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Taking the plunge - The divers building Monaco's extensions

 

 

 

 

 

 

 

 

MONACO

Principality of Monaco - SAM L'Anse du Porte - Renzo Piano Building Workshop - Valode & Pistre Architectes - Michel Desvigne Paysagistes

It’s no exaggeration to say that extending land territory in Monaco has always been an uphill battle. The Principality has historically faced the unenviable task of adapting its planning around the narrowness of its 2 km2 territory sandwiched between the Alpes-Maritimes and the Mediterranean.

Indeed, since the 1950s, 20% of the Principality’s surface area has been reclaimed from the sea to meet the rising demands of demographic growth and a constantly evolving economy while also ticking the box on sustainable development, a factor which HSH Prince Albert is passionately in support of. 

The challenge to create new land mass continues with the ongoing offshore eco-district extension on the Anse du Portier site. Such development calls for ever more cutting edge technology to deliver the new district to exacting standards, yet it wouldn’t be possible without human endeavour in the shape of highly trained Class II-A divers carrying out a myriad of crucial underwater works and observations.

A feat of architecture

The stakes are high; this mammoth architectural and technical feat is duty-bound to encompass Monaco’s commitment to reducing greenhouse gas emissions - Monaco has pledged to become carbon neutral by 2050 - while at the same time minimizing any negative impact on the surrounding natural and marine environments.

SAM L’Anse du Portier and Bouygues Travaux Publics MC jointly rose to this challenge, installing around 50 divers on rotation since the beginning of 2018 to assist on different missions providing assistance to underwater equipment and technical controls for engineers and technicians on the surface. The first divers actually started work in 2015, compiling early environmental impact studies, and many will continue long after construction is completed as part of ongoing ecological monitoring missions.

Marine biologists and scientific divers have also been given an unprecedented role in establishing protocols for the protection and relocation of flora and fauna and species including noble pen shell clams, Posidonia flowering plants and Lithophyllum algae from the construction site. The entire area is covered by two anti-turbidity screens, separating the work site from the adjoining marine protected area, with the hope of guaranteeing the delicate ecological balance of the new district.

These expert divers have three main areas of responsibility: supporting underwater equipment and surface operators, civil engineering and ensuring the smooth running of the works and the highest quality of the final construction through regular checks.

The human touch

One of their most crucial, and perhaps risky, undertakings is to observe and guide the installation of 27-metre high caissons – watertight chambers which are open at the bottom, with water kept out by air pressure to allow sub-aquatic work to be carried out. They must assess whether the caissons, which weigh an incredible 10,000 tonnes, are correctly in place (there is a 10 cm margin allowed) before they are permanently ballasted into position. The divers also ensure that accurate data from 20 metres below sea level is available to technicians. While GPS and topographic monitoring clearly play an important role here, it is the divers’ detailed observations following a tour of the base of the concrete mass which are pivotal.

‘We considered for a while computerizing the entire levelling process but we quickly realised that even under these particular conditions, human intervention is necessary,’ explains Antoine Renaud, of Eiffage Génie Civil Maritime in Monaco. ‘Divers are essential for ensuring the proper functioning of the device.’

In essence, they guide the chute discharging aggregate on the backfill and inform surface operators about the quality of distribution. They also intervene on any ‘jamming’ (clogging of materials in the conduit), ensuring the proper execution of the mission and that the desired result is achieved. The radio link between the divers and the operations manager on the surface allows the leveller operators to follow the progress and make necessary adjustments in real time from the pilot barge.

Once each caisson is immersed, the plates on which the cables connecting it to the tug boat are fixed must be removed underwater. It is also necessary to dismantle the steel elements that were supporting it and reconstitute the surface of the caisson by applying a specific protective coating of Epicol T that guarantees it is watertight. Yet again, the skill sets of the divers are decisive.

As is typical for many land-sea extension developments, several existing networks for rainwater, pumping and discharge of seawater needed diverting and new ones were created with the diving teams installing outfalls – large diameter pipes – of different sizes. The displacement of the Larvotto outfall used for rainwater management has led to the installation of new three-metre diameter pipes 300 metres long at depths ranging between -32 to -6 metres. This type of installation requires divers to create a perfectly level foundation before they can install and interlock different sections of the pipes using a radio link between the crane operator on the surface and the diver, who is sometimes 30 metres below the water’s surface.

In addition, divers continually observe the site to record how the project is going, adhering to verification practices which guarantee that the execution of operations complies with performance objectives, good building practice is respected, the environment is preserved and equally importantly, everyone is safe. Not surprisingly, this detailed and minutely observed surveillance involves long hours of underwater inspections and accuracy checks.

A dive can last up to three hours, with five teams taking turns for 18 hours at a time under strictly controlled conditions. In addition to diving equipment, each diver carries lighting, radio equipment and a camera. All dives are rigorously regulated; a specific permit is required and valid for only one activity for a maximum of one week if the mission remains the same, takes place in the same area and uses the same staff. Since 2018, more than 500 diving permits have been issued. Safety is of paramount importance and during all dives, an exclusion zone around the underwater work areas is mapped out and enforced.

Vast responsibility

The divers’ responsibility extends to verifying all underwater equipment used and the devices installed. This includes checking the hulls of barges, ships and smaller boats used on site, inspecting anti-turbidity screens and their fastenings and impermeability as well as maintaining tools and machines to save time and avoid having to remove or replace heavy machinery with lifting equipment more often than absolutely necessary.

‘Make no mistake about it,’ adds Antoine Renaud, ‘unscrewing a cross-head screw is a simple task at home but doing the same underwater with gloves on and cumbersome equipment at a depth of 20 metres in order to dismantle the protective casing of a leveller is a whole different business.’

It tells you everything you need to know about these incredibly skilled individuals when you consider that their collective role between January 2018 and the end of February 2019 saw them spend an astonishing 2,841 hours and 57 minutes underwater during a total of 2,203 missions.

 

- Karen Hockney