Option 7: Cylindrical Bristle Clusters on West or East Weir
Solution
This option would consist of fixing Cylindrical Bristle Clusters (CBCs) on a constructed concrete ramp within either the west or east weir. CBCs have recently been tested by Montali-Ashworth et al (2020), in which an array of CBCs were mounted on the downstream face of a Crump weir, to improve upstream passage of multiple species of fish while maintaining gauging accuracy. Fish essentially utilised the low velocity zones created by the CBBs to facilitate passage. addition, to ensure the successful migration of fish through either of the culverts, fish friendly modifications to the culverts, such as baffles, could be implemented.
Concept Design
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Appraisal
Option 7 has the potential to allow for the safe passage of fish and eels through Shepley Mill, contribute to GEP under the WFD and comply with the Eels Regulations, although Cylindrical Bristle Clusters (CBCs) have been predominately tested for coarse fish, although could be applicable to salmonoids and eels and most likely only work during high flows, unless notches are placed in either west or east weir. Overall the suitability of this option to meet the project objectives is considered Moderate. Would need additional habitat restoration solutions, such as channel narrowing, desilting and bed regrading, planting of silt deposition bars, flow deflectors and refuge areas.