Phase I Environmental Site Assessment

A due diligence investigation that evaluates a property's environmental condition by reviewing historical records, conducting site inspections, and interviewing stakeholders to identify recognized environmental conditions.

What is a Phase I Environmental Site Assessment?

A Phase I Environmental Site Assessment (Phase I ESA) is a due diligence investigation conducted to evaluate the environmental condition of a property, typically in connection with a real estate transaction. The assessment identifies recognized environmental conditions (RECs) — the presence or likely presence of hazardous substances or petroleum products on, in, or at the property. Phase I ESAs are conducted in accordance with ASTM E1527 standards.

What a Phase I ESA Includes

The assessment has four main components: a records review (examining historical aerial photographs, fire insurance maps, environmental databases, government records, and prior reports), a site reconnaissance (physical inspection of the property and surrounding area for evidence of contamination), interviews (with current and past owners, operators, and local officials), and a report documenting findings and conclusions. Notably, a Phase I ESA does not involve soil or groundwater sampling.

Why Phase I ESAs Are Important

Phase I ESAs provide the "innocent landowner defense" under CERCLA (the federal Superfund law), protecting purchasers from liability for pre-existing contamination if they conducted appropriate inquiry before acquisition. Lenders universally require Phase I ESAs before financing commercial real estate transactions. Discovering contamination after purchase without the protection of a Phase I can result in significant cleanup liability.

When Further Investigation Is Needed

If a Phase I ESA identifies recognized environmental conditions, a Phase II ESA (involving soil and groundwater sampling) is typically recommended to confirm or rule out actual contamination. Phase II assessments add cost and time but provide essential information for quantifying cleanup liability and negotiating transaction terms.