No easy target for new contaminant, Duluth wastewater agency finds
As the Western Lake Superior Sanitary District works to better understand PFAS, a survey of its biggest wastewater users found that the chemicals are not in heavy use at those places.
An informal survey of the largest wastewater producers in the region yielded nothing to suggest an easy culprit for the proliferation of contaminants locally known as "forever chemicals."
The survey of 26 permit-holders who discharge large amounts of wastewater through the Western Lake Superior Sanitary District in Duluth failed to yield any major source of per- and polyfluoroalkyl substances, or PFAS.
“We wanted to identify if we have significant amounts of PFAS anywhere, or if there was a larger contributor,” WLSSD spokesperson Karen Anderson said. “That does not appear to be the case at all.”
WLSSD sent surveys in March asking its largest users to take inventory of all chemicals containing the words “perfluoro” or “fluoro” in the name. It received 100% compliance with the surveys.
PFAS have been around for several decades and are an enormous family of human-made chemicals used in grease-resistant food wrappings, clothing, medicine, nonstick coatings, carpeting, firefighting foam and myriad other goods and manufacturing processes.
When built up in the human body, the substances are increasingly known to have a variety of adverse health effects, including high cholesterol, low birth weights and cancer, says the U.S. Environmental Protection Agency’s PFAS profile.
“We didn’t expect to see any large contributors,” Anderson said. “Now, we’re going to have to look more on a micro level once things become more clear.”
Anderson said the agency didn't suspect heavy industrial users, because the local industries don't match up with those commonly known to use PFAS in manufacturing. Paper made locally, for instance, isn't of the grease-resistant variety.
With more than 4,000 variants, some of the chemicals are being found to be more problematic than others. In Wisconsin, the focus has turned to 18 variants, and Anderson said the federal EPA has noted about 40. Despite issuing its first blueprint for how to tackle the PFAS issue earlier this year, the state of Minnesota hasn't yet offered guidance narrowing its focus.
Before it begins to look at smaller manufacturers and businesses locally, Anderson said WLSSD is in a position to wait until the state issues further guidance on a winnowed-down list of which variants are most worrisome. Funding aimed at further understanding PFAS is also at stake in the Minnesota Legislature this session.
“It’s a big issue with a lot to understand,” Anderson said.
In March, the Minnesota Pollution Control Agency identified closed landfills as a major contributor , citing contamination in the groundwater at 97% of the state’s closed landfills, 98 of 101. Some showed PFAS levels at as much as 10 times health guidelines, including issues at all six closed and capped landfills in St. Louis County.
Further examination is being conducted on drinking water wells in those areas.
Not designed to stick to anything, the substances move fast through standing water and can travel long distances. Landfills are rife with products containing PFAS — coatings and chemicals which slough off products into the landfill leachate and then into the groundwater.
Among the 14 billion gallons of effluent it treats annually, WLSSD treats 5 million gallons of trucked-in leachate every year. But it does not have a process for treating PFAS.
While the city of Duluth drinking water has not shown detectable levels of PFAS, some fish in Lake Superior do, including the Lake Superior rainbow smelt, which the Wisconsin Department of Natural Resources advises not to be eaten in more than one meal per month.
PFAS treatment options are under development, and would make for costly additions to current wastewater processes.
WLSSD has said it would rather root out the pollution “upstream” of its treatment plant, which is why it asked its permitted partners to inventory for PFAS. The agency would work to help a manufacturer find an alternative chemical should PFAS be identified as a problem, Anderson said.
Anderson said the PFAS situation is nothing new for WLSSD, which has previously worked to get mercury out of wastewater, and led drives to collect prescription medications before they’re flushed into the wastewater treatment system.
“WLSSD has been an organization that wants to do what’s right,” she said.