FALCON FOUNDATIONS recently completed a 2.5m high and 35m long reinforced concrete retaining wall to prevent collapse of a brick wall behind a residential block in north London.
Parts of the wall had moved 125mm since March 1999, giving an lean of over 425mm in places.
The original plan to demolish and rebuild it would have potentially increased the risk of partial collapse, but would also have meant extensive excavation of the retained gardens behind Linden Mansions, raising costs.
Falcon Foundations' proposal instead opted for building a new reinforced concrete wall in front of the old. Its plan to prop the structure and build a new retaining wall in stages was agreed by the client and its consultant Arthur Ferryman & Associates.
The most logical and workable access was to strip out a ground floor flat, through which all spoil, plant and materials were manoeuvred, including about 200t of hand dug excavated earth and 5t of rebar carried in by hand.
To form the wall, a total of 70m 3of concrete was pumped 80m from the main road at the front of the building. It was completed in four stages with the temporary propping moved around as work progressed.