Congressional District # 04
NEW BRIGHTON/ARDEN HILLS/TCAAP (USARMY)EPA ID# MN7213820908
Last Updated: August, 2013
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, wastes were disposed at 14 areas, or sites, within TCAAP. The total area of the Superfund site, including the offsite contaminated groundwater plumes, is approximately 25 square miles.
Site ResponsibilityThe 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.
Threats and Contaminants
The wastes disposed 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.
Within the TCAAP boundaries, soils were contaminated with solvents, semivolatiles, metals and PCBs. In addition, a number of areas (Sites D, G, H and 129-15) were used as dumps. Additionally, a number of areas (Grenade Range, Outdoor Firing Range), were impacted by lead from the testing of ammunition and grenades. Finally, the transmission of industrial wastes via the storm sewer system into Round Lake, a 120 acre lake adjacent to TCAAP, a unit of the Minnesota Valley National Wildlife Refuge, resulted in the contamination of lake sediments with heavy metals and PCBs.
Cleanup ProgressIn 1987, the Army, U.S. Environmental Protection Agency (U.S. EPA), and Minnesota Pollution Control Agency (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 Record of Decision (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 pounds 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 Record of Decision signed in 1989.
Additional action was taken and included the construction of a granular activated carbon (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 ROD.
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 (OU1) addresses the North Plume of contaminated groundwater which has migrated off-TCAAP; Operable Unit 3 (OU-3) addresses the smaller, South Plume.
RODs, 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 GAC;
- 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 OU1 and OU3 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 OU3 system began in 1994. Construction of the OU1 system was completed in the second quarter, FY1999.
For a number of years, VOC levels in monitoring wells for the South Plume were consistently non-detect. In 2001, U.S. EPA and MPCA approved the Army's request to temporarily cease pumping of the OU3 extraction well-and-treatment system for remediation purposes and maintain it in "standby mode" with continued groundwater monitoring. After a minimum of five years of non-detect VOC concentrations, the Army requested that the OU3 ROD requirement for operating the South Plume extraction well be terminated. After reviewing all relevant groundwater monitoring data, U.S. EPA and MPCA concurred with the Army's request and in June 2006 signed the OU3 ROD Amendment. The OU3 ROD Amendment removes groundwater extraction and associated remedy components and retains the alternate water supply, groundwater monitoring and institutional control components of the original remedy.
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.
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.
The remaining cleanup action required by the OU2 ROD, excavation and installation of soil covers at Site C, was completed in May 2009. An extensive long-term monitoring program for groundwater, surface water, and sediments is currently in place and will continue well into the future.
Between 2006 and 2009 the following activities were completed:
(1) reconfiguration/optimization of the TGRS;
(2) Operable Unit 1 ROD Amendment - A ROD Amendment for OU1 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 measured;
(3) Operable Unit 2 ROD Amendments - The OU2 ROD was amended to address needed changes to the remedies for various portions of the OU2 remedy(e.g., at Sites I, K, 129-15, and conditions at Site C). The amendment process included: OU2 ROD Amendment 1, addressing changes in the soils remedy at Site C-2, was signed in July 2007. Amendments Nos. 2 (Site I Groundwater) and 3 (OU2 Soils and Dumps) were signed in spring 2009, as were Explanations of Significant Difference (ESDs) for Groundwater (ESD 1) and Soil (ESD 2): remedy changes which are not significant enough to warrant amending the ROD;
(4) Operable Unit 3 ROD Amendment - A ROD Amendment for OU3 was signed in August 2006. The purpose of this amendment is to eliminate the requirement for the OU3 extraction well, also known as the Plume Groundwater Recovery System (PGRS), as part of the OU3 remedy because its purpose, to prevent the spread of the OU3 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 OU3 plume has receded significantly toward TCAAP, and it is expected to continue to recede.
(5) Building 102 Groundwater Plume - During performance of an Environmental Site Assessment (ESA) by the developer of the property transfer parcel of TCAAP, the developer's contractor discovered VOC contamination around Building 102. Subsequent investigation by the Army of the Building 102 area, documented in the Groundwater Investigation Report for Building 102 (January 2006) delineated a plume of shallow VOC-contaminated groundwater originating underneath the building. An EE/CA for the site was completed in July 2008. The EE/CA recommended monitored natural attenuation as a non-time-critical removal action for the contaminated groundwater. The removal action was implemented and completed in 2009.
(6) Long-Term Operation and Maintenance Activities - These activities will continue to be monitored through the Annual Performance Report, which the Army will continue to generate for regulatory review until the cleanup at the Site is complete.
Ongoing activities include:
(1) Operation and maintenance of on-TCAAP groundwater remediation systems (Site A and TGRS); annual performance monitoring of the groundwater remediation systems; and annual private well inventory.
(2) Aquatic Sites Feasibility Study (FS) - A FS to address the findings of the 2005 Tier II Ecological Risk Assessment has gone through several interations. U.S. EPA, MPCA and the U.S. Army have agreed to complete the FS for Rice Creek, Marsden Lake, Sunfish Lake and Pond G (all located on TCAAP) and to collect additional sediment data so as to better identify the best sediment remedy for Round Lake, for which a remedial decision will be made separately.
Amendment #4 to the OU2 ROD was completed in January 2012. The amendment documents the selection of remedies for the aquatic sites that remain on the TCAAP property. It also documents final remedies for sites where previous removal actions addressed the outstanding contamination issues with a No Further Action (NFA) decision. These include Site K and Building 102.
As of October 2011, additional sediment investigation has been completed in Round Lake. The results of the investigation will support the development of a final feasibility study for Round Lake, to be completed in FY2013.
In 2010 U.S. EPA and MPCA approved the Army's Land Use Control Remedial Design (LUCRD) document. The LUCRD defines the LUCs required on the TCAAP property and the roles and responsibilities, primarily of the Army, in implementing, maintaining, monitoring and enforcing the LUCs.
Based upon the additional work related to the Aquatic FS, and removal actions for the 535 Primer/Tracer Area and Building 102, construction completion for the site is expected in fiscal year 2014.
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.
The New Brighton Contaminated Groundwater Remediation System (NBCGRS), the remedy for the large North Plume of contaminated groundwater (Operable Unit 1), continues to operate as an effective gradient control system. Groundwater monitoring indicates that, generally, the contaminant plume continues to decrease in both concentration and size.
With the completion of the on-site (on-TCAAP) cleanup and emplacement of remedies, cleanup of the New Brighton/Arden Hills/TCAAP Superfund Site is almost completed. Final completion will occur when a remedy for Round Lake has been selected and implemented.
The communities surrounding TCAAP have been, and continue to be, active in both the CERCLA cleanup 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 OU1 and OU3 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.
The Minnesota Congressional delegation continues to follow the progress of cleanup and property transfer at the Site. 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.
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.
In April 2013 the Army transferred 387 acres of the former TCAAP to Ramsey County, which intends to redevelop it for multiple uses. A groundbreaking ceremony to kick off the redevelopment process was held on June 7, 2013.
ContactsRemedial Project Manager, U.S. EPA
thomas barounis (email@example.com)
Community Involvement Coordinator, U.S. EPA
AliasesNEW BRIGHTON / ARDEN HILLS
TWIN CITIES ARMY AMMUNITION PLANT
US ARMY TWIN CITIES AMMO PLT