Twin Cities Army Ammunition Plant

The Twin Cities Army Ammunition Plant (TCAAP) is a former United States Army manufacturing installation located in the New Brighton and Arden Hills area of Ramsey County, Minnesota, in the northern part of the Minneapolis-St. Paul metropolitan area. Construction began in 1941, and the plant started producing small-caliber ammunition, including .30 caliber, .50 caliber, and .45 automatic rounds, in March 1942. Over the following decades the facility operated in cycles tied to wartime demand, with major production periods during World War II, the Korean War, and the Vietnam era, and it later expanded into artillery shell components and other military hardware. The plant was placed on standby in the late 1970s and was formally closed in the years that followed, with much of the property eventually slated for redevelopment. The broader Superfund site, often referenced as the New Brighton/Arden Hills/TCAAP site, covers a large area and includes off-site groundwater plumes affecting several surrounding communities.

Decades of munitions production, waste disposal, and solvent use at the installation have been associated with contamination of soil, sediment, surface water, and groundwater. Investigations by federal and state agencies have documented a range of substances at the site, and concerns about potential exposure have centered on both on-site conditions and contaminated groundwater that migrated beyond the original plant boundary.

1. TCE (trichloroethylene) is an industrial solvent often used to degrease metal parts. At this plant, waste solvents were disposed of into the ground, a common practice at the time, and TCE was identified in 1981 in municipal, mobile home park, and private wells in the vicinity at levels reported from a few parts per billion to over two hundred parts per billion. Exposure to TCE has been associated with a range of health concerns in scientific and regulatory literature.
2. PCE (tetrachloroethylene) and other volatile organic compounds were also documented among the solvents linked to the site. These compounds were used in industrial cleaning and degreasing operations, and their presence in groundwater has prompted concerns about potential exposure through drinking water.
3. PCBs (polychlorinated biphenyls) are a group of synthetic chemicals once used in electrical equipment, hydraulic systems, and various industrial applications. PCBs were among the contaminants identified in soil and sediment at the installation, and concerns about potential long-term exposure have been noted in environmental assessments of the site.
4. Heavy metals, including metals associated with ammunition manufacturing, were documented in soil, sediment, and water at the plant. Persistent metals can remain in the environment for long periods, and exposure has been associated with potential health effects depending on the metal and the level and duration of contact.
5. Explosives and related compounds were documented at the site as byproducts of munitions production and handling. Along with cyanide and pesticides also identified at the installation, these substances contributed to the contamination that prompted federal oversight and ongoing investigation of potential exposure pathways.

The New Brighton/Arden Hills/TCAAP site was added to the EPA National Priorities List in 1983, making it one of the largest Superfund sites in Minnesota. Since then, the Army, the EPA, the Minnesota Pollution Control Agency, and the Minnesota Department of Health have carried out extensive investigation and remediation, including groundwater treatment and water supply measures for affected communities. The EPA has reported that portions of the site were deleted from the National Priorities List as cleanup milestones were reached, while remediation and monitoring have continued at other areas.

Veterans, civilian workers, and family members who spent time at or near the Twin Cities Army Ammunition Plant may wish to stay informed about the ongoing cleanup and the substances documented there. Those with questions about possible exposure are encouraged to keep records of their service and to consult the U.S. Department of Veterans Affairs and their own healthcare providers regarding any individual health concerns.