GSI PROJECTS
Ruamahunga
Overview:
As part of Cyclone Gabrielle recovery efforts, GSI, in partnership with Andy O’Sullivan engineers, was contracted by NZTA for a design-and-build project to repair an overslip at Ruamahunga. The slip had been active for years, posing a threat to property above the slip and disruption and dangers to road users along State Highway 25.
- Client:NZTA Waka Kotahi
- Designer:Andy O'Sullivan for GSI
- Scope:Dimensioned soil nail system with Geobrugg G65/s TECCO mesh
- Project Start/Completion: Nov 2023 - Jul 2024
Design.
The initial plan for this project included the use of helicopters to lift specialised plant, equipment, and materials to the top of the site. However, once the team were on site, they identified additional problem areas that required further careful planning to avoid delays. We worked closely with the Department of Conservation, NZTA and local homeowners to expedite the approvals, safety and access.
Build.
The crew manually removed approximately 750m³ of slip debris and used two lightweight wagon drill rigs to install 492 soil nails, each 7-10 meters deep, across three separate areas simultaneously. To prevent erosion and rockfall, the team applied biocoir coconut matting and Geobrugg Tecco g65/3 mesh. A tensioned cable system was also installed to secure the repair.
Deliver.
Upon completion, all access tracks and site compounds were removed, leaving minimal trace of the work. The team were commended on their workmanship, organisation, and approachability by the clients, engineers to the contract, and the homeowners directly affected by the work that was being undertaken on the project.
