Mass Gravity Retaining Walls
2021
Blackburn, Lancashire
Countryside Properties
Countryside Properties
Williams Walling Ltd
VALUE ENGINEERED WALLS FOR HOUSING SITE
Finished gabion wall stretching along the line of properties
Finished Gabion wall
Gabion wall under construction
Problem
A plot of land in Queen Victoria St, Blackburn was developed by Countryside Properties. The sloping site required a retaining wall along a boundary in order to level the housing plots and increase the development potential. A pre-cast concrete retaining wall had been initially included in the project.
Maccaferri was approached by Countryside to propose value engineering proposals to replace the pre-cast walls.
Solution
For the 200m long and up to 3.5m high structure, Maccaferri proposed a mass gravity gabion wall. This was built with a steep front face to maximise development land and would offer substantial savings over the proposed pre-cast walls.
In some locations, the gabion wall would face an existing road. As such, it would be exposed to winter salt spray and accordingly, a gabion with a 120-year design life under these conditions was required.
Maccaferri designed the gabion retaining structures featuring double-twist mesh woven gabions. These are manufactured from steel wire with zinc-aluminium heavily galvanising and an additional PoliMac coating. This advance in PVC coatings offers a 120-year design life even in aggressive environments backed by BBA Certification. The gabions were filled with hand-placed locally sourced stone to provide a high-quality attractive dry-stone wall-type finish. Plain galvanised gabions would not offer the required design life under these exposure conditions.
Maccaferri gabions have BBA Certification and an EPD Certificate (Environmental Product Declarations – www.environdec.com) which provide transparent third-party assessed declarations on the emissions generated during their manufacture. This enables designers and clients to compare solutions for their on-site issues.