The Cliffs Retaining Wall
Our client’s house sits at the top of a 30m high sea bluff above the State Highway in Nelson. The property features terraced retaining walls parallel to the cliff edge. The severe weather event in August 2022 caused a landslip on the cliff face which progressed across the property boundary. A section of the outer retaining wall along the cliff’s edge failed, causing damage to the second and third tier timber pole walls located behind. Eliot Sinclair were engaged to reinstate the slope and design the remedial retaining wall.
Client
Private ClientServices
- Geotechnical Engineering
- Structural Engineering
The challenge
A range of slope hazards and land instability issues associated with the bluff site created unique challenges with this project. The State Highway runs beneath the cliff and would be impacted by any falling debris triggered by further landslips. The site had restricted access and a steep slope close to the working boundary. Any machinery required to work on the site needed to be craned over the house from the road above. These factors need to be taken into consideration and added complexity to the design works.
The solution
We provided our client detailed retaining structure designs that included 2D design models, from which we determined construction requirements and completed a slope stability assessment. Our geotechnical engineering experts designed an anchored steel retaining wall and specified construction methods that would mitigate land damage on the site.
During the construction phase we provided professional construction monitoring services for the retaining wall. As site access and manoeuvrability were heavily restricted due to operating in an unstable area, we worked closely with the client and specialist contractor to solve any issues that arose in a time critical manner. We strove to answer all contractor questions and work through any issues on the same day, facilitating a speedy process. Our fast communication resulted in time and financial savings for the client and lower risk of jeopardising the slip hazard during the construction.
