Region 5 Superfund (SF)

U.S. EPA REGION 5
RAMSEY COUNTY
NEW BRIGHTON

Congressional District # 04

NEW BRIGHTON/ARDEN HILLS/TCAAP (USARMY)

EPA ID# MN7213820908
Last Updated: February, 2007

Site Description

The New Brighton/Arden Hills Superfund site consists of the Twin Cities Army Ammunition Plant (TCAAP) and all other areas of the surrounding communities historically contaminated by the migration of hazardous substances or contaminants from TCAAP. Between 1941 and 1981, waste material was disposed of at 14 disposal areas or sites within TCAAP. The total area of the Superfund site, including the offsite contaminated groundwater plumes, is approximately 25 square miles.

Site Responsibility

Responsibility for the site resides with the U.S. Army, Department of Defense.  This site is being addressed through federal and state actions in accordance with the 1987 TCAAP Federal Facility Agreement.

Threats and Contaminants

The wastes disposed of at TCAAP included volatile organic compounds (VOCs), semi-VOCs, metals, polychlorinated biphenyls (PCBs), cyanide, pesticides, and explosives. The primary impact to the surrounding communities has resulted from VOC contamination of the regional groundwater resource, which is used for municipal and private water supplies. 

Cleanup Progress

In 1987, the Army, U.S. EPA, and MPCA entered into a federal facility agreement (FFA) for the investigation and remediation of the site. In accordance with the FFA, the Army initiated numerous cleanup activities under the Department of Defense (DoD) Installation Restoration Program, including:

• A permanent granular activated carbon (GAC) water treatment system for the city of New Brighton, completed in June 1990.
• Soil vapor extraction (SVE) systems at two areas of the site (Sites D and G) in 1986, which have since removed over 218,000 lbs. of VOCs from soils.
• A shallow groundwater pump-and-treat system, installed at Site A in 1994 where VOC-contaminated groundwater in the shallow aquifer had migrated past the northwest boundary of TCAAP. Shallow groundwater pump-and-treat systems were also installed in 1988 at the Alliant Techsystems operational buildings I and K.
• A Boundary Groundwater Recovery System (BGRS) for which a ROD was signed in September 1987. Subsequent to the implementation of the BGRS, five source control wells were installed. The BGRS and source control wells together comprise the TCAAP Groundwater Recovery System (TGRS). To date the system has removed upward of 150,000 lbs. Of VOCs from the deep groundwater.
• Inspection, cleaning, and testing of all sewer lines in the TCAAP sanitary sewer system; work was completed by 1986.
• Thermal treatment of 1,400 cubic yards of PCB-contaminated soil pursuant to a ROD, signed in 1989.

Additional action was taken and included the construction of a GAC treatment system for the village of St. Anthony by U.S. EPA and MPCA. The system was completed in 1991, pursuant to a September 1986 Record of Decision.

In recognition of the need to expedite the remediation of regional groundwater contamination, U.S. EPA, MPCA, and the Army agreed to address the final remedy for the site in three stages or operable units. Operable Unit 1 (OU-1) addresses the North Plume of contaminated groundwater which has migrated off-TCAAP; Operable Unit 3 (OU-3) addresses the smaller, South Plume.

Records of decision, in which remedies for these operable units were selected, were signed in 1992 and 1993. The remedies, selected, include:

• pumping of the plumes to prevent further migration (containment);
• treatment with granular activated carbon;
• discharge of treated water to the New Brighton municipal distribution system;
• alternate water supplies to affected users of private wells; and
• drilling advisories and monitoring.

The OU-1 and OU-3 RODs provide for containment pump-and-treat systems comprised of wells which serve the dual purposes of containment and municipal water supply for the city of New Brighton. Construction and full operation of the OU-3 system began in 1994. Construction of the OU-1 system was completed in the second quarter, FY1999.

For the past several years, VOC levels in monitoring wells for the South Plume have been consistently non-detectable. In 2001, U.S. EPA and MPCA approved the Army's request to temporarily cease pumping of the OU-3 extraction well-and-treatment system for remediation purposes and maintain it in "standby mode" with continued groundwater monitoring.

The last component of the final remedy for the site, a ROD for Operable Unit 2 (OU2), was signed in December 1997. The remedies selected in this ROD address contaminated soil and groundwater within the TCAAP boundary. Major elements of these remedies include:

• excavation/stabilization and offsite disposal of contaminated shallow soils;
• characterization of onsite 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 have the potential to cost-effectively accelerate the time frame for aquifer restoration.

An extensive long-term monitoring program for groundwater, surface water, and sediments is currently in place and will continue well into the future.

By summer 1999, major components of the soils remediation component of the OU2 remedy had been designed and implemented. These components included:

• completion of a corrective action management unit (CAMU), providing a central area of the staging and stabilization of excavated soils;
• completion of the excavation/stabilization of 10,000 cubic yards of soil at Site A;
• characterization of the unpermitted landfill (UPL) at Site A;
• completion of the SVE pilot studies at Sites D and G;
• design of an SVE/air sparging system at Site A;
• characterization of unknowns at Sites B and 129-15;
• bounding of contaminated areas at Sites C, E, and H;
• completion of the Tier II ecological risk assessment workplan and preliminary field work;
• completion of the EE/CAs, action memos, and removal workplans for the Outdoor Firing Range and the Grenade Range; and
• initiation of the groundwater modeling effort for the optimization of the boundary groundwater containment system.

By summer 2002, the following on-TCAAP remedial and removal actions had been completed:

• excavation, stabilization, and offsite disposal of contaminated soils at Sites A, H, E, 129-3, and 129-5;
• placement of cover on Site 129-15;
• installation and operation of a soil vapor extraction system at Site A;
• closeout of Site B;
• removal of contaminated soil from the Grenade Range;
• removal of contaminated soil from the Outdoor Firing Range and the #150 Reservoir Site;
• preliminary assessment and site inspection of the 135 Primer/Tracer Area;
• preliminary assessments of the 535 Primer/Tracer Area;
• completion of soil vapor extraction at Sites D and G;
• field investigation of soils at Site D; and
• investigation of tar-like materials beneath the cover at Site G.
  

In 1996, the Army performed limited soil sampling at the 135 and 535 Primer Tracer Areas (PTAs). The PTAs were part of an Army mobilization mission at the time that the TCAAP preliminary assessment was performed and were, therefore, not investigated at the time. Additional work performed at these areas to evaluate their contamination status has included preliminary assessments in 2001 and site inspections (SI) in 2002 and 2003.  The second five-year review for the New Brighton/Arden Hills/TCAAP Site was completed in September 2004.

Ongoing activities being performed on-TCAAP include: 1) operation and maintenance of on-TCAAP groundwater remediation systems (Site A and TGRS), 2) annual performance monitoring of the groundwater remediation systems, and 3) annual private well inventory.

Currently (as of summer 2006) the following activities have been completed or are underway:

 1) reconfiguration/optimization of the TGRS;

2) Operable Unit 1 ROD Amendment - A ROD Amendment for OU-1 was signed in June 2006.  The purpose of this amendment is to improve the method by which success in the cleanup of the North Plume of off-TCAAP contamination is measures;

3) Operable Unit 2 ROD Amendment - The OU-2 ROD is in the process of being amended to address needed changes to the remedies for various portions of the OU-2 remedy(e.g., at Sites I, K, 129-15, and conditions at Site C);

4) Feasibility Study to address the findings of the Tier II Ecological Risk Assessment, especially as it relates to Round Lake, evaluating potential responses to the impact of TCAAP-related contaminants to onsite and adjacent aquatic ecosystems.

5) Operable Unit 3 ROD Amendment - A ROD Amendment for OU-3 was signed in August 2006.  The purpose of this amendment is to eliminate the requirement for the OU-3 extraction well, also known as the Plume Groundwater Recovery System (PGRS), as part of the OU-3 remedy because its purpose, to prevent the spread of the OU-3 plume at its leading edge, has been served.  The PGRS has been extracting clean water (i.e., non-detect for volatile organic carbon (VOC) contaminants) for at least five years.  The OU-3 plume has receded significantly toward the TCAAP, and it is expected to continue to recede.

Upon completion of the ROD Amendments and associated remedial work, as well as additional work related to the aquatic ecological risk assessment, and removal actions for the 135 Primer/Tracer Area and Building 102, construction completion for the site is expected in fiscal year 2009.

Success Story

The South Plume (Operable Unit 3 [OU3]) has receded to the point where the Plume Groundwater Recovery System (PGRS) extraction well is no longer needed for remediation purposes.  The well has been shut down and the shutdown made permanent through the recent Operable Unit 3  ROD Amendment.

Community Involvement

The communities surrounding TCAAP have been, and continue to be, very active in both the CERCLA cleaup and the property transfer issues at the Site.  A restoration advisory board (RAB) formed pursuant to Department of Defense guidance, composed of citizens from the local communities and charged with providing public input into the Army's cleanup of the Superfund Site, has been active since its inception in 1996.

The City of New Brighton has been an integral partner with the Army in the successful implementation and operation of the OU-1 and OU-3 groundwater extraction and cleanup remedies because it is the City's municipal wells which are serving, or have served, as the extraction wells for these remedies.

Finally, the Village of Arden Hills is closely involved in the proposed redevelopment of the 600+ acres of TCAAP property since that redeveloped property will be incorporated into the village.

Congressional Interest

The Minnesota Congressional delegation has taken an interest and played an active role in the Site largely as a result of the closure and anticipated redevelopment of TCAAP.  In the mid-1990's then Congressman Bruce Vento led a public dialogue which resulted in a redevelopment plan for TCAAP ("the Vento Plan").  The Vento Plan has provided the framework for subsequent redevelopment efforts. 

 

Property Reuse

Of the approximately 2400 acres of TCAAP, control over 1500 acres has been transferred to the U.S. Army Reserve and the Minnesota National Guard.  Smaller portions have been transferred to Ramsey County for a public works facility and a wildlife corridor, and the City of Arden Hills for a new City Hall.  Approximately 660 acres was authorized by the United States Congress to be excessed and is currently in the process of being transferred for redevelopment purposes.

Contacts

Remedial Project Manager, U.S. EPA
thomas barounis (barounis.thomas@epa.gov)
(312) 353-5577

Community Involvement Coordinator, U.S. EPA
stuart hill
(312) 886-0689

Aliases

NEW BRIGHTON / ARDEN HILLS
TWIN CITIES ARMY AMMUNITION PLANT
US ARMY TWIN CITIES AMMO PLT

 

Site Profile Information

This profile provides you with information on EPA's cleanup progress at this Superfund site.