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Tennessee Environmental Procedures Manual

Chapter 3: NEPA Process Options

3.1 Classes of Action

Transportation projects vary in type, size and complexity, and potential to affect the environment. Transportation project effects can vary from very minor to significant impacts on the human and natural environment. To account for the variability of project impacts, three basic "classes of action" are allowed under NEPA and 23 CFR 771.115. The class of action determines how compliance with NEPA is carried out and documented:

  • Class I - Environmental Impact Statement (EIS) is prepared for projects that will cause a significant adverse effect on the environment;
  • Class II - Categorical Exclusion (CE) is prepared for projects that cause minimal social, economic or environmental impact; and
  • Class III - Environmental Assessment (EA) is prepared for larger scale projects that do not meet the requirements for a CE or those for which the significance of the environmental impact is not clearly established. Should environmental analysis and interagency review during the EA process find a project to have no significant impacts on the quality of the environment, a Finding of No Significant Impact (FONSI) is issued. If it is found that the project will have significant impacts, an EIS must be prepared.

Chapter 6, Prepare Environmental Documentation, describes how each of these documents are prepared. FHWA's Technical Advisory, found in Appendix D [pdf 201 kb], provides detailed guidance on preparing and processing environmental and Section 4(f) documents.

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3.1.1 Significance

In essence, the level of analysis and the class of documentation are tied to a project's potential to have "significant" adverse environmental effects. The term "significant, " as used in NEPA, requires consideration of context and intensity, terms that are defined below. Context

The potential significance of an action must be analyzed in several contexts, such as society as a whole (human, national), the affected region, the affected interests, and the locality. Significance varies with the physical setting of the proposed action. For instance, in the case of a site-specific action, significance would usually depend upon the effects in the locale rather than in the world as a whole. In addition, both short- and long-term effects are relevant.

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3.1.2 Intensity

The assessment of significance must also consider the severity or intensity of the impact. Responsible officials must bear in mind that more than one agency may make decisions about partial aspects of a major action. The following should be considered in evaluating intensity:

  • Impacts that may be both beneficial and adverse. A significant effect may exist even if the federal agency believes that, on balance, the effect will be beneficial.
  • The degree to which the proposed action affects public health or safety.
  • Unique characteristics of the geographic area such as proximity to historic or cultural resources, park lands, prime farmlands, wetlands, wild and scenic rivers, or ecologically critical areas.
  • The degree to which the effects on the quality of the human environment are likely to be highly controversial.
  • The degree to which the possible effects on the human environment are highly uncertain or involve unique or unknown risks.
  • The degree to which the action may establish a precedent for future actions with significant effects or represents a decision in principle about a future consideration.
  • Whether the action is related to other actions with individually insignificant but cumulatively significant impacts. Significance exists if it is reasonable to anticipate a cumulatively significant impact on the environment. Significance cannot be avoided by terming an action temporary or by breaking it down into small component parts.
  • The degree to which the action may adversely affect districts, sites, highways, structures, or objects listed in or eligible for listing in the National Register of Historic Places or may cause loss or destruction of significant scientific, cultural, or historical resources.
  • The degree to which the action may adversely affect an endangered or threatened species or its habitat that has been determined to be critical under the Endangered Species Act of 1973.
  • Whether the action threatens a violation of federal, state, or local law or requirements imposed for the protection of the environment.
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