Boskalis undertakes an array of dredging and land reclamation projects across the world. These projects can face numerous challenges that stem from scarcity of sand or environmental restrictions that prevent the disposal of excavated or dredged material.
In response, we have devised innovative working methods that enable us to transform resources that were previously considered unsuitable for building – such as fine sand, silt and clay – into usable construction material. Through various techniques, we seek to overcome challenges posed by the varying and unpredictable properties of these types of materials.
Where we use locally available materials, for example as the fill for a reclamation area, the objective is twofold. Firstly, we seek to increase the bearing capacity of the soft fill so that it is accessible for our
equipment to perform the necessary soil improvement processes; and, secondly, we ensure the site has minimal residual settlement and is eventually fit for its future use– perhaps as a port or for further
construction – once handed over to the client.
During 2024, as part of a joint venture, Boskalis completed dredging of the trench for the Fehmarnbelt tunnel that connects Germany and Denmark across the Baltic Sea. As part of efforts to comply with environmental considerations, dredged materials were re-used to reclaim approximately 185 hectares of land adjacent to the Danish and German coastlines and the tunnel entrances. The dredged material from the tunnel trench comprised various sands, clays, silts, gravel and boulders which partially segregated when hydraulically
dredged. Following the placement of the soft fill, we undertook a process known as ‘dry capping’ in which the softer materials are cautiously covered (capped) with the stiffer dredged material or sand to enable access.
On a large-scale project in Singapore and some other project locations, we have extended this methodology to include the installation of prefabricated vertical drains and the application of a surcharge to compact the soil. These processes all support the stabilization of the reclamation area making it accessible for plant
equipment and, ultimately, suitable for other purposes such as construction, thereby resulting in the beneficial use of soils that were previously discarded as waste.
Due to their different properties, predicting the settlement characteristics of soft soils can be challenging. When excessive settlement occurs, more sand may be needed to compensate and bring the reclamation
to the required level. Boskalis is currently testing methods of optimizing this process using artificial intelligence (AI). The AI tool enables us to make precise predictions about the nature of the settlement of the dredged material, thereby minimizing the quantity of sand required to optimize the reclamation.
