Streamlined Approach for Environmental Restoration (SAFER) Plan for Corrective Action Unit 465: Hydronuclear Nevada National Security Site, Nevada, with ROTC 1, Revision 0

This Streamlined Approach for Environmental Restoration (SAFER) Plan addresses the actions needed to achieve closure for Corrective Action Unit (CAU) 465, Hydronuclear, identified in the Federal Facility Agreement and Consent Order (FFACO). Corrective Action Unit 465 comprises the following four corrective action sites (CASs) located in Areas 6 and 27 of the Nevada National Security Site: (1) 00-23-01, Hydronuclear Experiment; (2) 00-23-02, Hydronuclear Experiment; (3) 00-23-03, Hydronuclear Experiment; (4) 06-99-01, Hydronuclear. The sites will be investigated based on the data quality objectives (DQOs) developed on July 6, 2011, by representatives of the Nevada Division of Environmental Protection (NDEP) and the U.S. Department of Energy (DOE), National Nuclear Security Administration Nevada Site Office. The DQO process was used to identify and define the type, amount, and quality of data needed to determine and implement appropriate corrective actions for each CAS in CAU 465. For CAU 465, two potential release components have been identified. The subsurface release component includes potential releases of radiological and nonradiological contaminants from the subsurface hydronuclear experiments and disposal boreholes. The surface release component consists of other potential releases of radiological and nonradiological contaminants to surface soils that may have occurred during the pre- and post-test activities. This plan provides the methodology for collection of the necessary information for closing each CAS component. There is sufficient information and process knowledge from historical documentation, contaminant characteristics, existing regional and site groundwater models, and investigations of similar sites regarding the expected nature and extent of potential contaminants to recommend closure of CAU 465 using the SAFER process. For potential subsurface releases, flow and transport models will be developed to integrate existing data into a conservative description of contaminant migration in the unsaturated zone from the hydronuclear experiments and disposal boreholes. For the potential surface releases, additional information will be obtained by conducting a field investigation before selecting the appropriate corrective action for each CAS component. It is anticipated that results of the flow and transport models, the field investigation, and implementation of the corrective action of closure in place will support a defensible recommendation that no further corrective action is necessary. This will be presented in a closure report that will be prepared and submitted to NDEP for review and approval. The following text summarizes the SAFER activities that will support the closure of CAU 465: (1) Perform site preparation activities (e.g., utilities clearances, and radiological and visual surveys). (2) Move or remove and dispose of debris at various CASs, as required. (3) Collect environmental samples from designated target populations (e.g., stained soil) to confirm or disprove the presence of contaminants of concern as necessary to supplement existing information. (4) Evaluate and analyze existing data to develop conservative flow and transport models to simulate the potential for contaminant migration from the hydronuclear experiments and disposal boreholes to the water table within 1,000 years. (5) Confirm the preferred closure option (closure in place with use restrictions) is sufficient to protect human health and the environment