A London water provider is asking people to please, please, stop pouring concrete down their drains.

The consequences are heavy: Thames Water says a "concreteberg" the weight of a blue whale is blocking three Victorian-era sewers. "It goes without saying that pouring concrete down the drains into our sewers isn't going to do any good," Thames Water said.

The mass is longer than a football field and weighs a whopping 115 tons (or almost 105 metric tons).

"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," Alex Saunders, the operations manager of Thames Water, said in a statement.

And it's going to be a huge pain to remove. Thames Water says it's expecting a two-month process that will cause traffic disruptions in London's Islington neighborhood, around the corner from City, University of London.

Tankers are going to be standing by around the clock to pump out raw sewage so that the area doesn't get flooded with waste, the company says.

London's sewer system has seen numerous blockages in recent years — though typically they are "fatbergs" — masses of fat, oil and wet wipes. In 2017, workers discovered a 143-ton (130 metric ton) fatberg in London's Whitechapel area.

And as the BBC reports, "last year Thames Water was called to clear 42,000 blockages caused by fat and non-biodegradable matter, a 6% increase on 2017."

But this one is expected to be particularly complicated because it's made of concrete. The workers will need to literally chip away at the giant block, using a number of tools including jackhammer pneumatic drills and high-pressure jets.

The company has made it clear that being forced to deal with concrete blockages is a waste of time and money. It's expected to cost hundreds of thousands of pounds to unblock.

"It's very frustrating and takes a great amount of time and effort to resolve," Saunders said. "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."

The company says investigators are looking into how the concrete got into the sewer and hopes to recover some of the costs. "This is money which could have been spent on investing in the network and helping customers in vulnerable circumstances," the company says.

Fatbergs have become objects of fascination for some members of the public in London — last spring, the Museum of London put part of the Whitechapel fatberg on display. It's now part of the museum's permanent collection and is continuously livestreamed.

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