First of the Concrete Giants Laid at Sea for the New Sea Barrier in Genoa

Over 90 caissons will be laid for the construction of the new barrier.

The operations began early in the morning. The reinforced concrete giant, as tall as a 7-story building, was towed into the sea and taken to the point where it would be sunk. This marks the laying of the first of over 90 caissons that will form the approximately 4 km of the first phase of construction of the New Breakwater in Genoa. In this case, the giant is 21.7 meters tall, 25 meters wide, and 40 meters long; in the future, the dimensions of the other caissons will reach heights of 33 meters, widths of 30 meters, and lengths of 67 meters.

The laying of the first caisson on the seabed – the event took place starting on May 24th – is a key moment in the construction of the project entrusted to the Consortium “PerGenova Breakwater” (led by the Webuild Group together with Fincantieri Infrastructure, Fincosit, and Sidra) and occurs one year after  the start of work, while activities continue in the open sea for the construction of a project that will profoundly change  Genoa‘s role as a logistics hub in Europe.

One Year of Work: The Unstoppable Construction Site

Over 230 people are currently involved in the construction site, with about 1,000 people expected to be involved in completing the project, and over 130 supplier companies engaged in this first year of work during which the construction site of the New Sea Barrier in Genoa has never stopped. Since the start of the consolidation work in May 2023, activities have continued without interruption. It all began with the demining operations, which affected some areas, followed by the journeys of the ships that, first from Piombino and then from Spain, brought gravel to Genoa for the consolidation of the seabed of the New Barrier.

Overall, over 1.4 million tons of gravel have been laid. Gravel is the material used to build the consolidation columns that will support the base of the dam, built at a depth of 50 meters, with 7 million tons of rocky material. During this first year of work, approximately 4,000 columns have been completed. On the base, a structure composed of cellular caissons, prefabricated reinforced concrete structures up to 33 meters high, 30 meters wide, and 67 meters long will be placed.

The caissons, those giants that will stop the sea

The caissons will form the body of the New Sea Barrier. Their construction is one of the most complex parts of the entire project. Firstly, each caisson is built directly at sea, in floating basins set up in the port of Vado Ligure. The construction process involves setting up a metal formwork on the floating platform, positioning spacers and the reinforcement cage, and then pouring the first concrete accompanied by the assembly of the iron that will constitute the reinforcement of the caisson itself. The caissons are cellular, meaning their section is made up of cells, “boxes” that will be filled to allow the caisson to sink. Once the transport at sea is completed, the caisson is then positioned at the exact point assigned to it and reaches its final location. At that point, once the caisson is filled, a cover is placed on top of the caisson, on which the superstructure is built, on which the wave barrier wall rests, the most visible part of the dam, designed expressly to reduce the impact of waves.

All these activities are carried out in open sea, increasing their complexity. This is why a temporary barrier has been built in the port of Vado Ligure to protect the construction areas. The same Vado Ligure barrier is composed of 5 caissons, placed side by side, and of smaller dimensions than those that will constitute the main barrier of the New Sea Barrier. In addition to being giant structures, the caissons also embody the principles of sustainability applied to the construction of the dam. Once the caissons are made, they are made impermeable using a special concrete mix. They are filled with recovered and recycled inert materials, including those derived from the demolition of the old dam and port dredging. As for the concretes used in their construction, an innovative mix has been developed to significantly increase their impermeability. Sustainability measures are also implemented for the protection of the ecosystem both outside and inside the marine construction areas: among these, an “air bubble curtain” around the construction site to reduce noise and safeguard marine species, and collaboration with the Genoa Aquarium for the temporary relocation of marine organisms located along the entire axis of the new dam, in coordination with scientific operators and expert marine biologists.

One step at a time towards the construction of a great work

The New Sea Barrier will be built further offshore than the current one, thus guaranteeing a different configuration of port accesses and also allowing larger ships (400 meters in length) to maneuver safely in the port areas. This represents a paradigm shift for the port of Genoa which – also thanks to the completion of strategic transport infrastructures such as the Third Giovi Pass, high-speed rail between Genoa and Milan – will complete the strategic process of connecting the region with the rest of Europe.