Redevelopment of brownfield sites plays an important role in stimulating the economic revitalization of communities by bringing vacant or underutilized properties into productive use and offsetting the need to develop open land, or “green space.” Along with the normal financial and business risks associated with developing property, brownfields redevelopers must manage environmental risk, including that due to vapor intrusion-the migration of chemical vapors from contaminated soil and groundwater into buildings. EPA’s primer, Vapor Intrusion Considerations for Brownfields Redevelopment, is designed for land revitalization stakeholders concerned about vapor intrusion, including property owners, municipalities, and real estate developers. It provides an overview of the vapor intrusion issue and how it can affect redevelopment. It also summarizes techniques for quickly and cost effectively assessing the potential for vapor intrusion, as well as techniques for mitigating it.
The core message of the primer is that early consideration of vapor intrusion beginning during the Phase I environmental site assessment will help ensure that redevelopment protects the health of current and future building occupants. In addition, incorporating relatively inexpensive mitigation (prevention) techniques into the construction of new buildings, rather than retrofitting them later, will result in significant cost savings and help avoid the occurrence of vapor intrusion in the future. Because there are many available, cost-effective approaches to mitigation, vapor intrusion need not stand in the way of brownfields redevelopment.
Vapor intrusion is an exposure pathway-a way that people may come in contact with environmental contaminants. Vapor intrusion exposes building occupants to potentially toxic levels of vapors when volatile chemicals (those that readily evaporate) present in contaminated soil or groundwater emit vapors that migrate into overlying buildings. It is similar to the more familiar problem of radon, a gas that is emitted naturally from soil and bedrock and enters buildings through cracks and openings in the foundation and through porous building materials. Both volatile chemicals and semivolatile chemicals (those that evaporate more slowly) can pose a vapor intrusion problem.
Vapor intrusion poses a potential risk to the health of residents, workers, and other occupants who breathe the vapors inside buildings. In the past, cleanup of brownfields and other contaminated sites focused on protecting human health by preventing exposure to contaminants through direct contact (e.g., children playing in contaminated soil) or ingestion (e.g., residents drinking contaminated groundwater from wells). As we have learned more about vapor intrusion, however, it has become clear that the potential for risk of inhaling chemical vapors due to vapor intrusion may still need to be addressed.
Vapor intrusion is a potential concern at any building-existing or planned-located near soil or groundwater contaminated with VOCs. Properties with potential VOC contamination are common in industrial and commercial areas. They include current and former manufacturing and chemical processing plants, warehouses, landfills, coal gasification plants, train yards, dry cleaners, and gas stations. Improper use, storage, or transport of chemicals at these facilities may have resulted in a release of contaminants to the environment creating the potential for future vapor intrusion issues. In addition to industrial and commercial activities, roadside dumping, pesticide spraying, or even improper disposal of household chemicals via a septic field may also release contaminants to the environment. Therefore, the potential for vapor intrusion should be considered at all types of properties considered for redevelopment.
Awareness of vapor intrusion as a potential for exposure to soil and groundwater contamination has raised concerns about public health risks and liability during property transactions. However, if vapor intrusion is considered along with other potential exposure pathways commonly evaluated (e.g., ingestion of or direct contact with soil and groundwater), land revitalization stakeholders can eliminate potential health risks and facilitate transactions. Early proactive evaluation of vapor intrusion can make available more options for the mitigation and redevelopment. In addition, preconstruction mitigation measures are less expensive than post-construction remediation and structure retrofits.