Superfund Information Systems: Site Profile

Superfund Site:


Cleanup Activities

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The New Brighton/Arden Hills/TCAAP site consists of the Twin Cities Army Ammunition Plant (TCAAP) and parts of surrounding communities affected by contaminants from the plant. Waste dumped at 14 locations within TCAAP between 1941 and 1981 led to soil, sediment and groundwater contamination. The site’s total area, including off-site contaminated groundwater plumes, is about 25 square miles. Following immediate actions to protect human health and the environment, site cleanup and monitoring are ongoing.

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What Has Been Done to Clean Up the Site?

The U.S. Army is the party responsible for the site’s cleanup. The site is being addressed through federal and state actions in accordance with the 1987 TCAAP Federal Facility Agreement.

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What Is the Current Site Status?


U.S. Environmental Protection Agency (EPA) has proposed removing part of the New Brighton/Arden Hills/Twin Cities Army Ammunition Plant (TCAAP) Superfund site from the National Priorities List (NPL). The U.S. Army has completed the cleanup of about 2,400 acres of contaminated soil onsite. The 25-square mile site includes the former munitions plant and parts of surrounding communities.

The Army continues to clean up a plume of contaminated groundwater onsite. From 1941-1981, the Army dumped waste from the plant at 14 locations contaminating soil, sediment and groundwater. 
EPA’s 30-day public comment period began July 23 and closes Aug. 22, 2019. The public may submit comments three ways:

In 1987, the U.S. Army, EPA and the Minnesota Pollution Control Agency (MPCA) signed a three-party federal facility agreement (FFA). The Army, as the lead agency, is conducting the investigation and cleanup of the facility under the oversight of EPA and MPCA. In accordance with the FFA, the Army initiated many interim response activities under the Department of Defense (DoD) Installation Restoration Program. These efforts included a permanent granular activated carbon (GAC) water treatment system for the City of New Brighton, soil vapor extraction (SVE) systems at two areas (Sites D and G), shallow groundwater pump-and-treat systems at Site A and at Alliant Techsystems operational buildings I and K, a deep groundwater recovery system (the TCAAP Groundwater Recovery System, or TGRS), inspection, cleaning and testing of all sewer lines in the TCAAP sanitary sewer system, and thermal treatment of 1,400 cubic yards of PCB-contaminated soil. EPA and MPCA also installed a GAC water treatment system for the Village of St. Anthony.

To expedite cleanup of regional groundwater cleanup, the parties selected several additional remedies in 1992 and 1993. They included pumping of the containment plumes to prevent further migration (containment), treatment with GAC, discharge of treated water to the New Brighton municipal distribution system, provision of alternate water supplies to affected users of private wells, and drilling advisories and monitoring.

The parties selected the last part of the site’s remedy in December 1997. The remedies address contaminated soil and groundwater within the TCAAP boundary. They include excavation/stabilization and off-site disposal of contaminated shallow soils, characterization of on-site dumps to determine their contents, expansion of the shallow soil vapor extraction system to deep soils at Sites D and G, cleanup of shallow groundwater contamination at Sites A, I and K through the use of extraction wells/trenches and installation of sentinel wells, containment of the extensive deep groundwater plume and optimization of the extraction system, long-term monitoring and institutional controls, and annual reviews of emerging technologies that could accelerate timeframes for aquifer restoration.

Activities between 2006 and 2009 included the reconfiguration/optimization of the TGRS and several updates to site remedies. An extensive long-term monitoring program for groundwater, surface water and sediments is currently in place and will continue well into the future. Other recent and ongoing activities include groundwater treatment, investigation and cleanup of aquatic sites, cleanup planning for Round Lake, development of land use controls, and removal actions for the 535 Primer/Tracer Area and Building 102.

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Activity and Use Limitations

At this site, activity and use limitations that EPA calls institutional controls are in place. Institutional controls play an important role in site remedies because they reduce exposure to contamination by limiting land or resource use. They also guide human behavior. For instance, zoning restrictions prevent land uses – such as residential uses – that are not consistent with the level of cleanup.

For more background, see Institutional Controls.

VOCs (trichloroethene, tetrachloroethene, 1,2 dichloroethene)

heavy metals



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Enforcement Information

The U.S. Army is the responsible party for the New Brighton/Arden Hills Superfund Site. This site is being addressed through federal and state actions in accordance with the 1987 TCAAP Federal Facility Agreement.

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