Hunua 4 Section 11 Watermain Achieves Important Milestone in Auckland, New Zealand

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Watercare and McConnell Dowell’s TBM “Amiria” has been launched under the busy Khyber Pass Road in Newmarket, on a 390m journey to Watercare’s Khyber Pass Reservoirs in the final section of the Hunua 4 watermain. This is the first of three drives for this 3m diameter slurry TBM, which is being driven through volcanic deposits in central Auckland. The project combines traditional cut-and-cover methods with trenchless tunnelling to install the 3.6km, 1.6m diameter steel pipeline.

Future tunnel excavations will also include a 1.3km drive under the busy Manukau Road, and a 1.2km drive under State Highway 1 along the flank of Mt Eden. The tunnel geology primarily consists of basalt, volcanic tuff/tephra and alluvium. A total of five shafts will be utilized for the tunnel construction.

In addition to the tunneled sections, there is approximately 720m of cut-and-cover pipeline installation. A total of nine valve chambers for flow control/isolation and air relief will also be constructed.

The completion of the new watermain will ensure that Watercare can continue to provide uninterrupted, high-quality water as Auckland grows. McConnell Dowell and their permanent works designer McMillen Jacobs Associates are proudly delivering this design-and-construct project to Watercare.