Importance of buffer lands to determining risk to ecological resources at legacy contaminated sites: A case study for the Department of Energy’s Hanford Site, Washington, USA

Contaminated lands remain from World War II, the Cold War, and industrial development. The U.S. Department of Energy (DOE) faces the largest cleanup task, with Hanford Site having the biggest challenge. DOE is committed to protection of human health and the environment during remediation. The Hanford Site has extensive ecological resources and unique ecosystems that require protection. The aims of this study were to: 1) describe a rapid evaluation method for ecological resources, 2) examine the relationship between the resource values on evaluation units (EU) and associated buffer lands for legacy waste sites, 3) discuss risk ratings for ecological resources during remediation, and 4) determine why the relationship may differ among different types of waste sites. For legacy sites, the risk rating for ecological resources was largely a function of % of valued resources on EUs and their buffer (in a 1:1 ratio). This ratio differs from that on operating facilities considered previously, where the relationship between high-quality resources was 1:4. The differences are unusual because both types of facilities are located on the Hanford Central Plateau where active waste management occurs. Differences may be due to 1) location of legacy sites close to the edge of waste area, 2) size of legacy site EUs, which indicates that buffers are large and extend into shrub-steppe habitat, and 3) less human activities on legacy sites. Considering risk from cleanup on ecological resources before the planning and during execution of a remediation strategy may reduce damages to ecological resources and remediation costs.