1. (a) A facility must use a coarse screening device, unless stated otherwise in this subchapter.
2. (b) A coarse screening device must include a bypass channel sized to handle the peak flow of the facility.
3. (c) A coarse screening device must include a means of diverting flow to the bypass channel.
4. (d) If the primary channel uses a mechanically cleaned coarse screening device, the bypass channel must have a coarse screening device, either manually or mechanically cleaned.

5. (e) Location Requirements.

   1. (1) Any enclosed structure that houses a coarse screening device and contains other equipment or an office must have an entrance that is separated from the other areas by a gas tight partition.
   2. (2) Each coarse screening device enclosure must have a vent fan capable of providing at least 30 air exchanges per hour if staff entry is allowed.
   3. (3) Each coarse screening device must be readily accessible for maintenance and screenings removal.
   4. (4) Any coarse screening device located 4.0 or more feet below ground level must include equipment capable of lifting the screenings to ground level.

6. (f) Screen Openings.

   1. (1) For a manually cleaned coarse screen, the bar openings must be at least 0.5 inch but not more than 1.75 inches.
   2. (2) For a mechanically cleaned coarse screen, the bar openings must be at least 0.25 inch but not more than 1.75 inches.
   3. (3) A manually cleaned coarse screen must use a bar rack sloped at least 30 degrees but not more than 60 degrees from horizontal.
   4. (4) A manually cleaned coarse screen must be attached to a horizontal platform that has provisions to drain and temporarily store the screenings.

7. (g) Hydraulics.

   1. (1) The velocity through the coarse screen bar racks must be at least 1.0 foot per second but not more than 3.0 feet per second at design flow.
   2. (2) The inlet channel for a screening device must minimize deposition of solids.
   3. (3) The flow line of the inlet channel must not exceed 6.0 inches below the invert elevation of the incoming influent.
8. (h) Corrosion Resistance. A coarse screening device and any related structure must resist the effects of a corrosive environment, including long-term exposure to hydrogen sulfide.

Source Note:The provisions of this §217.121 adopted to be effective August 28, 2008, 33 TexReg 6843.