State officials are accepting more feedback on proposed new statewide standards for more than 300 environmental contaminants, including dioxane.
The last public comment period ended in mid-September.
This week the Michigan Department of Environmental Quality released revised proposed rules with a new comment deadline of October 18, and an additional public hearing scheduled for October 17 in Lansing.
According to Sue Leeming, Acting Chief of MDEQ's Remediation and Redevelopment Division, the changes to the proposed clean-up rules based on the first set of comments were significant enough for there to be a second public comment period.
"Because this is so very complicated, we're open to comments," said Leeming. "And we want other people to take a look at these and help us make sure we've got these right."
Leeming said the latest proposed rules still reduce the exposure limit for dioxane in residential drinking water from 85 parts per billion (ppb) to 7.2 ppb.
A dioxane plume has been moving for decades through the Ann Arbor area's ground water.
Leeming said the proposed rules are a comprehensive update to Michigan's clean up criteria for contaminants in soil, groundwater, and air, with the goal of protecting public health and the environment. She said the last update was in 2002.