Chief Minister Katy Gallagher said yesterday the issue was likely to ''go legal'' after it emerged that the cost of the contamination-plagued North Weston Ponds project had blown out by another $15 million, to about $58 million, nearly three times its original price.

The Canberra Times revealed in late 2010 that up to 90,000 tonnes of soil contaminated with asbestos-laden building waste - dumped there over several decades - had been found at the site of the storm water project for the new Molonglo suburbs.

It was later found that 180,000 tonnes of the waste, and a collapsed sewer, were also present under the site, leading to a $23 million cost overrun, with most of the money devoted to the clean-up bill.

Tuesday's budget papers revealed that another $15 million was needed to finish the project after it had to undergo a complete design revision.

The Chief Minister said she had called in the ACT government solicitor after she had tried unsuccessfully to hold talks with her federal counterparts about the issue of dozens of former Commonwealth building sites around Canberra that now need decontamination.

Although Prime Minister Julia Gillard referred the dispute to Regional Affairs Minister Simon Crean, who agreed to set up a ''high level committee'', Ms Gallagher said her legal advice was that the Commonwealth continued to deny any liability.

''There are issues around who is responsible,'' the Chief Minister said.

''The Commonwealth's view is that when the land was transferred to the ACT we took on all risks and liabilities.

''The ACT's view is that polluter pays and this includes East Lake, where it's clear that the Commonwealth dumped massive amounts of asbestos-contaminated material there.''

In April last year, then chief minister Jon Stanhope wrote to the Commonwealth after the discovery of at least 600,000 cubic metres of contaminated soil - with a potential clean-up bill of $100 million - at the East Lake development precinct in the city's south.

Much of the waste is thought to have come from the building of Parliament House.

''There are ongoing discussions between Commonwealth and the ACT and we are continuing to obtain legal advice though our Solicitor General and consider our options,'' Ms Gallagher said. ''There are moral obligations on the responsible authority who allowed contaminated waste to be dumped in the middle of our city which need to be considered.''

Five ACT government agencies came in for harsh criticism from the ACT Auditor-General in May last year over their roles in the North Weston Ponds project.

The auditor found that the disastrous outcome of the job, where the full extent of the contamination turned out to be 180,000 tonnes, was due to risks that were known at the earliest stages of the project.