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Congressional District # 05


EPA ID# MN3170022914
Last Updated: December, 2012

Site Description

The 83-acre Naval Industrial Reserve Ordnance Plant (NIROP) site is located about 700 feet from the Mississippi River in Fridley, Minnesota. The U.S. Navy and its contractors have produced advanced weapons systems at the facility since 1940. In 1981, trichloroethylene (TCE) was discovered in on-site groundwater wells and in the City of Minneapolis's drinking water treatment plant intake pipe, which is located in the Mississippi River about 1,500 feet downstream from the site. In 1983, investigations identified pits and trenches in the "North 40" area of the NIROP site where drummed wastes had been disposed of. Contaminated soil and drums have since been excavated from the "North 40" area and properly disposed of off site.

In August 1988, a remedial investigation and feasibility study (RI/FS) was completed. The study indicated that groundwater originating from the site, contaminated primarily with TCE, was flowing into the Mississippi River at TCE concentrations of up to 37,000 parts per billion (ppb). In contrast, the Safe Drinking Water Act set the maximum contaminant limit (MCL) for TCE in public drinking water supplies at 5 ppb. Concentrations of TCE in area monitoring wells adjacent to the river have since decreased to levels ranging from non-detect to 150 ppb. 

Over 200,000 people live within three miles of the NIROP site. An estimated 29,000 people obtain drinking water from public wells located within three miles of the site; however, the majority of the population in the city of Minneapolis, estimated to be 500,000 residents, uses the Mississippi River as its primary drinking water source.

The U.S. Environmental Protection Agency (EPA) proposed the NIROP site to the National Priorities List (NPL) in July 1989 and finalized the site on the NPL in November 1989.

Site Responsibility

The U.S. Navy is conducting the cleanup and groundwater monitoring action at the NIROP site under the oversight of EPA and the Minnesota Pollution Control Agency (MPCA).

Threats and Contaminants

Groundwater at the NIROP site is contaminated predominantly with the solvent TCE. Methylene chloride and polycyclic aromatic hydrocarbons (PAHs) were detected in subsurface soil. Potential health risks exist for individuals who ingest or come into direct contact with contaminated groundwater or soil. Because the site is fenced and no private wells are located nearby, no residents are currently being exposed to the contaminants. VOCs above MCLs have not been detected in the drinking water from the Cty of Minneapolis water intake pipe in the Mississippi River since the 1980s.

Cleanup Progress

EPA divided the NIROP site into three portions, termed "operable units," for ease of addressing its contaminant issues. Operable Unit 1 (OU1) applies to the groundwater at the site. OU2 and OU3 apply to contaminated soil beyond the 57-acre NIROP site building (OU2) and to the contaminated soil beneath the site building (OU3).

On September 28, 1990, EPA issued a Record of Decision (ROD) for OU1 that selected the cleanup remedy for the contaminated groundwater. The selected remedy was to hydraulically contain the groundwater contaminant plume using an extraction well system. In September 1992, a groundwater extraction well system began operating at the site. In 1995, the extraction system was modified so that the hydraulic containment requirement in the ROD could be achieved. Initially, extracted groundwater was treated at a local wastewater treatment plant and, between 1993 and 1997, more than 960 million gallons of contaminated groundwater were sent to the local treatment plant. An on-site treatment system was completed in November 1998, and treated groundwater is now being discharged to the Mississippi River. 

Additional modifications to the groundwater extraction system were completed in fall 2001, including the installation of four new extraction wells and the abandonment of three old extraction wells. In 2011, one of the primary extraction wells was replaced with three new wells. An overall review of the extraction system is being conducted in 2012 to determine if additional extraction wells need to be replaced or if new ones need to be installed to supplement the existing system. More than 4.3 billion gallons of groundwater have been treated since 1991, resulting in the recovery of more than 38,000 pounds of TCE, accounting for a considerable reduction in the VOC concentrations at the NIROP site.

EPA issued a ROD for OU2 and OU3 in September 2003 in which certain engineering and institutional controls were selected as the remedy. For OU2, two institutional controls (ICs) were to be implemented. The first IC for OU2 prohibits the disturbance of soil deeper than 3 feet below ground surface without prior written approval of EPA and MPCA, and the second IC for OU2 restricts the property to industrial and limited commercial use until and unless EPA and MPCA determine that concentrations of hazardous substances in the soil have been reduced to levels which allow for less restrictive uses. The ICs implemented for OU3 prohibit both the disturbance of soil below the building's former plating shop area and the removal of the concrete floor above the plating shop without written approval of EPA and MPCA.

Because contamination remains on site, reviews of the cleanup remedy are required every five years. The third five-year review was completed in 2008. The review found that the remedy at the site is protective of human health and the environment in the short term. Several issues raised in the 2008 five-year review concerning the improvement of the long-term effectiveness of the groundwater remedy are being addressed by the U.S. Navy under EPA and MPCA oversight. The next five-year review will be completed by October 2013.

Community Involvement

Prior to issuance of the Record of Decision, multiple public meetings were held in Fridley to present investigation results and proposed cleanup plans and gather comments and input from the local community. The cleanup team for NIROP (MPCA, EPA, and the Navy) participated in the meetings. The NIROP Technical Review Committee (established in 1989) was modified to become a Restoration Advisory Board (RAB) in 1995 to improve public participation by providing greater direct community involvement. RAB community members provided input on technical documents and restoration activities. After the remedy was implemented and contaminant levels were significantly reduced, public interest waned and the RAB was dissolved in 2006.

Property Reuse

The property is being used as a manufacturing facility.


Remedial Project Manager, U.S. EPA
sheila desai (desai.sheila@epa.gov)
(312) 353-4150

Community Involvement Coordinator, U.S. EPA
teresa jones
(312) 886-0725




Site Profile Information

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


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