Basin of Austerlitz

In Paris, after 3.5 years of construction, the colossal rainwater basin “Bassin d'Austerlitz”, with a depth of 30 m and a diameter of 50 m, is entering its final phase. When completed in Spring 2024, the impressive underground reservoir will hold circa 46,000 m³ of water, equivalent to the volume of 12 Olympic-sized swimming pools. Basin of Austerlitz is an extraordinary project in a city as densely populated as Paris.

Aim of the project

The aim of this €90 million project: to improve the hygienic quality of the Seine water, especially with a view to the 2024 Summer Olympics. It is to ensure that swimming competitions can take place in the Seine and to make the river accessible to citizens for swimming as part of a future regional plan.

Relieve pressure on the Paris sewage network

Currently, when there is heavy rainfall in the metropolis, the city's old sewers can no longer handle the additional water flow. This causes rainwater to mix with sewage and the excess water flows into the river on a large scale, resulting in pollution. The new reservoir will collect excess rainwater and prevent Paris' sewage network from being overwhelmed, thereby preventing contaminated wastewater from entering the Seine. Stored water can also be added to the river in dry summer months when the water level of the Seine is low.

In addition to the structural challenge of the rainwater basin, a 600 meter-long tunnel with a diameter of 2.50 m was also built leading into the tank, acting as a channel to allow water to flow out.

Pecavoid^® ground heave solution

As the soil conditions are dominated by clay, the water absorption over time can lead to swelling and increased soil volume below the building. To prevent damage to the base slab, Pecavoid^® is used to ensure effective load decoupling. The load decoupling element serves as a stable formwork during concreting; when a predefined maximum load is reached, it collapses and creates a cavity.

Project video: