12 METRE EMBANKMENT THE LARGEST STRUCTURE OF ITS TYPE IN IRELAND
Moy Park Hatchery on Main Street, Donaghmore in County Tyrone is part of a multi-million pound business supplying convenience foods to supermarkets across Europe. Built in rural surroundings on land sloping down to a river, an innovative land reclamation solution was required to create the additional space required for an extension to the existing car and lorry park.
The solution was provided by Maccaferri, specialists in retaining structures, soil reinforcement and erosion protection. The company’s Green Terramesh® has been used to construct a 12 metre high reinforced soil retaining wall, stabilising the slope and enabling the construction of an extension to the car and lorry park at the existing level.
Green Terramesh was specified for the project by architects McKeown & Shields of Coalisland, County Tyrone. With the river bed just six metres from the foot of the projected embankment and with the requirement to raise existing soil levels by at least eight metres, a feasibility study was undertaken to determine the best method of construction.
The existence of peat and soft clays meant that the ground conditions were unsuitable for the construction of a reinforced concrete retaining wall, unless extensive piling was undertaken. As a better alternative, the architects specified a reinforced soil solution, which could be installed without extensive ground preparation.
A significant cost advantage arose because Maccaferri’s solution involved the re-use of site-won materials, avoiding the need for costly removal of excavated spoil and the importing of stone or blocks.
This solution also has aesthetic benefits. Moy Park Hatchery is located in a rural environment, with the proposed retaining wall overlooking a residential area. A grassed slope is visually much more attractive than a concrete structure.
Installed by main contractors, Geda Construction from Dungannon, County Tyrone, the Green Terramesh bank has already ‘greened up’, a layer of biodegradable coir geotextile behind the front face, retaining sufficient topsoil to allow for rapid grass seeding.
Suitable for reinforced soil slopes of up to 70%, each unit of Green Terramesh is 600mm high. Formed from a single sheet of hexagonal, double-twist woven steel mesh, when installed, Green Terramesh is formed into three sections, a horizontal soil reinforcement tail, a facing section and a horizontal return top section. Triangular support brackets behind the front face provide added rigidity and allow easy installation of the grid by eliminating the need for temporary formwork.
Installing Green Terramesh is quick and easy, with bracing triangles ensuring accurate installation. Units are either laced or can be fixed together with special rings dispensed using a Spenax pneumatic tool, available from Maccaferri Ltd.
The UK arm of the Maccaferri Industrial Group, headquartered in Italy, Maccaferri Ltd specialises in gabions, geotextiles, geogrids and geomats. In addition to a full range of products for retaining structures, soil reinforcement and erosion protection, the company offers an in-house construct, design and consultancy service.