Watercare’s new tunnel project is far from ‘boring’

There’s nothing dull about the latest engineering works to start in Glenfield, despite it being built with a boring machine.

In fact, the project is a Kiwi first and, in the process, it has creatively shaved time off and increased safety of the project.

Watercare’s wastewater upgrade on Wairau Rd is the first time a tunnel-boring machine will be used to lay glass fibre reinforced plastic (GRP) pipes.

There are many benefits to using a tunnel-boring machine as opposed to digging an open trench and laying pipe sections into place with a crane.

For starters, ripping up the road would mean shutting down Wairau Rd, an arterial route to the motorway in the heart of a business-rich area, for more than a year.

The closure of which, would draw a ‘‘mob’’ of angry vehicle drivers to the site, project engineer Dan Casey said.

Instead, traffic will be, for the most part, unaffected by the project and by not being on the road means greater safety for workers, Casey said.

Watercare’s project manager, Mahinda Attanayake said one of the other main gains is speed.

‘‘The tunnel boring machine has been imported especially for this project and will be able to drill up to 150 metres at one stretch, so we can get the job done faster,’’ Attanayake said.

‘‘We have spent a long time trying to work out ways that we can reduce the impact on the local community while we get this essential work done.’’

The tunnel boring machine works by creating a one-metre diameter tunnel before hydraulic pipe-jacking equipment thrusts a section of pipe into place.

While one person operates this part of the process, directing pipe with underground lasers, a separate machine pumps excavated

‘‘We can reduce the impact on the local community while we get this essential work done.’’

Mahinda Attanayake

earth, in a watery slurry form, to the surface.

Excess earth will be recycled where possible and put back down into the project, the rest will be removed.

The $14 million upgrade will run along Wairau Road to the Wairau Pump Station, accommodating an expanding population over the next 50 years.

A good wastewater network, is essential infrastructure to ensure North Shore’s beaches are kept healthy.

LAINE MOGER/STUFF The tunnel boring machine has been imported for a traffic-tricky project in Glenfield. The innovative use of this machine, buried 5 metres below ground, will avoid shutting down Wairau Rd and will speed up completion.