The ground collapse on Godstone High Street in February 2025 opened a hole 20m long, 5m wide and 5m deep. While initially linked to sandstone erosion caused by a burst water main, investigations revealed further complex challenges: an underground mine network eight metres below the village, requiring extensive ground strengthening before the road could be reconstructed.
Mainmark worked as part of a multidisciplinary team appointed by Surrey County Council, carrying out resin injection works to strengthen weak and disturbed ground beneath the affected roads.
Following remediation of the deeper mine workings by the wider project team, Mainmark carried out targeted resin injection between one and four metres below ground level to strengthen weakened and disturbed ground and address potential pathways for future void migration. Mainmark installed approximately 600 resin injection points across High Street and Salisbury Road during the three-week programme of ground improvement works.
David Hedley, infrastructure lead at Mainmark UK, said: “Ground collapse events rarely have a straightforward cause. While damaged utilities can contribute to the formation of underground voids, investigations at Godstone also identified historic sand mine workings beneath the site, creating a more complex remediation challenge that required multiple ground engineering techniques.”
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