Paris 2024 Olympic Games: “The water of the Seine will be fresh… but clean”, Emmanuel Macron reassures three months before the opening of the Games

The President of the Republic continues to reassure about the cleanliness of the Seine. MAXPPP – Alexis Sciard

Emmanuel Macron, who promised to swim in the Seine in preparation for the Olympics, assured Tuesday that the river's water would be “clean”, on the occasion of the inauguration of a rainwater treatment station in Champigny-sur-Marne, a crucial link for the holding of certain events.

Being able to swim in the Marne and the Seine is "one of the events of the century", declared the Minister of Sports Amélie Oudéa-Castéra during this inauguration in the Val -de-Marne.

"We are ready, on time, on D-94" of the Olympic Games this summer in Paris, and "we will also be there for our heritage", she added.

The Head of State also congratulated himself on his account 60~/em>. "Mobilized together, State and elected officials, we are getting there. The water of the Seine will be fresh… hellip; but clean", he wrote on the social network. Before launching, support frozen emoticon: "I can confirm it for you!"

Étape clé pour rendre la Seine baignable, la station de dépollution des eaux pluviales à Champigny-sur-Marne est prête ! Mobilisés tous ensemble, État et élus, nous y arrivons.

L'eau de la Seine sera fraîche… mais propre.

Je pourrai vous le confirmer ! 🥶

— Emmanuel Macron (@EmmanuelMacron) April 23, 2024

Emmanuel Macron has in fact committed on several occasions to swimming in the Seine on the occasion of the Games, without however setting the date of the meeting or specifying whether he will do it in public.

An essential work for holding the tests in the Seine

Downstream of the rainwater treatment plant (SDEP) inaugurated in Champigny, the Marne flows into the Seine, where open water swimming events and the swimming portion of the triathlon are to take place this summer.

These are giving the organizers of Paris-2024 a cold sweat, the cleanliness of the river depending heavily on the weather: in the event of a major stormy episode in the preceding days, which would lead to an evacuation in the Seine of the mixture of rain and wastewater, they could be postponed or even canceled, as was the case during test events last August.

The measures taken to clean the Marne and the Seine should also make it possible to swim there, which has no longer been possible since 1970 in the first case and since 1923 in the river the capital.

The objective of the SDEP is to return 700 liters per second of water into the main tributary of the Seine, i.e. "the equivalent of a Olympic swimming pool per hour", said Olivier Capitanio, president of the Val-de-Marne departmental council, present at the inauguration ceremony.

A cost estimated at 53 million euros

With the Austerlitz basin, built in Paris and inaugurated at the beginning of May, the Champigny station, work on which began in the fall of 2020 at a cost of more than €53,000. million euros, represents a major work.

Fed by two water intakes, it is smaller than Austerlitz (8,000 m3 compared to 50,000 m3), but has a dual functionality: in the basement, two lobes with a depth of up to 20 m and a diameter of 35 m receive rainwater, one to store it, the other to clean them in three steps.

First, screens to separate the waste. Then, settling blades to separate the water from the sand and mud. Finally, the main technological innovation lies in the presence of around a hundred ultraviolet lamps to obtain, assure its operators, 99.9% healthy water, free of bacteria.