Exposure Unit 002 (EU002) is located in Saginaw County, Michigan, and is contaminated with dioxins and furans that have or may have come to be located from The Dow Chemical Company Midland Plant property. Dow’s Midland facility is a 1,900-acre chemical manufacturing plant. Dioxins and furans are byproducts from the manufacture of chlorine-based products. Past waste disposal practices, emissions and incineration at Dow have resulted in on and off-site dioxin and furan contamination.
As part of Dow’s RCRA Remedial Investigation Work Plan(RIWP), several transects were placed across the Tittabawassee River to collect soil and sediment for analysis in 2007. Based on the analytical results, MDEQ identified several areas where sample results indicated that potential risk to public health may be present due to higher contaminant concentrations in residential or high public use areas.
In February, 2008, MDEQ, U.S. EPA, and MDCH met to evaluate data previously provided by Dow to determine the need to conduct further assessment of properties in the floodplain. The team determined that additional assessment, including sampling, would be necessary. The purpose of the sampling was to determine if there was substantial risk to those people accessing or living on the properties. During the discussions, it was decided that MDEQ would lead the effort to prioritize area to be further assessed.
EU002 is subject to periodic, almost annual, flooding and erosion. This is particularly true during high stream flow events. EU002 flooding results in the deposition of contaminated soil and sediment from upstream locations. This may result in an increase in the amount and/or level of dioxin contamination at EU002 in the future. Flooding and erosion of EU002 also may result in the spread of dioxin contamination to other locations within the flood plain, as well as to downstream locations.
The response actions will mitigate threats to public health, welfare, and the environment presented by the presence of an uncontrolled release of dioxin and furans (hazardous substances) that pose a high risk of direct contact to humans and wildlife in soils and dust located within the EU002.
The removal actions for the West Michigan Park area within EU002 include excavation and disposal of contaminated soil at the surface, excavation and/or containment of remaining contaminated soil below the excavated areas (if necessary), air monitoring, backfilling and restoration of the impacted areas, removal of highly contaminated soils from and paving of the West Michigan Park parking lot, replacement of playground equipment, and development of a post removal monitoring plan to ensure continued integrity of cleanup activities. Other areas within EU002 that have been identified as potential exposure pathways will be assessed and barrier control plans will be implemented to mitigate threats to public health, welfare, and the environment.
Excavation and disposal activities will be conducted in a manner as protective as possible of existing structures and to preserve mature trees. The response activities will require approximately 75 on-site working days to complete.
