To cope with exponential traffic growth, the airport hub wanted to build a third runway, reclaiming 650 ha from the sea. A project on an unprecedented scale, it faced a number of challenges. Firstly, an environmental challenge: it was impossible to use the dredge-and-fill method, which would have re-suspended the sometimes polluted marine deposits in the soil and threatened the ecosystem.

The project was therefore carried out using Deep soil mixing, the only solution capable of treating the soil in place without manipulating it, and thus protecting the endemic dolphin species. Soletanche Bachy’s expertise in this field is unrivalled. A low-carbon binder was also used. Secondly, a technical challenge: the immediate proximity of the airport meant that teams had to work at limited heights, without the airport’s activity ever coming to a halt.

In addition, most of the work was carried out from barges, by sea, using CSM workshops specially designed by all the parties involved in the project, and thanks to the decisive know-how of Soletanche Bachy’s Material Department, Eurofrance’s Material Department, TEC System and the Korean experts from Sambo E&C.
A total of 16 workshops were mobilized 24 hours a day, at every stage of the project. This CSM operation was the largest ever carried out not only by BSGL, but also by the Soletanche Bachy Group.

It involved laying 92,000 2.8 x 1.2 m panels at depths of between 15 and 20 m, through marine deposits and loose alluvium. These operations required extensive
testing, drilling and sampling.