Based on analysis of the extensive data compiled for over 30 years, the IWCS, which was engineered and constructed by the U.S. Department of Energy in the mid-1980s, is performing as designed and remains protective of human health and the environment.

During 2015, the Corps of Engineers released a feasibility study and proposed plan for the IWCS OU. The proposed plan identified Alternative 4: excavation, partial treatment, and off-site disposal of the entire contents of the IWCS as the preferred alternative. Responses to comments received on the proposed plan were included in the record of decision. A video of the public meeting, the meeting transcript, and the comments received regarding the proposed plan are available in the Public Presentations/Posters/Transcripts section of this webpage.

During 2019, the Corps of Engineers completed the decision making for the most significant source of contamination at the site, the IWCS, with a record of decision to completely remove the entire IWCS, process the contaminated materials, and ship the materials out of state for permanent disposal. The 2019 record of decision is available in the Reports section below.

During September 2021, the Corps of Engineers awarded a $35M architect-engineer contract to prepare detailed plans and designs and provide construction management services for the complete removal of the IWCS.

The record of decision for the NFSS Balance of Plant and Groundwater OUs is available at the link provided in the Reports section below. A fact sheet regarding the record of decision is available at the link in the Fact Sheet/FAQs section below.

The selected remedy outlined in the record of decision for both OUs is Alternative 2, Complete Removal. The major components of the selected remedy include: removal and off-site disposal of radiological- and/or chemically contaminated soil, road bedding, and Building 401 foundation/utilities; removal and off-site disposal of impacted foundations and underlying soil, including Building 430 and 431/432, and Building 433; and, removal and off-site disposal of a chlorinated volatile organic compound soil and groundwater plume and placement of clay backfill into the excavation. FUSRAP-related material that is removed will be transported off-site for disposal at an appropriately permitted disposal facility.

Based on input received during the public comment period, the Corps of Engineers’ selected remedy for the Balance of Plant and Groundwater OUs was changed from the preferred alternative outlined in the proposed plan, which was Alternative 3, Removal with Building Decontamination. The main differences between the alternatives are the remedial strategies for building foundations (other than Building 401) and the chlorinated volatile organic compound plume. Contaminated concrete will be excavated under Alternative 2 and would have been scarified to remove contamination and left in place under Alternative 3. Clay soil be used to backfill the chlorinated volatile organic compound excavation area to ensure the protectiveness of the remedy.

A contract to remediate the Balance of Plant and Groundwater OUs is currently scheduled for award in 2023. After complete removal of the IWCS, the soils beneath the IWCS will be investigated and remediated, as necessary, using the remediation goals outlined in the record of decision for the Balance of Plant and Groundwater OUs.

Following completion of remedial activities, the site would be suitable for industrial use (i.e., protective of construction, industrial, and maintenance workers, as well as adolescent and adult trespassers). Five-year reviews will be conducted to ensure protectiveness of the remedy.

The administrative record file, which contains the documents supporting the decision-making process for the site, is available electronically at the link below.

During the 1980s the DOE began cleanup and consolidation of the radioactive wastes and residues that were on NFSS and its VPs. The DOE found that VP C and VP H did not require remedial action. Remedial action performed on VPs A, B, C Prime (C’), D, F, H Prime (H’), L, M, N/N Prime (N/N’) North, N/N’ South, P, Q, R, S, T, U, V, W, X, W was completed in 1986. The DOE closed those VPs; certified they were in compliance with DOE decontamination criteria and standards at the time, which were developed to protect human health, safety, and the environment; and released the VPs for unrestricted use.

The Corps of Engineers is responsible for environmental investigations and response at open NFSS VPs. Four parcels, VP-E, E-Prime, H-Prime, and G, are located north of NFSS on a private parcel owned by CWM Chemical Services, LLC. These open VPs were impacted by MED/AEC. Three of these parcels, VP-E, E-Prime, and G were not accessible for investigation by the DOE. The Corps will investigate these VPs once the areas are accessible for investigation and sufficient funding is available. The Corps is currently preparing a remedial investigation report for VP H-Prime, and performing a site inspection of VP X, which is owned by the Town of Lewiston.