NR 809.543(2)(2) Department decision to require studies of corrosion control treatment by small and medium-size systems. The department may require the water supplier of any small or medium-size system that exceeds the lead or copper action level to perform corrosion control studies under sub. (3) to identify optimal corrosion control treatment for the public water system. NR 809.543(3)(a)(a) Any water supplier performing corrosion control studies shall evaluate the effectiveness of each of the following treatments, and, if appropriate, combinations of the following treatments to identify the optimal corrosion control treatment for that public water system: NR 809.543(3)(a)3.3. The addition of a phosphate or silicate based corrosion inhibitor at a concentration sufficient to maintain an effective residual concentration in all test tap samples. NR 809.543(3)(b)(b) The water supplier shall evaluate each of the corrosion control treatments listed in par. (a) using either pipe rig or loop tests, metal coupon tests, partial-system tests, or analyses based on documented analogous treatments with other public water systems of similar size, water chemistry and distribution system configuration. NR 809.543(3)(c)(c) The water supplier shall measure all of the following water quality parameters in any tests conducted before and after evaluating the corrosion control treatments listed in par. (a): NR 809.543(3)(c)7.7. Orthophosphate (when an inhibitor containing a phosphate compound is used). 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)(e)(e) The water supplier shall evaluate the effect of the chemicals used for corrosion control treatment on other water quality treatment processes. 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)(a)(a) A minimum value or a range of values for pH measured at each entry point to the distribution system.