Built within what was formerly a chalk quarry which supplied the raw materials for a nearby cement factory, the 20 hectare site needed major embankment stabilisation work before house-building work could begin.

 

Contractors C A Blackwell called in geotechnical specialists Maccaferri for help in the stabilisation of a 20m high embankment of crumbling chalky soil next to the main entrance to the 400 dwelling site.

 

The Maccaferri solution involved the installation of their innovative “Armater” Cellular soil containment system. Looking like a giant concertina of interlocking 500mm diameter hexagons, the Armater creates a grid of 100mm deep pockets that hold topsoil. When seeded, root growth binds the soil layer together and to the underlying materials, preventing it from slumping down the steeply sloping site and giving a more aesthetically pleasing “green” aspect.

 

Armater is a polypropylene, non-woven geocomposite material, manufactured in easy to handle packs which, when unfolded and opened out on site, creates an interlocking network of honeycomb shaped soil pockets which are open at the top and base. Each pack expands to 80 sq m and retains seeded topsoil and promotes vegetative growth on slopes up to 65 degrees.

 

Armater can be used with reinforcement such as soil nails or geogrids when slopes are structurally unstable and require more than surface support.

 

Installed by CAN Geotechnical, their specialist engineers used rock climbing skills to abseil down the slope to fix the 600mm long, high tensile steel pins that hold the Armater System in place.

 

In other areas required which required greater tensile strength, CAN used Maccaferri’s MacMat-R reinforced soil containment and retention matting as an erosion prevention measure. The steel mesh- reinforced, polymer fibre, 3-D matrix system was pinned to the 30 degree slope using 2m long high yield locating bars. Imported topsoil, which was then hydro seeded to bear grass, gives the area a softer landscaped aspect, more in keeping with the surrounding countryside.

 

The Maccaferri Armater installation was part of a £2m groundworks programme for the Medway Gate Development. Maccaferri also supplied its Green Terramesh, reinforced earth retaining wall system for a 170m x 25m high buttress wall and 3000 sq m of its rockfall netting for steeper areas of redundant quarry face within the site.

 

Maccaferri Ltd is the UK subsidiary of the worldwide Maccaferri Industrial Group which has its headquarters in Bologna, Italy and manufacturing facilities in over 20 countries, worldwide.

 

Traditionally known for the production of wire mesh “gabions” – used for erosion protection and slope reinforcement in rail, road and waterway applications, Maccaferri has expanded significantly over recent years and now operates over a wide range of geotechnical and civil engineering disciplines.