SECTION .2200 - GROUND WATER SYSTEMS
15 A NCAC 18C .2201 APPLICABILITY AND RESIDUAL DISINFECTANT
(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
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.