Recent changes to Protocol 22 under British Columbia’s Contaminated Sites Regulation (CSR) will affect how environmental consultants evaluate vapour intrusion risks at contaminated sites across the province. For property owners, developers, lenders, and municipalities, understanding these updates is important when pursuing regulatory approvals or assessing environmental liabilities.
The revised Protocol 22, Application of Vapour Attenuation Factors to Characterize Vapour Contamination, will come into effect on January 15, 2027.
What is Protocol 22?
Protocol 22 provides guidance for estimating indoor and outdoor air concentrations based on contaminants detected in soil vapour, groundwater, and subsurface soils. The protocol is a key component of vapour intrusion assessments completed under BC’s Contaminated Sites Regulation.
Environmental consultants use Protocol 22 when evaluating whether volatile contaminants such as petroleum hydrocarbons, chlorinated solvents, or other volatile organic compounds (VOC) may pose risks to human health. The results often support regulatory submissions, Approval in Principle (AiP) applications, risk assessments, and Certificates of Compliance (CofCs).
Key Changes to Protocol 22
1. Removal of the Parkade Attenuation Adjustment Divisor
- One of the most notable changes is the elimination of the Parkade Attenuation Adjustment Divisor (PAAD). The Ministry has replaced this approach with a vapour attenuation factor (VAF), creating a more consistent methodology for estimating vapour concentrations in buildings and parkades.
- For environmental consultants conducting vapour intrusion assessments, this change simplifies the framework and improves consistency between exposure scenarios.
2. Updated Biodegradation Factors
- The revised protocol introduces updated Biodegradation Attenuation Adjustment Divisors (BAADs) and revised sub-slab vapour attenuation factors.
- These updates reflect current scientific understanding of how petroleum hydrocarbon vapours degrade in the subsurface before reaching occupied buildings. For some contaminated sites, the changes help provide additional relief for calculated vapour risks and could affect remediation strategies or site investigation requirements.
3. Urban Parks Reclassified
- Urban parks are now assessed under commercial and industrial land use assumptions rather than residential or agricultural assumptions.
- This change reflects the Ministry’s view that urban park exposure scenarios more closely resemble commercial and industrial settings and may affect vapour risk assessments for redevelopment projects adjacent to public green spaces.
The updated protocol introduces additional guidance and clarity related to:
- Biodegradation Attenuation Adjustment Divisors (BAADs)
- Lateral Attenuation Adjustment Divisors (LAADs)
- Vapour Attenuation Factors (VAFs)
- Application of site-specific attenuation factors
These revisions provide environmental professionals with clearer guidance when assessing vapour migration pathways and estimating potential human health risks.
Improved Clarity and Consistency
In addition to the technical revisions, the Ministry has streamlined the protocol by removing content not directly related to vapour concentration estimation. The result is a more focused document that should improve consistency among environmental consultants and regulatory reviewers.
How These Changes Affect Property Owners and Developers
While the updates are primarily technical, they may have practical implications for redevelopment projects, environmental due diligence, and contaminated site closure strategies.
For sites impacted by petroleum hydrocarbons, chlorinated solvents, or other volatile contaminants, updated attenuation factors will influence how vapour risks are evaluated and managed, although the overall changes are expected to be relatively minor for most sites.
Why Work with an Environmental Consultant?
Navigating BC’s contaminated sites framework can be challenging, particularly as regulatory guidance evolves. Experienced environmental consultants can help property owners understand how Protocol 22 changes may affect ongoing investigations, remediation programs, and regulatory approvals.
Whether you are pursuing redevelopment, obtaining a Certificate of Compliance, completing a Phase II Environmental Site Assessment, or evaluating vapour intrusion risks, staying current with regulatory changes can help reduce uncertainty and avoid costly project delays.
The revised Protocol 22 comes into effect on January 15, 2027, providing consultants, developers, and property owners with time to adapt to the new requirements.
Although the changes do not fundamentally alter the vapour intrusion assessment process, they represent another step in BC’s ongoing effort to modernize contaminated site regulation and align technical guidance with current Canadian best practices.
