ÐÇ¿Õ´«Ã½

In the past six months, the UK has seen multiple high-profile geological events. Two sinkholes, one of which was 20m long, closed a main road and caused houses to be evacuated in Godstone, Surrey. In Merthyr Tydfil, south Wales, a sinkhole estimated at 10m to 12m deep wreaked similar havoc in a quiet cul-de-sac. Also in south Wales was the Cwmtillery landslide. On New Year’s Day, a major embankment serving the Bridgwater Canal in Cheshire collapsed. More recently, a rockfall occurred on a residential road on the Isle of Wight, during a spell of unusually warm weather. 

These events are not completely out of the ordinary. After all, the UK is an island with varied geology. However, such incidents are increasing in frequency, and it is widely recognised that this trend will continue. This will mean a greater role for geotechnical engineers in investigating the potential for such events and their causes. 

Geological risk profiles are changing. We expect an increased focus on ground investigation at the outset of projects

One factor linking these geological events is almost certainly climate change, leading to unusually heavy rainfall. The saturation of ground and erosion of soluble material below the Earth’s surface creates voids. When a void collapses, a sinkhole can suddenly appear at the surface. The risk profile for sinkholes varies nationwide – parts of South-eastern and North-eastern England are considered more vulnerable due to underlying beds of chalk and gypsum. This brings the potential for swift, catastrophic collapse in a built-up area. To minimise such risks, it is important to adequately investigate ground stability at the outset of a construction project, and check for tale-tell signs such as differential settlement and heave.

A weather cycle of extreme heat or heavy rain can negatively impact slope stability. This can result in the unwanted movement or collapse of railway and road embankments and cuttings, as well as triggering natural landslides. Embankment designs now need to take account of the geological risks associated with climate change. Where routine monitoring and inspection of such structures fail to reveal problems arising from these weather cycles, those affected will want to know what information was available to their geotechnical engineering adviser and whether reasonably competent advice was provided. 

Flooding continues to pose a major threat to developments and infrastructure. Often geotechnical advice is sought when seeking to assess groundwater levels and soil infiltration rates as part of devising drainage design strategies. If mistakes are made, flood damage which may have otherwise been avoidable could form the basis of claims against consultants.

Claims

Where geotechnical engineering problems arise, complex, high-value disputes against professional advisers can follow. In December 2024, the Technology and Construction Court gave judgment in such a dispute involving substantial sums. This concerned a residential development site affected by chalk dissolution features, which caused differential settlement issues. The developer only became aware of this during the course of the build and incurred significant costs in ground remediation works. The developer sued two firms of engineers for their alleged failure to adequately advise on the risk profile of the site. The first engineer had produced a phase one geo-environmental report – a desk study type of report – and the second had undertaken intrusive ground investigations using equipment, including cable percussion boreholes.

>>Also read: The Procurement Act is here - what does it mean for the construction industry?

>>Also read: Get your clause into it – contractual responsibility for specific risks

The second engineer reached an out-of-court settlement with the developer, whereas the first fought the case through trial. The first engineer managed to defeat the claim on matter of causation, despite a finding that it had been negligent in preparing its phase one report. The court found that the developer had not relied on the negligent advice from the first engineer and that it would have still proceeded with the instruction of the second engineer for the intrusive ground investigation, even if the site had been flagged as medium or high risk in the first engineer’s phase one report.

The case also neatly illustrates the vital need for competent geotechnical engineering advice about undeveloped land that is being considered for development.

More disputes?

The government is currently shaking up the planning regime. Its goal is to increase development in the newly classified grey belt, by essentially relaxing planning policy for some existing green belt sites. The pressure to build housing stock and commercial premises on previously undeveloped land could lead to an increase in the number, type and scope of claims involving geotechnical engineering issues. Projects located in higher-risk areas, vulnerable to sinkholes and dissolution features in our changing climate, may well lead to more property damage and construction disputes arising from sinkholes or differential settlement.

Geological risk profiles are changing. We expect an increased focus on ground investigation at the outset of projects, as well as on the stability assessment of slopes, embankments and cuttings. However, not every project or investigation will be financed and resourced adequately. There are always commercial pressures. Where the extent of a ground investigation is constrained, or something is overlooked, severe consequences can follow. We therefore anticipate a greater number of disputes in this arena.

Giles Tagg is a partner and Alessandro Morgan-Gianni a senior associate at international law firm DAC Beachcroft