An elephant of a task was tackled at Werribee Open Range Zoo in Victoria, with contractor AHD Trenchless utilising a Prime Drilling horizonal directional drilling rig, acquired through the manufacturer’s partnership with TRACTO Australia, to construct a sustainable water supply needed for the zoo’s expanding habitat.
The $9.5 million recycled water pipeline project, delivered by Greater Western Water (GWW), Jaydo and AHD Trenchless, coincided with the arrival of nine Asian elephants at Werribee Open Range Zoo, providing a reliable source of Class A recycled water, reducing dependence on drinking water and freeing up allocations from local rivers.
With the zoo’s ambitious expansion plan in full swing, securing a sustainable water supply that met its strategic purpose as a world-leading conservation-based organisation aligned perfectly with the expansion of GWW’s recycled water network.
But behind this achievement lies an ambitious engineering feat: joining the zoo’s infrastructure to the newly constructed trunk main required a complex HDD crossing deep under the Werribee River.
This unique river crossing required a degree of skill and local knowledge of the surrounding geology, along with equipment capable of drilling a 1000mm bore through hard rock to house the new 710mm thick walled high-density polyethylene pipe.
AHD was up for the challenge and the project provided an opportunity to demonstrate the power and capability of the company’s flagship Prime Drilling PD150/90 drill rig.
The rigs was acquired by the contractor in October 2023 from TRACTO Australia, which is the local distributor of Prime Drilling equipment, as part of an exclusive agreement between the two German manufacturers.
Developed through a three-year collaboration with Prime Drilling, this state-of-the-art platform combines the agility of smaller units with the endurance of a Maxi Rig – setting a new benchmark in HDD capability and innovation.
This complex and challenging river crossing demanded both precision and power as it traversed 425m through river pebbles, clay, and extremely hard basalt at depths of up to 40m, and AHD’s deployment of the Prime supported locally by Tracto proved decisive, with the rig’s power and versatility central to the project’s success.
AHD Managing Director Anthony Doherty said these challenging conditions made it one of the longest and most complex drills undertaken by the GWW.
“As part of our HDD design and delivery process, we conducted detailed geotechnical investigations to ensure the HDD alignment targeted the right ground conditions,” he said.
“An absolute must to reduce risk and ensure the success of the project for all our stakeholders.”
Environmental and cultural considerations were integral throughout the project. The area surrounding the Werribee River is not only ecologically sensitive but also holds cultural heritage significance.
“We always maintain a high focus on avoiding frac-out’s that could damage the river or result in fluid leakage to the surface (that could) impact areas known to be rich in cultural heritage, so identifying the right drilling window is a critical step in our process,” said Doherty.
A further challenge was the machine’s proximity to a Viva Energy high-pressure oil pipeline, which required strict controls to be implemented, including vibration monitoring and advanced remote wireline gyroscopic tracking of the drill head.
Throughout operations, AHD’s guidance technician Will Boere monitored the drill head in real-time, providing stakeholders with continuous updates on the progress of drilling, as part of the risk mitigation process.
As the drill head approached the oil pipeline, AHD’s team performed potholing operations to successfully verify its actual 3D position confirming the strict design clearance parameters had been met.
“Drilling hundreds of metres from the rig and maintaining an accurate location of the drill head to within 10cm is all part of our everyday operations,” Boere said.
Construction within the zoo precinct also required delicate management. Much of the alignment ran along a back access track, which mean disruption to the zoo’s operations had to be minimised.
“It was quite unique to be working inside a zoo,” said Doherty.
“We had to coordinate around their access and operations, but they were great to work with and very helpful.”
GWW Senior Project Manager Alison Newland said the project benefited from early and sustained engagement with stakeholders, which helped shape the alignment and logistics.
Collaboration with Parks Victoria and the zoo ensured that future land use and animal welfare requirements were respected, while the recycled water quality was carefully aligned with the needs of the elephants and other zoo inhabitants.
The new system currently supplies the zoo with approximately 150 million litres of Class A recycled water per year, with the capacity to scale up to 400 million litres as demand increases.
The pipeline has been sized to accommodate future growth in the area, with further customers along the alignment expected to connect in time. Smart scheduling of irrigation within the zoo also helps manage peak demand periods.
Operationally, GWW will continue to monitor and maintain the system in line with its standard recycled water management protocols, ensuring water quality remains consistently high. Meanwhile, the zoo can divert its river allocations toward improving environmental flows across its wetlands and billabongs, enhancing biodiversity within its grounds.
The project forms part of a broader strategy by GWW to expand the use of fit-for-purpose recycled water sources across Melbourne’s west.
Doherty said the project stands as a compelling example of what can be achieved using trenchless technology, leveraging strategic partnerships and committing to sustainable solutions.
“It’s really rewarding to know that our work has contributed in a small but important way, providing a critical leg, in supplying a sustainable water supply to help the zoo achieve its purpose of providing profound animal encounters that connect people with wildlife,” he said.
“The new 21-hectare Asian Elephant habitat is truly inspiring.”
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This feature also appears in the September edition of The Australian Pipeliner.