Corban Reserve Stormwater Upgrade – Stage 1

Alta provided specialist services and advice at all project stages of this stormwater upgrade, from planning to delivery. Rory Bishop served as Engineer to Contract, while Craig Scott managed Engineer’s Representative duties during the tender stage.

Project scope

The Corban Reserve Stormwater upgrade was a complex, multi-faceted project that was organised into stages.

The project involved the construction of a new 713-meter-long, 2100mm diameter stormwater pipeline using a micro tunnel boring machine (MTBM). This pipeline is designed to divert stormwater flows away from the closed landfill beneath Corban Reserve, significantly reducing the risk of leachate contamination and gas accumulation. In addition, a 240-meter-long, 450mm diameter low flow pipeline was installed using horizontal directional drilling to maintain base flows in the lower Waitaro Stream, thereby supporting the stream’s ecological integrity.

Several stream restoration efforts were also completed. The upper Waitaro Stream, previously confined to a concrete-lined channel, was naturalised to a more natural stream profile with riparian planting, enhancing habitat quality and overall stream health. In Murillo Reserve, a section of the mid-Waitaro Stream that had been piped underground was daylighted, uncovered and restored to an open stream improving ecological connectivity and offering aesthetic and recreational value through landscaping upgrades. To support pedestrian access and connectivity, three new footbridges were constructed at Border Road Esplanade, Murillo Reserve, and between Imperial Place and Spode Place.

Alta’s work

The Alta team supplied constructability input through early planning stages, and cost estimation and contract development advice through the tender stage.

Our team took on project management responsibilities during the delivery stage as Engineer to Contract and Engineer’s Representative.

‍Key learnings

The Alta team developed a deeper understanding of mining regulations, and implementing stream works methods as part of the resource consent. We ensured the work met fish passage requirements.

Alta’s project team

Rory Bishop (project lead/Engineer to Contract), Craig Scott (Engineer’s Representative), Cameron Stewart (constructability).