Mid-America Tanning Co. operated as a leather tannery on a 100-acre site near Sergeant Bluff, Iowa, from 1970 to 1989. The facility used a chrome tanning process starting in 1973, which produced chromium-rich sludge that workers buried in unlined on-site trenches or spread on soils. When operations stopped, roughly 5,000 gallons of chromium tanning solution and about 525 gallons of sulfuric acid were left on the property. The EPA added the site to the Superfund National Priorities List (NPL) in 1989 because of imminent health threats. The main risks came from people ingesting or touching contaminants in soil, sludge, and water in the lagoons.
Chromium and lead are the contaminants of concern. They were found in groundwater, sediment, soil, and surface water. Cleanup was organized into two operable units. Operable Unit 1 covered surface remediation. A removal action in 1990 excavated contaminated sludge and contained liquid wastes. A formal cleanup plan issued in September 1991 called for on-site stabilization, soil capping, and groundwater monitoring. After workers discovered potential hydrogen sulfide gas, an amended plan in 1996 added dewatering, soil excavation, capping, and building decontamination. Remedial action construction ran from September 1998 through September 2000. In 2005, roughly 100,000 gallons of waste and 50,000 gallons of hydrogen sulfide-containing material released from a 10-inch pipe near the burial area. The pipe was plugged and capped, and the EPA completed additional containment work in June 2007.
The site was deleted from the NPL in September 2004. Human exposure pathways are no longer unacceptable, groundwater migration has been stabilized, and all cleanup goals for current and reasonably anticipated future land uses have been met. Groundwater is not used as a drinking water source in the area. The Iowa Department of Natural Resources now handles ongoing operation and maintenance. Deed restrictions keep land use non-residential, and the current owner uses the property for tree debris storage.
The most recent Five-Year Review, completed in August 2023, confirmed that response actions continue to protect human health and the environment. The next review is scheduled between August and October 2028. Community members can review site documents, including the Record of Decision and five-year review reports, through the EPA's records system. Questions can be directed to the EPA staff assigned to the site or the Iowa Department of Natural Resources.
