Otago Harbour Crossing Line Upgrade

Project detail

This project saw the installation of two new 11kV submarine cables (including a replacement for the existing Port Chalmers 3 submarine cable which was installed in 1947), as well as the one low voltage cable to customers on Quarantine Island from Portobello.  

This part of the network supplies power to the northern end of the Otago Peninsula, and the upgrade is necessary to maintain a reliable power supply to over 700 customers on the Peninsula, including the customers on Quarantine Island Kamau Taurua.

As well as replacing ageing assets, this project addressed public safety risks associated with end of life assets, improved the view along the pristine stretch of coastline, and ensures the current power reliability to the Portobello community.

What are the benefits of the project?

This project has significantly increased the supply of electricity to the Portobello community and the wider Peninsula – currently 728 existing customers and growing. It also has wider benefits for shipping, tourism, and wildlife. The overhead lines were a barrier to some vessels entering Dunedin’s upper harbour, and the lines and towers will also no longer be a hazard for sea birds.

Preparation and planning

Planning and design work began in December 2020 and through to April 2021 when site preparation was undertaken on both sides of the harbour. Prior to work commencing, we undertook an Iwi blessing on site, this involved the turning of the ground to initiate the construction works.  We also completed an underwater survey of the submarine cable route and worked closely with submarine cable specialist SeaWorks, to develop the installation methodology.

Breaking ground

The team at Aurora Energy were proud to mark the official start of the Otago Harbour Crossing line upgrade with a traditional blessing of the planned submarine cable route. We were joined by members of Ōtākou Rūnaka, Unison Contracting, and Clearwater Contracting and were honoured to have Te Atarau Cassidy break ground for us at Quarantine Point, Portobello. We were lucky to have such a beautiful day to mark the start of this exciting project. Thank you to everyone who attended! 

Installing submarine cables - May-June 2021

The new submarine cables were laid on the harbour floor by the Seaworks team on the Patiki Barge (custom fitted and transported South from Picton especially for this project) and Unison in May/ June. The two cables between Port Chalmers and Portobello each carry 300-350 amps, compared with 150 amps for an existing, older submarine cable. A third, smaller submarine cable has also been laid between Quarantine Island Kamau Taurua and Portobello.   

Removing old lines and towers - September 2021

In September, the lines and six towers came down. The first of the towers was removed from Clive Matthewson’s garden in Port Chalmers. He enjoyed a ceremonial afternoon tea (thank you for the cheese rolls!) to bid the pylon farewell with the ElectroNet team and to celebrate his much-improved view. Over the next two weeks the other towers on Quarantine Island Kamau Taurua, Goat Island Rakiriri and in Portobello, were removed in pieces by helicopter by HeliOtago. We also used the helicopter to deliver a new water tank and gravel to make paths for the Kamau Taurua community. 

Restoring Quarantine Island Kamau Taurua to its natural beauty - September 2021

The Aurora Energy team joined with the Quarantine Island Kamau Taurua (QIKT) Community, Save The Otago Peninsula (STOP) Incorporated Society, and volunteers from the Otago Peninsula Trust and Otago Polytechnic to plant natives on Quarantine Island (Kamau Taurua). We donated 1000 plants to the QIKT community, helped to transport these over to the Island, and planted 300-400 natives. The QIKT community and visiting groups will continue to plant the remaining number over the coming months and years.

A very big thank you to all of our volunteers for giving their time. It was a great chance to come together as a community to help restore the area to its natural beauty following the removal of the pylons as part of the Otago Harbour Crossing Project last year. A real team effort!

Thanks to all involved!

The project went from conception to commissioning in one year. A big thank you to the contractors, stakeholders and community who made this possible. It is a major project for the community, who will see benefits for years to come. We will work with community groups to replant the areas with native plants and restore the natural beauty where the towers were removed from. 

Otago Harbour Crossing Project Videos

Our video series takes you behind the scenes on the Otago Harbour Crossing project at each of its major phases, including the seabed survey, consultation with the Harbour community, the installation of three submarine power cables across the Harbour floor, and the removal of the six lattice towers and lines that crossed the Harbour from Port Chalmers to Portobello. We’ve also taken some amazing video footage, including by drone, as the ElectroNet crew, in conjunction with HeliOtago, removed the lattice towers. Check it out below!

Otago Harbour Crossing Project – Part One: Seabed Survey

Otago Harbour Crossing Project – Part Two: Community Impact, Quarantine Island Kamau Taurua, and Local Otakou Runaka

Otago Harbour Crossing Project – Part Three: Submarine Cable Installation

Otago Harbour Crossing Project – Part Four: Removal of the Power Lines Crossing Otago Harbour

Crews scale de-energised lattice tower on Goat Island

Farewell to 1950s Tower

Removal of the Portobello tower

Kamau Taurua Quarantine Island Tower Removal

Any questions?

For more information, please contact us.