1.1.1 Incident Category

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 contained MGP waste material, such as coal tar and other process waste, that were the source of hazardous substances that migrated 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), polycyclicaromatic 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). 

• Installed and developed four on-Site groundwater monitoring wells
• Recovered COIR logs misplaced by flood
• Added boulders and additional riprap to bank of Montreal River
• Completed final grading of the Site, including two drainage swales
• Received and spread topsoil to cover Site
• Seeded Site with fescue blend (per City's requested Restoration Plan) and covered with straw
• Installed restoratioin matting along bank and drainage swales
• Replaced silt fence
• Planted native trees donated by US Forest Service
• Repaired temporary perimeter fencing
• Conducted perimeter air monitoring and implemented dust control measures
• Conducted part-time overnight security
• Demobilized equipment and personnel from Site

 2.1.2 Enforcement Activities, Identity of Potentially Responsible Parties (PRPs)

The City of Ironwood is the former owner and operator of the Ironwood Gas Works and is the only PRP for this Site.  The City does not have the ability to conduct the clean-up, but is assisting by contributing in-kind services. 

2.1.3 Progress Metrics 

See previous POLREPS for summary of waste generated during initial mobilization.  During this mobilization, only a small amount of IDW (soil and water) was generated during installation of the groundwater monitoring wells.  Two drums of coal tar impacted soil was transported to K&W Landfill in Ontonagon, MI for disposal.  The water was accepted by the Ironwood POTW.

The Site experienced significant flooding during this reporting period, as described earlier in this POLREP.  There was an attempted break-in of the equipment the first night of the mobilization.  The City responded with additional police patrols and EPA initiated part-time overnight security.

The following equipment was used during the reporting period:

2 - pickup trucks

1 - bull dozer

1 - skid steer
1 - water tank (dust control)

1 - drill rig
3 - DataRams with Viper

CMC driver and delivery equipment stayed on Site due to short mobilization time.

During this reporting period:

USEPA: 1 (Halbur)
START (Weston): 1
ERRS (LATA-Kemron & CMC): 5

www.epa.gov/region5/cleanup/ironwood

www.epaosc.org/ironwoodmgp

www.epa.gov/region5/cleanup/ironwood

www.epaosc.org/ironwoodmgp