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SLR Consulting (Canada) Ltd./Alexis Holdings Limited

Vapour Mitigation System Design & Installation

We designed and installed a vapour mitigation system for a high density commercial and residential use building with two subgrade levels located in Vancouver, British Columbia.

The site had multiple commercial uses in the past and historical dry cleaning operations were the source of chlorinated solvents contamination at the site.

To address the residual contamination in excess of Contamination Sites Regulation (CSR) numerical standards, a vapour collection system was installed to mitigate the potential risk of subsurface vapour intrusion into indoor air in support of an application for a risk-based Certificate of Compliance (CoC) for the site.

The vapour mitigation system included the following:

  • An impermeable vapour barrier installed beneath the building slab.
  • A venting system to continuously remove vapours accumulating under the two-subgrade levels. The sub-slab venting system is designed to operate as a passive system with the flexibility to convert to a depressurization system if passive venting. does not adequately remove subsurface vapours.
  • A soil vapour collection piping network and custom built sampling points.

McCue services included:

  • Detailed design of a vapour mitigation system in accordance with the BC Ministry of Environment technical guidance.
  • Installation, inspection and commissioning of the system.
  • Preparation of a Letter of Assurance to confirm that the system is installed per design requirements.
  • Monitoring, maintenance and vapour sampling of the vapour mitigation system according to the maintenance plan.

Vapour barrier installation in Vancouver, British Columbia

Vapour extraction piping installation as part of a vapour mitigation system in Vancouver, British Columbia