Eiffage Énergie Systèmes connects Flandre Maritime substation for RTE by creating 16 underground links.

Eiffage Énergie Systèmes connects Flandre Maritime substation for RTE by creating 16 underground links.

Energy Systems Division

- 17 July 2025 - 11:11

RTE is building one of France's largest substations (400,000V over 24 ha) in Saint Georges-sur-l'Aa (59). The Flandre Maritime substation is located in close proximity to Dunkirk Harbour, Gravelines EPR2 and the future offshore wind farm, and is part of the Dunkirk region's energy transition. The new facility will replace the old Warande substation, now obsolete, and will be connected by our local experts who are in charge of building sixteen 225,000V underground links.

The future Flandre Maritime substation is the main source of power for the Dunkirk area and will support the region's decarbonization and reindustrialization drive by connecting new electricity production and consumption facilities to the RTE network. In other words, by 2023 the future 400,000V substation must be able to meet the high demand for electrical power from an industrial fabric undergoing conversion. It offers new electrical potential to support future projects in a region that has begun to move away from fossil fuels and has launched a drive to boost its industrial and economic development.

Our experts based in Verquin (62) have been appointed to take charge of the high-voltage underground lines. They are to create sixteen 225,000-volt HV links to connect the future Flandre Maritime substation to the RTE network.

"On 28 April we began the first part of the work, consisting of civil engineering, to be followed by the laying of HV underground cables (225,000 volts), fibre optics and earth cable, to create sixteen underground links. The links will include air-underground connections (single and double) from the 225 kV Flandre Maritime substation to the six new air-underground towers - extending the links on the overhead spans to Grand Colombier, Denna, Brode, Duvigneau and Gravelines substations (auxiliaries 1 and 2) - as well as four double AT links to connect the 225,000V and 400,000V Flandre Maritime substations”, explained Business Manager Christophe Lechon.

Our specialists are to build a total of sixteen 225,000V underground links, representing 10 km of links and 30 km of cable. They will also roll out 11,000 ml of optical fibre and ground cables. During eleven months of civil engineering work (from April 2025 to March 2026), they are to create 7,000 ml of markings, earthwork trenches and innovative formwork to lay 30,000 ml of high-density polyethylene and PVC sheaths. They will complete 60,000 cubic metres of earthworks, pour 1,400 cubic metres of low-carbon concrete and build 19,000 square metres of platform and runways.

Once connected, this strategic substation will be partially commissioned in the second quarter of 2026, with full delivery scheduled for 2030. The development of the vast industrial port area where the substation is located is part of the roadmap unveiled by RTE to strengthen and modernize the national EHV network. RTE plans to invest 1.5 billion euros in the Dunkirk area between now and 2030.