Odor & Hazardous Vapor Control
Common underground sources that can result in the generation of harmful and/or odorous vapors include:
- Volatile organic compounds (VOCs) in the soil and/or groundwater
- Total petroleum hydrocarbons (TPHs) in the soil and/or groundwater
- Nearby landfills that generate methane gas as a result of organic waste decomposition
- Naturally occurring gases, such as radon, from within rock formations.
Vapors rise through the soil pores and can enter buildings in a number of ways including through cracks in masonry foundations, via bare soil floors in crawlspaces or basements, through annulus spacing around utility pipes, and through floor drains.
Sub-slab depressurization (SSD) systems have become a primary means of controlling odor and vapor intrusion within commercial and, in some cases, residential structures. Moretrench subsidiary Ground/Water Treatment & Technology (GWTT) works with clients to aid system design and installation for both new construction and building retrofit.
SSD systems create a lower pressure beneath a floor slab relative to the pressure within the structure itself. The intent of the SSD system is to intercept subsurface vapors that are impacted with VOCs or TPHs, as well as other gases that may be present, so that they do not infiltrate into the air space within the structure itself. In those instances where the SSD system covers a large area, such as a warehouse, GWTT can assist with designing the system to provide the required air flow and higher vacuum.
If an existing concrete slab or floor is not present, it is also necessary to install a new floor, slab or vapor barrier such as an HDPE liner or membrane, in combination with the air handling system. This significantly reduces or eliminates the potential for vapors to rise through the slab or floor.
GWTT has assisted with the design of SSD systems and installed them in Delaware, New Jersey, New York, Pennsylvania and Massachusetts. Please visit our website for contact information as well as the opportunity to view summaries of completed SSD system projects.