Following the collapse of a mine shaft in the road and ground subsidence in a private garden, Frederick Sherrell Ltd were asked to investigate the extent of old mine workings affecting a housing estate in West Devon. The research of old mine plans and other historical records indicated that the housing estate was built over a disused 19th century copper mine. The records indicated that other shallow mine workings existed but their condition was not known. A phased ground investigation was carried out. Initially a geophysical survey was undertaken using several different methods (microgravity, ground penetrating radar and magnetometry). This highlighted several areas of concern that we subsequently targeted with a drilling investigation.
The ground investigation confirmed the presence of shallow mine workings and uncapped mine shafts beneath roads, gardens and several houses. A programme of remedial emergency works was carried out including capping mine shafts and lode outcrop zones, backfilling shallow tunnels and installing geogrids.