Vapor Intrusion: An Emerging Risk that Could Cost Property Owners

Years after property owners thought they had completed the clean-up and environmental remediation of old contaminated sites, vapor intrusion has emerged as a risk that could result in additional clean-up costs and liability exposures.

The U.S. Environmental Protection Agency (EPA) defines vapor intrusion as the “migration of volatile chemicals from the groundwater or soil into an overlying building.”  Some building owners or managers may not be aware that they have a potential vapor intrusion problem at their property. In urban districts, many buildings are built in areas where soils or groundwater have elevated levels of contaminants.  However, even in areas with newer construction, the subsurface conditions could create bodily injury, remediation, or property damage exposures. In many situations, historical property uses may have impacted soils and groundwater. In a non-industrial setting, common sources of sources of volatile chemicals can include: dry cleaners, service stations or auto body shops, or leaking underground fuel storage tanks. Contaminants that are commonly found at impacted properties include:

  • Total Petroleum Hydrocarbons (TPH), including Benzene
  • Chlorinated Volatile Organic Compounds (CVOCs) such as Perchloroethylene (PCE), Trichloroethylene (TCE), 1,1,1 –Trichloroethane (1,1,1-TCA) and Vinyl Chloride
  • Landfill gas (methane)

Volatile chemicals can diffuse and migrate through the subsurface. When the vapors reach an obstruction (such as pavement, concrete foundation, or slab) they can collect.  As cracks develop in these obstructions, the pressure difference between the building and the subsurface allows the vapors to migrate upward into the buildings.  The vapors may accumulate in work spaces or living areas within buildings to levels that pose hazards affecting properties,, acute health effects or odors. In some cases, such as residences with low concentrations of these vapors, chronic, long-term exposure may also present a risk.

Vapor intrusion first became an issue because of several high profile Superfund cleanups.  While many of the thousands of contaminated sites in the United States have been cleaned up, vapor intrusion issues may emerge when these sites undergo post-remediation inspections. The EPA and state environmental regulatory agencies are required to perform post-remediation inspections on a regular basis to determine whether a site, which had been cleaned up and was granted a “No Further Action” decision, remains within acceptable state.

In many cases, vapor intrusion was not considered in the original risk assessment and remediation planning. Most states have dozens if not hundreds of sites that will be re-examined.  To add to the concern, there is debate among regulators, including environmental and safety professionals, as to what can be considered safe concentrations of volatile chemicals in breathing spaces.  Inconsistent interpretation of the chemical exposures and response actions creates an uncertainty in a property owner’s risk management strategy.

A recent development in the enforcement of levels to which a party must cleanup the contaminants highlights the regulatory inconsistency across the country.  For example, in 2014, the EPA in Region 9 (California) recently set strict guidelines for trichloroethylene (TCE) levels in buildings caused by vapor intrusion. The guidelines cover sites that are listed on the National Priorities List (Superfund list) and call for a tiered cleanup and response.  Depending on the concentration of TCE in the building, the stricter requirements could potentially require evacuation of buildings if TCE levels are deemed too high.  Under prior guidance, installation of a vapor instruction remediation system may have been sufficient.   The impact on safety concerns, as well as the costs from loss of use of a building, could have significant effect on property owners and insurers alike.

In addition to those sites that are monitored by regulators, there are a significant number of properties that may still have undiscovered vapor intrusion conditions. This is common in many commercial buildings where occupants or neighboring properties (past and present) used volatile chemicals as part of their operations.  A common example would be dry cleaners.  Most dry cleaners use tetrachloroethene (PCE).  The PCE and some of its by-products (trichloroethene, dichloroethylene, and vinyl chloride) can contaminate soils and groundwater and accumulate beneath a building foundation.  This accumulation can occur over time, and may not be discovered until years after the dry cleaning operations ceased.

A recent example of this occurred in a commercial building in New York. There, over a span of several years, leaking dry cleaner equipment released fluids to underlying soils, causing contamination on the property. Over time, the state regulator determined that the contamination from these releases had spread beneath multiple properties, and was migrating toward several additional commercial and residential properties. As a result, the regulator is performing environmental studies to determine the extent of the contaminant plume. The ultimate cleanup cost may become the responsibility of the owner of the property that leased the space to the dry cleaner, but property owners affected by the contaminant plume may also incur costs to ensure the vapors are not impacting their properties.

To learn more about how to mitigate the risk of vapor intrusion, stay tuned for Part II, “Vapor Intrusion: Keeping the Air Clean.”

Eugene Wingert is a risk engineering environmental specialist with Chubb North America Commercial Insurance.

Categories: Management Liability, Safety
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