by James P. Cinelli, P.E., P.G., BCEE, Liberty Environmental
Vapor intrusion is a growing concern in environmental health, specifically in highly developed urban areas where soil gases or contaminated groundwater can migrate into buildings. Vapor intrusion occurs when volatile organic compounds (VOCs) and other harmful contaminants seep through cracks or other openings in a building’s foundation and it can potentially pose significant health risks to occupants. To combat this issue, Sub-Slab Depressurization Systems (SSDS) have emerged as an effective solution.
Understanding Vapor Intrusion
Vapor intrusion occurs when hazardous vapors from contaminated groundwater or soil migrate into indoor spaces. This typically takes place through small cracks and other openings in the foundation of a building. There are significant health risks posed to occupants of a building who experience long-term exposure to these contaminants ranging from respiratory issues to more severe conditions, including cancer.
What are Sub-Slab Depressurization Systems?
Sub-Slab Depressurization Systems are an engineered solution designed to reduce indoor vapor concentrations. These systems create a vacuum beneath a building’s foundation, drawing vapors away from the sub-slab area and preventing their entry into the indoor environment. The primary components of an SSDS (Sub-Slab Depressurization System) include:
1. Suction Points: These are pits or perforated pipes installed beneath a building’s slab foundation that collect vapors.
2. A Fan: Air circulation from a fan or blower creates negative pressure (depressurization) beneath a slab foundation.
3. Vent Stack: This directs collected vapors beneath a foundation safely outside and away from windows and air intakes to ensure they do not re-enter a building.
Implementation Process
The implementation of an SSDS begins with a thorough site assessment to identify the source and concentration of contaminants. Engineers can then design a tailored SSDS system to address specific building and site conditions. Once designed, installation typically brings minimal disruption, as it can often be completed without significant alterations to an existing structure.
After installation, an SSDS system does require regular monitoring and maintenance to ensure its effectiveness. This includes inspecting suction points for blockages, checking the fan for operation, and conducting air quality tests to verify that vapor concentrations remain at safe levels.
Liberty Environmental’s talented team of remediation experts has proven experience addressing vapor intrusion and assisting in the process of integrating sub-slab depressurization systems. Contact us at info@libertyenviro.com to schedule a site assessment or speak with a member of our team to learn more.
