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Invasion of the square manholes

Dutch manufacturer Kijlstra is hoping to bring a small revolution to the UK with its precast square manhole units.

Kijlstra’s manholes are cast in its Dutch and German factories before being shipped to sites where they can be installed quickly and cheaply as a modular system.

The system offers standardised quality, minimised health and safety risks and efficient installation. Using precast manholes means less downtime on site waiting for concrete to go off, says Kijlstra director Hugo de Waal.


The units are precast with a self-compacting concrete that offers superior strength, meaning around 40% less concrete can be used compared to traditional manhole construction.
The UK presents “very good opportunities” for the product to be used, says de Waal.

Crucially, the manholes are watertight even under great pressure.

That means better protection against leakage, which de Waal diplomatically says is “sometimes a problem in the UK”.

Kijlstra’s manholes have so far been approved by Thames Water and Scottish Water. While there is often resistance to the unfamiliarity of a square-shaped, pre-cast manhole, says de Waal, people are quick to convert their opinions once they see how easily the system is installed.

“It looks different - that’s the main problem. But from a technical point of view it doesn’t matter whether a manhole is round or square.”

Still, de Waal hopes to see British attitudes changing over time. After all, he says, “50 years ago all manholes in the Netherlands were also round. And now everything is square”.

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