Project Description

This project involved an environmental site assessment at a pharmaceutical plant in Southern Ontario. The assessment investigated diethybenzene and VOC spill concentrations in the vicinity of the east property boundary.

Subsurface soils consisted of surficial topsoil or asphalt pavement with 1 to 4 m of clayey silt fill over native undisturbed compacted, wet, brown silt and soft to stiff, grey, very moist silty clay to clayey silt.  The short term groundwater level was at 2 to 5 m depth.  This property is located within a Region of York Wellhead Protection Area in Southern Ontario, with potable water considerations.

Previous to our engagement on the project, 10 boreholes and 9 monitoring wells were installed on site. Between 2012 and 2014, Sarafinchin added another 5 boreholes and monitoring wells for broader analytical testing of soil and groundwater samples. The selected areas of the primary site included drilling 4 exterior boreholes and 1 interior borehole to 6 m depth. Soil and groundwater samples were analyzed to determine the specific nature of diethybenzene and VOC concentrations, as well as other volatile organic compounds.

Sarafinchin estimated a plume to be localized onsite at the central tank storage area and in the service trench areas at the east and front side of the building. From an environmental management perspective, and with progressive site assessments recommended, a phased environmental management plan and risk management plan were initiated. This included a review of the possible sources of contamination, the likely pathways for contamination, and any nearby sensitive receptors. A cutoff trench, soil disposal and soil treatment, groundwater treatment, and site monitoring options were proposed for implementation.