Aidex Corporation ran a pesticide formulation facility on a 15-acre property near Mineola, Iowa from 1974 to 1980. Spills during material transfers, improper waste handling, and a 1976 building fire left soil and shallow groundwater contaminated with a wide range of pesticides and agricultural chemicals. Contaminants include aldrin, chlordane, chlorpyrifos, dieldrin, endrin, heptachlor, toxaphene, the herbicide atrazine, organophosphate insecticides such as disulfoton and phorate, pentachlorophenol, and nitrate/nitrite. These substances were found in soil, groundwater, and waste materials, and they threatened 42 domestic water wells within two miles of the site.
The EPA added the site to the National Priorities List (NPL) in September 1983 after an initial assessment in 1980. Cleanup was organized into separate operable units. The main remedial unit had a Record of Decision issued in September 1984 that called for excavating and disposing of over 20,600 cubic yards of contaminated soil and buried wastes, decontaminating buried tanks and waste pits, building a drainage system, and expanding the monitoring well network. A second unit addressed interim measures including offsite disposal, groundwater extraction, and drainage controls. The main remedial action ran from May 1986 to May 1987, and construction was completed in June 1992.
The EPA deleted the site from the NPL in October 1993 after the cleanup proved protective. A final Five-Year Review completed in January 2004 confirmed no further cleanup is needed. Human exposure is under control, with no unacceptable exposure pathways identified. Groundwater contamination has stabilized in its original area and is not spreading. Both the EPA and the state of Iowa determined that the work done protects public health and the environment.
The site is now actively reused. As of December 2024, three businesses operate there, employing 42 people and generating about $6.49 million in annual sales. Institutional controls limit certain land uses, such as residential development, to keep reuse compatible with the level of cleanup achieved. No additional sampling or monitoring is required.
Community members with questions can contact the EPA staff assigned to the site. The EPA's Superfund database also holds an administrative record of 84 documents, six Five-Year Review reports, and other publicly available materials for anyone wanting more detail on the site's history.
