Looe Retaining Wall Design - Structural Remediation

Located in the southeast of Cornwall, is the coastal village of Looe. A concrete wall, dating from the 1950s some 600m long and up to 3.5m and supporting Elm Tree Road, collapsed following work on the downhill side to create a garden at the base of the wall and heavy rainfall.

Our first action was to undertake emergency safety stabilisation and to assess the safety of the adjoining 8 properties. We then reduced levels within the “crater” by benching the slope and installed soil nail restraint to provide a safe working strip of about 3m from which the collapse debris could be removed and new foundations of 220mm diameter piles could be installed to support a ground anchor tied support slab for pre-cast concrete retaining wall elements. On completion, a new road surface and vehicle safety barriers were provided.

The retaining wall required complete structural renovation. Our engineer designed a reinforced concrete wall with ground anchors to provide a stable structure with a minimum design life of 75 years. To maintain good line and to ensure that permanent works were provided on the land of the owner responsible. For these remedial works, a steel wire or “string line” was installed. Where parts of the original wall did not collapse but were only slightly distorted, a series of ground anchors were installed to reinstate the wall stability for the long term.