The Molonglo Valley’s housing subdivisions in Australia’s capital are undergoing key transmission work, requiring the relocation of 1,500 tonnes or 58km of 132kV cables underground and the removal of above ground transmission towers.Works such as these have many moving parts, requiring transparent, upfront communication and a unified plan with all contractors to ensure works keep moving and are completed safely. Zinfra was awarded tender for the project and has been on the ground in Canberra, working on relocating Evoenergy’s Molonglo transmission assets since 2022.
The Molonglo 132kV Relocation Project is part of the ACT Government’s Suburban Land Agency work on subdividing the region for future homeowners. Zinfra brought its expertise to Molonglo, where the team worked alongside principal civil contractors to overcome significant safety and workplace challenges. The project brought together two of Zinfra’s key business units, the Projects and Infrastructure Business Unit led by Site Manager, Dan Coleman, and the Power Services Unit led by Construction Manager, Gary Kiri.
Perseverance from the beginning
The first challenge of the project was early COVID-19 restrictions, which meant early planning and preparations had to be conducted remotely, without any physical visits to the site locations. Alongside these delays, La Nina wet weather systems continued to pose challenges to the Zinfra team on the ground. Although this impacted site visits associated with scoping and quoting, it didn’t impact the overall delivery of the work.
Undeterred by the obstacles, Mr Kiri said Zinfra and his team were resilient and persistent in getting on with the job.
“We adapt to the situation, we overcome it, and we keep moving forward. If there’s a solution out there, we’ll find it. That’s the sort of people we are,” Mr Kiri said.
Supported by his team, Mr Kiri said each of his team members had a reliable and important skill set pivotal to solving the ongoing obstacles.
“The team that we have – they’ve been brilliant from the start. With all the challenges that we had, a lot of other crews would’ve just packed their bags and started walking down the road. But our team has been 100 per cent on board, and they have been coming up with solutions,” Mr Kiri said.
Confidence in the complex
With a focus on safety and teamwork in mind, the Zinfra teams were able to manage an increasingly complex construction site. Not only were Zinfra working alongside and in large concrete pits to install new cable conduits, they had to liaise with the civil contractors on site. This also involved managing large levels of construction equipment, such as large cranes, excavators, and trucks which often travelled across the main access road.
Zinfra’s trusted support and guidance was pivotal to the entire Molonglo transmission project. Mr Coleman said the project required transparent and upfront communication between all parties to ensure that all work could continue in a safe and secure manner. This meant managing access roads, equipment and keeping sites as physically separated as possible. This experienced foresight reduced and removed site hazards and meant that the workforce was better protected against safety incidents.
“There was constant communication between us and the civil contractor to make sure that they knew where we were working on any particular day of the week, and that we had a reasonable separation of the two work fronts,” Mr Coleman said.
Getting technical
Part of Zinfra’s work, alongside undergrounding the transmission cable, was completing 17 joints, backfilling their pits, installing security fencing and infrastructure, then once all cabling was complete and tested, the decommissioning and demolition of 18 transmission towers.
The concrete pits the Zinfra team were installing new transmission cabling in were 1.3m deep, 14m long and 4.5m wide and were located alongside other contractors’ work and equipment. The sheer size of the joint pits made organising site safety a major challenge.
“We had one instance where our jointers were at one of the pits and they were in full swing. It’s a 12-day timeframe to do a cable joint, and they were working under their canopy,” Mr Coleman said.
“We recognised that there were going to be issues with work that needed to happen on the road adjacent to the pit. The contractor had to seal that road for the local government tourist facility owners, and that schedule overlapped with the joiners.”
Mr Coleman explained physical separation was necessary to avoid scrapers sliding down the hill into the pit. The hazard and solution were presented to asset owner Evoenergy, who trusted and followed Zinfra’s guidance.
Site safety also included several instances of innovation from Zinfra managers.
Mr Coleman explained getting access to the pits created a safety concern, wherein access needed to be secure and any pre-manufactured ladders wouldn’t suit the specifics of the pit. Organising their own purpose-made ladders ensured the Zinfra team could access the pits safely, as well as being a more cost effective solution than purchasing premade options.
Trust in experience
Mr Kiri, with decades of experience in transmission work, said sharing his knowledge was pivotal to the success of the Molonglo project. Discussing safety concerns, not only with the civil contractors, but with the owner of the transmission assets Evoenergy, protected both the workforce, as well as equipment and the project timeline as well.
Mr Kiri’s knowledge and experience was also on hand from the beginning of the Molonglo project. Installing the cables that ran off large cable drums brought a significant problem when liaising with the other principal contractors. The civil contractor was planning on pulling the cable from a drum from the topside, but Mr Kiri knew that flipping the drum would be a better solution.
“I originally identified the cable pulling as a safety issue, because of the fact that we had two or three tonnes of cable at the end of the cable pool that would be still sitting up,” Mr Kiri said.
“We would have to somehow negotiate that cable off the drum and still be able to pull or keep pulling into the conduits.”
The benefit of Zinfra’s method, which also allowed drums to be set up staggered behind each other, saved the project extra financial fees as it shortened the time required to have a large crane onsite to lift the weighty cable drums.
“Our solution was more cost-effective. It was a lot safer to do, and we’ve got more control over the cable as it’s going in,” Mr Kiri said.
“We can also identify any problems with the cable as it’s going in, because it’s at a lower level. So if there’s a problem with the cable, we can identify it before it goes in and stop the cable pull and get the other civil contractor to take a look.”
The future of Molonglo Valley
The Zinfra team still has work ahead. The next step in the Molonglo relocation project will include testing on the complete circuit, and then beginning the dismantling of the decommissioned overhead lines.
“It’s about 9.5km of conductor that we have to lower to the ground and then wind up and dispose of, and then decommissioning and the demolition of the ground towers,” Mr Coleman explained.
As Zinfra finishes work in the Molonglo Valley, a job well done means a job unseen. All 58km of cables will have been safely relocated underground, and 18 tower demolitions and removals ahead of area remediation will mark the Molonglo suburb ready for housing subdivisions. Thousands of future residents will benefit from the trusted work of Zinfra for years to come.
This sponsored editorial was brought to you by Zinfra. For more information on Zinfra’s comprehensive range of engineering, project management, construction, operations and maintenance services please visit www.zinfra.com.au.
