River Brede – Geotechnical bank stabilisation

The rapidly eroding bank was stabilised and reinstated with a two tier coirnet revetment

Project Brief

During the unusually wet winter of 2019-20, the excess of flood water being discharged down the River Brede caused a substantial erosion and collapse to the riverbank garden frontage of a private property near Winchelsea. The total slumpage equated to almost a third of the garden area, and required immediate attention in order to stop any further bank failure which may have encroached on the foundations of the house. Cain Bio-Engineering were asked to design and build a suitable bio-engineered erosion control solution for this section of river bank

Solution

The erosion control solution designed and installed by Cain Bio-Engineering consisted of reinstating the original toe of the bank by constructing a 30m long lower tier coirnet revetment. This then in turn supporting a 6m long second tier coirnet revetment, which was required to stabilise the lawn area. The use of two ply geotextiles and imported gravel back-fill make the structure resistant to erosion. The planting of willow whips to the front face of the lower tier revetment, will provide further stability as root structures begin to establish over time. The end result was a successfully reinstated river bank and amenity which is resistant to erosion.

Before

Arial view of bank slumpage and erosion
Slumped private garden frontage, nr Winchelsea on the River Brede.
Detailed view of bank failure
Evidence of the extent of the geotechnical slip circle and garden loss.

During

Long reach excavator use for construction of erosion control
Installation of the coirnet revetment using a 22m long-reach excavator for access.
Construction of river bank erosion control
Placement of Willow whips to the lower tier coinet revetment during construction.

After

Completed two tier Coirnet revetment erosion control
Completed two tier coirnet revetment.
Completed two tier Coirnet revetment erosion control
Detailed view of the 2 tier revetment and the newly reinstated lawn area.

“Many thanks to everyone for doing such a fantastic job. Your men working on the construction were extremely helpful and professional. Thanks to Jeremy and team for producing exactly what I wanted – and more so!!”

– Client