- (a) The requirements of this section shall apply to each groundwater system serving 3,300 or fewer people that meets 4-log treatment using chemical disinfection.
(b) The O/O of a groundwater system that is subject to this section shall:
- (1) Monitor the residual disinfectant concentration using analytical methods specified in 40 CFR 141.74(a)(2) at the approved sampling location, either continuously or on a daily basis by taking a daily grab sample during the hour of peak flow or another time designated by the department;
- (2) Record the residual disinfectant concentration each day that water is served to the system’s customers; and
- (3) Maintain the department-determined residual disinfectant concentration every day the groundwater system serves water from the groundwater source.
- (c) The O/O of a groundwater system that is subject to this section shall collect follow-up grab samples every 4 hours if any daily grab sample measurement falls below the established residual concentration level, until the required residual concentration is met.
Source. #9600, eff 11-21-09; ss by #12525, eff 6-1-18