Section NR 809.542 - Applicability of corrosion control treatment steps for small, medium and large-size water systems(1) CORROSION CONTROL TREATMENT REQUIREMENTS. Water suppliers shall complete the applicable corrosion control treatment requirements described in s. NR 809.543 by the deadlines established. (a) The water supplier for a large system shall complete the corrosion control treatment steps specified in sub. (4), unless the public water system is deemed to have optimized corrosion control under sub. (2) (b) or (c).(b) The water supplier for a small system and a medium-size system shall complete the corrosion control treatment steps specified in sub. (5), unless the public water system is deemed to have optimized corrosion control under sub. (2) (a), (b) or (c).(2) DETERMINATION OF OPTIMUM CORROSION CONTROL. A public water system is deemed to have optimized corrosion control and is not required to complete the applicable corrosion control treatment steps identified in this section if the public water system satisfies one of the criteria specified in pars. (a) to (c). Any public water system deemed to have optimized corrosion control under this subsection, and which has treatment in place, shall continue to operate and maintain optimal corrosion control treatment and meet any requirements that the department determines appropriate to ensure optimal corrosion control treatment is maintained. (a) A small or medium-size water system is deemed to have optimized corrosion control if the public water system meets the lead and copper action levels during each of 2 consecutive 6-month monitoring periods conducted in accordance with s. NR 809.547.(b) Any public water system may be deemed by the department to have optimized corrosion control treatment if the water supplier demonstrates to the satisfaction of the department that they have conducted activities equivalent to the corrosion control steps applicable to the public water systems under this section. If the department makes this determination, it shall provide the water supplier with written notice explaining the basis for its decision and shall specify the water quality control parameters representing optimal corrosion control in accordance with s. NR 809.543 (6). Public water systems deemed to have optimized corrosion control under this paragraph shall operate in compliance with the department-designated optimal water quality control parameters in accordance with s. NR 809.543 (8) and continue to conduct lead and copper tap and water quality parameter sampling in accordance with ss. NR 809.547 (4) (c) and 809.548 (4), respectively. A water supplier shall provide the department with all of the following information in order to support a determination under this subsection:1. The results of all test samples collected for each of the water quality parameters in s. NR 809.543 (3) (c).2. A report explaining the test methods used by the water supplier to evaluate the corrosion control treatments listed in s. NR 809.543 (3) (a), the results of all tests conducted, and the basis for the water supplier's selection of optimal corrosion control treatment.3. A report explaining how corrosion control has been installed and how it is being maintained to insure minimal lead and copper concentrations at consumers' taps.4. The results of tap water samples collected in accordance with s. NR 809.547 at least once every 6 months for one year after corrosion control has been installed.(c) Any public water system is deemed to have optimized corrosion control if the water supplier submits results of tap water monitoring conducted in accordance with s. NR 809.547 and source water monitoring conducted in accordance with s. NR 809.549 that demonstrates for 2 consecutive 6-month monitoring periods that the difference between the 90 th percentile tap water lead level computed under s. NR 809.54 (3) (c), and the highest source water lead concentration, is less than the practical quantitation level for lead specified in 40 CFR 141.89(a)(1)(ii). 1. The department may deem that public water systems whose highest source water lead level is below method detection limit have optimized corrosion control under this subsection if the 90 th percentile tap water lead level is less than or equal to the practical quantitation level for 2 consecutive 6-month monitoring periods.2. Any public water system deemed to have optimized corrosion control in accordance with this subsection shall continue monitoring for lead and copper at the tap no less frequently than once every 3 calendar years using the reduced number of sites specified in s. NR 809.547 (3) and collecting the samples at times and locations specified in s. NR 809.547 (4) (d) 4. Any water supplier for a public water system that has not conducted a round of monitoring pursuant to s. NR 809.547 (4) (d) since September 30, 1997, shall complete a round of monitoring pursuant to this subsection as specified by the department.3. Any water suppliers for a public water system deemed to have optimized corrosion control pursuant to this paragraph shall notify the department in writing pursuant to s. NR 809.55 (1) (c) 3. of any upcoming long-term change in treatment or addition of a new source as described in that section. The department shall review and approve the addition of a new source or long-term change in water treatment before it is implemented by the water supplier. The department may require any water supplier to conduct additional monitoring or to take other action the department deems appropriate to ensure that the water supplier maintains minimal levels of corrosion in the distribution system.4. As of December 1, 2002, a public water system is not deemed to have optimized corrosion control under this subsection, and the water supplier shall implement corrosion control treatment pursuant to subd. 5. unless the public water system meets the copper action level.5. Any public water system triggered into corrosion control because it is no longer deemed to have optimized corrosion control under this subsection shall implement corrosion control treatment in accordance with the deadlines in sub. (5). Any large system shall adhere to the schedule specified in that paragraph for medium-size systems, with the time periods for completing each step being triggered by the date the public water system is no longer deemed to have optimized corrosion control under this subsection.(3) CRITERIA FOR COMPLETING CORROSION CONTROL TREATMENT STUDIES FOR SMALL AND MEDIUM-SIZE SYSTEMS. Any water supplier for a small or medium-size water system that is required to complete the corrosion control steps due to the exceedance of the lead or copper action level may cease completing the treatment steps whenever the public water system meets both action levels during each of 2 consecutive monitoring periods conducted pursuant to s. NR 809.547 and the results are submitted to the department. If any such public water system thereafter exceeds the lead or copper action level during any monitoring period, the water supplier shall recommence completion of the applicable treatment steps, beginning with the first treatment step which was not previously completed in its entirety. The department may require a water supplier to repeat treatment steps previously completed by the water supplier if the department determines that this is necessary to properly implement the treatment requirements. The department shall notify the water supplier in writing of such a determination and explain the basis for its decision. The water supplier for a small or medium-size water system shall implement corrosion control treatment steps in accordance with sub. (5), including a public water system deemed to have optimized corrosion control under sub. (2) (a), whenever it exceeds the lead or copper action level.(4) TREATMENT STEPS AND DEADLINES FOR LARGE SYSTEMS. Except as provided in sub. (2) (b) and (c), water suppliers for large systems shall complete the following corrosion control treatment steps by the indicated dates:(a) Step 1: The water supplier shall conduct initial monitoring during 2 consecutive 6-month monitoring periods by January 1, 1993.(b) Step 2: The water supplier shall complete corrosion control studies and submit option for optimal corrosion control treatment to the department by July 1, 1994.(c) Step 3: The department shall approve optimal corrosion control treatment by January 1, 1995.(d) Step 4: The water supplier shall install optimal corrosion control treatment by January 1, 1997.(e) Step 5: The water supplier shall complete follow-up sampling by January 1, 1998.(f) Step 6: The department shall review installation of treatment and approve optimal water quality control parameters by July 1, 1998.(g) Step 7: The water supplier shall operate in compliance with the department-approved optimal water quality control parameters and continue to conduct tap sampling.(5) TREATMENT STEPS AND DEADLINES FOR SMALL AND MEDIUM-SIZE SYSTEMS. Except as provided in sub. (2), water suppliers for small and medium-size systems shall complete the following corrosion control treatment steps by the indicated time periods: (a) Step 1: The water supplier shall conduct initial tap sampling until the public water system either exceeds the lead or copper action level or becomes eligible for reduced monitoring under s. NR 809.547 (4) (d). A water supplier exceeding the lead or copper action level shall recommend optimal corrosion control treatment, under s. NR 809.543 (1), within six months after the end of the monitoring period during which the public water system exceeds one of the action levels.(b) Step 2: Within 12 months after the end of the monitoring period during which a public water system exceeds the lead or copper action level, the department may require the water supplier to perform corrosion control studies, under s. NR 809.543 (2). If the department does not require the water supplier to perform such studies, the department shall specify optimal corrosion control treatment, under s. NR 809.543 (4) within the following timeframes:1. For medium-size systems, within 18 months after the end of the monitoring period during which such public water system exceeds the lead or copper action level.2. For small systems, within 24 months after the end of the monitoring period during which such public water system exceeds the lead or copper action level.(c) Step 3: If the department requires a water supplier to perform corrosion control studies under step 2, the water supplier shall complete the studies within 18 months after the department requires the studies be conducted.(d) Step 4: If the water supplier has performed corrosion control studies under step 2, the department shall review and determine adequacy of public water system's optimal corrosion control treatment within 6 months after completion of step 3.(e) Step 5: The water supplier shall install optimal corrosion control treatment within 24 months after the department approves the treatment.(f) Step 6: The water supplier shall complete follow-up sampling within 36 months after the department approves optimal corrosion control treatment.(g) Step 7: The department shall review the installation of treatment and approve optimal water quality control parameters within 6 months after completion of step 6.(h) Step 8: The water supplier shall operate in compliance with the department-approved optimal water quality control parameters and continue to conduct tap sampling.Wis. Admin. Code Department of Natural Resources NR 809.542
CR 09-073: cr. Register November 2010 No. 659, eff. 12-1-10; correction in (2) (c) made under s. 13.92(4) (b) 7, Stats., Register November 2010 No. 659.Amended by, CR 15-049: am. (2) (c) 3. Register March 2016 No. 723, eff.4/1/2016Amended by, correction in (5) (b) made under s. 13.92 (4) (b) 7., Stats.,Register July 2022 No. 799, eff. 8/1/2022.