ANN ARBOR, MI - The toxic chemical 1,4-dioxane has been detected in shallow groundwater beneath Waterworks Park on Ann Arbor's west side.

It's the latest revelation following new investigations into the plume spreading from the former Gelman Sciences property on Wagner Road, and a sign that in certain areas it might be closer to the surface than some would like.

The Michigan Department of Environmental Quality says the concentrations are below the DEQ's precautionary screening levels for risk of vapor intrusion into buildings and there's no immediate risk to public health known at this time.

Jennifer Lawson, the city of Ann Arbor's water quality manager, shows Kevin Lund, Alex Rosen and Dan Hamel a sanitary sewer manhole on Eighth Street next to Slauson Middle School where there's evidence of groundwater seeps on May 25, 2016. In the background is the playground area of Waterworks Park where dioxane has been discovered in shallow groundwater.

But the discovery of dioxane not far below the surface in a park in a relatively dense neighborhood has some citizens concerned about the potential for human exposure, including toxic vapors infiltrating homes and businesses if the shallow plume comes into contact with building foundations and basements.

The DEQ acknowledges it's possible dioxane-contaminated groundwater moving under Ann Arbor's west side could enter buildings as vapor.

"Migration of contaminants from groundwater into indoor air is a new pathway of exposure in connection with the Gelman Sciences plume that the MDEQ is looking at very closely," the DEQ stated in a news release on Monday, Oct. 17.

The DEQ has proposed a new vapor-intrusion screening level of 29 parts per billion for when dioxane-contaminated groundwater is in contact with a building foundation. The dioxane found in shallow groundwater at Waterworks Park is at about 2-3 ppb, according to a report released on Monday.

"Our initial testing shows concentrations of 1,4-dioxane detected in shallow groundwater in a limited area of the city do not exceed proposed screening levels protective of indoor air," Mitch Adelman, the DEQ's district supervisor, stated in the news release the DEQ issued on Monday.

"The MDEQ's first priority is to protect public health," Adelman added. "We are committed to open communications and transparency of our actions in affected communities. We will work with local stakeholders to ensure residents are informed and supported as this process moves forward."

Waterworks Park is directly across from Slauson Middle School and fronts both Eighth Street and Seventh Street. It includes a children's playground, walking trails and grassy fields where people bring their children and dogs to play.

The DEQ worked with Gelman Sciences, which polluted the Ann Arbor area's groundwater with dioxane decades ago, to conduct the latest investigations of shallow groundwater in neighborhoods west and southwest of West Park.

The tests were conducted in response to residents' concerns about vapor-intrusion risks and potentially contaminated water seeping out of the ground.

Citizen activists tracking the issue say they're interested in hearing more about the test results, and it is a concern to them if dioxane has been found in shallow groundwater near people's homes, even in low concentrations.

Even readings showing 2-4 ppb in groundwater close to home basements could be a shock to residents, said Ann Arbor resident Vince Caruso, a member of the Allen's Creek Watershed Group and the local Coalition for Action on Remediation of Dioxane, who called the tests long overdue.

Dan Bicknell, who is credited with discovering the Gelman dioxane plume in the 1980s, is president of Global Environment Alliance LLC.

Bicknell formally documented his concerns about the potential for dioxane to infiltrate basements in the West Park area in a report presented to the DEQ in May. He used hydrogeological cross-sections and historical monitoring well readings to form his theory about a shallow plume and argue there weren't enough shallow wells to assure residents they were safe from exposure.

Dioxane is classified by the U.S. Environmental Protection Agency as likely to be carcinogenic to humans by all routes of exposure. It also can cause kidney and liver damage, and respiratory problems.

Adelman announced at an Ann Arbor City Council meeting in late July that Gelman Sciences agreed to conduct shallow groundwater tests in more than two dozen locations in Ann Arbor and Scio Township to address residents' concerns.

Gelman Sciences retained engineering firm Fleis & VandenBrink to conduct the investigations, collecting groundwater samples from the first occurrence of groundwater at 26 select locations in western Ann Arbor and eastern Scio Township. The locations, chosen by the DEQ, were in areas where the top of the water table was believed to be within 20 feet of the ground surface.

F&V conducted its fieldwork between Aug. 8 and Aug. 17. Samples were submitted to the Gelman Sciences lab for analysis of dioxane and to Ann Arbor Technical Services Inc. for analysis of volatile organic compounds.

The DEQ's staff observed the fieldwork and collected split samples for independent analysis at the DEQ's lab in Lansing.

F&V contracted with TerraProbe for installation of temporary monitoring wells at locations where groundwater was encountered within 20 feet of the surface, which turned out to be 16 of the 26 locations.

The company issued a 227-page report containing its findings, indicating dioxane was detected in two places -- at 2.7-3.3 ppb at a location identified as RL-12 (on the Eighth Street side of Waterworks Park across from Slauson Middle School), and at 1.9-2 ppb at RL-13 (on the Seventh Street side of the park).

Dioxane was detected at 2.7-3.3 parts per billion in shallow groundwater at a location identified as RL-12 (on the Eighth Street side of Waterworks Park across from Slauson Middle School), and at 1.9-2 ppb at RL-13 (on the Seventh Street side of the park).

In addition to dioxane, tests showed other contaminants in certain shallow groundwater samples.

Chloroform was detected at 5-5.8 ppb at RL-2 (along the east side of Seventh Street, just north of West Park) and trichloroethane at 12-14 ppb at RL-7 (at the southwest corner of Bath Street and Seventh Street, across from West Park).

The F&V report states those levels are above reporting limits for those two contaminants, though the detected concentrations of trichloroethane are below the DEQ's proposed vapor-intrusion screening level of 630 ppb for when contaminated groundwater is in contact with a building foundation.

However, the detected concentrations for chloroform are well above the DEQ's proposed residential vapor-intrusion screening level of 1 ppb.

The Gelman Sciences lab found measurable peaks for numerous compounds detected in groundwater samples, including trichloroethylene and trichloroethane at RL-2, dimethyl-hexane at RL-3 (northwest corner of West Park along Seventh Street), RL-4 (along Maple Ridge, a block west of West Park) and RL-8 (southwest corner of West Park along Seventh Street), trichloroethane at RL-7, and tetrachloroethylene at RL-21 (along Bemidji Drive near Virginia Park).

None of those additional compounds are believed to be related to the Gelman Sciences contamination, according to the F&V report.

The report shows the temporary wells that helped find dioxane beneath Waterworks Park had static water levels about five or six feet below surface. The temporary well on the Eighth Street side had a screened interval of six to 11 feet below surface, while the one on the Seventh Street side was 10 to 15 feet below surface.

Bicknell, who has pushed the DEQ to conduct more shallow groundwater tests, said further study is necessary to properly understand the situation.

He has been critical of the way the DEQ went about the initial investigation, saying it might not have actually collected groundwater from the shallow portion of the glacial till aquifer that is impacted with dioxane, but only perched water.

He doesn't think enough has been done yet to identify the location and concentration of the shallow plume and whether buildings near West Park and the surrounding area might be in contact with dioxane.

"The confirmation that dioxane is in very shallow water about the homes is of great concern," he said. "Clearly, further study is required to identify the extent and magnitude of such dioxane groundwater contamination."



As with the Pate family off Jackson Road that was found this year to have had unsafe levels of dioxane in its well water for years, Bicknell argues the DEQ still is not acting in a proactive manner that is protective of public health.

Conan Smith, who dealt with the dioxane plume issue as a Washtenaw County commissioner over the past 12 years, lives on Eighth Street across from Waterworks Park. His property next to Slauson Middle School was identified earlier this year as one of the areas where shallow groundwater is known to seep out of the ground, creating a potential for exposure to dioxane.

Smith said he and his wife, state Sen. Rebekah Warren, are letting the DEQ use their backyard for further testing.

"We have an unusual site in that we are right on Allen Creek, at the bottom of a valley for runoff, and may have a spring bringing water up from below," he said, calling their backyard "a pretty nice wetland."

"Hopefully the state finds it useful for their research," he said.

As for the confirmation of dioxane in the shallow groundwater nearby, Smith said the new findings lend weight to the county's approach to the Gelman plume: become party to the DEQ's lawsuit, fight for stricter standards, and be prepared for the possibility of more direct financial engagement by the public in cleaning up the contamination to protect the local drinking water supply and homes.

"It's a relief that there apparently is no serious immediate public health threat, but we clearly cannot rule out residents' concerns that 1,4-dioxane can volatilize and potentially contaminate basements and homes," he said.

"We are a long way from levels that would raise any alarms, but more aggressive monitoring and cleanup is essential -- where the funds for that come from in a timely way is pretty questionable."