Jan De Nul Completes Belgium's Longest Microtunnel Under Scheldt River

Record-Breaking Microtunnel Inaugurated in Antwerp

Jan De Nul Group, in collaboration with partners Denys and K-Boringen, has successfully completed Belgium's longest microtunnel, a significant infrastructure achievement beneath the Scheldt river in Antwerp. The 1,288-meter passage, part of the ECLUSE industrial steam network, was inaugurated on Tuesday, October 14, 2025, by Flemish Minister for Energy and Climate, Melissa Depraetere.

This microtunnel represents a crucial step in sustainable energy transport, connecting waste-to-energy plants on the left bank of the Waasland Port to industrial customers on the right bank.

The ECLUSE Project: A Sustainable Energy Solution

The primary purpose of the newly completed microtunnel is to transport steam, valorized from waste incineration, to various companies. The ECLUSE network currently supplies steam to five companies on the left bank and, with this expansion, will extend its reach to the right bank. The first customer to benefit from this new connection will be the chemical company Evonik in Antwerp.

The project is expected to yield substantial environmental and economic benefits. It will enable Evonik to save an amount of energy equivalent to the annual consumption of more than 38,000 households. Furthermore, it is projected to decrease CO2 emissions by 100,000 to 150,000 tons per year, contributing significantly to a low-carbon energy supply for the Port of Antwerp and reducing industrial dependence on fluctuating gas prices.

Engineering Feat and Collaborative Effort

The microtunnel, boasting an internal diameter of three meters, was constructed using advanced microtunnelling techniques, which allow for the creation of underground passages without the need for open trench excavation. This method is particularly suitable for challenging environments such as river crossings.

Jan De Nul's scope of work included extensive preparatory and concrete works, focusing on the construction of the launch and reception shafts. The launch shaft on the right bank measures 15 meters in diameter and 16 meters deep, while the reception shaft on the left bank is 11.8 meters in diameter and 14 meters deep. The overall ECLUSE 2 project, which saw the arrival of its tunnel boring machine in March 2025 and the start of drilling later that month, is scheduled for full completion, including piping and technical equipment installation, by the end of 2026.

The success of this project is a result of a collaborative effort involving private and public partners, including Indaver, SLECO, FINEG, Maatschappij Linkerscheldeoever, the Port of Antwerp-Bruges, and Water-Link, with support from the Flemish government.

Impact on Belgium's Energy Transition

The completion of Belgium's longest microtunnel marks a pivotal moment in the country's energy transition strategy. Minister Depraetere highlighted the project's importance, stating, 'The Ecluse tunnel under the Scheldt proves that investments in sustainable energy are good for both climate and industry. It makes companies less dependent on fluctuating gas prices in geopolitically unstable markets. And it anchors our energy-intensive industry towards a fossil-free future. That, in turn, is good for preserving our jobs. We will continue to encourage projects like this.'