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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/R10-92/046
ROD Date:  09/30/1992
Operable Unit(s):  22
Media:  Sediment, Sludge, Debris
Contaminant:  Metals, Radioactive Materials
Abstract:  SITE HISTORY/DESCRIPTION: The 890-square-mile U.S. DOE Idaho National Engineering Laboratory (INEL), located 32 miles west of Idaho Falls, Idaho, is operated by the U.S. Department of Energy. Land use in the area is predominantly industrial and mixed use. The site overlies a sole source Class I aquifer, known as the Snake River Plain Aquifer. Within INEL, an area known as the Power Burst Facility (PBF) operated from 1972 to 1985 and supported the testing of pressurized-water fuel rods under hypothetical reactor accidents. This area contained several site features, including a corrosive waste sump, an evaporation pond, and discharge pipe. From 1978 to 1984, water containing a chromium-based algal and corrosion inhibitor from the PBF reactor's secondary coolant system was discharged from the corrosive waste sump (CWS) via a discharge pipe to an evaporation pond. To prevent discharge of toxic hexavalent chromium to the sump, cooling water was treated in the discharge pipe by bubbling sulfur dioxide through it to reduce the hexavalent chromium to less toxic trivalent chromium, and the treated water was discharged to the sump and neutralized using sodium hydroxide or sulfuric acid. As a result of these activities, approximately 363 cubic yards of sediment in the evaporation pond have been contaminated by metals and radioactive materials. In 1987, the pond and sump were listed as RCRA land disposal units; however, wastewater exhibiting the toxicity characteristic (TC) for chromium is believed to have been discharged after the effective date of the TC rule. The INEL site is currently divided into 10 Waste Area Groups (WAGs). Three previous RODs signed in 1991 and 1992 addressed interim remedies for the warm waste pond sediment in WAG 2, unexploded ordnance and contaminated soil in WAG 10, and ground water contamination from the TS-05 injection well in WAG 1, respectively. This ROD provides an interim remedy for the contaminated sediment and sludge in the evaporation pond, discharge pipe, and waste sump as OU22 in WAG 5. A future ROD will address the underlying aquifer and unsaturated zone. The primary contaminants of concern affecting the sediment, debris, and sludge are metals, including chromium; and radioactive materials. PERFORMANCE STANDARDS OR GOALS: Sediment and sludge excavation goals are based on a site-specific residential use scenario for a populationthat begins residence at the site within 100 years in the future. Chemical- specific goals include chromium 800 mg/kg and cesium-137 30 Pci/g. INSTITUTIONAL CONTROLS: Not applicable.
Remedy:  SELECTED REMEDIAL ACTION: The selected interim remedial action for this site includes removing and solidifying/stabilizing the 100 cubic yards of contaminated sediment from the evaporation pond by grouting, followed by onsite disposal in the Radioactive Waste Management Complex (RWMC) at INEL along with existing lowlevel waste containers; removing sludge and sediment from the waste sump; treating the sludge by grouting, if feasible, based on the results of treatability studies, and disposing of the treated sludge onsite in RWMC; decontaminatingthe discharge pipe; and sampling the remaining sediment to verify residual contaminant concentrations. The estimated total cost for this remedial action is $480,000. No O&M costs were provided for this remedial action.
Text:  View full-text ROD [ 45K ]
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