Dec 2020 tower ad (left)
Dec 2020 tower ad (right)

The edge over tough microtunnelling projects

Edge Underground takes on microtunnelling projects across the country, continuing to philosophise that no job is too hard or impossible.

As the trenchless industry continues to expand across Australia, site conditions that make microtunnelling projects seem high risk or impossible are creating long-term limitations on the work available and, in turn, damaging the industry’s growth. Edge Underground Managing Director Stuart Harrison says at least half the projects the company undertakes are those no other contractor wants due to concerns over project success.

“Part of the reason that we take on these jobs is because we’ve got a belief in our own ability, and the equipment that we run,” says Mr Harrison.

“But also, we feel like it is somewhat of a responsibility to show people what is possible. At the end of the day if contractors keep turning around saying, ‘Oh no, there’s a problem, you need to dig this up’, or say straight up that the project is going to be too difficult, we’re essentially cutting down the scope of our own industry.

“We certainly don’t look at it that way. We look at every job as being achievable, it’s just a matter of finding a way and a means to complete that job successfully and achieve that outcome. We go out there with a good attitude and with state-of-the-art equipment and understand all the different aspects of a job and the complexities, and still find a way to get it done.”

Equipment is key

In all microtunnelling projects – although especially in high risk conditions – having the right equipment is critical to success.

“One example of this was a project in Donnybrook, Victoria, which no other contractor wanted to take on due to the ground conditions (a combination of extreme hard rock with seams of clay and fractures), which had a high risk of wedging occurring,” says Mr Harrison.

To counteract this problem, Edge Underground used the AXIS laser guided boring system, allowing the team to retract the drill head to complete a pilot line and inspect the ground to confirm conditions. In doing so, Edge Underground did not go into the project with incorrect or partial geotechnical information and, instead, could configure the reaming tool to best suit the pipe jacking conditions required.

Mr Harrison says this feature means if conditions do change again further down the installation, the drill head can be retracted and changed out to something more suitable so drilling can recommence from the same spot. This capability is not found in other machines, which increases the project’s risk as it would require the drill head to be dug up from above, increasing time and costs.

The drill head of the AXIS can retract, allowing the contractor to do a pilot line and inspect the ground.

Considering alternatives

While factors such as the right microtunnelling equipment and dedication to finding a solution to a difficult project go a long way in successfully completing high risk jobs deemed impossible, sometimes microtunnelling is not the best option for the task at hand.

Mr Harrison says when this is the case, it is the duty of the contractor to let the project manager know.

“We do our best to try and speak to contractors or an engineer who’s designing a project about site-specific issues about what we can offer,” he says.

“We’re also happy to let them know that maybe what we’re offering isn’t the best solution on their job.”

Trenchless technology comprises a broad category of equipment and solutions and within the sector, any trenchless professional can discuss variations in technology that all present varying strengths and limitations. Edge Underground understands using the wrong tool in an application can result in a disappointing outcome, both financially and structurally.

“So wherever we can get more industry professionals assisting to get designs right, relative to the desired outcome, I think we help our industry grow, because people that we’re working with gain confidence that they’re going to prescribe something that will be successful,” says Mr Harrison.

“I think everyone in the industry has the burden to assist that process, and help clients come to some sort of a great outcome from our advice, from what we’re putting in.”

This article was featured in the September 2020 edition of Trenchless Australasia. To view the magazine on your PC, Mac, tablet or mobile device, click here.

For more information visit the Edge Underground website.

If you have news you would like featured in Trenchless Australasia contact Assistant Editor Sophie Venz at

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