Man-made sinkholes costing over £300,000 to fix

Human activity has had a disastrous impact on ground stability, inflicting misery on unsuspecting victims across the UK and beyond, as sinkholes continue to open up in the voids where our ancestors once mined the mineral-rich earth. 

The problem is likely to continue, as Tom Backhouse from Terrafirma explained in the Channel 5 Documentary series “Sinkholes”: “There are 170,000 coal mineshafts in the UK and over 400,000 non-coal mineshafts – and less than 5% are capped properly in a way that wouldn’t collapse.” 

This is not a new problem, but the sheer scale of it and the costs involved of it are increasingly making the headlines – and took centre-stage in the second episode of the documentary series that aired this week : “Sucked Under”. 

A sinkhole that opened up in Newcastle upon Tyne was just one example of how the costs and complications can quickly spiral out of control. In Gosforth, residents awoke to a 30ft deep sinkhole at the end of a driveway, which turned out to be an entrance to a disused coal mine that had been capped and forgotten over 100 years ago. 

Unfortunately, a large, unstable sinkhole can’t just be filled in overnight. From digging it out and backfilling with rock, to topping it off with 65 cubic metres of reinforced concrete, it took 7 months to make the Gosforth sinkhole safe again – at an eye-watering cost of £300,000, as well as ongoing inconvenience and worry for residents.

…And this isn’t just a residential issue. Following the discovery of an abandoned chalk mine beneath Pinner Wood School in 2015, the school has been closed for almost 2 years, whilst extensive work took place to fill the voids and make the school safe to use again. 

However, it is not always possible to fix the problem and, as seen in the case of Jacqueline Close over 50 years ago, entire streets can end up being demolished following the discovery of unstable, abandoned mines beneath the properties. 

The UK isn’t alone in its battle against sinkholes 

The problem isn’t isolated to the UK either, as revealed in the case of Bayou Corne, Louisiana. Following extensive salt mining activity over 40 years ago, 58 caverns were left behind once the brine had been successfully extracted. 

When one of them failed in 2012, 1,000 tons of earth and trees were sucked underground in a void the size of 2 football pitches. The nearby town was quickly abandoned and only 15 of the 159 residents now remain in the once-idyllic ghost town. The mining company has denied responsibility, and only time will tell if another of the 57 remaining caverns will also fail.

Interactive mapping tools are making it easier to see the full extent of the risks

Terrafirma are working across the UK to understand the ground and provide detailed information to conveyancers and their clients. 

The following TerraSearch® products are now available on tmconvey to order against residential and commercial properties, both including professional opinion that helps to make it quicker and easier for conveyancers to convey important information to their clients:

TerraSearch® Coal Extra is a regulated ‘Con29M-Compliant’ coal mining search offering an equivalent to the Coal Authority report, including a professional opinion of all coal mining risks and CON29M questions and additionally alerting to 55 further mining hazards.

TerraSearch® Assess is a single search that comprehensively assesses the risk to a site (property and land) from all 60 mining hazards, including past, present and planned extraction.

Terrafirma have also released new interactive mapping tools to make it easier for the general public and their conveyancers to see the full extent of the risks beneath their door steps – simply by adding in their postcode. 

For more information, you can watch the “Sinkholes” documentary series here : http://www.channel5.com/show/sinkholes/