Serious levels of highly toxic asbestos have been detected in material illegally dumped on a supposedly protected ancient Victorian grassland.

Tens of thousands of tonnes of fill have smothered the precious 40-hectare Truganina grassland and the species living on it in Melbourne’s west.

The illegal dumping occurred between December 2021 and January 2022, but the devastation was only discovered in April by a member of the conservationist group the Grassy Plains Network.

Now the contaminated material dumped on Conservation Area 9 has been found to contain serious levels of asbestos.

The Environmental Protection Agency has erected signs warning people against entering the site.

“First it was complete disregard for environmental values. Now it’s disregard for human health,” said Adrian Marshall, facilitator at the Grassy Plains Network.

“This illegal dumping was already an environmental tragedy but now it could have dangerous ramifications for the truckies who were directed to do it.”

WorkSafe Victoria is now investigating the incident over concerns for the workers involved.

Conservation Area 9 had been assessed as one of 36 biodiversity hotspots mandated for protection as part of the joint federal and state government 2010 initiative, the Melbourne Strategic Assessment.

The 36 Conservation Areas that are supposed to protect the last remnant vegetation in Melbourne’s vast growth corridors are almost entirely privately owned.

“This shows us how vulnerable a grassland in private hands can be,” Dr Marshall said.

“Not only can a privately held grassland be mismanaged with impunity, letting weeds smother the biodiversity, but they can be overgrazed as well, and there is damn well nothing that can be done.

“Some are heavily grazed. Developers are trying to build houses on them. Some are even being cropped. This is an unfolding environmental disaster.

“The Melbourne Strategic Assessment has been set-up to fail by both the federal and state authorities.”

Conservation and community groups have called on the federal government to:

• Ensure all other 35 conservation areas are legally protected and being properly managed
• Undertake an urgent independent ecological audit of the Melbourne Strategic Assessment to guarantee its proper implementation
• Assess the state of Conservation Area 9 and identify how it can be rehabilitated and restored
• Secure an alternative site of the same size and ecological value in metropolitan Melbourne.