GSI PROJECTS
Epitaph Haast
Overview:
The Epitaph Landslide had posed persistent threats to a coastal segment of State Highway 6 for several decades. In response, NZTA and Fulton Hogan appointed GSI to undertake a long-term, specialist slope stabilisation project. The initiative presented numerous challenges, including complex staging requirements, a remote location, poorly bedded sandstone and exposure to adverse weather conditions.
- Delivery Partner:Waka Kotahi, New Zealand Transport Agency
- Designer:GSI
- Scope: Tailored capping beam and micropile drilling.
- Project Start/Completion: March – June 2025
- Location: Haast, West Coast
Design.
Our design solution featured a 115 m reinforced concrete capping beam under the seaward lane, supported by 280 micropiles, across three zones to match the variable ground conditions. Additional measures included a dewatering system, real-time monitoring of slope movement and a temporary rockfall barrier.
Build.
Two teams worked in parallel; one carrying out the micropile drilling while the other followed behind with civil and structural works. We adapted our build methods to overcome the site’s spatial and geological challenges. Throughout the project we had a seamless interface with our other contractors delivering upslope risk mitigation and traffic control measures.
Deliver.
The integrated beam and micropile system provides additional stability of this critical route. Through engineered design, real-time monitoring, and flexible construction sequencing, the system addresses immediate geotechnical risks while allowing for future design development if required.