https://www.a2gov.org/departments/systems-planning/planning-areas/climate-sustainability/pls/Pages/timeline.aspx
1964 & 1967: Two lagoons built on Gelman property to receive waste from production process.
1966: Gelman began the use of 1,4 Dioxane in the manufacturing of medical filters.
1968: Water Resources Commission investigates complaints by local residents about foul odors emitted by the storage lagoons. Water samples taken and lagoon overflow into nearby marsh documented. Company found to be in violation of 1965 Order of Determination.
1965: 1,4 Dioxane (hereafter "Dioxane") first shown to be an animal carcinogen in scientific studies.
1960's, 70's, 80's: Complaints about odors were filed by neighboring residents and businesses.
1973: Gelman installed a three million gallon holding lagoon on its property, and began a new waste treatment process of spray irrigation, in which treated waste was sprayed onto the property.
1976 - 1985: Dioxane was used as a solvent by Gelman Science, Inc. ("Gelman") as part of its process of manufacturing filters for medical uses. The used Dioxane was dumped in unlined lagoons and sprayed onto soil, and began seeping into the ground. Gelman, now owned by Pall Life Sciences, is based at 600 Wagner Road, 2.5 miles west of downtown Ann Arbor.
1979: Gelman found to be in violation of its NPDES Industrial Wastewater permit.
1980: 1,4 Dioxane placed on Michigan's Critical Material Register. It has subsequently appeared on this list every year since. (Chemicals on this list are toxic, and businesses using them must report their usage to the state annually.)
Former Gelman employee notified DNR that one of Gelman's lagoons was leaking into the University of Michigan-owned Saginaw Forest. This employee also accused Gelman of illegally operating, and subsequently burying, a chemical pit.
Gelman reported using or storing 60,000 pounds of Dioxane annually.
Citizen complaint leads to discovery that Gelman was illegally discharging wastes from storage lagoon into a marsh on neighboring property via hose and pump.
July 1980-October 1982: maximum daily discharge limit allowed by permit was often exceeded. Limit of 112,700 gallons per day was sometimes exceeded by over 100,000 gallons. Nutrient levels were also reported to be exceeding permitted levels.
1981: DNR tests detected Dioxane in each of Gelman's three lagoons, at concentrations up to 25,000 parts per billion (ppb).
Gelman began contruction of a 6,500 foot underground injection well for the disposal of wastewater.
1982: Gelman began using the deep-injection well.
1983: The Gelman site was placed on the Michigan Sites of Environmental Contamination Priority List, which defines "where there has been a release, or where potential for release of a discarded hazardous toxic substance exists."
1984: University of Michigan School of Public Health graduate student Dan Bicknell discovered Dioxane in Third Sister Lake, located just west of the Gelman property, in the UM–owned Saginaw Forest. Subsequent tests of the tributary running from Gelman's property into the lake showed Dioxane in levels several times higher than those found in the lake, establishing Gelman as the source of the pollution.
Gelman paid for Dioxane tests by Canton Analytical Labs (CAL) and U-M researcher Clifford Rice. DNR and CAL test results did not reveal the presence of Dioxane. Gelman refuses to publish the results from Clifford Rice. Dr. Rice reported that his findings confirmed the presence of Dioxane in the lake.
1985: Dioxane contamination discovered by Washtenaw County Health Board in 30 water-supply wells north of the Gelman property.
Gelman site moved to 89th on the Priority List of contaminated sites.
Department of Public Health begins testing residents' wells after residents petition.
1986: Gelman began buying bottled water for businesses and agreed to help pay for extension of city water lines to affected subdivisions.
State of Michigan recommended 3 parts per billion (ppb) as a safe standard for drinking water.
Gelman Science, Inc. listed in '101 Best Performing Companies in America'
Gelman site moved to 2nd on the Priority List for contaminated sites.
Gelman stopped using 1,4 Dioxane and began hydrogeologic studies to assess the extent of contamination.
EPA issued a permit for a mile-deep injection well for disposal of contaminated groundwater. Residents opposed this plan.
1987: DNR report states: "Dioxane vapor is known to be harmful and a known lung and mucous membrane irritant."
Interview with Gene Hall, (DNR water quality specialist who investigated the Gelman contamination) reveals that DNR tests that were consistently negative for Dioxane were flawed, and that the DNR lab was unable to test for Dioxane.
1988: MI Attorney General, on behalf of the Dept. Of Natural Resources, filed suit against Gelman to force a cleanup of the groundwater.
1992: Lawsuit between state and Gelman settled: company agreed to pay state over $1 million in damages and begin a $4 million cleanup project. Plan would treat groundwater and drain it into a tributary of Honey Creek,and empties into the Huron River. PPM set for this cleanup?
1995: After another round of lawsuits, company agreed to dispose of treated wastewater on its own site via treatment and re-injection into a deep well. {people were upset by this idea}
1997: Pall Corporation bought Gelman Sciences and assumed liability for the cleanup. Became 'Pall Life Sciences', or PLS.
1997-2000: PLS applied to increase the allowable concentration of Dioxane in treated water and to double the amount of water it was discharging.
2000: Michigan Department of Environmental Quality (having assumed responsibility for pollution issues from the DNR) ruled that PLS could discharge 800 gallons per minute and increase its concentration of daily maximum of Dioxane to 60 ppb (parts per billion), but required the maintenance of the monthly average of 10 ppb.
July 2000: Judge Shelton ordered PLS to clean groundwater to within state acceptable levels within five years.
Contamination of the deepest aquifer, called the "Unit E" aquifer, was discovered. Unit E was previously thought to be uncontaminated.
Continuing high levels of Dioxane at several test wells, despite ongoing treatment of wastewater.
2001: Trace levels of 1,4 Dioxane discovered during a routine test of Ann Arbor's Montgomery well, which was used by the city as a winter water source. The well was not in use at the time and has been unused since this discovery. This well provided less than 5% of Ann Arbor's water.
City appeals decision by MDEQ to allow increase in discharge of groundwater into Honey Creek.
2002: Congressman John Dingell requests assistance from US Geological Survey to provide technical expertise on the hydrogeology of the contaminated aquifers in the city.
Feb. 2003: Ann Arbor City Council authorized City officials to take all appropriate legal action to protect the City's water from Dioxane contamination.
2003: PLS submitted a feasibility work plan to evaluate an 'in-situ' (in place) oxidation system using hydrogen peroxide and ozone to degrade dioxane in the aquifers without removing the groundwater.
As of Jan. 2004: PLS claims to have removed and treated over 2.2 billion gallons of groundwater and removed over 56,000 pounds of 1,4 Dioxane from the contaminated aquifers since 1997.
Current treatment system: removes 1300 gallons of water per minute from 18 wells, treats it with a combination of ultraviolet light and hydrogen peroxide, and drains into a Honey Creek tributary. Honey Creek flows into the Huron River, upstream of the Ann Arbor water supply intake at Barton Dam.
The current cleanup criteria is 85 ppb for groundwater, by 2005 under the Consent Order in Judge Shelton's Court. These criterion were established by MDEQ using a U.S. Environmental Protection Agency methodology.
As of February 2004: over 70 contaminated water-supply wells have been identified.