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PFAS Drinking Water Testing Plan
Madison Water Utility will move from semi-annual testing to monthly testing at Well 15 in 2019 to ensure levels of PFAS at the well are stable. After a period of monitoring, the Utility will evaluate the monthly results, and compare them to previous results, to determine whether to continue monthly testing.
While PFAS are currently unregulated under the EPA's Safe Drinking Water Act, the EPA Health Advisory Level for combined PFOA and PFOS is 70 parts per trillion.
No wells tested in Madison showed results above the EPA Health Advisory Level. The level of those chemicals at Well 15 is 10 parts per trillion.
The utility will test for more types of PFAS chemicals in 2019. Samples will initially be sent to two different national labs. One will look for 24 types of PFAS, the other will look for 30. The testing is not required under state or federal regulations, and only a limited number of labs across the country can reliably carry out the expanded tests at such low concentrations
“The Department of Defense has a list of 24 contaminants that they’re typically testing for, and they have an accreditation process for labs that can satisfactorily quantify those 24 PFAS chemicals,” Madison Water Utility water quality manager Joe Grande explains. “The plan is use two labs at least this one time, see how the results compare. If they’re really highly variable between the two labs, we might want to do two tests again.”
Grande notes the testing focuses on PFAS types that were the most widely manufactured and most commonly used in commercial applications like firefighting foams and nonstick and anti-stain materials.
Expecting to find PFAS precursors
So far, six types of PFAS chemicals have been found at low levels at the well, with a total concentration of just over 40 parts per trillion. Grande expects these new tests will detect trace amounts of chemical precursors for some types of PFAS.
“Firefighting foams contain a mixture of PFAS chemicals, and some of the chemicals are not completely formed – they’re called precursors. Our tests this time around will be looking at some of those. When I talk to folks at one of the labs, they feel like these precursors are going to be present. If you find PFOA, PFOS or PFHxS, you often find precursors with them. So we shouldn’t be surprised if we find some of these.”
Madison Water Utility will also continue to periodically monitor PFAS at Well 16, although not on a monthly basis. One type of PFAS (PFHxS) has been detected at trace levels at the well. There is no health advisory level for PFHxS.