Web Tower: Aug – Oct ’19
Web Tower: Aug – Oct ’19

Maxibor uses HDD for NBN Co installation

Trenchless contractor Maxibor has used horizontal directional drilling (HDD) to install a fibre link for NBN Co in Scotts Head, New South Wales.

A map of the original route (green) and the new route (red). Image courtesy NBN Co.

The installation, which passed under a river and coastal wetlands, will enable residents and visitors to the town access to the nbn™ network.

The installation had been planned to run along a 15 km route from Macksville to Scotts Head via the Pacific Highway; however, the design presented issues that would have involved difficult bridge crossings and caused significant impact to traffic.

“We would have had to shut down sections of the highway and bridges,” said NBN Co Deployment Manager – Rural North Steven Hasselbach.

“If we had gone down that route, not only would it have taken a lot longer, it would have cost us about 20 per cent more.”

The HDD in operation. Image courtesy NBN Co.

After consulting the area’s NSW Regional Deployment Project Officer Pat Friend, a new route was developed using quiet back roads in the area, along with two sections of directional drilling.

Each section used a single 500 m bore shot, one running under Warrell Creek and the other under coastal wetlands in the area, reducing the challenges of the project.

A worker monitors the HDD’s operation. Image courtesy NBN Co.

“The new route allowed us to avoid many of the risks we would have faced on the main road, as well as a series of difficult bridge crossings,” said Mr Hasselbach.

Specialist operator Maxibor Australia used a 13.5 t directional drill to bore a path for the fibre-encasing conduit 15 m below Warrell Creek.

The HDD rig faced a tough mixed geology, comprising dirt, cobblestones and bedrock; the bedrock was a particular challenge, with a compressive strength of 180 MPa – equivalent to the hardness of granite.

The progress of the drill is monitored from a dinghy.

In order to make sure that the drill head remained at the right depth and direction, it was monitored using a magnetic guidance tool and tracked beneath the riverbed by a worker in a dinghy.

The drill was able to achieve a pace of 3 cm/m, taking just 10 days to complete the job.

“It’s innovative solutions like these bore shots, coupled with the expertise we have on the ground all around the nation, that’s allowing us to get on with the job of connecting Australians to services over our network,” said Mr Hasselbach.

For more information visit the NBN Co website.

If you have a project you would like featured in Trenchless Australasia contact Journalist Chloe Jenkins at cjenkins@gs-press.com.au

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