Tauranga city councillors are going back to square one on the tsunami sirens issue after learning the contracted system will cost $2.3 million when its budget was $1.05 million.

Councillors agreed on Monday to have a workshop to discuss the planned tsunami system including whether the council actually needs them and when they should be built.

Councillors will hold a workshop to discuss tsunami sirens.

Against opposition from ‘air raid' siren proponents councillors Bill Grainger and Murray Guy, the council in July 2012, contracted Meerkat Systems to design and obtain consent for a tsunami warning system. The council has spent $190,000 so far.

In February 2013 council staff learned Meerkat could not deliver the required specification of 80 per cent coverage in outdoor at risk areas on budget.

City Engineer Howard Severinsen was grilled by councillor David Stewart over the report, which David described as alarming, disappointing and almost embarrassing that the city council has got to the situation it is in.

'Finding out Meerkat Alert Systems only give 50 per cent coverage? When did we find that out? How come we have got all the way down this track and we have only just found out, recently obviously, we weren't getting what we thought we were getting. How did that happen?”

Acoustic consultants and noise control engineers Marshall Day examined the Meerkat system for the council and the staff became aware of problems just before Christmas, says Howard. But it wasn't until February Tauranga City Council staff found out Meerkat couldn't deliver with the system they designed.

'We were promised a system that would give the 80 per cent design-build, turnkey operation,” says David.

'Was the meeting before Christmas, the meeting with the Meerkat versus the wind up World War Two ones - did we not know at that stage that they weren't able to give us what we thought?”

While it was disappointing to learn the Meerkat system didn't perform, Howard says he's extremely pleased they did the due diligence and had it checked by the acoustic consultants.

The Meerkat system also raised resource consent issues including that public notification would be required.

'Where was the professional planning advice on this?” asks David.

'Couldn't we get that advice from our staff before we put an application in, that it was likely to be a notified one and that we were likely to run into problems - without going all the way down the road that we have, putting an application forward and then having that come back at us, that we are up against the wall.

Howard says council did take advice on how the application was likely to be treated by planners.

'In their defence a planner can't say ‘I will treat this application in this manner', before they see the application,” says Howard.

David says council staff could have got a 'steer” before the application was lodged.

'We could have got a pretty good steer that we were running into problems before, as you would do if you were putting forward your own resource consent application.

'So why couldn't we have got that, and then come back to council and we could have weighed up our odds and probabilities?”

Meerkat systems are installed in Rodney, Christchurch and Waitakere, and Howard says they were confident they had overcome any planning hurdles.

Meerkat employed a reputable Tauranga based planning company to put the application together.

'The signals were reasonably positive until we found out that the wheels were falling off it,” says Howard.

The last question was about the worst case tsunami heights, a 13 metre tsunami from the Kermadec Trench.

Previous information to council is the biggest risk of destructive tsunamis is from further away, like Chile where there will be plenty of warning, says David.

The Kermadecs are considered less of an actual tsunami risk for the Bay of Plenty because of the north south direction of the trench, so big waves will travel east/west away from it, rather than towards New Zealand.

'I just feel unsettled that the information we get and put faith in is changing from one thing to another without much explanation,” says David. 'How credible is the status of the information we have got.”

Councillors agreed to stop the Meerkat contract process and hold a workshop.

Councillors are questioning the worth of tsunami sirens with some saying they are a comfort blanket.

Councillor Terry Molloy says they are as much use as an ashtray on a motorbike.