The ACT government is suing two companies for more than $10 million for alleged failures to detect the extent of asbestos contamination at the troubled North Weston Ponds project.
Soil at the North Weston Ponds site was found to be highly contaminated with asbestos in late 2010.
Up to 90,000 tonnes of soil was contaminated by asbestos-laden building waste, causing a huge headache for the ACT Government.
The costs of the stormwater project blew out significantly, doubling in price to $43 million.
The waste was left before self-government, and the ACT government stated in 2012 it was preparing to sue the Commonwealth.
But it has now emerged that the ACT launched civil action against two private companies; SMEC Australia Pty Ltd & CM Jewell & Associates.
It is claiming in excess of $5 milllion from each company for alleged breach of contract and negligence.
SMEC Australia was contracted to prepare an environmental and site assessment, and a remedial action plan for the site.
Jewell was allegedly responsible for audits and oversight of the methodology SMEC had adopted.
It is alleged the defendants' actions led to an inadequate sampling and analysis of the soil before the pond was designed.
As a result, it is alleged the amount of contaminated landfill that needed to be removed was "significantly underestimated".
The ACT claims it incurred extra costs once it realised the true extent of the contamination, because it had to redesign the pond, and shoulder additional remediation, construction, and other costs.
The respondents were first made aware of the claim in September last year, although they were not formally served until March this year.
But the ACT applied to the ACT Supreme Court to force the respondents to file their defence to the court by June.
The case is highly complex, with years of history, and tens of thousands of documents already involved.
The respondents asked for more time to file their defences, seeking to defer it until September or October this year.
But the ACT feared that may tie their hands, should the two companies claim a defence of "proportionate liability" - a defence that other wrongdoers had also contributed to the negligence.
If that defence was used, the ACT feared delaying it until September or October would prevent them from making claims against the other alleged wrongdoers.
Associate Judge David Mossop on Tuesday found in favour of the ACT.
That means the two companies will need to file their defence to the allegations by June 22.