The builder of the City Link tollway has been ordered to clean up its act, after the Environment Protection Authority found it had dumped 24,000 cubic metres of potentially toxic silt on private land near Mordialloc.
A senior executive with the Transfield Obayashi Joint Venture said yesterday he did not know how much potentially toxic soil had been removed from the City Link construction site so far.
He also could not say where the soil had been shifted to since the company stopped using land in Braeside, along the Mordialloc Creek, in March for for ``commercial'' reasons.
The State Government yesterday enacted new regulations to deal with the dumping of acid sulfate soils, after the EPA admitted it had been powerless to properly manage it.
A phone caller tipped off the EPA last November about the potentially toxic dumping of soil near Port Phillip Bay at Braeside, but it took until 30 July for a notice to be served on the joint venture partners to clean up the site.
The EPA found the soil had caused or was likely to cause pollution by generating acid run-off into the creek.
Mr Mat Jacobson, whose family owns the Braeside land, told The Age that Transfield-Obayashi had known for more than a year that the soil was potentially acid-generating ``but we were simply informed that the material was clean fill''.
In a letter to Mr Jacobson on 20 May, the joint venture's environment manager, Ms Jane Waldock, said she did not consider ``the quantity or nature of material taken to that site to date will cause an off site impact''. She said the decision to stop depositing further clean-fill was based on ``commercial considerations''.
The head of the EPA, Dr Brian Robinson, said the acid-generating properties of Coode Island silt had been well known for decades, but there were no guidelines until yesterday to deal with it because it was not hazardous unless removed.
The naturally occurring sulfides in the waterlogged sedmiments around the bay - which have been exposed by the construction of City Link tunnels and the Docklands redevelopment - become toxic when exposed to air.
``(This) could have been foreseen, perhaps it should have been foreseen, but at this stage no damage has been done and the proper measures have been taken,'' Dr Robinson said.
The EPA has ordered Transfield-Obayashi to conduct its own tests and produce a management plan by 1 September.
Dr Robinson said the EPA's tests had shown no environmental damage ``at this stage'', but oxidisation could produce high amounts of sulphuric acid which could kill marine and organic life if it was not managed.
``If it is not properly managed it could pose significant problems to acquatic environments,'' Dr Robinson said.
Transfield-Obayashi's project manager, Mr Rob Cranston, yesterday said all soil removed from construction sites had been inspected by the EPA to ensure it met regulations.
He said the decision to stop using the Braeside site was made in conjunction with advice from the EPA, but it was ``debatable' whether the material was contaminated.
Mr Cranston said a comprehensive management plan would be devised in conjunction with the EPA, but Transfield-Obayashi's own tests had found the material was ``acceptable'' under the old guidelines.
Dr Robinson said the new regulations would give clearer guidance to construction companies on their obligations when extracting acid sulphate soil.
The new policy requires soil to be taken to a properly licensed site or one with an approved EPA management plan.
The Opposition transport spokesman, Mr Peter Batchelor, said the Government's failure to properly manage the City Link project could cause an ``environmental catastrophe'' for Port Phillip Bay.
