1.1.1 Incident Category

Time-Critical

1.1.2 Site Description

The Ironwood Manufactured Gas Plant (MGP) Site is the location of a former coal gasification plant. Reportedly, the plant was constructed in 1911 and operated using a carbureted water gas (CWG) process.  A review of Sanborn maps indicates that the processes at the Site were consistent with typical CWG processes for the era. These processes generally included a first step in which coke or coal was heated in a closed vessel or retort into which steam was injected. A flammable gas mixture of methane and carbon monoxide was produced. In some cases petroleum products may have been applied to the heated mixture increasing the flammability of the resultant gas mixture. During these processes, a dense, oily liquid known as coal tar would condense out of the gas at various stages during its production, purification and distribution, and the coal tar would need to be either recycled in the process, sold, or otherwise disposed of. 

The plant continued operations and distribution of manufactured gas until the late 1950's when natural gas pipelines and service became more readily available in the area. By 1956 the plant was for sale and based on accounts of the Wisconsin Public Service Commission, by 1961 had discontinued service to Hurley, including the removal of meters following abandonment.

Interviews conducted by the Michigan Department of Environmental Quality (MDEQ) with local residents indicate that the buildings at the Site were removed prior to the gasometers (gas storage tanks). Based on the historical accounts, the surface structures at the Site were demolished and removed during the 1970's and the 1980's.  Following removal of the surface structures, the Site was reportedly used by the City of Ironwood for the storage of inoperable equipment and debris.

1.1.2.1 Location

The Site does not have a physical address but is located on the northwest corner of Hemlock Street and West Ayer Street in Ironwood, Gogebic County, Michigan

1.1.2.2 Description of Threat

The Site contains MGP waste material, such as coal tar and other process waste, that are the source of hazardous substances that have migrated and are migrating into soil, groundwater, surface water, and sediments of the Montreal River.  Contaminants of concern identified in soil, groundwater, surface water, and sediment include volatile organic compounds (VOCs), semivolatile organic compounds (SVOCs), polyaromatic hydrocarbons (PAHs) and inorganic contaminants.

1.1.3 Preliminary Removal Assessment/Removal Site Inspection Results

During bridge construction at West Norrie Street in 2010, construction crews identified visually contaminated soils suspected to be from the former Ironwood Manufactured Gas Plant site located approximately 700' upstream. MDEQ developed a Site Inspection Work Plan in 2010 to characterize conditions in the subsurface at the Site as well as in the surface water and sediment in the adjacent Montreal River.  The Site Inspection activities performed by the MDEQ were implemented with the intent of evaluating groundwater, surface water, and soil exposure pathways.

The results of the MDEQ’s Site Inspection indicated the presence of uncontrolled hazardous substances at the Site.  Gross tar and MGP process waste contamination was discovered in the surface and subsurface soil primarily located in the historical operating area of the Site, which contained VOC's, SVOC's, and inorganic contaminant concentrations exceeding the MDEQ Part 201 Residential Direct Contact Criteria (RDCC) and Groundwater Surface-water Interface (GSI).  Based on these findings, MDEQ requested assistance from USEPA.

USEPA conducted a site reconnaissance visit on November 19, 2010 to evaluate site conditions and to gather logistical information to assist in the development of a supplement site assessment plan.

A Supplemental Site Assessment was conducted during the week of April 9, 2012.  The Supplemental Site Assessment demonstrated that coal tar and other MGP waste remain buried at the Site in a visually discreet layer and that contaminants from this buried waste (volatile and semi-volatile organic compounds and inorganic compounds) are migrating into the groundwater and surface water (Montreal River). 

Significant Site Activities for this reporting period: 

• On August 30th, 2012, EPA and START began field screening suspected contaminated soil generated from the City of Ironwood's road construction project immediately adjacent to the site.  The soil piles had a slight odor to them, however, they had no visual contamination and the average PID head space samples were below the threshold established in the Soil Screening and Post Excavation plan for the site.  This material will be used on site as backfill or a solidifying agent for the disposal of coal tar material found during the excavation. 
• On September 4th, 2012, Excavation activities began on the northwest corner of the site near the Montreal River. Absorbent boom was deployed along the shoreline of the excavation area and downstream as a protective measure in the event of an accidrental release of waste material to the river. Excavation activities focused on removing the visual coal tar material found at the surface and removing any underlying coal tar material and distribution/drainage pipes found in the area.  In the excavation area, two 6" clay pipes were uncovered that contained a significant amount coal tar material.  In total, the coal tar was found at depths ranging from 5 to 10'.
• On September 5th, 2012, excavation activities continued in the northwest corner of the site.  The contaminated coal tar soil is about 5 feet below ground surface (bgs) and extends to about 10 feet bgs.  EPA attended the City of Ironwood's planning commission meeting to discuss potential restoration plans.  The City will provide EPA with comments on the post-removal surface restoration plan by September 21.
• On September 6th, 2012, trucking and disposal operations commenced.  An estimated 100 tons of contaminated coal tar soil was transported to the K&W landfill in Ontonagan, MI for disposal.  Excavation activities moved to the northeast corner of the site near the location of the MGP processing building.  Crews were able to identify the foundation of the building and determined that there is little soil contamination north of the MGP processing building foundation.  While removing the building's foundation, crews uncovered a 2,000 gallon vat of coal tar residuals underneath the building.  Samples of the coal tar material were taken and sent to a laboratory for analysis.   

During this reporting period:

U.S. EPA: 2 (Halbur, Hassan)
START (Weston): 2
ERRS (LATA-Kemron & CMC): 8

www.epa.gov/region5/cleanup/ironwood

www.epaosc.org/ironwoodmgp

www.epa.gov/region5/cleanup/ironwood

www.epaosc.org/ironwoodmgp