A new pipejacking record has been set on Watercare’s Hunua 4 watermain project in Auckland today.

Amiria the tunnel-boring machine (TBM) broke through at Khyber Pass Rd, setting a record of 1216 metres for the longest single drive in the southern hemisphere by a TBM greater than 3 metres diameter.

Contractor McConnell Dowell broke its own pipejack record – for the Christchurch Ocean Outfall project in 2007 – by 345 metres.

McConnell Dowell project manager Richard Atkin says: “This record achievement demonstrates the skill and experience we have in our tunnelling teams, as well as our commitment to working through challenges and delivering for our client.”

There is just one more tunnelling drive to go in the final section of the watermain project, which will connect the Redoubt Rd and Khyber Pass reservoirs. At 1296m-long, this drive will break the record again.

Amiria was named by a child in Starship Hospital. It is the te reo Māori version of Amelia, which means hardworking.

“She’s certainly lived up to her name,” Atkin says. “In this tunnelling drive she bored through more than a kilometre of basalt rock, and curves with a radius of 750m, which placed pressure on the interjacking stations.”

Watercare project manager David Moore says: “The beauty of this part of the project is that we’ve built this huge piece of infrastructure and very few people even knew it was happening. We tunnelled from right next to the new Westfield Newmarket mall under New Zealand’s busiest road – the southern motorway – to Khyber Pass Rd without disturbing the public.”

The 60-tonne, closed-faced Herrenknecht machine bored at depths up to 30 metres below ground level.

Most of the 31-kilometre watermain has been laid with open trenching, but tunnelling was chosen for most of the final section between Market Rd and Khyber Pass to minimise disruption to a busy urban area.

The project, which caters for Auckland’s growing population and adds resilience to the water network, has been completed in 11 sections and will be finished next year.

NOTES:

• About 25,000 tonnes (or 8500m3) of material was excavated during this record-breaking drive. That’s about the same as two and a half Eiffel Towers or 300 blue whales.
• The Herrenknecht AVN 2500AB micro-tunnelling machine is controlled by an operator from a small pilot cabin above ground at the Broadway site.

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