By WAYNE THOMPSON
Manurewa residents say a wall built to protect the Auckland Regional Botanic Gardens from motorway noise is bouncing the sound into their homes.
They say traffic noise in the neighbourhood has increased substantially since the regional council built the 3.5m wall in January.
Made from steel panels over a
50mm core of insulation foam, the wall runs for 500m along the botanic gardens boundary with the Southern Motorway.
A residents' group is calling for the structure, which they say is as ugly as a prison wall, to be demolished.
But the ARC, which is responsible for environmental planning, is promising instead to cover the wall with a rare vine, which it says will help to absorb sound.
One of the residents, Ken Stevens, said their cause had now been bolstered by the Manukau City Council, which last year gave the ARC a resource consent to build the wall.
Mr Stevens said the group had seen a letter from Manukau to the director of the botanic gardens, Jack Hobbs.
The letter says the city should review the resource consent or the ARC should make a fresh application, open to public objections.
The letter says information received since granting the consent would have made the city handle the bid in a more open manner.
The consent was processed as a non-notifiable application, which ruled out public opposition.
Then, Manukau was told by acoustic experts that the wall would have no noticeable effect on noise for neighbours on the other side of the motorway.
But in a letter to Mr Hobbs, the Manukau team leader for resource consents, Richard Ritsma, says two experts had said properties with a direct line of sight to the wall were likely to experience a noise increase of 5 to 7 decibels.
This was a tenfold increase over that stated by the ARC's acoustic consultants.
Mr Ritsma said talks were being held with the ARC over the resource consent conditions and the prospect of further acoustic tests.
Mr Hobbs said the wall was doing a fine job in reducing traffic noise to the native bush area.
He said that in 18 months it would be covered by a rare, evergreen vine "which we believe will also mitigate the noise."
