Lessons from Parisian Sewers – Sewer Balls

Lessons from Parisian Sewers – Sewer balls

Author : Amanda Siqueria

On a recent trip to Paris, I convinced my husband and in-laws to come with me on an adventure into the underworld. Enter the sights and sounds of the Paris Sewer Museum (Musée des Égouts de Paris). Ever since I had read about the museum in a book (‘An Underground Guide to Sewers’, but Stephen Halliday) I had wanted to go.  

Tunnel cross sections in Parisian Sewers

Learning about the different tunnel cross sections used in Parisian sewers, Source: Author

Paris Sewer Museum (Musée des Égouts de Paris)

The museum is attached to a working sewer station that lets visitors explore the evolution of this hidden French infrastructure. Let’s just say, it’s a 4D experience, the fourth dimension being ‘smell’. That said, there was so much to look at and learn that the initial ‘wall’ of the odour was soon forgotten.

Picture of a sewer ball

Our first encounter with the sewer ball, Source: Author

Sewer Balls

Out of all of the things that we saw, the artefact that stood out the most were the ‘sewer balls’. The giant balls made of iron or wood were used to clear debris from the large diameter sewer tunnels.

Size of sewer ball

Me and my best mate, Source: Author

Sewer ball design

A lot of the tunnels were designed to be ‘visitable’, I.e. to provide manual access to the structure for inspection and maintenance purposes. In tunnels where this access was not provided, these ‘sewer balls’ were used, most often in siphon and outfall parts of the network. The diameter of the balls was slightly smaller than the diameter of structure they were inserted into so that they would be able to pass through unobstructed.

Diagram of sewer ball

Diagram of sewer ball use in Parisian sewers, Source: Brochure from Musée des Égouts de Paris 

Their unique design allowed for a small gap between the ball and the base of the tunnel through which the backed-up wastewater passed at high pressure and flushed out the sediment in front like a jet of water. The ball was then removed from the end of the structure and cycled through the tunnel until the structure was cleared of debris.

Teams of sewermen in the 1920s using various apparatus for clearing the sewers. Note picture of the sewer ball being used. 

Source: Halliday, S 2019, An Underground Guide to Sewers, Thame & Hudson

Lessons from history

Visiting this sewer museum, we learned not only about the sewer balls, but also the many other feats of engineering that were applied to wastewater collection and treatment in Paris. Although the balls themselves are no longer in use, it was interesting to see many of the same challenges that modern wastewater networks have, also existed at the time the network was first constructed. In the case of silt and debris removal, manual and physical methods are still a big challenge in modern sewers. Hashtags like #binthewipe and #weirdthingsinpipes illuminate some stark examples of modern sewer misuse. The challenges continue to grow in number with the increasing number of wet wipes and other rag material entering the network.  Perhaps a sewer ball revival is on the horizon? Either way, it’s an interesting reminder of the ingenuity of engineers in solving problems, and the need for awareness raising when it comes to sewer misuse.

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