DGALN - Direction de l'Eau et de la Biodiversité London meeting 11st december Mixing zones Guidance Strategies to reduce mixing zones Y. Aujollet – MEEDDAT / IRSN H. Verhaeghe – Water Agency of Artois Picardie Ministère de l'Écologie, de l'Énergie, du Développement durable et de l'Aménagement du territoire

Pages 2 London meeting 11st december 2008 DGALN - Direction de l'Eau et de la Biodiversité SUMMARY Programmes of Measures and Pollution control 4 Discharges characteristics 5 Design and construction of outfalls 6 Definition 3 Conclusion 7

3 3 3 London meeting 11st december 2008 DGALN - Direction de l'Eau et de la Biodiversité Compliance with best available techniques (BAT) is a prerequisite for the designation of mixing zones. Therefore the guidance document should firstly include instructions for the usage of emission controls to comply with BAT (e.g. with reference to BREF notes). Agree with German add to Chapter 3.0. About compliance with BAT. Starting point

4 4 4 London meeting 11st december 2008 DGALN - Direction de l'Eau et de la Biodiversité Programmes of Measures and Pollution control

5 5 5 London meeting 11st december 2008 DGALN - Direction de l'Eau et de la Biodiversité Discharge characteristics Discharge: Discharge flow: Average over 24 hours or 2 hours ? Effluent parameters (value for effluent concentration and flow : mean, maximum values) River: Average of the minimum river flows over 5 years ? River parameters (seasonal variability : flow/depth/width) Mixing zone: Mixing zone acceptability (why 10% ?) Check point – boundary of the mixing zone. EQS-MAC mixing zone (maximum dimension) ? Special areas: Protected areas of annex IV WFD (no mixing zone). Problematic of drink waters taking (outside of a mixing zone) Harbour, coastal waters

6 6 6 London meeting 11st december 2008 DGALN - Direction de l'Eau et de la Biodiversité Design and construction of outfalls Mixing zone design optimisation: BAT application Outlet diameter Diffusers configuration Position of the port Port orientation

7 7 7 London meeting 11st december 2008 DGALN - Direction de l'Eau et de la Biodiversité Conclusion Strategies for mixing zones reduction To define a calendar for the progressive reduction of the maximum dimension of each mixing zone : River width / Years To define a calendar for the reduction of the maximum mixing zone coverage of a waterbody : % / Years Other alternative : Link with reducing some substances emissions in industrial process : % ELV / Years.