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Record of Decision System (RODS)



City & State:  IDAHO FALLS  ID  83401
EPA ID:  ID4890008952
EPA Region:  10
NPL Status:  Currently on the Final NPL
ROD Type:  Record of Decision
ROD ID:  EPA/ROD/R10-93/057
ROD Date:  12/10/1992
Operable Unit(s):  04
Abstract:  The 1,700 by 1,900 feet USDOE Idaho National Engineering Laboratory (Operable Unit 4) is part of the 890-square mile U.S. Department of Energy (USDOE) facility located in Idaho Falls, Idaho. The primary mission of the Idaho National Engineering Lab (INEL) is nuclear reactor technology development and waste management. Land use in the area is predominantly industrial with mixed uses (restricted agricultural and recreational uses). The site, also known as the Test Reactor Area (TRA), contains more than 73 buildings and 56 structures such as tanks, cooling towers, laboratories, offices, and three high neutron flux nuclear test reactors, of which only one is currently operational. Approximately 7,700 people are employed at the INEL, with an estimated 600 employed at the TRA. Drinking water for the employees is obtained from production wells located within the facility. The site is contained within the northeastern portion of the Eastern Snake River Plain (ESRP), borders a floodplain to the west and north, and overlies the Snake River Plain Aquifer, which is a sole-source aquifer. The TRA was established in the early 1950s to operate and test high neutron flux nuclear test reactors. Prior to 1964, most of the chemical and radioactive wastewater generated during site operations was discharged directly to six wastewater ponds at the TRA. Use of these ponds has contributed to the formation and contamination of the Perched Water System. From 1964 until 1982, wastewater was injected directly into the Snake River Plain Aquifer, which did not contribute to the perched water contamination. Currently, there are four active disposal units that receive waste effluent generated at the TRA. These are the warm waste pond, which receives radiologically-contaminated wastewater; the cold waste pond, which receives primarily reactor cooling water with no radiological activity; the chemical waste pond, which is used for disposal of wastewater from ion exchange units and water softeners; and the sanitary waste ponds. Studies of the perched ground water and the Snake River Plain Aquifer, conducted by DOE, identified low-level contamination by VOCs, other organics, metals, other inorganics, and radionuclides. Previous 1992 RODS addressed sediment at the Warm Waste Pond, ordnance and contaminated soil, contaminated ground water at the Technical Support Facility, and contaminated sediment and sludge in the evaporation pond, discharge pipe, and waste sump as OUs 5, 23, 2, and 22, respectively. This ROD addresses the contaminated Perched Water System within the TRA, as OU4. Other 1993 RODs addresses the Perched Water System, the CFA Motor Pool Pond and Pit 9 of the Subsurface Disposal Area, as OUs 4, 9, and 18 respectively. Because public access to the TRA is restricted and the Perched Water System is approximately 50 to 150 feet below the ground surface, current public exposure to the perched water is unlikely. Furthermore, results of human health and ecological risk assessments demonstrate no unacceptable risk to human health and the environment. As a result, no remedial action is necessary for the Perched WaterSystem at the TRA; therefore, there are no contaminants of concern affecting this site.
Remedy:  SELECTED REMEDIAL ACTION: The selected remedial action for this site is no further action, with ground water monitoring. To support the no remedial action decision, DOE will begin a minimum 10-year decontamination and decommission period in the year 2007, when operations at the TRA have ceased; maintain existing institutional controls, including land use restrictions and property access restrictions; and replacing the existing warm wastewater pond, which is the major source of contamination in the perched ground water, with a new lined pond in 1993. Future contact with the Perched Water System also is unlikely because it is predicted to dissipate within about 7 years of ceasing disposal of wastewater to the ponds at the TRA according to modeling results. Results of human health and ecological risk assessments demonstrate no unacceptable risk due to potential future use. There are no costs provided for this no action remedy.

INSTITUTIONAL CONTROLS: Institutional controls, including land use restrictions, will be maintained to prevent site access during the 10-year period.
Text:  View full-text ROD [ 48K ]
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