Start date announced for council's largest ever wastewater project

A January 2008 start date has been confirmed for construction of North Shore City Council's Rosedale Wastewater Treatment Plant outfall project following the awarding of the $91m contract.

The successful tenderer, McConnell Dowell Constructors Ltd, will undertake preliminary work between now and Christmas, with physical construction starting early next year. It will be completed by mid 2010 to meet Auckland Regional Council requirements.

North Shore City's wastewater networks project manager, Dave Woods, says the new outfall is a necessity to meet the future needs of our growing city.

"Once the project is completed, high quality treated effluent will be transferred from the treatment plant, and discharged 2.8km out to sea into the Rangitoto Channel."

The route stretches 2.6km from the treatment plant to Mairangi Bay, running deep underground beneath streets, parks and reserves, a limited number of commercial and residential properties, as well as council owned land.

A tunnel will be bored from the treatment plant to a point offshore, where it will rise to join a section of pipe buried in the seabed.

There will be minimal disruption to the community with the main surface work to be located at the Rosedale Treatment Plant, and only one access shaft to be built at the Mairangi Bay foreshore.

The proposed route for the western part of the outfall has been simplified and straightened, resulting in a $7m cost saving for ratepayers, and allowing the whole length of the land-based portion of the outfall to be tunnelled at least 25 metres underground.

The new tunnel will have a lifespan of at least 100 years, with up to six times more capacity than the existing outfall. At its discharge point, diffusers will ensure the high quality treated effluent is widely dispersed.

The existing outfall, 600 metres offshore from Kennedy Point, is nearing the end of its lifespan, is too small to cope with further growth in the city and has had major repairs in recent times.

ENDS

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