Chemical Oxidation Remediation to Begin, 10th Street Superfund Site, Columbus, Nebraska
On January 22, 2007, the U.S. Environmental Protection Agency (EPA), will start chemical oxidation remediation for the 10th Street Superfund Site in Columbus, Nebraska. The activities will last approximately one month, and will occur along 20th Street generally between 22nd and 24th Avenues. After the chemical injections, sampling will be performed at regular intervals to monitor the concentrations of the contamination, and determine if the levels of chemicals injected are correct. After a period of approximately six months, more injections will take place.
The 10th Street Site is located in the south-central portion of the city of Columbus in Platte County, Nebraska. The site was originally defined as those municipal drinking water wells which contain, or have contained, volatile organic compounds (VOCs), mainly trichloroethylene (TCE) or tetrachloroethylene (PCE), and certain areas containing VOC-contaminated soil which may be a source of ground water contamination. Arsenic contamination has also been detected throughout the duration of EPA's involvement with the site.
The site came to the attention of the Nebraska Department of Health in November 1983, when trihalomethanes, a group of VOCs created as a by-product of chlorination, were detected during a routine sampling event. Follow-up sampling detected TCE in four of the municipal wells. The site was proposed to the National Priorities List (NPL) in 1989, and was officially listed on the NPL in August 1990.
A site investigation was begun in 1988. A Remedial Investigation/ Feasibility Study (RI/FS) was conducted from 1990 through 1992. In February 1995, EPA issued a Record of Decision (ROD) which called for ground water monitoring with institutional controls, with a contingency for extraction and discharge to the Loup River if the ground water monitoring results indicated unacceptable risks. At the time of the ROD, the sole source was thought to be some small dry cleaners in the vicinity of the municipal wells.
Ground water monitoring conducted after issuance of the ROD detected elevated concentrations of PCE and TCE in a monitoring well that had previously been considered a background well for the site. A subsequent site investigation conducted in the fall of 1998 indicated a major source of PCE and TCE ground water contamination emanating from a dry-cleaning facility located over 1/2 mile upgradient from the original site. EPA conducted four phases of a Removal Assessment to investigate the extent of ground water contamination. EPA implemented a removal action which included an Air Sparging/Soil Vapor Extraction (AS/SVE) system to address soil and ground water contamination at the dry-cleaning facility source area. EPA completed a second RI/FS to delineate the extent of contamination and evaluate alternatives to address the contamination. EPA finalized an interim remedial action ROD on September 20, 2001, that included extraction of contaminated ground water at municipal well W-1, plume interception by extraction wells, treatment and discharge of contaminated ground water, and continued operation of the AS/SVE system. The ground water extraction and treatment (GET) system was designed, constructed, and is currently in operation.
The site is being managed by separate operable units (OUs). OU 1 refers to the first RI/FS, the 1995 ROD, and all actions conducted prior to discovery of the second ground water plume. OU 2 refers to all actions conducted to investigate and address the second plume of contamination, including the AS/SVE removal action and the second RI/FS. RI/FS activities continued through the implementation of the interim remedial action. In May 2005, EPA prepared another FS to identify and evaluate remedial alternatives for the final remedial action. As indicated in the September 2005 final ROD, the final remedy calls for continued operation of the GET and AS/SVE systems, limited action for contaminated soils in the original source areas and chemical oxidation in the plume located upgradient of the GET.
Site-related documents provide details of the nature and extent of contamination and the work that has been completed at the 10th Street site. These documents are part of the Administrative Record File, available during normal business hours at the following locations:
Columbus Public Library
2504 14th St.
EPA Region 7
901 N. Fifth St.
Kansas City, Kansas
If you have questions or need additional information, please contact:
Community Involvement Coordinator
EPA, Region 7,
Office of External Programs
901 N. Fifth St.
Kansas City, Kansas 66101