Autumn 2013

Durable

TenCate Geotube® technology for restoration of spit of land

TenCate Geotube® technology was used for the restoration and reinforcement of a spit of land in Norfolk (UK) between the River Bure and a peat bog. The work itself had minimal impact on the environment. The project received an honourable mention from the Canal & River Trust.

Salhouse Broad is a lake to the north-east of Norwich (Norfolk, UK). It formed as a result of the extraction of peat. The spit of land between this lake and the River Bure has been severely affected by erosion in the past sixty years. If this watershed were to collapse, river water would flow directly into the lake and cause great damage to the landscape, which is an important habitat for wildlife. The spit of land thus had to be restored and reinforced. At the same time it was decided to restore a former reed bed. 

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The floor of Salhouse Broad (picture: Mike Page) is covered with an approximately five-metre thick, soft layer of sediment, which means hat traditional methods to establish a solid structure are not adequate. TenCate Geotube® containers filled with local dredging material, however, are. Four huge TenCate Geotube® units measuring 8.5 metres wide were filled with about 3,000 m³ of sediment, dredged out of the Bure. This was used to form a 170-metre-long retaining wall. Some 9,000 m³ of dredgings were deposited behind the containers in order to restore the 7,000 m² reed bed and to bring the waterline back to its original state.  

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Picture: Mike Page

With an eye to stability, erosion protection and the fauna, the dredgings in the TenCate Geotube® containers were planted with reeds and grasses. This is vegetation that is very common here and is thus expected to catch on quickly. Once the reed bed has been completely restored, it is expected to attract a variety of animal species – and, of course, more tourists.

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Picture: Mike Page

This restoration was part of the European PRISMA project. It was set up to develop innovative solutions for dredging, treating and reusing sediment from waterways. The Broads Authority worked closely with the experts from TenCate and the Dutch engineers from Besekk. During the ceremony for the 2013 Water Renaissance Awards in Birmingham (UK) held on 23 May, under the auspices of the Canal & River Trust, the Salhouse Broad project received an honourable mention in the Innovation category.  www.tencategeosynthetics.com geosynthetics.europe@tencate.com   Through the application of TenCate Geotube®, the vulnerable spit of land between river and lake has been restored and strengthened, and the new land will be soon covered with reed and sedge vegetation.

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