an appropriately qualified specialist was brought in to assess the material," he said.
"It was confirmed it was likely the material was asbestos and appropriate precautions were taken straight away."
WorkSafe New Zealand was notified and the council and contractors fenced off the area.
Signs were erected advising the public of the asbestos risk within the enclosed area and most of the material was covered with clean fill to avoid any potential for exposure, Mr Dyer said.
"Some small pieces of material have been left in piles of fill — these areas have also been fenced off," he said.
The material would be removed and council staff would contact organisations which use the area to advise them of the situation.
"There is likely to be a delay to the overall project, but the DCC is committed to ensuring the site is safe and that the project will be completed," he said.
The $300,000 project would significantly improve the practice and playing surfaces, creating two flat, irrigated fields suitable for hosting professional and community sports all year round.
Before the discovery of the material, the project was estimated to finish in late February.
