KELLER COMTEC has used the Textomur retaining wall system to create a dock-like sunken garden in Barrier Park, North Woolwich, London.
Textomur reinforced earth retaining walls were developed in Switzerland in the 1980s. The system comprises a sacrificial steel mesh formwork and geosynthetic facing fabric forming up to 70degrees slopes.
Five-metre long sheets of steel mesh - T8 and T10 at Barrier Park - are bent to provide a horizontal mat and face reinforcement at the required angle. The face is backed by geotextile or geogrid-reinforced fill and can be vegetated by either planting or grass seeding.
Barrier Park has a nautical theme, reflecting the shipping heritage of the Thamesside town. A neighbouring residential development looks like an ocean liner with roof terraces extending out and down to the park and the sunken garden.The development was proposed by the now disbanded London Docklands Development Corporation and has since been taken up by English Partnerships.
Comtec was subcontracted by May Gurney to design and build two parallel 100m long walls to form the 4m deep sunken garden designed by French architect Alain Provost.
Comtec completed the £200,000 project in six weeks.
'The architect needed straight lines and steep walls to create the effect and a reliable method capable of achieving a green face was needed to match the outline design, 'says Keller Comtec general manager Jerry Fox. Textomur was chosen because it achieves tight tolerances of less than 1% of the wall's height and can support vegetation at steep angles.
The site was previously home to a range of heavy industry including a tar refinery and chemical works.
Remediation produced substantial quantities of crushed concrete and masonry to be used as fill material.
A 500mm thick layer of the fill was used to provide a foundation for the walls. This was covered with a layer of non-woven TRG 350 reinforcing geotextile. The 70degrees walls were then built up in 0.5m lifts with successive steel mesh and geosynthetic fabric facing units backfilled with 200mm layers of fill.
Shrubs were planted through holes cut in the UVprotected facing fabric and into topsoil, which was placed behind the face before each new layer of fill. An irrigation system to help the shrubs thrive was included in the design.
Fox says the finished walls are robust and can cope with settlement of the fill without face deformation.