Definitions and Acronyms

Environmental Site Assessment (ESA)

A site evaluation or assessment conducted for purposes of determining the extent, if any, of contamination on a property. An assessment can be informal or formal and can consist of several stages. For example, a Phase I ESA, or basic study of possible contamination at a site is limited to collecting information about past and current site use and observing current conditions. A Phase II ESA sometimes follows up on a Phase I ESA, with sampling and analysis of suspected contaminated areas of a site. A Phase III assessment either follows up a Phase II assessment 1) by gathering information on the extent of contamination, or 2) by preparing plans and alternatives for site cleanup.


Real property, either currently in use or vacant, the expansion, redevelopment, or reuse of which may be complicated by the presence or perceived presence of a hazardous substance, pollutant, or contaminant. Cleaning up and reinvesting in these properties protects the environment, reduces blight, and takes development pressures off greenspaces and working lands.

Comprehensive Environmental Response Compensation, and Liability Act (CERCLA or Superfund)

A federal statute that governs the investigation and cleanup of sites contaminated with hazardous substances. The law establishes a trust fund that can be used by the government to clean up sites on the National Priorities List.