Soil Vapour Investigation

As part of an ongoing insurance claim, XCG was retained to conduct a soil vapour investigation at the site of a large fuel oil release at a former school in Northern Ontario. Historical releases of fuel oil at the school property resulted in an extensive groundwater plume of free product and dissolved phase petroleum hydrocarbon (PHC) contamination, and associated petroleum vapours in the subsurface. Undertaken concurrently with ongoing groundwater remediation activities, the soil vapour investigation was intended to assess soil vapour conditions at locations with the most significant presence of free product, and to assess how the presence of petroleum vapours might limit site activities.

Soil vapour analytical results were compared to criteria derived to be protective of soil vapour migration to outdoor air, as well as criteria derived to be protective of soil vapour migration to indoor air. No occupied buildings were present on the property at the time of the investigation and so the soil vapour results were compared to the soil vapour assessment criteria protective of outdoor air. Based on the results of the vapour sampling, despite the presence of extensive free product zones in groundwater across the property, there was no evidence of  potential health risks from migration of soil vapour to indoor or outdoor air. However, an additional vapour sampling event was recommended to confirm the findings and assess seasonal variability, and XCG recommended that no buildings be constructed on the property without further investigation and/or risk management measures.

Following the initial soil vapour investigation, XCG was also retained to complete additional tasks as required by an Order from the Ministry of Environment, Conservation and Parks (MECP). These tasks include monthly, seasonal and annual requirements for sampling of groundwater, surface water, and residential drinking water.  During the sampling events, any detectable free phase product measured within groundwater wells is manually removed. This project involves regular correspondence with the Municipality, the MECP and residents.