In 2011, Dunkerque LNG entrusted a tunnel boring project to a consortium led by Bessac that included Soletanche Bachy France. The 5 km long structure with an interior diameter of 3 metres built at a depth of 45 metres will channel warm water from the Gravelines nuclear power plant to the LNG terminal, where it is used in the regasification process.

Before starting the operation, the tunnel boring machine spent several months at the Bessac workshops, where it underwent the required adaptations. A new cutting wheel was designed to bore through Flanders clay and installed on the earth pressure balance TBM. Also prior to tunnelling operations, Soletanche Bachy France built the launching shaft (diaphragm walls at a depth of 65 metres) and the pumping station.

In late 2012 and early 2013, Soletanche Bachy Fondations Spéciales (previously Soletanche Bachy Pieux) improved the soil under the areas where the three-liquefied natural gas (LNG) storage tanks were to be built. The operation was needed to avert the risk of loose silty sand liquefaction and to compensate for the heterogeneous composition of the hydraulic backfill.

The soil was vibrocompacted and ballast was added. The soil under the regasification station was also improved.