 During 1989 a utilities contractor unexpectedly broke through into part of the mine complex whilst excavating a trench, which resulted in Bath City Council commissioning studies to survey the condition of the mines.It was clear that the mines were in very unstable and some experts considered them to be the largest, shallowest and most unstable of their kind in Europe.An underground survey of the Firs and Byfield mine areas was carried out in 1994, commissioned by the then Bath City Council.