Cornhusker Army Ammunition Plant covers 12,042 acres near Grand Island in Hall County, Nebraska. Built in 1942 to produce munitions during World War II, the plant contaminated groundwater both on the property and beyond its boundaries through improper wastewater disposal and other industrial processes. The site was added to the National Priorities List in 1987 and has been undergoing cleanup across five operable units since 1989. About 97 percent of the property has been sold to private buyers for agriculture, recreation, industry, and other uses, though residential development is restricted in contaminated areas.
The main contamination concern is an explosives groundwater plume containing TNT, RDX, and HMX, along with breakdown products such as 2,4-dinitrotoluene and various nitrobenzenes. The groundwater also holds metals including arsenic, cadmium, lead, mercury, and nickel, plus volatile organic compounds like dichloromethane and chlorinated solvents. Additional contaminants include nitrate, nitrite, sulfate, and fluorene. The U.S. Army Corps of Engineers is leading cleanup under a 1990 Interagency Agreement with EPA and the Nebraska Department of Water, Energy, and Environment.
The current groundwater remedy relies on monitored natural attenuation. Since December 2006, the Army has been injecting nutrients into the aquifer to speed up natural breakdown of contaminants. A trial shutdown of the groundwater extraction and treatment system in 2019 was deemed successful, and the system remained off as of 2022. Contaminated soils in other areas are handled through excavation and offsite disposal. Institutional controls restrict drinking water well drilling in affected zones, prohibit residential development in contaminated areas, and require deed restrictions on three of the five operable units. The city provides municipal water to all impacted residents.
EPA has determined that human exposure is under control and that groundwater migration is stabilized with no unacceptable discharge to surface water. Residents have used public water supplies since the early 1990s, and there are no known exposures to contaminants at harmful levels. Physical construction of the cleanup is not yet complete for the entire site. A Record of Decision Amendment is expected to be available for public comment in June 2026. The Five-Year Review evaluating remedy effectiveness is due by June 10, 2026, and the most recent five-year review was completed in September 2025.
Community members can stay informed by attending annual public meetings each November at the CHAAP Groundwater Treatment Plant. Public notices for those meetings are published in the Grand Island Independent at least 30 days in advance. Groundwater monitoring data are collected every December and annual reports are posted on the CHAAP website. Questions can be directed to EPA's Community Involvement Coordinator Shaylee Borcsani, Remedial Project Manager Haley Hart, or Nancy Harris at the Nebraska Department of Water, Energy, and Environment. The complete Administrative Record is available at the Grand Island Public Library, 1124 W 2nd Street, Grand Island, NE 68801.
