COMFORT LEVELS for horseshoe bats are getting high priority in the ongoing stabilisation of the Combe Down Stone Mines south east of Bath.
Working for Bath and North East Somerset Council, Bristolbased Hydrock Contracting is carrying out emergency works in the mines.
This involves excavating fallen stone blocks and driving roadways through the mines together with pumping foam concrete, spraying shotcrete and pneumatically placing stone to stabilise high hazard areas before the main stabilisation contract begins.
With no off-the-shelf tunnelling machine small enough to work in the available space, Hydrock engineers have designed and built a special rig.
In addition to the challenges created by the environment, the mines are an important hibernation site for horseshoe bats and are a site of special scientific interest.
Noise and light levels have to be carefully monitored and certain areas have restricted access.
Unannounced visits from a bat specialist appointed by the council ensure that conditions are met - failure to comply could result in suspension of works.
The stone mines were historically the source of Bath Stone - an oolitic limestone - and have been mined since the 15th century. During storms in 1987 a tree fell into the mines. Bath & North East Somerset Council commissioned consultant Parson Brinckerhoff to investigate and develop a solution.
Hydrock's contract is expected to last six months, It will also carry out the main stabilisation, scheduled to begin in 2004.
The project is being funded through the government's Land Stabilisation Programme run by English Partnerships at an anticipated cost of more than £30m.