St. Louis River-U.S. Steel Superfund Site: Operable Unit (OU) Summary

An operable unit (OU) is a regulatory term meaning a portion of a site that is investigated and cleaned up separately from other portions of the site. Dividing a site into two or more operable units allows separate investigations and cleanups to proceed at their own pace. Common examples are investigating soil and groundwater contamination separately, and cleaning up and redeveloping small portions of a larger site.

OU Summary

Operable Unit Summary Map

OU-A Tar and Tar Contaminated Soil

In September 1994, U.S. Steel placed a contract with 7 & 7, Inc. to remove Operable Unit A tars. Recyclable material was shipped to 7 & 7's facility in Ohio for recycling. Nonrecyclable tar and debris were disposed off-site. As of March 1995, all the identified tar spills were excavated and removed from the site. Confirmation samples were collected from the materials handling yard spill area, the Wire Mill Pond spill area, the southwest tar spill area, the fuel oil storage tank spill area, and the ravine embankment spill area. Approximately 8,780 tons of materials were shipped off-site to the BFI Landfill near Madison, Wisconsin. Approximately 338 tons were recycled at the 7 & 7 recovery facility in Wooster, Ohio. Final site restoration was completed in October 1995.

OU-A Map

OU-B Contaminated Water in Tanks and Pipelines

Water was pumped from tanks and basements as part of remedial work performed during 1985, 1988, 1989. In 1985, 1988, and 1989 the water was passed through a baffled clarifier on-site before being discharged to the sanitary sewer for treatment at the Western Lake Superior Sanitary District plant.

OU-B Map

OU-C Solids in Large and Small Gas Holders

Based upon the analytical results of samples collected from the large and small gas holders, from October through December 1993, a total of 1,148 tons of large gas holder solids were removed and shipped to a hazardous waste landfill in Belleville, Michigan; and a total of 66 tons of small gas holder solids were shipped to a special waste landfill in Clinton, Illinois.

OU-C Map

OU-D Tar and Coking By-Products in Tanks

Twenty-three tanks were emptied and cleaned during remedial work performed in 1985. The residual contents from these tanks were recycled as fuel. Twenty tanks were emptied and cleaned during remedial work performed in 1988. The residual materials from these tanks were used as fuel or disposed of by 7 & 7, Inc. as described with Operable Unit A.

OU-D Map

OU-E Tars and Coking By-Products in Pipelines

Pipelines were dismantled and cleaned as part of the remedial work performed in conjunction with the 1989 demolition of the coke plant facility. The clean pipes were transported from the site as scrap metal. The tars and coking byproducts removed from the pipes were placed with other fuel materials in the temporary staging areas on-site. A portion of the underground pipes were excavated and cleaned in 1992, with tar stored at the site and cleaned pipe being disposed as scrap metal. The remaining materials were used as fuel or disposed as described with Operable Unit A. USX submitted a response action plan in March 1999 that addressed the removal, cleaning and disposal of the remaining 7,800 feet of buried coke oven gas lines. The response action plan was approved by the MPCA in April 1999. Removal operations were completed in August 1999.

OU-E Map

OU-F PCB Liquids

PCB liquids were removed from three PCB transformers during the spring and summer of 1989. The drained transformer carcasses were transported from the site with the PCB liquids in the fall of 1989. The PCB liquids and transformer carcasses were transported to General Electric Company's facility in Chicago, Illinois and incinerated.

OU-F Map

OU-G Ammonium Sulfate

The sulfate storage room contained a couple small stockpiles of ammonium sulfate. The material was removed and recycled, in two batches, prior to June, 1993. The first batch was brought to Holiday Greenhouse in Superior, Wisconsin for use as fertilizer. The second batch was delivered to an individual for use in agricultural applications.

OU-G Map

OU-H Lubricants, Paints Solvents, Fuel Oils, Water, Metal Shavings

A majority of drums and containers were collected and placed temporarily in reinforced concrete containment cells. The contents of the drums were identified and appropriately disposed of during the winter of 1989-90. The remaining drums scattered about the surface of the site were collected, the contents identified, and disposed of during the summer of 1992. Partially buried drums in 10 areas of the site were investigated in 1992 using geophysical methods. The drums were excavated, contents identified, and were shipped off-site in 1993 for use as fuel, incineration (PCBs), or for treatment to neutralize the alkalinity. Contaminated soil and debris excavated during removal of the drums were disposed of at a hazardous waste landfill.

OU-H Map

OU-I Non-Native Material in Settling Basin

The February 1989 Record of Decision (ROD) designates the “no action” alternative which includes routine inspections and water quality monitoring to verify the long-term effectiveness. This “no action” response was subject to the completion of the PAH treatability study (completed and approved June 1990) that found no innovated treatment technologies were applicable. Based on further investigation in 2008-2010, US Steel has agreed to address the non-native sediments in both the Steel Creek and Wire Mill Pond aquatic sediment units.

OU-I Map

OU-J Tar and Tar Contaminated Soils

U.S. Steel retained Geraghty & Miller, Inc. to re-evaluate four alternatives for Operable Unit J, including a slurry wall containment system, a slurry wall system with in-situ treatment, in-situ cement stabilization, or a funnel and gate system. A Response Action Plan (RAP) for Operable Unit J was submitted to MPCA in March of 1996 and proposed in-situ cement stabilization as the preferred remedy. The MPCA approved the RAP in November 1996. Field work commenced in June 1997 and was completed in December 1997. 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. Semi-annual monitoring of the Unnamed Creek that flows around OUJ continues on a semi-annual basis.

OU-J Map

OU-K Dredge Spoil Material

The ROD designates top dressing of the cells of dredge spoil material including the rehabilitation of the culvert beneath the dredge spoil material. This response action was subject to the completion of the PAH treatability study (completed and approved June 1990) evaluating the implementation of alternative and innovative treatment technologies. The report found no innovative treatment technologies were applicable.

OU-K Map

OU-L Stream Channel

The ROD designates the same “no action” alternative for this operable unit as for Operable Unit I above. Based on further investigation in 2008-2010, US Steel has agreed to address the non-native sediments in both the Steel Creek and Wire Mill Pond aquatic sediment units.

OU-L Map

OU-M Delta and Stream Channel area

The ROD designates the same “no action” alternative for this operable unit as for Operable Unit I above. Based on further investigation in 2008-2010, US Steel has agreed to address the non-native sediments in both the Steel Creek and Wire Mill Pond aquatic sediment units.

OU-M Map

OU-N Unnamed (Steel) Creek Estuary

The ROD designates the same “no action” alternative as for Operable Unit I; however, post-ROD sampling of estuary sediments showed that sediments were being reworked by wave and storm events, resulting in a continuing source of contaminants to the St. Louis River. U.S. Steel has agreed to address the non-native sediments in both the Steel Creek and Wire Mill Pond estuaries.

OU-N Map

OU-O Spit of Land

The ROD designates the same “no action” alternative as for Operable Unit I above.

OU-O Map

OU-P Wire Mill Pond

A Response Action Plan was submitted to the MPCA in March 1996 and approved by the MPCA in November 1996. Response actions commenced in June 1997 and were completed in December 1997. In all, 6,487 tons of sediments containing high levels of oils and grease, PAHs and metals were removed and transported to an industrial waste landfill. The pond was lined with geotextile fabric, backfilled with clean sand and planted with native wetland vegetation. Performance monitoring of the outfall continues on a semi-annual basis. Based on further investigation in 2008-2011, US Steel has agreed to address the non-native sediments in both the Steel Creek and Wire Mill Pond aquatic sediment units.

OU-P Map

OU-Q Dredge Spoil Area

The ROD designates the “no action” alternative as for Operable Unit I above. Based on further investigation in 2008-2011, US Steel has agreed to address the non-native sediments in both the Steel Creek and Wire Mill Pond aquatic sediment units.

OU-Q Map

OU-R Wire Mill Pond Delta (sediments under water)

See Operable Unit N (Unnamed Creek Estuary) above. Based on further investigation in 2008-2011, US Steel has agreed to address the non-native sediments in both the Steel Creek and Wire Mill Pond aquatic sediment units.

OU-R Map

OU-S Cement Slag

Soil with high pH levels exists and evidence of trespassing, including dust generating activities such as motorcycling and four-wheeling was noted. US Steel has agreed to address the non-native soils.

 

Additional components not identified by an Operable Unit

Operable Unit Summary Map

Tar and Tar Contaminated Soil in the Coke Plant Settling Basin Located between (but not included in) Operable Unit I and J

The response action in the ROD stated that this contaminated material was to be excavated and used as fuel. No specific reference is found regarding the remediation of this area. Based on further investigation in 2008-2011, US Steel has agreed to address the non-native sediments in both the Steel Creek and Wire Mill Pond aquatic sediment units.

OU-I & J Map

Soils Contained by Above and Below Ground Petroleum Storage Tanks

Soil samples were collected from below each tank and were tested for contamination. The lightly-contaminated petroleum-based fuel oil and gasoline were decontaminated by thin spreading on-site or removed for off-site disposal.

Map

Mercury Cleanup

Free liquid mercury was discovered on the ground below old floor planking at the former location of the meter storage shed located between the Coke Gas Holder and the North Boiler House. Approximately 40 fluid ounces of free mercury was recovered during the 1993 cleanup. The cleanup was conducted in two phases, phase I was the cleanup of visible mercury and phase II was the excavation of mercury contaminated soils.

Mercury Map

On Site Demolition Landfills

Demolition Landfill #1 was permitted to accept building masonry from the demolition of the Atlas Cement Plant.

Demolition Landfill #2 was permitted to accept building masonry from the demolition of the steel facility.

Demolition Landfill #3 was presented in the ROD as an alternative disposal location for the gas holder solids, ammonium sulfate and other items. The landfill was never permitted due to concerns of a buried basement that contained oily waste.