Rock face scaling and stabilisation, Jersey
Before a residential development could be undertaken at the base of the former L’ Etacq quarry, work had to be undertaken to stabilise and strengthen an adjacent rock face. Joint fractures in the face of the steep granite bedrock, up to 35m high in places, had been causing rock falls which had to be prevented. Due to restricted access, all work had to be carried out by abseiling operatives qualified to IRATA level 3 and 1.
Initial work involved the cutting down of trees growing close to the top of the cliff edge followed by the removal of vegetation and loose material on the rock face using hand tools. Rock excavation was also required to remove large overhanging slabs of rock and scaling of the face, with careful control of debris falling to the base.
To secure the face abseilers, using hand-held rock drills, installed 300 linear metres of rock anchors and then secured some 700m2 of surface rockfall netting to the face using wire ropes and fully grouted steel dowels, up to 3m long. In total over 1500m² of rock face was strengthened and secured to prevent any further rock falls and enable the housing development to proceed.
Technical Details:
- Stabilising 1,500m² of 35m high rock face using abseiling techniques
- Removal of nearby trees, loose rock and vegetation
- Scaling of rock face and removal of overhanging slabs
- Hand-held drilling into dense granite bedrock
- Installation of 300 l.m. of rock anchors
- Securing 700m² of rockfall netting using grouted dowels and wire ropes
