Soil Vapour Monitoring
XCG was retained to conduct a Phase I Environmental Site Assessment (ESA) a Phase II ESA, groundwater quality investigations and a soil vapour investigation at the site of a chlorinated solvents release at a former dry-cleaning facility in Southern Ontario. Historical releases of chlorinated solvents at the site resulted in a groundwater plume of dissolved phase chlorinated volatile organic compounds (cVOC) contamination, and cVOC vapours in the subsurface.
Undertaken subsequently to soil and groundwater remediation activities, the soil vapour investigation was intended to assess soil vapour conditions at locations within the subsurface of the remediated (excavated) source area, and at adjacent residential properties.
The soil vapour quality in the vicinity of the adjacent residential properties and the remediated (excavated) source area was assessed through the installation and sampling of soil vapour monitoring probes.
Following remedial excavation activities, the soil vapour concentrations of cVOCs detected in a vapour probe located within the remediated (excavated) area on the site of the former dry-cleaner decreased significantly (approximately two orders of magnitude) from the pre-excavation concentrations.
The soil vapour concentrations of cVOCs detected in the subsurface of the adjacent residential properties decreased moderately since the remedial excavation, but continued to exceed the calculated soil vapour criteria for residential property use.
The soil vapour investigation described above is ongoing, with XCG continuing to provide consulting services to assess the anticipated continued reduction in concentrations of cVOCs in soil vapour.