Spring rains that once might have spilled sewage into the River Thames are instead filling up London’s new “super sewer” – a massive network of tunnels designed to bring the city’s plumbing into the 21st century.
Tideway, the company formed to build the new infrastructure, began construction more than a decade ago and announced the connection of the new system in February. It cost more than $6 billion, funded by private capital up front and paid back by a surcharge on Londoners’ water bills over the coming decades.
“We think it’s really good value for money,” said Tideway’s Taylor Geall. “£25 a month is quite a small price to pay, we think, for a cleaner river.”
London has a combined sewer system, which means sewage and rain flow into the same pipes. Storms frequently overwhelmed the system, spilling around 40 million tons of sewage into the Thames annually. The “super sewer” will “virtually eliminate” that problem, according to Tideway.
Some of the new tunnels are more than 200 feet underground and as wide as three London buses. Since it went online late last year, the new system has already intercepted almost 7 million tons of sewage bound for the river.
The project also includes seven new public parks, including one at the foot of the Blackfriars Bridge. When finished later this year, it will be named Bazalgette Embankment, in honor of the 19th-century engineer Joseph Bazalgette, who designed London’s first sewer system.
Standing on the Blackfriars Bridge on a sunny April morning, Tideway’s Taylor Geall evoked the crisis that spurred Bazalgette to action in the summer of 1858.
“It was pretty gross. There was an event called The Great Stink, where pollution of all sources–sewage, but also runoff from industry and abattoirs, all that gross stuff–was essentially tipped into the Thames. The Thames was poisoned,” he said. “The smell was so bad in Parliament that they needed to solve the problem. So, they tasked the Victorian engineer, Joseph Bazalgette, and he built over a thousand miles of brick sewers in London.”
Still in use today, Bazalgette’s sewer system eradicated cholera in London. Since his time, however, London’s population has grown from 2 million people to more than 9 million, and the city has paved over natural areas that used to soak up runoff. Tideway’s “super sewer” averts another public health crisis like The Great Stink, Geall said, but it does not solve the problem of what to do with an ever-increasing flow of water into London’s sewers.
“We certainly think more needs to be done,” said Geall. “This project buys London time to be smarter about what it does with rainwater, because going forward it isn’t sustainable to be putting rainwater into the sewer system, because it fills up.”
Climate change is making heavy rainfall more frequent in London. The “super sewer” is designed to last 120 years, with climate projections in mind. To avoid another massive expansion, Geall said Londoners should build more green infrastructure to absorb rain before it overwhelms the system.
On a sunny spring day, kayakers share the Thames with industrial ships and water taxis. The return of recreation to the river is another benefit of staunching sewage overflows, said Geall.
“It’s certainly going to be a much nicer environment for rowers, kayakers,” he said. “Anecdotally, we hear all sorts of stories of rowers picking up condoms and all sorts of gross stuff on their oars. And now that we’re operational, we really believe that that is going to be a thing of the past.”
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Chris Bentley produced and edited this segment for broadcast with Ciku Theuri. Bentley also adapted it for the web.
This article was originally published on WBUR.org.
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