In New Zealand, North Shore City has said that the estimated cost of its planned 2.6km long wastewater tunnel and 2.8km long tunnelled sea outfall have risen by US$13.6M to US$67.5M, and attributed it to inflation and a booming construction industry.
The project is due to start in 2008 for completion in 2010. The new tunnel and outfall will take highly treated effluent from its existing wastewater treatment plant 2.8km out to sea, replacing an existing outfall built in the 1960s that discharges only 600m from the shore.
In 2004, a cost estimate indicated a US$54M completion cost, but Tony Barker, the city council’s infrastructure and environment committee chairman, said the council is concerned that inflation and a busy construction sector has increased the project’s estimated cost. Other factors contributing to the revision are higher tunnelling costs and an increase in the length to be tunnelled as opposed to trenching. Site investigations have also indicated that conditions could be more difficult than first thought. Barker said: “It’s unlikely that the project can be deferred or reduced in scope, and until expressions of interest and a final fixed price contract comes back from potential contractors, the final figure for the project is unknown.”
