Understanding Sinkholes: Causes, Risks, and Solutions
Sinkholes are natural depressions or holes in the ground caused by the collapse of a surface layer. While they can occur gradually, sinkholes can also appear suddenly, posing serious safety risks and damaging infrastructure, properties, and utilities.
What Causes Sinkholes?
Sinkholes typically form in areas with soluble bedrock, such as limestone, gypsum, or chalk, which can be dissolved by water. Common causes include:
- Natural erosion: Rainwater, slightly acidic in nature, percolates through soil and dissolves the underlying rock over time.
- Fluctuating groundwater levels: A sudden drop in the water table can destabilise supporting material.
- Poor drainage or leaking utilities: Water main breaks, faulty drainage systems, or old sewers can saturate and erode subsurface material.
- Construction or mining activity: Human interference through excavation, drilling, or dewatering can weaken ground support.
Why Sinkholes Matter
Sinkholes pose multiple challenges:
- Structural instability for buildings and roads
- Risk to public safety and property
- Disruption to transport, utilities, and development plans
- Legal and insurance implications for landowners and developers
The Godstone Sinkhole
In February 2025, a sinkhole opened up on the A25 in Godstone, Surrey, causing immediate road closures and significant delays for local residents and commuters. Engineers on site reported that a collapsed sewer line likely contributed to the ground failure.
This incident underscores how hidden infrastructure issues, combined with susceptible ground conditions, can suddenly disrupt critical transport routes, and pose safety risks. Had a ground investigation been carried out earlier, particularly involving geophysical survey techniques, this void may have been identified and mitigated before it reached the surface.
Assess, Mitigate and Manage
At Earth Environmental & Geotechnical, we offer a range of geotechnical and environmental services to assess, mitigate, and manage the risks associated with sinkholes:
1. Ground Investigation Reports
We provide detailed desk studies, intrusive site investigations, and borehole testing to identify underlying geological conditions and voids.
2. Cavity and Void Detection
Using geophysical techniques such as Ground Penetrating Radar (GPR), Electrical Resistivity Tomography (ERT), and Microgravity Surveys, we can detect subsurface anomalies before visible sinkhole collapse.
3. Sinkhole Risk Assessments
Our engineers produce site-specific reports highlighting the risk of sinkhole development, with recommendations for construction, remediation, or avoidance.
4. Remediation Strategies
Where sinkholes or voids are detected, EEG can propose practical solutions—from grouting and compaction to structural reinforcement or redesign.
5. Monitoring and Compliance
We support long-term monitoring plans and compliance with local authority or planning requirements, ensuring client projects are safe and robust.
Protecting Your Site and Investment
Understanding sinkhole risks is essential whether you are a developer, local authority, contractor, or landowner. EEG has the technical expertise, national presence, and multidisciplinary team to guide you through every stage—from investigation to resolution.
To understand how our team of experts can support your project, please contact our team today via headoffice@earthenvironmental.co.uk or call one of our offices local to you.
