McConnell Dowell Constructors will use microtunnelling techniques to build the landward section of an ocean outfall that will be built as part of a US$58.25M contract with Christchurch City Council.
The firm said microtunnelling was chosen after it was asked to consider tunnelling and conventional pipe-laying. About 2.3km of 1.8m diameter tunnel will be excavated between 6m-8m underground using a micro- tunnelling machine. The tunnel, containing a concrete pipeline, will run from the city’s oxidation ponds under the Avon-Heathcote estuary and South Brighton spit where it will link to a conventional offshore outfall.
The firm beat off a challenge from four other contractors to win the project. Christchurch mayor Garry Moore said: “This is an outstanding solution. Not only is it the best financially for the city, it is the most environmentally sound and least disruptive solution for the local community and recreational users in the vicinity of the pipeline route.”
Construction was due to start in October for completion in September 2008.
