Following the establishment of a new Government fund Bath and North East Somerset Council was able to initiate a major engineering project that pushed technical boundaries to new limits, was at its peak the largest mass foam concrete infill project in the world and had the largest mine shift in England.
Deterioration of mines over the centuries
The condition of the mines had deteriorated since their closure in the mid-19th century, with no maintenance work taking place to secure the mine roof. The mine survey plan undertaken in the 1990s to ascertain as much information about the workings as possible showed a large number of mine roof collapses had occurred since the mine had closed, and the majority of the original timber support had rotted away. The highly fractured roof had been allowed to sag, increasing the risk of further roof falls. A number of pillars had become over stressed due to the high extraction ratio and were effectively providing minimal support to the roof. It was seen as only a matter of time before significant pillar failure occurred leading to widespread surface subsidence.