A Main Roads contractor has used mulch containing asbestos while working on a major project in Perth's southern suburbs.

A document obtained by the ABC revealed Georgiou Group mulched approximately 10,000 square metres of the Russell Road bridge duplication site, near the new Aubin Grove train station, over the past three months.

Main Roads said tests showed the mulch contained small traces of non-friable asbestos, and therefore did not pose a public risk as fibres had not been released or become airborne.

The mulch has since been removed.

Resident Bert Russell, 77, said the mulch was placed five metres from his Twilight Mews property.

He became suspicious when he saw workers wearing face masks and gloves removing the mulch on Wednesday, and queried the matter with the Public Transport Authority (PTA).

"If I hadn't have put my head out the back door and seen this and been alert that something was wrong, then it'd have been swept under the carpet. No-one would have known anything about it," he said.

Mr Russell said a contractor visited him a short time after he called the PTA, and the worker confirmed the mulch had a "low risk" of asbestos.

He said he had not received any other communication from authorities.

"I don't know how bad it is. My grandkids can no longer go out there. Other kids in the street as well," he said.

Council demands answers

City of Cockburn Mayor Logan Howlett said he was shocked and disappointed when he was notified of the incident yesterday afternoon.

"We're calling for the State Government and its relevant departments - Main Roads, the Department of Environmental Regulation, the Health Department and others that may have an interest in this matter, to fully investigate what has happened here," he said.

"Now that all that mulch has been taken away under strict supervision, we've now got to say what mulch is coming back in? And how can they guarantee it has no levels of contamination?

"We'll be taking it up with the relevant government departments as a matter of urgency and the relevant ministers to get some explanations to our city but also importantly to our community.

"One would not expect those type of things to be happening in today's world."

Mulch cleared 'without delay'

Main Roads said the mulch had now been removed, with Georgiou working with independent consultants to develop a remediation action plan in line with government guidelines and requirements.

The mulch was removed after tests found traces of asbestos. ( Supplied: Bert Russell )

In a statement, Main Roads said a decision to remove the mulch was made without delay.

"There were no precautions or actions that the public could take beyond those being taken by the contractor which included immediate restriction of public access to impacted areas and the immediate saturation with water of impacted areas to prevent any potential release of fibres," the statement read.

Main Roads said six of the seven sites had been validated with a visual inspection and soil testing in accordance with the redemption plan, and expected the seventh site to be validated today.

The incident follows the discovery of asbestos in June in the roof of the new Perth Children's Hospital earlier this year.