The Principality of Monaco is making every effort to ensure that its extension project has the lowest impact on the environment. A goal that is currently taking shape in the preparatory operations of the underwater construction site, which will be the future Anse du Portier district.
The site is preparing for the arrival of 18 concrete caissons, currently being manufactured in Marseille’s large sea port. Bouygues Construction recently stated that containers of polluted material were first extracted using the Mimar Sinan hydraulic excavator, similar to a Tiger dredger. This particular excavator is equipped with a cable crane and an ecological container, which avoids extracted materials being suspended and mixed in the water. These sediments were sent by boat to the Envisan company’s specialized treatment centre in La Seyne-sur-Mer. The operations began on the 18th of April 2017 and were completed on the 3rd of November 2017.
In parallel with this first phase, unpolluted sediments were extracted using a suction dredge on the Francis Beaufort ship, which can work on seabeds up to 56 metres deep. Bouygues Construction specifies that this dredge works without overflow, that is to say, without rejecting the water it sucks up with the sediments, so it will not increase the turbidity of the water.
The dredge then transports the sediments to a location, specifically chosen not to encroach on the marine fauna and flora, and deposits the sediments under the ocean. This site is 200 metres deep and is located in Monaco’s territorial waters. The sediments are released at a depth of 77 metres from the bottom, again to minimize the creation of turbidity. This operation, which began on the 12th of October 2017, should be completed by the end of February 2018.