15A NCAC 18C .2002      DISINFECTION

(a)  The provisions of 40 C.F.R. 141.72 are incorporated by reference, including subsequent amendments and editions. Copies may be obtained as set forth in Rule .0102(b) of this Subchapter. These provisions are adopted with the following exceptions:

(1)           Water entering the distribution system. In 40 C.F.R. 141.72 (a)(2), (a)(3), and (b)(2), "0.2 mg/l" of residual disinfectant concentration shall be replaced with "0.2 mg/l measured as free chlorine when chlorine is the only applied disinfectant and 1.0 mg/l measured as total chlorine when ammonia and chlorine are applied disinfectants."

(2)           Water in the distribution system at coliform sampling sites. In 40 C.F.R. 141.72(a)(4) and (b)(3), "undetectable" shall be replaced with "less than 0.2 mg/1 measured as free chlorine when chlorine is the only applied disinfectant and less than 1.0 mg/l measured as total chlorine when ammonia and chlorine are applied disinfectants."

(b) Water in the distribution system at maximum residence time sites. For samples collected at maximum residence time sites or at other locations with high water age as required by Rule .1302(a)(2) of this Subchapter, residual disinfectant concentrations shall be at detectable levels as set forth and calculated in 40 C.F.R. 141.72(a)(4) and (b)(3).

(c)  All surface water treatment facilities shall include chemical disinfection for a minimum 0.5 log Giardia inactivation.

History Note:        Authority G.S. 130A-315; P.L. 93-523; 40 C.F.R. 141.72;

Eff. January 1, 1991;

Amended Eff. April 1, 2014; October 1, 2009;

Pursuant to G.S. 150B-21.3A, rule is necessary without substantive public interest Eff. November 23, 2015;

Amended Eff. July 1, 2019.