Testing has found dioxane in additional drinking water wells in Scio Township just outside Ann Arbor, township officials said. The chemical is carcinogenic, according to the Environmental Protection Agency, and the new test results show the plume of contamination extends further than previously known.
Township officials announced this week that sampling of 15 residential water wells showed four wells were contaminated. All four of the wells were north of M-14 and outside the estimated boundary of the plume.
Gelman Science’s former manufacturing plant in Scio Township created the dioxane plume, which has polluted local lakes, creeks, residential drinking water wells, and a City of Ann Arbor municipal water supply well.
Dioxane levels in the four wells ranged from 0.26 to 1.0 parts per billion – well below the state’s drinking water standard for the chemical at 7.2 ppb.
Still, Scio Township Supervisor Will Hathaway said, the news was concerning.
"The dioxane is spread much further north than had been known previously. Even though this is a very low concentration, there's no doubt that this is dioxane and that it's in the groundwater in this part of the township," Hathaway said.
More than 200 drinking water wells are sampled regularly by Washtenaw County Health Department with funding from the Michigan Department of Great Lakes, Environment and Energy, according to township officials.
But that program's sampling method is not as sensitive as the Environmental Protection Agency-developed sampling method used by Scio Township for the recent tests that turned up the four contaminated wells. Using the federal sampling method on residential areas north of M-14 was a response to concerns from the community by Scio Township.
“This is an area that the township and local activists have been arguing needs to have monitoring wells – sentinel wells – as part of the ongoing effort to track where the groundwater contamination is,” Hathway said.
“This really demonstrates that those concerns are legitimate, and that Gelman really ought to support putting the monitoring wells in those locations. Up to this point, they have opposed doing so.”
Hathaway and other elected leaders said they also intend to make the more sensitive testing method available to homeowners. Hathaway said that many Scio Township residents depend on private wells for their water, but without a monitoring well to detect dioxane, the only steps the township can take is sampling the private wells with a homeowners permission.
He said the township will begin coordinating with the Washtenaw County Health Department and the Michigan Department of Environment, Great Lakes and Energy for regular testing in the part of the township where the plume is known to have spread, but he wants Gelman, the company responsible for the pollution, to do more.
“I'm hoping we can apply pressure immediately to have additional monitoring wells,” Hathaway said. “In the long run I'm hoping that we can bring Gelman around to providing alternative water as a way of addressing this situation. The cleanup of the groundwater has to happen, but in the near term, people need to have reliable drinking water.”
Gelman Sciences is now owned by a parent company called Pall Corporation, which did not respond to requests for comment on the test results.
Roger Rayle is the leader of Scio Residents for Safe Water and chair of Coalition for Action on Remediation of Dioxane. He also said Gelman should do more.
“The original contamination was found by sampling drinking water wells for businesses and homes around Gelman,” Rayle said. "It's sad to say that we're kind of back to that same mode, because there wasn't enough sampling by Gelman to determine where the dioxane actually was, where it's coming from, where it's going and how fast.”
