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Intrusion Vapor
Intrusion Guidance Document
NJDEP Vapor Intrusion Guidance
The NJDEP has finalized the Vapor Intrusion Guidance (October
2005) document to provide assistance in the evaluation of contaminated
sites. The document has been modified after consideration of the latest
state of the science and comments received on the draft document after
it was placed on the web site for external review in June 2005.
The document consists of a phased approach to investigate the vapor intrusion
(VI) pathway that follows the basic provisions of the USEPA Draft Vapor
Intrusion Guidance, while incorporating New Jersey specific factors/policies,
when appropriate. The guidance includes a discussion of the VI pathway,
VI screening levels to be used in the evaluation of a site, sampling and
analytical requirements, site-specific screening options, remedial options,
monitoring and maintenance requirements, community outreach, and a methodology
to evaluate background air concentrations.
The following revisions to the draft (June 2005) document have been incorporated
into the NJDEP Vapor Intrusion Guidance (October 2005).
- The attenuation factor used in the development of the Soil Gas Screening
Levels (SGSL) has been decreased from 0.05 (20 times the health-based
indoor air value) to 0.02 (50 times the health-based indoor air value)
to reflect the latest science. (see Sections 4.4 and Appendix G)
- The Immediate Environmental Concern Indoor Air Action Levels (IECIAAL)
have been renamed the Rapid Action Levels (RAL) and defined as trigger
levels for the initiation of a prompt action at occupied buildings to
investigate and/or remediate the VI pathway. The RAL are not applicable
to nonresidential facilities currently handling VI related chemicals
subject to OSHA regulations. (see Section 4.3.3)
- By policy, the RAL for trichloroethylene (TCE) has been changed to
the TCE Health Department Notification Level noted below. (see Section
4.3.3)
- Health Department Notification Levels (HDNL) developed in cooperation
with the NJDHSS has been included in the document for thirteen of the
main VI contaminants of concern. (see Section 4.3.3)
- A Remedial Decision Matrix has been added to the Decision Flow Chart
to better clarify the remedial action assessment in regard to the relationship
between sub-slab soil gas and indoor air data. (see Sections 7.7 and
Appendix A)
- The definition of a receptor has been clarified to include consideration
of uninhabited structures due to the potential for future use. Open
garages and limited access structures (small utility sheds) are considered
case by case. (see Section 2.3)
- Several ground water sampling recommendations have been modified
to provide greater clarity, more flexibility, and assist in site-specific
decision making. (see Section 6.2.3)
- Descriptions of two additional “exit ramps” for completing
a VI investigation have been added to the chapter on data evaluation
based on analyses of ground water and/or soil gas data. (see Sections
7.2 and 7.4)
- The document has been modified to indicate that while the initial
soil gas and indoor air sampling rounds are analyzed for the full suite
of volatile chemicals, subsequent phases can employ a reduced list of
parameters as part of an approved VI investigation work plan. (see Section
6.3.2.4 for soil gas)
Due to routine updates to the screening level tables, it is recommended
that the user refer to the NJDEP Vapor Intrusion web site at http://www.nj.gov/dep/srp/guidance/vaporintrusion/
for the latest information. A notice will be placed on the web site to
indicate future changes to this guidance.
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28 March 2007
ZIP
of the PDFs of the VI Guidance Document and its Tables