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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/541/R-00/039
ROD Date:  01/21/2000
Operable Unit(s):  11
Abstract:  The Idaho National Engineering and Environmental Laboratory (INEEL) is a U.S. Department of Energy (DOE) facility located in southeastern Idaho, 51.5 km (32 mi.) west of Idaho Falls. The laboratory encompasses approximately 2,305 km2 (890 mi2) of the northeastern portion of the Eastern Snake River Plain and extends across portions of five Idaho counties: Butte, Jefferson, Bonneville, Clark, and Bingham.

The Idaho National Engineering and Environmental Laboratory (INEEL) was established in 1949 as the National Reactor Testing Station by the U.S. Atomic Energy Commission (AEC) for nuclear energy research and related activities. It was re-designated the Idaho National Engineering Laboratory in 1974 and the INEEL in 1997 to reflect the expansion of its mission to include a broader range of engineering and environmental management activities. The INEEL was placed on the National Priorities List in November 1989.

Current land use at the INEEL is primarily for nuclear research, development, and waste management. The perimeter area of the INEEL is leased for cattle and sheep grazing under the management of the U.S. Bureau of Land Management. The perimeter area functions as a controlled safety-and-security buffer between INEEL activities and the general public. No grazing takes place within 0.8 km (0.5 mi.) of any facility boundaries. Controlled hunting is permitted on INEEL land, but is restricted to the 0.8 km (0.5 mi.) strip just inside the site boundary.

State Highways 22, 28, and 33 cross the northeastern portion of the INEEL and U.S. Highways 20 and 26 cross the southern portion. Except for public travel on the highways, access to the INEEL is controlled by fences and security personnel.

The Snake River Plain Aquifer (SRPA), the largest potable aquifer in Idaho, underlies the Eastern Snake River Plain. The aquifer covers an area of approximately 24,853 km2 (9,600 mi2). Approximately 9% of the aquifer's area is below the INEEL. The depth of the aquifer varies from approximately 61 m (200 ft.) below Test Area North (TAN) to approximately 274 m (900 ft.) on the southwest edge of the INEEL.

More than 400 plant species, 190 bird species, and 40 mammal species have been identified on the INEEL. Several bird species at the INEEL warrant attention because of sensitivity to disturbance or their threatened status, including the ferruginous hawk (Buteo regalis), bald eagle (Haliaeetus leucocephalus), long-billed curlew (Numenius americanus), and the loggerhead shrike (Lanius Ludovicianus). In addition, the Townsend's big-eared bat (Plecotus Towndendii) and pygmy rabbit (Brachylagus Idahoensis) are listed by the U.S. Fish and Wildlife Service as candidates for consideration as threatened or endangered species. The ringneck snake (Diadophis punctatus), whose occurrence is considered to be INEEL-wide, is listed by the Idaho Department of Fish and Game as a Category C sensitive species.

The INEEL lies within the lands traditionally occupied by the Shoshone-Bannock Tribes. The tribes used the land and waters within and surrounding the INEEL for fishing, hunting, and plant gathering, in addition to medicinal, religious, ceremonial, and other cultural uses. Under the cooperative Agreement-in-Principle between the Shoshone-Bannock Tribes and the U.S. Department of Energy (DOE 1998) some tribal activities continue today within the INEEL boundaries.
Remedy:  The selected remedy for Wask Area Group (WAG) 5 comprises three remedial actions to mitigate the risk associated with seven specific sites, and limited action to implement institutional controls. Management of stored and investigation-derived waste and groundwater monitoring also are components of the selected remedy. The first remedial action addresses a collection of five individual sites where contaminated soil is the only source medium. The second remedial action will mitigate residual contamination in a sanitary waste system. The only principal threat identified in WAG 5, addressed by the third remedial action, is posed by the contents of an underground storage tank. The limited action addresses institutional controls that will be implemented at nine additional sites and outlines the development of an institutional control plan for WAG 5.

Soil contaminated with concentrations in excess of the remediation goals will be removed using conventional earth-moving equipment (e.g., scrapers and backhoes).

Real-time analyses will be used before and during excavation to delineate the extent of contaminant for removal. Soil sampling and laboratory analysis will be used to verify that remediation goals have been satisfied.

Areas that have been excavated to depths greater than 0.3 m (1 ft) will be backfilled with uncontaminated soil or sloped to promote drainage. All excavations will be contoured to match the surrounding terrain and vegetated.

Contaminated soil will be characterized and sent to the INEEL CERCLA Disposal Facility (ICDF) for another location within the INEEL for permanent disposal.

Institutional controls consisting of signs, access controls, and land-use restrictions will be maintained until remediation is complete. Post-remediation institutional control requirements will be identified based on the results of post-remediation sampling. Institutional controls will not be required after remediation if all contaminated media are removed to basalt or if contaminant concentrations are comparable to local background values. Otherwise, institutional controls will be maintained until discontinued based on the results of a 5-year review.

Five-year reviews will be conducted for remediation sites with institutional controls.

The ARA-02 Sanitary Waste System will be remediated to mitigate excess human health risk. External exposure to radioactive contaminants is the primary exposure of concern. The entire system (i.e., three septic tanks, a seepage pit, and piping) will be removed. However, the unacceptable risk is associated only with contaminants in residual dry sludge at the bottom of the seepage pit. A time-critical removal action was implemented in 1996 to remove the contents of the septic tanks. The remediation of the Sanitary Waste System will include the following activities:

The sludge in the seepage pit will be removed and sent to the INEEL Waste Experimental Reduction Facility (WERF) for batch incineration and final disposition.

The components of the Sanitary Waste System (i.e., the seepage pit gravel and cinder blocks, three septic tanks, and pipes) will be excavated. The debris will be sent to a permitted disposal facility off the INEEL such as Envirocare in Clive, Utah, or an approved facility on the INEEL such as the ICDF for final disposal. The debris will be decontaminated or encapsulated only if necessary to meet waste acceptance criteria for disposal.
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