Snowy 2.0 – Marica Road West HDD: Engineering Innovation in Extreme Terrain

Abstract

The Marica Road West Horizontal Directional Drilling (HDD) project is a critical component of the Snowy 2.0 renewable energy initiative in Kosciuszko National Park, New South Wales, Australia. The project involved the design, drilling, installation and securing of three separate 2,240 metre long, 340 millimetre diameter threaded steel casings via HDD for power, water, and communications. The Marica Road West HDD is notable for its technical complexity, primarily due to the environmentally sensitive escarpment, with a 563 metre elevation change between the two sites, making it one of the most challenging HDD projects completed in Australia. This extreme elevation difference presented significant engineering challenges, including managing borehole fluid, ensuring borehole stability across variable geological formations and controlling high groundwater inflows. To overcome these challenges, Michels implemented innovative techniques, including a dual-rig intersect method which was essential to operate within allowable drill string parameters and the deployment of a custom-built rotary diverter for effective borehole fluid management. The project was executed within the environmentally sensitive Kosciuszko National Park, necessitating strict environmental controls with constructing a substantive groundwater containment system to prevent ground disturbance, and ecosystem impact. The successful completion of the Marica Road West HDD demonstrates significant advancements in HDD capabilities, particularly in managing extreme elevation differences and complex geological conditions within highly sensitive environmental areas. These findings are important to the trenchless industry as they provide valuable insights and methodologies for advancing challenging projects. No-Dig Down Under 2025 SNOWY 2.0 – MARICA ROAD WEST HDD: ENGINEERING INNOVATION IN EXTREME TERRAIN Rowena Stockton and Bryce Morrow 1

Techniques