1. Taryn McKnight – Client Relations Manager
Vapor Intrusion: Improving Data Quality Using Today’s Guidance and Best Practices
Taryn McKnight – Client Relations Manager

2. Volatile chemicals from the subsurface intrude into overlying buildings.

3. Vapor Intrusion Timeline
EPA Adds Subsurface Intrusion to the Superfund Hazard Ranking System
2016
EPA OSWER finalizes Vapor Intrusion Guidance
2015
EPA OUST and ITRC work to publish Petroleum Vapor Intrusion Guidance
2014
OSWER works to finalize 2002 Draft Vapor Intrusion Guidance
2013
ASTM D Standard Practice Active Soil Gas
2011
ASTM E Standard Guide Vapor Encroachment
2010
ITRC Publishes Vapor Intrusion Guidance
2007
NY Re-opens 1400 NFR Sites
2006
OSWER replaces RCRA
2002
Redfield Rifle/CDOT
1998
J&E model
1991
1990
1995
2000
2005
2008
2012
2014
2015
2016
Many States Publish VI Guidance
2008 EPA Publishes Attenuation
Factor Database
States begin addressing Vapor Intrusion: MA, CT, CA
Many organizations are hard at work, updating and finalizing guidance and standards
2015
Final Guidance is published
2016
Addition of VI to HRS and current debate over short term TCE risk
Modified from: M. Traister, O’Brien & Gere

4. Final VI Guidance
FINALLY!

5. Note important updates to Indoor Air Testing
Page 15, Table 1-2
Note important updates to Indoor Air Testing

6. Key Recommendation Highlights
Limit analyses to chemicals of concern
Section 6.4
Assess the VI pathway using multiple lines of evidence
Sections 6.3, 7.1 & 7.2
Generally support the decision to collect indoor air data
Document objectives and methods in a VI workplan
Consider collecting multiple rounds of indoor air samples
Section & 6.4.1
Section 7.4
Section 6.2

7. Conceptual Site Model (CSM) & Data Quality Objectives (DQOs)
Considerations:
Site conditions & historical data
Compounds of concern & anticipated concentrations
Screening levels
Sampling protocols
Involve the lab early on
“A CSM integrates all lines of site-specific evidence into a three dimensional conceptualization of site conditions…” Section 2.0
Section 2.0
The CSM will help guide the DQOs
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8. Sources of Variability
Potential Sources of Variability in Measured Data Barometric pressure Surface cover Preferential pathways Soil moisture & permeability Building depressurization Seasonal effects: Advection Biodegradation Background air
ITRC 2007

9. Vapor Intrusion: Impacts to Data
Stack Effect
Barometric Pressure Changes
Wind Effect
Vapor Transport:
Concentration Pressure & Temperature gradient
Indoor sources: carpet, dry cleaning, air fresheners, glues, paint, solvents, smoke, cleaning supplies, heating oil
Other sources: Vapor Intrusion, Ambient Air Intrusion
Vapors In/Out
Ambient
Background
Breathing Zone
HVAC
Lithology
Preferential Pathways
Vapors in
Soil moisture content
Vapors out
Water Table
Vadose Zone
Contaminated Groundwater
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10. Multiple Lines of Evidence
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11. “A potential shortcoming of indoor air is background”
Indoor Air Sampling
Pros
Actual concentration, no modeling, no attenuation
Relatively quick, no drilling
Less spatial variability than subsurface
Cons
Working with the “Homeowner”
Access agreements, factsheets, meetings
Requires removal of interior or lifestyle sources
Contribution from unknown indoor sources
Per EPA: Collect indoor samples and compare with controls: sub slab, ambient, lines of sight evidence
Section 6.4.1
“A potential shortcoming of indoor air is background”
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12. “A potential shortcoming of indoor air is background”
Indoor Air: Active or Passive
Active Sampling Considerations
CoCs
Screening Levels
Litigious site?
Passive Sampling Considerations
Desire for long term monitoring
Environmental conditions
Target analyte list and RLs
Per EPA - Collect indoor samples and compare with controls:
Sub slab, ambient, lines of sight and building evidence
Passive samplers “their use may grow…”
Section 6.4.1
“A potential shortcoming of indoor air is background”
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13. Background Contamination
Common Household Contaminants
Acetone
Formaldehyde
Benzene
n-Heptane
Bromomethane
n- Hexane
2-Butanone (MEK)
Methylene chloride
Chlorobenzene
Methyl isobutyl ketone
Chloroethane
Methyl tert butyl ether
Chloroform
Styrene
Cyclohexane
1,1,2,2-Tetrachloroethane
1,4-Dichlorobenzene
Tetrachloroethene (PCE)
Dichlorodifluoromethane
Toluene
1,1-Dichloroethane
1,1,1-Trichloroethane
1,3-Dichloropropene
Trichloroethene (TCE)
Ethylbenzene
Xylenes, total
Source: NJDEP
Consumer Activities
Household Products
Building Materials
Outdoor Air
Section Identify & Evaluate Contributions from Indoor & Ambient Sources
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14. Sub Slab Sampling Pros Can resolve indoor sources
Can assess if the VI pathway is complete
Can be used to assess the potential for VI risk
Cons
Method is intrusive
Requires access agreements
Substantial spatial variability under the slab
Per EPA: Collect multiple samples to address spatial variability and multiple rounds to address temporal variability
Section “There may be substantial spatial variability in sub-slab soil gas”
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15. Soil Gas Sampling Pros Provides an estimate of vapor concentrations
Can be performed without entering the structure
Cons
Significant spatial variability
May not be representative of vapor concentrations under buildings
Per EPA: “Several rounds of sampling are generally recommended, particularly…”
Section “individual exterior soil gas samples cannot generally be expected to accurately estimate sub-slab or indoor air concentrations”
Modified from: Rick Ehrhart, RCRA Corrective Action, EPA Region 6
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16. Soil Gas/Sub Slab Sampling Guidance
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17. Soil Gas Sampling Protocols
Purge tubing
Using a syringe, bag or canister
Flow rate for purging/collecting <200mls/min
Using a flow controller
Apply a tracer gas (e.g. helium, Freon or IPA)
Measure for biodegradation at petroleum sites
Test for CH4, O2 and CO2
Using a shroud, a field detector and a tracer gas
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18. Leak Check Considerations
Liquid (qualitative) or Vapor (quantitative)
Shroud
Field or Laboratory analysis
Reporting limit requirements
Estimated values exceed the calibration range
Section “a reliable seal of the annulus between the probe and the probe housing and leak testing for the seal are generally recommended”

19. Real World Shrouds

20. Shut-in Leak Test Remove brass plug Loosen FC fitting
Attached FC to Can
Finger tighten
¼ turn with wrench
Attach brass plug to FC
Tighten with wrench
Open and close valve
Observe gauge reading

21. “T-fitting” or “Co-locator”
Field Quality Control Samples
Field Duplicates
Requires the use of a
“T-fitting” or “Co-locator”

22. Media Certification and Management
Segregated for cleaning
Low level (ambient & indoor)
Source level (soil gas)
Cleaning
Evacuated, heated, flushed
Certification
Batch or individual
Overnight leak check test

23. Gauges, Impact to Data? Field Sampling Media
Initial Vacuum – sufficient vacuum
Range will be 25-30”Hg
Final Vacuum – sufficient sample
Range should generally be 10-0”Hg
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24. Shipping, Preservation and Holding Times
Section “Fourteen days is the most commonly cited hold time for air samples in canisters”
Canisters
No preservation required
Can be shipped by air with few caveats
Hold time specified in TO-15 is 30 days

25. EPA Indoor Air Screening Levels
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26. Target Analyte Lists - Volatile?
The primary focus of Vapor Intrusion = Volatiles
Not everyone agrees what constitutes a VOC
SVOCs
Metals
Pesticides/PCBs
Require sorbent/filter methods TO-13A, TO-10A, 6010

27. U.S. EPA VISL Calculator From the new guidance:
6.5.2 EPA developed VISLs for human health protection that are generally recommended, medium-specific, risk-based screening-level concentrations…
These VISLs calculated are based on:
• Current toxicity values (OSWER’s EPA 2003).
• Physical-chemical parameters for vapor-forming chemicals
• EPA-recommended approaches for HHRA (EPA 2009c, 2014a)

28. Screening Levels – What Questions to Ask
State or Federal? Soil gas or Indoor air? Residential/Commercial attenuation factor? Units? Target analyte list?
EPA RSLs or State Limits Do limits exist for your matrix If not, how will you calculate for them? Be careful of units! Will you limit the list and does it include non-volatiles?

29. Commonly Requested Methods
VOCs: TO-15, TO-17
Hydrocarbons: TO-15, TO-3
Fixed Gases: ASTM D-1946
SVOCs: TO-13A
Diesel Range: TO-17
Carbon Range Speciation: MA APH

30. EPA Method TO-15
FAQs:
EPA Method TO-15 was written for the determination of VOCs in ambient air collected in specially-prepared canisters and analyzed by GC/MS at concentrations above 0.5 ppbv.
Method TO-15 is appropriately applied to only a subset of the 97 Title III VOCs, therefore a standard TO-15 list was not established.
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31. SIM vs. Full Scan
“SIM” Selected Ion Monitoring – the process by which the instrument method is limited to detecting selected ions
Full Scan Spectra
SIM Spectra

32. Summary
Do not take samples unless you have some idea of what the data is going to tell you - Conceptual Site Model Define your data quality objectives up front, this will determine the appropriate containers, collection procedures and analyses Teamwork with your laboratory up front will ensure less questions when you receive the data Data quality is a function of the whole process: the project set up, the field sampling protocols, and the analytical protocols

33. Taryn McKnight taryn.mcknight@testamericainc.com
Questions?
Taryn McKnight