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Congressional District # 6


EPA ID# ILD980824031
Last Updated: May, 2015

Site Description

The Kerr-McGee Sewage Treatment Plant site is one of four National Priorities List (NPL) sites in the West Chicago area that was contaminated with radioactive thorium wastes. The radioactive waste originated from a nearby facility known as the Rare Earths Facility (REF).  The REF, operated by Lindsay Light and Chemical Company and its successors from 1932 until 1973, produced non-radioactive elements known as rare earths and radioactive elements such as thorium, radium, and uranium along with gas lantern mantles for private entities and the United States government's use in federal atomic energy programs.  The REF produced these elements by extracting them from monazite sands, bastnasite (rare earth ore), and other ores, using an acid leaching process.  Production of these elements resulted in the generation of radioactive mill tailings that contained residual levels of thorium, radium, and uranium as well as certain other insoluble metals.  Kerr-McGee (now known as Tronox) purchased the REF in 1967 and maintained operations until closing the facility in 1973.

The Sewage Treatment Plant site consists of the West Chicago Sewage Treatment Plant (STP) property which covers approximately 25 acres of land (STP Upland Operable Unit), plus approximately 1.2 miles of the West Branch DuPage River from the northern boundary of the STP downstream to the river's confluence with Kress Creek (STP River Operable Unit). The STP property became contaminated when radioactive thorium mill tailings from the REF were used as fill material in and around the property or disposed in a historical landfilled area on the facility. The river portion of the site became contaminated when radioactively-contaminated soils at the facility or on the banks of the river eroded into the river and were deposited in river sediments.  U.S. EPA estimates that approximately 5 acres in and along the river were contaminated, for a total site acreage of approximately 30 acres.

Approximately 15,000 people live within three miles of the site.

Site Responsibility

This site was addressed through federal and potentially responsible party (PRP) actions.  After successful cleanup of the site, the Kerr-McGee Sewage Treatment Site was deleted from the National Priorities List on April 21, 2013.

Threats and Contaminants

Soils and sediments at the site contained low-level radioactive contamination. People who are exposed to radioactively-contaminated soils or sediments may suffer adverse health effects.

Cleanup Progress

U.S. EPA began a remedial investigation/feasibility study (RI/FS) in 1993 to determine the nature and extent of contamination at the site and to evaluate various cleanup alternatives.  Around 1997, Kerr-McGee and parties representing the affected communities asked U.S. EPA for time to negotiate an agreement regarding cleanup of the site.  U.S. EPA gave the parties time to negotiate during which Kerr-McGee conducted additional characterization work at the site and the parties eventually reached a conceptual agreement for cleanup of the site.  The proposed cleanup approach was contingent upon Kerr-McGee, U.S. EPA, and other governmental agencies resolving certain technical and legal issues regarding the cleanup.

In October 2003, the federal government and Kerr-McGee reached a non-binding agreement in principle which resolved the main outstanding technical and legal issues regarding the proposed cleanup approach.  The agreement in principle also described the steps that would have to occur for Kerr-McGee and the government to reach a formal, binding agreement, known as a Consent Decree, for site cleanup.

Following the agreement in principle, Kerr-McGee and U.S. EPA signed an Administrative Order on Consent, effective October 16, 2003, for Kerr-McGee to conduct a time-critical removal action at the STP Upland Operable Unit.  Kerr-McGee began cleanup work at the site in October 2003 and completed excavation work in December 2004, removing 6,557 cubic yards of contaminated soil from the site.  Final restoration work at the Upland Operable Unit was completed during 2006 in conjunction with cleanup work at the adjacent River Operable Unit (discussed below).

Also following the agreement in principle, Kerr-McGee and U.S. EPA signed an Administrative Order on Consent, effective November 21, 2003, for Kerr-McGee to complete the RI/FS at the site which were finalized in May 2004.  The FS report evaluated cleanup alternatives for the STP River Operable Unit but not the STP Upland Operable Unit, because the time-critical removal action at the upland area was already removing the thorium contamination from that portion of the site.

A September 30, 2004 Record of Decision (ROD) selected excavation and off-site disposal as the cleanup method for targeted sediments and soils at the STP River Operable Unit.  The ROD also determined that no further action was necessary at the STP Upland Operable Unit after completion of the time-critical removal action at that portion of the site.

Under the March 30, 2005 federal Consent Decree, Kerr-McGee agreed to design and carry out the cleanup at the STP River Operable Unit, with the cleanup estimated to cost $1.8 million.  Although the consent decree was not yet finalized, U.S. EPA allowed some of the cleanup work to begin at the upstream portion of the river in November 2004, and Kerr-McGee removed 562 cubic yards of contaminated soil from the site before shutting down for the winter.  The cleanup of the upstream portion of the river (Reach 5A, from the STP to Gary’s Mill Road) was completed during the summer of 2005.  The cleanup of the downstream portion of the river (Reach 5B, from Gary’s Mill Road to the confluence) began in August 2006 and was completed in the fall of 2006.  Some additional restoration work in Reach 5B (i.e., certain plantings) was completed in spring 2008.

With the completion of the cleanup work in Reach 5B of the river, all areas of the Sewage Treatment Plant Site have now been cleaned up.  U.S. EPA signed a preliminary close-out report for the site in September 2006. 

In January 2009, Tronox (formerly Kerr-McGee) filed for Chapter 11 bankruptcy.  As a result of the bankruptcy settlement, a Trust was set up to complete the cleanup and monitoring for the four West Chicago Kerr-McGee Superfund sites.  The Trust has been conducting maintenance and monitoring activities for the STP site since February 14, 2011.

On August 11, 2011, a final inspection was conducted to determine whether the STP site was complete and the maintenance and monitoring requirements had been successfully achieved.  A punchlist of final items to be completed was generated, and these actions were accomplished in the spring of 2012.  A Certification of Completion was then issued by EPA in September 2012, and a Final Closeout Report was completed for the site. 

On February 20, 2013 EPA published its Notice of Intent to Delete the Kerr-McGee Sewage Treatment Plant from the NPL.  That deletion became final on April 21, 2013.

Community Involvement

The local community has been very involved in site issues for more than a decade. The Thorium Action Group (TAG) is a very active and vocal community group that has fought hard for the removal of the thorium materials from the West Chicago and DuPage County area. EPA participated in regular meetings of the West Chicago Intergovernmental Forum, which included representatives of state and federal regulatory agencies, local community representatives, members of TAG, the PRP, and other interested stakeholders.

In addition, the local community entities (including West Chicago, Warrenville, DuPage County, the DuPage County Forest Preserve District and the West Chicago Park District) entered into a separate consent decree with Kerr-McGee regarding the cleanup of the site, and have retained a technical representative who is conducting daily oversight of the cleanup on behalf of the local communities.

On May 24, 2004, U.S. EPA issued for public comment a proposed plan for site cleanup. U.S. EPA held a public meeting on June 2, 2004, regarding the proposed cleanup plan and responded to comments received from the community.

Property Reuse

The STP Upland Operable Unit consists of the grounds of an operating sewage treatment plant.  Future land use is expected to remain the same.

The STP River Operable Unit consists of about 1.2 miles of river adjacent to the sewage treatment plant property, residential properties, and forest preserve property.  Future land use is expected to remain the same.

There are no restrictions on the future use of the property because the site was cleaned up to unrestricted cleanup standards.


Remedial Project Manager, U.S. EPA
david seely (seely.david@epa.gov)
(312) 886-7058

Community Involvement Coordinator, U.S. EPA
janet pope
(312) 353-0628




Site Profile Information

This profile provides you with information on EPA's cleanup progress at this Superfund site.


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