Londoners know all too well what their city looks like from above. Knowing how the River Thames meanders through the city and where places are located in relation to it is key when navigating the capital.
Of course, just as they know what’s above the surface, Londoners are also familiar with the tunnels and stations below the surface from their London Underground maps. But what they may not realize is that there is actually a ‘second River Thames’ that runs below the one we are more familiar with.
The official name for this ‘second river’ is the Thames Tideway, and it flows from Acton in Ealing, West London, to Abbey Mills in Newham, East London. It lies about 65 meters below the surface and extends over a distance of 25 kilometers in total.
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The Thames Tideway, however, is not actually a ‘second river’, as a recent article in The times put it. It is actually a ‘super culvert’ that is in effect built to act as a second river paralleling the path taken by the River Thames.
Work on the sewer began around six years ago after plans were approved to replace an old sewer built in the 1860s when London’s population was only a fraction of what it is today. The current system struggles to cope with the 39 million tonnes of wastewater Londoners produce each year, so this £4.2 billion project was envisioned to take its place.
Every year sewage leaks into the Thames due to the outdated infrastructure currently in place. With just 2mm of rain, Victoria’s sewage system begins to overflow, but it is hoped that by 2025, when construction is complete, this will no longer be a problem.
When completed, the tunnel will be the largest sewage transfer and storage tunnel in the UK, with a diameter of 7.2 metres, large enough to fit a lorry or double-decker bus.
The project includes the construction of six main tunnel segments and several shafts and portals. The project also includes the installation of new pumping stations and other infrastructure.
The tunnel is being built using a TBM, which is capable of digging at a speed of up to 30 meters per day. Upon completion, the project is also scheduled to extend further east towards Beckton via the Lee Tunnel.
If all goes to plan, the project could reduce the amount of sewage seeping into the Thames by more than 90 percent. This will undoubtedly leave the Thames looking and hopefully smelling much better on the surface.
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