First Five-Year Review Begins, Ogallala Groundwater Contamination Site, Keith County, Nebraska
The U.S. Environmental Protection Agency (EPA) conducts regular five-year reviews on Superfund sites where cleanups have been completed. These reviews are required by the Superfund law [42 U.S.C. § 9621(c)]. EPA Region 7 has initiated the first five-year review of the Ogallala Groundwater Contamination Site in Keith County, Nebraska.
The site consists of two distinct areas or operable units (OUs) located in the western part of Ogallala along the South Platte River. OU1 covers groundwater contamination along the business corridor of Highway 30. OU2 comprises an area of groundwater contamination that flows in an east-southeasterly direction, north of Highway 30 and east of West A and Fifth Streets.
Contamination at the site was discovered in 1989 when the Nebraska Department of Health detected chlorinated industrial solvents in Ogallala's water supply wells during routine sampling.
In 1993 the City of Ogallala developed a new public water supply well field, north of the contaminated area. Prior to the relocation of the city's wells, the site posed an immediate threat to public health through ingestion of contaminated groundwater. EPA, the Nebraska Department of Environmental Quality (NDEQ), and the potentially responsible parties (PRPs) have since implemented actions to control and reduce contaminant concentrations in groundwater.
In 1999 EPA issued a Record of Decision (ROD) for OU1 to address groundwater contamination. The actions included continued operation of a groundwater extraction and treatment system; land-use controls; and groundwater monitoring to determine if natural processes would address the residual contamination.
In 2000 a Consent Decree was lodged with the courts for the PRPs to perform the remedial actions selected in the 1999 ROD, to address groundwater contamination at OU1. In 2001 EPA initiated actions for OU2 to address contaminated soils and groundwater which included the installation of a soil vapor extraction system; monitoring of contaminant concentrations in soil; and monitoring of contaminant concentrations in the groundwater.
In 2002 EPA conducted a cleanup action for OU2 to remove chlorinated solvents from the groundwater. Work included 10 quarterly chemical oxidant injections and monitoring of contaminant concentrations in groundwater. In 2005 EPA completed a Remedial Investigation/Feasibility Study and in 2006 EPA issued a ROD for OU2 to address the groundwater contamination.
The ROD included quarterly chemical oxidant injections; land-use controls; a comprehensive well survey; and continued monitoring of contaminant concentrations in the groundwater. In 2008 the PRPs submitted documentation to support natural attenuation and in-situ chemical oxidation of OU1 groundwater contaminants. In-situ chemical oxidation involves the introduction of a chemical oxidant into the subsurface for the purpose of transforming groundwater contaminants into less harmful chemical species.
EPA continues to conduct quarterly chemical oxidation injections and monitoring at OU2. Efforts at OU2 have reduced contaminant concentrations in the downgradient portion of the plume.
This will be the first five-year review conducted for the Ogallala Groundwater Contamination Site. During this five-year review, EPA will evaluate the information for these ongoing actions and inspect the site to make sure it remains protective of human health and the environment. We encourage the community to tell us about site conditions or any concerns.
At the end of the review, a final report will be prepared and will be available in the site information repositories. The goal is to complete the review and report in June 2011.
Detailed site information is available at the following locations:
Goodall City Library
EPA Region 7 Records Center
If you have questions or need additional information on the Ogallala Groundwater Contamination Site or the five-year review process, please contact:
Community Involvement Coordinator
EPA Region 7
901 North Fifth Street
Kansas City, Kansas 66101
Toll free: 1-800-223-0425