Soil Vapour Assessment and Ontario Regulation 153/04 Environmental Site Investigations in Ontario
Based on the evaluation of modelled soil vapour concentrations it is common for soil contaminants of concern (i.e., volatile contaminants) to pose a potential health risk to receptors via the soil-to-indoor air vapour migration pathway. However, it is understood that the approach used to model vapour concentrations in indoor air, though acceptable to the Ontario Ministry of the Environment, is highly conservative based on the assumptions related to the maximum soil concentrations and potential for natural attenuation of soil vapours. Consequently, as a result of these predicted risks, risk management plans must often be designed to mitigate the theoretical risk from the vapour intrusion pathway. Such risk management measures are implemented at a considerable cost to site owners/developers. To avoid these potentially unnecessary risk management measures it is now common practice to collect soil vapour samples to measure the concentrations of contaminants of concern in soil vapour, resulting in a more accurate assessment of the risk posed by vapour intrusion. The research that will be completed will help Stantec streamline soil vapour intrusion programs completed in Ontario by understanding the benefits of used measured soil vapour data, from the initial set-up of the program through to the writing of reports.