River Seine Cleanup for the Triathalon

How the Olympics Triathlon has been used to clean up the River Sein (Source: WIRED 2 Aud 24)

The goal of the Seine-cleansing project is to produce swimmable conditions for the people of Paris for years to come—the Olympics was just a milestone in getting there. The intense scrutiny on the Seine ahead of the triathlon has distracted from the true goal of the project: to make the river suitable for public swimming for the long term—and to better protect the river environment and boost biodiversity along the way. Teams have been working hard on the swimming plan since 2016, with the Olympic and Paralympic Games in focus as a high-profile opportunity to show off their achievements on the way to opening up the river to the public. Work has included an overhaul of outdated sewer systems and the construction of giant rainwater retention basins designed to stock excess rainwater during heavy storms and reduce the amount of untreated water flowing into the Seine. When the conditions are right, the systems put in place keep the river clean enough for bathing.

“We haven’t invested more than a billion euros just for swimming—we’ve invested it to improve the Seine’s environment in the years to come,” says Frédéric Muller, who is responsible for efforts to make the Seine safe for swimming at the Eau Seine Normandie water agency.

“[Weather] variability due to climate change is a major issue, and this will only make things more difficult,” says Dan Angelescu, CEO of water-monitoring start-up Fluidion. The company makes remote water-sampling devices that beam their readings back to a central base, and it has been working with Paris authorities since 2016 providing water analysis at the Bassin de la Villette reservoir, a separate swimming site in the north of Paris that is already open for public swimming. Experts argue that how water-monitoring is done, and what information is shared with the public and when, also has to improve. “It is crucial that bacteriological data be published daily, along with information on the associated risks.’

A big part of the clean-up operation so far has involved upgrading plumbing networks to stop moored boats and some older houses and other buildings discharging their waste directly into the river.

In the coming years, the prefecture will continue rationalizing the sewer and water treatment system, making sure that buildings are properly connected to the network and not to the river directly, and that the network has sufficient capacity to avoid being overwhelmed.