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Congressional District # 08


EPA ID# MND039045430
Last Updated: December, 2012

Site Description

The St. Louis River site is made up of two state Superfund sites - the St. Louis River/Interlake/Duluth Tar site (SLRIDT) and the U.S. Steel site.  In 1983, the United States Environmental Protecton Agency (EPA) added the combined site to EPA's National Priorities List (NPL).  Both sites are located on the south side of Duluth, Minnesota, along the St. Louis River, which flows into Lake Superior.  The SLRIDT site is four miles upstream of the lake and the U.S. Steel site is eight miles upstream of the lake.  Drinking water for the city of Duluth is supplied from an intake several miles into Lake Superior.

St. Louis River/Interlake/Duluth Tar Site

The SLRIDT site is located in the West Duluth neighborhood of Duluth.  The site had been used for industrial purposes since at least the 1890's.  Pig iron and coking plants and a water/gas plant began operation at the site in 1904.  Tar and chemical companies used byproducts of the iron companies' coking operations to make other products, including tar paper and shingles.  The tar and chemical companies closed operations in 1948.  The iron plant closed its operations in 1961 and toppled the blast furnace and emptied the coke ovens in 1962.

The site encompasses about 255 acres of land and river embayments, wetlands, and shipping slips.  The land portion includes the 59th Avenue Peninsula (Hallett Peninsula) and the 54th Avenue Peninsula and is bounded on the north by a Burlington Northern railroad right-of-way.  The aquatic portion includes Stryker Bay, Slip 6, Keene Creek Bay/Slip 7, and a portion of the St. Louis River to the south of the two peninsulas and slips.  A small part of the Sediment Unit is in waters of the State of Wisconsin.  Stryker Bay is a shallow water embayment with emergent wetlands at the north end.  Boat Slip 6 is a deep-water environment, used for loading and unloading ships.  Keene Creek Bay/Boat Slip 7 is emergent wetlands and a shallow water environment, grading into a deep-water environment.

The upland portion of the site is zoned for industrial use.  Approximately 960 people live within one half mile fo the site.  Residences are located to the west on the 63rd Avenue Peninsula and to the north of the railroad tracks.  A walking trail and boat docks are along the western bank of the Stryker Embayment.  A campground, school, community center, and a school play field are located within one mile of the site's boundaries.

U.S. Steel Site 

The U.S. Steel site is located in the southern portion of the city of Duluth, south of the Morgan Park neighborhood.  The site was an integrated steel mill (USX Duluth Works) consisting of coke production, iron and steel making, casting, primary rolling and roughing, hot and cold finishing, and galvanizing.  The steel mill and coke production facility operated from 1915 until 1979 and made steel products such as nails, wire, and steel sign posts.  In 1979, the blast furnaces, open hearth furnaces, fuel oil storage tanks, and a portion of the rolling mill were demolished.  By 1988, the material storage area and most of the remaining building were demolished.

The site is bounded by the residential and light-industrial neighborhood of Morgan Park to the north, the St. Louis River (also called Spirit Lake in this area) to the east, and Duluth Missable and Iron Range Railroad property to the west and south.  The site covers aproximately 500 acres of land and 200 acres of sediment.  Parts of the site are steep and hilly.  A stream drains the northern part of the site near the former coke plant and empties into the St. Louis River.  During operations at the site, much of the waste from the coke plant and the "hot side" of the steel plant were discharged to a settling basin formed by a control structure in the stream.  Wastes from the "cold side" of the steel plant were discharged directly to the river through a small basin known as the Wire Mill Settling Basin located adjacent to the river.

Site Responsibility

This consolidated site is part of EPA's Deferral Pilot Project and was placed under state of Minnesota jurisdiction in 1995.  The Minnesota Pollution Control Agency (MPCA) is the lead agency for overseeing cleanup of both SLRIDT and USS sites by state and potentially responsible party (PRP) actions. 

Threats and Contaminants

Past industrial operations and disposal activities at the SLRIDT site resulted in tar, polycyclic aromatic hydrocarbons (PAHs), volatile organic hydrocarbons (VOCs), cyanide, naphthalene, and heavy metal (including mercury) contamination of soil, groundwater, and sediment.  Past industrial operations and disposal activities at the U.S. Steel site have contaminated soil, groundwater, surface water, and sediments with PAHs, semi-volatile organic compounds (SVOCs), and heavy metals.  Other contaminants such as PCB and dioxins/furans have also been found on land and in the sediment. 

The St. Louis River was impacted by both of the SLRIDT and U.S. Steel sites.  In this area the river is an estuary with adjacent industrial and residential uses but also is a large natural river/estuarine system with abundant wildlife and productive fisheries. The state of Minnesota has issued a fish consumption advisory for area fish for mercury.  As directed by MPCA, the site potentially responsible parties (PRPs) have posted “no sediment contact” warning signs at the U.S. Steel site, discouraging direct sediment contact in the area.

Cleanup Progress

St. Louis River/Interlake/Duluth Tar Site

The SLRIDT site was cleaned up as three separate Operable Units (OUs) or stages named "Tar Seeps," "Soil," and "Sediment."  In 1990, EPA and MPCA issued a Record of Decision (ROD) for the Tar Seeps OU. The remedy included excavation of the tar seep wastes and transportation of the wastes to be burned offsite for energy recovery at a facility in Hannibal, Missouri.  In response to an MPCA request, the work was conduced by the PRPs and was completed in 1994.  In 1995, MPCA issued a cleanup decision for the Soil OU which included excavation, thermal desorption, and landfilling.  The PRPs conducted this cleanup and completed it in 1997.  Because the current and future land use of the upland portion of the site is industrial, remedial actions included cleaning up the site to accommodate a future industrial uses.

In 2004, MPCA issued a ROD for the Sediment OU.  The remedy included dredging of contaminated sediment; construction of a Confined Aquatic Disposal (CAD) facility; capping and surcharging over contaminated sediment; establishment of shoreline buffer zones; monitoring; and institutional controls.  Dredging included removal of approximately 224,000 cubic yards of sediment spread over 22 acres of Styker Bay, smaller areas of Slip 6, Slip 7, and the navigational channel of the St. Louis River.  Capping and surcharging (temporary over-capping to consolidate sediments to improve water depth) were required in parts of Styker Bay.  Capping was required in Keene Creek Bay/Slip 7.  Shoreline buffer zones were required along the eastern shore of Stryker Bay, including all of the land on the Wisconsin side of the lake.

In 2010, following several years of work, the remedial actions for the Sediment Unit were substantially completed.  Operation and maintenance and long-term monitoring continue at the site.  A limited amount of work also remains for the state of Wisconsin portion of the site.

MPCA conducts Five-Year Reviews for the site.  The result of the most recent Five-Year Review in 2008 indicated that the Tar Seeps and Soil remedies were protective of human health and the environment in the short-term, although several areas needing followup were identified.  At the time of the review, the Sediments Unit work was still underway so no protectiveness determination was made for this part of the site.

U.S. Steel Site

In response to a request for response action from MPCA in 1983 and a 1985 Response Order by Consent issued by MPCA, U.S. Steel performed an investigation and feasibility study for the site.  In 1989, MPCA issued a ROD for the site.  The remedy divided the site into 18 units within three main management areas:  a Coke Plant Management Area, a Coke Plant Settling Basin Management Area, a Wire Mill Settling Basin Management Area, and several smaller areas not included in those areas. 

For the Coke Plant Management Area, the selected remedy included:  excavation and removal of tar, contaminated soil, and coking by-products, and placement into a on-site containment vault; discharge of contaminated water to the local sewer system for treatment; removal of solids from gas holders and placement in an off-site landfill, incineration, or place into an on-site vault, removal of PCB liquids and incineration at a commercial incinerator; land-spreading of ammonium sulfate and use as fertilizer on-site or off-site; and collection and disposal of drum contents by recycling, use as fuel, incineration, or placement in an on-site vault.  For the Coke Plant Settling Basin Management Area, the selected remedy included: completion of a PAH treatability study; institutional controls; construction of a containment (slurry) wall and capping of contaminated soil; water extraction and discharge to a sanitary sewer; top-dressing of dredge spoils; and rehabilitation of a culvert.  For the Wire Mill Settling Basin Management Area, the selected remedy included: completion of a PAH treatability study and institutional controls.  The overall site remedy also included monitoring of groundwater.  It did not include actions for the St. Louis River.

During the 1990's, multiple remedial actions were undertaken by U.S. Steel, including:  demolition and cleanup of the coke plant and related facilities; cleanup of a mercury spill; required field activities at the Mill Pond; removal of the wire mill and underground coke oven gas lines.  Of the actions required in the ROD, many are completed.  In some areas, waste were left in place above unrestricted use standards.  In all, 6,487 tons of sediment containing high levels of oils and grease, PAHs, and metals, were removed from the mill pond and transported to an industrial waste landfill.  The remaining contamination in the pond was covered and lined with geotextile fabric, backfilled with clean sand, and planted with native wetland vegetation.  Performance of surface water monitoring of the outfall continues on a semiannual basis.  At an area known as OU-J, approximately 10,000 cubic yards of coal tar and tar-contaminated soil were solidified in-place and a seven-foot-engineered cap was placed over the unit and vegetated.  Semiannual surface water monitoring of the unnamed creek that flows around OU-J continues and is used as the performance criteria.  As the OUs were completed, site buildings were dismantled as part of the site closure and incorporated in an onsite demolition landfill.  Two demolition landfills are present on site. 

MPCA conducts Five-Year Reviews of the U.S. Steel site.  The latest review, in 2008, identified several additional areas of concern at the site.  It also indicated that, although the cleanup actions to date have contributed to a decrease in risk to human health and the environment, significant contamination remains in soil, sediment, and surface water which exceeds regulatory criteria.  The review also noted that migration of contaminants to the St. Louis River is occurring.   Several OUs and areas of concern are not considered protective in the short-term due to remaining tar and contaminated soil, water, and sediments, and oil sheens. MPCA is working with the PRP for the site to address the additional areas of contamination and potential for remaining risks at the site. In addition to a risk evaluation and institutional controls, in order to assure the long-term protectiveness of the site, follow-up activities are expected in several areas, including repair of the OU-J and OU-K covers; investigation of oil sheen in OU-P; and revision of monitoring program and operation and maintenance plan.  A supplemental Remedial Investigation is underway by U.S. Steel to address these concerns.

Following further documentation of use impairments in the St. Louis River associated with the U.S. Steel site, from 2010 to 2012, U.S. Steel, EPA, and the State cooperated in conducting supplement investigatons and feasibility studies under the Great Lakes Legacy Act.  Future design work for a CERCLA-compliant sediment remedy is planned.

Property Reuse

Based on stakeholder group discussions and meetings about the U.S. Steel site, analyses of the site’s physical characteristics, contamination and remediation options, land use and market conditions in the city of Duluth and surrounding St. Louis County, the project’s consultant team worked with project stakeholders to develop a site reuse strategy, called a Conceptual Reuse Framework.  This framework is an early, flexible plan that will be able to incorporate additional detail and information as the remedy is implemented. The framework is also designed to allow for portions of the site to be adapted for reuse in different phases so that site reuses can benefi t the community as soon as possible. 

As the first step of site re-use, in 2010 a 120-acre area of the site was identified for potential reuse by the Duluth Port Authority as a light industrial park.  An accelerated supplemental investigation and cleanup design for this area is under development with oversight of MPCA.  


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

Community Involvement Coordinator, U.S. EPA
cheryl allen
(312) 353-6196




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