Phase I Environmental Site Assessment

Environmental Site Assessments: What You Need to Know Before Purchasing a Property

Written by Dawn Gough, MTech


Environmental site assessment, Phase I ESA, property transaction, due diligence, environmental liability, contaminated property, Canadian Standards Association.


This article discusses the importance of environmental site assessments (ESAs) in property transactions, particularly Phase I ESA, which provides a non-intrusive look at the entire property and its neighboring land to identify current and potential site contamination through a collection of data sources. We will explain the legalities behind ESAs, which are required by some lenders and insurance companies, and the Canadian Standards Association (CSA) framework that provides a consistent framework for environmental professionals. We will summarize what a Phase I ESA entails, which includes reviewing all documents provided by the client and public records search, conducting a site visitation and visual inspection, interviews, and evaluation of gathered information and reporting. The article concludes with information on how to initiate a Phase I ESA.


Environmental site assessments (ESAs) are crucial in property transactions to identify current and potential site contamination, helping to manage environmental liabilities. In this article, we will discuss what a Phase I ESA is, why ESAs are required, the Canadian Standards Association framework, and the components of a Phase I ESA.

What is a Phase I Environmental Site Assessment (ESA)?

A Phase I ESA is a comprehensive assessment conducted by an environmental professional to identify potential environmental liabilities associated with a property. This assessment includes a review of historical records, interviews with site owners, and a site inspection to identify current and potential site contamination.

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Why are ESAs Required?

ESAs are required to ensure that environmental factors are considered throughout the initial planning stages of a project. They help manage environmental liabilities, fulfill government requirements, and perform due diligence in the protection of human health and the environment. Some lenders and insurance companies may also require a Phase I ESA as a condition to financing.

What is the CSA Framework?

The Canadian Standards Association (CSA) Standard Z768 provides a consistent framework that environmental professionals use to provide their clients with an organized, clear, and concise scenario. By offering simplified, logical, and systematic procedures, the assessor can focus on providing pertinent information that will help the client decide whether to purchase the property, proceed with further testing, or enact a site remediation project.

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Components of a Phase I ESA

A Phase I ESA typically includes four components:

  1. The evaluation and reporting of existing information collected through a records review,
  2. An on-site visitation and visual inspection,
  3. Interviews with relevant parties, and
  4. An evaluation of gathered information and reporting.

The first step in a Phase I ESA is reviewing all available documents provided by the client and conducting a public records search. This provides a thorough understanding of the site history and helps identify potential sources of contamination.

The site visit is then conducted to target specific areas of the property for further investigation. This includes identifying any hazardous materials or waste, taking note of the relative quantities, types of containers, and storage conditions. The exterior and interior of any buildings on the property are also inspected.

Next, interviews are conducted with individuals knowledgeable about the site operations, including the site owner, neighbours, and regulatory agencies. This information is used to back up the findings and provide thoughtful considerations for the client.

Finally, the results of the ESA are provided in an easy-to-read format, including an appendix with all of the findings for future reference.

Initiating a Phase I ESA

To initiate a Phase I ESA, the client should provide as much information as possible, including the reason for requesting the assessment (property transaction, commercial development, lender requirement, government requirement), and any relevant documentation. This helps the environmental consultant understand the scope of work and provide an accurate quote.


Navigating the complex environmental legislation in Canada can be challenging without the involvement of an experienced environmental professional. A Phase I ESA is a valuable tool for individuals and businesses to make informed decisions when purchasing a property. ESAs are required by lenders and insurance companies to identify potential environmental liabilities and manage environmental risks. The Canadian Standards Association framework provides a consistent approach for environmental professionals to provide clear and concise information to clients. To initiate a Phase I ESA, contact an environmental consultant with the necessary experience and expertise.


If you are interested in booking an appointment for a Phase I ESA, please email or visit our contact page.

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