Dixon Street pump station and rising main- a first for New Zealand

GHD was engaged by Wellington Water to carry out the investigation, design, tender and contract supervision for a new wastewater pump station and associated pipework, under Victoria and Dixon Streets in Central Wellington.

The Dixon Street Pump Station project is the first to be constructed in Central Wellington in over 40 years. This allows Wellington Water to provide wastewater services to a growing population, and relieves pressure on other pump stations around the city, reducing the chance of overflows into the harbour.

Given the lack of space, the central location presented a significant challenge, requiring an innovative approach that would work within the space constraints, while still delivering all the services required.

Alongside Brian Perry Civil, we’ve designed and supervised construction on the new pump station using the innovative segmental caisson method.

Using pre-cast concrete segments shipped in from the UK, this system starts construction at ground level, and works downwards, and is faster, quieter, and safer than traditional construction methods. Concrete segments were assembled on-site to form rings, which were then pushed below ground level, to form the wall of the 8-meter-deep shaft.

Given how close the construction site was to buildings, roads, and trees, it was important to create as little disruption as possible for those living, working and commuting nearby. Segmental caisson construction has proven perfect for this site, as it requires a significantly smaller site footprint than many traditional methods.This project has won the IPWEA New Zealand Excellence Award 2019, for the best public works project (under $5M).