We're installing new underground power cable along Brougham Street

Brougham Street daily update – 07 - 10 December 2023 Traffic management will be in place every night starting from 6pm until 6am the next day, with one lane available in each direction on Brougham Street. Currently, we're working around the intersection of Wilsons Road and Brougham Street. The works involve digging the trench, installing the cable ducts and filling the trench. We're planning to finish these works in mid-December. A big thank you to nearby residents for their patience while we work at night.

Click here for the latest work notice

A secure and resilient power network is essential, so we're strengthening our electricity network

Our work on SH76 Brougham Street

As part of our project to install a new 66kV power cable from Bromley Substation to Milton Substation, we're currently working at night on Brougham Street. Initially, we’re working near the intersection of Opawa Road before moving towards Ensors Road. Later, our work area will move west towards Waltham Road and Burlington Street. We'll be working at night between 6pm and 6am. Brougham Street will remain open while we work with some restricted turn movements. Please check the latest work notice for details.

Bromley to Milton project background

Some of our underground cables in Christchurch City are 40-60 years old. These older cables are still working, and will continue to do so under normal conditions. However, they are vulnerable to earthquakes and should we have another large earthquake, there is the potential for faults on these cables. Given the age of the cables they are difficult to repair, and after a significant shake these cables could take some time to fix.

Replacing these cables to strengthen our network is a major programme of work for Orion. One of the first projects is installing a new underground cable from Bromley Substation to Milton Substation. This new power cable is the first of 12 new cables that will create new ring circuits in Christchurch City. These ring circuits have two purposes:

• They allow us to shift power around the network. This means that if there is a fault on the network we can re-route the power to keep customers on.
• Once the new cables and circuits are in place we can progressively retire the old cables as the power will be supplied via the new circuits.

The new cable uses the latest cable technology and is sized to accommodate future growth.

Where are we working, and when?

We’re installing a new underground 66kV power cable from Bromley Substation to Milton Substation. The new cable is installed in the road.

We started construction on the new power cable in November 2022. It will take us about 15 months to install the cable along the 7.5km route from Bromley to Milton Street. The cable will be laid in nine stages or work areas - see map below.

What does our work involve?

The new 66kV cable will be installed in a trench in the road. On Brougham Street, we’ll be digging a trench in the road and then installing cable ducts. Ducts are plastic pipes that we thread the cable through later.

After we have installed ducts, we reinstate the road surface and traffic management is removed. Ducting allows us to speed up the cable laying process and reduce impacts on traffic.

We’re also building a new switching station at our Milton Substation. The new cable will feed into the switching station. It gives us the ability to switch between power circuits meaning that we have alternatives in the event of an outage and can restore power more quickly. See more details below.

How do you install the cable?

Stage 1 - Traffic management set up We need to have traffic management in place to safely install power cable into the road. This includes fencing the work site and temporarily changing traffic flows.	Stage 2 - Removal of the road surface The first step of the construction process involves breaking up the road surface. A milling machine is used to remove the paved layers of the road.	Stage 3 - Excavation of the trench Next, we dig a trench to install cable ducts into. Hydro-excavation is used where pressurised water breaks up the soil, which is then vacuumed up.
Stage 4 - Laying the cable To install the new cable, we first place three cable ducts in the road. The ducts are plastic pipes that we thread the cable through later.	Stage 5 - Filling in the trench The trench is backfilled using fine crushed rock. A compactor machine is then used to compress the contents of the trench and fill in air pockets.	Stage 6 - Road surface repair Once all the ducts are laid and the trench is backfilled, the road’s surface - or paving - is repaired.
Stage 7 - Removal of the traffic management After the road has been reinstated, temporary traffic management is removed. Remaining loose chips are swept away within a week or so, and road marking is reinstated soon after.	Stage 8 - Cable pull Three cables are installed into the ducts in each trench. They are carefully winched along the trench, from one joint bay to the next. Pulling the cable is difficult as it is heavy and not very flexible, and we want to avoid damaging it.	Stage 9 - Cable jointing We install sections of cable in 600-800m lengths, and join the sections together at joint bays. Once the cables are joined together, we then fill in the joint bays and repair the road surface in this area.
Milton Switching Station The power cable will connect into a new switching station at the Milton Substation on Milton Street in Sydenham. A switching station allows us to switch between power circuits meaning that we have alternatives in an outage and can restore power quicker. It will be housed in a purpose-built, secure building next to Faraday Street. Construction is currently underway.	This is how the new switching station could look.

How will this work affect me?

This is a construction project so homes, businesses, and community facilities along the cable route will be impacted while we install the ducts and cable in the road. Road users will also be affected by the traffic management in place.

Overall traffic management

We're laying the new 66kV cables in the road and there will be traffic management in place to enable us to do our work safely. The traffic management set up will change as move along the cable route, and could include:

There will be no on-street parking available around Brougham Street where we are working.

Power supply

There will be no disruption to the power supply to install the new cables. However, along some parts of the cable route we may need to relocate some existing underground power cables. To do this work safely there may be power outages for some customers. You will be notified of any power outages by your power retailer.

Access to properties or businesses should not be affected when we are working on Brougham Street. We are only working at night, and the outside lanes of Brougham Street will remain open during this time.

Rubbish collection

Your rubbish will be collected as normal. If we are working outside your property, please place your rubbish bins out to the kerb as normal. The crew will move the bins for collection if necessary and return them to outside your property.

The story of Ōpāwaho

On the outside of the new switching station building we have worked with a local Ngāi Tāhu artist who has designed a special art piece for the outside of the building. This tells the story of the natural environment of Ōpāwaho/Heathcote River which was an important mahinga kai area, or source of plentiful food, particularly tuna (eels), pātiki (founder), and inaka (whitebait). Ōpāwaho was also an important travel route connecting peninsular settlements with Ōtakaro and north to Kaiapoi. Click here for more information on the design. The artwork on the new building draws inspiration from the tukutuku – a geometric pattern that acknowledges the importance of mahinga kai and the links to the Port Hills and the rivers. We're also planting native trees and shrubs around the switching station, to enhance biodiversity, and provide food for birds and insects. It’s really exciting to be working with mana whenua to share their stories through our infrastructure. You will be able to view the art from Faraday Street once the switching station is complete.

What are the benefits of this project?

These works are essential to powering a cleaner and brighter future with our community. Installing the new power cable and switching station will strengthen the resilience and security of the power network and provide for the future growth of our city.

The network will be stronger in a major earthquake and we'll be able to restore power quicker.		The new cable will be another circuit supplying Christchurch. If there is a fault on the network we will be able to keep more customers on and restore power quicker.		The new cable is sized to cater for our growing demand for power.