Vapor Intrusion Studies
Vapor intrusion refers to what happens when chemical vapors migrate from the soil or groundwater into a home or other building. Many chemicals that move into buildings this way are classed as volatile organic compounds (or VOCs). The term volatile means unstable" which in turn means these chemicals are likely to exist in gas (aka vapor) form.
Because they’re gaseous, VOCs can move easily through spaces between soil particles and tend to migrate from high-pressure to low-pressure areas. Since a basement is probably at lower pressure than the soil underneath, these vapors are likely to enter the basement (or other first level) through cracks in the foundation, walls, or floors. Some heating and air conditioning systems will literally pull the gases into the structure. Once they’re inside, natural air flow and ventilation allow the vapors to spread throughout the building. Vapor intrusion can cause indoor air to become polluted and unhealthy.
What are the risks?
The degree of health risk vapor intrusion poses depends on the type of chemical and concentration of the chemical in the home. The most common sources of chemicals that can cause vapor intrusion problems are gas stations and dry cleaners.. For example, a nearby gas station might have a leak or spill from an underground storage tank allowing gasoline to release to the soil and possibly groundwater. Short-term exposure to gasoline-related vapors can cause respiratory irritation, nausea, or headaches, and long-term exposure can contribute to long-term effects such as cancer.
Vapor intrusion clearly can cause health risks to families. In addition, vapors might pose a liability issue if they intrude into a workplace.
How do I know if I have vapor intrusion?
There are several ways to test whether toxic chemicals are entering a building: you can collect soil vapor samples in the ground nearby a structure or in the ground right under your foundation; or you may elect to collect indoor air samples.
If you learn that a nearby gas station or industry has had a toxic spill or leak, you might call the owners or government officials to request that they test your home for vapor intrusion. The Environmental Protection Agency (EPA) provides a lot of information about vapor intrusion and safe chemical levels:http://www.epa.gov/oswer/vaporintrusion/
What should I do?
Landlords, property owners, developers, and investors should take vapor intrusion very seriously. They should include Vapor Encroachment Screenings, Vapor Intrusion Testing in their due diligence activities.
If tests indicate that chemicals are intruding into your home or commercial structure, there are several actions you could take. You might seal any cracks in your walls or foundation. Or you could have a mitigation and/or remediation system installed.
Landlords, property owners, developers, and investors should take vapor intrusion very seriously. They should include testing and mitigation for these contaminants in their due diligence activities.
Andersen has certified environmental consultants who conduct Vapor Encroachment Studies according to the guidance of the EPA’s ASTM E2600-10 “Standard Practice for the Assessment of Vapor Encroachment Screening on Property Involved in Real Estate Transactions.” A Vapor Encroachments Study is a method for evaluating the potential for a vapor intrusion condition.
Andersen stands ready to conduct a vapor encroachment study identified by the following tiers of service:
Tier 1 involves an initial screening for the potential of vapor encroachment conditions (“pVECs”) at a property. This tier could be an inexpensive add-on to a Phase I Environmental Site Assessment , and includes an evaluation of current and historical uses, a review of governmental records, and examination of the physical setting of the subject property and adjoining and nearby properties. Tier 1 assessment determines whether contamination sources are located close enough to create a pVEC. If we either find or can’t rule out a pVIC, further assessment is recommended.
Tier 2 is a highly-refined screening to identify if any pVECs may pose a potential vapor intrusion condition (“pVIC”) at a property due to a VEC. In a Tier Two assessment we attempt to identify pVICs by closely evaluating soil and groundwater data relating to the site(s) where the chemical release occurred. Based upon the chemicals released and the migration of the chemicals in soil and groundwater relative to the subject property we determine if a VEC exists. By further evaluating chemical concentrations, soil lithology, depth to groundwater and other site specific criteria, we render an opinion of a VIC is or is not likely. If a VIC is considered likely, a Vapor Intrusion Study May be recommended.
If the Vapor Encroachment Study determines that a Vapor Intrusion Condition is likely, a Vapor Intrusion Study may be performed. The preferred method for performing a Vapor Intrusion Study involves the collection of soil vapor samples directly adjacent to or beneath the existing structure or the area of a proposed structure. Soil vapor samples collected are compared to prevailing soil vapor screening levels established by the State of Local Regulatory Agency, when available. If soil vapor concentrations exceed established screening levels, then a Human Health Risk Assessment may be necessary to determine site specific risks based on many factors including building characteristics. If the Human Health Risk Assessment finds an elevated risk to human health exists, indoor air sampling, mitigation, or remediation may be necessary.
To learn more about vapor intrusion today, call us at 310-854-5453.