1. (a) The requirements of this section shall apply to each groundwater system serving greater than 3,300 people that meets 4-log treatment using chemical disinfection.

2. (b) The O/O of a groundwater system that is subject to this section shall:

   1. (1) Continuously monitor the residual disinfectant concentration using analytical methods specified in 40 CFR 141.74(a)(2) at the approved sampling location;
   2. (2) Record the lowest residual disinfectant concentration each day that water is served to the system’s customers; and
   3. (3) Maintain the department-determined residual disinfectant concentration every day the groundwater system serves water from the groundwater source.

3. (c) If a failure in the continuous monitoring equipment occurs, the O/O of a groundwater system that is subject to this section shall:

   1. (1) Collect grab samples every 4 hours until the continuous monitoring equipment is returned to service; and
   2. (2) Resume continuous residual disinfectant monitoring within 14 days of the failure.

Source. #9600, eff 11-21-09; ss by #12525, eff 6-1-18