After a landslide displaced the piers of a live 900 mm wastewater pipeline, we took Watercare from emergency temporary supports through to a deep-piled permanent foundation.
- Client
- Watercare
- Services
- Structural engineering, temporary works, construction support
- Location
- Akoranga Reserve, Northcote, Auckland
- Scale
- 900 mm pipeline · 5 × 1,800 mm piles · 30 m deep · 17 m ground beam
- Status
- Complete 2026
01 / Project overview
The brief
Following significant storm events, a major landslide occurred within Akoranga Reserve, displacing the supporting piers of a 900 mm diameter wastewater pipeline owned by Watercare. One pier had moved so far that an immediate engineering response was needed to protect the pipeline and the public reserve around it.
We supported Watercare through the full engineering journey: assessing the failed supports, designing emergency temporary works, and then designing a permanent replacement foundation able to hold the pipeline securely in challenging ground.
What made this project demanding was the combination of constraints. We weren't designing on a clean site. The solution had to respond to a failed existing asset, unstable ground and a live wastewater pipeline, while managing a safe transition from emergency works to a robust permanent solution.
02 / Our approach
How we delivered it
Emergency assessment and temporary works
We carried out a structural assessment of the displaced and damaged supports, then designed emergency temporary supports to stabilise the pipeline. We also designed a stormwater diversion to manage water across the slip area while the permanent solution was developed.
Safe deconstruction methodology
With the pipeline still a critical part of the network, we developed the detailed methodology for Pipeline & Civil to safely deconstruct the existing pipework, sequencing the work so the asset stayed supported at every stage.
Deep foundation system
The permanent solution needed to reach competent ground well below the slip. We designed five 1,800 mm diameter reinforced concrete piles extending approximately 30 m deep, tied together by a reinforced concrete ground beam spanning approximately 17 m. A reinforced concrete column and capping beam sit on this foundation, replacing the damaged pier and supporting the suspended pipeline. Geotechnical input was provided by Baseline Geotechnics.
Construction support
We provided construction support and inspections throughout delivery, working closely with Watercare, Pipeline & Civil and Baseline Geotechnics to bring the design through to completion.
03 / The outcome
“ A critical wastewater pipeline that was left hanging by a landslide now sits on a deep-piled foundation designed for the ground it’s in. The project was recognised at the 2026 CCNZ National Civil Construction Awards.”
04 / Gallery
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