TITTABAWASSEE RIVER, SAGINAW RIVER & BAY
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The Dow Chemical Company facility in Midland, Michigan, began operating in 1897. The 1,900-acre facility abuts the Tittabawassee River; most of the plant is located on the east side of the river and south of the city of Midland. At various times, the Midland Plant produced over 1,000 different organic and inorganic chemicals. Dioxins and furans were byproducts formed during the manufacture of chlorine-based products, including chlorophenolic compounds manufactured at the plant since the 1930s. Elevated dioxin levels in and along the Tittabawassee River and downstream appear to be primarily attributable to liquid wastes that were discharged in the past directly into the river from the facility.
Past waste disposal practices at the Midland Plant have resulted in on and off-site contamination that settled in some sediment and built up in some riverbanks and floodplain areas. Off-site contamination extends over 50 miles downstream through the Tittabawassee and Saginaw Rivers and into Saginaw Bay.
What Has Been Done to Clean Up the Site?
EPA selected cleanups have been underway for several years. Dow is implementing these actions with EPA oversight. To manage the cleanups, EPA divided the Tittabawassee River into seven segments ranging in length from three to four miles. Work is being done in stages from upstream to downstream, segment by segment. Cleanups target specific areas in each segment called Sediment Management Areas, or SMAs, and Bank Management Areas, or BMAs.
Segment 1, a 3-mile stretch next to the Midland Plant, is the most upstream segment. Cleanup started in 2012 and finished in 2013. The Segment 1 cleanup removed and treated dense non-aqueous phase liquid (DNAPL). A containment system was installed at five SMAs in Segment 1 to isolate contaminated sediment. Since 2013, the area is monitored and containment systems are maintained.
Segment 2 is a four-mile stretch of the river below the Midland Plant. The cleanup plan built on previous work, removing contaminated sediment in some areas and stabilizing contamination to stop it from moving in others. Nearly 23,000 cubic yards of contaminated sediment was removed and about 2.3 acres of contaminated sediment was isolated and contained. Close to a mile of riverbank was stabilized to keep eroding contaminated soil from washing back into the river.
Segment 3 is a four-mile stretch of the river that starts about seven miles below where the Chippewa River meets the Tittabawassee River. The Segment 3 cleanup included stabilization of about 1.2 miles of eroding BMAs. Many different stabilization technologies were used on the BMAs. One of the most important elements is the use of deep-rooted native plants, placed along the riverbanks. Two SMAs were cleaned by a combination of digging up contaminated sediment in dry conditions and removing it, and covering contaminated sediment to keep it safely in place.
Segments 4 and 5 consist of a 6-mile stretch of the river that starts about 11 ½ miles downstream of the Dow Chemical Co. plant in Midland. EPA selected a cleanup plan for the Segments 4 and 5 of the Tittabawassee River in early 2017. Like the upstream segments, there are distinct SMAs and BMAs in Segments 4 and 5. A combination of technologies are being implemented for the SMAs, including digging up and removing some contaminated sediment, safely covering other areas, and monitoring areas where contamination is already buried. Cleanup technologies that stabilize BMAs and stop erosion of contaminated riverbank soil are being applied as well. Work in Segment 4 was largely completed in 2017, while the Segment 5 sediment and bank cleanups is ongoing in 2018.
Segments 6 and 7 consist of a 6.7 mile stretch of the river that starts about 17.7 miles downstream of the Dow Chemical Co. plant in Midland. EPA is currently developing a plan for Segments 6 and 7 which will propose cleanups for 7 BMAs and 4 SMAs. EPA will build on lessons learned from upstream segments.
Tittabawassee River Floodplain:
EPA selected a cleanup plan for contaminated soil in frequently flooded areas along the Tittabawassee River in 2015, and the multi-year floodplain cleanup started that same year. Many properties in the Tittabawassee River floodplain will be evaluated for cleanup. The floodplain includes about 4,500 acres and extends along 21 miles of the river below Dow’s plant in Midland. EPA's floodplain cleanup will protect all people who live, work and play along the Tittabawassee River. Not all areas in the floodplain will need a cleanup. Because floodplain land is used in different ways, EPA’s plan uses a combination of steps. In homeowners' yards that are maintained for typical backyard uses, if tests show a contamination level greater than 250 parts of dioxin in a trillion parts of soil – or ppt – soil will be dug up and hauled away. Soil will be replaced and grasses and plants restored. For other areas such as farms, parks, commercial properties and natural areas, if tests show a contamination level greater than 2,000 ppt, soil will either be dug up and hauled away or covered with clean soil. EPA will work with each property owner on the right approach and after cleanup, these areas will be replanted. The pace of floodplain cleanup has increased every year, and the project will likely extend through 2020 or 2021.
What Is the Current Site Status?
EPA expects to release a plan in fall 2018 that proposes cleanup options for Segments 6 and 7. In 2018, construction occurred in and along Segments 4 &5, with construction coming to a halt in early November. Two Bank Managements Areas (BMA) in Segment 4 and nine BMAs in Segment 5 were completed in 2018, with one BMA in Segment 5 to be completed in 2019. One Sediment Management Area (SMA) in Segment 5 was completed, with one remaining for 2019. Over the course of Spring 2019, EPA plans to inspect and evaluate all previously constructed areas and determine which areas need maintenance. Check back later for more details.