On December 7, 2021, the Illinois Environmental Protection Agency (IEPA) filed proposed amendments to Illinois’ groundwater quality standards with the Illinois Pollution Control Board (Board). The proposal includes Class I and Class II groundwater quality standards for six per- and polyfuoroalkyl substances (PFAS), including perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS), perfluorononanoic acid (PFNA), perfluorohexanesulfonic acid (PFHxS), perfluorobutanesulfonic acid (PFBS), and hexafluoropropylene oxide dimer acid (HFPO-DA).  Illinois follows several states that are choosing to regulate PFAS constituents while federal regulation of the constituents is pending. Ubiquitous, PFAS can be found in a variety of consumer products, industrial processes, and fire-fighting foams, and can come to be located throughout the environment.

We previously provided an update on IEPA’s draft proposal for this rule. The current proposal, filed by IEPA with the Board, varies from that draft proposal in several significant ways. First, it adds a standard for the chemical HFPO-DA, sometimes referred to as “GenX,” which had not previously been included. Additionally, the proposed standards for the remaining PFAS constituents, which are set using a revised health-based risk formula, are more stringent than those in IEPA’s draft proposal. Finally, unlike the draft proposal, the filed proposal does not include a combined standard for PFOA and PFOS. The PFAS standards proposed to the Board are as follows:

PFBS 0.0012 mg/L
PFHxS 0.000077 mg/L
PFNA 0.000012 mg/L
PFOA 0.000002 mg/L
PFOS 0.0000077 mg/L
HFPO-DA 0.000012 mg/L

IEPA’s filing of this proposed rule with the Board initiates the official rulemaking process. As part of that process, interested parties will have the opportunity for public comment and participation prior to the promulgation of a final rule by the Board.