The shafts and adits that provided entry to the abandoned mineworkings represent a problem in their own right.

By definition they must have come to the surface though this location could be remote from the workings themselves or the workings could be deep enough not to require treatment themselves.

Subject to the proposed development, mineshafts can be treated by grouting over their whole depth over a short depth below bedrock and/or many have a reinforced concrete slab constructed across the opening.

The consolidation process initially defines the size and orientation of the shaft. Then using a safety platform a series of individual small diameter boreholes are drilled into the shaft to the agreed treatment depth and injected with cement : pfa : sand grouts as the drilling lance is retracted.

A concrete slab when required would usually be constructed at rockhead or on a competent strata. This necessitates an excavation prior to placement of any formwork, reinforcement and concrete with the excavation backfilled with appropriate compaction techniques on completion.