Gardiner Reserve oval in Gisborne and Racecourse Reserve oval in Woodend were shut after it was discovered the contractor used turf sand supplied by a third party that was contaminated with broken glass, rocks and other unsuitable material.

As part of the council's routine grounds maintenance, the contractor was employed to undertake top-dressing of the ovals using 220 tonnes of soil on April 16 and 17.

Chief executive Peter Johnston said independent company Coffey Environmental Services had taken 36 and 40 test samples at Woodend and Gisborne respectively.

He said results received last Friday indicated the Woodend oval "has no signs of asbestos" and posed no risk to human health.

However, four small pieces of non-friable white asbestos, commonly found in household building materials such as cement sheeting, ceiling tiles and vinyl tiles, was found at Gardiner Reserve in Gisborne.

"Coffey Environmental Services indicate that 'the minor asbestos cement contamination identified is not considered to constitute a significant health risk'," Mr Johnston said.

"The council will be working with Coffey Environmental Services and other agencies as well as the contractor involved, in the steps required to successfully and safely clean up any remaining unsuitable material and return both ovals to a safe and usable condition."

The council has installed 'Ground closed until further notice' signs at both reserves and they will remain closed until deemed safe.

Mayor John Letchford said the safety of the community was paramount.

"We are investigating the contamination and the community should be assured we are being very proactive."

For further assistance and advice, residents can call the council's help line 1300557512. A council nurse can be contacted between 8.30am and 5pm until Friday on 54229265.