Vapor Intrusion Mitigation

Effective systems to remove hazardous vapor from the soil

Environmental soil pollution can enter buildings and homes through a process called vapor intrusion. Vapor intrusion is the migration of volatile organic compounds (VOCs) that have high vapor pressure and low water solubility. They can be present in contaminated soils or groundwater.

Volatile organic compounds are produced and used in the manufacture of fuels, paints, pharmaceuticals, and refrigerants. VOC's are also present in industrial solvents, paint thinners, tetrachorethene (TCE, which is dry cleaning fluid), fuel, oxygenates (MTBE), or chlorination in water treatment systems.

When these contaminants are present in the soil there is potential for vapor migration through the surface soils into surrounding buildings, thus potentially impacting the indoor air quality and posing a health risk to the building inhabitants. This exposure is receiving increased attention by regulators, in many states and represents a significant liability risk for building owners in an evolving regulatory climate.

Unlike radon gas, which occurs naturally, the hazardous elements mentioned above are man made. They enter the soil because of accidents or industrial activities. When buildings are constructed near or on top of contaminated soil, there's a risk of hazardous vapor intrusion.

If you're concerned about vapor intrusion, National Radon Defense can help. Read on to discover more, or contact your local NRD dealer to get started on needed vapor intrusion testing and mitigation.

The EPA provides vapor intrusion guidance

Since hazardous vapor intrusion into buildings is often associated with soil contamination, the Environmental Protection Agency has done considerable research in this area. The EPA provides basic information about vapor intrusion as well as detailed guidance for vapor intrusion mitigation (also called soil vapor extraction). This EPA vapor intrusion guidance is important for all people throughout the United States to accept and use to take action.

The most common solution is to install systems often used to reduce naturally occurring radon that seeps into homes in some geographic areas. These systems, called radon mitigation systems, remove soil vapors from below basements or foundations before they enter homes.

Our Vapor Intrusion Mitigation Techniques

Your local National Radon Defense Contractor will be able to provide you with several quality soil vapor extraction options, including:

• Sub-Slab Depressurization (SSD): SSD is widely considered the most practical vapor intrusion mitigation strategy for existing and new structures. EPA defines SSD technology as "a system designed to achieve lower sub-slab air pressure relative to indoor air pressure by use of a fan-powered vent drawing air from beneath the slab." Thus, even if there are holes, cracks, or other pathways between the building and the subsurface, vapors flow downward, not upward. Thus, a well-designed depressurization system prevents any toxic vapors from intruding above.
• Sump Pit Depressurization System (SPD): The sump pump cock is used as the suction pit. PVC pipe is run to the location of the fan. The fan is applying a vacuum to the sump pump pit and vapor can be collected and discharged outside. If you have a high water table in the ground this could be a good option for you.
• Sub-membrane depressurization systems: These systems are similar to sub-slab systems, but they are applied to buildings with crawlspaces, where there is either no slab or a partial slab. A vapor barrier (i.e., membrane) that is impermeable to gases is placed under the floor or directly on the soil, and one or more suction pits are placed beneath the membrane. Like subslab systems, they create a negative pressure under the building so vapors do not get sucked up into the building with lower pressure than the subsurface.
• Pressure field extension testing: A soil communication test, or PFE (pressure field extension) test, is a diagnostic test frequently used in radon and soil vapor extraction. This test requires a micromanometer and several pilot holes in the slab to determine how easily air can move under the foundation. This is also used after installation to determine the effectiveness of the system.

NRD contractors can also install vapor pins for diagnostics and annual maintenance. The vapor pin is a reusable sub-slab soil gas sampling device. The vapor pin is constructed of a single piece of metal. This single piece design along with the silicon sleeve eliminates potential leak points. It is installed to provide a sealable measurement point for annual maintenance of the system.

Sub-slab depressurization system

Crawl space membrane depressurization

National Radon Defense Experience

The international National Radon Defense network has worked with Environmental Engineering firms all over North America in installing Vapor Intrusion Mitigation Systems. National Radon Defense understands the importance of sealing, depressurizing, and communicating all the entry points of the vapor intrusion.

That is why we perform detailed pressure field extension testing to ensure the systems are working effectively. For an environmental cleanup project of this nature, we understand you need a company with experience to get the job done right. Our network of radon mitigation companies is North America's trusted source for vapor intrusion mitigation services.

Contact us today for soil vapor extraction, vapor intrusion guidance, and an estimate for vapor intrusion mitigation. We are also your resource for radon testing!

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