KEY POINTS:
Work on replacing the concrete sewer across Auckland's Hobson Bay with a 3km tunnel will start this year.
The 90-year-old sewer, which cuts across the bay, will be demolished as part of the $118.6 million project let by Watercare Services.
Joint-venture contractors Fletcher Construction and McConnell Dowell hope to finish in 2010.
The old sewer has reached the end of its economic life and has long been an eyesore for the hundreds of homes and public viewing points which overlook the bay.
Its demise will also open up one of the biggest bays of the Waitemata Harbour to greater use by small craft and, possibly, a ferry service, says a Hobson Ward member on the Auckland City Council, Richard Simpson.
"Hobson Bay can take its place as part of the bigger vision for Auckland's waterfront. We would have a magical place surrounded by Parnell, Orakei, Meadowbank, Remuera, Newmarket; opening up the opportunity to get small ferries into these suburbs and connect them with walkways and cycleways."
Auckland Rowing Association is leading the charge to develop the bay as a recreational marine park when the sewer goes.
"It is a fantastic opportunity for paddling sports - rowing, canoeing and waka ama (outrigger canoe), as well as small yachts and Sea Scouts," said association chairman Brian Parr.
"It will be tremendous to have such a facility right in the centre of Auckland."
Watercare decided on a tunnel after public feedback on three alternatives: encasing the old sewer in a new concrete jacket, replacing it with a shallow buried sewer, or a tunnel.
Encasement was the cheapest option in a 2002 estimate of $26.5 million versus $47 million for a tunnel.
But Watercare says the scale and the scope of the project has changed.
In late 2005, as a result of Auckland City Council, Metrowater and Watercare joint planning, the decision was taken to increase the diameter of the tunnel and make other changes.
This added a further $15 million and added to the cost were demolition of the old main and the price escalations that have hit most big Auckland works projects.
Watercare chief executive Mark Ford said awarding the contract was a significant milestone.
Replacing the sewer main with a larger capacity tunnel for carrying and storing wastewater would meet projected growth in the area.
Mr Ford said it would help the marine environment because it would practically eliminate wastewater overflows into Hobson Bay, which is part of theWaitemata Harbour.
The 3.7m-diameter concrete-lined tunnel, passing about 30m under the bay's mud and rock, would also open up the bay for recreational purposes and improve views of the area, said Mr Ford.
The main carries a quarter of Auckland's wastewater to the Mangere Wastewater Treatment Plant.
Watercare provides bulk water and wastewater services to the Auckland region and the project price includes its costs and risk provision and is allowed for in its water asset management plan.
Mr Ford said the project's boosted capacity offered significant stormwater and wastewater management benefits to Auckland City Council and local network operator Metrowater.
In December, the Environment Court approved revised resource consents for the project which had been granted nearly two years earlier by Auckland Regional Council and Auckland City Council.
Four residents and the Ngati Whatua o Orakei Reserves Board had appealed to the court against some aspects of the proposed work in the bay and the Orakei ridge.
