Superfund Information Systems: Site Profile

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Cleanup Activities

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The 22,357-acre Milan Army Ammunition Plant (MLAAP) opened in 1942 for wartime munitions production. That work has recently moved to standby, but could restart if needed. Today, MLAAP has two primary military missions: 1) storage of munitions; and 2) support for U.S. Army (Army) National Guard and Reserve units for staging equipment and training. Following many years of munitions production and due to the discovery of munitions-related contamination in soil and groundwater, the U.S. Environmental Protection Agency placed the site on the Superfund program’s National Priorities List (NPL) in 1987.

Working together, the EPA, the Tennessee Department of Environment and Conservation (TDEC), and the Army have investigated MLAAP soils and groundwater and have taken action to protect workers, local residents and the environment. Currently, site contamination does not threaten people living and working at or near the site. By extracting and treating contaminated groundwater, capping and containing contaminated soil, conducting groundwater monitoring, and performing required Superfund regulatory Five-Year Reviews, EPA, TDEC and the Army continue to protect people and the environment from site contamination.

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What Has Been Done to Clean Up the Site?

The 22,357-acre site is an active military installation southeast of the City of Milan in western Tennessee. The installation includes many buildings and storage facilities. Rural residential and agricultural land borders the site to the north, south and east. Residential areas and the City of Milan border the site to the west and northwest.

The installation began operating in 1942, producing and storing fuses, boosters and ammunition. Over the many years of operation, land disposal of waste products and  hazardous materials along with uncontrolled wastewater disposal practices resulted in the contamination of soil and groundwater across portions of the Post. In 1987, EPA listed the site on the Superfund NPL. Coordination through a three-party "Federal Facility Agreement" between the Army, the EPA, and TDEC has provided a balanced approach to contaminant investigation, characterization, and clean-up activities across the entire site.

The Army leads site investigation and cleanup activities, with oversight, technical, and regulatory support provided by EPA and TDEC.
  • In the early 1990s, the Army worked with the City of Milan to relocate municipal water supply wells affected by contaminated groundwater. The Army completed construction of the pump-and-treat system for OU-1 in 1995. The system began operating at full capacity in 1998. The Army completed construction of a second pump-and-treat system in 1999 to address contamination at OU-3 and a third for OU-4 in 2002. The final Sitewide Groundwater Record of Decision was signed on July 31, 2014, with the goal being complete groundwater aquifer restoration by the end of 2074.
  • In 1995, the Army completed an extension of an existing cap to address subsurface contamination at OU-2. The Army also removed soil from OU-3/4 areas and successfully capped a number of small areas with soil contamination. Monitoring of these capped areas is on-going.
  • In 2011, the Army constructed several caps across the OU-5 Open Burning Ground area to address contaminated soils. Also at OU-5, in 2013, the environmental risk associated with surficial munitions debris was evaluated and addressed. Existing land use controls including fencing, restricted access, and periodic site inspection will continue to protect human health and the environment at this OU.
  • In 2015, EPA completed the site’s fourth Five-Year Review [this process evaluates the protectiveness of past clean-up decisions and the current site status as it relates to risk to human health and the environment]. It found that final clean-up decisions for soils across the Post remain protective of human health and the environment. The on-going groundwater extraction activities and existing land use controls prevent unacceptable exposure to contaminated groundwater. The completion of the groundwater extraction and treatment action in 2074, should restore the aquifer and it will no longer contain munitions contaminants above drinking water standards. At that point it will be fully protective of human health and the environment.
  • The next Five-Year Review is due in 2020.

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What Is the Current Site Status?

Cleanup activities have focused on contaminated soils and groundwater. Investigation and characterization activities have divided the site into five areas, some with overlapping  contamination. These areas are referred to as operable units, or OUs. Several of the OUs (i.e., OU-1, OU-3, OU-4, and OU-5) are combined into a Sitewide Groundwater OU since they all contain contaminated groundwater. The remediation of the Sitewide Groundwater OU will (in 2074) result in aquifer restoration; OU-2 addressed the O-Line Ponds contaminated soil; OU-3 and OU-4 addressed the Northern Industrial Area contaminated soils; OU-5 had two cleanup decisions; Open Burning Grounds Soils cap and restrict access by land use controls and the Open Burning Ground Munitions Response site which is also controlled by existing land use controls across OU-5.

Currently, all of these OUs are either capped, closed, or are undergoing cleanup activities (i.e., groundwater extraction and treatment). Annual inspection reports, system operations reports and status reports will keep EPA, the Army and TDEC informed of ongoing activities. No other investigative or remedial activities are necessary.

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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.

Land Use Controls (LUCs) are legal measures that limit human exposure by restricting activity, use, and access to properties with residual contamination. The Army has LUCs in place on MLAAP and on certain adjacent private properties to prevent access, use, and exposure to contaminated groundwater as part of the site-wide groundwater remedy. LUCs also include periodic inspections and reporting requirements. In addition, the City of Milan has city ordinances in place (city codes 18-122 and 18-309) to protect residences.

City Ordinance 18-122 details restrictions on the supply and resale of water. This ordinance restricts water supply within the city to water supplied by the City of Milan only, which also cannot be re-sold, or otherwise disposed of without written permission from the city. The ordinance does not include water for groundwater heat pump systems or other similar installations.

City Ordinance 18-309 details a restriction on water from a source other than public supply. Any water from a source other than the public supply which could be used for potable (drinkable) or domestic purposes, and which is not supplied by the city’s potable system, must be labeled in a visible/noticeable way as WATER UNSAFE FOR DRINKING, with black letters at least one-inch high on a red background.

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