Illustration of Water and Air Pollution

What is a Phase I environmental site assessment?

A phase 1 environmental site assessment is sometimes referred to as a Phase 1 or Phase 1 ESA. A Phase 1 ESA is a report that summarizes a site visit and it records a review of a property and the surrounding area to find out if ay additional environmental investigation is needed to understand the liability risks that are associated with the identified property.

The main purpose behind a Phase 1 Environmental Site assessment is to use a consistent systematic approach to identifying any existing or potential environmental conditions that may be present or effect a real estate property.

The process of completing a Phase 1 ESA has four components:

Records Review

Chain of title review. What was the property used for in the past? Do any of the uses raise a red flag?

Determine Surrounding land use. This part is very important because the risk of contamination is greater if the surrounding properties have documented contamination.

Historical aerial photograph review. A report will always include historical aerial photos to review a time line for development of the property and surrounding properties.

Agency contacts and related records search. Agencies like fire departments, local health departments, petroleum tank management association, water departments etc. They are contacted so they can gather current and historical important information concerning the property and neighboring area.

Site Reconnaissance

A visual inspection of the property and any improvements play an important role in a Phase 1 ESA.

The building is inspected and property boundary measurement are checked. The focus of a Phase 1 inspection is environmental and does not include the structure or any of the systems of the building.

Pictures of the property re taken.

There is no testing or sampling conducted during a Phase 1 assessment.


Interviews with anyone who has important information that would help the report like past or present property managers or tenants. 

If there is concern over surrounding properties interviews may be conducted with any person that is involved with that property.


Documentation. Findings opinions and conclusions need to be supported by documentation to facilitate the assessment.

Scope of Services. The report must describe all services that are performed in detail to allow another party to construct the work that was completed during the investigation.

Findings. The finding section identifies the known or suspected environmental conditions.

Opinion. Includes the opinion of the environmental professional.

Additional Investigations. The professional should note if any additional in investigations are necessary.

Data Gaps. Comments are needed if there are any data gaps that effect the ability to inspect the property.

Conclusions. Provides a summary of all recognized environmental conditions associated with the property.