Congressional District # 01
MIDCO IIEPA ID# IND980679559
Last Updated: June, 2015
Site DescriptionThe Midco II site is located in the city of Gary, Lake County, Indiana. It is located in a predominantly industrial area where 34 other potential hazardous waste sites have been identified. The site occupies approximately 7 acres of sandy soil and fill, contaminated groundwater, and ditch sediments located at 5900 Industrial Highway. The original ridge and swale topography was filled in with industrial wastes to create a relatively flat surface during the 1950s and 1960s. The site is 1.14 miles south of Lake Michigan and 0.85 miles north of the Grand Calumet River.
Midco II was used for temporary bulk liquid and drum storage of waste materials, neutralization of acids and caustics, and dumping of wastes. These operations began in 1976 following a fire at the Midco I facility. In 1977, an additional fire at Midco II destroyed equipment, buildings, and an estimated 50,000 to 60,000 drums containing chemical wastes. This resulted in additional spillage across the site and contamination of the soil and groundwater.
The site is being addressed through a combination of federal and state actions and federal and state oversight of potentially responsible party (PRP) actions.
Threats and Contaminants
Following removal of surficial wastes, the subsurface soil and groundwater were still highly contaminated. Contaminants affecting the groundwater include volatile organic compounds (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 (PAHs).
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 off-site 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.
The contaminant 1,4-dioxane has been 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 at up to 630 ug/l in off-site groundwater.
In 1981, the U.S. Environmental Protection Agency (EPA) enclosed the site with a fence. From 1984 to 1989, 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 EPA to conduct sampling to locate the extent of soil and groundwater contamination, and to evaluate cleanup options. The sampling and evaluation was conducted from 1985 to 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 18,300 cubic yards of highly-contaminated soil and sediments by soil vapor extraction (SVE) and 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 1996 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 factors 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 2003. 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 2000-2001, 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:
- Adding use of the air sparging technology to remove VOCs from source area groundwater and soil below the groundwater table
- 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 VOCs in the soils
- Reducing soil treatment by solidification/stabilization to 1,000 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 part of the SVE and air sparging system in late 2003, and conducted pilot testing of this portion of the system. The complete SVE and air sparging system was constructed from October 2003 through December 2005, and the system started continuous operation in 2006. The system was shut down due to vandalism in June 2007. The MRC reconstructed the SVE and air sparging system only for the most contaminated area of the site, and restarted the system in 2008. The MRC focused its efforts on improving the performance of air sparging, which had been underutilized 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 SVE and air sparging system 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. 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). In September 2010, EPA approved a temporary shutdown of the 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 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. On March 11, 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 soil and sediment 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 soil cover construction work is projected to be completed by fall 2015.
EPA anticipates issuing ESD #4 in summer 2015 to address some additional remedy changes for the Midco II site.
Success StoryThe soil vapor extraction and air sparging system was 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.
ContactsRemedial Project Manager, U.S. EPA
pablo valentin (firstname.lastname@example.org)
Community Involvement Coordinator, U.S. EPA