Difference Between Phase I Environmental Site Assessment vs. Phase II

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A Phase I Environmental Site Assessment (ESA) and a Phase II ESA are key components of environmental due diligence. The purpose of a Phase I ESA and Phase II ESA is to limit liability to the Federal Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) laws and in some cases state laws.

The primary difference between Phase I and Phase II ESAs is in the scopes of work. The Phase I ESA identifies potential sources of contamination (recognized environmental conditions (RECs)) through visual observations, historical use reviews, regulatory records, and interviews. A Phase II ESA includes soil, groundwater, and in some cases soil gas/vapor sampling and laboratory analysis to assess whether or not the RECs have resulted in contaminated soil or groundwater.

What Is a Phase I Environmental Site Assessment?

A Phase I ESA is a historical review of a property to identify RECs. Phase I ESAs are conducted in accordance with the American Standard for Testing and Materials (ASTM E 1527) which also satisfies the Environmental Protection Agency (EPA) All Appropriate Inquiry (AAI) requirement to qualify for environmental liability protection under the CERCLA, also known as the Superfund.

The Phase I ESA involves a review of historical records, a site inspection, interviews with owners, occupants, neighbors and local government officials, and a review of available records from state and federal agencies.

The Phase I ESA assesses the likelihood that property has been contaminated and identifies Recognized Environmental Conditions (RECs), which are potential or known soil and groundwater environmental impacts.

Purpose of a Phase I Environmental Site Assessment

The purpose of a Phase I Environmental Site Assessment is to qualify the purchaser as a bona fide purchaser and provide a defense to CERCLA liability by meeting the EPA All-Appropriate Inquiry (AAI) rule. The assessment applies to new purchasers of property.

The Phase I ESA also includes a determination of the need for further investigation to assess if the property has been contaminated.

Phase I Environmental Site Assessment Cost

The cost to complete a Phase I ESA will vary based on the current land use, the size of the property, review of government records related to known contamination, and historical data.

What Steps Does a Phase I Environmental Site Assessment Involve?

Environmental Inspection of Site

The process of an environmental site inspection includes reviewing the client questionnaire, reviewing the history to determine past use and regulatory records, a site walk and reconnaissance, and interviews with site contacts and local agencies. The assessment concludes with submitting a report to the client. 

Historical Research 

The Phase I ESA involves a review of reasonably accessible historical records, including historical aerial photographs, city directories, Sanborn fire insurance maps, assessing and planning department records, topographical maps, and environmental reports obtained from government environmental agencies.

Permits and Title Information

Obtaining permits and title information are not a part of the consultant obligation in the ASTM Phase I ESA process. The user is responsible to obtaining and providing this information.


Staff interview property owners and neighbors in-person and local government officials when necessary. The process also depends on information received from government agencies through the Freedom of Information Act (FOIA) process.

What Is a Phase II Environmental Site Assessment?

The Phase II ESA, also referred to as a “subsurface investigation,” typically consists of collecting soil and groundwater samples for laboratory analysis to determine if the RECs identified in the Phase I ESA have resulted in environmental impairment of the property.

Phase II ESAs initial soil and groundwater samples are collected at locations where the highest likelihood of releases has likely occurred based on the RECs identified in the Phase I ESA. These samples can be collected by hand using hand-held equipment or by drilling rigs. Once collected, the samples are sent to a laboratory to determine if contamination is present in the soil and groundwater. If impacts are present, additional soil and groundwater samples may be collected to identify the extent of contamination and to evaluate the need for remediation based on the proposed future use.

Purpose of a Phase II Environmental Site Assessment

The purpose of a Phase II Environmental Assessment and report is to determine the presence, or absence of contamination. 

F&V’s geologists and engineers possess expertise in Phase II Environmental Site Assessment project design. Our Phase II ESA projects are conducted in accordance with the ASTM E1903 Standard Guide for Environmental Site Assessments: Phase II Environmental Site Assessment Process.

Phase II Environmental Site Assessment Cost

Phase II ESA costs vary and are determined by the number of borings and samples and the lab analyses needed to address the RECs.

What Steps Does a Phase II Environmental Site Assessment Involve?

Geophysical Surveys

Geophysical surveys typically consist of ground penetrating radar (GPR) surveys. A GPR survey is used to identify buried objects such as underground storage tanks, former excavation areas, and utilities without disturbing the ground surface. 

Soil Boring

Soil borings are used to collect soil samples and set temporary wells in order to collect groundwater samples. Depending on the depth needed to assess the RECs drilling can be conducted using a hand-auger, a direct push drill rig, or a rig that uses auger to reach greater depths.

Laboratory Analysis 

Soil and groundwater samples are sent to a 3rd party laboratory for analysis of various chemicals based on the suspected contaminants identified in the RECs.

Our Environmental Site Assessment Services

Phase I and II Environmental Site Assessments in Michigan and Indiana are completed by F&V experienced staff with decades of experience.

We have the available staff and experience to complete multi-site portfolios with very short due dates. Contact us today!