The big challenge
Equans is on track to complete the expansion of the five fields at the Mercator high-voltage substation by the end of April 2023, just in time for the new high-voltage lines to go live. This highlights one of Equans’ key strengths: meticulous planning and execution within tight deadlines. “You can't just start working on a high-voltage line,” explains Didier Janssens-Petit. “Elia first needs to decommission the line, a process known as ‘cutting’. This is scheduled well in advance, So when we work on the high-voltage line, we have to do it within the predetermined and sometimes limited timeframe.”
Equans’ success in this area stems from its extensive experience, having laid thousands of kilometres of high-voltage lines with various types of conductors of every diameter. “We start by removing the old conductors, mechanically rolling them up from one mast to the next using the latest machinery. We take great care to protect everything under and around the masts from potential disruption or damage. New conductors are then installed later once the new masts have been erected.”
The dismantling of the old 150 kV masts – a necessary step for the construction of the new 380 kV masts – is also part of Equans’ remit. “We started dismantling the existing 150 kV line in August 2023, and this operation will continue until the end of February 2024. All conductors and pylons, except one, will have been removed by then for lot 1 – between Liefkenshoek and the Kallo substation. We’re waiting for the cutting of a nearby 380 kV line to safely dismantle that remaining mast. During the dismantling, we’ve had to navigate around challenging obstacles, such as the constantly active Kallo lock and a golf club. We’ve also implemented numerous protective measures for the disassembly of masts located in a minefield of utility lines. A highlight was removing two massive masts, each 117 metres tall and weighing 125 tonnes,” shares Didier Janssens-Petit.
“We faced numerous difficulties on the stretch from Kallo to Mercator, including the Rietveld Kallo nature reserve, crossing over the E17 and E34 motorways – which were completely closed during night works – and crossing over five bundled and electrified railway lines. We used a special netting structure for these railways, connected to the mast of a telescopic crane in Kallo and a scaffolding structure for protection in Beveren.”
Elia typically outsources the laying of new foundations to other specialised contractors. “At Equans, we then assemble and erect the masts. We often start by constructing manageable mast modules on the ground, which are then stacked using telescopic cranes. The construction time for a mast can range from just under a week to three to four weeks for a heavy 380 kV mast, depending on the environment and weather conditions. For this project, we assembled and erected a mast in just under ten days.” This phase will continue until the end of April 2025. Equans will start installing the new conductors in October 2024.