Mainmark Completes Godstone Sinkhole Repairs

Overview of the Godstone Sinkhole Incident

In February 2023, a sinkhole measuring 20 metres long, 5 metres wide, and 5 metres deep opened on Godstone High Street in Surrey, revealing historic sand mine workings approximately 8 metres below the surface. The incident was initially classified as a major incident, but has since been downgraded to a significant incident. This change reflects the progress made in addressing the situation, which began with emergency work on February 18.

Repair Efforts and Ground Improvement Programme

Mainmark, a leader in ground engineering solutions, completed a three-week ground improvement programme aimed at stabilising the area. This programme followed an extensive 18-month repair effort, during which the company installed around 600 resin injection points across High Street and Salisbury Road, targeting depths between 1 to 4 metres. The primary goal of these works was to prevent void migration pathways above the remediated mine network, ensuring safety before full road reconstruction could take place.

Impact on Local Residents and Infrastructure

As a result of the sinkhole, around 30 properties were evacuated, with some residents allowed to return home as of the weekend following the completion of Mainmark's work. Water supplies to the wider area have been restored, although road closures and diversions remain in effect, particularly affecting the A25. Local bus services, including Metrobus routes 400, 409, and 410, have also been rerouted due to the ongoing repairs.

Future Considerations for Transport Authorities

The incident has prompted transport authorities in the UK to reassess their strategies regarding drainage and slope stability, especially in light of record heat experienced this summer and warnings of a strong El Niño. This situation has led to a shift towards higher-capacity culverts and reinforced earthworks to better protect critical transport assets. Mainmark's work in Godstone is indicative of a broader trend, as the company has previously employed similar resin injection techniques at Tottenham Hale station for Network Rail.

Conclusion

The successful completion of the ground improvement programme by Mainmark not only addresses the immediate concerns raised by the Godstone sinkhole but also sets a precedent for future infrastructure resilience in the face of environmental challenges. As local authorities continue to evaluate and enhance their infrastructure, the lessons learned from this incident will undoubtedly play a crucial role in shaping future repairs and preventative measures.