Phase I or Phase One
Environmental Site Assessment?

A Phase I or Phase One ESA is a non-intrusive preliminary study entailing site history and inspection and documentary research.

In Ontario Phase 1 ESAs are generally conducted in accordance with one of two protocols, notably the Canadian Standards Association (CSA Z-768/01 guidelines) for Phase I ESAs, and Ontario Regulation 153/04 (O.Reg.) for a Phase One ESA, depending on the purpose.


Phase I ESA:
CSA Standard

CSA Z-768/01

Due-Diligence
Pre-Purchase Condition
Financing or Refinancing
Property Purchase/Sale
Property Insurance Condition

Phase I Project Scope

100 m Study Area from Centre of Site Minimum

  • Aerial Imagery
  • Fire Insurance Plans
  • City Directories
  • Title Search
  • OPTA Information Intelligence Records
  • Data Evaluation

Phase One ESA:
O.Reg Standard

O.Reg. 153/04

Record of Site Condition
(RSC) required for change to more sensitive land use

Town/City Planning Departments
(for re-zoning, site plan control and/or building permit)

Phase One Project Scope

Minimum 250 m Study Area from Site Perimeters

  • Aerial Imagery
  • Fire Insurance Plans
  • City Directories
  • Chain(s) of Title
  • First Developed Use
  • Interview with knowledgeable persons
  • OPTA Information Intelligence Records
  • Data Evaluation

Following successful completion of a Phase One ESA and Phase Two ESA (if required), a Record of Site Condition (RSC) can be filed with the Ministry of the Environment & Climate Change (MOECC) for inclusion into the Environmental Bill of Rights Registry.


Phase I ESA
Phase One ESA
Phase 1 ESA
Phase I Environmental Site Assessment
Phase I or Phase One Environmental Site Assessment