Controversy is flaring anew over Auckland's $2 billion Waterview motorway project as Transport Agency contractors propose changing the location of a ventilation tower for the twin tunnels.

If accepted by the community it would require a variation to a board of inquiry decision that approved the project subject to building the 15m tower on the other side of Great North Rd from Waterview Primary school.

The agency confirmed yesterday it was seeking community views on whether building the stack on the school side, but further north than proposed, should be investigated in detail to avoid cutting a disruptive trench through the busy arterial road.

It said the idea had emerged since the board decision, after contractors opted for tunnelling technology capable of boring under Great North Rd without need for "cut and cover" sections at each end of the tunnels.


Regional highways manager Tommy Parker said the technology would be less disruptive than a proposal presented during a fast-track national consenting process this year, wherever the tower was built.

But he believed there would be benefits for the community and the agency in exploring an option of not having to put the tower at the edge of the Waterview Glades reserve, above Oakley Creek.

Although the conservation group Friends of Oakley Creek is reserving its views on the new proposal, Northwest Community Association convener and Waterview resident Bill McKay said it ignored visual concerns acknowledged by the five-member board of inquiry.

He said that although the proposal may cause less disruption during construction, his community risked having to live for many years with a more visually obtrusive structure which threatened to become "a symbol of Waterview".

The site preferred by the Government-appointed board in response to expert witnesses who supported the community's concerns was on the inside of a curve in Great North Rd "so you are not looking straight at it when you are coming up the road".

But Mr Parker said the new option could have less visual impact than the original proposal, which would have been only metres from the primary school's boundary, if the venting tower could be built between the portals of the two tunnels.

That is what the agency intends doing at the southern end of the tunnels, in Owairaka's Alan Wood Reserve, as shown in an artist's impression provided to community groups.

The agency says it wants to gauge the views of the Waterview community before providing any comparable images for the northern end.


Oakley Ave resident Caroline Botting said she would be concerned about air quality from a venting stack on the school side of Great North Rd, as well as greater visual impact.

But Mr Parker said the agency had analysed all potential locations in satisfying itself there would be "no detrimental impact in terms of air quality" from a 15m tower.

A project official said the contractors were sensitive about "opening up old wounds" by raising the new option, but did not want to be accused of disrupting Great North Rd unnecessarily once construction had started.

He said a trench connecting the tunnels to a tower on the site approved by the board would take a year to 18 months to dig.