Important Updates

1,4-dioxane detected in City of Ann Arbor drinking water

A water sample collected on February 6, 2019 indicated an almost undetectable amount of 1,4-dioxane in the city’s surface water supply (Huron River) and in the finished drinking water. The results estimated concentrations of 0.061 parts per billion (ppb) of 1,4-dioxane at the city’s intake in Barton Pond and 0.030 ppb in the finished drinking water.

There have been no additional 1,4-dioxane detections in the City of Ann Arbor’s municipal water.

Michigan Department of Environmental Quality Press Release

February 7, 2019: MDEQ to oversee sampling of Allen Creek storm drain as part of Gelman investigation 

Washtenaw County Water Resources Commissioner’s Office Press Release

November 20, 2018: 1,4-Dioxane Detected in Storm Sewer 

Recommendations for Updating Michigan’s Generic Cleanup Criteria 

View the recommendations.

The Michigan Department of Environmental Quality (DEQ) is Proposing a Part 201 Rule Amendment Specifically for 1,4-Dioxane

The DEQ is proposing an amendment to the Cleanup Criteria Requirements for Response Activity Rules, commonly known as the Part 201 Rules, for a single hazardous substance: 1,4-dioxane. This rule amendment will modify the cleanup criterion for 1,4-dioxane for the residential drinking water pathway only. The DEQ issued an Emergency Rule on October 27, 2016 that established the 1,4-dioxane cleanup criterion for the residential drinking water ingestion pathway at 7.2 parts per billion, with the expectation that a comprehensive update to the Part 201 Rules for over 300 hazardous substances would be completed before the Emergency Rule expired.

Due to the impending expiration of the Emergency Rule and the anticipated timeline for the comprehensive Part 201 Rule amendment package, the DEQ has decided to move forward with the 1,4-dioxane amendment.

CARD Adopts Bylaws and Elects Officers

At the April 4, 2017 meeting CARD adopted bylaws and elected its first officers. 

Congratulations to Chair Roger Rayle, Vice Chair Mike Moran, Secretary Shana Milkie and Treasurer Vince Caruso! The officers elected Jennifer Conn to be CARD’s executive director.

USEPA Region 5 staff presented about the Superfund Program 

The presentation was at the Ann Arbor Environmental Commission meeting on Thursday, January 26, 2017. 

Dr. Detlef Knappe’s research seminar "1,4-Dioxane in the Cape Fear River Watershed of North Carolina" from January 2017 at the University of Michigan’s School of Public Health has been posted by the Michigan Public Health Training Center and is free to view after a free registration.

City of Ann Arbor, Washtenaw County and the Huron River Watershed Council Motions to Intervene Granted

On December 15, 2016 Judge Connors granted the City of Ann Arbor, Washtenaw County Public Health and the Huron River Watershed Council Motions to Intervene as plaintiffs in the lawsuit against Gelman Sciences, Inc. The three parties will now join the State of Michigan in future discussions and agreements regarding the 1,4-dioxane contamination.

October 27, 2016 Townhall Meeting

The meeting was organized by Ann Arbor Councilman Chuck Warpehoski and was intended to answer resident questions regarding the 1,4-dioxane plume and the August 2016 Shallow Groundwater Investigation.

Not all submitted questions were answered during the meeting due to lack of time, therefore the Michigan Department of Environmental Quality (MDEQ) and Michigan Department of Health and Human Services (MDHHS) committed to providing written answers to all of the questions. 

News Release from the Michigan Department of Environmental Quality: MDEQ Issues Emergency Rules on 1,4-Dioxane

October 27, 2016

The Michigan Department of Environmental Quality (MDEQ) today issued the following statement by MDEQ director C. Heidi Grether regarding the issuance of emergency rules to establish 1,4-dioxane standards across the state.

“We are issuing emergency rules to ensure we are protecting Michigan residents relative to 1,4-dioxane contamination in groundwater in Ann Arbor and elsewhere in Michigan. This is a precautionary move but we are particularly concerned about the potential of vapor intrusion in residences. Our recent testing of shallow groundwater in Ann Arbor confirms the presence of contamination a significant distance from the heart of the plume. While there is no acute threat at this time, issuing these emergency rules is the responsible thing to do as we seek to put public health first and foremost in everything we do.”

Rule 1. The residential drinking water cleanup criterion for 1,4-dioxane in groundwater is 7.2 parts per billion.

Rule 2. The residential vapor intrusion screening criterion for 1,4-dioxane is 29 parts per billion.

Please click here for a copy of the emergency rules.

News Release from the Michigan Department of Environmental Quality: MDEQ Proposes Tougher Drinking Water Standards to Protect Residents from 1,4-Dioxane

March 14, 2016

The Michigan Department of Environmental Quality is proposing to strengthen the drinking water clean-up standard for 1,4-Dioxane by a factor of 10 in a new rules package under consideration by the agency. The more protective standard is based on new calculations completed by the DEQ using a science-based process, including current EPA toxicity data and Michigan-specific exposure factors. The new rule would change the 1,4-Dioxane drinking water standard in Michigan from 85 parts per billion (ppb) to 7.2 ppb.

The chemical 1,4-Dioxane is an industrial solvent that has been linked to human health concerns at certain concentrations given long-term exposure. The proposed change would affect contaminated sites across the state where 1,4-Dioxane has been shown to be present. The DEQ and the citizens of the City of Ann Arbor have been focused on the standard as it pertains to the Pall-Gelman contaminant plume. The Pall-Gelman 1,4-Dioxane plume has contaminated three square miles of groundwater below the City of Ann Arbor.

The plume has not affected the City of Ann Arbor’s drinking water supply. One Scio Township resident’s well water had 1,4-Dioxane levels greater than Michigan’s new proposed standard. That home has been connected to the city’s water supply. Gov. Rick Snyder’s proposed Fiscal Year 2017 budget includes an additional $700,000 for addressing the Pall-Gelman1,4-Dioxane plume.

“The DEQ’s first priority is to protect public health,” said DEQ Director Keith Creagh. “This revised standard strengthens those protections for all Michiganders. The DEQ is committed to open communications and transparency of our actions in affected communities. We will work with local stakeholders to ensure residents are informed and supported.”

Creagh will take part in a town hall meeting hosted by Rep. Jeff Irwin of Ann Arbor. The event will take place 6 p.m. Monday, April 18, in the auditorium of the Eberwhite Elementary School, 800 Soule Boulevard, Ann Arbor.

“The Ann Arbor community and its leaders have been great partners in addressing this issue, and we look forward to continuing to work with them on addressing the Pall-Gelman plume,” Creagh said.

The calculation of the 1,4-Dioxane criteria is part of a major effort by the DEQ to update the criteria for 308 hazardous substances used to determine cleanup standards across the state. The new state standard assumes an exposure period of 32 years at the level of 7.2 ppb to protect public health.

The Michigan standard will be an enforceable standard. It is based upon the same toxicity level as the U.S. Environmental Protection Agency screening level. However, the federal screening level of 3.5 ppb – which is not enforceable -- assumes an exposure period of 70 years. The state standard assumes an exposure period of 32 years to provide a more realistic assumption of risk and greater protections for the public. The Michigan standard will be among the most protective state standards in the country.

The DEQ’s process for updating these standards uses the latest, scientific information from reliable sources as well as Michigan-specific exposure scenarios to ensure the protection of public health, safety and welfare for all Michigan citizens.

“We are in the process of finalizing the update for the cleanup standards for all hazardous substances and their exposure routes and will be releasing all of the proposed standards in April,” said DEQ Remediation and Redevelopment Chief Bob Wagner. “Review of the proposed rules will involve the Legislature as well as provide opportunity for public comment. We plan to finalize the rules as soon as possible with appropriate reviews.”

Michigan’s Department of Environmental Quality Reaches Settlement with Pall Corporation

On July 1, 2014, a settlement was filed in Washtenaw County Circuit Court between the Michigan Department of Environmental Quality (DEQ) and Pall Corporation. Pall Corporation is to pay $500,000 to cover past monitoring costs and clean-up oversight to the DEQ. For more information read the article here.

Dispute Resolution (Petition for Dispute Resolution) Hearing on the Western Area Monitoring Plan

This was heard on Wednesday, January 11, 2012 at 1:30 PM, at 101 E. Huron Street, second floor, Ann Arbor, in the court room of the Honorable Donald E. Shelton.

Honorable Judge Shelton ruled for Gelman Sciences d/b/a PALL Life Sciences, Inc.’s (Defendant) at the hearing "without prejudice" . The ruling allows for the DEQ to still rejoin the issue with better supporting documentation. The outcome of the ruling is that Gelman/Pall Life Sciences will not be required to install additional compliance monitoring wells, as requested by the MDEQ. The proposed additional compliance monitoring wells were to be installed at proper depths and closer to the known plume(s) at the core area, to aid in determining if the Consent Judgement requirement of non-expansion is achieved.

Also available for review is the Plaintiff’s Brief in Response to Defendant’s Petition for Dispute Resolution.

Below is the text of of the Press Release by the DNRE regarding Amendments to the Consent Judgment governing the cleanup of the PALL/Gelman site of 1,4-dioxane contamination.


Contact: Brad Wurfe, 517-373-7917

March 9, 2011 

Court revises cleanup plan for Ann Arbor site

The Michigan Department of Natural Resources and Environment today announced an agreement with a Washtenaw County company, amending cleanup requirements for a widespread plume of contaminated groundwater in Ann Arbor.

Washtenaw County Circuit Court Judge Donald Shelton ordered the change for Pall Life Sciences, successor to Gelman Sciences, amending of the plan to address groundwater contaminated with 1,4-dioxane.

The Gelman Sciences property, located on Wagner Road just south of Jackson Road in Scio Township, manufactured medical filters. Dioxane used at the plant from 1966 to 1986 was disposed of by various methods, resulting in widespread groundwater contamination in portions of the city of Ann Arbor, Scio and Ann Arbor Townships.

The first contaminated private water supply well was discovered in 1985. Since then, more than 120 contaminated private wells have been replaced with municipal water. Pall Life Sciences acquired the property from its original owner in 1997 and undertook responsibility for continuing the cleanup efforts.

The court has worked with Pall Life Sciences and the MDNRE since December 2008 to identify needed modifications to its 1992 judgment, and to further address disputes that arose when the MDNRE denied a May 2009 proposal by Pall Life Sciences to modify cleanup obligations in the judgment. Today’s action resolves those disputes.

The amendment divides the site into two main areas – west and east of Wagner Road (see map - link provided below as Attachment E) and amends specific cleanup obligations for these areas. It reflects changes made to the state cleanup law in 1995, which allowed for the initial court-ordered restrictions in 2005 on groundwater use in portions of Ann Arbor known as the Prohibition Zone.

Key components of the amendment include:

  • Court-approved expansion of the Prohibition Zone to the north of the current boundary into the Evergreen Subdivision area in Ann Arbor to restrict use of the groundwater.
  • Installation of additional groundwater monitoring wells by Pall Life Sciences to define and monitor the plume.
  • Continued groundwater extraction by Pall Life Sciences at several locations at a reduced rate (from 1,100 to 750 gallons per minute), along with treatment and discharge to the Honey Creek tributary, with termination of extraction subject to MDNRE approval.
  • Continued monitoring by Pall Life Sciences of groundwater contaminated with 1,4-dioxane that exceeds the generic residential cleanup criterion of 85 parts per billion until Pall Life Sciences can demonstrate the remaining groundwater contamination does not pose an unacceptable risk to human health, safety, welfare or the environment, now or in the future.

The MDNRE will host a March 30 public meeting in Ann Arbor to discuss the cleanup effort and answer questions about the court order. The meeting begins at 7 p.m. at the Abbot Elementary School, 2670 Sequoia Parkway.

For more information about this site, go to the MDNRE Remediation Division Web site at, scroll to “Sites of Interest” under “Contaminated Site Information” and click on “Gelman Sciences.” The amendment can be found under “Legal Documents.”

Links to the specific document related to the Third Amendment to Consent Judgment signed by Judge Donald Shelton, Washtenaw County Circuit Court

Stipulated Order Amending Previous Remediation Orders
Third Amendment to Consent Judgment (final, without signatures)
Attachment A

Attachment B [B-1 and B-2]

Attachment C

Attachment D (not part of 3rd Amendment)

Attachment E

Attachment F

Attachment G

Attachment H

Attachment I

US EPA IRIS Report on 1,4-dioxane Human Health Assessment

The Environmental Protection Agency (EPA) August 11, 2010, published the Integrated Risk Information System assessment for 1,4 dioxane. This assessment developed a revised cancer slope factor, which is used in the calculation of various cleanup and drinking water related criteria.

Carcinogenicity Assessment for Lifetime Exposure

Weight-of-Evidence Characterization:

  • Likely to be carcinogenic to humans

Weight-of-Evidence Narrative:

  • In accordance with the Guidelines for Carcinogen Risk Assessment (U.S. EPA, 2005, 1,4-dioxane is characterized as "likely to be carcinogenic to humans."
  • This may be a synopsis of the full weight-of-evidence narrative.

Quantitative Estimate of Carcinogenic Risk from Oral Exposure

Risk LevelLower Bound on
Concentration Estimate*

E-4 (1 in 10,000)

35 μg/L

E-5 (1 in 100,000)

3.5 μg/L

E-6 (1 in 1,000,000)

0.35 μg/L

*The unit risk and concentration estimates assume water consumption of 2 L/day by a 70 kg human.

Quantitative Estimate of Carcinogenic Risk from Inhalation Exposure

  • Information reviewed but value not estimated.

1,4-Dioxane included on Final EPA Contaminant Candidate List 3

The EPA has finalized the list of chemicals to be included in the Contaminant Candidate List 3 (CCL 3), which identifies contaminants that are currently not subject to any proposed or promulgated national primary drinking water regulations, that are known or anticipated to occur in public water systems, and which may require regulation under the Safe Drinking Water Act (SDWA). The list includes, among others, pesticides, disinfection byproducts, chemicals used in commerce, waterborne pathogens, pharmaceuticals, and biological toxins. The EPA uses a multi-step process to select 116 candidates for the final CCL 3. The final CCL 3 includes 104 chemicals or chemical groups and 12 microbiological contaminants.

Past Events:

On 6-15-2009, MDEQ denied Pall/Gelman’s (PLS’s) 5-4-2009 proposal to reduce its dioxane groundwater cleanup activities and risk polluting more area water supplies, including Barton Pond where Ann Arbor gets 80% of its water.

On May 4, 2009, PALL submitted the "Comprehensive Proposal to Modify Cleanup Program" at the former Gelman site, now owned by PALL. 

Pall Corporation (PALL) and the Michigan Department of Environmental Quality are required to adhere to the schedule contained in the April 22, 2009, Stipulated Order which modified the previous April 6, 2009 Order.

While the Washtenaw County Circuit Court (Court) is not supporting the public comment period that MDEQ requested, the MDEQ is making one available, albeit much shorter (4 weeks).

A main concern is that PLS is interested in expanding the prohibition zone to include the Evergreen area, eliminating the Consent Order requirement to clean up to 85 there and instead allowing up to 2800 ppb of 1,4-dioxane to migrate further downgradient.

Currently, there is very little geologic or hydrogeologic information to the north of the "evergreen plume" (Dexter-Ann Arbor Rd. area west of Maple Rd. and east of M-14) and no demonstration that expanding the prohibition zone toward Barton Pond will have no detrimental effects at Barton. Ann Arbors drinking water comes from a combination of sources. Eighty-five percent is drawn from the Huron River in Barton Pond. The remainder comes from groundwater wells located on the south side of town.

The concern of those close to the issue is that the Court took the Groundwater Surface Water Interface standard (2800ppb) and "dragged" it back from the Huron River to Maple Road with very little information demonstrating that the plume would head only to the east. It is unclear whether the Court is willing (or MDEQ will be effective in arguing) to "drag" the 34 ppb standard for a drinking water source back to the northern boundary of the prohibition zone.

Key issues related to the the revised "global" remediation strategy are the current lack of demonstration that there is no northerly flow (toward Barton Pond) prior to allowing this and what is the contingency plan if/when something goes wrong. The current proposal by PALL does not include a contingency plan.