Wairau Road Substation Hero

Wairau Road Substation

The North Auckland urban area is growing rapidly. Since the Auckland Harbour Bridge opened in 1959, the North Shore alone has expanded nearly five-fold, from a population of 50,000 in the late 1950s to 229,000 in June 2011. The after diversity maximum demand (ADMD) for electricity in the North Auckland and Northland region is forecast to grow from 908 megawatts in 2012 to 1254 megawatts by 2027. This is an average annual growth rate of 2.2 percent, which is higher than the national average of 1.7 percent per annum. To meet this demand, and to provide greater reliability of power supply The North Auckland and Northland (NAaN) grid upgrade project was born.

The Wairau Road Substation is one of two new substations that form part of the NAaN project. This project reinforces transmission into the Auckland Region and across the harbour to North Auckland and the Northland Region.

It adds new 220 kV transmission capacity to the National Grid by providing 37 km of underground cable from Pakuranga to Albany through a series of existing and new substations, and a cable across the Auckland Harbour Bridge. 

Transpower’s aim:

  • To reduce Auckland’s reliance on the single transmission line between Otahuhu and Henderson by providing an alternative route to move power through and around Auckland, providing greater reliability of power supply to the Auckland and Northland regions.

What we did:

The detailed brief asked for a building that was architecturally pleasing as well as functional. The twelve metre high substation was built on multiple levels to conserve space and contains a large basement, making it more compact than a traditional outdoor site.

The compact station design includes a gas insulated switchgear (GIS) room which houses electrical disconnect switches and fuses or circuit breakers that control, protect and isolate electrical equipment. This GIS room has replaced the preexisting outside 33kv switchyard.

The project was completed in four phases which allowed the client early occupation in critical areas and enabled them to commence specialist fit out works. We were able to complete each stage on time by adhering to program restraints and tight deadlines.

Safety is always of the highest importance on our projects and we paid particular attention to the fact we were working in a live substation environment with confined spaces. Because the site was on an existing substation, we had to adhere to specific requirements from the client with regards to personnel protective equipment and electricity procedures.

Unique challenges:

  • The station is built on an existing substation in a confined location. As a result traffic had to be managed via a traffic management plan and compliance with local restrictions.
  • An open stormwater channel sits adjacent to the site and its location had to be planned into the position on site.  The team managed this and installed a successful groundwater control system by using storage tanks and filtering methods to pump clean water from the site into the open stormwater channel.
  • The tight location and HV overhead lines meant that an innovative solution was required in order to erect large PC panels. This was achieved through hours of planning and with the help of cranes that manoeuvred around the overhead lines.

The outcome:

The NAaN project, the latest addition to the National Grid, was put into full commercial operation on 26 February 2014. The whole project, which was completed under budget, provides an alternative route to move power through and around Auckland. This has resulted in a greater reliability of power supply to the Auckland and Northland regions. 

Projects of this size in urban areas require co-operation from many parties, and we worked closely with NZTA and Auckland Transport to create as little disruption to people as possible. I’d like to thank those parties that assisted us and also those people living and commuting close to our cable route for their patience while we built this important piece of New Zealand infrastructure.

Alison Andrew

Transpower Chief Executive