SECTION .2200 - GROUND WATER SYSTEMS
15 A NCAC 18C .2201 APPLICABILITY AND RESIDUAL DISINFECTANT CONCENTRATIONS
(a) Applicability. The provisions of this Section apply to all ground water systems. A ground water system is defined as any public water system that uses ground water including a consecutive system receiving finished ground water. A ground water system does not include public water systems that combine all of their ground water with surface water or with ground water under the direct influence of surface water prior to treatment under Subpart H.
(b) Disinfection. Systems providing chemical disinfection in accordance with 15A NCAC 18C .0402(j) shall measure residual disinfectant concentrations. The locations and concentrations shall be as follows:
(1) Water entering the distribution system. The residual disinfectant concentration shall not be less than 0.2 mg/1 measured as free chlorine when chlorine is the singular applied disinfectant and shall not be less than 1.0 mg/l measured as total chlorine when ammonia and chlorine are applied disinfectants for more than two consecutive daily visits for systems that are collecting grab samples and not more than four hours for systems that perform continuous monitoring.
(2) Water in the distribution system at Coliform Sampling Sites. The residual disinfectant concentration shall not be less than 0.2 mg/1 measured as free chlorine when chlorine is the singular applied disinfectant and shall not be less than 1.0 mg/l measured as total chlorine when ammonia and chlorine are applied disinfectants.
(3) Water in the distribution system at Maximum Residence Time Sites. Systems shall measure residual disinfectant concentrations at maximum residence time sites or at other locations with high water age. The residual disinfectant concentrations at these locations shall be at detectable levels as set forth and calculated in 40 C.F.R. 141.72(a)(4) and (b)(3).
History Note: Authority G.S. 130A-315; P.L. 93-523;
Eff. October 1, 2009;
Pursuant to G.S. 150B-21.3A, rule is necessary without substantive public interest Eff. November 23, 2015.