As part of the enabling works to prepare a disused quarry for a residential development scheme, CAN were asked to provide a design and build solution to stabilise four quarried faces around the border of the development. A site inspection and detailed design was undertaken on behalf of CAN by RSK, in order to develop a scope of remedial works. This identified the need for a number of different solutions to stabilise different areas of the high fractured sandstone faces.
In all areas scaling was specified to remove loose rock, and extensive heavy scaling and block removal was then undertaken using excavators and breakers to remove the worst of the unstable blocks in targeted areas. Rock bolts were then drilled, utilising excavator mounted drill rigs, to secure individual blocks that remained attached the face but with potential to come free in future. Areas of passive rockfall netting were also installed in sections where there was deemed a risk of minor rock fall from the face as it weathers in future, and sand-cement bag dentition was constructed to support undercut voids.
One of the key goals was to minimise the aesthetic impact of the finished stabilised faces, and to help with this rock mesh that more easily blends into the face was utilised, along with epoxy painting the rock bolt heads plates to blend in better with the sandstone rock. Resin was chosen to bond the bolts to speed up curing time and help achieved an ambitious 9-week programme, and works were completed ahead of programme including several elements of additional works instructed once on site – this included further areas of active rock netting, additional heavy scaling and removal of graffiti from some of the rock faces.
Duration: 2 months
Client: Sirius Remediation