Our experience in river restoration design and construction for the Environment Agency

1. Our experience in river restoration design and construction for the Environment Agency Céline Gallay Senior Engineer Halcrow Group Ltd Gallayc@halcrow.com

2. Introduction I will discuss the following topics: • Understanding the design and information on how to restore  • Landowner engagement, constraints and buy-in into the design • Our experience of framework contractors in river restoration • The need for flexibility in the design and adequate supervision • How to program the works for the low flow period River restoration design and construction - Celine Gallay

3. Understanding the design and information on how to restore • Simple design with two categories: structures and in-river restoration works • Structures: balance design life, Eurocode standards / structures similar to historical structures • Conflict between different protected species in different channels: the client must prioritise species at an early stage • RRC manuals: good source of information on restoration techniques • More information on ideal flow conditions to provide good habitats for different species would be useful River restoration design and construction - Celine Gallay

4. Landowner engagement, constraints and buy-in into the design • Consultation of landowner is required at the earliest opportunity ideally with outline design • Good to have a showcase project. E.g. Barton Court on Kennet • Convincing the landowner that fish will not be lost due to removal of weed rack • Strategic River Avon Restoration : removal of weirs/hydroelectric schemes River restoration design and construction - Celine Gallay

5. Our experience of framework contractors in river restoration • Works have been delivered through the NCF or the Minor Works Framework • Competent framework Contractors to build structures but some lack experience in river restoration techniques • Wylye: river restoration works were carried out by a fencing sub-contractor • Avington: stone riffle rolled to a flat finish • Lessons learnt: during tender process, a client should request CVs of key construction staff for the works, which demonstrate past experience in river restoration River restoration design and construction - Celine Gallay

6. The need for flexibility in the design and adequate supervision • Flexible design to accommodate protected species. E.g. water voles at Avington • Not an exact science – design needs to be adapted on site • Importance of Environmental Clerk of Works on site and a site supervisor (part-time basis) River restoration design and construction - Celine Gallay

7. How to program the works for the low flow period • Best period from mid-July to mid-October during the low flow season • Budget allocated for the whole project in the same financial year (April to March) resulting in a great challenge to have works on site before September. • Programme of works was developed with the Environment Agency SW Blandford office: • Reaches of the River Avon and its tributaries in need of River Restoration were identified and prioritised, with a costed action plan taking into account the likely landowner collaboration, • A PAR was prepared for a 5 year programme of works allowing design during a financial year and construction during the summer of next financial year, • This approach also allows the packaging of projects and hence cost savings. River restoration design and construction - Celine Gallay

8. Example of strategic River Restoration Project (River Avon) 5-year programme River restoration design and construction - Celine Gallay

9. Conclusion • Additional information on ideal flow conditions for protected species would be useful • Early landowner engagement is essential • Selected EA framework contractor for tenders should demonstrate past experience in river restoration • Flexible design and adequate site supervision are required • A more strategic catchment base approach to river restoration should be considered to provide better value for money River restoration design and construction - Celine Gallay