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Case Study: Purton Weir

Project Type:               Erosion Repair
Project Location:        Purton, South Gloucestershire
River System:              Sharpness Canal
Client:                            British Waterways May Gurney 
Date of Installation:    November/December 2009

 
 

Project video:
 

   
 

Click above to play the video detailing the various stages of construction (requires sound)

 

 The Problem:

A disused sluice on the Sharpness Canal was recently re-commissioned and modernised to release excess water into the adjacent Severn Estuary.
 
When the new sluice was first activated during the summer floods of 2007, the force of the discharge  eroded the adjacent SSSI foreshore and exposed the original Victorian spillway.

In addition to deteriorating stonework from the original structure, saturation of the cliffing face resulted in bank collapse and the loss
of designated land following each tidal exchange.
The rapid rate of bank retreat meant that the works had to be designed and implemented within a very  tight time frame.
 
 
The Solution:

Cain Bio-Engineering Ltd (CBE) was contracted as principle designer to repair and protect the Victorian spillway and surrounding environment.

CBE was then sub-contracted by British Waterways May Gurney to install the bio-engineering elements of the repair including a Coirnet terraced revetment and brushwood sediment trap.

A rock ramp attenuator was also installed at the Apron ‘toe’ to prevent further loss of material from the spillway.


The fact that the Severn estuary has the second highest tidal range in the world placed further restrictions on the working day. Cain Bio’s Ops team was awarded the design/build contract and our operatives worked seven days a week for five weeks to complete the project on schedule.

The completed project is designed to naturally accrete with water-borne sediment and was left unplanted to allow the new sloping terraces to colonised naturally with local species.

The attached video details the various stages of construction.