Explore Hidden Hazards.

The ground beneath our feet poses all sorts of hidden hazards and although we cannot easily see them, they are ever-present, revealing themselves in dramatic and often terrifying ways.

These hazards can vary from landslides to mining collapses and from radon exposure to building subsidence, their invisibility making them inherently scary as well as difficult to perceive and therefore identify, manage and resolve. Ground hazards in the UK are synonymous with one word: Sinkholes, now used to describe any sudden collapse of the ground, varying in size and shape from potholes to gigantic chasms like the one shown above. 

Sinkholes can be caused by many different things but are often attributed to the UK's long history of mining, dissolution of bedrock such as chalk and gypsum and utilities failures in roads and drains. The potential local and community damage caused by ground collapse, landslides, radon, subsidence and/or Sinkholes is substantial and any hidden hazard in the vicinity of property or land can cause significant disruption, structural damage, insurance premium hikes and loss of asset value. 

It is for this reason that it is essential that the risks the ground poses are expertly identified, managed and resolved, to ensure they cannot impact livelihoods negatively. Although it is not (yet) possible to accurately predict when Sinkholes will occur, with advances in data and risk modelling, it is now very possible to proactively identify where sinkholes will occur, allowing those affected to mitigate the impact of ground collapse and other hazards. 

To explore these hidden hazards, use the buttons below to learn more about Sinkholes, the long history of mining in the UK and why it is always important to understand the ground

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Behind the Scenes

In November 2017, Sinkholes from Boomerang Productions and Channel 5, aired across UK terrestrial television investigating the devastating impact these geological hazards can have on people, property and investment across the UK and the globe. 

Terrafirma and our CEO, Tom Backhouse, feature throughout the series providing expertise and intelligence to the real risks faced by homeowners, the public and businesses who have been and continue to be affected by these hidden hazards. In the second episode; Buried Underground, Terrafirma visit a recent sinkhole that has collapsed in the West Midlands. 

On the 13th August 2017 a 3-metre wide and 3.6 metre deep hole appeared in a residents driveway in Wednesbury. The residents driveway, car and main building all sustained damage and an evacuation of the property was required. In this case, the sinkhole is believed to be the result of former coal mining activity. As the image below shows, there has been extensive mining in the region - leaving behind a significant, but hidden legacy of multiple extraction features. 

To learn more about this sinkhole - you can read our full blog here. To learn more about sinkholes and their impact, it is possible to catch up on the Channel 5 series here.  

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Understand Sinkholes

Sinkhole is now a broadly used term, describing any hole in the ground created by erosion processes and the drainage of water. They can be just a few feet across, such as in Neath, South Wales or large enough to swallow whole buildings, such as in St Albans, Herts. Although they’re often the result of natural processes in other countries around the world, notably Florida, in the UK they regularly attributed to industrial human activities such as mining, utilities and transport infrastructure. 

There are two basic types, those that are created slowly over time (a cover-subsidence sinkhole) and those that appear suddenly (a cover-collapse sinkhole). Naturally, it’s the latter type that create headlines, but both varieties are formed by the same basic mechanism.

Sinkholes associated with wholly natural processes do occur in the UK and are found in what is known as ‘karst terrain’; areas of land where soluble bedrock (such as limestone/chalk, brine, gypsum) can be dissolved by water. With "cover-subsidence" sinkholes, the bedrock becomes exposed and is gradually worn down over time, with the holes often becoming ponds. In the UK, this occurs readily in areas such as Cheshire, Droitwitch, Ripon and Kent. 

With a "cover-collapse" sinkhole, this same process occurs out of sight. Naturally occurring or more commonly, man-made voids underneath the surface are hollowed out by water erosion, with a cover of soil or sediment remaining above. Voids can then migrate as groundwater fluctuates seasonally; a heavy rainfall follows a storm event; or utilities fail. As the void expands, the overlying cover (often soils or sand but occasionally tarmac/pavement) can no longer support its own weight and suddenly collapses to reveal the cavern below.

Has there been an increase in UK sinkholes?

This graph shows the increase in UK sinkholes since 2000. The rise can be attributed partly by increased media coverage, however ageing utilities, changing weather patterns and increasing land re-development means subsidence and ground collapses are on the rise!

Search our Blog for information on Sinkholes in your area? 

Search our interactive map for Sinkholes in your area? 

 Recent Sinkhole in Wednesbury, West Midlands (Copyright: Terrafirma 2017).

Recent Sinkhole in Wednesbury, West Midlands (Copyright: Terrafirma 2017).

Understand Mining

What do you think of when you hear the words ‘Mining in the UK’?

Your mind may be drawn to a Sunday night in front of Aiden Turner on ‘Poldark’ and the extensive tin and copper mining industry that criss-crossed Cornwall or more likely, the vast underground network of coal mines that span large parts of England and Wales, fresh in the memories of families and local communities alike.

In reality, mineral extraction is one of the UK's greatest industrial legacies, spanning the ages of civilisation nationwide, dating back over 5000 years. Over 60 minerals have been scraped, quarried and mined from beneath our feet, defining the country we live in today. The results of several millennia of mineral extraction has inevitably left a scar on our landscape, some of which are represented in a city's stunning architecture, such as in Bath, or in dramatic landscapes such as the lead rakes in the Peak District.

It has also left hidden hazards, beneath our feet and out of sight and with a recent increase in sinkholes, subsidence and collapse, it is important we understand this industrial legacy so we can effectively identify, manage and resolve any hazards it still poses. 

Explore the mineral resources in your region

Explore how mining still defines our landscape today

What mining hazards should I be worried about?

Recorded UK Mineral Extraction

This chart visualises the known sites of extraction in the UK, categorising them by mineral type. A common perception is that mining in the UK is solely associated with coal, however, this chart clearly shows that Building stone (Chalk, Sandstone, Limestone, Clay, Sand, Slate etc), Metals (Tin, Lead, Copper, Iron) and Oil and Gas as being our dominant mineral resources. In reality, coal forms just 10% of the recorded mining sites in the UK.

Mine Entries (Coal)

This chart shows the remediation status of recorded coal mine entries (Coal Authority) in the UK, of which there are 179,000. Over 80% of mine shafts and adits have been left untreated and there are a recorded 132,000 mine entries within 20 metres of a UK property.
 Mine Shaft collapse in Tehidy Road, Camborne, Cornwall (Copyright: Terrafirma 2017)

Mine Shaft collapse in Tehidy Road, Camborne, Cornwall (Copyright: Terrafirma 2017)