Phase I Environmental Site Assessment Changes For Ontario?

You are probably aware of some of the environmental regulatory changes in Ontario (see our message on June 8, 2010, regarding O.Reg 511).  In addition to some of the cleanup standards changing, some changes relate to Phase I Environmental Site Assessments (ESA).  One specific change relates to the search distance from the subject property. Government records and visual inspections are required to be at least 250 metres from the property line (rather than just neighbouring properties).  There are other rather “prescriptive” changes that seem obvious, such as you actually have to go to the site, which begs the question, how were they previously conducting the site inspection?

The Phase I ESA provides the technical foundation for the conduct of additional investigation if required. To illustrate how a seemingly simple Phase I ESA can lead to costly mistakes, here are some of the best of the worst we have observed in conducting ESA peer reviews.

  • Fire insurance maps were reviewed for the wrong site.  This resulted in groundwater remediation being suggested (and implemented) when the client was not the responsible party for the contamination.
  • Soil borings were installed to assess the impact of underground storage tanks that were mistakenly identified on the subject site but were in reality two kilometres away.
  • On one project, someone provided a “clean” Phase II ESA, but when we conducted a peer review and subsequent subsurface investigation, we found not just contamination, but free product. 

Some of the regulatory changes will help in property transactions/investigations by re-enforcing better parameters for ESA investigations to avoid these types of oversights, but prescriptive measures will not likely be effective in changing bad work habits. 

If you have questions about how changes in the environmental regulations may affect your site investigations or if you require assistance with an environmental issue, please contact Clifford Lawton ( or Christopher Paré, P.Geo. ( at 519.979.7300