Case Study
Wilsford and Great Durnford River Restoration
Location
Salisbury, Wiltshire
Date
September 2016 – November 2016
Client
Working in partnership with AMCO Engineering for The Environment Agency
Stakeholders
Natural England, Wessex Chalk Stream and Rivers Trust , Piscatorial Society
Tasks
Five Rivers worked with AMCO engineering to complete this complex habitat improvement project on a 1.4km section of the River Avon. Works included:
- Breach formalisation to allow multi species fish passage and agreed flow split. Placement of pre-cast concrete manhole rings with rock infill
- Channel narrowing on leat channel
- Bed lowering on carrier stream
- Modify existing hatches to provide static weirs and permanently open hatch with reduced width. Two hatches were refurbished with steel frames, rising spindle and winding mechanism to retain operability
- Installation of timber sleepers on concrete discharge apron downstream of hatches to form channel.
- Removal of historic eel trap
- Installation of pedestrian footbridge
- Channel narrowing berms at twelve locations totally 600m in length
- Creation of wetland pond and scrape
- Tree hinging at thirteen locations
- Construct large and course woody material sediment traps at ten locations
Key remarks
- Challenging access required specialist plant and construction of temporary roadways
- We added value by working with the designers to produce low cost berms with vegetated turf toe
- River narrowed by up to 40% with low flow channel, ensuring resilience in times of low flow
Effects
- Improve fish passage in all flow conditions
- Delivery of Special Area of Conservation (SAC) and Site of Special Scientific Interest (SSSI) objectives
- Comply with Water Framework Directive targets and implementation of the River Avon Restoration Project
- Reduction in flood risk
- Improving angler access
