Wet Basement Testing for 1,4-Dioxane

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​​​​ 919 Sunset Road, Ann Arbor, MI 48103

8 a.m.-5 p.m.
(excluding holidays)

24/7 water emergency line



Molly Maciejewski,
Water Treatment Services Manager


​​​​In April 2020, City Council authorized funding to sample flooded basements for 1,4-dioxane in low-lying areas intersecting the Gelman plume. 

Project Status

Candidates were contacted directly via mail with project participation details in 2020. Test results are public record and were shared with Washtenaw County Health Department and the Michigan Department of Environment, Great Lakes and Energy. 

City of Ann Arbor_1,4 Dioxane Basement Sampling_Sample Locations (PDF)​

Informational​ Project Meeting 

The City of Ann Arbor held an informational meeting on Thursday, Sept. 10, 2020 to discuss how and when sampling will be conducted. The video of that meeting is now available via the Community Television Network's (CTN) ​YouTube page.  

Answers to Freq​uently Asked Questions

​Q: What is 1,4-dioxane and is it harmful?
A: It is a manmade compound that mixes easily in water. It is used in industry as a solvent to manufacture other chemicals and it is a by-product in many items, including paint strippers, dyes, greases, antifreeze and aircraft deicing fluids.  It is also found in other chemicals that are used to manufacture cosmetics, detergents, deodorants and shampoos.

The compound was detected at Gelman Sciences on Wagner Road in the 1980s.  It has been spreading west in Scio Township and northeast then east towards the Huron River. 1,4-dioxane is classified as 'possibly carcinogenic' to humans because it is a known carcinogen in other animals.

Q: Do I need my basement flood water sampled for 1,4-dioxane?
A: No, you do not have to have your basement sampled. If your basement floods and your home is located above the Gelman plume in the areas determined in a recent evaluation; you may request to have your basement sump sampled.  More information on how your home was selected and how samples will be collected will be available at the information meeting on September 10, 2020.

​Q: What do I do if my basement sample has detectable concentrations of 1,4-dioxane?
A: Washtenaw County Health Department will be contacted if there are detectable concentrations of 1,4-dioxane in the sump water. 

Q: Where can I find more information on 1,4-dioxane?
: Read the Washtenaw County Health Department Fact Sheet on 1,4-dioxane (PDF) or the State of ​Michigan Department of Health and Human Services fact sheet (PDF)​. The city also provides quarterly updates: 1st Quarter Gelman Plume Update (PDF)​ - April 2021​

Q: What if my basement doesn't flood and I live over the plume?  Should I be concerned?
A: No, the 1,4-dioxane in Ann Arbor is present in groundwater.  If your home does not flood, you will not be in contact with the groundwater plume.  

Q: Who will be sampling my basement and what protections will I have against Coronavirus?
A: The City of Ann Arbor has hired Tetra Tech, a consulting firm, to sample the flood waters.  They will put on new personal protective equipment outside of your home before entering. This includes a face mask, protective safety glasses, gloves and shoe protectors.  The sampling team will reduce their time in your home by completing as much paperwork as possible outside.

Q: In addition to the sampling, what additional activities will Tetra Tech be completing in my home?
A: Tetra Tech staff will complete a checklist of the basement area to document potential household sources of 1,4-dioxane, the presence and location of a basement sump, type of flooring, any visible staining, and any other information pertinent to the collection of a water sample. If permitted by the homeowner, the flooded conditions will be documented with photographs. The sampling and documentation procedures will take approximately 15 to 30 minutes to complete.

​Q: When will I receive the test results?
A: Letter reports will be sent to homeowners and City of Ann Arbor personnel approximately four weeks after the sample is delivered to the laboratory.  Tetra Tech will provide the homeowner with a letter that contains the laboratory results, sampling checklist and notes completed during the site visit.

​Q: Will the test results be made public?
A: Yes, the test results will become part of the public record and will be shared with Washtenaw County Health Department and the Michigan Department of Environment, Great Lakes and Energy.
City of Ann Arbor_1,4 Dioxane Basement Sampling_Sample Locations (PDF)​


Questions and comments can be emailed to [email protected] or call 734.213.4069.