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Bioengineering – the use of vegetation and natural/man made materials in Civil Engineering construction for surface soil protection, slope stabilisation,

watercourse and shoreline protection

Richard Edwards

Typical Issues and Problems

• Incorrect choice of product/solution (Willow spiling/soil filled geotextiles)• Concept that bioengineering is always a soft solution (Hard/soft combine)• Bioengineering can only be used in low energy rivers (Not true)• No performance data with bioengineering materials (There is!)• Long term performance • Maintenance issues (standard get out clause even within the EA)• Not involved till it’s too late (ECI vital)• General civil contractors used on frameworks rather than specialists

Bioengineering correct choice

Soil erosion control and habitat creation

• Challenge soft and hard engineering

• Study failures. Why?

• Right technique for problem

• Undermines confidence

• Once bitten twice shy....

Replacing four tiers of blockstone

Bioengineering can be a combination of hard and soft.

Mobile Gravel/Cobble Bed

1. Cobble Bed 2. Degradation/Bed

Down cutting 3. Shading 4. Very Steep/High

Energy 5. Blockstone

Proposed

Bioengineering Solution

Bioengineering Solution

BioEngineering Solution

6 weeks on

Slopes Cut & Prepared in Colliery ShaleGrass & Legume Mix Sown

Case study 2 River Ebbw – High Energy Blockstone Replacement

High Performance Composite-TRM installedNAG P550 over prepared surface

High Performance C-TRM with Rock Roll & Willow Fascine ToeLive Willow and rock roll toe revetment

Completed Installation Completed Installation

4 m/s flood!One flood event onto unprotected slopes

Blockstone v bioengineeringOne year later.

Blockstone v bioengineeringFive years later.

Blockstone v bioengineeringFive years later....