A.G.A Group Bioengineering Practices- Case Studies

Case Study - Cirencester Town Council

Bank reclamation and floating island installation

Project: Erosion protection and habitat provision
Products: Pre-planted coir rolls and pallets, Floating islands

Problem
Along this section of the River Churn, a tributary to the River Thames, bank-side erosion has become a serious problem and the river was becoming over widened. This was due to a number of reasons, primarily that the banks were made of unconsolidated material and with little protection were susceptible to erosion.

Solution
The solution put forward by the A.G.A Group involved reclaiming sections of the bank from the river and using excess silt from the river to backfill behind newly constructed revetments. The robust erosion protection was provided by pre-planted coir rolls situated on faggots. This in effect created a new bank behind which the silt could be positioned thus deepening this stretch of the river.

The first stage of the project involved constructing the revetments behind which the silt could be placed. These revetments were positioned approximately 2m out from the existing banks. To gain the desired elevation of the pre-planted coir rolls faggots were positioned underneath, not only providing the elevation but further protecting the bank from erosion.

Once the revetments were constructed the silt could be positioned behind. On to this the pre-planted coir pallets were positioned which over a short time period have now fully established and developed. The reclaimed sections of bank now provide excellent habitat both above and below the water line.

The floating islands offer numerous benefits including important refuge for fish from predators The floating island were then positioned in the middle of the river. Floating islands provide a number of beneficial services including to further protect against bank erosion. The islands also help to balance the ecology of the river, taking up excess nutrients and providing spawning habitat and refuge for fish.

This bioengineered solution has proved extremely successful in achieving the aims of the project and providing a ‘green’ solution whereas in the past hard erosion measures may have been used. By using bio-engineering techniques such as this not only are the aesthetics of a site improved but provision is made for habitat that encourages biodiversity both above and below the waterline.

For more information on any of the A.G.A Bio-engineering products, why not call one of our trained advisors on:
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Last Updated ( Thursday, 24 April 2008 12:33 )