Compliance requirements for per- and polyfluoroalkyl substances

Compliance requirements for per- and polyfluoroalkyl substances. (1) MCL compliance determination. (a) Compliance with MCLs for regulated PFAS under s. NR 809.221 (1) must be determined based on the analytical results obtained at each entry point. (b) For a system monitoring quarterly, compliance with the MCL is determined by the running annual average at each entry point. (c) If a system fails to collect the required number of samples specified under s. NR 809.223 , this is a monitoring violation as described under s. NR 809.226 (3) , and compliance calculations must be based on the total number of samples collected. (d) A system monitoring triennially that has a sample result equal to or exceeding the trigger level of 2.0 ng/l for either PFOS or PFOA, 5 ng/l for HFPO-DA, PFHxS, or PFNA, or a Hazard Index of 0.5 for the Hazard Index, must begin quarterly sampling for all regulated PFAS in the next quarter at the entry point. A system monitoring annually that has a sample result equal to or exceeding the MCL of 4.0 ng/l for either PFOS or PFOA, 10 ng/l for HFPO-DA, PFHxS, or PFNA, or a Hazard Index of 1 for the Hazard Index, must begin quarterly sampling for all regulated PFAS in the next quarter at the entry point. (e) Except as provided in this paragraph, if a sample result exceeds an MCL, the system will not be considered in violation of the MCL until it has completed one year of quarterly sampling at the entry point with the triggering sample used as the first quarter of monitoring for the running annual average calculation. However, whenever a sample result in any quarter, or quarterly average if more than one compliance sample is available in a quarter because a confirmation sample was required by the department, causes the running annual average to exceed the MCL at an entry point regardless of the subsequent quarterly monitoring results required to complete a full year of monitoring, the system is out of compliance with the MCL immediately. (f) A system must calculate compliance using the following methods, as applicable, to determine MCL compliance at each entry point: 1. For each PFAS regulated by an individual MCL, calculation procedures are as follows: a. For a system monitoring quarterly, divide the sum of the measured quarterly concentrations for each analyte by the number of quarters samples were collected for that analyte during the consecutive quarters included in the calculation. If more than one compliance sample for that analyte is available in a quarter because a confirmation sample was required by the department, the system must average all the results in a quarter and then average the quarterly averages. Rounding does not occur until the end of the calculation. If the running annual average exceeds the MCL, the system is not in compliance with the MCL requirements. b. For a system monitoring annually, if the concentration measured is equal to or exceeds an MCL for regulated PFAS, the system is required to initiate quarterly monitoring for all regulated PFAS beginning in the next quarter at the entry point, with the triggering sample result used as the first quarter of monitoring for the running annual average calculation. c. For a system monitoring triennially, if the concentration measured is equal to or exceeds the trigger level as defined under s. NR 809.223 (1) (f) , the system is required to initiate quarterly monitoring for all regulated PFAS beginning in the next quarter at the entry point, with the triggering sample result used as the first quarter of monitoring for the running annual average calculation. d. For the purpose of calculating MCL compliance, if a sample result is less than the practical quantitation level for a regulated PFAS in Table Dk, zero is used for that analyte solely for the purpose of calculating the running annual average. 2. For each PFAS regulated under the Hazard Index MCL, calculation procedures are as follows: a. For a system monitoring quarterly, divide the observed sample analytical result for each analyte included in the Hazard Index by the corresponding HBWC under s. NR 809.221 (1) to obtain a hazard quotient for each analyte for each sampling event at each entry point. Sum the resulting hazard quotients together to determine the Hazard Index for the quarter. If the department requires a confirmation sample for an analyte in the quarter, the system must average these results for each analyte in that quarter and then determine the hazard quotient or quotients from those average values, then sum the hazard quotients. Once the Hazard Indices for the individual quarters are calculated, they are averaged to determine a running annual average. If the running annual average Hazard Index exceeds the MCL and two or more Hazard Index analytes had an observed sample analytical result at or above the practical quantitation level in any of the quarterly samples collected to determine the running annual average, the system is in violation of the Hazard Index MCL. No rounding occurs until after the running annual average Hazard Index is calculated. b. If the Hazard Index calculated using the results of an annual sample equals or exceeds the Hazard Index MCL, the system must initiate quarterly sampling for all regulated PFAS beginning in the next quarter at the entry point, with the triggering sample result used as the first quarter of monitoring. c. If the Hazard Index calculated using the results of a triennial sample equals or exceeds the Hazard Index trigger level, the system must initiate quarterly sampling for all regulated PFAS beginning in the next quarter at the entry point, with the triggering sample result used as the first quarter of monitoring. d. If a sample result is less than the practical quantitation level for a regulated PFAS in Table Dk, zero is used for that analyte solely for purposes of calculating the running annual average. (2) Detection of PFAS not listed under s. NR 809.221. Any detection of a PFAS contaminant not listed under s. NR 809.221 (1) must be reported to the department with the other monitoring reports required under this section. The laboratory must indicate whether any detected PFAS contaminant not listed under s. NR 809.221 (1) has been confirmed or tentatively identified, and when a numerical result is reported, whether the result is quantitative or an estimate. (3) Use of analytical results. The department may determine compliance or initiate enforcement action based upon analytical results and other information compiled by the department or other state-sanctioned representatives and agencies.