Haley & Aldrich, Inc.
Vapor Intrusion Regulatory
Updates
22 April 2013
Presented by Richard J. Rago, Vapor Intrusion Practice Leader
Haley & Aldrich, Inc.
Agenda
• Vapor Intrusion Basics
• Vapor Intrusion Pathway Evaluation by Various State Programs
• OSWER Final Guidance For Assessing And Mitigating The
Vapor Intrusion Pathway From Subsurface Sources To Indoor
Air (April 2013 External Review Draft)
• OUST Guidance For Addressing Petroleum Vapor Intrusion At
Leaking Underground Storage Tank Sites (April 2013 External
Review Draft)
• New Indoor Air Background Study in Massachusetts
• Considerations for practitioners
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VI Pathway: Main Transport Mechanisms
• Diffusion of vapors from sources in the unsaturated zone
• Diffusion of vapors from sources in shallow ground water
• Advective/convective transport of vapors
• Vapor migration through preferential pathways
Key Point: Understanding soil and groundwater is prerequisite to
developing a VI CSM and developing a sampling strategy
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General Approaches to Assessing
Vapor Intrusion
• EPA and many states use a tiered approach to
evaluate sites:
• Tier 1 – Simple Screen
• Are VOCs present?
• Tier 2 – Simple screen
• Are VOCs above de minimis levels?
• Tier 3 – Site-specific evaluation
Key Point: For the VI pathway to be complete, there must be a source, a
mechanism for transporting contamination, and a potential receptor.
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1992.. 1996 1997 1998.. 2000 2001 2002.. 2004 2005 2006 2007 2008 2009
MassDEP
Numerical
Standards
NYS DOH
IA Background
Study
CT DEP
Numerical
Standards
CDPHE
Redfields,
CDOT Sites
MDEQ
Volatilization
Criteria
(RBSLs)
NH DES
Standards
NYSDEC
Endicott, NY
VI Project
OSWER (EPA)
MassDEP
IA Sampling
Guide & Proposed
Revisions
MDEQ
Revisions
MDEQ
TCE memo
and RRD Op
Memo No. 1
NYS DEC
Draft Policy
CA DTSC
VI Guidance
NH DES
Residential
IA Assessment
Guide
CDPHE
IA Analysis
Guide
Michigan Science
Board Evaluation
NYS DOH
IA Sampling
Guide
IDEM
NYSDOH
NHDES
ITRC
MassDEP
Internal SOP
UPVs
ASTM
EPA
Mitigation
Advisory
MDEQ
RRD Op
Memo No. 4
OSWER TCE
Memo
CTDEP
SVS SOP
CA DTSC
VIMA
SG
Advisory
NJDEP
History of VI Guidance Development
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1992.. 1996 1997 1998.. 2000 2001 2002.. 2004 2005 2006 2007 2008 2009
MassDEP
Numerical
Standards
NYS DOH
IA Background
Study
CT DEP
Numerical
Standards
CDPHE
Redfields,
CDOT Sites
MDEQ
Volatilization
Criteria
(RBSLs)
NH DES
Standards
NYSDEC
Endicott, NY
VI Project
OSWER (EPA)
MassDEP
IA Sampling
Guide & Proposed
Revisions
MDEQ
Revisions
MDEQ
TCE memo
and RRD Op
Memo No. 1
NYS DEC
Draft Policy
CA DTSC
VI Guidance
NH DES
Residential
IA Assessment
Guide
CDPHE
IA Analysis
Guide
Michigan Science
Board Evaluation
NYS DOH
IA Sampling
Guide
IDEM
NYSDOH
NHDES
ITRC
MassDEP
Internal SOP
UPVs
ASTM
EPA
Mitigation
Advisory
MDEQ
RRD Op
Memo No. 4
OSWER TCE
Memo
CTDEP
SVS SOP
CA DTSC
VIMA
SG
Advisory
NJDEP
History of VI Guidance Development First Established/Discussed
Different Triggers for PHC
Not a lot happening
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Recent VI Updates Provide For
Challenging Regulatory Landscape
• 6 guidance documents released or updated in 2010
• 7 guidance documents released or updated in 2011
• ~25 guidance documents released or updated since 2010
• 3 from New Jersey in the past fifteen months
• 4 from EPA in past five months
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Only fourteen states remain without VI Guidance
(Many are recent; Alaska and Hawaii have VI Guidance)
States with VI Guidance
States without VI Guidance
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Basic Differences Between States
• Trigger Distances
• Petroleum Hydrocarbons: a few <30 ft, some 30-50 ft, many still 100 ft
• CVOCs: a few <100 ft or >100 ft, nearly all 100 ft
• Screening Levels
• GW, Soil, Deep Soil Gas, Shallow Soil Gas/Sub-slab, Indoor Air
• VI Screening Levels (can differ over orders of magnitude)
• Attenuation Factors
• Groundwater (H): often 0.001
• Crawlspaces: often 1
• NJ shallow soil gas: 0.02, some 0.001, some 0.1
Eklund et al, 2013
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16 April 2013 e-announcement, emphasis
added
• “EPA is affording the public with an opportunity to provide input on its draft final vapor intrusion guidance documents. This afternoon, the Office of Solid Waste and Emergency Response released for public input two draft vapor intrusion guidance documents: a general guidance for all compounds; and one focused on petroleum hydrocarbons released from underground storage tanks. When final, these guidance documents will help ensure vapor intrusion exposure assessment and mitigation actions to protect human health are undertaken in a technically, scientifically and nationally consistent manner. The documents can be accessed at:” http://www.epa.gov/oswer/vaporintrusion.
• Public input must be submitted by May 24, 2013, at: http://www.regulations.gov; docket number: EPA-HQ-RCRA-2002-0033-007.
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OSWER VAPOR INTRUSION GUIDANCE
• OSWER Final Guidance For Assessing And Mitigating
The Vapor Intrusion Pathway From Subsurface Sources
To Indoor Air
• November 2012 Draft Internal EPA Deliberative Document
obtained by InsideEPA.com
• April 2013 External Review Draft
• Not prescriptive like the 2002 guidance
• allows room for interpretation and professional judgment in
reaching conclusions about VI
• Flexible with no Tier I/Tier II/ Tier III screening
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Elements of 2013 OSWER Draft
• Definition: “Vapor intrusion is similar to radon intrusion…”
• Statutory authority: “Protection of human health is a critical
mandate underlying several federal statutes, including …”
“On this basis, the EPA has broad authority to assess and,
if warranted, mitigate vapor intrusion in residential and
nonresidential settings…”
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2013 OSWER Scope/Applicability
• “EPA recommends consideration of the Final VI Guidance when: Making
“Current Human Exposures Under Control” environmental indicator (EI)
determinations at RCRA corrective action facilities (EPA 1999a, 2002b)10 and
National Priorities List (NPL) sites under CERCLA (EPA 2008b); Undertaking
removal actions, remedial actions, pre-remedial investigations,11 remedial
investigations, and five-year reviews (FYRs)12 under CERCLA; and
Undertaking RCRA facility investigations and corrective actions and site
investigations and cleanups at federal facilities and brownfield sites.”
• “The broad concepts of this guidance generally may be appropriate when
evaluating any of a large number and broad range of vapor-forming
chemicals…”
• “chlorinated hydrocarbons (CHCs), petroleum hydrocarbons, other types of both halogenated
and non-halogenated volatile organic compounds (VOCs), elemental mercury, and radon when
it arises from uranium-or radium-bearing solid wastes in the subsurface.”
• Also includes methane references, if from natural gas transmission lines
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General OSWER Approach
Considerations
• Not much of a departure from what skilled VI practitioners are already doing for risk-based pathway screening
• Establish the Conceptual Site Model (CSM) for VI
• Choose applicable Vapor Intrusion Screening Levels (VISL)
• If source medium is NAPL or unsaturated soil, then use soil gas data
• Deep soil gas data are applicable for characterizing VI and are interpreted as being representative of sub-slab conditions
• Can use modeling to support no significant VI pathway with other MLEs; most applicable to cases of future building construction
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OSWER Conceptual Site Model Language
• Three conditions must exist for hazardous vapors to reach
the interior of buildings from the subsurface environment
underneath or near a building:
• A source of hazardous vapors must be present in the soil or in
groundwater underneath or near a building
• Vapors must form and have a pathway along which to migrate
toward the building
• Entry routes must exist for the vapors to enter the building and
driving forces must exist to draw the vapors into the building
• If these three conditions are present, the vapor intrusion
pathway is referred to as “complete”
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OSWER Contaminants of Potential
Concern
• a chemical is considered to be “vapor-forming” if:
• molecular weight less than 200 grams per mole, vapor pressure greater than 1 milliliter of mercury, or Henry’s law constant greater than 10-5 atmosphere-meter cubed per mole; and;
• vapor concentration of the pure component exceeds 33 times the indoor air target risk level if the vapor source is in soil, or, if in groundwater, the saturated vapor concentration exceeds 1,000 times the target indoor air risk level
• “EPA recommends that these chemicals be routinely evaluated during vapor intrusion assessments conducted in accordance with the Final VI Guidance, when they are present as subsurface contaminants.”
• List includes Biphenyl, Aroclor 1221, Aroclor 1232, Naphthalene, Cyanide (CN- and HCN), Mercury
~Inverse of recommended alphas used
~Acenaphthene, Anthracene, Fluorene, 1-Methylnaphthalene, 2‐Methylnaphthalene, Pyrene, other CNs removed
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OSWER Prompt Action Conditions
• Explosive conditions (one-tenth (10%) of the lower explosive limit)
• When measured concentrations exceed sub-chronic or acute toxicity values (e.g., sub-chronic inhalation reference concentrations) or regional removal management levels
• Odors reported by occupants, particularly if described as “chemical,” “solvent,” or “gasoline”
• Physiological effects reported by occupants
• Wet basements in areas where groundwater is known to contain vapor-forming chemicals
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OSWER Preliminary Analysis of VI
• Two conditions, at a minimum, must be present for the VI
pathway to pose a potential human health threat
• there must be a source of vapor-forming chemicals in the
subsurface environment
• includes reference to a “primary vapor release such as from
natural gas transmission lines”
• buildings are present (or could be constructed in the future) above
or “near” the subsurface vapor source(s)
• “building” refers to a structure that is regularly occupied and
used by humans
or could be occupied and used in the future
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OSWER Conceptual Site Model
Considerations
• “In general, CSMs identify the potentially exposed
populations, potential exposure routes, and potential
adverse health effects (i.e., toxicity) arising from indoor air
exposures. Therefore, the CSM also should identify and
consider sensitive populations, including but not limited to:”
• Elderly
• Women of child-bearing age
• Infants and children
• People suffering from chronic illness
• Disadvantaged populations (i.e., an environmental justice situation)”
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OSWER Action Levels and Alphas
• New: “Where the aggregated carcinogenic risk to an individual based upon a reasonable maximum exposure condition for both current and future land use is less than one per ten thousand (i.e., 10-4 or one hundred per million) and the noncancer HI is less than 1, response action is generally not warranted for vapor intrusion.”
• The risk range upper boundary not a “bright line” at 10-4, and arisk estimate that is “around 10-4” may be acceptable if justified. Risk managers may also decide that risk levels less than 10-4 are unacceptable for site-specific reasons and require response actions for VI.
• Alphas:
• Groundwater = 0.001 (0.0005: semi-site-specific value for fine-grained vadose zone soils)
• sub-slab and exterior soil gas = 0.03
• crawl space =1
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OSWER Investigation Considerations
• Buildings within 100 feet laterally of subsurface vapor sources
(or 100 feet vertically of underlying vapor sources) should be
considered “near” for VI investigations, assuming preferential
pathways are not present
• A “worst first” (e.g. “step out”) approach is recommended to
investigating buildings
• Allows for groundwater, soil, soil gas sampling (including
“exterior soil gas”), and crawl space air sampling
• EPA recommends exterior soil gas sampling at various depths or
several depth intervals
• Include a “near-source” soil gas sample collected immediately above
each source of contamination to help characterize the vapor source
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OSWER Sampling and Risk Management
Framework
• Multiple sampling rounds recommended
• When the VI pathway determined to be incomplete, then
mitigation not generally warranted under current
conditions
• EPA recommends that site managers also evaluate whether
subsurface vapor sources that remain have the potential to pose
unacceptable VI health risks in the future if site conditions were to
change
• Response actions may be warranted to protect human health
wherever and as long as subsurface vapor sources remain that
have the potential to pose unacceptable health risks in the future
due to VI
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EPA Petroleum Vapor Intrusion (PVI)
Guidance
• Guidance For Addressing Petroleum Vapor Intrusion At
Leaking Underground Storage Tank Sites
• November 2012 EPA Office of Underground Storage Tanks;
Redline Strikeout Draft document obtained by InsideEPA.com
• April 2013 EPA OUST External Review Draft
• “…PVI guidance focuses on underground storage tanks,
typically located at gas stations and non-marketing
facilities regulated under Subtitle I of the Solid Waste
Disposal Act.”
• Increased flexibility
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PVI Document Has Narrow Focus
• PVI associated with three classes of chemicals:
• PHCs found in gasoline, diesel, and jet fuel (e.g., benzene,
trimethylbenzenes)
• Other vapor-forming chemicals found in petroleum (e.g., methyl
tertiary-butyl ether (MTBE) and other fuel additives)
• Methane from anaerobic biodegradation of PHCs and other
constituents of petroleum fuels, especially ethanol
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OUST PVI Document: PVI Unlikely
• Indicates that few confirmed occurrences of PVI at
petroleum sites are reported in literature
• Adds references that there are no reported cases of vapor
intrusion from dissolved-phase petroleum hydrocarbon
sources vertically separated from building foundations
• Suggests that most likely scenarios for PVI to occur are
shallow PHC sources directly beneath buildings and
mobile LNAPL or groundwater plumes with high
concentrations of PHCs in direct contact with buildings
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PVI Document Lateral Exclusion Distance
• Determine Whether Further Investigation Is Unnecessary:
• EPA references that a vertical separation distance of 5.4 feet from
dissolved sources and 13.5 feet for LNAPL sources adequate to
eliminate the potential for PVI
• Because of the difficulty in accurately measuring precise
distances, EPA recommends vertical separation distances of 6 feet
for dissolved and 15 feet for LNAPL sources
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OUST: Further investigation for PVI may
be unnecessary:
• low levels of soil contamination (clean soil; i.e., LNAPL is
not present as mobile or residual material) or groundwater
contamination:
• Groundwater ≤ 30 mg/L TPH (gasoline) or benzene ≤ 5 mg/L or
soil ≤ 250 mg/kg TPH (gasoline) or benzene ≤ 10 mg/kg, and
vertical separation distance between PHC and the lowest point of
a building foundation, basement, or slab is 6 feet or more
• high levels of soil or groundwater contamination (i.e.,
LNAPL is present):
• groundwater > 30 mg/L TPH (gasoline) or benzene > 5 mg/L or
soil > 250 mg/kg TPH (gasoline) or > 10 mg/kg benzene, and the
vertical separation distance between PHC and the lowest point of
a building foundation, basement, or slab is greater than 15 feet
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PVI Document: Biodegradation
• At short distances from source, PHCs become negligible
primarily due to aerobic biodegradation; literature reported
that PHCs vapors from dissolved plume were almost
completely degraded within 1 meter above the water table
and that transport of PHC vapors may only be significant if
the source is LNAPL
• For large buildings and/or where there is extensive
impermeable surface covering, soil vapor samples
recommended if concern that conditions may impede flux
of oxygen to subsurface and create an oxygen shadow
• oxygen content should be > 1% throughout thickness of
clean, biologically active soil for aerobic biodegradation
Massachusetts Study of Indoor Air
Background VOCs and APH in
Schools, Offices, and Municipal
Buildings
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Benzene Residential TV: 2.3 ug/m3
Median: 1.6 ug/m3 Median: 1.8 ug/m3
Residential background data
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New Massachusetts Indoor Air
Background Study
• Focused on Commercial/Municipal Offices and Schools
• Designed with input from MassDEP and EPA
• Conducted by Haley & Aldrich, Alpha Analytical, SKC, and
eurofins/Air Toxics LTD
• Acknowledgements to Andy Rezendes, Linda Coyne, and Heidi
Hayes
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New Massachusetts Indoor Air
Background Study (continued)
• Sampling in winter using Summa canisters with 24-hour
flow controllers
• Analysis via TO-15 (full scan and SIM) and MassDEP CAM APH
• Side by side sampling using SKC Ultra III Passive
Samplers
• Analysis via TO-17
• Initial round of sampling completed
• 10 samples collected in schools
• 10 samples collected in offices
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New Massachusetts Indoor Air
Background Study – preliminary results
• Tetrachloroethylene detected in 100% of office samples and
60% of school samples
• Concentrations ranging from 0.136 ug/m3 to 9.02 ug/m3
• Benzene detected in 100% of office samples and 100% of
school samples
• Concentrations ranging from 0.319 ug/m3 to 24.8 ug/m3
• Trichloroethylene detected in 1 office sample at 0.441
ug/m3
• 1,2-dichloroethane detected in 90% of office samples and
60% of school samples
• Concentrations ranging from 0.085 ug/m3 to 0.498 ug/m3
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Possible Implications of Federal Changes
and Updates
• EPA guidance documents may result in greater
inconsistency
• Potentially unreasonable standard of care expectations
• States may follow suit and allow increased or decreased
flexibility
• PRP sites may be grouped with the OSWER or OUST
document (or both)
• States may consider more conservative trigger distances
for PHCs
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Closing
• Please review the draft EPA OSWER VI and draft EPA OUST
PVI documents
• http://www.epa.gov/oswer/vaporintrusion/documents/vaporIntrusion-final-
guidance-20130411-reviewdraft.pdf
• http://www.epa.gov/oust/cat/pvi/petroleum-vapor-intrusion-review-draft-
04092013.pdf
• Public input must be submitted by May 24, 2013
• Please provide comments on the documents or request an extension at
http://www.regulations.gov; docket number EPA-HQ-RCRA-2002-0033-007
• http://www.regulations.gov/#!submitComment;D=EPA-HQ-RCRA-2002-0033-
0090
• Please consider your office building for the indoor air
background study
• http://www.haleyaldrich.com/downloads/rago_viupdates.pdf
Haley & Aldrich, Inc.
Thank You!
Richard Rago
Vapor Intrusion Practice Leader
Haley & Aldrich, Inc.
860.290.3115 tel.
617.719.6128 cell [email protected]
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