“Vapor intrusion occurs when vapor-forming chemicals migrate from a subsurface source into an overlying building.”
It wasn’t until the 1980s that the concept of vapor intrusion was fully understood, and today there are a host of regulations in place to ensure harmful vapors don’t adversely affect the ability to occupy a structure.
At Shield Engineering, we work with developers both pre- and post-purchase of commercial and industrial properties to help identify and in some cases, mitigate, vapor intrusion. Here are three tell-tale signs that invisible vapors could become a problem.
- Existing Intrusion Risk Factors
Some properties are at heightened risk of vapor intrusion from the get-go. Structures over shallow groundwater, for example, are more likely to be infiltrated by unwanted vapors pushed through the foundation by the undulating pressures of moving water. It’s important that any vapor intrusion testing take into account the EPA’s suggested screening approach which employs an “attenuation factor” that compares the ratio of pollutants in the soil above the groundwater table to those in the indoor air. Data-backed regression models are also relatively useful for estimating a property’s inherent vapor attenuation factor.
- Site-Specific Vapor Forming Chemicals
On many industrial sites, vapor-forming contaminants are already present in large amounts. There are literally dozens of chemicals in existence whose vapors can pose long-term health effects including VOCs, SVOCs, and more. If these chemicals are present onsite – contained in an underground storage tank, stored in a warehouse, used as paint on commercial surfaces – then the risk for vapor intrusion is automatically heightened. It is imperative that industrial sites be tested thoroughly not only for obviously harmful chemicals (such as lead) but for vapor-causing chemicals and chemical compounds whose effects might be invisible to the naked eye.
- Presence of Preferential Pathways
The negative effects of vapor intrusion only increase with the presence of preferential pathways. Preferential pathways such as mineshafts, tunnels, utility conduits, fractures, and karst formations can allow vapors to travel unusually long distances underground, seeping up through occupied buildings. These features should be evaluated on a site-specific basis to determine whether further testing of the building in question is necessary.
Vapor intrusion is unwelcomed at most levels. Vapor intrusion testing can be quite complex and often utilizes several engineering disciplines at once. Shield Engineering has decades of experience working with commercial and industrial building owners to detect, mitigate, and monitor harmful vapor intrusion.
Do you need assistance determining whether your property is at risk of a vapor issue? Would you like to find out more about what vapor intrusion testing entails, and how vapors can be mitigated if detected?