There's support for an inquiry into the failure of Whanganui's wastewater treatment plant - but the district council is uncertain what form it should follow.

After two hours of sometimes confused debate yesterday afternoon, the majority of councillors indicated they supported an inquiry. But who will head it, what it will seek to answer and how much it is likely to cost are questions they want answered.

The call for an inquiry is in a motion council has had on its books since June 2013 before it was overtaken by the legal action against plant designer, MWH.

It was back on the agenda yesterday when council decided to hold a workshop which will be open to the public.


The Wanganui Ratepayers' Association presented a 1023-signature petition asking council to "urgently initiate" an independent inquiry and suspend any spending on the new $42 million plant until the outcome of the inquiry was known

Chief executive Kym Fell had been asked to prepare a budget and timeline for an inquiry. He told councillors some information could not be given to any inquiry because it was part of the confidential settlement reached with MWH, and he suggested councillors considered the costs of an inquiry.

Legal and technical advice for the litigation against MWH cost council more than $1.2 million and - given the complexity of an inquiry - he said that would likely cost hundreds of thousands of dollars.

"We have indicative costs and these could be up to $300,000," Mr Fell said.

The councillors were at odds over what the inquiry would be expected to achieve, but they were adamant it was not about naming or blaming people who may have been involved.

Mayor Annette Main said: "What do councillors want to know about the plant's failure, who was responsible for it and was the correct advice given?

"We know staff worked very hard to make that plant work but it didn't - so until we know what you want to find out, we're going nowhere," she said.

Councillor Helen Craig said that guidance would need to give a direction of what councillors thought was independent advice and whether or not any proceedings were held in public. She said a workshop was the best way to "define these parameters".

Councillor Ray Stevens moved that council not proceed with an inquiry but he did not get support for that.

Councillor Hamish McDouall said the original call for an inquiry was about finding if council was under undue influence or if officers "went beyond their brief".

"It's about processes within the council back in 2004. We need some sort of inquiry - we've wasted $25 million on the original plant and we need to know why.

"It wasn't until 2012 that I first learned there was a problem with the plant, was told then it was not working and that there had been waste discharged directly into the sea. So I want to know what council's errors were."

Councillor Rob Vinsen did not believe the costs floated by the chief executive were realistic.

"It's not the David Bain inquiry we're talking about. It should take no longer than a month and that's tens of thousands of dollars, not hundreds of thousands."

Councillors Jenny Duncan and Philippa Baker-Hogan backed an inquiry. Mrs Duncan said a workshop would be worthwhile to refine an inquiry's terms of reference. Mrs Baker-Hogan said it was a matter of finding if advice council received was sound, if the old plant would have worked or not and could it still work.

Councillor Martin Visser said the debate over the issue would go on indefinitely "unless we try to settle the minds of the community".

Ms Main said it was key to find out why the council said yes to the original design "and how come we pumped waste into the sea without council knowing about it".

"We've got a new plant that will work and council has agreed to that around this table. We've done everything we can to make sure this doesn't happen again."

But she supported Mr Stevens' motion because "it's [an inquiry] not the best thing for our community".