Why do former mining areas pose a unique risk? 

The UK has a long history of mining activity, including coal, tin, copper and other mineral extraction, leaving a legacy of underground workings across many regions. This activity has led to a legacy of underground voids, which may eventually lead to collapse, particularly in shallow areas.  

While the collapse appears sudden, there are some notable signs of underground voids, such as cracking, dips and depressions on the surface. The impact of a collapse not only has health and safety implications, but can also lead to significant costs for homeowners, developers and local authorities.  

It’s important to note, however, that mining activity is not always the cause of ground movement. Several factors, such as soil moisture levels, geological conditions and poorly compacted made ground can also contribute to settlement and subsidence.  

That’s why having a deeper understanding about the site’s history and ground conditions is crucial before any remediation works are considered.  

UK homeowners can find out more about ground movement risks in former mining areas from the Mining Remediation Authority website. The British Geological Survey (BGS) also has a mining hazard database providing information for planners and developers. 

Ground movement is a symptom of the underlying cause 

Visible signs, such as cracks appearing in walls, sloping floors or uneven surfaces can cause concern, but they don’t explain why the movement is occurring.  

If the symptoms are treated without addressing the root cause of ground movement, it can lead to ineffective repairs, recurring problems and significant costs. Cosmetic or surface repairs may only temporarily fix the surface damage and if the underlying ground movement continues, the problems are likely to reappear. 

Understanding the exact ground conditions is vital to ensuring successful remediation works. Once ground engineers fully know what’s going on beneath the surface, they can then determine the most appropriate repairs.  

On that note, it’s important that any problems are identified early. Early intervention can help identify developing issues before they lead to more extensive damage or significant disruption. 

How is ground movement investigated? 

Where ground movement is suspected, a professional site survey, such as Mainmark's in person site survey, can help determine whether further investigation is required. It includes a visual inspection, which looks for signs of subsidence, e.g. cracks in walls, sticking doors and windows.  

The engineer will also take measurements to identify signs of movement and assess whether further monitoring may be required. Further investigations may be needed to determine the soil conditions beneath the property to determine if the soil is strong enough to support the foundation loads.  

Historical data including geological maps and mining records can also provide valuable information about the site.  

This information will then inform engineers whether the moment is ongoing, what the root cause is and how risks can be managed effectively. 

Addressing the underlying cause 

Once the root cause has been identified, the appropriate remediation work can take place. The repair method depends on the extent of the damage and the size and layout of the property.  

Mainmark specialises in modern techniques such as resin injection or computer-controlled grouting, which offer a faster and more efficient alternative with minimal disruption to the occupants of the property. These methods can help fill voids, strengthen loose soils and help restore load-bearing capacity.   

Understanding ground conditions is key 

The recent incident in Coalsnaughton illustrates how significant ground movement can affect homeowners and their properties. The area has a complex geology and mining history. Several coal horizons exist at varying depths, with some relatively shallow. This is in addition to a deep abandoned mine beneath the village. Historical pillar-and-stall and other former mine workings are also present beneath the area. The underlying ground is further complicated by a mixture of strong and weak sedimentary rock, which creates variable ground conditions across the region.  

Recognising that ground movement is a symptom, not the root cause is key, as is identifying issues early to prevent further damage or extensive costs.   

If you have any concerns about ground movement, or you suspect it may be happening on your property, contact Mainmark today.