Residents of a Perth suburb fear for their health after being told asbestos-contaminated mulch was spread around as part of a train station project, but the transport minister says there was never any risk to the community.
Whistleblower Bert Russell said the material was laid in August and then scraped off on Wednesday and Thursday, but Aubin Grove locals weren't told why.
Mr Russell also said the workers, who were wearing face masks and gloves, told him to mind his own business when he asked what they were doing.
Persistent badgering paid off and he was finally told about the contamination.
"I was annoyed - my grandkids have been playing outside the back of my house and this dust has been flying around for months. We didn't know anything about it," he told reporters on Friday.
But Main Roads said only small traces of non-friable asbestos-containing material was discovered last week among 10,000 square metres of mulch laid as part of bridge duplication work on Russell Road to provide greater traffic capacity for the new train station.
The pieces were bonded and not airborne, so the health risk was negligible, Main Roads said.
Lead contractor Georgiou Group fenced off the areas and hosed down the ground to prevent any potential release of fibres, but results of air monitoring were below Department of Health guidelines, Main Roads said.
Transport Minister Bill Marmion said the final stages of the clean-up were expected to be complete on Friday.
Georgiou Group would shoulder some of the $20,000 cost, but there would be no cost to the taxpayer, a Main Roads spokesman said.
Opposition health spokesman Roger Cook said it appeared building rubble had been mixed in with the mulch and local residents should have been informed sooner.
"It must be extremely worrying for these people," Mr Cook said.
"It's extraordinary that it took the actual residents harassing the government for them to get the answers that they obviously deserved.
"The government should have acted sooner."
Mr Marmion accused the opposition of using residents as pawns for a cheap political shot.
"At no point were any members of the public at risk and for the opposition to suggest a lack of concern for residents is simply scaremongering," he said.