The Carnot seawall in Boulogne-sur-Mer (Pas-de-Calais), dating back to the 19th century, has not had any reinforcement work done for over twenty years. The wall, which was built in sections between 1880 and 1958 and stretches for over 3 km, plays a key role in protecting the town and its port.
 
Teams from Eiffage were chosen to fill in any gaps, produce and install rockfill and concrete blocks. Eiffage Génie Civil, Eiffage Travaux Maritimes et Fluviaux and Herbosch-Kiere, a subsidiary of Eiffage Benelux specialising in port, river and maritime works, have an equal role in the contract.
 
584 concrete blocks
Launched in April of this year, work began on land with the production and storage of the 584 concrete blocks weighing between 33 and 50 tons needed to complete the works.
 
Some of the blocks were installed in October using Atlantis, a barge owned by Herbosch-Kiere that is practically the only one of its kind in the world. The barge has its own crane installed on board. Using GPS, it can install the concrete blocks from the sea, directly at the base of the wall. By the end of October all the blocks were installed.
 
Works have now been put on hold due to the risk of swell. They will start again in the spring, with the installation of 3,300 m3 of geo-blocks (geo-textile pouches filled with concrete poured on site) and repair work on 5,000 m² of existing masonry. Work will be carried out at low tide and should be completed by December 2018.