U.S. Steel Duluth Works was a fully integrated steel manufacturing plant built in 1907. The processes at the plant included coke production, iron and steel making, casting, primary rolling and roughing, hot and cold finishing, and galvanizing.
The plant began production in 1916 and continued operations until 1981. Within these 75 years the plant produced a variety of solid, semi-solid, and liquid wastes, some of which were discharged onto the surrounding land and into waterways. The Unnamed Creek (or Steel Creek) runs through the northern portion of the site and discharges into the St. Louis River. During operations much of the waste from the coke plant and the “hot side” of the plant was discharged into a settling basin that was located in the creek and then routed into the St. Louis River. The major contaminants were polycyclic aromatic hydrocarbons (PAHs) from coal tar. Wastes from the “cold side” of the plant were discharged directly into the river through the Wire Mill Settling Basin, which was built in 1954. A survey in 1973 found that the Wire Mill Settling Basin was full of sediment. The MPCA issued a NPDES Permit to monitor and control the effluent from the Wire Mill Pond. The stream water quality was found to exceed surface water standards for ammonia, cyanide, and phenols.
Water quality surveys were conducted by the state in 1928, 1948, and 1973. The results of these surveys showed a progressive deterioration in the water quality and biota of Spirit Lake and the St. Louis River estuary in the steel plant vicinity. The 1973 water quality levels in the St. Louis River exceeded the MPCA surface water standards for ammonia, cyanide, and phenols.
In 1979 the MPCA was informed of the company’s intent to close the coke and steel plant. By the end of 1988 a majority of the buildings on the site were demolished, by 1999 all but one of the remaining buildings were removed from the site. Currently, the only remaining building is a sewer shed near the site entrance plus a few roads, both paved and dirt paths, and concrete pads.
The Minnesota Pollution Control Agency (MPCA) requested a hydrological study of the U.S. Steel site in 1979. In response U.S. Steel submitted two reports; “Soil and Ground Water Investigation” in 1981 and “River Water Quality Impact Investigation” in 1983. The site was placed on the National Priorities List under CERCLA in 1983. A Request for Response Action was issued to U.S. Steel by the MPCA on October 3, 1983. The site was placed on the State of Minnesota’s Superfund listing in 1984. A Response Order by Consent was executed with the U.S. Steel Corporation by the MPCA on March 26, 1985. In the summer of 1985 the Remedial Investigation/Feasibility Study (RI/FS) was initiated, the buildings started to be demolished and a demolition landfill was built on-site. The Record of Decision (ROD) was signed in February 1989. 18 Operable Units (OU) were identified in the ROD and clean-up has been completed on sixteen. Two units remain the river sediments adjacent to the Wire Mill Pond and the coke settling basin. These units are in the remedial investigation process. See the OU Summary for specific clean-up actions.