357A Karori Rd renewals



Wellington Water




September 2023


Mobile Plant Fleet,Underground Services,Traffic Management,Connections,Pipe ramming,Pit drilling

Customer type:

Government & Local Government


Renew approximately 80m of 400OD PE100 SDR17 & 160OD PE100 SDR17 Stormwater & Wastewater drainage through back sections in Karori. Trenchless installations underneath an existing structure and a protected tree. Stakeholder management and reinstatement in accordance with residents’ agreements.

This was a tricky project involving renewing wastewater and stormwater mains through the back of private properties, as well as under existing structures and a protected tree.

We worked closely with Egis during an ECI phase to determine the correct installation technique for each section of pipe. A variety of trenchless techniques, including pipe ramming and pit drilling were used to successfully install the network. All of the work was carried out in private property with significant disruption to the residents. The team on site followed through on the work during the planning stages of the project to make sure we kept all of the residents positive and ensure that the project was handed over smoothly.


To address working in private properties, we built on work with Egis to maintain and develop positive relationships with the residents. The team on site behaved respectfully throughout the project. Open communication and a quality finish meant that the project was handed over successfully upon completion.

To install the stormwater main under an existing structure with insufficient set back to use a Horizontal, Directional Drill rig, we used pipe rammed a casing to sleeve this pipe. The ram encountered rock and a buried tree stump that hampered progress but with some determination the team successfully completed this element of the project.

Installing the wastewater main under an existing structure, we used a pit drill to install it parallel to the stormwater casing. The pit drill was able to be positioned on grade and alignment of the pipe so that the set back requirement was eliminated. A smart technique for this type of application. We used the pit drill again to install a large diameter stormwater main under an existing protected tree's root ball. The drill had no trouble installing a larger pipe diameter over this short distance.