1. (a) A fine screen may be used in lieu of a coarse screening device.
2. (b) A fine screen is any screen with a clear opening less than 0.25 inch.
3. (c) The use of a fine screen in lieu of a primary sedimentation unit is acceptable only if the design of any downstream treatment unit is based on the amount of five-day biochemical oxygen demand (BOD₅) reduction expected by the fine screen. The BOD₅ reduction percentage must be developed through a study conducted on actual full-scale operation of the proposed fine screen unit.
4. (d) The report must include the justification for any reduction in the size of any treatment unit based on removal of BOD₅ by the use of a fine screen.
5. (e) An owner who claims a BOD₅ reduction credit must include a sufficient number of fine screen units so that any BOD₅ reduction claimed may occur with the largest fine screen unit out of service.
6. (f) A design may include a single fine screen unit if the design includes a bypass channel with a coarse screening device to accept flow when the fine screen is out of service. No BOD₅ removal credit is allowed with a single fine screen design.
7. (g) A course screening device must be provided ahead of a fine screen when the manufacturer of a fine screen recommends prescreening before the fine screen.
8. (h) A collection system equipment prior to the fine screen must be operated to minimize fats, oils, and grease in the wastewater before the wastewater reaches the headworks if fine or micro screens are used.
9. (i) A moving or rotating fine screen must use a continuous cleaning device, such as water jets or wiper blades.
10. (j) A fine screen unit must automatically convey the screenings to a storage area or processing unit that complies with §217.123 of this title (relating to Screenings and Debris Handling).
11. (k) A fine screen must meet its manufacturer's recommendation with respect to velocity and head loss through the fine screen.
12. (l) A fine screen may use a bar rack or perforated plate.

Source Note:The provisions of this §217.122 adopted to be effective August 28, 2008, 33 TexReg 6843.