RSK’s geotechnical engineering specialist, CAN Geotechnical, has been awarded a £2 million contract as part of a £2.5 million programme to undertake slope stabilisation and improvement work at Canford Cliffs in Poole, UK.
Following a landslip to a section of the sea cliff below the Cliff Drive area in 2017, the ground has been closely monitored and investigated by Bournemouth, Christchurch and Poole Council – including the Poole Cliffs Site of Nature Conservation Interest (SNCI), part of which is in the area under consideration. A risk of further instability was identified and, in July 2020, CAN Geotechnical was appointed to undertake the essential cliff-stabilisation work.
CAN will start work on site in September and will stabilise the 30-metre-high, 200-metre-long section of the cliff over a nine-month period. This will involve drilling over 1600 steel soil nails (with additional epoxy paint corrosion protection) up to 15-metres deep into the cliff face, along with more than 50 drains drilled into the slope. A high-tensile stainless steel netting and erosion control matting system will then be installed over the entire slope.
In the 1970s, a novel ‘transverse beam’ stabilisation system was installed; this resembles a rope ladder draped over the cliff to retain the loose soil on the surface, and an important part of the work will be to remove this expired structure. Further challenges relating to the site include the ecological element and local wildlife, as well as minimising any public disruption. Reptile relocation is already under way to remove protected slow-worms from the site. Works will be undertaken by CAN with strict environmental controls to ensure the SNCI area is maintained and protection given to important species such as sand lizards and Dartford warblers.
As the project is in a popular tourist and residential area, CAN will also ensure the works fit with the site footprint, and measures will be employed to minimise disruption. These will range from minimising the visual impact of the work to controlling the noise and vibration throughout the area. A programme of community briefings and engagement events for residents is planned.
Speaking about the project, CAN’s Business Development Director, Ben Foulger, said: “Further to the work to safely and permanently stabilise the landslip-prone cliff face in this regionally important area, CAN will also be undertaking preparation work for later stages of the scheme, such as the installation of new electricity and water service routes down the cliff. This will facilitate further seafront improvements planned by Bournemouth, Christchurch and Poole Council.”