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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/R10-94/084
ROD Date:  09/27/1994
Operable Unit(s):  19
Media:  Groundwater, soil
Contaminant:  Chromium, mercury, cesium-137, cobalt-60, barium, copper, nickel, silver, zinc, ethyl benzene, TCE, PCE, xylenes
Abstract:  Please note that the text in this document summarizes the Record of Decision for the purposes of facilitating searching and retrieving key text on the ROD. It is not the officially approved abstract drafted by the EPA Regional offices. Once EPA Headquarters receives the official abstract, this text will be replaced.

The 2,305 square kilometer Idaho National Engineering Laboratory (INEL), a government facility managed by the U.S. Department of Energy, is located 32 miles west of Idaho Falls, Idaho. Current land use at the INEL is primarily nuclear research and development and waste management. Surrounding areas are managed by the Bureau of Land Management for multipurpose use. The developed area within the INEL is surrounded by a buffer zone used for cattle and sheep grazing. The INEL property is located on the northeastern edge of the Eastern Snake River Plain, a volcanic plateau, that is primarily composed of silicic and basaltic rocks and relatively minor amounts of sediment. The depth to the Snake River Plain Aquifer underlying the facility varies from 61m (200 ft) in the northern portion to 274.3m (900 ft) in the southern portion of the INEL. Regional groundwater flow is generally to the southwest. 100 out of 11,700 people from INEL are employed at the Radioactive Waste Management Complex (RWMC).

Contamination at the site includes two areas: Pad A and the Naval Reactors Facility (NRF). Pad A is located in the north-central portion of the Subsurface Disposal Area (SDA), an 88-acre disposal area located within the RWMC. Surface water is present at the RWMC only during periods of heavy rainfall or snowmelt, which generally occur in January through April. To minimize the potential for surface water to flow onto the RWMC during periods of high surface water runoff at the INEL, water is diverted from the RWMC via spreading areas and associated dikes, located to the west and south of the RWMC. The NRF is located on the west-central side of the Idaho National Engineering Laboratory, outside the perimeter OU 8-07. Also located on NRF are an industrial waste ditch (IWD) and landfill units.

The Naval Reactors Facility was established in 1949 as a testing site for the naval nuclear propulsion program. The Submarine Thermal Reactor Prototype (SIW) became operational in 1953. At that time, the first section of the Industrial Waste Ditch was constructed to accommodate the disposal of nonradioactive, nonsewage liquid discharges. Three landfill units received solid waste similar to that of municipal landfills (construction, petroleum, cafeteria, and small quantities of paint products) from the prototype and support facility operations.

The landfill areas were used intermittently from the time construction started at NRF. In general, construction debris and waste material was burned, then covered with soil. The volume of construction debris decreased after the construction of A1W and ECF in 1958, and after the construction of S5G in 1965. Use of the last NRF landfill ceased by 1971.

In November 1989, the INEL was listed on the National Priorities List (NPL). The DOE, EPA, and State of Idaho Department of Health and Welfare (IDHW) entered into the Federal Facility Agreement and Consent Order (FFA/CO) on December 9, 1991. The entire NRF area will be evaluated in the Waste Area Group (WAG) 8 Comprehensive RI/FS, which is scheduled to begin in 1995.

The RI/FS performed on the IWD evaluated potential risks for both human health and environmental effects. It was found that although there may be some health risk associated with the IWD in the future, the risk is not significant when compared to the background risk, and considering the conservative nature of the estimate.

For the Landfill sites the agencies agreed that the Presumptive Remedy for CERCLA Municipal Landfill Sites was applicable. The assessment of the associated risk presents a large amount of uncertainty due to the volume and heterogeneity of landfill contents make characterization extremely difficult, constituent concentrations in the landfill contents are assumed.
Remedy:  The alternative selected for landfill sites 8-05-01, 8-05-51, and 8-06-53 is the Presumptive Remedy for CERCLA Municipal Landfill Sites. Presumptive remedies are preferred technologies for common categories of sites, based on historical patterns of remedy selection and EPA's scientific and engineering evaluation of performance data on technology implementation. The objective of the presumptive remedies process is to use the EPA's past experience to streamline site investigation and the remedy selection process, thereby improving consistency, reducing cost, and increasing the speed within thick hazardous waste sites are remediated. The specific actions are to survey and mark the areas, restrict land use, monitor soil gases, and install and maintain a two-foot thick native soil cover over the landfill contents by means of administrative controls. Ground water monitoring will be performed to evaluate these and other areas at NRF.
Text:  View full-text ROD [ 116K ]
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