LAUSR

ABSTRACT The U.S. and other developed nations are faced with many contaminated sites remaining from World War II, the Cold War, and abandoned industries, that require remediation and restoration to allow future land uses with minimum acceptable risk to humans and ecological resources. For large Department of Energy (DOE) sites with massive remediation tasks remaining, it is important for managers to be able to assure regulators, Tribal Nations, and the public that human and ecological health are protected. Hanford Site has the largest and most expensive cleanup task within the DOE complex; cleanup will continue beyond 2090. Cleanup involves the use of operating facilities, which also may present a risk to humans or ecological resources. We present a brief description of a methodology to evaluate risks to ecological receptors at the Hanford Site from remaining remediation tasks, and evaluate the risk to ecological resources that operating facilities present currently, during active cleanup of these facilities, and during the post cleanup period. Operating facilities include current, active operations that are located on the site and aid in site cleanup, including both storage and treatment operations. At the Hanford Site, they include waste treatment plants, sludge basins, waste trenches, Central Waste Complex, storage facilities, and disposal facilities, among others. Risk ratings for ecological resources are highest during the remediation phase. Risk ratings for the operating facilities at the Hanford Site range from not discernible to medium currently, from not discernible (ND) to high during active cleanup, and from not discernible to medium following cleanup. The highest ratings are for the Waste Treatment and Immobilization Plant that is being constructed to stabilize radioactive and chemical wastes, and the Liquid Effluent Retention and Treatment Facility that removes and deactivates hazardous contaminants from waste water. Higher ratings in the post‐cleanup period are largely due to restoration of ecological resources during cleanup, which increases the potential for injury (if these resources are harmed) because a site will then have higher quality resources after cleanup than it did before. Assessing the value of ecological resources, and determining potential consequences during active remediation and after remediation is essential for compliance with state and federal laws. Understanding the risks to ecological resources from now until clean‐up is completed at these facilities is important because of the potential for ecological resources of high value to be degraded, and because cleanup completion is not expected until 2090 or later. The methodology can be applied to any contaminated site requiring a rapid method of assessing potential damages to ecological resources from proposed management actions. Graphical abstract Figure. No caption available. HighlightsMany contaminated sites are in need of remediation.During cleanup, humans and the environment must be protected.A method to evaluate risk to ecological resources is presented.Risks are highest during remediation, and lower thereafter.Disruption during cleanup is the major threat to eco‐resources.