Scio Township identifies additional Drinking Water Wells with 1,4- Dioxane


The following was released by Scio Township on Oct. 3, 2022:

Scio Township, Michigan. – For years many residential wells in Scio Township have been sampled for 1,4–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. Historically this sampling program has had a detection limit of 1 ug/L (or part per billion). However, beginning in June of 2022, samples will be analyzed by the EGLE lab using a detection limit of 0.50 ug/L.

Due to concerns about potential movement of the 1,4-dioxane plume to residential areas located north of M-14, Scio Township has completed four rounds of sampling which expands on the state-funded program and uses a testing method which detects 1,4-dioxane down to 0.12 ug/L. The first round of sampling in July and September of 2021 identified low levels of 1,4- dioxane at one location which had previous detections under the state-funded program and at two locations which had not been previously sampled, and were below 1 ug/L. One of these locations was a significant distance north of the estimated northern boundary of the plume as delineated with existing data.

The second round of sampling was conducted in November of 2021 and included 15 additional residences. This round of sampling identified four additional residences with low levels of 1,4- dioxane, all of which are located north of the estimated plume boundary. The levels of dioxane detected in the four residences ranged from 0.26 ug/L to 1.0 ug/L.

The third round of sampling was conducted the week of May 16, 2022 and included 27 additional residences and a re-sampling of a residence from the second round. Eight additional residences were identified with low-levels of 1,4-dioxane and re-sampling confirmed the presence of 1,4-dioxane in the residence from the second round. The eight residences are all located north of northernmost detection from the second round of sampling. The levels of 1,4- dioxane detected in the nine residences ranged from 0.15 ug/L to 0.89 ug/L.

The fourth round of sampling was conducted the week of August 22 and included 63 additional residences. This round of sampling identified ten additional residences with low levels of 1.4- dioxane, all of which are located in the area where previous sampling occurred between M-14 and the Huron River. The levels of 1,4-dioxane detected in the ten residences ranged from 0.17 ug/L to 1.3 ug/L. The concentrations are below the State of Michigan drinking water standard for 1,4-dioxane of 7.2 ug/L. All other residences tested non-detect for 1,4-dioxane. The residents have been informed of the sample results.

A total of 122 private wells were sampled in all four rounds. Of that total, 26 wells showed the presence of 1,4-dioxane. All of the wells were sampled using a United States Environmental Protection Agency (USEPA) 1,4-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 1,4- dioxane analytical methods used by Gelman or the state-funded program.

Will Hathaway, Scio Township Supervisor, has worked together with Scio Trustee Kathleen Knol to push for more data on the extent of the contamination and faster progress on the Gelman cleanup. Their efforts have included advocating for the Environmental Protection Agency (EPA) to become involved with the cleanup. The Township will continue to coordinate with WCHD and EGLE regarding future sampling efforts.

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 1,4-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 likely human carcinogen 1,4-dioxane. The 1,4-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 1,4-dioxane and the state-funded residential sampling program can be obtained at the webpage: 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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