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Pinner Wood School, London

Analysing the stability of 19th Century chalk mines

  • London, United Kingdom

    London, United Kingdom

Securing the safety of pupils and teachers

After a large hole opened up in the car park of Pinner Wood School in London, Harrow Council commissioned our specialist engineers to conduct further analysis. What did they find? School buildings and playgrounds were sitting on top of a disused chalk mine.

The analysis also showed that some of the tunnels had partially collapsed, leading to a risk of further holes opening on the surface. The findings led the council, the school governors, and the Pinner Wood leadership team to close the school on 23 March 2017.

Since then we have been conducting in depth surveys of the site, together with Geoterra—a geospatial engineering consultancy—to determine the extent of the mines and ensure they are made safe.

When work had completed, Sarah Marriott, the headteacher, welcomed project director Dr. Clive Edmonds, project manager Stuart Chandler, and site engineers Natasha Withers and Harry Gordon to the school to help the children understand what had happened.

Clive explained that the mine likely dates from at least the early 1800s. As is common for chalk mines of this age, there are no mine abandonment plans, so we had to discover the extent and state of the mine workings. This was confirmed by 3D-laser surveys, above and below ground, using the most up-to-date technology available.

The school reopened only nine months after its original closure.

At a Glance

  • Harrow Council
Meet Our Team

Stuart Chandler, Associate

Ground instability poses health and safety risks to people and can lead to damage of existing and new services, infrastructure, and buildings.

Stuart Chandler


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