Work began last week to place the sand for the new Anse du Portier 'eco district'. The area that is being created along Monaco’s shoreline is being protected by a newly installed 500-metre-long belt of caissons that weigh 10,000t when ‘empty’.
Monaco is a narrow 2km2 strip of land that is constrained between mountains and the sea. Reclamation has played an important role in extending the usable area since the 1950s. The current project results from a May 2013 call for applications to build a new district on reclaimed land. The tender was won by SAM L'Anse du Portier with Bouygues Travaux Publics.
The protective marine structure surrounding the future district is made up of 18 caissons that absorb the energy of the swell and the waves into specially designed damping chambers. The caissons are trapezoidal structures each measuring 28 by 33 by 26 metres. Underwater, 20 metres below the surface, the caisson belt rests on backfill and emerges 6m above the water. Each of the 10,000-tonne caissons exceeds 20,000 tonnes once ballasted in its final position,.
The operation to place the sand is expected to take until mid-December. The quarry sand – which comes from Marseille in France and Piombino in Italy – is arriving by boat, with two bulk carriers each arriving on site twice a week to complete the 750,000-tonne order.
Part of the challenge that has been set for the project team is to adopt construction methods aimed at reducing the impact on the environment and to build a district that is at the forefront of responsible urban energy management.
The belt of submerged caissons has been designed as a habitat for fauna and flora, incorporating features to encourage colonisation by plants, algae and marine animals.
Measures to promote the development of biodiversity were implemented from the start of the project, along with provision for continuing research and development.