The fight to stop part of the Mt Roskill volcanic cone from being cut away to make way for a motorway extension has moved to the High Court.

Paul Cavanagh, QC, representing the Auckland Volcanic Cones Society, is appealing against an Environment Court ruling confirming a notice of requirement for an extension to State Highway 20 from Hillsborough Rd to Richardson Rd.

Mr Cavanagh told Justice Geoffrey Venning and Justice Robert Smellie that Mt Roskill was one of the few relatively unspoilt volcanic cones in Auckland.

He said the society was seeking to protect it from extensive cutting into its northern face for the proposed motorway extension.

The Environment Court had determined that the cone was of national importance as an outstanding natural feature under section 6 of the Resource Management Act, which protected it from "inappropriate" development.

Mr Cavanagh alleged that although the court had said that Auckland's volcanoes were regarded as "unique in the world, forming a cluster of small volcanic cones of fairly recent geological origin", it had nevertheless failed to apply the act correctly.

"It is submitted that the Environment Court failed to fulfil is legislative obligation by not engaging in a full and independent consideration of the protection required under section 6 of the act."

There was an obligation to give greater weight to matters of national importance than other issues.

"The integrity of a motorway extension to SH20 is not a matter of national importance," Mr Cavanagh said.

He said that the extension was given precedence over the cone.

"The court put the motorway first and the cone second, when it should have been the other way around.

"If you are building a road, you don't drive it through a heritage site.

"We are dealing with a motorway where the route can be changed but the mountain can't."

Suzanne Janissen, for Transit New Zealand, said that the Environment Court did not misapply section 6.

She referred the judges to a very similar case in the South island where the High Court had upheld a Planning Tribunal decision allowing the provision of log and coal facilities in Shakespeare Bay in Marlborough, despite the natural character of the area.

In that case the High Court said that natural character was only one of the matters of national importance to be taken into account.

"It is certainly not the case that preservation of the natural character is to be achieved at all costs," the High Court said in that case.

"The achievement which is to be promoted is sustainable management and questions of national importance, national value and benefit, and national needs, must all play a part in the overall consideration and decision."

Ms Janissen said the Planning Tribunal had said in that case that it was possible for a particular activity to assume a national importance.

"The view of the Environment Court that the SH20 project is a matter of national importance is implicit (if not explicit) ... in its decision,"

Ms Janissen said that the Resource Management Act did not require "absolute protection of the Mt Roskill volcanic cone at all costs."

She said the Environment Court did not "discard" the protection of the Mt Roskill volcanic cone as an outstanding natural feature but had considered carefully to what extent it should be protected to ensure sustainable management under section 5 of the act.

Robert Enright, appearing for the NZ Railways Corporation, said the wording of the act did not envisage absolute protection or preservation of the Mt Roskill cone.

It was simplistic and contrary to case law for the appellants to say that because the cone was of national importance, that trumped all, and that the proposed designation must give way to the need to protect the cone.

The judges yesterday reserved their decision on the case.

The case
Where: High Court at Auckland

Before: Justice Geoffrey Venning and Justice Robert Smellie.

What: The Auckland Volcanic Cones Society is appealing against a ruling that allows part of the Mt Roskill volcanic cone to be sliced away to make way for a motorway extension.

The parties: Auckland Volcanic Cones Society (Paul Cavanagh, QC), Transit NZ (Suzanne Janissen), NZ Railways Corporation (Robert Enright).

Decision: Reserved