Environmental Science & Engineering - www.esemag.com - May 2005
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Hi-tech project defends the Riviera


Philippe Porcu
For most, Monaco means glitz and glamour, racing cars and casinos. But aside from its reputation as a destination for the international jet set, the principality is an extremely dynamic state, with 32,000 inhabitants and a busy port which has recently been expanded. One of the world’s smallest states, Monaco is installing the largest watertight container ever built.

“The government under the impetus of HRH The Sovereign Prince decided to construct a new barrage in order to enlarge the Hercules Port. This will provide it with new infrastructure and protect the harbour from the strong east winds,” explains Philippe Porcu, assistant technical director for the sanitation division at the SDAU, Monaco’s urban development service. “The sea is very deep in the harbour with extremely thick silt, making a traditional solution impossible, so we came up with the idea of a semi-floating barrage along with a more traditional counter pier,” he explains.

The barrage weighs in at 160,000 tonnes and was delivered in August 2002. It measures a massive 352 metres long, 28 metres wide and 19 metres deep, and was constructed over three years at Algeciras in Spain and towed 1,500 kilometres to its final position by ship, a sea voyage that took almost two weeks. In addition to providing a breakwater, the barrage also contains a four-level “underground” car park, dry dock, two passenger terminals and other commercial and administration premises.

“The barrage is anchored to terra firma using a kind of ball and socket, weighing 700 tonnes, which allows the pier to move while remaining attached,” Mr. Porcu explains. “At its tip, it can move up to 15 metres laterally and around 1.30 metres up and down. The construction is also held to the sea floor by anchors. The counter pier stands firm on pillars on the other side of the port.

“The port is on the same level as Monaco's purification plant; previously, water from both boats and the port couldn't be evacuated using gravity, and it was necessary to bring in trucks to pump their waste,” he explains. “But the barrage and harbour are equipped with pumping units that enable all wastewater from the barrier, from ships berthed there and from those permanently moored in the port to be sent for treatment. This is very significant in terms of protecting the environment - our main goal. Previously, ships disposed of everything at sea, but now we can treat all the effluent as well as rainwater and run-off, thanks to the hydrocarbon separators we've installed,” he explains.

A series of underground service tunnels have also been constructed to carry wastewater, drinking water, electrical and telephone cables. Because they are situated below sea level, these galleries are also equipped with special pumps to remove any leaked water. These pumps are equipped with “skirts” to lower the evacuation level to just 1.5 centimetres from the floor.

In addition, the entire network has been equipped with a remote surveillance system. “Now we can monitor any potential problem with the pumps, stations or separators, and deal with any situations that may arise as rapidly as possible,” Mr. Porcu explains. “We can also monitor flow rates and water levels and are able to operate various valves remotely to optimise the functioning of the principality’s whole sanitation network, which also handles effluent from the neighbouring districts.”

Pierre-Louis Odouard is project manager for Somoclim, the Monacobased firm responsible for installing the pumps on the Monte Carlo port network. “This installation was a real challenge, in terms of both setting up the operation as well as the materials used,” he says. “Because the networks and stations are below sea level, we had to construct ballasts around the pump stations, and the installation had to be done by divers. Other constraints meant we had to use special materials. The pumps are industrial seawater models, with an epoxy coating, equipped with anodes. The prefabricated units are made of reinforced polyester with stainless steel parts, and all piping is polyethylene.”

When the project is finished in 2008, the whole port will have been entirely redeveloped and its facilities doubled. It will provide berthing to large yachts and cruise ships; new jetties and commercial premises are planned as well as the restructuring of the north and south harbour basins.

Anatomy of a barrage
The semi-floating barrage contains: On land, there is: This technology was recognized as “Best Real-Estate Project” by the Jury at Barcelona Meeting Point 2002, and won a Leonard Award at the Immotech show 2004 in Geneva.

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