tarily accepted a risk associated with environmental contamination in connection
with their employment” but would apply
the OSHA PELs to a workplace where the
employer has incorporated the environmental exposures (unrelated to plant operations) into its employee protection program.
The varied state approaches present a perception problem in terms of exposure risk
for different receptors (public versus workers) since the VI screening levels are several
orders of magnitude lower than published
occupational exposure limits (see Table 2).
Technical Guidance
ASTM International (formerly the
American Society for Testing and Materials) introduced its new vapor intrusion
standard (E 2600-08), “Standard Practice
for the Assessment of Vapor Intrusion into
Structures on Property Involved in Real
Estate Transactions,” in March 2008. This
standard defines a four-tier process for
screening, investigating and mitigating
vapor intrusion conditions (see Table 3).
From Tier 1, industrial hygienists can
proceed to any other tier, including mitigation. ASTM surveyed users for feedback on the new standard; the survey
comments have led to several proposed
revisions. The revised ASTM standard is
expected to be released in 2010.
The U.S. Department of Housing and
Urban Development is the first federal
agency to issue a new requirement for
an ASTM Tier 1 vapor intrusion screening in addition to a phase 1 environmental site assessment at multifamily
properties applying for Federal Housing
Administration mortgage insurance.
Litigation Updates
The liability for VI exposure falls under
the following regulations:
• Comprehensive Environmental Re-
sponse, Compensation, and Liability
Act (CERCLA)
• Resource Conservation and Recovery
Act (RCRA)
• Underground Storage Tanks (UST)
programs
• state remedial programs
• common law
• disclosure laws
Most litigation pertains to the off-site
migration of contaminant vapors. Some
sites that were previously mitigated—i.e.,
those that were granted a “No Further
Year Guidance
1991
EPA’s Johnson and Ettinger
Model for Subsurface
Vapor Intrusion into Buildings
1999
New Jersey Department of
Environmental Protection
(NJDEP) “Indoor Air Sampling Guide for Volatile
Organic Contaminants”
(VOCs)
2002
EPA Office of Solid Waste
and Emergency Response
Draft Guidance for Evaluating the Vapor Intrusion to
Indoor Air Pathway from
Groundwater and Soils
2005
NJDEP Vapor Intrusion
Guidance
2007
Interstate Technology and
Regulatory Council “Vapor
Intrusion Pathway: A Practical Guideline” and supplement “Vapor Intrusion
Pathway: Investigative
Approaches for Typical
Scenarios”
2008
ASTM “E2600-08 Standard
Practice for Assessment of
Vapor Intrusion into Structures on Property Involved
in Real Estate Transactions”
2008
EPA “Brownfields Technology Primer: Vapor Intrusion
Considerations for Redevelopment.”
Significance
A risk assessment tool applied to potential
VI sites to predict indoor air concentrations
of contaminants and to identify the need for
indoor air sampling and site remediation.
Prescribes VOC sampling and analytical
procedures and how to reduce interference from background contamination.
A tool for determining whether the VI pathway is complete. This guidance uses a
“multiple lines of evidence” approach to
identify the potential contaminant source,
including review of soil gas; sub-slab soil
gas; groundwater; crawlspace vapor and
indoor air data; background data; spatial
and temporal variations; soil geology; and
building design/construction, operation
and condition.
Sections include conceptual site model,
development of screening levels, investigative procedures, petroleum hydrocarbons and biodegradation, background
indoor air contamination, data interpretation, community outreach and remedial
action.
A practical how-to guideline for assessing
the VI pathway. This guidance describes
various tools available for investigation,
data evaluation and mitigation. It also addresses concerns from community stakeholders affected by VI cases, including
consideration of cumulative and synergistic risk from multiple contaminants, and
the requirement for indoor air sampling.
Defines a process for screening, investigating and mitigating vapor intrusion conditions in addition to a Phase 1 Environmental
Site Assessment for property transactions.
States that vapor intrusion should not
prevent redevelopment but that VI should
be considered early in the site planning
process in order to achieve pre-construction
cost savings.
