Congressional District # 01
MIDCO IEPA ID# IND980615421
Last Updated: June, 2015
The 7-acre Midco I Superfund site is located at 7400 West 15th Avenue in Gary, Lake County, Indiana. The site is currently fenced and contains a groundwater treatment plant plus a contaminant source area and areas of contaminated sediment. The Midco I site was used to store, recycle, and dispose of industrial wastes from 1973 to 1979. In December 1976, a large fire destroyed an estimated 14,000 55-gallon drums of chemical wastes, resulting in spillage. Operations were resumed in October 1977. When the site was abandoned in 1979, thousands of full drums of waste were left behind in addition to the fire-damaged drums.
There are a number of small businesses located within 1,000 feet of the Midco I site. A residential neighborhood of Hammond, Indiana, is located within 1,500 feet and a residential neighborhood of Gary is located 3,000 feet from the site. Several private drinking water wells were found to have been drawing water from the same aquifer beneath the site and were located in the direction of off-site groundwater flow.
Site ResponsibilityThe Midco I site is being addressed by a combination of federal and state actions and federal and state oversight of potentially responsible party (PRP) actions.
Threats and ContaminantsFollowing removal of the surficial wastes in 1982, the subsurface soils and groundwater were still highly contaminated. Contaminants affecting the groundwater include volatile organic compounds (VOCs) such as trichloroethylene, tetrachloroethylene, vinyl chloride, benzene, methylene chloride, and toluene; other organic compounds such as phenol and isophorone; metals such as chromium, lead, and nickel; and cyanide. Groundwater sampling performed in 2009 and 2010 also identified significant groundwater contamination by 1,4-dioxane. The groundwater is so highly-contaminated with salts that it cannot be discharged to surface water, even after treatment.
Site soils and sediments contain the same contaminants present in the groundwater, but are also contaminated with polychlorinated biphenyls (PCBs), polyaromatic hydrocarbons (PAHs), and the pesticide chlordane. VOCs, chromium, lead, cadmium, and cyanide were detected in surface waters northeast of the site. Contaminants in the soil are leaching into the groundwater. If no action had been taken, direct contact with or accidental ingestion of contaminated groundwater, surface water, sediments, or soil would have been a threat to human health. Contaminated groundwater would also have migrated off-site and may have affected downgradient drinking water wells.
Until the site is cleaned up, these risks are being controlled by a site fence, on-site staff, and a temporary soil cover. Until the final remedy is in place, contaminated sediments may adversely affect wildlife and plants in or around the wetlands; however, these sediments are not migrating off-site and the wetlands are of low value. Because future development of the site or groundwater may pose human health risks, usage of the site is restricted through deed notices.
Cleanup ProgressIn 1981, the U.S. Environmental Protection Agency (EPA) enclosed the site with a fence. On-site wastes and the top foot of highly-contaminated soil were removed and disposed of in 1982. This action included removal of approximately 14,000 burned and crushed drums, 7,400 full drums, 10,000 gallons of liquid, and 8,000 gallons of sulfide-contaminated sludge from underground tanks. Another 840 drums were removed by a private party. In 1985, a group of private parties entered into an agreement with EPA to conduct sampling to locate the extent of soil and groundwater contamination and to evaluate cleanup methods. The sampling and evaluation was conducted between 1985 and 1989.
- In 1989 EPA issued a Record of Decision (ROD) that specified the cleanup actions needed at the site. EPA then issued a ROD Amendment in 1992 to change the remedy. Based on those two decision documents, the site cleanup was to include the following major components:
- Cleanup of the groundwater by a pump-and-treat system
- Treatment and deep well injection of the treated groundwater into a saline aquifer
- Treatment of an estimated 7,800 cubic yards of highly-contaminated soil and sediments by soil vapor extraction (SVE) and soil solidification/stabilization
- Construction of a cap over the site
In 1992, private parties entered into an agreement with EPA to implement the cleanup and formed the Midco Remedial Corporation (MRC). Construction began in 1993 with the consolidation of contaminated sediments onto the site and construction of the deep well. Between 1994 and 1996, the MRC constructed and tested the pump-and-treat system, and in 1997 initiated continuous operation of the system.
In 1996, EPA issued an Explanation of Significant Differences (ESD) to revise the standard for disposal of groundwater containing 1,1-dichloroethane by deep well injection and to update the chronic inhalation reference dose for that contaminant. In 1999, EPA issued ESD #2 to revise the standards for deep well injection of PAHs and to add or make corrections to the cancer potency factor for some of the site contaminants. In 1999, EPA also determined that the pump-and-treat system was undersized. The MRC designed and constructed an expanded system, which began operating in 2002. The pump-and-treat system was temporarily shut down in 2010.
Between 1993 and 1997, EPA and the MRC cooperated in conducting treatability studies for soil treatment by solidification/stabilization. Although SVE is well documented to be effective in removing VOCs from the soil, the treatability studies demonstrated that it would be difficult for solidification/stabilization to treat all of the other contaminants of concern. For that reason, in 2001 EPA allowed the MRC to test the injection of chemicals to treat the subsurface soils, but the test results were not promising. In September 2004, EPA issued ESD #3 which formally approved changes to the soil treatment requirements, including:
- Treating soils below the water table by construction of a groundwater barrier wall around the source area
- Lowering the water table within the source area by 12 feet
- Conducting SVE throughout the source area
- Eliminating the requirement for treatment of organic compounds other than VOCs in the soils
- Reducing soil treatment by solidification/stabilization to 3,560 cubic yards of soil highly contaminated by metals and cyanide
- Adding excavation and off-site disposal as an option for addressing highly-contaminated soils
The MRC constructed the groundwater barrier wall in late 2003. In 2004 and 2005, the MRC pumped out water within the barrier wall to lower the water table. This pumping continued as necessary during the soil treatment. The MRC constructed the SVE system in 2005 and continuous operation began in 2006. In August 2010, it was estimated that the SVE system had removed 50,000 pounds of VOCs. In July 2010, the MRC tested Midco soil gas, which was being used as an indicator for the soil contamination, and found that the SVE system had achieved the required 97% reduction in VOC concentrations. However, operation of the SVE system continued for another two years to further reduce soil and groundwater contamination. The SVE system was eventually shut down in May 2013. Outside the barrier wall, VOCs are near the groundwater cleanup actions levels for VOCs, but metals, cyanide, and sulfide contamination is significant.
In sampling conducted in 2009-2010, 1,4-dioxane was detected in groundwater for the first time (up to 140 ug/l outside of the groundwater barrier wall) because of improved detection limits. In September 2010, EPA approved a temporary shutdown of the groundwater pump-and-treat system so that groundwater monitoring could be performed under non-pumping conditions. This monitoring will be used to determine if monitored natural attenuation (MNA) could work as an alternate remedy for groundwater at the site.
EPA completed five-year reviews in 1999, 2004, 2009, and 2014. In the 2009 five-year review, EPA determined that additional work was needed on institutional controls and that adjustments to groundwater and soil cleanup action levels may be needed before site closure. On March 10, 2014, EPA completed the fourth five-year review for the site. The report concluded that the groundwater remedy for the site is protective in the short term and that the remedy for site sediments and soils will be protective once the remedial actions have been completed and institutional controls have been implemented.
Following completion of SVE in May 2013, the MRC conducted additional treatment and excavation of the remaining highly-contaminated soils and sediments that could not be addressed by SVE due to high levels of metals. The final design for the site soil cover was approved by EPA on August 28, 2014. The final soil cover construction work is projected to be completed by fall 2015.
In March 2015, EPA issued ESD #4 to make the following changes to the selected remedy:
- updating the inorganic contaminants of concern that are subject to groundwater cleanup outside the barrier wall, based on a statistical comparison of site-related data to background (up-gradient/side-gradient) data for inorganics;
- adding 1,4-dioxane as a groundwater contaminant of concern;
- documenting the temporary shutdown of the groundwater pump-and-treat system to allow a pilot study to evaluate the viability of MNA as an alternate groundwater remedy;
- adding the requirement for a two-foot cover over residually-contaminated sediments based on an assessment of the risks; and
- including the City of Gary, Indiana, ordinance prohibiting groundwater use for drinking purposes as an additional institutional control for the site.
EPA's removal action in the early 1980s was very successful in removing immediate chemical hazards to avoid significant health risks at the site.
Institutional controls such as deed notices are being used to restrict property re-use. In September 2007, the city of Gary passed an ordinance prohibiting the on-site installation of new wells for potable water usage as well as the use of the unconsolidated aquifer as a source of potable water. Gary has included the Midco I property within a redevelopment zone for the Gary-Chicago Airport.
ContactsRemedial Project Manager, U.S. EPA
pablo valentin (email@example.com)
Community Involvement Coordinator, U.S. EPA
AliasesMIDCO I SITE
MIDWEST SOLVENTS REC