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On March 7, 2024, the Illinois Pollution Control Board (Board) moved the Illinois Environmental Protection Agency’s (Agency) proposed amendments to the groundwater quality standards (35 Ill. Adm. Code 620) to First Notice.

The  proposal, PCB R 22-18, establishes, among other standards, groundwater quality standards for six per- and polyfluororalkyl substances (PFAS). The Board is moving forward with the groundwater quality standards (GWQS) as originally proposed by the Agency for five of the six PFAS. As for the sixth proposed PFAS standard, the Board is proposing a slightly higher standard based on the U. S. Environmental Protection Agency’s (USEPA) recently proposed drinking water standards.

At First Notice, the proposed Class I GWQS for the six PFAS are as follows:

• PFBS (perfluorobutanesulfonic acid): 1200 ppt (0.0012 mg/L)
• PFHxS (perfluorohexanesulfonic acid): 77 ppt (0.000077 mg/L)
• PFNA (perfluorononanoic acid): 12 ppt (0.000012 mg/L)
• PFOA (perfluorooctanoic acid): 4 ppt (0.000004 mg/L
• PFOS (perfluorooctanesulfonic acid): 7.7 ppt (0.0000077 mg/L)
• GenX/HFPO-DA (hexafluoropropylene oxide dimer acid): 12 ppt (0.000012 mg/L)

The Board has invited comments from the rulemaking participants on whether several of the proposed PFAS GWQS should be lowered to be consistent with the USEPA’s proposed PFAS drinking water standards.

The Board’s First Notice Opinion and Order also addressed numerous issues raised by the rulemaking participants during hearings held in 2022. Several rulemaking participants questioned why the Agency was moving forward with establishing GWQS for PFAS ahead of establishing drinking water standards. While the Board acknowledged that “it would be ideal if drinking water MCLs [maximum contaminant levels] were available to be used as the basis for GWQS,” the Board ultimately deferred to the Agency’s expertise and agreed that moving forward with the GWQS ahead of establishing drinking water standards was a prudent approach. First Notice Opinion and Order, PCB R 22-18 at 18 (Mar. 7, 2024). Despite arguments to the contrary, the Board also found that the proposed GWQS are technically feasible and economically reasonable. Id. at 67.

The Board moving to First Notice begins a period of at least 45 days during which the Board will accept public comments on the rulemaking proposal. Additional information on this rulemaking can be found on the Board’s docket.