Oversight Technical Support for Oak RIdge Remedial ALternative

Tennessee Department of Environment and Conservation (TDEC)

Aerial view of Oak Ridge Reservation

Neptune provides TDEC’s Division of Remediation with independent, third-party, technical support in the evaluation of the U.S. Department of Energy (DOE) Oak Ridge Office of Environmental Management’s (OREM) proposed on-site mixed waste disposal facility, selected as a preferred remedial alternative for cleanup activities at the Oak Ridge Reservation, Oak Ridge, Tennessee.

Neptune is working with TDEC to ensure that DOE meets its obligations and responsibilities under 1) DOE Order (O) 435.1, Radioactive Waste Management; 2) DOE Manual (M) 435.1-1; 3) DOE O 458.1 Radiation Protection of the Public and the Environment; and 4) DOE Standard, Disposal Authorization Statement and Tank Closure Documentation, DOE-STD-5002-2017 through the development of a Performance Assessment (PA) and Composite Analysis (CA) for the proposed facility. Neptune is also working with TDEC to ensure that DOE addresses hazardous (non-radiological) wastes in accordance with CERCLA and Tennessee statutes in a manner that ensures protectiveness of health and the environment.

Neptune’s support for TDEC includes a review of the entire PA and CA, an evaluation of the scenarios selected for modeling, and an evaluation of the overarching modeling approach. Examples of Neptune’s review include:

  • Hydrological modeling of cover performance in HELP

  • Assumptions for long-term degradation of that performance

  • Unsaturated and saturated zone groundwater transport modeling using STOMP and MT3D, including selection of Kd values used in the modeling

  • Waste inventory assumptions and the relationship of these assumptions to existing knowledge about potential waste streams

  • RESRAD model inputs and assumptions

  • Biological impacts on the cover system

  • Erosion modeling in RUSLE2

Neptune has also: 1) conducted supplemental contaminant fate and transport modeling to assess key assumptions of the PA and CA; 2) evaluated acceptable water quality standards corresponding to non-radiological toxicity levels of uranium; and 3) evaluated DOE remedial alternative cost estimates developed for the Remedial Investigation/Feasibility Study (RI/FS). Neptune is also supporting TDEC in its evaluation of DOE’s Waste Acceptance Criteria (WAC) development for the proposed facility and mercury disposal strategy.