Are All Phase I ESAs Equal?

When O.Reg. 153/04 was updated in 2011, the Ministry of the Environment, Parks and Conservation (MECP) changed from general guidelines for Phase I ESAs to carefully prescribed rules. While the principal components are the same the Regulation now gives a detailed description of steps required including objectives and requirements for each component. These rules are meant to standardize a Phase I report and improve quality for a RSC submission and filing.

The result of these rule changes however is that in certain circumstances (most notably for environmental due diligence during real estate transfers) there is not enough time to complete all the steps required for an O.Reg.153/04 compliant Phase I ESA. In those instances a decision must be made on how to proceed with the environmental site assessment so as not to compromise the objectives of the project.

The Canadian Standards Association (CSA) developed a set of standards for Phase I ESAs in Nov. 2001 with the latest edition reaffirmed in 2016. When O.Reg. 153/04 was updated in 2011 any cross-references to the CSA Phase I ESA requirements were replaced with detailed stand-alone rules, making an O.Reg.153/04 Phase I document standardized.

A Phase I ESA is required to be O.Reg. 153/04 compliant is when an RSC is submitted to the MECP in support of a change of property to a more sensitive land use. Other interested parties including owners, lenders, insurers, or municipalities can determine their required compliance to O.Reg. 153/04 at their discretion. We have seen that many municipalities now require RSCs for zoning or devleopment purposes as well, even when an RSC would not be required under O.Reg. 153/04

In many cases (e.g. real estate transaction, financing, etc.) a CSA compliant Phase I ESA is adequate. As an O.Reg.153/04 compliant Phase I ESA generally has more stringent requirements and thus higher costs associated with it, it is essential that the Phase I ESA requirements be clearly defined by the party requiring the ESA.

The general components of a Phase I ESA are the same for Reg 153/04 and CSA, and include: records review, interviews, site reconnaissance, and evaluation of information and reporting. Specific details of components are not always defined under the CSA standard as it applies across Canada while O.Reg. 153/04 applies only to Ontario.

Some of the differences between an O.Reg.153/04 and CSA Phase I ESA are listed below (not a comprehensive list, but highlights some differences):

O. Reg. 153/04 Phase I ESA


Qualified Person: The person conducting or supervising the Phase I must be a QP as defined under the Reg.

Competence of the Assessor: Not strictly defined, but must be competent to complete a Phase I ESA.

Phase I ESA Study Area: Minimum of 250 m from the nearest point on a boundary of the Phase I property

Phase I ESA Study Area: Minimum of adjacent neighbouring properties

Chain of Title: Back to first developed use

Chain of Title: Required, but no specifics

Environmental Source Information: all reasonable inquiries must be made to obtain national pollutant release inventory (NPRI) information, PCB information, retail fuel storage information,  identification of area of natural significance (ANSIs), MECP records including inventory of coal gasification plants, Environmental Compliance Approvals (ECAs), environmental incidents, waste management records, landfill information

Environmental Source Information: regulatory information including (generally) permits, violations, work orders, prosecutions

Physical Setting Sources: aerial photos dating back to first developed use, topographic maps, physiographic maps, geological maps, and wells records

Physical Setting Sources: aerial photographs

Review and evaluation of information: A Qualified Person is required to prepare an  APEC table, current and past uses table, and  conceptual site model (CSM), in addition to the required report sections

Review and evaluation of information: No specific documents, outside of the written report, are required.

Resource Hub Headers 13
Previous post
What Happens During a Soil Vapour Study ?
Next post
Topographic Site Surveys – Traditional, Modern and Beyond!