The Chief Minister has sought assurance from Actew that cracking in the Cotter Dam extension does not pose a safety or financial hazard to the water security project.
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The Canberra Liberals say there is a potentially serious structural problems at the $415 million dam, and have written to the territory's top building bureaucrat and work safety authorities asking for an investigation.
Liberals' frontbencher Vicki Dunne says that documents made public under Freedom of Information laws in June show that a dam crack that emerged in April is ''potentially serious'' and is demanding a probe by the territory's dam regulator.
Actew managing director Mark Sullivan, who made the existence of the crack public in April, has written to the Chief Minister, saying the dam's construction was meeting or exceeding safety standards and that Mrs Dunne's actions were politically motivated. Mr Sullivan's report to Chief Minister Katy Gallagher said the dam regulator had already signed off on the corrective measures taken about the crack, which ''posed no serious issue with the quality, safety or functionality of the Enlarged Cotter Dam''.
But Mrs Dunne says she has been advised by ''experts in the field'' that the crack could have ''potentially serious consequences''.
''Experts in the field have told me that this crack has potentially serious consequences, especially if it extends into the higher parts of the wall,'' Mrs Dunne said.
''The Bulk Water Alliance report uses very technical language to say that the section of the dam wall affected by the crack could be ''compromised'' if the crack is not contained.
''An internal government email, also on the FOI website, and which reveals that there is a second crack in the wall, says that Brian Forbes, a world-leading expert on dams of the kind being built at Cotter, has expressed 'disappointment at the poor quality'. Mr Forbes, a member of the technical review panel for the project, said yesterday that he was unable to comment but Mr Sullivan dismissed Mrs Dunn's attack as ''a nonsense''.
The managing director said cracks had appeared after flood waters flowed over the top of the dam in late February and early March this year.
''I talked about the cracks on ABC radio in April,'' Mr Sullivan said.
''The concern was that cold water flowing over the dam had produced some surface cracks.
''The worry of the technical review panel was that those cracks did not turn into something more sinister than that. They proposed a mitigation strategy as to how to cover and seal the cracks which basically involved some big sheets of metal. They've done that to everyone's satisfaction and since then we've had some thermal modelling done by GHD, the dam designers.
''The conclusion is that the cracks have been mitigated and pose no threat to the dam.''
Mr Sullivan said he was asked for an assurance by the Chief Minister after she became aware that the Canberra Liberals were saying the dam had a serious problem.
''The offer has been open to any political party if they have concerns about the dam then they should talk to us and we have been very open in dealing with them,'' Mr Sullivan said.
''The fact that they [the Liberals] haven't raised it to me, suggests there's probably nothing to it.
''I had decided to stay right out of anything to do with the election
''But the government heard the story and the Chief Minister asked me if it had any truth and I responded to her and gave her a report on quality management.''
