Discussion of vapor intrusion and vapor encroachment
 July 30, 2013

Much research has been done on soil and groundwater contamination, however, vapor intrusion condition (VIC) and vapor encroachment condition (VEC), and their potential impact to human health and the environment, are two of the most highly debated environmental issues in California today. In order to fully understand the risks associated with VIC and VEC, and how they may impact California manufacturing firms, we must first understand where they originate.

What is Vapor Intrusion?
Vapor intrusion occurs when volatile chemicals migrate from contamination in the soil or groundwater up into a building's interior space. It can pose a potential health threat to the occupants of the building, especially to sensitive populations such as children.

VIC has been a particular concern with regards to contamination caused by perchloroethylene (PCE), because these chemicals are highly volatile and toxic. PCE has had a variety of uses throughout the years, but the most common uses were as a dry cleaning solvent, as a vapor degreaser, within the manufacture of paint, or as the cleaning agent in a parts washer. However, VIC is not isolated to PCE solvents, rather it can also occur with other contaminants such as petroleum products, which have long been known to pose a human health risk.

Vapor intrusion can be caused by contamination on-site or off-site from another property. Sometimes a plume of contamination from an off-site source (for example, a neighboring dry cleaner) can migrate onto the subject property and underneath (or in close vicinity of) the building, and thus pose a risk of entering the building.

What is a Vapor Intrusion Condition (VIC)?
A VIC is the presence or likely presence of chemicals of concern in the interior space of a building or at a planned building location. As such, the VIC term is applied not only to scenarios where contaminants have been documented in indoor air, but also to scenarios where there is the potential for these vapors to be intruding into the building.

"Vapor intrusion condition" is essentially a subset of the term "Recognized environmental condition," which is used in the Phase I environmental site assessment (ESA). The Phase I ESA identifies any recognized environmental condition, which should also include the identification of Vapor Intrusion Conditions. A recognized environmental condition (REC) is defined by ASTM as "the presence or likely presence of any hazardous substances or petroleum products on a property under conditions that indicate an existing release, a past release, or a material threat of a release of any hazardous substances or petroleum products into structures on the property or into the ground, groundwater, or surface water of the property . The term includes hazardous substances or petroleum products even under conditions in compliance with laws."

Recently, VIC has been of significant concern in the environmental consulting community due to a variety of reasons, such as changing regulations, increased efficacy of testing methods, and VEC.

What is Vapor Encroachment Condition (VEC)? The term "vapor encroachment" was coined to describe the migration of these vapors anywhere onto a property or near a property (not necessarily underneath or into a structure on the property). The ASTM definition of a VEC is "the presence or likely presence of chemical of concern vapors in the subsurface of the target property caused by the release of vapors from contaminated soil and/or groundwater either on or near the target property." For example, this term could apply to contamination that has migrated just over the property line, but is still 200 feet from any inhabited structure on the property.

Vapor encroachment is a broader concern than vapor intrusion, which really focuses just on the potential for vapors to exist inside a building.Vapor encroachment is the term used in the ASTM E2600-10 Standard for vapor encroachment screening. A previous version of the ASTM Standard, ASTM E2600-08, used the term vapor intrusion and many in the environmental consulting field still use this term, for reasons discussed below.

VIC versus VEC, and is it a Recognized Environmental Condition?
There is debate within the environmental consulting community regarding the use of the term vapor encroachment concern versus vapor intrusion concern, whether either of these items represents a recognized environmental concern (REC), and how to address these issues within the Phase I environmental site assessment report. This can all be quite confusing to users of the Phase I ES A.

It is important to distinguish between what is a human health concern and what is not.

ASTM already makes this distinction in its definition of what constitutes a REC versus what constitutes a less significant issue (a "de minimis" concern). From the ASTM E1527-05 standard for Phase I ESAs: "The term (REC) is not intended to include de minimis conditions that generally do not present a threat to human health or the environment and that generally would not be the subject of an enforcement action if brought to the attention of appropriate governmental agencies."

Most environmental professionals would agree that a VIC, where contamination is potentially migrating to the interior of a building, has always been a REC, because it represents a human health concern. Since the main goal of environmental regulations is to protect human health and the environment, a strong argument can be made that it should not be considered a de minimus condition.

There is less clarity regarding the use of VEC (where contamination isnít necessarily underneath the building but located anywhere on the property). Many argue that so long as there is no risk of the vapor migrating into the building (thus posing no health risk), and the contamination originates from an off-site source for which the target property owner would not be liable, the VEC would not be considered a REC.

Regardless of the source or migration pattern of vapor, it will continue to pose a significant concern for businesses throughouttheState. Asnewstricterregulationsare continue to be a trend towards tighter regulation and enforcement here in California. Therefore, thought should be given to how these risks impact our business operations, and what is being done to prepare for the ever changing regulations in the future.

See more at: http://www.partneresi.com/services/ vapor-intrusion-encroachment-assessment.php

by Nicole Moore, Technical Director - Environmental Sciences Partner Engineering and Science, Inc.
Partner Engineering and Science, Inc. (Partner) is a full service engineering and environmental consulting firm, specializing in evaluating properties in connection with commercial real estate transactions, financing, development or management. Headquartered in Torrance, CA, Partner is a national firm with regional offices located around the country. http://www.partneresi.com


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