NR 809.543(3)(d)(d) The water supplier shall identify all chemical or physical constraints that limit or prohibit the use of a particular corrosion control treatment and document such constraints with at least one of the following:

NR 809.543(3)(d)1.1. Data and documentation showing that a particular corrosion control treatment has adversely affected other water treatment processes when used by another public water system with comparable water quality characteristics.

NR 809.543(3)(d)2.2. Data and documentation demonstrating that the water supplier has previously attempted to evaluate a particular corrosion control treatment and has found that the treatment is ineffective or adversely affects other water quality treatment processes, or both.

NR 809.543(3)(f)(f) On the basis of an analysis of the data generated during each evaluation, the water supplier shall recommend to the department in writing the treatment option that the corrosion control studies indicate constitutes optimal corrosion control treatment for that public water system. The water supplier shall provide a rationale for its recommendation along with all supporting documentation specified in pars. (a) to (e).

NR 809.543(4)(4) Department evaluation of optimal corrosion control treatment.

NR 809.543(4)(a)(a) Based upon consideration of available information including, where applicable, studies performed under sub. (3) and a water supplier’s recommended treatment alternative, the department shall either approve the corrosion control treatment option recommended by the water supplier, or designate alternative corrosion control treatments from among those listed in sub. (3) (a). When approving optimal treatment, the department shall consider the effects that additional corrosion control treatment will have on water quality parameters and on other water quality treatment processes.

NR 809.543(4)(b)(b) The department shall notify the water supplier of its decision on optimal corrosion control treatment in writing and explain the basis for this determination. If the department requests additional information to aid its review, the water supplier shall provide the information.

NR 809.543(5)(5) Installation of optimal corrosion control. Each water supplier shall properly install and operate throughout the public water system’s distribution system the optimal corrosion control treatment approved by the department under sub. (4).

NR 809.543(6)(6) Department review of treatment. The department shall evaluate the results of all lead and copper tap samples and water quality parameter samples submitted by the water supplier and determine whether the water supplier has properly installed and operated the optimal corrosion control treatment approved by the department in sub. (4). Upon reviewing the results of tap water and water quality parameter monitoring by the water supplier, both before and after the water supplier installs optimal corrosion control treatment, the department shall establish ranges for water quality parameters.

NR 809.543(7)(7) Approval of optimal water quality control parameters. The department shall review the water supplier’s recommendations and select the values for the applicable water quality control parameters listed in sub. (3) which reflect optimal corrosion control treatment for the public water system. The department may specify values for additional water quality control parameters to reflect optimal corrosion control for the public water system. The department shall notify the water supplier in writing of these determinations and explain the basis for its decision. At a minimum, the department shall establish all of the following:

NR 809.543(7)(b)(b) A minimum pH value, measured in all tap samples. The value shall be equal to or greater than 7.0, unless the water supplier provides information to indicate that meeting a pH level of 7.0 is not technologically feasible or is not necessary for the public water system to optimize corrosion control.

NR 809.543(7)(c)(c) If a corrosion inhibitor is used, a minimum concentration or a range of concentrations for the inhibitor, measured at each entry point to the distribution system and in all tap samples, that the department determines is necessary to protect the interior walls of the pipes of the distribution system from corrosion.

NR 809.543(7)(d)(d) If alkalinity is adjusted as part of optimal corrosion control treatment, a minimum concentration or a range of concentrations for alkalinity, measured at each entry point to the distribution system and in all tap samples.

NR 809.543(8)(8) Continued operation and monitoring. All water suppliers optimizing corrosion control shall continue to operate and maintain optimal corrosion control treatment, including maintaining water quality parameters at or above minimum values or within ranges designated by the department under sub. (7), in accordance with this subsection for all samples collected under s. NR 809.548 (4). Compliance with the requirements of this subsection shall be determined every 6 months, as specified under s. NR 809.548 (4). A public water system is out of compliance with the requirements of this subsection for a 6-month period if it has excursions for any department-specified parameter on more than 9 days during the period. An excursion occurs whenever the daily value for one or more of the water quality parameters measured at a sampling location is below the minimum value or outside the range designated by the department. The department may delete results of obvious sampling errors from this calculation. Daily values are calculated as follows:

NR 809.543(8)(a)(a) On days when more than one measurement for the water quality parameter is collected at the sampling location, the daily value shall be the average of all results collected during the day regardless of whether they are collected through continuous monitoring, grab sampling or a combination of both. If EPA has approved an alternative formula under 40 CFR 142.16 in the department’s application for a program revision submitted pursuant to 40 CFR 142.12, the department’s formula shall be used to aggregate multiple measurements taken at a sampling point for the water quality parameter in lieu of the formula in this paragraph.

NR 809.543(8)(c)(c) On days when no measurement is collected for the water quality parameter at the sampling location, the daily value shall be the daily value calculated on the most recent day on which the water quality parameter was measured at the sample site.

NR 809.543(9)(9) Modification of department treatment decisions. Upon its own initiative or in response to a request by a water supplier or other interested party, the department may modify its determination of the optimal corrosion control treatment under sub. (4) or optimal water quality control parameters under sub. (6). A request for modification by a water supplier or other interested party shall be in writing, explain why the modification is appropriate, and provide supporting documentation. The department may modify its determination if it concludes that a change is necessary to ensure that the water supplier continues to optimize corrosion control treatment. A revised determination shall be made in writing, set forth the new treatment requirements, explain the basis for the department’s decision, and provide an implementation schedule for completing the treatment modifications.