Sustaining Paris — Eugène Belgrand

Photo: Sebastopol trunk sewer, Paris, France; postcard from Les Egouts de Paris website.

Eugène Belgrand provided Paris with a reliable supply of clean water and modern sewers. By the middle of the 19th century, hundreds of years of accumulated rubbish blocked the antiquated subterranean drains beneath Paris, some dating from the 1600s and earlier, and the only source of water available to city residents was the polluted Seine River, unless they could afford to pay for water delivered by cart from sources in the surrounding countryside. Baron von Haussmann, the Prefect charged with urban renewal during the Second Empire, envisioned an extensive new system of pipes distributing clean water throughout the city and cavernous conduits for drainage beneath newly paved streets. These would be the vital organs of a transformed Paris. “Pure and fresh water, along with light and heat, would circulate like the various fluids whose movement through the body and replenishment sustain life itself,” he wrote.

It fell to Belgrand, his chief engineer, to translate Haussmann’s vision of Paris as an “organic” city into bricks and mortar. Paris’ topography presented Belgrand with his greatest challenge. Many of the neighborhoods of the Right Bank are low-lying and naturally poorly-drained. The name Le Marais, for the neighborhood between the Hotel de Ville and the Place de la Bastille, translates as “the swamp.” And, it would be another forty years before engineers could employ efficient water pumps for supply and drainage. Therefore, Belgrand had only the force of gravity to deliver clean water and carry away runoff from rain and washings from the streets.

To improve the water supply, Belgrand built new aqueducts and reservoirs to tap sources in the Vanne and Dhuis rivers. To improve drainage, he diverted the flow in the sewers away from the quays along the river and into a huge central drain. The new collecteur drain runs northwest from the city center to Clichy and discharges into the Seine far downstream at Asnières. By taking a short cut through a large meander in the Seine, Belgrand’s new collecteur drain discharges at an elevation two and a half meters (about eight feet) below the river level at the Notre Dame cathedral, in the middle of the city. The lower outlet elevation translates into more gravity power to move water through the drainage network, more power to drive the larger, better functioning organs of a transformed Paris.

At the end of his career, Belgrand claimed, with some satisfaction, that “[t]he magnificent sewers of Paris have always been a source of public fascination and have been honored with illustrious visits. Not a single foreign monarch or distinguished person has left Paris without visiting the sewers.” Visitors attending the Paris Exposition in 1867 flocked to see the modern technological wonder that Belgrand had constructed below the streets. Belgrand’s sewers still attract tourists. However, today’s visitors are more likely drawn by the prospect of seeing the menacing subterranean world depicted by Victor Hugo’s Les Misérables. The hero’s climatic escape takes place through the decrepit ancient sewers that Belgrand labored to replace. Ironically, the novelist’s compelling image persists in spite of the engineer’s success.

Eugène Belgrand is one of the 72 engineers and scientists named on the Eiffel Tower.

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William Nuttle

William Nuttle

Navigating a changing environment — hydrologist, engineer, advocate for renewable energy, currently writing about the personal side of technological progress