Michels Trenchless reflects on a milestone 2025 project.
As 2025 draws to a close, we look back on the growth of the trenchless industry and the innovation to complete projects that were once deemed unattainable. Michels Trenchless performed three extremely complex horizontal directional drills (HDD) for the Snowy 2.0 Pumped Hydro Project in New South Wales, Australia. Stretching from Lobs Hole to Marica, the HDDs are 2248m long. While this length is impressive, but not exceptional, for an HDD project, the difference in elevation measured 563m from the low side to the high side – a feat never previously accomplished by the industry.
In standard HDD profiles, elevation changes of about 50m between entry and exit locations are considered significant. Although the differential was considered too risky – and even impossible – by many in the industry, the Marica Road HDD was critical for the installation of electrical power, water, and fiber optic cables required to build and operate Snowy 2.0, the largest renewable energy project in Australia. With support from the US-based industry leader Michels Trenchless, it was determined that an HDD was the most effective approach to eliminate the need for 5km of roads and cuts through steep terrain in the environmentally sensitive area of Kosciuszko National Park. Michels drilled from the bottom of the hill to the top.
The significant change in elevation also posed a challenge in maintaining the drilling fluid “mud” pressure and flow due to the natural effects of gravity when drilling uphill. Forces are reverted to the drilling equipment due to gravity and friction from the dry bore hole. As fluid is pumped through the hole to lubricate and cool the drilling head and remove chipped rock and dirt that the drilling cutter head breaks up, the chipped rock and dirt are suspended in the liquid. This allows it to flow back out of the hole into the pit by the rig. For this elevation, maintaining the pressure and flow is difficult. To address these concerns, the project team installed a valve-closed rotary diverter on the lower entry side to direct the return flow cuttings and drilling fluids to a concrete containment pit where they are directed to a fluid separation plant for treatment.
Michels designed and fabricated two drill rigs, each with nearly 400 tonnes of push/pull force. Using the pilot hole intersect method wherein one rig drills from the entry side and the other from the exit side, the drill rigs meet in the middle at a predetermined location along the alignment. The pilot hole intersect method was selected over a traditional one-rig pilot hole method for its unique advantages for the project, including fluid pressure management, reduced risk of inadvertent returns, and steerability through hard rock present at the park.
Kosciuszko National Park is known for its unique, scenic landscapes and recreational and heritage values. Strict restrictions and environmental mandates were placed on how the work could be performed. In accordance with these rules, both rigs were set up inside large, engineered concrete pits to keep the drilling fluids separated from the ground. A gyroscopic combined with a magnetic tracking system allowed the project team to keep drilling operations on the necessary alignment and minimise human interaction with the forest between the entry and exit areas. Crews laid out coil wire in the straightest path to the centerline without removing vegetation.
The work site’s remote location posed logistical challenges to the transportation of parts and supplies, particularly specialised HDD tooling. Extensive planning was required to ensure all needed equipment, as well as any equipment or supplies that may be needed should unforeseen circumstances arise, was available on-site.
The project team collaborated with the project owner Snowy Hydro Limited and Future Generation Joint Venture to develop a safe, technically solid and constructable solution.
By developing executable plans to resolve extensive challenges without causing harm to individuals or the environment, the award-winning Marica Road West HDD project broadens the potential use of HDD to build and expand energy pipeline infrastructure in circumstances that may be considered undesirable.
For more information, visit michels.us