Huge River Seine stormwater basin opens ahead of Paris Olympics

Government and Olympics officials on Thursday inaugurated the Austerlitz basin – a massive underground cistern that's a key part of efforts to enmake the River Seine remains clean enough to host swimming events during the Paris Olympics.

The interior of the Austerlitz basin, 30 metres underground, which will play a key role in cleaning up the Seine river in time for the Olympics. © Maria Paula Carvalho/RFI

After three years of work, the 30-metre deep basin next to Austerlitz train station is ready.

Paris Mayor Anne Hidalgo, Sports Minister Amelie Oudea-Castera and Olympic organising committee head Tony Estanguet on Thursday marked the completion of the project, which will start operations before the end of the month. 

The basin is one of five big anti-pollution plants due to come on stream in the weeks leading up to the Games. It can hold 46,000 cubic metres of water, the equivalent of 20 Olympic swimming pools.

It will be used whenever heavy rain falls on Paris.

Pollution levels have become a major issue ahead of the Olympics, whose marathon swimming events and triathlon are to be held in the Seine if the water stays clean enough.

"In Paris, our dream was to bathe in the river like the Parisians used to do 100 years ago. The Olympics gave this project a huge boost," Hidalgo said Thursday.

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Sewer system update

The basin is hooked into the Paris sewer system, which collects rainwater along with sewage and domestic wastewater. It gets overwhelmed during heavy rainstorms.

Valves release excess water containing untreated sewage directly into the Seine, which means the river regularly contains levels of E.Coli and enterococcibacteria that are dangerous for human health.

By providing extra storage capacity, the Austerlitz basin should reduce the number of discharge incidents each year, though it will not solve the problem entirely.

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Olympic organisers have acknowledged that a major storm could lead to the Seine being out of bounds even with the basin operational.

Besides rainwater surges, another issue is wastewater from barges and boats using the Seine and the Marne.

A 2018 law requires the boats and barges that line the Seine to be hooked up to the city's sewers to stop them flushing directly into the river. Officials said that by March almost all were following the rules.

Hidalgo and President Emmanuel Macron have promised to take a dip before the Games to demonstrate it is safe

(with AFP)