How risk-based decisions affect residents living near Ann Arbor's dioxane plume
Issues & Ale visited Bill’s Beer Garden in Ann Arbor last night to discuss the Gelman Sciences 1,4dioxane plume of toxic pollution making its way through the city’s groundwater.
Host Lester Graham led a panel of experts through the discussion. Together they answered residents’ questions and discussed ways to reduce risks associated with the contamination.
MLive reporter Ryan Stanton, who covers this issue, was one of the panelists. Stanton said the Department of Environmental Quality has been working to revise Michigan’s standard for dioxane in recent years.
He said in 2010, the EPA determined that dioxane at 3.5 parts per billion (ppb) in drinking water leads to a one in 100,000 risk of cancer. That made the 85 ppb state standard, which was also supposed to lead to a one in 100,000 risk, seem questionable.
“We’re learning that [state standard] was a little off, a little outdated, not protective of public health,” Stanton said. “So the city and county and a lot of citizen activists … have been fighting for three or four years now to really get the DEQ to follow through on revising that state standard.”
Stanton said a new 7.2 ppb standard for dioxane in drinking water was proposed in April.
Mitch Adelman also sat on last night’s panel. He represented the Department of Environmental Quality and surprised the audience with a haiku:
How clean should clean be? Risk-based decision making Clean may be dirty
Adelman said the haiku's point is that risk-based decision making is a hard game to play. It leads to “relative” standards for pollutants.
One question-asker in the audience said her parenting journey too is “all about risk-based decision making.”
“When I hear ‘human carcinogen,’ for me the statistics are zero or 100%,” she said.
Her son is a cancer survivor and as a mother, she said she’s concerned about environmental exposures.
“We are living in a community where we are interfacing with wells and we have no idea what exposure we are allowing to occur to ourselves, our loved ones and our community,” she said.
Adelman responded. He said the city of Ann Arbor gets 80% of its water from the Huron River and 20% from wells.
“One of the wells did show very low levels of the 1, 4 dioxane,” Adelman said. “The city voluntarily stopped using it. So I trust the city is doing a good job of making sure their citizens are drinking safe water.”
Wells polluted by dioxane now are on the west of Ann Arbor, on the edge of Ann Arbor and Scio Township.
Adelman said the DEQ is working to make sure all residents who get water from those wells are fully informed of associated risks.
"It's really tragic that it took the Flint water crisis to focus attention back on how important water is."
But the dioxane plume is not a new issue in Ann Arbor. Stanton said the city has been dealing with the plume for over 30 years now.
Panelists said it's lately, in the aftermath of the Flint water crisis, that attention to the plume has grown.
Roger Rayle was the event’s third panelist. He runs the group Scio Residents for Safe Water.
“It’s really tragic that it took the Flint water crisis to focus attention back on how important water is,” Rayle said.
He said the “pump and treat” technique would be the best way to clean up the plume. That’s when someone drills a well, pumps out the contaminated water, and treats it. He pointed to “UV oxidation” as the best treatment method. It would ensure all carcinogens were removed from the water.
This is not the treatment currently being used to treat the plume, however. Ozone oxidation is the treatment used now. Rayle said that treatment creates a new carcinogen in the water.
Adelman said the DEQ did allow the switch between treatments, which led to the creation of this new carcinogen.
“The discharge limits are permissible under the federal Clean Water Act,” he said.
Hear Ryan Stanton add to the conversation about the current plume cleanup procedure below. He talks about how “a lot more pumping and treating – in terms of quantity – can be done.”
For information on where the plume is now and how it’s spreading, check out this map from the Scio Residents for Safe Water.
You can watch a full video of the event below.