An ambitious £4m retail and infrastructure redevelopment project to build a 22m high plateau based on the sustainable re-use of colliery waste in a South Wales valley is believed to be the highest structure ever to be built from colliery spoil in Europe.
The project has employed Tensartech earth retaining technology from Tensar International at the former mining town of Bargoed in the Rhymney Valley, to construct the 3 ha plateau for new shops and amenities, saving material and transport costs as well as recycling unsightly waste. Contractor HOCHTIEF / Griffiths Joint Venture (JV) is now completing the second phase of the project on behalf of Caerphilly County Borough Council (CCBC).
As part of a long term £30m plus Community regeneration project, CCBC is transforming the valley below the former coal mining town of Bargoed with new highways, including a 200m cross valley viaduct spanning the river and railway, providing access to the river and the retail plateau. The scheme has been designed and supervised by Capita Symonds, and has a number of major regeneration objectives including the integration of public transport.
The creation of a new bus station adjacent to the existing railway station has been further enhanced by the construction of a park and ride facility. This has been constructed to the same specification as the main plateau creating a valuable facility where only an embankment existed previously.
About 120,000m3 of fill was required to build up the plateau to the height of the existing town. Rather than import expensive granular fill, Tensar proposed its value-engineered Tensartech GreenSlope solution which would re-use the abundant local colliery spoil and finish the 60˚ slopes with a vegetated face.
The plateau’s reinforced slopes were constructed around a core of engineered colliery spoil, by using Tensar uniaxial geogrids between 10 to 20 metres long, layered with compacted spoil and secured to the specially-angled steel mesh units at the outer face.
The facing was lined with biodegradable matting placed inside the mesh units to retain a layer of seeded topsoil to create a 60˚ grassed slope; with over 4000m2 of grassed slopes, the appearance of the valley will be transformed. The design also incorporates a footway link, which utilises one of the berms and climbs up the face of the plateau; the use of the green slope facing has made the creation of this feature far more in keeping with the adjacent Bargoed Country Park.
Around the top edge of the slope, a Tensartech TR2 Wall system, with a vertical steel mesh face lined by a local stone cladding, was used to build a crest wall. The designers have set out to create a unified appearance fore the whole project.
The Greater Bargoed Community Regeneration Project is part of CCBC’s strategic 10 year plan (based on a study by Camlin Lonsdale 2005) to transform the town and neighbouring communities.
As a result of the improved transport links with new rail, bus and road infrastructure projects, as well as the planned retail developments, the scheme will attract new employment investment into the area.
The Department for the Economy and Transport is providing £31m of funding for the overall project including over £24 for the highway and reclamation works. More than £3m is also being provided by other public and private partnerships, including the Heads of the Valleys Programme and Caerphilly County Borough Council.
For copies of Tensar International’s Tensartech GreenSlope and Tensar Structural Solutions brochures, please visit www.tensar.co.uk.
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