Formatted Title
Hazardous is the New Clean: Contaminant Management Supported Redevelopment
Background/Objectives
The presentation will revolve around a case study on a Contaminant Management Strategy that is currently being implemented on a brownfield in the Greater Toronto Area (ON, Canada). Polychlorinated biphenyls (PCBs), chlorinated volatile organic compounds (CVOCs), petroleum hydrocarbons (PHCs), potential off-Site migration and free product - the Site has a varied and storied past, complete with several ultimately unsuccessful remedial efforts and the well-intentioned but unfortunately mismanaged handling of hazardous levels of PCBs. However, through the discussion of the implementation of a robust property boundary control with permeable reactive barrier (PRB), hotspot remediation and isolation, and vapor intrusion mitigation and management, this presentation will highlight how this diamond in the rough is being polished into a safe and economically viable asset.
Approach/Activities
The presentation will focus on the design and installation of a >1000 ft long funnel-and-gate style permeable reactive barrier. This innovative boundary control represents the first of its kind to use a catalyzed zero valent iron (ZVI)-impregnated engineered carbon-based reactive media as the primary treatment amendment while also including an ‘Containment Zone’ designed to hydraulically isolate and contain free-phase CVOCs and PCBs located in fractured bedrock. The presentation will include review of bench-scale column tests, proof of concept PCB permeability testing, conceptual designs and modelling, and the challenges and experienced gained during infield full-scale implementation.
Results/Lessons Learned
The presentation will involve discussion of the results of bench-scale column testing and how the measured half-lives were used to inform full-scale design of a PRB design to mitigate the off-Site CVOCs, PHCs, and PCBs. Additionally, focus will be paid to the necessary infield adjustments that had to be made when translating a boundary control design from the ideal form on paper to the more rough and less forgiving environment of a former industrial site impacted with hazardous levels of contaminant. Attention will be paid to how this program fits into the larger site wide contaminant management strategy and how this approach is allowing for the beneficial reuse of properties that would have otherwise stood vacant.