ANN ARBOR, MI - Weeks after a residential well north of the Ann Arbor city limits showed dioxane contamination above the state drinking water standard, two additional samples drawn on Dec. 6 and tested independently didn’t detect the toxic chemical, though cleanup advocates are calling for months of additional monitoring.
The well became the first in the area more than a mile north of the estimated boundaries of the Gelman plume — pollution that has spread in area groundwater for decades — to exceed the state dioxane standard of 7.2 parts per billion when an Ann Arbor Township test recorded a concentration of 9.1 ppb in October.
Read more: Resident advised to use bottled water after dioxane discovery north of Ann Arbor plume
Township officials announced the result on Dec. 5, saying it underscores insufficient monitoring of the plume and its movement northward toward Barton Pond, the main source of Ann Arbor’s drinking water.
A first township follow-up test in November at the well on Blueberry Lane, north of Skyline High School, showed a 1.9 ppb dioxane level, while subsequent testing through the Michigan Department of Environment, Great Lakes and Energy (EGLE) using a less sensitive method didn’t detect contamination.
That non-detect finding held true with two independently-tested samples taken at the same time on Dec. 6 by both the township and county officials for testing at a state lab, according to Jill Greenberg, an EGLE spokesperson.
State officials verbally informed the homeowner, who had previously been advised to use bottled water as a precaution, of the results and are “actively discussing next steps,” said Greenberg in a statement.
Township officials aren’t resting easy following the latest results, however.
“Our position in Ann Arbor Charter Township is, look this man and his family have dioxane contamination in their well. It’s ranging from a not detect level of 0.12 (ppb) up to 9.1 (ppb) and we have to continue to be proactive and make sure that they’re being able to have bottled water, and we’re looking to the state to continue to understand this dynamic situation,” said Dan Bicknell, an environmental remediation professional credited with discovering the Gelman plume in 1984 and now working with the township on its testing effort.
The township has suggested to continue sampling the well over the next three months for dioxane, classified as a likely carcinogen, he said.
A “cursory review” of historical test results from residential wells shows that fluctuations in dioxane levels over short periods of time aren’t unheard of, Bicknell wrote in an email to EGLE and the Washtenaw County Health Department, including examples of the phenomenon.
An existing court-ordered cleanup plan for the groundwater pollution is “totally deficient in its ability to determine the extent and magnitude of the contamination,” Bicknell said in an interview, adding that relying on residential wells rather than designated monitoring wells to track the contamination is inadequate.
Ann Arbor Township still plans to test sample an additional 15 or 20 wells in the area, focusing on a deeper part of the aquifer, he said.
The effort comes after officials in neighboring Scio Township, where the now defunct Gelman Sciences filter manufacturing site and the nexus of the pollution is located, worked to sample wells north of M-14, concerned about the possible spread of the plume.
Read more: Testing reveals contamination from Ann Arbor dioxane plume in wells near Huron River
“We continually heard from Gelman representatives that it was not advancing toward Barton Pond, but everything we saw indicated it might well be, and then Scio started testing and showing that it was clearly moving both north and eastward,” said Michael Moran, an Ann Arbor Township trustee involved in the efforts to track dioxane pollution.
“Previously we had not had any sample in Ann Arbor Township that had significant levels and certainly not above the drinking level,” he said. That changed this year with the results at the residence on Blueberry Lane, a finding that has residents worried, Moran added.
“They’re concerned. You talk about a carcinogen maybe being in their water, people want to know about it,” he said.
More from The Ann Arbor News:
New test results show dioxane pollution levels in Ann Arbor waters
Michigan Court of Appeals vacates cleanup order in Ann Arbor pollution case
Ann Arbor spending $333K for more wells to track polluter’s pollution
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