In April 2018 a substantial slope failure occurred on land bordering the back gardens of residential properties in Dorking, Surrey. The slip resulted in undermining of residents’ gardens, with fencing and parts of the gardens themselves being lost.
Following a minor regrade of the slope by an earthwork’s contractor, CAN Geotechnical Ltd was contracted to carry out remedial works to stabilise the slope and prepare for reinstatement of the property’s gardens.
Campbell Reith designed the slope stabilisation solution which called for 147no. hollow bar soil nails to be installed to a depth of up to 14m, with the slope then overlain with 700m2 of steel wire mesh and erosion control matting.
A total of 19no. inclined drains were installed up to 18m into the slope, and linked in to a surface drainage system consisting of interceptor drains running across the slope and a vertical mid slope drain. This allowed groundwater to drain freely and avoid over-saturation in future. Finally, 22no. vertical mini piles were installed along the mid-slope and crest to facilitate the construction of a decking, allowing the residents gardens to be extended back to the property boundary.
CAN carried out the works using compact plant and a slope mounted drill system suspended from a temporary crest access system within the garden. This allowed the works to be undertaken despite the highly restricted access. The works were completed safely, on time and within budget.
Duration: 12 weeks
Client: Campbell Reith Consulting Engineers
Location: North Holmwood, Dorking