CAN Geotechnical, an RSK company, has been awarded a contract to undertake geotechnical stabilisation work at the historic Fort Bovisand in Devon, UK. CAN will bring both its specialist access capability and drilling expertise to the redevelopment of the 170-year-old Victorian fort. This heritage structure at Wembury is being turned into 81 apartments by Fort Bovisand Developments Ltd, which is owned by former BBC Director General Greg Dyke. The development will also include an events space, a bistro and a visitors’ centre.
Fort Bovisand in Wembury, UK, requires stabilisation work ahead of redevelopment
Before redevelopment work on the site can begin, some specialist slope stabilisation work is required. The critical first element in the overall project will be stabilising two gullies immediately beneath the access road that runs along the top of coastal cliff faces leading into the Fort complex; each location requires specialist equipment and work-at-height experience. The project’s geotechnical designer, Red Rock Geoscience Ltd, has specified a soil-nail and facing solution for stabilising the gullies and preventing further erosion from undermining the access road.
The eastern gulley will have 195 R32 stainless-steel soil nails installed in a grid pattern over the cliff face and the western gulley will need 127 of the same type of soil nail; both gullies will be faced with steel netting and erosion matting.
CAN’s approach is to use an excavator-mounted hydraulic drill rig to install the upper bolts of the netting system and to drill the rows of soil nails in the face of the crest.
Temporary anchors will then be installed and used to suspend CAN’s in-house-designed ‘A-Frame’ cliff-mounted drill rigs. These A-frames enable the drill crews to use winches to move the rigs to each soil-nail location on the cliff face and access them by abseiling down and working suspended from ropes to undertake the drilling.
On completion of CAN’s works, a marine contractor will install a rock protection system at the base of the cliffs to protect them from future wave action and will repair a shoreline defensive wall. The combined stabilisation measures will enable the current temporary weight limit to be removed from the access road, thus facilitating the main redevelopment works to begin with safe, unrestricted access to site.