1. Debris Management
Trashracks
Screen Cleaning Systems

2. Trash racks - Criteria
“Open channel intakes shall include a trash rack which shall be kept free of debris.”
“In certain cases, a satisfactory profile bar screen can substitute for a trash rack.”
Comment - No trashrack would be rare situation - such as an on-river screen.

3. Trashracks

4. Trashracks

5. Trashracks

6. Trashrack Spacing
Salmon can reject passage through small bar spacing's (3”).
Recommend no smaller than 4”, but only go this small if there is a compelling reason to do so.
Usually 6” – 9” spacing works pretty well.
Need to carefully assess what debris may be present.

7. Trashrack Maintenance
Install at a 1:5 (horizontal:vertical) slope (or flatter) for ease of cleaning.
Provide easy access for cleaning.
Provide range of freedom for manipulating debris.
Need to clean trashrack whenever head drop exceeds a few inches, or whenever debris accumulates

8. Cleaning Systems

11. Main Criteria for Cleaning Systems
Effective, reliable, proven, approved by NMFS
Head differential to initiate cleaning = 0.1 ft
Automated cleaning for most systems

12. Traveling Brush Cleaning System

13. Air Burst Cleaning System

14. Water Jet Cleaning System

15. Rotation – Vertical Traveling Screens Cleaning System

16. Rotation – Drum Screen Cleaning System

17. Flow Distribution and Balancing

18. Approach flow – poor conditions

19. Approach flow - good conditions

20. Correcting Channel Configuration – Hydraulic Modeling

21. Channel Configuration – Approach Flow Conditions

22. Balancing Screen Approach Velocity

23. Balancing Screen Approach Velocity

24. Baffles for Adjusting Approach Velocity

25. Baffles for Adjusting Approach Velocity

26. Swift FSC – Offset Orifice Baffle Panels

27. Balancing Rotary Drum Screens

28. Cylindrical Screen Without Internal Baffles

29. Cylindrical Screen With Internal Baffles