(a) Piping and channels throughout the WWTP shall be designed to carry the maximum design flows as follows:
- (1) Gravity influent sewers shall not be surcharged during normal operating conditions;
- (2) Bottom channel corners shall be filleted, with the elimination of pockets and corners where solids can accumulate;
- (3) Suitable gates, stop logs, or plates shall be placed in channels to seal off unused sections that might accumulate solids;
- (4) Non-corrodible materials shall be used for gates; and
- (5) Channels that might not be used for considerable periods of time shall have valved drains.
(b) Flow distribution devices shall be designed to:
- (1) Control organic, solids, and hydraulic loading to WWTP process units;
- (2) Provide distribution to individual treatment units to ensure equal distribution among all units;
- (3) Provide visible status indication for influent flow to each unit via weirs, sluice gates, slide gates, control valves, or other means;
- (4) Provide positive scum and foam removal in all channels and distribution structures that have a trapped-free surface; and
- (5) Not rely on effluent weirs and flow route symmetry for flow control.
- (c) Underflow shear gates for balancing flows shall not be permitted.
Source. (See Revision Note at chapter heading for Env-Wq 700) #8590, eff 3-25-06; ss by #10693, eff 10-15-14; ss by #14258, eff 7-1-25, EXPIRES: 7-1-35