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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/R10-93/070
ROD Date:  09/24/1993
Operable Unit(s):  18
Media:  Soil, Debris
Contaminant:  VOCs, Other Organics, Metals, Radioactive Materials
Abstract:  The USDOE Idaho National Engineering Laboratory (Operable Unit 18) is part of the 890-square mile USDOE facility located in Idaho Falls, Idaho. Operable Unit 18 is part of the Idaho National Engineering Lab and addresses source contamination at the Radioactive Waste Management Complex (RWMC). The primary mission of the Idaho National Engineering Lab (INEL) is nuclear reactor technology development and waste management. Land use in the area is mixed industrial, agricultural, and recreational. Approximately 11,700 people are employed at the INEL, with approximately 100 employed at the RWMC. Drinking water for the employees is obtained from onsite production wells. The site is contained within the northeastern portion of the Eastern Snake River Plain, borders a floodplain to the west and north, and overlies the Snake River Plain Aquifer, a sole-source aquifer. The 144-acre RWMC is located in the southwestern portion of the INEL, and includes two storage areas, the Transuranic Storage Area (TSA) and the Subsurface Disposal Area (SDA). In the early 1950s, the RWMC was established as the disposal site for solid, low-level radioactive waste (LLW) generated by INEL operations. The SDA was used to bury radioactive waste materials in underground pits, trenches, and soil vault rows, and to store waste on one aboveground pad. The TSA was used for interim storage of transuranic waste, and continues to be used for that purpose. From 1952 to 1970, TRU waste, from both the INEL and the USDOE Rocky Flats facility, was disposed of in the SDA. The USDOE Rocky Flats facility was primarily engaged in the production of plutonium components for nuclear weapons. Between 1967 and 1969, drums, boxes, and large items were placed in the 1-acre Pit 9 at the SDA, and a soil cover was applied over the waste. Approximately 110,000 ft[3] of the waste buried in Pit 9 was generated at the Rocky Flats facility and consisted of drums of sludge contaminated with a mixture of TRU elements and organic solvents, drums of assorted waste, and cardboard boxes containing empty contaminated drums. Currently, LLW contaminated with TRU isotopes less than or equal to 100 pCi/g, but greater than 10 pCi/g, is excluded from disposal at the RWMC and is placed in interim storage. LLW contaminated with TRU isotopes less than 10 pCi/g is currently disposed of in the SDA; however, no waste disposal has occurred in Pit 9 at the SDA since its closure in 1969. Since the early 1970s, USDOE has conducted subsurface monitoring at the RWMC to determine if radionuclides, or other hazardous contaminants, have migrated deeper into the subsurface. In 1987, EPA required USDOE to conduct an initial assessment and screening of all solid waste and/or hazardous waste disposal units at the INEL, and set up a process for conducting any necessary corrective actions. In 1990 and 1991, it was discovered that current levels of VOCs in the groundwater below the RWMC were not exceeding SDWA MCLs. This ROD addresses the eighth of thirteen planned remedial actions for this site and specifically addresses source contamination at Pit 9 of the SDA, within the RWMC, as OU18. The primary contaminants of concern affecting the soil and debris are VOCs, including PCE and TCE; other organics, including PCBs; metals, including lead; and radioactive materials. SELECTED REMEDIAL ACTION: The selected interim remedial action for this site includes selecting a suitable subcontractor proposal from those submitted to USDOE in order to determine the exact sequence of treatment process(es) that will be used; excavating the waste, soil, and debris from Pit 9 using a doublecontained structure that will be built over the Pit to contain emissions; physically separating the waste into different waste streams based on whether treatment is required; placing the waste streams into the appropriate onsite treatment processes; using chemical extraction processes to remove contaminants from the waste; stabilizing the waste using a thermal processing unit similar to a plasma heating unit, or using an alternate solidification process; temporarily storing onsite treated residuals with TRU isotopes of equal to or less than 100 pCi/g; returning treated residuals with TRU isotopes of less than 10 pCi/g to Pit 9; monitoring the ground water onsite; and implementing institutional controls, including deed and land use restrictions. The estimated capital cost for this interim remedy is $20,661,000, which includes an estimated total O&M cost of $29,102,000. PERFORMANCE STANDARDS OR GOALS: Soil and debris cleanup goals are based on Federal and State standards. Chemical-specific soil and debris goals for treated waste containing less than or equal to 100 pCi/g, and being returned to Pit 9, are based on maximum allowable leachate concentrations (MALs) for RCRA delisting and health-risk based levels, and include carbon tetrachloride 18 mg/kg; PCE 45 mg/kg; potassium cyanide 119 mg/kg; sodiumcyanide 122 mg/kg; 1,1,1-TCA 2,910 mg/kg; and TCE 15 mg/kg. Chemical- specific soil and debris goals for treated waste residuals containing less than 10 pCi/g and being temporarily stored onsite are based on RCRA LDRs, and include carbon tetrachloride 5.6 mg/kg; lead 5 mg/l; mercury 260 mg/kg; PCE 5.6 mg/kg; potassium cyanide 122 mg/kg; 1,1,1-TCA 5.6 mg/kg; and TCE 5.6 mg/kg. INSTITUTIONAL CONTROLS: Deed and land use restrictions will be implemented to restrict access, maintain the integrity of the soil cover, and ensure protection of human health and the environment.
Remedy:  This ROD addresses the contamination of Pit 9 at the RWMC, Subsurface Disposal Area (SDA), at the Idaho National Engineering Laboratory (INEL). The RWMC has been designated as Waste Area Group (WAG) 7 of the ten WAGs at the INEL that are under investigation pursuant to the Federal Facility Agreement and Consent Order (FFA/CO) between the Idaho Department of Health and Welfare (IDHW), the EPA, and the U.S. Department of Energy Idaho Operations Office (DOE-ID). Pit 9, designated Operable Unit (OU) 7-10, is located within WAG 7. The selected remedy for Pit 9 will use a combination of chemical extraction, physical separation, and/or stabilization technologies to recover contaminants and reduce the source of contamination.

The major components of the remedy are:
. Proof-of-Process (POP) to demonstrate that designated performance objectives and cleanup criteria are attainable;
. Limited Production Test (LPT) to give a high degree of confidence that performance objectives and cleanup criteria can be met and all systems are reliable before full-scale remediation;
. Excavation and segregation of waste with greater than 10 nanocuries per gram (> 10 nCi/g) TRU elements for input into the treatment process;
. Treatment of waste using chemical extraction, physical separation, and/or stabilization to remove radionuclides and hazardous constituents and to reduce the toxicity, mobility, and/or volume of those wastes that remain;
. Treatment of listed hazardous waste to levels which will allow for delisting of the waste (for material being returned to the pit) in accordance with the Resource Conservation and Recovery Act (RCRA) and the Idaho Hazardous Waste Management Act (HWMA);
. Return of treated materials to Pit 9 (treated materials will contain less than or equal to ( ) 10 nCi/g TRU elements and meet regulatory standards for hazardous substances of concern);
. Volume reduction by approximately 90% (for material undergoing treatment); and
. Onsite storage of concentrated waste residuals in accordance with ARARs until final disposal.

Because some aspects of the remedial technologies have not been proven on radioactively contaminated, hazardous waste sites like Pit 9, implementation of the preferred remedial alternative is contingent upon successful demonstration that the cleanup criteria and other performance objectives can be met in the POP and LPT test phases. If processes are not successful in the POP or LPT test phases, then Pit 9 will be reevaluated for remediation at a later date but no later than the TRU-Contaminated Pits and Trenches OU 7-13 Remedial Investigation/Feasibility Study (RI/FS)as identified in Table A-1 of the FFA/CO. Additionally, if the POP results demonstrate the process is not cost-effective, then Pit 9 will be reevaluated by DOE, IDHW, and EPA for remediation.


The selected remedy is protective of human health and the environment, complies with Federal and State applicable or relevant and appropriate requirements (ARARs), and is cost-effective. This remedy uses permanent solutions and alternative treatment technologies to the maximum extent practicable and satisfies the statutory preference for remedieswhich employ treatment that reduces toxicity, mobility, or volume as a principal element. Because this remedy will result in hazardous substances remaining onsite above health-based levels, a review will be conducted within five years after commencement of the remedial action to ensure that the remedy continues to provide adequate protection of human health and the environment. The effectiveness of the Pit 9 interim action remedy as a final action will be further evaluated in the TRU-Contaminated Pits and Trenches OU 7-13 RI/FS which will commence within a five-year period.

Signature sheet for the foregoing Pit 9 located in the Subsurface Disposal Area of the Radioactive Waste Management Complex at the Idaho National Engineering Laboratory Record of Decision between the U.S. Department of Energy and the Environmental Protection Agency, with concurrence by the Idaho Department of Health and Welfare.
Text:  View full-text ROD [ 92K ]
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