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Congressional District # 05


EPA ID# MND980609804
Last Updated: March, 2012

Site Description

The 80-acre Reilly Tar & Chemical Corporation/St. Louis Park Plant site, in Hennepin County, Minnesota, was used for coal tar distillation and wood preserving from 1917 to 1972. The site was sold and converted into recreational and residential areas in 1972. Wastes from site operations were disposed of on the site and in a network of ditches that discharged to an adjacent wetland. The wastes generated at the site were predominantly polynuclear aromatic hydrocarbons (PAHs). Soil and groundwater beneath the site are contaminated. Approximately 43,000 people use the groundwater from the aquifers, contaminated by the site. Portions of the northern end of the site have been developed as a residential complex. From 1978 to 1981, seven municipal wells were closed due to contamination. 

Site Responsibility

This site is being addressed through federal, state, municipal, and potentially responsible parties' actions. 

Threats and Contaminants

The wastes generated at the site were predominantly PAHs. Soil and groundwater beneath the site are contaminated. 

Cleanup Progress

In 1982, the United States Environmental Protection Agency (U.S. EPA) provided funds to the Minnesota Pollution Control Agency (MPCA) to clean out two contaminated wells which had been used for disposal of site wastes. In 1984, a consent order was issued, requiring Reilly Tar, the potentially responsible party (PRP) as owner and operator of the site, to

1) construct a granular-activated carbon treatment plant for two existing contaminated municipal wells,

2) restore drinking water, and

3) contain the contaminant plume from contaminating other municipal wells.

The granular activated carbon treatment plant was completed in 1986. A consent decree (CD) was subsequently signed by the PRPs, U.S. EPA, and MPCA in September 1986. In 1986 and 1987, a number of pumping wells were constructed in the various groundwater aquifers beneath the site to remove the contaminant sources and to contain the spread of the contaminant plume. Another granular activated carbon treatment plant was completed in 1993 to allow a municipal well to be used for containment of the contaminant plume. Two additional pumping wells were also completed in 1991 and 1995.  

An additional pumping well was constructed in summer 1997. Construction at the site is now complete, and a preliminary close-out report was issued on June 30, 1997. 

The second five-year review was conducted in September 2001 to assure continued protectiveness of the remedial actions of the site.  The five-year review concluded that the site remedy was currently protective of human health and the environment.  The five-year review recommended that additional groundwater monitoring and groundwater modeling be performed to assure long-term protectiveness of the groundwater pumping wells in containing the contaminant plume.  

The third five year review for the site was completed on September 28, 2006.  This five-year review evaluated the protectiveness of the remedy at the site and required the following actions:

1.) Further evaluation will be performed of the need for additional pumping of wells in the Prairie
du Chien Aquifer to achieve gradient control. The evaluation will also assess the need for
additional monitoring wells.
2.) Further evaluation of the effect of pumping St. Peter Aquifer municipal well SLP-3 on
contaminant migration in the upper Platteville Aquifer will be performed.
3.) Further evaluation will be performed of the condition of multi-aquifer Monitoring Well W70
which may be contributing to contamination of the Prairie du Chien Aquifer. The well may be
sealed if groundwater modeling shows significant contaminant impact from the overlying St. Peter
4.) Monitoring will be performed to determine whether the extent of vertical migration of
contamination between aquifers, predicted by groundwater modeling, can be verified.
5.) An evaluation will be performed of the potential for vapor intrusion into on-site buildings and
soil gas monitoring/indoor air sampling will also be performed, if necessary.
6.) Implement and maintain long-term, effective institutional controls.

Monitoring well W70 has been sealed.  An evaluation of the potential for vapor intrusion was conducted in 2008 and follow-up soil gas monitoring in planned for early 2011.  EPA plans to contact property owners in 2011 regarding institutional controls, where needed, to restrict the use of properties at the site.  The evaluation of contaminated groundwater issues including  pumping effects, gradient control, and vertical migration are being discussed by EPA, MPCA, and the city of St. Louis Park.

MPCA and EPA completed the fourth Five Year Review for the site in June 2011.  The determination on the protectiveness of the remedy was deferred until results from the vapor intrusion investigation are reviewed.  EPA, in consultation with State and local agencies, is conducting the vapor intrusion investigation.  Sampling was completed in June 2011 and January 2012. 

Success Story

The site is being reused for commercial, residential, and recreational purposes.

Property Reuse

Several townhomes and apartment buildings were constructed on-site in the 1970's.   More recently, a major park improvement project was completed in 2002, a commercial building was constructed in 2004 and a road improvement project was completed in 2004.  A construction plan for each project was reviewed by the Agencies to assure that activities were conducted in a safe and environmentally appropriate manner.            


Remedial Project Manager, U.S. EPA
leah evison (evison.leah@epa.gov)
(312) 886-2064

Community Involvement Coordinator, U.S. EPA
Heriberto Leon
(312) 886-6163




Site Profile Information

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


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