Superfund Information Systems: Site Profile

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The 80-acre Reilly Tar & Chemical Corporation/St. Louis Park Plant site (Reilly site) is located near the intersection of Louisiana Avenue and U.S. Highway 7 in the city of St. Louis Park, in Hennepin County, Minnesota. A site map is found here. From 1917 to 1972, Republic Creosoting Company, owned by Reilly Industries, operated a coal tar distillation and wood treatment facility at the site. The facility discharged thousands of gallons per week of wastewater in several ditches that flowed to an adjacent peat bog. The wastes generated at the site were mostly polycyclic aromatic hydrocarbons, which contaminated soil at the site, the peat bog, and groundwater beneath the site. Six drinking water wells in St. Louis Park, and one in the city of Hopkins, were closed due to contamination.

In 1972, the site was sold to the City of St. Louis Park. From 1978 to 1981, seven municipal wells were closed due to contamination. In 1984, EPA issued a remedy decision for construction of a drinking water treatment plant for two St. Louis Park wells, and the plant was constructed in 1985. In 1986, EPA selected a remedy for most of the remainder of the site. The bog was filled and covered with clean fill in 1986. The city began pumping two wells to control more highly-contaminated groundwater near the source in 1987. In subsequent years, the city began pumping additional wells further from the source to control the spread of the plume. A treatment plant for St. Louis Park drinking water well SLP4 was added in 1992. It is estimated that approximately 47,000 people use the groundwater from aquifers near the site, which are now treated to meet all required health standards.

In 2002 the city redeveloped the site into Louisiana Oaks Park. Portions of the northern end of the site have been developed as a residential complex.

The remedy left contaminated soil in place at the site, covered by clean soil. Periodically, the city conducts work at the site that requires digging. Plans for the work, including safe handling of any contaminated soils that are found, and air monitoring to protect workers and nearby residents, are approved by EPA and the Minnesota Pollution Control Agency.


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What Is Being Done to Clean Up the Site?

This site is being addressed through federal, state, municipal, and PRP actions.

FYRs are prepared to evaluate the implementation and performance of site remedies to determine if they remain protective of human health and the environment. FYRs are repeated every five years.

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What Is the Current Site Status?

EPA recently completed a new Community Involvement Plan and its fifth Five-Year Review report for the site.

The Minnesota Department of Health recently released Cancer Occurrence in St. Louis Park, 1993-2012.

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EPA’s Involvement at the Site

In 1980, Congress enacted the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), also known as Superfund. CERCLA’s major emphasis is on the cleanup of inactive hazardous waste sites and the liability for cleanup costs.

In 1982, EPA provided funds to the Minnesota Pollution Control Agency (MPCA) to clean out two contaminated wells at the Reilly Tar & Chemical Corporation/St. Louis Park Plant site (Reilly site) which had been used for disposal of site wastes.

The Reilly site was listed on the National Priorities List (NPL) in 1984. The NPL is a roster of the nation's hazardous waste sites eligible for investigation and cleanup under the Superfund program.

In 1984, the first Record of Decision (ROD) was signed requiring Reilly Tar, the potentially responsible party (PRP), to perform the below activities.

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.

Subsequent RODs were signed in 19861990, 1992, and 1995, and also required the PRP to perform specific activities .

A timeline of site events from to 1917 to 2014 prepared by EPA is here, and a timeline from 1969 to 1985 prepared by the MPCA is here.

In September 1986, a Consent Decree (CD) was signed by the PRP, EPA, and MPCA. The CD contains a Remedial Action Plan designed to protect public health and welfare and the environment from known or threatened pollutant releases on or from the Reilly site. Under the CD, Reilly must undertake remedial investigations, feasibility studies, remedial designs, and remedial actions. Following negotiation of the CD, cleanup has been overseen by EPA, in coordination with MPCA and the Minnesota Department of Health (MDH).

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. The bog was filled and covered with clean fill in 1986. The city began pumping two wells to control more highly-contaminated groundwater near the source in 1987. 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.

Under the terms of the CD, the City of St. Louis Park monitors groundwater contamination and operates pumping wells at the site. Five wells located nearer to the site pump more highly-contaminated groundwater to remove contaminants and to keep them from spreading out further. After treatment to meet the requirements of a permit, the City discharges the water from three of the wells to a pond that drains into Minnehaha Creek. Water from the other two wells is discharged to the sanitary sewer.

St. Louis Park operates two additional pumping wells located in areas that are more lightly contaminated. Pumping at these two wells serves two purposes – to help keep the contamination from spreading further, and to supply water that is used by the city. Each of these wells has its own treatment facility where the water is treated for polycyclic aromatic hydrocarbons (PAHs), and for iron and other naturally occurring minerals, before going into the City drinking water system. (Other drinking water wells operated by the City are not contaminated with PAHs, but are treated for iron and other naturally occurring minerals.)

A chronological list of site cleanup activities from 1984 to 1995 is here

Section 121 of CERCLA, as amended by the Superfund Amendments and Reauthorization Act, requires that remedial actions which result in any hazardous substances, pollutants, or contaminants remaining at a site be subject to a five-year review (FYR). FYRs are prepared to evaluate the implementation and performance of site remedies to determine if they remain protective of human health and the environment. FYRs are repeated every succeeding five years. Five FYRs have been prepared for the Reilly site, in 199620012006, 2011, and 2016. Each FYR makes conclusions regarding whether the site remedy is protective of human health and the environment, and includes recommendations to assure long-term protectiveness.

MPCA and EPA completed the fourth FYR for the Reilly site in 2011. That review concluded that the actions being taken meet the objectives of the remedy decision, but that protectiveness could not be determined until a vapor intrusion investigation was complete. EPA, MPCA, and the City of St. Louis Park held open houses on March 3, 2011 to answer questions about upcoming vapor intrusion testing near the Reilly site.

Testing was conducted in June 2011 to find out if vapors from underlying contaminated groundwater or soil in the area of the Reilly site are causing indoor air contamination in area homes and structures. EPA collected sub-slab (the space under the basement floor) soil gas samples. Some information on the 2011 sampling activity is found in these fact sheets. Owners and residents of buildings that underwent sub-slab sampling received results and information about EPA's next steps to detect whether or not there is a concern for vapor intrusion.

EPA performed a second round of sampling in January 2012. Both sub-slab soil gas and indoor air samples were collected at 25 locations on six properties on and near the site. Additional information on vapor intrusion is found in this fact sheet. There appeared to be no immediate danger to human health, but it was unclear what role vapor intrusion may have been playing in the indoor air quality in the tested properties.

A third sampling effort was conducted at the Reilly site in two mobilizations spanning November 2012 to January 2013. Where contaminants were detected in indoor air, they were below or within EPA’s acceptable ranges.

Since the third round of sampling results could not be used to make risk management decisions at the Reilly site, a fourth and final sampling event occurred at the Reilly site in June 2013. EPA concluded that there was no danger to human health or threats from the vapor intrusion exposure pathway.

A summary of the results of the vapor intrusion pathway investigation is found here.

EPA completed their investigation and updated the FYR in 2014. The addendum to the FYR documented that there was no unacceptable risk from the vapor pathway at the site.

In 2011, the city of St. Louis Park worked on a pedestrian bridge around the Reilly site and questions arose from citizens about the city’s work. To answer those questions and to provide a summary of the site history and cleanup, EPA held an open house on November 12, 2015. Open house information can be found on this fact sheet.

EPA representatives were in the Reilly site area from February 2 - 4, 2016 to interview residents about the site. The MPCA and MDH joined EPA in this effort. Additional information can be found in this postcard.

EPA recently completed a new Community Involvement Plan for the site.

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Sampling and Monitoring

The City of St. Louis Park monitors groundwater contamination and operates a number of pumping wells at the site.

St. Louis Park regularly samples water quality in municipal drinking water wells, and also samples a wide network of 75 groundwater monitoring wells in 5 aquifers.

EPA, the Minnesota Pollution Control Agency (MPCA), and MDH oversee the City’s groundwater monitoring and ensure that the treatment remains effective.

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Enforcement Information

The Consent Decree (CD) filed on September 5, 1986 is found here. MPCA, MDH, Reilly Industries, and several other parties entered into a CD to clean up the site. The City of St. Louis Park agreed to share responsibility for implementing the remedy, with initial funding by Reilly.

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