Glossary
Phase I ESA
Also: Phase I Environmental Site Assessment
A review of a property's history and current conditions to identify potential environmental contamination, following ASTM E1527. The first step in environmental due diligence.
A Phase I Environmental Site Assessment is a records-and-reconnaissance study of a property meant to identify recognized environmental conditions — signs of likely contamination — without collecting samples. It reviews historical use, regulatory databases, and a site walkthrough.
The work follows the ASTM E1527 standard, which underpins the “all appropriate inquiries” a buyer performs to qualify for certain liability protections under federal law. If the Phase I flags a concern, a Phase II ESA follows with actual sampling.
On a brownfield or any older industrial property, the Phase I is typically where an asbestos, lead, or contaminated-materials scope first gets identified.