Victorian electricity distributor CitiPower has begun the first phase of a major upgrade to future-proof Melbourne’s underground power network. Energy Source & Distribution takes a look at the underground tunnels and what they reveal about the city’s past.
The network
CitiPower moves electricity to and from more than 349,000 homes, businesses and essential services across Melbourne’s Central Business District (CBD) and inner suburbs.
The network also supports a diversity of commercial and industrial customers, ranging from cafes and small businesses to restaurants and major office buildings as well as world-class sporting precincts, public health, education, government and cultural facilities.
The network is made up of more than 4,500km of wires and cables—enough to stretch from Perth to Singapore—and more than 57,500 poles and associated infrastructure. It’s operated and maintained by a team of highly-skilled tradespeople and professionals, committed to providing reliable power to homes and business.
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CitiPower services are delivered from a depot in Richmond as well as from a customer contact centre in Bendigo and corporate office in Melbourne.
The network in Melbourne CBD, as with the rest of CitiPower, has an extensive annual maintenance and upgrade program dedicated to ensuring ongoing reliability and safety of the network.
Specifically for the CBD, CitiPower completed works in 2021 to upgrade supply capacity to the northern and eastern CBD, through development of the new Waratah Place zone substation. The works proposed at CitiPower’s Little Queen (LQ) zone substation will provide the same increase in capacity to meet the growing demand across the central and southern CBD for decades to come.
CitiPower head of network planning Andrew Dinning said demand for electricity in the CBD was already high and continually growing.
“Currently, the peak demand for the CBD network is around 500MW,” Dinning said.
“To set that in context, that’s the same as one generating unit at somewhere like the Loy Yang power station, but dedicated to supplying less than three square kilometres of CBD.”
It’s currently expected that demand in the Melbourne CBD will increase by at least 60% over the next 10 years.
Scope of the upgrade
This project is a major $24 million upgrade of the city’s power network to help future-proof it against growing demand. The tunnel upgrade is about developing the tunnel beneath Little Queen Street to make sure it remains a safe and reliable conduit for current and assets.
This work is a precursor to a larger three-year revamp of the nearby LQ zone substation, which will provide greater capacity and flexibility to support both planned new developments in the city and greater electrification of existing customers across the CBD.
The size of CitiPower’s team varies according to what stage of the work is being completed at any one time, but generally consists of 40-45 people. The team is made up of network planners, asset managers and analysts in the early stages, to define the best option to progress with.
Once the preferred solution is defined the project team changes to include project and design managers, civil/geotechnical engineers, electrical design engineers, civil contractors and specialists in equipment installation, along with fitters, testers and cable jointers.
Working in the tunnels
CitiPower works to minimise impacts to customers wherever possible and actively avoids unnecessarily impacting customers. Before upgrading any of its assets, CitiPower will move customers supplied from that asset onto other areas of the network to ensure minimal interruption.
CitiPower has access to a range of tunnels under the Melbourne CBD. Some of these are over 100 years old. The tunnel under Little Queen Street was first built in the 1930s and stretches for 80m.
Interestingly, a tunnel was unearthed during redevelopment of the Southern Cross station nearly 20 years ago that CitiPower repurposed to carry some of its underground cables.
Over the years, these tunnel excavations have yielded some interesting finds that provide a glimpse into Melbourne’s past.
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“We found a thick road surface under Todd Road in Port Melbourne a few years ago,” a CitiPower spokesperson said.
“Through some research, the team discovered it was the old runway from World War II, where they built aircraft at Fishermans Bend then rolled them out on the runway and flew them to New Guinea.
“Another interesting find was an old cable car system in Lonsdale Street, including the culverts and a gear room that was just buried and abandoned in the city.”
Upgrade schedule
CitiPower expects to complete the tunnel upgrade by October before it begins the electrical upgrade work later this year.
“We expect the major upgrade work at the LQ substation to take up to four years and will include a 12-month design period, before construction and commissioning begin,’’ a spokesperson said.
