Violation of MCLs or requirements related to PFAS

Violation of MCLs or requirements related to PFAS. (1) PFAS MCL violations, both for the individual PFOA, PFOS, HFPO-DA, PFHxS, and PFNA MCLs, as well as the Hazard Index MCL, as listed under s. NR 809.221 (1) , are based on a running annual average, as outlined under s. NR 809.224 . (2) Compliance with s. NR 809.221 (1) must be determined based on the analytical results obtained at each entry point. If one entry point is in violation of an MCL, the system is in violation of the MCL. (3) Each failure to monitor in accordance with the requirements under s. NR 809.223 is a monitoring violation. (4) Failure to notify the department following an MCL violation and failure to submit monitoring data in accordance with the requirements of ss. NR 809.225 and 809.80 are reporting violations. (5) Results for PFAS with individual MCLs under s. NR 809.221 (1) are compared to their respective MCLs, and results for mixtures of 2 or more of the Hazard Index PFAS (HFPO-DA, PFBS, PFHxS, and PFNA) are compared to the Hazard Index MCL under s. NR 809.221 (1) . For determining compliance with the Hazard Index MCL, if only PFBS is reported at any concentration and no other regulated PFAS are in the mixture, it is not a violation of the Hazard Index MCL. If only one of the other PFAS within the Hazard Index (HFPO-DA, PFHxS, and PFNA) is detected and the level of this PFAS exceeds its MCL under s. NR 809.224 (1) (f) 1. a. , only an individual MCL violation is assessed for the individual PFAS detected, and it is not a violation of the Hazard Index MCL. Exceedances of the Hazard Index caused by 2 or more of the Hazard Index PFAS (HFPO-DA, PFBS, PFHxS, and PFNA) and exceedances of one or more individual MCLs can result in multiple MCL exceedances. However, in this instance, for purposes of public notification under Appendix A to subchapter VII, a PWS must only report the Hazard Index MCL exceedance.