Date Published: October 2012
A Tier 1 review evaluates and analyzes environmental impacts related to proposed activities that will occur on a typical site (even though the locations are not yet known) within a specified geographic area. Any environmental compliance issues and/or impacts that could not be resolved without knowing the exact project location within the targeted neighborhood are addressed later in the Tier 2 review.
A Phase 1 Environmental Site Assessment (ESA) addresses only one environmental compliance element of a tiered review, environmental assessment, or categorical exclusion review document. It is a report usually undertaken by an environmental engineer that identifies potential or existing environmental contamination liabilities through inquiry into known environmental hazards (according to the ASTM Phase 1 ESA standards). The Phase I ESA however does not include actual collection of physical samples or chemical analyses of any kind, which a Phase 2 Environmental Assessment would include.
A detailed discussion of tiered environmental reviews is available in Chapter 9 of the HOME and Environmental Review Training Manual.