An old garage, a buried tank, fill of unknown origin: a property can keep the traces of its past uses. An environmental site assessment (also called an environmental characterization) establishes whether the soil or the groundwater is contaminated. It proceeds in phases: each one is undertaken only if the previous one justifies it.
Phase I: the history of the site
Phase I looks for activities that pose a risk, past and present, on the property and around it. It generally follows the CSA Z768-01 standard and involves no sampling. The assessor:
- reviews the records: land titles, aerial photographs, maps, public registers and environmental files;
- visits the site and its surroundings;
- interviews people who know the property;
- concludes whether contamination is possible and whether a Phase II is recommended.
If nothing points to a risk, the assessment stops there.
Phase II: confirming contamination
Phase II checks on the ground what Phase I suspected. It generally follows the CAN/CSA-Z769-00 standard; when the law requires the study, it must comply with the site characterization guide of the Ministère de l’Environnement (MELCCFP), the Guide de caractérisation des terrains. It includes:
- a sampling plan targeting the areas at risk;
- boreholes, test pits and, if needed, observation wells for the groundwater;
- chemical analysis of the samples by an accredited laboratory;
- a report that confirms the presence or absence of contamination, by comparing the results with the applicable criteria.
Phase III: delineating the contamination
When Phase II confirms contamination, an additional characterization, which the ministry’s guide calls Phase III, defines its extent: where it is, at what depth and in what volumes of soil. These data are used to choose the remediation method and to estimate its cost.
What about Phase IV?
The ministry’s guide describes three phases. At Groupe LAFI, Phase IV refers to the remediation of the site: monitoring of the decontamination work, verification analyses and the final report confirming that the site meets the target criteria.
When is an environmental site assessment needed?
- When buying or financing a property. Most financial institutions require an environmental site assessment for a commercial property. The ministry’s guide also mentions that a Phase I may be required by a financial institution.
- When an industrial or commercial activity ends. For the categories of activities designated by regulation, the Environment Quality Act requires anyone who permanently ceases the activity to send a characterization study to the Minister and to the owner of the land within 12 months (section 31.51).
- Before changing the use of land where such an activity was carried out, for example to build housing on it (section 31.53).
- Before building on or redeveloping a property whose history is unknown, or to obtain a permit or an environmental authorization.
Who can sign the study?
Since April 12, 2023, the Act no longer refers to an “expert habilité” (authorized expert). The characterization study must be signed by a professional within the meaning of section 31.42, for example a member of a professional order or a person certified in land characterization and rehabilitation by a body accredited under the ISO/IEC 17024 standard. It must also comply with the Minister’s characterization guide (section 31.67).
How long it takes and how much it costs
The cost and the duration depend on the size of the property, its history, the number of test holes and analyses, and the laboratory’s turnaround time. A Phase I, with no sampling, is faster and less expensive than a Phase II.
For example, our environmental site assessment of a sand pit in the MRC de Manicouagan, with boreholes and an assessment of soil and water quality, took place from October 25 to November 19, 2025.
Every project has its own particularities: see our page on environmental site assessment or request a quote.
Sources
- CSA Group, CSA Z768-01 (R2022), Phase I environmental site assessment: csagroup.org.
- CSA Group, CAN/CSA-Z769-00 (R2023), Phase II environmental site assessment: csagroup.org.
- Ministère de l’Environnement (MELCCFP), Guide de caractérisation des terrains (in French), 2024 edition: environnement.gouv.qc.ca.
- Environment Quality Act, CQLR, c. Q-2, sections 31.42, 31.51, 31.53, 31.65 (repealed) and 31.67: legisquebec.gouv.qc.ca.
- BDC, “What you need to know about environmental site assessments”: bdc.ca.