Jun 1, 20234 min read

Is HS2 Contractor Align to Blame for Buckinghamshire's Recent Sinkhole?

Investigations are ongoing into the origin of the recently discovered sinkhole and the potential influence the contractor excavating in the area may have had on the local geology. Sinkholes are a naturally occurring phenomenon and are not always linked to man-made influence. While no one wants to be held accountable for unfavorable circumstances, the connection between the firm and the emergence of the large sinkhole has raised eyebrows.

High Speed Two (HS2) Ltd is a public company, owned entirely by the UK’s Department for Transport (DfT), and it is the company building Britain’s new high-speed railway: High Speed 2 (HS2). The project is divided into phases, with the first phase scheduled for completion between 2029 and 2033, pending approval for later stages. The railway will stretch from London to Manchester, with additional branches to Birmingham and the East Midlands. HS2 will be the second high-speed line in Britain, after High Speed 1, which connects London to the Channel Tunnel.

HS2 Rail Line Map

HS2 Ltd contractor, Align, acknowledged the appearance of a significant sinkhole near a river in Buckinghamshire. The sinkhole, described as “quite sizeable,” has been discovered close to Shardeloes Lake near Amersham and has been cordoned off and is situated near a public right of way. An email sent by Align informed local residents that the sinkhole measures approximately six meters in diameter and five meters in depth and affirmed that “The landowners have been alerted, and their livestock has been swiftly relocated to ensure their safety.”

The sinkhole emerged in close proximity to a completed section of the HS2 tunnel, however, the tunneling operation was permitted to continue. The gravity of the situation prompted HS2 to involve the Environment Agency and initiate dialogue with the landowner, signaling the seriousness of the matter.

This sinkhole occurrence marks yet another setback in the already controversial HS2 construction endeavors. Previous incidents involving mysterious “bubbling pools” between February and April, along with complications in Ruislip, have hurt the project. The Birmingham to Crewe section of the track has suffered delays, while the costs of the ambitious undertaking are skyrocketing in the tens of billions of public money.

Sinkhole relative to the size of a man

In response to the sinkhole, Paul Jennings of the River Chess Association, an organization dedicated to monitoring HS2’s activities and advocating for clean water, has taken action. Jennings proactively reached out to the Environment Agency, urging an immediate halt to any further work until a thorough investigation can be conducted. Acknowledging the potential impacts, he also requested Thames Water to suspend the water supply to HS2 in the affected area until the matter is resolved.

Jennings stated that over the past ten years, they have consistently alerted HS2 to the inevitable consequences of tunneling through unstable chalk. Tunneling through chalk presents significant challenges due to its susceptibility to collapse and fragmentation. Careful design of grouting and support systems during excavation is imperative to mitigate the risk of collapse.

The leader of Buckinghamshire Council said there have been warnings for years that something like this could happen.

“We’ve been warning for the best part of twelve years,” said Councillor Martin Tett.

As images of the sinkhole circulated on social media, a wave of suspicion washed over anti-HS2 campaigners who wasted no time in directing their messages to HS2 on Twitter, bluntly urging them to cease their digging activities.

Responding to the mounting concerns, an HS2 spokesperson acknowledged the situation, referring to the sinkhole as a “small area of ground movement” situated above the Chiltern tunnels. While investigations are still underway, the spokesperson attributed the occurrence to pre-existing ground conditions. They assured the public that the site has been sealed off and posed no imminent danger to the community, however, doubts linger in the air, fueling suspicions about the true cause of the sinkhole.

Whilst HS2 or Align have not received any direct blame for the sinkhole, investigations are ongoing to determine its origin. Engineers and builders must embrace accountability when their work deviates from the intended outcome, recognizing the importance of learning from failures and taking responsibility for the consequences, in order to drive continuous improvement and ensure the highest standards of quality and safety.

Digging tunnels in stable soil is of paramount importance to avoid the occurrence of sinkholes. Sinkholes are formed when the ground collapses or subsides due to various factors, such as unstable geological formations, water erosion, or human activities.

Conducting a comprehensive assessment of the ground conditions helps in understanding the geological features, potential hazards, and stability of the surrounding terrain. This knowledge allows engineers and planners to design and implement appropriate measures to mitigate risks and ensure the structural integrity of the tunnel. By gaining insights into the ground conditions, including soil composition, water tables, and potential geological faults, potential dangers can be identified and addressed before construction begins. This proactive approach helps to safeguard the lives of civilians and enhances the overall safety of the tunneling project in densely populated areas.

One effective method for assessing preexisting ground conditions at a site is by utilizing the underground mapping feature provided by civils.ai. This advanced technology offers valuable insights into the subsurface environment, enabling engineers and planners to make informed decisions during the tunneling process. By leveraging civils.ai’s underground mapping feature, users gain access to comprehensive data on geological characteristics and soil composition. The mapping feature utilizes detailed 3D models of the subsurface which enables accurate identification of potential risks that could affect the safety and feasibility of tunnel construction. The use of civils.ai’s underground mapping feature enhances the efficiency and effectiveness of preconstruction surveys, ensuring a thorough understanding of the ground conditions and promoting the successful and safe execution of tunneling projects in areas where lives are at risk.