Our tunnel boring machine (TBM) has today broken through the Khyber Pass Road section as it lays the new Hūnua 4 water pipeline.
Just after 11.00 am this morning, the seven-metre-long TBM called ‘Amiria’ completed its 400m journey under Khyber Pass Road to the reservoir in Symonds Street. The TBM was lowered into place on the night of April 30.
The TBM pushes a section of pipe into place.
Without it, the pipe would have had to be laid using an open trench method, which would have caused traffic chaos in this busy area of the city.
Watercare Hūnua 4 project manager David Moore says the tunnel broke through earlier than expected: “The TBM or ‘mole’ has worked its way through the sediments rocks known as ‘tuff’ very easily.
"We’ve had no major break-downs and have encountered no unexpected hazards such as buried lava bombs (rocks).”
Contractor McConnell Dowell has operated out of a small site underneath the Newmarket flyover and just metres from the traffic lights beside the motorway intersection. Trucks timed their deliveries of pipe sections to avoid peak hour traffic.
At times, the pipe varies in diameter as it travels across Auckland, from 1.6 -2 metres. This final section of pipe will transport 120 megalitres per day (MLD) or 48 Olympic swimming pools per day.
The completed Hūnua 4 pipeline will run from the Redoubt Road water reservoir in Manukau to the Khyber reservoir complex in Grafton. Construction began in 2008, with the first 28km (and in use) running to Epsom.
Now the Khyber Pass tunnel section has been completed, there are just 2 more tunnel sections to be built: along Manukau Road to Ranfurly Road, Epsom and also under the southern motorway between Newmarket and Khyber Pass Road.
The completion of the new watermain will ensure that we can continue to provide uninterrupted, Aa-grade (top quality) treated water as Auckland grows.