Gelman Sciences Dioxane Project;
Ann Arbor, MI

Western System

HISTORY
Contamination was discovered in 1986. The installation of eight monitoring wells in 2000 revealed a geology that varied considerably. Primarily the contamination is in the Unit D0 aquifer. The contamination in the D0 aquifer is not directly connected to the contamination in the other aquifers. The contamination is being attributed to the high levels of 1,4-dioxane that was released to the Honey Creek Tributary in prior years.

LOCATION
The Consent Judgment defines the Western System as any groundwater contamination northwest, west or southwest of the Core Area.

CURRENT STATUS
In April 2002 PLS submitted a groundwater model and report demonstrating that generic residential cleanup criterion would be achieved naturally by July 2005. To date the Michigan Department of Environmental Quality has not accepted the conclusions in the report. PLS has since installed an extraction well northwest of Little Lake. This well is to be used if the results from monitoring do not reflect the trend predicted by PLS. Levels of 1,4-dioxane have been monitored and a slight increase has been seen in the well. PLS has implemented a contingency plan of batch purging from the extraction well in February 2003. Levels of 1,4-dioxane in the monitoring well have decreased since that time. Batch purging is done once a month. 30,000 Gallons are purged and trucked to the PLS site and treated.

If the Michigan Department of Environmental Quality makes the determination that generic residential cleanup criterion cannot be reached by July 2005 further remediation will be required. When the generic residential cleanup criterion is reached continued monitoring will take place for ten years to ensure that the level of 1,4-dioxane do not exceed the criterion.

Unit C3 (Core Area)
Unit D0 (Western System)
Unit D2 (Evergreen System)
Unit E Aquifer