The Austerlitz basin was inaugurated on Thursday, May 2nd in Paris by the mayor of the city, Anne Hidalgo, and other political officials. The enormous dimensions of the structure are overwhelming, with more than thirty meters deep and fifty in diameter. At the foot of the dizzying staircase leading to the bottom of the basin, one feels crushed by the volume above. The fresh concrete smell is noticeable, and any noise echoes off the walls. The twenty pillars anchoring the cylinder fifty meters into the ground give it a cathedral-like appearance. After forty-two months of construction and a budget of 90 million euros, the underground Austerlitz basin has been unveiled in the 13th arrondissement of Paris.
Situated between the Austerlitz train station and the Pitié Salpêtrière hospital, the structure is set to be operational by the end of May following a testing phase. It is a model of civil engineering in a dense urban environment. A 2.50-meter tunnel was dug under metro line 10 and the RER C, and then under the Seine to connect the basin to two wastewater collection shafts on either side of the river. With a capacity of 50,000 m3, equivalent to 20 Olympic swimming pools, the basin will store a portion of the sewage and rainwater that the old sewer system discharges into the Seine when it becomes saturated during heavy rainfall. The collected water will be pumped back into the sewer system once it can be treated.
The Austerlitz basin is a key infrastructure project for the public authorities in Paris to improve the water quality of the Seine River. While it does not guarantee the readiness of the Seine for swimming events such as marathon swimming, triathlon, and paratriathlon this summer, it is part of a long-term plan initiated in 2015 aiming to make the river swimmable by 2025. Currently, around a dozen sewer overflows release a total of 2 million m3 of wastewater into the river each year during heavy rains, a significant reduction from thirty years ago. Once the basin is in operation, there will only be two overflows per year, with only the most severe rain events exceeding the basin’s capacity.
The mayor of Paris, as the main funder of the project, ensures that the Austerlitz basin will significantly reduce pollution in the Seine River and help achieve the long-term goal of making the river suitable for recreational activities. This project is part of a larger effort by the city and the state to clean up the river and open it for swimming after more than a century of restrictions. The basin is a crucial step in this plan to improve water quality and reduce pollution levels, ensuring a better environment for both residents and visitors to the city.
