A company responsible for one of Michigan’s longest-running groundwater contamination problems has agreed to dig up tainted soil, speed up pumping on the eastern edge of its plume, and pay for outside experts to check its work. The U.S. Environmental Protection Agency announced the administrative settlement with Gelman Sciences LLC on Friday, marking the first major enforcement step since the company’s contamination site was added to the federal Superfund list earlier this year.
The deal requires Gelman to conduct a remedial investigation and feasibility study to pin down the nature and extent of the contamination, according to The Detroit News. It also calls for excavating soil contaminated with 1,4-dioxane from a former burn pit area, increasing groundwater extraction and treatment rates on the eastern side of the plume, and installing additional monitoring wells to nail down the contamination’s easternmost reach. As MLive reported, the agreement also requires Gelman to make grant funding available so an outside group can hire an independent expert to review its work.
A Plume That Started in the 1960s
The contamination traces back to the former Gelman Sciences facility on South Wagner Road, where the company manufactured medical filters from 1963 through 1986. The Detroit News reports the plant discharged wastewater into on-site ponds during that period, and over the decades that followed, the resulting 1,4-dioxane contamination spread through the soil and groundwater beneath Ann Arbor and Scio Township. A University of Michigan student first discovered contamination in the aquifer under Scio Township and western Ann Arbor in the 1980s, and the city closed one of its drinking-water wells in 2001 because of the plume.
Per Michigan Public, the plume now stretches roughly 3 to 4 square miles underground just west of the Huron River and has migrated into aquifers that supply drinking water. EPA added the Gelman Sciences site to the Superfund National Priorities List on March 12, 2026, a move the City of Ann Arbor says shifted regulatory oversight from the state’s Department of Environment, Great Lakes, and Energy to the EPA directly.
Testing Still Turning Up New Detections
The plume remains an active concern for nearby homeowners. The city notes that preliminary results from 2026 residential-well testing, which covered approximately 220 homes in Scio Township, identified 16 new low-level detections of 1,4-dioxane. A year earlier, in July 2025, state officials found the chemical in six Scio Township residential wells at concentrations between 0.33 and 0.86 parts per billion — levels that remained well under EGLE’s 7.2 ppb drinking-water criterion, the same report noted…