en.Wedoany.com Reported - Repair work on Goldstone High Street in Surrey, UK, triggered by a ground collapse in February 2025, was completed on July 8, and the road is expected to reopen by the end of July after SES Water completes pipeline upgrades. Following the completion of resurfacing work in early July, Surrey County Council finished the main repair works on the collapsed section.
On February 17, 2025, a ground collapse occurred on this section, forming a pit approximately 20 meters long, 5 meters wide, and 5 meters deep. Initial assessments linked the collapse to the erosion of sandstone bedrock caused by a burst water pipe, but subsequent investigations revealed a network of 19th-century sand mine tunnels 8 meters below the collapsed area, complicating repairs and delaying the road's reopening. The council's highways team completed grouting and filling of all mine areas by April 2026.
A spokesperson for Surrey County Council told GE that approximately 1,100 tonnes of grouting material were used to fill and stabilize the mine voids. Methods included bulk filling of remaining tunnels through boreholes (drilled 8 to 10 meters below ground) and compaction grouting to reinforce the foundation beneath the collapse zone. Compaction grouting was carried out to the specifications of consulting engineers, involving the application of pressure to the grouting material to achieve consolidation of the surrounding ground, with secondary and tertiary treatments at progressively reduced grid spacings to confirm effectiveness. Finally, resin injection was performed at depths of 1 to 4 meters below ground to mitigate the risk of residual voids migrating to the surface. To ensure foundation stability, the engineering team used downhole cameras to verify the extent of bulk filling and conducted cone penetration tests and plate load tests at subgrade level to confirm the foundation could withstand traffic loads.
The project team was advised by Stantec. Ringway Infrastructure Services, as the council's term maintenance provider and principal contractor, led the construction; Forkers undertook specialist foundation repair works; Mainmark carried out resin injection; and CJ Thorne provided civil engineering services. After the main works were completed, the site was handed over to SES Water for repair of the damaged water pipe.
Surrey County Council stated that, due to the focus on repairing and reopening the road, the root cause and sequence of events leading to the ground collapse cannot yet be definitively determined. According to the BBC, repair costs had risen to £2.3 million earlier this year and are expected to potentially exceed £3 million.
