NEWS RELEASE

Future proofing at treatment plant

June 13, 2006

A $16.2 million contract to increase the capacity and efficiency of North Shore City's wastewater treatment plant at Rosedale has been awarded to New Zealand-based contractor Fulton Hogan.

Work on the project, known as the Stage 5 upgrade - inlet works and primary sedimentation tanks - is expected to start next month and finish in December next year.

Chairman of the council's infrastructure and environment committee, Tony Barker, says the upgrade will more than double the capacity of the inlet works and the primary sedimentation tanks; improve efficiency; reduce the amount of screenings that need to be disposed of; further improve reliability; and help to reduce odours.

The structural work will future-proof the plant for another 20 years, based on current population growth projections, and the mechanical work for a further decade. After that time, additional mechanical screens will be needed to further expand capacity.

"The work we have been doing at the plant over some years gives the city a highly efficient, state-of-the-art plant that makes a major contribution to our environment - and that includes helping to keep our streams and beaches clean," says Councillor Barker.

The upgrades also ensure the "Rosedale lake" (oxidation ponds), previously needed as a part of the treatment process, continue to be used simply as a store for high quality treated effluent before discharge at sea.

The extensive structural and mechanical work involved in the project will boost the plant's capacity by 70 per cent, from 2.4 cubic metres per second (cumecs) to nearly 4 cumecs.

Much of the work involves the building of two large concrete sedimentation tanks, each measuring nine by 51 by 4.5 metres deep, the equivalent of two Olympic swimming pools. The covered tanks will provide greatly increased treatment capacity and will be equipped with biological odour control systems.

For additional odour control, a new biofilter will be built to deal with possible odours from the inlet works and primary sedimentation tanks.

New mechanical and electrical systems that operate the many new pumps, valves, gauges and circuits in the plant are also included in the contract.

The Stage 5 upgrade follows a series of upgrades since 1993, with the 1996 Upgrade Number 2 at that time boosting capacity by 70 per cent.

ENDS

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