TECHNICAL ADVISORY

NOW AVAILABLE
Updated Atlantic RBCA Guidance for Vapour Intrusion Assessments (December 2016, updated April 2019)

Atlantic PIRI has revised the technical document Atlantic RBCA Guidance for Vapour Intrusion Assessments (December 2016). The revised technical document Atlantic RBCA Guidance for Vapour Intrusion Assessments (December 2016, updated April 2019) is now available and takes effect immediately. There are two important changes to the technical document.

Revision to Vapour Intrusion Screening Levels (VISLs)

In Appendix B, Table B1, Tier II Vapour Intrusion Screening Levels (VISLs), there is a revision to the calculations for the Residential/Agricultural Vapour Intrusion Screening Levels (VISLs) for Soil Vapour, following the discovery of a miscalculation in the tables. Also note that certain sub-slab and soil vapour VISLs have changed slightly due to rounding of values in the calculations.

Revision to Biodegradation Factor

Appendix B, Table B1, has also been updated to include a biodegradation factor of 10 into the calculation of Residential/Agricultural and Commercial/Industrial VISLs for Soil Vapour. This change reflects harmonization with the CCME as per the CCME Harmonization Agreements respecting environmental standards where each Atlantic Minister ensures an equivalent level of environmental protection with CCME standards.

Implementation Procedures

Effective immediately, Provincial regulators in Atlantic Canada will require Site Professionals to use the updated Atlantic RBCA Guidance for Vapour Intrusion Assessments (December 2016, updated April 2019) for all ESAs.

If you have questions about the revisions in the Atlantic RBCA Guidance for Vapour Intrusion Assessments (December 2016, updated April 2019) you may contact Atlantic PIRI or your provincial environmental regulator.

Atlantic RBCA Guidance for Vapour Intrusion Assessments

The Atlantic RBCA Guidance for Vapour Intrusion Assessments (December 2016, updated April 2019) supercedes the User Guidance for Soil Vapour and Indoor Air Monitoring Assessments (Atlantic PIRI, 2006).

The Guidance document originally released in Dec. 2016 (and updated April 2019) does not include specific reference to chlorinated solvents. This was based on Health Canada’s recommendation that the most recent toxicity reference values published by the US EPA be used for the assessment of sites contaminated with perchloroethylene (PCE, also known as tetrachloroethylene) and trichloroethylene (TCE). Please refer to Implementation Procedure and Technical Bulletin #2 for PCE and TCE (December 2016, updated April 2019) for further details.

In April 2019, the Guidance (and all accompanying documents) were updated to reflect revisions made to the calculations for the Residential/Agricultural Vapour Intrusion Screening Levels (VISLs) for Soil Vapour, following the discovery of a miscalculation in the tables. Also note that certain sub-slab and soil vapour VISLs have changed slightly due to rounding of values in the calculations. In addition, the Guidance was updated to include a biodegradation factor of 10 into the calculation of Residential/Agricultural and Commercial/Industrial VISLs for Soil Vapour.

If you have questions about the Atlantic RBCA Guidance for Vapour Intrusion Assessments (December 2016, updated April 2019) you may contact Atlantic PIRI or your provincial environmental regulator.