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Engineers tackle 130t ‘concreteberg’ in London sewers

concrete 1 (4) cropped

Thames Water engineers have arrived on site to begin examining a massive 130t mass of concrete clogging North London sewers.  

The 100m long mass discovered under Hall Street in Islington last week is the result of people dumping concrete into the sewer system. 

Thames Water confirmed that work to remove the “industrial amount” of concrete will cost several hundred thousand pounds. Engineers are expected to have to use manual tools to chip away at the concreteberg, including pneumatic drills and high-pressure water jets. 

Thames Water operations manager Alex Saunders said that the blockage was the worst Thames Water has ever encountered. The concrete has set into the Victorian-era brickwork. “Normally blockages are caused by fat, oil and wet wipes building up in the sewer but unfortunately in this case it’s rock-hard concrete,” he said. “It’s in there and set to the brickwork, so we need to chip away at it to get it removed.” 

“This is not the first-time damage has been caused by people pouring concrete into our sewers but it’s certainly the worst we’ve seen. It’s very frustrating and takes a great amount of time and effort to resolve. We’re now doing everything we can to deal with it as quickly as possible, making sure our customers don’t have to suffer because of this mindless abuse of our network.” 

Concrete 2 (4)


Source: Thames Water

The 100m long, 130t blockage sits at the junction of Gosling Road and Hall Street, Islington

A spokesperson for Thames Water said that the 100m long obstruction is not completely blocking the sewer, but that capacity in the area is reduced.  

Thames Water encountered a similar problem in 2017, when it deployed a 12,000psi jet tanker with a 130m hose to blast away the other concrete blockages, allowing sewers to return to normal flow – however other sewers had to have entire sections removed and replaced where the concrete was too difficult to blast out.  

An investigation is currently underway to find the source of the Hall Street concreteberg, as well as claim back costs of clearing it.  

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Readers' comments (1)

  • 130t of concrete represents approximately 50 cu.m.
    How can such a deposition go unnoticed? The culprit should be sought.

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