Types of Positive Barrier Screens  Rotary Drum  Fixed Vertical Plate  Vertical Traveling – belt and panel  Non-Vertical Fixed Plate  Horizontal Fixed Plate  Eicher Screen  Modular Inclined Screens  End-Of-Pipe (Pump) Intake Screens 1

Acceptance of Existing Screens  If constructed prior to 1989, approval of existing screen considered based on: must function as designed and in good working condition. upon replacement, mesh must be replaced with current criterion. provides safe timely and effective passage. no emergent fry at site access allowed for NMFS inspection.

3 Rotating Drum Screens

4

5

6 Rotating Drum Screen

7 Seals

8

9 Rotating Drum Screens - Advantages  Proven fish protection  Self-cleaning by rotation  Passes debris downstream

10 Rotating Drum Screens - Disadvantages  Susceptible to direct hits from large debris  Large civil works are required.  Seals require much maintenance.  Susceptible to abrasions by sand - mesh requires periodic replacement.  Need control to maintain submergence between 65% and 85% - easy step usually.

11 Vertical Fixed Plate Screens

12 Vertical Fixed Plate Screens

13 Vertical Fixed Plate Screens

14 Vertical Fixed Plate Screens

15 Vertical Fixed Plate Screens

16 Vertical Fixed Plate Screens - Advantages  Easy to seal  Mechanically simple  Can be installed on river’s edge - small screens No bypass required Can use profile wire (very strong)  Mechanical/brush cleaning usually effective  Air burst cleaning system is on back side of screen.  Cleaning is started by timer or head loss.

17 Vertical Fixed Plate Screens - Disadvantages  Must be cleaned mechanically  Large bypass flows required  Brush arms can be damaged by large debris.  Circular air burst cleaners do not clean entire screen.

18 Vertical Traveling Screens

19 Vertical Traveling Screens - panels

20 Traveling Screens - Belt

21 Traveling Screens - Belt

22 Traveling Screens - Advantages  Small screens can be installed on riverbank.  Compact civil works  Self cleaned by rotation  Jet sprays provide additional cleaning.

23 Traveling Screens - Disadvantages  Mechanically complex  Seals can be a problem.  Make sure meets all NMFS criteria (old styles may not)

24 Non-Vertical Fixed Plate Screen - Coanda

25 Non Vertical Fixed Plate Screen – Coanda

26 Non-Vertical Fixed Plate Screen

27 Non-Vertical Flat Plate Screens

28 Non-Vertical Fixed Plate Screens - Advantages  No moving parts  No bypass required if built in-river

29 Non-Vertical Fixed Plate Screens - Disadvantages  Self-cleaning may not be reliable  Risk of injury/mortality on screen during low flow  Must raise and control water surface  Tricky, unreliable flow rate control  Adult upstream passage concerns  Potential issues with hydraulic gradients

30 Eicher Screens and Modular Inclined Screens

Eicher Screens

32 End-Of-Pipe Screens

33 Fixed Cylinder Screens Source: Johnson Screens, Inc..

34 Fixed Cylindrical Screens - Advantages  Good option for deep intakes  Air burst cleaning system can be made to be effective  Some off-the-shelf models with water backwash systems meet NMFS criteria for active screens.

35 Fixed Cylindrical Screens - Disadvantages  Out of sight, out of mind  Need sweep velocity to transport debris from screen site.  Air burst systems on large installations don’t always clean entire screen - especially the bottom.  Long, stringy vegetation is a problem on small pump screens.

36 Pump Screens

37 Pump Screens

38 Pump Screens

Passive Screens (not self-cleaned) Selection Criteria :  Only considered for use when site is not suitable for an active screen.  Uniform approach velocity must be apparent from the conceptual screen design.  Approach velocity not to exceed 0.2 ft/s.  The combined rate of flow at the diversion site must be less than 3 cfs.

Passive Screens (not self-cleaned) Maintenance and debris management:  A maintenance program must be approved by NMFS and implemented by the water user.  The screen must be frequently inspected with debris accumulations removed, as site conditions dictate.  Sufficient stream depth must exist at the screen site to provide for a water column of at least one screen radius around the screen face.  The screen must be designed to allow easy removal for maintenance, and to protect from flooding.

Passive Screens (not self-cleaned) Maintenance and debris management:  The debris load must be low.  Sufficient ambient river velocity must exist to carry debris away from the screen face.

Passive Screens  A maintenance program must be approved by NMFS and implemented by the water user.  The screen must be frequently inspected with debris accumulations removed, as site conditions dictate.  Sufficient stream depth must exist at the screen site to provide for a water column of at least one screen radius around the screen face.  The screen must be designed to allow easy removal for maintenance, and to protect from flooding.

43 Passive Screens

44 Passive Screens

Flow Distribution - Passive Pump Screens

Passive Pump Screens - Installation

Passive Pump Screens – Anchor Blocks