Inside the super sewer cleaning up London

Sep 25, 2023 | News

You wouldn’t want to be in Joel Harland’s shoes in 18 months’ time. For now, there’s just a trickle of water beneath his steel toe-capped boots, but come 2025, this culvert will be full of sewage. Lots of sewage.

It’s part of the Thames Tideway Tunnel, the £4.5bn project giving London’s creaking, Victorian drainage network a much-needed upgrade. Nicknamed the Super Sewer, the main run is 15.5 miles (25 km) long and up to 65 metres deep. Capable of storing some 1.6m tonnes of effluent, it links to the existing network, capturing overflow on rainy days and sparing the River Thames from raw sewage spills which can tot up to tens of millions of tonnes a year.

“People don’t give a moment’s thought to what happens to their wastewater,” said Harland, a civil engineer working on Tideway. “One interesting thing about building infrastructure like this is that you come to understand some of the mechanics behind how our society works. We all tend to take it for granted – me included.”

London was home to around two million people when its existing sewer network was built in the late 19th century, largely as a response to the Great Stink of 1858. The stench of human waste in the Thames became so unbearable there was talk of relocating parliament from its shiny new home in Westminster.

Today, the population has hit almost nine million, and the capital is expected to swell to 16 million by the mid-2100s. To safeguard the river into the next century and beyond, giant boring machines have been chewing their way below London in the UK’s largest water infrastructure project since privatisation. Lined with concrete, the central tunnel is wide enough for three double-decker buses, and will carry waste all the way from Acton in the west to treatment works at Beckton in the east.

For Harland, the project may have lacked the cache of a swanky high rise, but it’s proved a positive, eye-opening experience nonetheless.

“I do like working on something that is ultimately benefiting society, and will benefit the city that I live in as well,” he said. “The net impact in terms of hygiene and cleanliness of the river can only be a good thing.

Main image: William Joshua Templeton

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