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

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From Scio Township:

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. This sampling program has a detection limit of 1 ug/L (or part per billion).

Due to concerns about potential movement of the 1,4-dioxane plume to residential areas located north of M-14, Scio Township has completed two 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 1 location which had previous detections under the state-funded program and at two locations which had not been previously sampled and are below the state’s detection limit. 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. 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.

This most recent sampling identified four additional residences with low levels of 1,4-dioxane, all of which are located north of the estimated plume boundary. Three of these residences are located near the northernmost detection from the first round of sampling in an area southeast of the intersection of N. Wagner and Miller Roads. The levels of dioxane detected in the four residences ranged from 0.26 ug/L to 1.0 ug/L. These concentrations are below the State of Michigan drinking water standard for 1,4-dioxane of 7.2 ug/L. All other residences tested nondetect for 1,4-dioxane. The residents have all been informed of the sample results.

Will Hathaway, Scio Township Supervisor, 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. 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.

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