An update to the formal definition of microtunnelling means utilities can now adopt innovative, cost-effective solutions without compromising on quality.
Vacuum technology has been used successfully in microtunnelling projects in Australia for many years but has not previously been recognised in official definitions.
In September 2024, the International Society for Trenchless Technology (ISTT) formally included vacuum technology in its definition of microtunnelling – a change that follows efforts by Edge Underground Founder and CEO of OptionX Group, Stuart Harrison, in collaboration with the ISTT and the Japanese Society for Trenchless Technology (JSTT), to bring clarity to this issue.
“I was approached by a member of the ISTT to look at the merits of a change of definition in microtunnelling to include vacuum technology, which to me, was a huge compliment to be given that opportunity,” Mr Harrison said.
“For years, companies using vacuum microtunnelling technology have faced challenges during project tenders, having to submit non-conforming bids just to use this method, despite hundreds of kilometres of successful vacuum microtunnelling completed in Australia.
“To be given the opportunity to rewrite that definition and to put vacuum officially in as a microtunnelling method was an honour.”
Mr Harrison said that he was very excited to see vacuum technology be accepted worldwide.
“With the ISTT’s formal recognition, this technology can now be positioned on an equal footing, helping to streamline bid processes and allowing for greater competition in project tenders.
“This change represents a major development in the industry and could have wide-reaching implications, particularly as local Australian bodies and agencies begin to adopt these new standards. It also opens the world to the possibility of vacuum technologies and all their benefits.”
Vacuum power
Vacuum microtunnelling offers significant advantages, particularly in consolidated ground or rock. It immediately removes broken material from the bore, leaving a dry, stable tunnel and reducing the forces required to advance the pipe.
“The beauty of vacuum extraction is that it clears the path for the pipe, so you’re only dealing with skin friction,” Mr Harrison explained.
“In rock, it’s even better – you eliminate regrind and reduce wear, saving time and money. Vacuum’s ability to cut straight from the face gives you the minimum amount of pressure to be able to get a line from A to B.”
Although vacuum technology has been widely used in Australia, its global adoption has been slower. But with the ISTT now recognising vacuum extraction as a key method, the global industry is catching up to what Australian contractors have known for years.
Power in practice
Mr Harrison said that he recalled a project that he was a part of in the US in 2009 for BRH Garver Constructions, that exemplified the advantages of vacuum microtunnelling.
“They were doing a 450mm installation in a highly reactive clay and they had a 300t slurry microtunnelling machine. They started off on a 180m line, and halfway into that line they were stuck in the ground. 300t, nothing’s moving.
“They dug a shaft down at that point, and they created an interim shaft where they removed the tunnel head, and we went in there with an AXIS machine – a vacuum microtunnelling machine – and we set it up.
“The AXIS machine, much like the new AdaptX machine, sets out by putting a 350mm pilot line vacuum extracted through the ground. We pilot the next 90m of a 350 through the ground, and at no point do we come anywhere near our max thrust loads.”
Mr Harrison said that once this line was completed, Garver’s staff were concerned that the machine would struggle under the additional tonnage required for the next phase.
“We went about the upsizing process where we took it from 350mm to around about a 500mm bore to install the 450mm pipe. We did that the next day and at no point did we use more than five tonnes of jacking force.
“Now, when you compare 300t and you’re stuck in the ground to 5t and you’re moving freely, I think that says a lot about the benefits of a vacuum system. That is something that the world will continue to embrace and understand as we see more and more of this new wave technology hit the world market.”
Improvise, adapt, overcome
OptionX Group’s new AdaptX is uniquely positioned to take full advantage of the ISTT’s new definition.
Unlike other drilling machines on the market, its modular design means it can be adapted for a range of drilling methods to best suit the conditions at the site and client specifications.
It can switch between various methods – vacuum, slurry, auger boring, pipe jacking and more – depending on the ground conditions, making it the perfect choice for contractors.
“AdaptX isn’t just about vacuum extraction,” Mr Harrison said.
“It’s about giving contractors the flexibility to choose the best method. But when it comes to vacuum, AdaptX really shines.”
The AdaptX Mini features a torque range of 10,000 to 60,000 with a max thrust of 40t. The AdaptX Maxi has a max thrust of 125t and a torque range of 17,500 to 180,000. Other capabilities of the AdaptX include pressure air vacuum, HDD, displacement pilot, canopy tunnel drilling, pipe assist and pipe bursting. Torque and speed can also be adjusted to suit the job.
“With the updated definition of microtunnelling, utilities now have a clear path to awarding contracts that meet international standards and offer cost-effective solutions. This change enables utilities to consider bids that were previously non-conforming, reducing costs without compromising on quality.
“For end users, it means greater access to proven, effective methods that have long been used in Australia, now recognised as fully conforming.
“While the AdaptX machine offers multiple methods of operation, I firmly believe vacuum technology will prove to be the most effective. In fact, I’m confident we’re on the brink of a vacuum microtunnelling revolution! Nothing can compete with this technology, from consolidated ground to very hard rock.”
For more information, visit optionxgroup.com.au
