How state tests could miss toxic dioxane in Washtenaw County groundwater

Advocates call for more stringent testing and drinking water standards, polluter pay legislation.
Map of Dioxane groundwater plume under Ann Arbor area. Source: Michigan Department of Energy, Great Lakes & Environment.

Residents and environmental advocates are raising concerns about state plans to test for 1,4-dioxane contamination that has affected drinking water wells in Scio and Ann Arbor Townships. They say the method the state plans to use isn’t sensitive enough to detect low but still harmful levels of the chemicals.

The contamination, which originated at the former Gelman Sciences site on Wagner Road on the border of Ann Arbor and Scio Township, has been tracked in area groundwater for decades, with a large plume spreading underneath much of Ann Arbor’s west side. 

Michigan’s Department of Environment, Great Lakes, and Energy (EGLE) is expanding its testing in Scio Township this spring to include residential wells where the township previously found dioxane using the EPA’s 522 method, which registers levels as low as 0.12 ppb. 

But EGLE’s testing method only detects dioxane down to concentrations of 0.5 ppb. Experts say this difference is significant. 

The EPA’s health advisory level for 1,4-dioxane is 0.35 parts per billion. But since that advisory is non-enforceable, states can set their own drinking water standards for 1.4-dioxane. Michigan’s drinking water standard of 7.2 ppb for 1,4 dioxane is the highest among states that have adopted regulations for the chemical. Massachusetts has the most stringent drinking water guideline for the chemical at 0.3 ppb.

Like PFAS, 1,4-dioxane has been referred to as a “forever chemical” because it doesn’t break down easily in groundwater. It can cause liver and kidney damage and is a likely carcinogen.  

EPA’s risk assessment indicates that a concentration of 1,4-dioxane at 0.35 ppb in drinking water represents a one in a million cancer risk.  

Advocates say testing should detect the chemical at concentrations that increase cancer risk.

“If the cancer risk is assessed as low as 0.35 ppb, the reporting limit for the lab should be at least 0.35 ppb, not 0.5 ppb,” Denise Trabbic-Pointer, a toxics and remediation specialist with Sierra Club Michigan, told Planet Detroit by email.

EGLE Spokesperson Jill Greenberg defended the state’s testing method, saying it conformed with state law and Part 201 of the Environmental Remediation of the Natural Resources and Environmental Protection Act (NREPA) Act 451 of 1994. 

However, the agency changed its dioxane testing methods at least once, lowering its testing threshold from 1 ppb to 0.5 ppb in 2022.

Scio Township performed independent tests on residential drinking water wells in 2021 and 2022, using the EPA’s more sensitive method, and found 1,4-dioxane in areas further north than previously known. These detections ranged from 0.15 ppb to 1 ppb.

Scio Township resident and chair of the Coalition for Action on Remediation of Dioxane (CARD) Roger Rayle told Planet Detroit that the city shouldn’t have to use drinking water wells to find this out.

“That’s not right,” he said.

Detecting dioxane at low levels could be critical to prevent exposure as the pollution migrates, potentially affecting drinking water wells for people like Rayle. Residents and U.S. Rep. Debbie Dingell (D-Dearborn) are pushing for the EPA to add the Gelman site to the national Superfund list, which could change the testing program and allow the agency to clean up contamination and hold the parties responsible for it accountable. 

This decades-long struggle to clean up contamination has also fueled a desire for a new polluter pay law. The state’s landmark polluter pay law was enacted in 1990 and saved Michiganders an estimated $100 million in cleanup costs, but it was gutted by a 1995 law signed by Gov. John Engler. 

State legislators are now working on introducing this legislation, partially in response to the litigation surrounding the Gelman site and the failure to adequately address pollution after years of effort.

The dioxane seeping through the groundwater in Scio Township and Ann Arbor Township, where a well was found to have dioxane at 9.1 ppb in 2022, could also place Ann Arbor’s drinking water intake on the Huron River in greater danger. 

A map of the tests shows at least one positive detection within 1000 feet of the Huron River, just upstream from the Barton Pond drinking water intake.

Based on the extent of dioxane detected at 7.2 ppb, Michigan’s standard for drinking water, the Gelman dioxane plume covers a four-by-one-mile area, extending east from Wagner Rd. to Ann Arbor’s West Park and north from Liberty St. to Miller Ave. 

If Scio and Ann Arbor township’s positive tests were included, this would extend the plume by more than a mile toward the Huron River and Barton Pond, an impoundment on the river where the city of Ann Arbor sources 85% of its drinking water.

“This migration towards Barton Pond… is concerning and increases the marginal risk,” Stephen Colby Brown, a chemist and conservation committee chair for the Sierra Club’s Huron Valley Group, said by email. In other words, the dioxane in the groundwater could add to the dioxane residents are already exposed to from consumer products and river water, potentially making negative health impacts more likely.    

Another threat comes from Honey Creek where Gelman’s treated groundwater is discharged, flowing into the river upstream from Barton Pond. 

In 2019 and 2020, tests found dioxane in city drinking water at 0.039 ppb and 0.03 ppb. The majority of recent samples have been below detection. 

In the meantime, Ann Arbor City Council has studied sourcing water from the Great Lakes Water Authority because of the river’s PFAS and dioxane contamination. However, that switch could cost hundreds of millions of dollars and require the city to build 28 miles of pipeline.     

Pollution and dilution

During CARD’s April meeting, Dan Hammel, EGLE’s project manager for the Gelman site, said that the state expects results for its upcoming tests to be available by September. Sampling will occur across a swath of land from south of the I-94/M-14 interchange near the Gelman site north to the Huron River. There are over 150 monitoring wells in Scio Township, and seven are in place south of Ann Arbor Township. 

A proposed amendment to a consent judgment between the state and Gelman would require additional monitoring wells in both areas. Gelman performs the sampling and analysis of groundwater taken from these wells as part of a plan approved by EGLE.

Yet, these wells only track and evaluate contamination to ensure dioxane isn’t present above Michigan’s 7.2 ppb drinking water standard, potentially missing dangerous levels of chemicals.

Scio Township found at least 26 locations with dioxane pollution when it contracted with Pace Analytical to test well water between July 2021 and August 2022. Data from Scio Township, reviewed by Planet Detroit, shows more than 40% percent of these would not have been detected using EGLE’s 0.5 ppb detection limit.

Rayle criticized EGLE for not changing its testing method to register lower dioxane levels, as the EPA 522 method would.

“We need due diligence to match the scale of the problem,” he said.

However, the EPA would not confirm what testing method it would use if the site was added to the Superfund list.

As for the Honey Creek and its discharges into the Huron River, EGLE says the current permit allows discharges of 1,4-dioxane up to 22 ppb per day, although the monthly average cannot exceed 7 ppb. Brown criticized this method of managing pollution.

“The most galling aspect with this 1,4-dioxane groundwater plume is that it was allowed, by the State’s DEQ, to migrate for over 40 years in the hope it would go away by dilution, he said.” (EGLE was formerly known as the Department of Environmental Quality.)  

“The mantra of apologists has always been ‘dilution is the solution to pollution’, but contaminations are now so widespread and long-lasting that this is no longer plausible,” he said.

‘The only method we have’

At the April CARD meeting, getting the EPA to take on the Gelman site as a Superfund site was a top priority. Rayle said that a Superfund designation was “the only method we have at this point” to clean up the plume, because Gelman has not been a reliable partner in clean up efforts, especially after it was acquired by Pall Life Sciences, which was then acquired by Danaher Corp.

“The lawyers are making all the decisions,” he said.

However, some have expressed concerns that the proposed updated consent judgment could interfere with the Superfund listing process. This would require compliance with the cleanup criteria of 7.2 ppb for dioxane in groundwater, among other provisions. Greenberg said that EGLE expects the updated consent judgment to be approved by the Washtenaw County Circuit Court.

Kathleen Knoll, a Scio Township Board of Trustees member, says the judgment is not as protective as earlier drafts that intervenors had negotiated. She is concerned about language in “many parts of the draft.” It says the agreement would “adequately resolve” environmental concerns covered by the agreement. 

Neither EGLE nor Rep. Dingell believe the consent judgment would delay the listing process.

“Nothing in this consent decree is going to keep the EPA (from) moving forward or harm the potential of this being listed on the national priority (list),” Rep. Dingell said during the meeting. She added that Deborah Shore, EPA Region 5 director, “has been very hands-on on this” and that the agency was doing their own testing at the Gelman site.

The ongoing struggles with cleaning up the Gelman site and getting water tested have galvanized residents to push for a new polluter pay law. In 2021, former State Rep. Yousef Rabhi (D-Ann Arbor) introduced a bill that would have required polluters to restore groundwater to drinking water standards, among other things.

Rep. Jason Morgan (D-Ann Arbor) confirmed he was working on “comprehensive” polluter pay legislation with State. Sen. Jeff Irwin (D-Ann Arbor), although he couldn’t say if this legislation would address legacy contamination at sites like Gelman. His work on the Gelman site while he was a Washtenaw County Commissioner and hitting what he called “brick walls” with state legislation was a major reason Morgan cited for working on polluter pay now.

“Gelman is a perfect example where it is crystal clear that polluters should have to clean up that site without any ambiguity,” he said. “But our current state laws leave just enough ambiguity to tie this up in court for literally decades, trying to get them to clean up their mess.”


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