Scio Township Identifies Additional Residential Drinking Water Wells with 1,4- Dioxane


The following was issued by Scio Township on Nov. 6, 2021:

Scio Township, Michigan. – For years many residential wells in Scio Township have been sampled for 1,4 – dioxane (dioxane) as a result of the large plume of groundwater contamination caused by the former Gelman Sciences facility. The Michigan Department of Great Lakes, Environment and Energy (EGLE) contracts with the Washtenaw County Health Department (WCHD) to conduct long-term monitoring of drinking water wells around the plume. Drinking water wells within 1,000 feet of the estimated plume boundary are included in this state-funded monitoring. Approximately 218 drinking water wells are sampled either twice per year, once per year or every other year, depending on proximity to the plume and nearby detections. This sampling program has a detection limit of 1 ug/L (or part per billion).

Due to concerns about potential movement of the dioxane plume to residential areas located north of M-14, Scio Township has conducted its own sampling which expands on the state-funded program and uses a testing method which detects dioxane below 1 ug/L. The Township performed residential drinking water well sampling for dioxane on 19 wells in July and September of 2021. Low levels of dioxane were discovered at 1 location which had previous detections under the state-funded program and at 2 locations which had not been previously sampled. One of these locations is a significant distance north of the estimated northern boundary of the plume as delineated with existing data. All other samples were non-detect for dioxane. The residents have all been informed of the sample results.

The wells were sampled using a United States Environmental Protection Agency (USEPA) dioxane analytical method for residential wells, Method 522, which has a detection limit of 0.12 ug/L. This testing method is more sensitive than the dioxane analytical methods used by Gelman or the state-funded program. At the 2 locations which had not been previously sampled, dioxane was detected at approximately 0.8 ug/L. These2 wells were resampled in September and the levels of dioxane were confirmed. These concentrations are below the State of Michigan drinking water standard for dioxane of 7.2 ug/L. The use of Method 522 testing has long been recommended by advocates for more comprehensive monitoring and cleanup of the dioxane contamination.

The Township plans to sample approximately 15 additional residences in November. These residences were selected based on their proximity to the northernmost detection from the first round of sampling and having similar well depths.

Will Hathaway, Scio Township Supervisor, stated “It was surprising to find the dioxane contamination so far away from the established area of the dioxane pollution. While the level of dioxane in the homeowner wells is deemed safe according to the EGLE drinking water standard, we believe that the residents of Scio Township deserve to know if any dioxane is in their wells using the best science. We will continue to coordinate the Township’s efforts with EGLE and WCHD so that, together, we’re expanding the area of residential wells sampled for dioxane contamination.” Hathaway has worked together with Scio Trustees Kathleen Knol and Jacqueline Courteau to push for more data on the extent of the contamination and faster progress on the Gelman cleanup. All sample results have been provided to EGLE and WCHD.

The Gelman Site is owned by PALL Life Sciences, Inc., a wholly owned subsidiary of Danaher Corporation, and there are no active plant operations. Historically, the plant manufactured filter devices and used dioxane as a solvent. Thousands of pounds of dioxane were discharged to soil, surface water, and groundwater through seepage lagoons, land spray irrigation, and direct discharges at the site. Wastewater disposal practices at the former Gelman plant located near Ann Arbor contaminated on-site and off-site groundwater with the known carcinogen dioxane. The dioxane groundwater plume, which currently is about four miles long and one mile wide, has polluted local lakes, creeks, residential drinking water wells, and a City of Ann Arbor municipal water supply well.

More information regarding dioxane and the state-funded residential sampling program can be obtained at 1,4-Dioxane | Washtenaw County, MI.

CONTACT: Will Hathaway – Scio Township – Supervisor – 734-369-9400 –

Kathleen Knol – Scio Township – Board Trustee – 734-369-9400 –

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