15A NCAC 18C .0707 SOLIDS CONTACT OR UP‑FLOW UNITS
(a) Approval of Solids Contact or Up‑Flow Units. Solids contact or up‑flow clarification units shall be approved only where raw water characteristics are substantially constant and shall not be approved for raw waters that have wide and rapid variations in turbidity or other qualities that would adversely affect the treatment process.
(b) Water Rise Rate. The rise rate shall not exceed 1.0 gallon per minute per square foot of clarification area unless the requirements of Rule .0711 of this Section have been satisfied.
(c) Weir Loading. Weir loading shall not exceed seven gallons per minute per foot of weir length. Horizontal flow to the collection trough shall not exceed 10 feet.
(d) Speed Agitator Equipment. Mixing and flocculation shall be accomplished by means of adjustable, variable speed agitator equipment.
(e) Sludge Withdrawal. Sludge withdrawal equipment shall include an intermittent sludge removal mechanism controlled by an adjustable automatic timer.
(f) Basin Drain. The basin shall be provided with a bottom drain that is of sufficient size to empty the basin in two hours or less.
History Note: Authority G.S. 130A‑315; 130A‑317; P.L. 93‑523;
Eff. January 1, 1977;
Readopted Eff. December 5, 1977;
Amended Eff. July 1, 1994.