The Olin Corp. McIntosh Plant sits one mile east-southeast of McIntosh, Alabama, along the Tombigbee River. Olin ran a mercury-cell chlor-alkali plant and a pesticide production plant there from 1952 to 1982. Those operations left behind contaminated groundwater, soil, sediment, surface water, and wildlife. The EPA added the site to the Superfund National Priorities List in 1984.
Contaminants found at the site include mercury, hexachlorobenzene (HCB), DDT and its breakdown products, and a range of chlorinated benzenes such as benzene, chlorobenzene, and 1,2,4-trichlorobenzene. Heavy metals including arsenic, cadmium, chromium, lead, and nickel have been detected in groundwater. Mercury, HCB, and DDT compounds have been found in fish tissue, sediment, surface water, and soil in the floodplain along the Tombigbee River. The Alabama Department of Public Health has issued a fish consumption advisory for that stretch of the river, recommending that people, including children and pregnant women, limit largemouth bass meals to two per month.
Cleanup is divided into two operable units. The main plant area, called OU-1, had a groundwater extraction and treatment system running from 2001 to 2017. As of 2023, regulators told Olin that groundwater has not yet met cleanup standards and more source characterization work is required. For OU-2, which covers the Olin Basin, the floodplain, and a wastewater ditch, the EPA finalized an amended cleanup plan in May 2024. That plan calls for an engineered sediment cap over the basin, in-situ stabilization of soils and sediments in the wastewater ditch at an estimated cost of $12.4 million, and an engineered multi-layer cap over the floodplain at an estimated cost of $26.3 million. Final remedial action in the floodplain area is estimated to begin between March and May 2027. Three businesses currently operate on parts of the site, employing about 225 people and generating roughly $433 million in annual sales. Institutional controls limit land use to industrial purposes and prohibit use of alluvial aquifer groundwater as drinking water.
The most recent five-year review was completed on August 31, 2021, and the next is estimated for August through October 2026. Construction cleanup is not yet complete, and the site has not been deleted from the National Priorities List. Community members can review the Administrative Record at the McIntosh Public Library at 83 Olin Road in McIntosh, Alabama. The EPA also accepts public input through notices, meetings, and interviews. The Responsiveness Summary in Appendix I of the 2024 amended cleanup decision addresses community questions about the selected remedy.
