PCB OU - PCB Areas Operable Unit

This OU consists of 4 sites totaling approximately fifty acres within the Crab Orchard National Wildlife Refuge. The Record of Decision (ROD), August 1990, documented contamination of PCBs, heavy metals (lead and cadmium) and organic compounds (trichloroethylene (TCE)) as a result of past industrial practices. Schlumberger entered into a settlement agreement to conduct remediation. Schlumberger completed incineration of approximately 65,412 cubic yards of PCB-contaminated soil containing concentrations greater than 25 parts per million (ppm) in June 1997. Some 102,660 cubic yards of contaminated soils containing less than 25 ppm PCBs along with the incinerator ash were disposed in an on-site 3-acre repository. Incinerator ash containing hazardous levels of lead were stabilized and disposed of in an engineered 2-acre on-site landfill.

It was discovered that groundwater at 2 sites is contaminated with solvents including TCE above regulatory standards. In June, 2000, USEPA issued an Explanation of Significant Differences (ESD) to the PCB OU. The ESD selected multi‑phase extraction of chlorinated solvent contaminated groundwater, with limited phytoremediation and monitored natural attenuation, as the remedial technology to address the groundwater contamination. The results of the pilot test conducted as part of design studies indicate that multi‑phase extraction will not be effective in significantly reducing TCE contamination at the site. USEPA issued an Amendment to the Record of Decision on August 7, 2007 to select a new remedy for two of the three contaminated groundwater plumes (Plumes 1 and 3). A second ROD Amendment for Plume 2 is forthcoming.

PCB OU Overview Map (710 KB PDF file)

Acronyms

The following documents can be found at:

Southern Illinois University (618) 453-2818

McLafferty Annex

1830 University Press Drive

Carbondale, Illinois 62901

Hours: Monday - Friday 9:00 a.m. - 5:00 p.m.

U.S. Fish & Wildlife Service (618) 997-3344

Crab Orchard National Wildlife Refuge

6987 Headquarters Road

Marion, Illinois 62959