For more than 150 years, Monaco has adapted its urban planning to the narrowness of its two squared km territory, which is constrained between mountains and sea. The Principality is constantly shaping its urban landscape through major structural projects in order to meet the requirements of its demographic growth, economic attractiveness and sustainable development. In the last century, from the 1950s onwards, 20% of the Principality’s surface area was reclaimed from the sea. To continue to support and accompany its developments and respond to the responsibilities and challenges it faces, Monaco must continue to develop the ground area of its territory. The continuing evolutions of construction technologies and the new architectural concepts they make possible, allow the development of ever more innovative and daring structures using more efficient and sustainable methods and materials. That is why the Prince’s Government launched a call for applications in May 2013 for the construction of a new district through an urbanisation project at sea.
Photo © Principauté de Monaco – SAM L’Anse du Portier – Renzo Piano Building Workshop – Valode & Pistre Architectes – Michel Desvigne Paysagiste
SAM L’Anse du Portier, with Bouygues Travaux Publics MC, won this tender. The realisation of this project is an architectural and technical challenge. It responds to the Principality’s ambitious energy transition objectives regarding its commitments to reduce greenhouse gas emissions (becoming carbon neutral by 2050) and to the need for growth in a dynamic and modern country. Part of the challenge is to design and apply construction methods which minimise the impact on the natural environment in agreement with Monaco’s global sustainable development project. The developed areas must make it possible to build a district at the forefront of a new responsible urban energy management, and of new construction methods whose constant objective is to reduce the impact on the environment.
The future Anse du Portier district. Photo © Principauté de Monaco – SAM L’Anse du Portier – Renzo Piano Building Workshop – Valode & Pistre Architectes – Michel Desvigne Paysagiste
“Monaco must find the means to ensure its growth and development while being mindful of the environmental impact they may have… Building on the sea while preserving the environment…”. This principle, defined by H.S.H. Prince Albert II himself, is the philosophy and golden rule of this new extension of the Principality’s territory.
It has led the designers and builders of the project to imagine and implement innovative methods for its realisation. The construction of the maritime infrastructure is a laboratory in many respects, especially for its environmental engineering.
Below sea level, as well as on land, various methods and features have been devised to help nature take back the newly created spaces. Applying rational energy management to the life of the new district is also an important part of the project.
These principles are part of the DNA of the programme for the construction and exploitation of this new space.
It defines the concept of urban biodiversity which is at the heart of the project.
An essential district for the growth of the Principality, created under controlled environmental conditions
Mid-December 2019 symbolically marked the completion of the land of the Anse du Portier district.
A view of the offshore extension on December 16, 2019. Photo © SAM L’Anse du Portier
On 17th December, earthmoving machinery completed the filling of the 440,000 m3 lake that had formed inside the belt of caissons1.
It only took nine weeks and the addition of 750,000 tonnes of sand to complete the filling operation.
The extension of the Principality’s territory is now a reality2.
The filling process began in mid-October 2019. Photo © SAM L’Anse du Portier
Since the launch of the project, this offshore extension has been designed, built and animated in coherence with the natural environment.
Therefore, rather than building on every square metre gained at sea its designers have reintroduced a natural ecosystem into the newly created space.
Concretely, out of the six hectares of new land, one hectare will be dedicated to a wooded park.
The overall plan of Anse du Portier. Photo © SAM L’Anse du Portier
Since the start of the project environmental issues have been taken into consideration before beginning each step in the implementation of the project.
Engineers, architects and environmental specialists have thus developed their solutions based on the triptych “Avoid, Reduce, Compensate”, to:
- limit the impact of preparatory works by adapting operations to environmental conditions (displacement of species and adaptation of the shape of the maritime infrastructure among others),
- reduce this impact during the course of the work (implementation of suitable devices and methods: anti-turbidity screens and acoustic screens)3,
- compensate by attributing ecological functionalities to the designed structures to help restore the ecosystem present prior to the work.
This principle is unprecedented in a construction site of this scale (six hectares) and complexity (construction at sea from -50 metres).
This makes Anse du Portier a laboratory for eco-design. And it also makes it possible to develop sustainable construction solutions that are sometimes unheard of, and that are always adapted to the local environment.
Beyond that, this principle encourages the appropriation of the artificial structures by the natural environment and allows the reintroduction of biodiversity within the urbanisation.
Artificial, submerged structures, shaped to foster development of biodiversity
The caissons of the eco-district’s protective belt have a crucial role.
These structures, which are for the most part submerged, are located between depths of -20 metres and the surface, an area that is very important for marine biodiversity.
The caissons are both marine and terrestrial structures that rest at -20 metres and emerge six metres above the water. Photo © Bouygues TP & SAM L’Anse du Portier
They have two functions:
- protecting the eco-district from the power of the swell and the waves,
- integrating devices that can accommodate life.
Hydraulic engineers and environmental engineers have therefore worked together to develop solutions that satisfy both:
- the mechanical criteria essential to contain the effects of the sea on the structure,
- ecological measures to encourage the colonisation of the submerged parts by fauna and flora.
These symbiotic functionalities have been studied, for more than a year in some cases, to measure the durability of the properties of the caissons and simultaneously the real benefits in terms of efficiency for the development of the species.
Several features were selected.
At the bottom and on the façade of the caissons:
- superimposed gabions were installed at the base of the caissons in order to start the vertical ecological corridors.
The eco-designed panels are attached to the front of the caissons. A total of 168 will be installed. Their dimensions are 1.5 x 2.5 metres. Photo © SAM L’Anse du Portier
- eco-designed panels were hung on the front side of the caissons. They provide shelter for some species and habitat for others.
In the Jarlan chambers4:
- Reliefs were added in the lower part of the concrete to allow algae, aquatic plants and molluscs to attach.
1. The relief created during the construction of the caisson. 2. Eco-designed panel fixed after the caisson has been installed on the backfill. 3. Habitats intended for marine fauna and flora installed in the Jarlan chambers of each caisson. Photo © SAM L’Anse du Portier
- artificial habitat structures of different sizes and shapes were installed.
he variety and repetition of the different arrangements around the caissons and in the Jarlan chambers meet the functional needs of the many species that make up the fauna and flora at these varying depths. These needs differ in terms of habitat, nursery, resting, hunting, shelter and travel conditions between -20 metres and the area around the surface that is constantly being exposed and submerged due to the movement of the sea.
Solène Robic, who heads the team responsible for environmental issues at Bouygues TP, points out that “there is no ‘turnkey’ solution. Many systems only target one species at a time.” She adds: “With the creation of the maritime infrastructure, we cannot limit our work to just one species. Our thinking extends to an ecosystem. Therefore, we have daily R&D work. We are constantly thinking about how to attract biodiversity and develop the attractiveness of the whole area.”