At a time when Quebec is seeking to balance economic development, the revitalization of brownfields and other contaminated sites, and environmental protection, it is time to give toxicological risk assessment (human health, flora, and fauna) the priority it deserves.
In the context of contaminated site remediation, the risk-based approach offers an alternative to the conventional method of removing all soil that exceeds applicable regulatory thresholds (based on the site’s intended use), regardless of its depth, location (e.g., beneath a building), or nature.
Used throughout Canada and around the world, risk analysis is a scientific approach that assesses the risks posed by soil contamination based on the site’s characteristics, its current and future use, and its surrounding areas. This rigorous decision-making tool helps identify the remediation work (excavation/treatment) that is actually required and, where appropriate, proposes mitigation and management measures (e.g., containment, use restrictions) that will allow contaminants to remain in place while ensuring their safety in the short and long term.
In Quebec, the risk-based remediation approach is recognized and regulated. It allows for the retention of contaminated soil on a site even if it exceeds the threshold values applicable to its intended use. However, in practice, its application remains very limited due to restrictions on applicability (e.g., types of sites and contaminants), imposed management requirements, and the time required to obtain the necessary ministerial approvals (typically 12 to 18 months).
This article focuses on one of the management requirements imposed by this approach: the obligation to install a surface cover consisting of so-called “clean” soil during site remediation, even if the existing soil poses no toxicological risk. Clean soil refers to materials with contaminant concentrations that meet Criteria A of the Remediation Guide (≤ Criteria A). These criteria correspond either to environmental background levels (e.g., for metals) or to analytical detection limits (for organic substances).
Why require the installation of clean soil?
The guidelines and manuals developed by the MELCCFP clearly state that the installation and long-term maintenance of a containment layer over contaminated soil is an effective mitigation measure for preventing exposure of ecological and human receptors. Without exposure, there is no risk. However, the requirement that this containment layer consist of clean soil (≤ Criteria A) is not clearly justified.
Why should clean soil (≤ Criteria A) be systematically placed on the surface when sites are remediated using a risk-based approach, whereas the conventional remediation approach allows for higher concentrations?
For contaminants currently eligible for the risk-based approach in Quebec (i.e., substances that are minimally mobile or immobile in the environment), installing a containment layer of sufficient thickness prevents contact between the contaminants retained on-site and receptors (humans, wildlife, and vegetation). From the perspective of receptor protection, it is therefore not justifiable to require (for sites remediated using the risk-based approach) a higher quality of surface fill than would otherwise be required.
The requirement to place clean soil (≤ Criteria A) on the surface of any site managed through risk analysis is inconsistent since, according to the conventional approach, no remediation is required and no use restrictions apply when soils comply with regulatory limit values (e.g., slightly contaminated soils, known as “A-B” soils). This requirement can lead to implausible situations. For example, during remediation based on risk analysis, slightly contaminated soils (“A-B”) excavated from a site intended for commercial or industrial use could not be reused on the surface of that same site. However, a ministerial authorization could be obtained (under certain conditions) to reuse this same soil as backfill material on another site remediated using the conventional approach and intended for residential use. This property would not be subject to any use restrictions (e.g., nothing would prevent future owners from establishing a vegetable garden in this soil).
Evolving Quebec’s Regulatory Framework
Risk assessment is a rigorous tool that enables the transparent determination, for any type of contaminant, of concentrations that can be safely left in soil.
The systematic requirement to install a surface cover made of clean soil carries a significant environmental cost. On one hand, obtaining clean soil (consisting of topsoil, sand, etc.) contributes to the destruction of natural habitats. On the other hand, by limiting options for soil remediation, this requirement leads to an increase in the volume of material transported to disposal sites. When a risk can be effectively managed on-site, why require the transport of soil over tens or even hundreds of kilometres? The excavation and importation of thousands of metric tons of material result in hundreds of truck trips, greenhouse gas emissions, noise, dust, accident risks, and damage to road infrastructure. In some situations, excavation does not reduce environmental risk; it simply transfers the liability from one location to another.
Wider use of the risk analysis approach would accelerate the redevelopment of brownfields, reduce remediation costs, and encourage investment, while ensuring that all contaminants left in place are safe. This would allow resources to be focused on areas and sites that truly pose a risk to human health and/or the environment.
SANEXEN has chosen to take action by restructuring its Specialized Consulting Services, with risk analysis as a key focus. Drawing on several decades of expertise, the company assists organizations in developing strategies that comply with provincial and federal frameworks, thereby limiting unnecessary soil excavation and transport, reducing GHG emissions, and making projects possible that would otherwise be delayed or abandoned.
Through its Specialized Consulting Services, SANEXEN is helping organizations take a more sustainable and risk-based approach to contaminated site management. Leveraging decades of expertise in risk analysis, the company develops solutions that align with provincial and federal regulatory requirements, minimize unnecessary soil excavation and transport, reduce greenhouse gas emissions, and enable projects that might otherwise be delayed or rendered unfeasible.
In light of the upcoming provincial elections, we urge political parties to modernize Quebec’s contaminated land management framework by drawing on science and the experience gained here and elsewhere in Canada.
Toxicological risk analysis is not a trade-off between the economy and the environment. It is a decision-making tool that protects people and ecosystems while avoiding interventions whose impacts sometimes outweigh the benefits.
It is time for Quebec to place its trust in the expertise, science, and innovation already within its reach.
