Dec 6, 2019

Vapour Intrusion on Property

When the redevelopment of a property is hindered due to volatile contaminants on the site, appropriate risk management measures can be employed to permit the redevelopment to proceed. XCG’s clients rely on our expertise and responsiveness in applying mitigation efforts to prevent vapour intrusion risks. Here are a few recent project examples that demonstrate how our Expert People help you make Better Decisions.

Design and Construction Monitoring – Methane Venting System

Based on our previous work on a commercial property that was next to a historical municipal landfill, the new owner of a retail plaza requested XCG to assist with the design and construction monitoring for a new building on that property. Due to the close proximity of the old landfill, a condition of development

was that full protection from possible methane intrusion was to be provided for any and all buildings constructed.

XCG’s previous work on the property included securing an updated Environmental Compliance Approval (ECA) from the province for the constructed methane protection systems on the existing buildings.

The new owner/developer and their construction manager requested XCG to provide design services for the methane protection system on a new 6-unit, 835-square metre commercial building that was added to the property. The design included impermeable membrane liner and methane collection piping below the building that leads to four passive vents equipped with turbines on the building roof. Further, below-grade impermeable membrane liner and diversion zones leading to passive vents were also constructed below the parking areas around the new building. The new building features were constructed in compliance with the updated ECA.

XCG provided economical construction verification and reporting to support the regulatory approval and municipal requirements and ensured that all construction and development schedules were met. To the great satisfaction of the owner/developer, the new building is now occupied with commercial tenants and the site development is complete.

Vapour Collection and Risk Management - Former Dry Cleaner Site

When a prominent Canadian realty management firm was expanding retail developments in their Hamilton, Ontario retail plaza property, XCG was called to quickly investigate the impacts from a historic dry-cleaning operation that occupied the property circa 1965. The chlorinated volatile organic compound (cVOC) impacts from the former dry-cleaning operations were identified and quantified in soil, bedrock, and groundwater. Due to the volatile nature and carcinogenic properties of the cVOCs, a screening level risk assessment (SLRA) was completed and XCG determined that specific measures could be implemented which would allow the development of a stand-alone retail unit over the existing impacts.

XCG played an integral role on the client development team and worked with our trusted contractors to design and construct the risk management measures which included installation of injection drains and piping for future in-situ chemical oxidation/reduction (if needed) followed by vapour collection piping and media for sub-slab depressurization. A fully sealed impermeable membrane was installed below the slab-on-grade floor and a passive vent with a turbine was installed on the vapour collection piping to assist with vapour diversion. The vent stack was constructed to permit the future addition of an active venting and treatment system, if necessary.

The project was executed over a nine-month period which ensured that the client was able to meet their development commitments for their new valued tenant - with keys delivered a month earlier than expected. The innovation and quick-turnaround demonstrated by XCG and team made this project a finalist for a 2017 Canadian Brownfields Network (CBN) Brownie Award in the Remediate category.

Mitigating Vapour Intrusion at a Condo Development

XCG was requested by a property owner and developer to assist with the implementation of risk management measures (RMMs) outlined in the Certificate of Property Use (CPU) that was issued for a former factory property in Guelph, Ontario. With plans for construction of three townhouse condominium buildings on the property, it was paramount that any potential for vapour intrusion from the remaining contaminants was mitigated. Contaminants included chlorinated volatile organic compounds (cVOCs), polycyclic aromatic hydrocarbons (PAHs), and petroleum hydrocarbons (PHCs) in the soil and groundwater.

Some of the risk management features that were incorporated into the townhouse condominiums included below-grade vapour diversion piping and sealed impermeable membrane liners below each unit with vent stacks and turbines that have the ability to be scaled up to active fans, if necessary. Further features of the system include impermeable membrane liners and engineered surface caps to prevent vapour short-circuiting. XCG worked closely with the site developer in the construction of the buildings that incorporated these engineered features.

XCG’s expertise in risk-management implementation and our strong relationship with local regulators, suppliers and contractors was relied upon to get the project realized. The staged development is now nearing completion and XCG continues to provide CPU-required indoor air monitoring services for the residential development

XCG Knows… Contacts

If you have a risk management or vapour mitigation concern on your property, XCG Knows how to help - contact us today for a confidential discussion on next steps. Contact Pamela Cameron or Kristian Peter today to find out how XCG can help.