McConnell Dowell has started excavating a 250m long outfall tunnel for the US$24M first stage of a treated sewage disposal project on the coast at Dunedin, New Zealand.
The Australian contractor is using a Herrenknecht AVN 1500T series slurry shield – named ‘Yvonne’, after the wife of Dunedin City Council wastewater and stormwater operations team leader, Brian Turner.
The 1.84m o.d. tunnel will be bored from St Kilda beach at Dunedin. Upon completion of the concrete lined tube, the contractor will place a 1400mm diameter PE pipe to run 940m from the end of the tunnel to discharge treated effluent farther offshore, about 1km out to sea.
McConnell Dowell built a special jacking pit near the Tahuna sewage treatment station to launch the 35t TBM, which suits up to 1500mm i.d. pipes.
