By Shereen Siewert

State-mandated environmental cleanup at a Wausau park is now complete, but new soil tests suggest more widespread contamination and the need for more remediation, according to the city’s environmental consultant.

Wausau in 2019 contracted with REI to investigate contamination and spearhead cleanup activities at Riverside Park, 100 Sherman St., after years of back and forth with residents and environmental groups seeking remediation in the neighborhood. A site investigation report was submitted to the Wisconsin Department of Natural Resources in 2021, which was subsequently approved. Cleanup began last year.

Ultimately, more than 18,00 tons of impacted soil were evacuated from the park and transported to the Marathon County Landfill for disposal, and the excavated areas were backfilled with borrow and topsoil.

Now, REI is recommending additional site investigation in the park, where dioxin has been detected on multiple occasions and at multiple sites.

In a January 2024 report sent to Public Works Director Eric Lindman, REI hydrogeologist Matthew Michalski and environmental engineer Eric Bradfish summarized their findings and said soil samples taken after the initial July 2023 round of excavation showed additional contamination in some areas. Another round of excavation, in October 2023, attempted to remove the contamination, but sidewall samples showed the contamination remained in a larger area.

One sample was taken in an area where stormwater flowed into a culvert that was previously located inside Riverside Park, and was identified as a likely source of dioxin.

REI is asking the DNR to determine whether the city or another entity is responsible for further testing and cleanup.

Environmental engineers say the samples may suggest a larger field of contamination throughout the community near Riverside Park, an issue that has long been a tension point between neighborhood residents and city officials. Read more about the controversy here.

Some city leaders, including Dist. 3 Alder Tom Kilian, are urging the city to respond in a comprehensive manner moving forward.

“I would like to see that their concerns are recognized and we make sure that this hasn’t migrated into their backyards,” said Kilian, who has been at the forefront of fighting for cleanup in the River Street neighborhood for years. Kilian made the remarks Monday at the city’s Parks and Recreation Committee meeting.

Also on Monday Dist. 5 Alder Gary Gisselman applauded the progress made to date, but said the city’s work is not yet done with respect to protecting the public and ensuring the park is safe.

“This cleanup has been a long time coming,” Gisselman said. “I would hope this committee moves forward with the work that needs to be done.”

The DNR will now review the findings and make recommendations.

What is dioxin? The EPA explains

Dioxins refers to a group of toxic chemical compounds that share certain chemical structures and biological characteristics.

  • Dioxins are called persistent organic pollutants (POPs), meaning they take a long time to break down once they are in the environment.
  • Dioxins are highly toxic and can cause cancer, reproductive and developmental problems, damage to the immune system, and can interfere with hormones.
  • Dioxins are found throughout the world in the environment, and they accumulate in food chains, concentrating mainly in the fatty tissue of animals.
  • More than 90% of typical human exposure is estimated by EPA to be through the intake of animal fats, mainly meat, dairy products, fish, and shellfish.

What does dioxin look like?

Pure dioxin looks like white crystalline needles. In the environment, however, it generally is dispersed and attached to soil and dust particles and is invisible to the eye.

Where does dioxin come from?

Industrial activities: Dioxin is not produced or used commercially in the United States. It is a contaminant formed during the production of some chlorinated organic compounds, including a few herbicides such as Silvex. Over the past decade, EPA and industry have been working together to dramatically reduce the production of dioxin and its release to the environment.

Although environmental levels of dioxins have decreased in the last 30 years, dioxins are extremely persistent compounds and break down very slowly. In fact, a large part of current exposures to dioxins in the United States is due to releases that occurred decades ago (e.g., pollution, fires).

Even if all human-generated dioxins were eliminated, low levels of naturally produced dioxins would remain. EPA and its government partners are looking for ways to further reduce dioxins entering the environment and to reduce human exposure to them.

How can dioxin affect my health? The World Health Organization explains

Short-term exposure of humans to high levels of dioxins may result in skin lesions, such as chloracne and patchy darkening of the skin, and altered liver function. Long-term exposure is linked to impairment of the immune system, the developing nervous system, the endocrine system and reproductive functions.

The developing fetus is most sensitive to dioxin exposure. Newborns, with rapidly developing organ systems, may also be more vulnerable to certain effects. Some people or groups of people may be exposed to higher levels of dioxins because of their diet (such as high consumers of fish in certain parts of the world) or their occupation (such as workers in the pulp and paper industry, in incineration plants, and at hazardous waste sites).