Upgrades that are currently being made to the Kaitoke and Whakawhirinaki – Silverstream pipe bridges are crucial for the long‑term stability of Wellington’s water infrastructure, and are set to ensure enhanced resilience, safety, and reliability for the future.
Water infrastructure is front of mind for New Zealanders right now. The dissolution of the Three Waters/Water Services Reform Programme, the ongoing issues with drinking water quality due to recent natural disasters and storms, and the issues surrounding funding have brought water reform to the fore. In fact, 82 per cent of Kiwis feel that it’s extremely important to improve the quality of water in Aotearoa1.
Wellington Water and Greater Wellington Regional Council’s Kaitoke and Whakawhirinaki – Silverstream pipe bridges, delivered by main contractor Brian Perry Civil, aren’t just a solution to ensuring reliable water for Wellington’s residents; they’re also a feat of seismic resilience and flood protection, and of operational flexibility and increased capacity that takes into account community usage and environmental impacts. While water has been flowing through the new pipe carried by the Kaitoke Bridge for some time, the Whakawhirinaki – Silverstream Pipe Bridge is set to open in 2025. The bridges and adjoining pipeline are a step in the right direction, aiming to futureproof Wellington’s water supply for generations to come.
The Kaitoke Pipe Bridge: a pillar of Wellington’s water supply
The old Kaitoke Pipe Bridge played a crucial role in the region’s water supply, delivering 50 per cent of the raw water to Wellington’s bulk water network; however, this aging piece of infrastructure was inadequate for current seismic standards, and has been plagued by leaks due to cracks. The old bridge was replaced with a more resilient network arch bridge designed to support the new water pipeline, which also facilitates access for maintenance and recreational use.
Water sourced from the Te Awa Kairangi/Hutt River is treated at the Te Mārua Water Treatment Plant, and from there, it is distributed through a main pipeline to Upper Hutt, Stokes Valley, Porirua, and up to 40 per cent of Wellington City. This critical pipeline carries approximately 60 million litres of water every single day, highlighting the vital role it plays in the daily lives of residents. The urgency of these upgrades is magnified by the potential risks posed by seismic and flooding events, which could severely disrupt water supply.
The Silverstream Pipe Bridge Programme is part of a broader $200-million infrastructure investment initiative aimed at enhancing Wellington’s bulk water supply system. This plan includes significant upgrades to existing pipelines and systems, as well as essential work to improve the capacity of the Te Mārua Water Treatment Plant.
The vision behind the Whakawhirinaki – Silverstream Pipe Bridge
Alongside the Kaitoke upgrades, the Whakawhirinaki – Silverstream Pipe Bridge is being constructed to replace the existing pipeline crossing over the Te Awa Kairangi/Hutt River, which has been identified as vulnerable to seismic and flood events. The name, gifted by local iwi, signifies trust and responsibility in managing the region’s essential water supply.
The ambitious design features a three-span bridge, which includes a striking 100-metre network arch alongside robust steel trusses. Plans call for the installation of 1000 meters of new steel piping, which will enhance the resilience of water delivery against seismic disruptions and flood risks. Brian Perry Civil is leading this construction effort, using innovative design principles to minimise weight and carbon emissions.
‘Brian Perry Civil has been involved in the Silverstream Pipe Bridge project since 2020,’ says Hayden Chapman, Brian Perry Civil’s Project Manager. ‘Originally a construct‑only contract, Brian Perry Civil partnered with Holmes Consulting, Eastbridge, and E Carsons to challenge the client’s design. This led to a more slender solution being developed by our team, ultimately costing Wellington Water less and significantly reducing the project’s carbon footprint.
‘The project has progressed well, and we recently celebrated the milestone of getting the main 100-metre network arch span placed across Te Awa Kairangi/Hutt River. Work will continue into the first half of 2025 installing the new pipeline across the bridge, creating a new resilient section of bulk water pipeline for the Wellington Region.’
‘I’m really excited to see the safe installation of the Whakawhirinaki bridge, a significant project milestone that has only happened through the skill, dedication, and commitment of Brian Perry Civil’s design and project teams to ensure the overall project will be delivered on program,’ says Gareth Penhale, Project Director at Wellington Water.
Emphasising community and environmental stewardship
Both bridge projects extend beyond infrastructural upgrades; they seek to enhance community connectivity and environmental stewardship. The design for Whakawhirinaki includes dedicated paths for walking and cycling, promoting recreational use while ensuring the operational maintenance of the water infrastructure.
Environmental considerations play a pivotal role in the project’s design and execution. Wellington Water has collaborated with Forest & Bird and the Department of Conservation to ensure that construction practices align with ecological preservation efforts. The integration of riparian planting along the riverbank is a crucial aspect of minimising environmental impact and supporting local wildlife.
Ensuring future resilience: a collaborative effort
As Wellington grapples with the realities of climate change and the potential for natural disasters, both the Kaitoke and Whakawhirinaki – Silverstream pipe bridges are essential investments in the future of the region’s water supply. These projects exemplify Wellington Water’s unwavering commitment to delivering reliable, environmentally responsible infrastructure solutions that meet the needs of the community.
The collaborative approach taken by Wellington Water and its contractors has fostered an environment of shared responsibility and innovation. The partnerships formed throughout the planning and construction phases have enhanced the ability to adapt to evolving project requirements, while also ensuring that the highest standards of health and safety are maintained.
The Kaitoke Pipe Bridge is now complete, and the Whakawhirinaki – Silverstream Pipe Bridge is scheduled for completion in 2025. These projects signal a brighter future for Wellington’s water infrastructure, and embody a commitment to resilience, safety, and sustainability, reinforcing the vital role that well-planned infrastructure plays in safeguarding the health and wellbeing of communities.