Congressional District # 01
MIDCO IIEPA ID# IND980679559
Last Updated: February, 2012
Site DescriptionThe Midco II site is located in an industrial area near Gary, Lake County, Indiana. Midco II includes a 7-acre disposal area having highly contaminated groundwater, plus about 4-acres that include contaminated sediments, and additional highly contaminated groundwater. From January through August 1977, this site was used for the storage of waste solvents and other wastes in tanks and drums, storage of reclaimable materials, neutralization of acids and caustics, and dumping of wastes. In August 1977, a site fire consumed or damaged an estimated 50,000 to 60,000 drums.
The site is being addressed through a combination of federal and state actions and federal and state oversight of potentially responsible parties' (PRPs) actions.
Threats and Contaminants
Following removal of surficial wastes, the subsurface soil and groundwater were still highly contaminated. Contaminants affecting the groundwater include VOCs such as methylene chloride, benzene, toluene, trichloroethylene, tetrachloroethylene, and ethyl benzene (these are all liquids that easily evaporate); other organic compounds such as isophorone; metals such as arsenic, barium, chromium, nickel, copper and lead; and cyanide. The groundwater is so highly contaminated with salts that it can not be discharged to surface water after treatment. Sediments and soils are contaminated with similar substances as well as PCBs and polyaromatic hydrocarbons.
If no action was taken, direct contact with or accidental ingestion of contaminated groundwater, surface water, sediments, or soil would be a threat. Until the site is cleaned up, these risks are being controlled by a site fence, on-site staff, and a temporary soil cover. If no action was taken, migration of contaminants through the groundwater may threaten the offsite aquifer and downstream wetlands. Until the final remedy is in place, contaminated sediments may adversely affect wildlife and plants in or around the wetlands, but these sediments are not moving off-site, and the wetlands are of low value. There would be human health risks if the site or groundwater was developed in the future. This risk is being controlled through notices in the deed that restrict usage of the site.
1,4-dioxane was recently detected in the groundwater as a result of improved laboratory detection limits. In 2010 it was detected at 880 ug/l in on-site groundwater, and up to 630 ug/l in off-site groundwater.
In 1981, the United States Environmental Protection Agency (U.S. EPA) enclosed the site with a fence. From 1984 to 1989, U.S. EPA removed and disposed of all wastes on the site and excavated and disposed of contaminated soil and wastes from the sludge pit and filter bed. In 1985, a group of private parties entered an agreement with U.S. EPA to conduct sampling to locate the extent of soil and groundwater contamination, and to evaluate cleanup methods. The sampling and evaluation was conducted from 1985 to 1989.
In a 1989 decision document as amended in 1992, U.S. EPA decided that the cleanup should include:
- cleanup of the groundwater by pump and treat
- treatment and deep well injection of the treated groundwater into a saline aquifer
- treatment of an estimated 18,300 cubic yards of highly contaminated soil and sediments by soil vapor extraction and solidification/stabilization
- constructing a cap over the site.
In January 1992, private parties entered into an agreement with U.S. EPA to implement the cleanup, and formed the Midco Remedial Corporation (MRC). Construction started in 1993 with the consolidation of contaminated sediments onto the site and construction of the deep well. During 1994 to 1996, the MRC constructed and tested the pump-and-treat system, and in February 1996 initiated continuous operation. In December 1999, U.S. EPA determined that the pump-and-treat system was undersized. The MRC designed and constructed an expanded system, which started operating in February 2003. The pump-and-treat system may have to continue operating for many years to meet the groundwater cleanup action levels.
During 1993 to 1997, EPA and the MRC cooperated in conducting treatability studies for soil treatment by solidification/stabilization. Although soil vapor extraction 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 during 2000 to 2001, EPA allowed the MRC to test use of injection of chemicals to treat the subsurface soils, but the test results were not promising. In September 2004, U.S. EPA formally approved changes to the soil treatment requirements in the ROD, including:
- Adding use of the air sparging technology to remove VOCs from source area groundwater and soil below the groundwater;
- Increasing soil treatment by soil vapor extraction combined with air sparging to 79,200 cubic yards;
- Eliminating the requirement for treatment of organic compounds other than volatile organic compounds in the soils;
- reducing soil treatment by solidification/stabilization to 1,000 cubic yards of soil highly contaminated by metals and cyanide; and adding excavation and off-site disposal as an option for addressing these soils.
The MRC constructed part of the soil vapor extraction and air sparging system in October and November 2003, and conducted pilot testing of this portion of the system. The complete soil vapor extraction and air sparging system was constructed from October 2003 through December 2005, and the system started continuous operation in February 2006. The system was shut-down due to vandalism in June 2007. The MRC reconstructed the soil vapor extraction and air sparging system only for the most contaminated area of the site, and restarted the system in January 2008. The MRC focused its efforts on improving the performance of air sparging, which had been under utilized to that date, and eventually succeeded in getting nearly all of the air sparging wells operating with a substantial air flow rate. In March 2009, the MRC reinitiated sparging in all areas of the site. In September 2009, the MRC conducted soil gas sampling, which indicated that the required 97% reduction in VOC concentrations had been achieved, and that (except for vinyl chloride) VOC concentrations may be low enough to prevent groundwater contamination. Based on air emission data, it is estimated that the soil vapor extraction and air sparging system has removed about 14,000 pounds of VOCs from soil and groundwater. In 2010, the MRC performed a groundwater investigation to determine why some VOCs were still elevated in some pumping wells even though cleanup action levels were being achieved or approached in other areas, and found that significant VOC contamination remained in an area outside of the sparging system. In March 2011, the MRC expanded the air sparing system into this area. The MRC submitted a closure plan in October 2011 proposing a number of revisions to the cleanup. This plan is now under review. For the first time in 2009 - 2010, 1,4-dioxane was detected in groundwater at the site (up to 880 ug/l on-site and 630 ug/l off-site in 2010).
Following completion of the air sparging and soil vapor extraction, the highly contaminated soil will be excavated (or treated by solidification/stabilization) and the site cover will be installed. EPA completed five-year reviews in 1999, 2004 and 2009. In addition, to the need to implement air sparging in all areas of the site, the 2009 five-year review identified the need for monitoring fluoride levels in groundwater (fluoride was added to the 2009 groundwater analyte list), for additional institutional control work, and for adjustment to groundwater and soil cleanup action levels during site closure. The pump-and-treat system was temporarily shut-down in September 2010 to gather groundwater data under non-pumping conditions.
Success StoryThe soil vapor extraction and air sparging system has been successful in removing a large mass of VOCs from the soils and groundwater.
Usage of the site property is restricted by deed notices. In September 2007, the city of Gary passed an ordinance prohibiting installation of new wells for potable water usage, and all usage of the unconsolidated aquifers for potable water usage. The Gary-Chicago Airport has projections that include use of the Midco II property as part of the airport. In 2004, an Environmental Impact Statement was completed for the expansion of the airport, but this expansion does not include the Midco II property. It is possible that the site cover can be designed to accommodate the future development needs of the Gary-Chicago Airport.
ContactsRemedial Project Manager, U.S. EPA
pablo valentin (email@example.com)
Community Involvement Coordinator, U.S. EPA