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EPA Proposes Significant Changes to List of Approved Methods for Analyzing Effluent under the Clean Water Act, Including PCB and PFAS Methods
In the flurry of rulemaking occurring in the waning days of the Biden administration, U.S. EPA signed a proposed rule on December 6, 2024, to update the testing procedures known as methods that are approved for use in analyzing and characterizing pollutants in wastewater and surface waters under the Clean Water Act (CWA). If finalized, this proposed rulemaking would change the test methods that could be used for sampling and analysis of pollutants under the National Pollutant Discharge Elimination System (NPDES) permit program, including for polychlorinated biphenyls (PCBs) and per- and polyfluoroalkyl substances (PFAS). The proposed rule, called the Clean Water Act Methods Update Rule 22 for the Analysis of Contaminants in Effluent (MUR 22), would be the latest update to the list of approved CWA methods in 40 C.F.R. Part 136. Written comments on the proposed MUR 22 rulemaking will be due 30 days after publication in the Federal Register.
EPA’s proposed MUR 22 would add three new EPA analytical methods to Part 136:
- EPA Method 1628 - a method capable of measuring 209 PCB congeners
- EPA Method 1633A - a method capable of measuring 40 PFAS compounds
- EPA Method 1621- a method capable of measuring adsorbable organic fluorine
The MUR 22 proposal would also remove from Part 136 seven PCB Aroclor mixtures (1016, 1221, 1232, 1242, 1248, 1254, and 1260) and their approved test methods. EPA believes that PCBs in the environment may no longer resemble their original Aroclor formulations due to weathering and that the Aroclor methods may be underestimating the actual presence of PCBs. As such, EPA is proposing to replace the Aroclor-based methods with EPA Method 1628, which can detect 209 individual PCB congeners or groups of co-eluting congeners. EPA relies upon its 2021 multi-laboratory study report to support the approval of this proposed new method. On its website, EPA has explained that Method 1628 was developed to meet the following goals: (i) identify and quantify PCBs using individual congeners rather than Aroclors, (ii) be more sensitive than approved Method 608.3, but not so sensitive that it is susceptible to background contamination issues, and (iii) can be implemented at a typical mid-sized full-service environmental laboratory. Issues of background contamination, high sensitivity, and laboratory accuracy have been common criticisms of EPA’s other unapproved method for PCB congener analysis known as Method 1668C. At least one study published in 2024 has raised some questions regarding the accuracy and reliability of EPA Method 1628.
If finalized, these proposed changes to approved PCB methods may impact all dischargers with PCB limits or monitoring requirements in their NPDES permit as EPA anticipates that permitting authorities will require use of the new method upon permit renewal. It may also impact dischargers subject to PCB TMDLs in that new, more sensitive test methods could be required for PCB monitoring.
As indicated above, MUR 22 proposes to add Method 1633 to test for 40 PFAS substances in wastewater and seven other types of media and to add Method 1621 to test for adsorbable organic fluorine. Approval of these methods through finalization of MUR 22 will support the much-anticipated Organic Chemicals, Plastics, and Synthetic Fibers (OCPSF) Effluent Limitations Guidelines and Standards (40 CFR part 414) rulemaking to address PFAS discharges from facilities manufacturing PFAS. Since the first draft version of Method 1633 was publicly- released in 2021, the method has undergone multiple rounds of comments and revisions as well as a multi-laboratory validation study led by the Department of Defense in collaboration with EPA. EPA has stated that comments received from interested parties have resulted in many changes reflected in the proposed final method and that the validation study was used to add formal performance criteria to the method. EPA believes approval of these methods will assist the regulated community by improving the consistency in analysis of parameters.
EPA has also included in MUR 22 several other updates to the list of approved methods in Part 136. Among other things, it is proposing to withdraw several outdated methods; add methods previously published by voluntary consensus standard bodies for PFAS analytes, peracetic acid and hydrogen peroxide; simplify sampling requirements for two volatile organic compounds; and make a series of minor corrections to existing tables of approved methods.
EPA will accept written comments on the proposed rule for 30 days upon publication of the Federal Register notice. If you have questions concerning the proposal or are seeking assistance in preparing comments, please contact Brenda Gotanda or Mike Nines.
