Strategy for integrated CERCLA/NEPA risk assessments

The US Department of Energy (DOE) has established a policy whereby, for remedial actions, the procedural and documentational requirements of the National Environmental Policy Act (NEPA) are integrated with those of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), as amended. However, the objectives of risk assessment under NEPA and CERCLA differ somewhat. Until its recent application at contaminated sites, NEPA analysis has typically been applied to impacts from taking actions at clean sites (e.g., for construction activities), and a somewhat loosely structured process has historically been used to estimate relative risks for NEPA. Decisions such as cleanup levels were not made on the basis of the risk estimates, and they therefore tended to be conservative and were not discussed in detail. In contrast, risks estimated for Superfund (CERCLA) sites are used to focus the decision-making process for those sites and support national prioritization for cleanup, and the US Environmental Protection Agency (EPA) has developed a detailed framework for preparing baseline health risk assessments for these sites. The purpose of this paper is to discuss issues related to integrating the CERCLA and NEPA approaches into the risk assessments that have been prepared for a DOE remedial action project at the Weldon Spring site near St. Charles, Missouri. These issues are grouped into three basic categories: general assumptions for the impact evaluation, data management, and presentation of the methodology and results. This paper is not intended to represent DOE policy and guidance, nor does it represent the only approach that can be used for integrated risk assessments. It merely discusses the process that was used for the Weldon Spring project, articulating the issues that were encountered and how they were addressed