Effective Debris Management: Trashrack and Screen Cleaning Systems for Open Channel Intakes
This guide discusses essential aspects of debris management for open channel intakes, emphasizing the importance of trash racks that remain free of debris. It outlines criteria for using trash racks and alternative options like profile bar screens. The document covers spacing recommendations to facilitate fish passage, maintenance practices to ensure efficiency, and various cleaning systems such as automated methods, water jets, and brush systems. Proper approach flow and channel configuration are also discussed to optimize performance while balancing hydraulic conditions for effective debris removal.
Effective Debris Management: Trashrack and Screen Cleaning Systems for Open Channel Intakes
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Presentation Transcript
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.
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
Main Criteria for Cleaning Systems Effective, reliable, proven, approved by NMFS Head differential to initiate cleaning = 0.1 ft Automated cleaning for most systems
