L to R Watercare's Chris McCarthny, Emmanuel Vaki and Shayne Cunis beside Domenica's 2nd breakthrough point
She’s done it again! Domenica—the Central Interceptor’s micro-Tunnel Boring Machine has broken through to the Haycock
Avenue shaft, Mt Roskill after travelling 715m from Dundale Avenue.
It’s the second and shortest drive so far, since Domenica began her journey in July last year as she lays a 2.1m branch
sewer pipe to connect to Watercare’s giant wastewater tunnel, the Central Interceptor. Water and spoil gushed as
Domenica broke-through, directly on target. The project is being delivered by Ghella Abergeldie (GAJV) and will
significantly reduce wet weather wastewater overflows into central Auckland waterways when it’s completed in 2026.
There were loud cheers from crews, who gathered around the shaft and watched a live stream of the breakthrough operation
happening 30m below ground.
Watercare executive programme director Shayne Cunis says the drive was completed efficiently, safely and ahead of
schedule: “The tunnelling crew learnt a lot from the first drive and achieved breakthrough almost a month ahead of
schedule.
“At one point, Domenica was tunnelling 22m and laying seven pipe rings per day—which is 25 percent faster than our first
drive.”
One of the innovations seen this time, was the use of “double skips” which meant twice as much spoil could be removed
from the shaft.
Domenica will now be lifted out of the shaft and refurbished before being dropped into the Dundale Avenue shaft to begin
tunnelling again to Miranda Reserve, Avondale— just under 1.2km away. This will be the longest m-TBM drive on the
project and is likely to be one of the longest single drives by a m-TBM in New Zealand.
Meanwhile the 5.4 diameter Tunnel Boring Machine (TBM) called Hiwa-i-te-Rangi began digging the 14.7km long main tunnel
in August from a site next to Watercare’s Māngere Wastewater Treatment Plant.
COVID-19 caused minor delays in March but since then, the machine has been making good progress, travelling around 16m,
and installing six to eight tunnel segment rings per day. The TBM is currently 35m underneath Ambury Regional Park and
is due to begin crossing the Manukau Harbour in August, before reaching Grey Lynn in 2026.