15A NCAC 18C .1004 DISINFECTION OF FILTERS
(a) After filters have been thoroughly backwashed to remove dust, silt and other foreign matter the entire filter (including filter media, supporting material and underdrain system) shall be disinfected by application of a chlorine solution having a minimum concentration of 50 milligrams per liter (or ppm).
(b) The solution shall be dispersed throughout the filter bed and remain in contact for a minimum of 24 hours.
(c) For treatment equipment that cannot tolerate chlorine, alternate disinfection procedures as recommended by the equipment manufacturer may be used if equivalent to the disinfection procedure using chlorine.
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.