What is a tiered NEPA process?
Tiering is a procedure for completing the National Environmental Policy Act (NEPA) process in two separate stages, known as tiers. The first tier involves the preparation of an Environmental Impact Statement (EIS) that examines a large land area or a broad set of issues associated with a major federal action that triggers the NEPA process. The second tier generally involves the preparation of several, separate NEPA documents, which could include EISs; Environmental Assessments (EAs); or even Categorical Exclusions (Cat Exs) for specific projects within the overall corridor. For a more detailed understanding of the NEPA process, please review CDOT’s “Environmental Stewardship Guide.
