The council asked Cardno BTO three specific questions about long-term options:
* to determine whether it was viable to continue with the current plant.
* if that was viable, then what options were there to maintain satisfactory performance and which could be in place within two years.
* and if the plant was not viable, then what sort of plant would be needed and how big would it need to be.
It has since been found that the treatment plant failed to meet some resource consents, prompting Horizons Regional Council to seek an enforcement order from the Environment Court.
Horizons said the order would establish an agreed plan with the WDC to overcome the odour problem and would be monitored by the court, as well as providing a timeline to ensure the WDC was doing all it can to resolve the issue.
With the release of the review today at least one district councillor is calling for heads to roll.
Councillor Michael Laws said in his view legal action has to be brought against those firms and individuals who "have saddled Wanganui with a sewage plant that doesn't work, and won't work".
Mr Laws was mayor at the time the council commissioned a review of the sewage treatment plant design in 2005 and he also officially opened the plant in September 2007. But yesterday he said it was clear that the expert advice to council was "as wrong as wrong can get".
He said given that Cardno BTO had already said the plant will never work, the obvious question was who said it would.
"The liability goes back to those engineers and designers and senior council management who informed the governance team that it would work. Just as worrying is the fact those experts had their assumptions peer-reviewed by other experts and they got it wrong too.
"To be fair to senior management, they were simply taking the experts' advice," Mr Laws said.
He said council should get lawyers to look at the legal liability.
"We did it effectively with the Splash Centre and got settlement for the fix-up. We did it to get the Government to cough up the money owed us with the airport. We need to do it now, to defray the inevitable cost associated with getting a new plant operational," he said.