Debris Management Trashracks Screen Cleaning Systems
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.
Trashracks
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.
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
Cleaning Systems
Main Criteria for Cleaning Systems Effective, reliable, proven, approved by NMFS Head differential to initiate cleaning = 0.1 ft Automated cleaning for most systems
Traveling Brush Cleaning System
Air Burst Cleaning System
Water Jet Cleaning System
Rotation – Vertical Traveling Screens Cleaning System
Rotation – Drum Screen Cleaning System
Flow Distribution and Balancing
Approach flow – poor conditions
Approach flow - good conditions
Correcting Channel Configuration – Hydraulic Modeling
Channel Configuration – Approach Flow Conditions
Balancing Screen Approach Velocity
Baffles for Adjusting Approach Velocity
Swift FSC – Offset Orifice Baffle Panels
Balancing Rotary Drum Screens
Cylindrical Screen Without Internal Baffles
Cylindrical Screen With Internal Baffles