Michigan PFAS Groundwater Cleanup Criteria Revised to Reflect Newly Added State MCLs


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Michigan PFAS Groundwater Cleanup Criteria Revised to Reflect Newly Added State MCLs

By: George Colvin, CPG, CHMM

Published in August 2020 Focus on the Environment Newsletter

The Michigan Department of Environment, Great Lakes, and Energy (EGLE) recently promulgated state drinking water standards for seven per- and polyfluoroalkyl substances (PFAS).  Drinking water standards, also known as maximum contaminant levels (MCLs) are the maximum amount of a contaminant allowed in drinking water. When the amount of a contaminant in drinking water is higher than the MCL, the water supplier must take action such as treatment or follow-up testing. The new Michigan PFAS MCLs, shown on the below table, took effect on August 3, 2020.

Specific PFAS

CAS #

Drinking Water MCL Parts per Trillion (ppt)

Perfluorooctanoic acid (PFOA)

335-67-1

8

Perfluorooctanesulfonic acid (PFOS)

1763-23-1

16

Perfluorononanoic acid (PFNA)

375-95-1

6

Perfluorohexane sulfonic acid (PFHxS)

355-46-4

51

Perfluorohexanoic acid (PFHxA)

307-24-4

400,000

Perfluorobutane sulfonic acid (PFBS)

375-73-5

420

Hexafluoropropylene oxide dimer acid (HFPO-DA)

13252-13-6

370

The establishment of the new MCLs had an immediate effect on Michigan’s previously established generic groundwater cleanup criteria.  Generic cleanup criteria represent concentrations of a hazardous substance in different environmental media (groundwater, soil, and vapor) that allow appropriate risk management decisions regarding contaminated sites. As established under Part 201, Environmental Remediation, of the Natural Resources and Environmental Protection Act, 1994 PA 451, as amended [MCL 324.20120a(5)], state MCLs, once established, are also used as the basis of the generic cleanup criteria for groundwater used as drinking water.  Consequently, the new state drinking water standards of 0.008 µg/L (parts per billion) and 0.016 µg/L, respectively for PFOA and PFOS replaced the previously established residential and nonresidential drinking water cleanup criteria of 0.07 µg/L for the combined concentrations of PFOA and PFOS. The updated generic groundwater cleanup criteria for residential and non-residential groundwater were updated the same day the new MCLs went into effect.

There are currently no generic cleanup criteria for the other five PFAS compounds with recently established MCLs.  In other words, if you search the Michigan EGLE generic groundwater cleanup criteria table for any of the other five PFAS compounds (i.e., PFNA, PFHxS, PFHxA, PFBS, HFPO-DA), you won’t find them despite the fact that they now have MCLs. EGLE must go through the process set forth by statute and rule to establish generic cleanup criteria for the remaining five PFAS compounds. This is somewhat of a formality, however, as for all practical purposes, the MCLs will be considered generic cleanup standards until developed.


George H. Colvin is a hydrogeologist with over 30 years of consulting experience. Much of his experience has focused on RCRA Corrective Action, RCRA closure, and groundwater investigation, monitoring, and cleanup. He holds a BS in Geology from Ohio University and MS in geology and hydrology from Vanderbilt University. He is a Certified Professional Geologist with the American Institute of Professional Geologists, a registered geologist in Kentucky, Pennsylvania, and Tennessee, and a Certified Hazardous Materials Manager.