York & North Yorkshire

Sinkhole-prone city of Ripon gets 3D model

Sinkhole in Ripon Image copyright PA
Image caption Twelve properties in Ripon were evacuated after a 20ft (6m) deep hole appeared in 2016

One of the UK's most sinkhole-prone cities is to use 3D-mapping techniques to help planners cope with the problem.

Ripon sits above a layer of gypsum, a water soluble rock which leads to the formation of large underground caves.

Following sinkhole collapses near existing homes, the British Geological Survey is creating a 3D model to help planners select safe sites for homes.

Local planners are under pressure to build new houses in the city after failing to meet government targets.

A Harrogate Borough Council spokesman said: "Any tool to better understand the geology is very helpful but the onus is still on any developer to establish it is safe to build on that land."

Image copyright Crown Copyright Ordnance Survey
Image caption The city has been split into zones depending on geology

The number of new homes built in the Harrogate district has fallen short of the government annual target of 669 new homes, according to the BBC Data Unit.

The council has earmarked land for housing development within an area of known as Zone C that is susceptible to sinkholes.

Rebecca Burnett, of the council, said: "Being in that zone does not preclude development, it just means that we have to undertake quite a lot of extra work to illustrate development is possible.

"If it proves not to be safe then there won't be development."

Image caption The 3D-map is being developed by the British Geological Survey
Image copyright BGS
Image caption The work is mapping Ripon from above and below ground

Dr Vanessa Banks, of the British Geological Survey, said by 2020 it was hoped the map would be available to help scientists, developers and planners.

The system would not "give all the answers" about where housing could be built but would show "where the greatest uncertainty" was for further investigation.

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Image copyright Other
Image caption This sinkhole in an alley prompted the closure of a nearby Sainsbury's supermarket in 2018

For more on Ripon's sinkholes watch Inside Out on BBC One Monday 11 March at 19:30 and afterwards on iPlayer.

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