Trace levels of PFAS detected in more city wells
Tuesday, April 9, 2019 - 11:45am
Madison Water Utility has received test results after sampling in March for PFAS compounds at 14 of the city’s 23 municipal wells. Remaining wells will be tested in the coming months.
Results show that trace levels of PFAS compounds have been detected at four additional wells located on both the east and west sides of the city. That brings the total number of wells with detections of PFAS to six (see map). PFAS compounds were not detected at the other seven wells tested last month.
The following wells show PFAS detections:
- Well 6 on University Ave. showed detections of a handful of PFAS compounds at levels too low to accurately measure. The EPA has established a Lifetime Health Advisory Level for two types of PFAS (PFOA and PFOS) of 70 parts per trillion (ppt). PFOS was not detected in Well 6. PFOA was found at an estimated level of 0.8 ppt.
- Well 9 on Spaanem Ave. had detections of PFOA and PFOS at an estimated level of 0.8 ppt, as well as trace levels of a mixture of other types of PFAS compounds, most of which are again at levels too low accurately measure.
- Well 14 on University Ave. had trace detections of a mixture of PFAS compounds. Combined PFOA and PFOS concentrations are estimated to be 2.4 ppt.
- Well 11 on Dempsey Rd. had preliminary results that indicate the presence of very low levels of PFAS. However, the lab flagged those results due to its own quality control issues, so the well will be re-sampled in the coming weeks.
- Well 15 on East Washington Ave. was re-tested shortly before it was taken offline in March. Results show PFAS levels at the well are stable, neither increasing nor decreasing significantly. The combined concentration of PFOA and PFOS remain between 11 and 12 ppt.
- Well 16 on Mineral Point Rd. was also re-tested. Results show detections of a mixture of PFAS compounds, most at concentrations too low to accurately measure. In previous testing, no PFOA or PFOS was detected at the well. In this round of tests, the two chemicals were detected at an estimated concentration of 2.5 ppt.
Find more testing details on Madison Water Utility’s PFAS Testing and Information page.
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Investigating PFAS in Madison
This isn’t the first time Madison Water Utility has worked to test all city wells for PFAS (or per- and poly-fluoroalkyls), a widespread class of chemicals used in non-stick cookware, water-resistant clothing, food packaging, stain-resistant upholstery and carpeting, and firefighting foams.
In 2015, the utility tested all wells for PFAS but found nothing. MWU water quality manager Joe Grande says the utility has since made the decision to look harder, testing for more types of the chemicals down to lower detection levels.
“Most utilities pretty much test what they’re told to test by their regulators, whether it’s state or federal,” Grande says. “So most water utilities are not proactively out looking for substances and doing this level of testing. We’re subjecting each of our wells to greater scrutiny – greater examination and analysis.”
City officials believe the PFAS compounds found at Well 15 are likely coming from nearby Truax Air Field, where PFAS were found in shallow groundwater and have been used in firefighting foams. But detections at other wells are more of a mystery.
“The sources of PFAS are currently unknown. We’re talking about really trace level detections, anywhere from less than one part per trillion to around 5 parts per trillion. Those are the typical concentrations that we’re finding,” Grande explains.
He notes that PFAS chemicals are widespread and don’t easily break down, which means that extremely small amounts of the compounds could be found just about anywhere – if you look closely enough.
“I think when you’re looking at the trace, trace levels that these analytical methods are able to detect, if you’re looking hard for these substances, you’re often going to find them.”
Madison Water Utility is working with a handful of labs that can modify the EPA’s standard method of analysis for PFAS compounds. The standard method currently looks at 18 different types of chemicals. The modified method looks at 24 to 30. But the specific types of additional chemicals analyzed and the levels at which they can be detected vary from lab to lab.
“It varies based on the specific contaminant that you’re looking at. There really isn’t any uniformity,” Grande says.
Grande isn’t aware of any other water utilities in Wisconsin that are using these advanced tests to look for PFAS, and if they are, the results are not being publicly reported. That means Madison Water Utility is alone in the state when it comes to understanding the pervasive nature of PFAS.
“This is the first time that we’ve found many of these PFAS compounds, and there’s not a lot of information about them,” he says. “We don’t really have a bar to measure ourselves against both in terms of testing and the results.”
Although Public Health Madison Dane County does not consider water from any Madison well to be a threat public health, including those with PFAS detections, Grande knows people will be concerned.
“That’s something that I always worry about. We put out an Annual Report to our customers on everything we’ve found in our water. It’s a pretty comprehensive list because there are a lot of man-made and naturally-occurring contaminants detected at low levels. That goes for cities and towns across the state and across the country,” he says. “What’s different about PFAS is that this is new. This is the first time that people are hearing or knowing about this, and it can sound scary. We don’t want to frighten people, but we have an obligation to let them know what we’re finding, even if the levels are very, very low.”
Madison Water Utility is hoping to have a complete data set with detailed PFAS testing results for all wells by the end of this fall.
Because of a lab quality control error, the utility will re-test Well 11 and Well 9.
“The lab asked us if we wanted to run the tests again, but it was outside the hold time, which meant the samples were old,” Grande explains. “So we just asked them to cancel the tests, and then we’ll resample.”
Well 9 water was also tested at another lab, so Grande is using that lab’s results for the time-being. Preliminary analysis at Well 11 does indicate low-level detections, but the utility hopes to have more specific data after re-testing.
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