XXL pipes for new city territory in Monaco

The huge pipe spools are transported on heavy goods vehicles to the harbor basin.
The huge pipe spools are transported on heavy goods vehicles to the harbor basin.

Monaco is the second-smallest country in the world, with an area of ​​2.2 km², after Vatican City. However, while the population density in Vatican City is 2,200 people/km², around 19,000 people live in the same area in Monaco. It is obvious, that a permanent housing shortage dominates the Principality. In response to the housing shortage, the Monegasque government resorts to an unusual method: the Principality is being extended by a new, 60,000 m² district. For this, a well-fortified platform consisting of concrete and sand is filled up in the sea. AGRU Kunststofftechnik is supporting the revolutionary urban development project with XXL pipes, which serve as outfall pipes for clarified wastewater and stormwater.

Directly in front of the Grimaldi Forum, the most desirable part of the Principality, Monaco is expanding into the Mediterranean. The construction company commissioned to build a six-hectare complex in the sea in the so-called “Anse du portier Monaco”. The two billion euro project will change the topography of the Principality of Monaco forever. When completed in 2025, the “Anse du Portier Monaco” will house apartments, shops, gardens and a marina.

Land reclamation by landfill

The first steps were already taken in 2016, by relocating protected marine species in order to not affect the coastal ecosystem. Since then, the foundations have been filled with 600,000 tonnes of sand from Sicily. The land thus created must withstand the tides and seismic forces. For this purpose, the new district will be secured with caisson walls, which enclose the land heaped up like a gigantic bulkhead. Each caisson weighs about 10,000 tonnes when filled with quarry material. For this purpose 2.87 million tonnes of quarry material are delivered by ship. After the planned four and a half years of construction of the foundations, the new coastal promenade will be situated 6 m above sea level.

Tailored pipe system in XXL format

The foundations also contain the necessary infrastructure of the new district. AGRU supplies several hundred meters of HDPE XXL pipes in the dimensions of OD 2500 mm and OD 1400 mm in SDR 26 for sewage and stormwater infrastructure from the two large-diameter pipe plants in Austria and the United States. For the pipe connection, AGRU also provides special large flanges made of a specific steel quality. The production of the extra large fittings and pipe spools is carried out by the installation company onshore close to the site, by means of butt welding. AGRU has provided for this the required welding machine, product design and technical support. Due to the large size of the prefabricated pipe spools, they are transported on a barge to the site for offshore installation.


The installation on the cliffy seabed is demanding for men and material. Because the harsh conditions of salt water, ocean currents and rocky terrain is a difficult environment for any material, the AGRU XXL piping system and the associated fittings made from PE 100-RC had been chosen by client and main contractor. The high resistance to slow crack growth of PE 100-RC pipes and fittings resulting in a better point load capability were required to increase safety and service life under these extreme operating conditions. In addition, the PE 100-RC pipeline is the best choice for this offshore pipe project, because of its corrosion resistance and flexibility. The pre- fabricated pipe spools are lowered to the seabed, after adding ballast weights to the pipe spools, in a pre-excavated trench. On the seabed the pipe spools are connected by flange connections together by divers.

AGRU makes an important contribution to the successful implementation of this pipe installation in a very sensitive area by providing intensive technical advice, assistance with pipe layout and laying technology as well as on-site welding training.


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