Vapor Intrusion, or VI, is a very dynamic topic as it relates to environmental assessments. This is a very brief VI update Dragun provided to attorneys in Michigan in February 2017. Keep in mind the rapidly-changing nature of VI standards as you review this February 2017 PowerPoint.
Understanding Air Quality Monitoring A Comprehensive Guide.pdf
February 2017 Vapor Intrusion Update Oakland County Bar Association
1. Vapor Intrusion (VI)
What is it and why should I care?
February 23, 2017
Farmington Hills, MI | Windsor, ON | Toronto, ON
Matthew Schroeder, PE and Jeffrey Bolin, CHMM
2. What is Vapor Intrusion?
Vapor Intrusion (VI)
Conceptual Site
Model
3. Why Should We Care?
Text
10 years ago VI was not typically evaluated in RIs
Now VI concerns are often a driver for investigations and
remediations
Included in ASTM Phase I standard
Recently added to Superfund scoring*
5. Why Should We Care?
My site is closed!
• We all heard MDEQ say “A deal is a deal”
but…
6. Why Should We Care?
VI is regulated differently depending on location, and
the guidance is changing rapidly
• USEPA guidance (2015)
• State guidance (Michigan,
Ohio, Indiana, and Illinois all
revised/issued guidance
within the last year)
• California, Massachusetts
incorporating new science
quickly (maybe before
proven?)
7. Why Should We Care?
VI is regulated differently depending on location, and
the guidance is changing rapidly
• Inconsistency across jurisdictions on what
data is needed and what criteria apply
• Very conservative assumptions used to
calculate screening levels
• Difficult to off-ramp once you exceed a
screening level
Soil and groundwater?
Sub-slab vapor?
Indoor air?
Models?
Attenuation factors?
OSHA criteria?
Criteria
8. Michigan’s Draft Rules (VI)
• Issued in June 2016, revised in October 2016
• Tiered approach to VI assessments
• Tier 1 – Initial Screening Levels
• Tier 2 – Generic Criteria (incorporate soil type, depth to groundwater)
• Tier 3A – Generic Criteria (Use Facility-Specific Land Use & Building Specifications)
• Tier 3B – Site Specific Data
• Vapor Intrusion Calculator Tool (under development)
• Generally tries to avoid Indoor Air Testing
10. The Perfect Storm
TCE and Vapor Intrusion
• TCE short-term exposure limits
• Reliability of science doesn’t seem to
matter
• Response actions required within days
• Michigan using Department of Health
and Human Services to circumvent
process and force evacuations until
response actions conducted
Image from NBC
11. How do I determine if VI is an
issue at my site?
• Soil and groundwater data
• Subsurface soil gas
• Sub-slab soil gas
• Indoor air
12. What’s on the horizon (or closer)?
• Overcoming sampling variability
• Passive, long duration indoor air sampling
• Large volume sub-slab sampling
• Isotope analyses to differentiate sources
• Handheld GC to identify sources to indoor air
13. Takeaways
• Vapor intrusion assessment is changing rapidly,
in the science, regulations, and public awareness
• More so than ever before, vapor intrusion is the
driver for remediation/mitigation actions
• Vapor intrusion concerns can kill deals, cause
evacuations, and lead to litigation liability
EPA: “Vapor intrusion is the general term given to migration of hazardous vapors from any subsurface vapor source, such as contaminated soil or groundwater, through the soil and into an overlying building or structure.”
Fuels (benzene, in particular)
Solvents (TCE, TCA, CT)
Dry cleaning chemicals (PCE and its breakdown products)
Landfill gas (methane)
If VI was evaluated, it was done using soil and groundwater data
Relatively high screening levels
A few high profile incidents where VI became a widespread issue despite gw concentrations “passing”
Much higher awareness of VI considerations among regulators (varying levels of technical understanding)
Potential for third party litigation (class action)
Discuss Storage Mart project – did not consider CVOCs in due diligence, seven figure remediation driven by VI concerns (owner going after consultant)
*Trump administration put this on hold until further review is completed
Public awareness (VI in the news)
Last one – right in our own backyard
If the Superfund scoring change passes, many sites could get added to the Superfund list
Some States (MA, MN, NY) reopening closed sites
Michigan – 4,000 orphaned sites with potential VI issues
According to MDEQ, no plans to reopen “private” closed sites
Will sites reopen due to VI concerns during transactions or refinancing?
USEPA guidance – long time coming
State guidance – each one is different
With each guidance revision, screening levels seem to go down
Dense sampling networks and multiple sampling events needed to off-ramp
Higher level of data collection needed for higher tiers of assessment
Rules still in draft, but you should consider them when assessing sites (since MDEQ will be)
Focus on CSM – can off ramp from there
Facility designation – implications on transactions, due care obligations
We stole the slide title from an article by David Gillay of B&T
3 things coming together – focus on VI, new tox information on TCE, aggressive actions by regulatory agencies
USEPA Region 9 began enforcing mitigation actions based on potential short-term exposure to first-trimester pregnant women
Based on a single 22-day study on female rats that has not been successfully replicated
Reference DHHS memo re GR sites
Summa canister – traditionally 24 hours, new thinking – IA = 8-10 hours (work shift), SS = 200 mL/min (30 min for 6L canister)
Why not just collect IA samples?
Data interferences with IA sampling
Some criteria near background (TCE, benzene)
Paired IA + SS samples
TO-17 (sorbent tubes) – captures both VOCs and SVOCs, less sampling time, 1/3 rental cost, not yet widely accepted (not included in USEPA or MI guidance, although MI accepting on case by case basis)
All these techniques are available, but not widely used
Research indicates indoor air concentrations are variable temporally, sub-slab vapor concentrations are variable spatially
