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.