9 October 2024
Building resilience in our network
In late 2022 we discovered that transmission Tower 29 on the Western Hills in Whangārei was at imminent risk of collapsing. Located adjacent to Clement’s Quarry, unprecedented heavy rains had started to erode the terrain around the tower’s foundations. Tower 29 carried the only 110kV lines to the Whangārei city area.
High priority was given to identify and construct an alternative supply route to the region before a long-term solution, Tower 29A, could be constructed on stable land.
The temporary solution
To mitigate the risk of potential land slippage, two temporary transmission towers were created as a bypass – one East, one West of Tower 29. In case one temporary tower were to fall, the other would still provide electricity supply to Whangārei. Time was of the essence – the bypass line was constructed using distribution poles, as transmission poles would take six months to source.
Our network team provided the technical expertise in collaboration with Edison Consulting Group to project manage, and engineering design experts Lumen.
Read more on this portion of the project here
The permanent solution – constructing Tower 29A
The two-year lifespan of the temporary towers required the design and construction of a new permanent line, including sourcing a new 40m monopole to support a new 110kV conductor. A suitable site for Tower 29A was selected in the forest area adjacent to Clements Quarry, known to Te Parawhau as Pukenui Ngahere.
As kaitiaki, Te Parawhau were instrumental in shaping the construction process and the design of the tower itself. Read more about their contributions to this project here.
Construction works commenced in April 2024 and was completed over a four-month construction period by Northpower’s Hamilton based transmission crews.
In July 2024, the staged transfer of a conductor to the new section of the 110kV transmission line was completed.
Great outcomes
The successful delivery of the project ahead of schedule is a testament to the way our engineers tackle problems that arise and highlighted the benefits of quality collaborations with hapū, local councils and external consultants.
Our Whangārei customers now have an electricity supply with improved resilience. This project was recognised at the Electricity Engineers’ Association of New Zealand awards this month, winning the Engineering Excellence Award. Engineering and Operations General Manager Raj Singh accepted the award on behalf of the project team, joined on stage by Chief Operating Officer Contracting Josie Boyd and Project Delivery Manager Colin Boggiss from Edison Consulting Group. Te Parawhau were acknowledged for their guidance throughout the project.