Vapor Intrusion Guidelines Becoming More Conservative?

In a recent letter (dated December 3, 2013) to the San Francisco Bay Regional Water Quality Control Board (Regional Water Board), the US Environmental Protection Agency (EPA) Region 9 offered guidelines and supplemental information for vapor intrusion (VI) evaluations.  The Regional Water Board was evaluating Superfund sites in the South San Francisco Bay Area (South Bay Sites) where trichloroethene (TCE) or tetrachloroethene (PCE) are contaminants of potential concern.

As history has shown us, when the environmental community in California catches a cold, the rest of the environmental communities in the US and Canada sneeze!  In this letter, the EPA recommends incorporating into existing and future VI evaluation work plans a number of activities that would make VI investigations more labor intensive and consequently more costly.  While the concern about “reopeners” for closed sites is intriguing, we’ll leave that for a future blog entry.

As to the guidelines/recommendations, they include:

  • Identifying women of reproductive age as the sensitive population of concern.
  • Using a “Short-Term Prompt Response Action Level” of 2 µg/m3 in residential settings.
  • Implementing interim measures to mitigate TCE short-term exposure by:
    • Increasing building pressurization and/or ventilation.
    • Installing and operating engineered, sub-floor exposure controls (sub-slab and/or crawlspace depressurization; or in some cases a soil vapor extraction system).
    • Eliminating exposure by temporary relocation.
    • Collecting an additional round of sampling in the colder weather months since the highest indoor air concentrations usually occur when outdoor air temperatures are significantly lower than indoor air temperatures.
    • Sampling in commercial buildings with HVAC-off.  Sampling duration should begin a minimum of 36 hours following shut-down of the building ventilation systems.
    • Buildings that were thought to have a low potential for VI (presence of a sub-floor vapor barrier for example) need to be evaluated and sampled for VI.
    • Any proposal to exclude particular off-property buildings from indoor air sampling must be supported by a robust, site- and building-specific multiple-lines-of-evidence analysis.

Some Questions

  • Will these conservative criteria in EPA Region 9 be adopted elsewhere?
  • Although “guidance” is not enforceable, will regulators consider these guidelines as “law”?
  • Does this suggest that we might see more “reopeners” of closed sites based on these VI recommendations?

We don’t necessarily have the answer to these questions.  But whether you are in EPA Region 9 or elsewhere, when it comes to VI, a measured, thoughtful and scientific approach should help you avoid chasing protracted and costly vapor investigations.

Thanks to Dr. Khaled Chekiri ( and Jeffrey Bolin, M.S., CHMM ( who authored this blog entry.  You can reach both Khaled and Jeff at 248-932-0228.


Vapor Intrusion Update


Vapor Intrusion Diagram: USEPA

Vapor intrusion, or Vapour intrusion (VI) if you prefer, is one of the “hot topics” in the environmental world.  While I was attending RemTec in Denver this past March, it was one of the tracks of discussion and dominated many of the conversations.

So what exactly is VI and why should you care?  I asked one of our VI experts, Dr. Khaled Chekiri, to provide some insight on VI.

What is VI, and what is the “scientific concern”?

Dr. Chekiri:  Vapor intrusion (VI) is the phenomenon by which volatile chemicals in soil or groundwater migrate from the subsurface into the air space of a building.  Understanding VI is important because of the potential impact on our health and safety.  Health concerns are considerable, because toxic chemicals often enter the bloodstream more easily through inhalation than other exposure pathways, like ingestion or dermal contact.

What are the questions or concerns surrounding VI?

Dr. Chekiri:  There are several, the main one being the confusion surrounding it.  The United States Environmental Protection Agency released the Draft VI rules in November 2002 (Draft OSWER Guidance for Evaluating the Vapor Intrusion to Indoor Air Pathway from Groundwater and Soil).  Since the November 2002 release, there has been wide disparity between various regulatory bodies (state and federal) and their approach to quantify VI.  For example, requirements and procedures to investigate VI (including sampling protocols), assessment of results, and how to mitigate VI are often inconsistent and ambiguous.  Further, many in the regulated community feel that they have been kept in the relative dark regarding what they should or shouldn’t do to assess VI risks on properties they may be purchasing.

What are the new developments?

Dr. Chekiri:  In April 2013, USEPA prepared external review draft documents of two guidance documents regarding vapor intrusion:

1)  A general guidance document for all compounds:  “OSWER Final Guidance For Assessing And Mitigating The Vapor Intrusion Pathway From Subsurface Sources To Indoor Air – External Review Draft” and

2)   A guidance document focused on petroleum hydrocarbons released from underground storage tanks:  “Guidance For Addressing Petroleum Vapor Intrusion At Leaking Underground Storage Tank Sites – External Review Draft.”

The idea is that these guidance documents will help to provide some consistency for investigative, as well as mitigation, methods as it relates to VI.  Whether they provide scientifically and technically sound approaches is yet to be determined.  And if you want to weigh in on this question, the deadline for public comment is June 24, 2013.

Is there anything new in Michigan as it relates to VI?

Dr. Chekiri:  In Michigan, the “Part 201/213 Vapor Intrusion Policy and Procedure” (the Policy) was revised and updated to include comments provided by stakeholders during the May 1 to August 1, 2012, comment period.  The Policy is currently under review by senior management at the Michigan Department of Environmental Quality (DEQ) and is expected to be completed soon.  Keep your eyes peeled!  A notice will be sent out on the DEQ listserv notifying interested parties of the newly-finalized document.

What should I do in the interim?

Dr. Chekiri:  First, if you are requested to test for vapor intrusion, we would continue to caution you to very carefully consider your options before moving forward with any sampling.  The science of VI is still relatively young.  However, legal issues surrounding environmental data are more mature, and once you have analytical results, you may have certain obligations that are best discussed with legal counsel.  There are (in my opinion) better approaches to assess the potential impact of vapors than just sampling.

Second, keep a watchful eye on the regulatory developments, especially if you are buying or selling properties that may be impacted by VI.  Real or perceived impact from VI could affect transactions and obligate a new owner to response actions under due care or continuing obligation rules.

And, of course, please call us at (248) 932-0228 or (519) 979-7300 with any questions you may have about VI or if you would like to discuss a peer review on a current investigation.

Frustrated with Environmental Remediation Efforts?

…then join us Thursday, October 25th (9 am to 11:30 am) at the Kellogg Center in East Lansing, Michigan for our next environmental remediation seminar. 

This is a fast-paced two-and-a-half hour seminar that will provide you with practical information. You will learn about site characterization and remediation with examples and case studies that show how proper characterization can save you money…in some cases BIG money.  For more information click here

If you are in the London, Ontario area, there is still time to sign up for the September 27th environmental remediation seminar

Vapor Intrusion: Update on EPA’s Actions

On April 12, 2012, one of my colleagues, Dr. Khaled Chekiri, attended the “USEPA and Region V States Vapor Intrusion Video Conference Roundtable.”  The Video Conference was hosted by Barnes & Thornburg, LLP in their Grand Rapids, MI office. 

Some of the issues discussed included:

  • Decision making criteria for ruling VI in/out
  • Screening levels for contaminants with no published inhalation toxicity criteria (e.g., cis-1,2-DCE, MTBE)
  • Methane accumulation underneath buildings resulting from bioremediation of chlorinated compounds
  • Standard method recommended by EPA (sampling, leak detection)
  • The role of sub-slab pressure tests, indoor air tests; frequency of testing; the need for long-term monitoring
  • Vapor movement through soils and VI conducted in wetter climates with various soil regimes
  • Sub-slab testing protocols for large buildings (commercial/industrial settings)
  • Coordination with OSHA
  • Guidelines for dry cleaners who no longer use PCE (pick-up/drop off)
  • Criteria for requiring  installation of mitigation systems in residential and commercial settings
  • Discussion of radon mitigation system applicability to vapor mitigation
  • Long-term operation, maintenance, and monitoring guidelines for mitigation systems
  • Passive and long-term sampling
  • Decision making criteria when a VI mitigation system is no longer needed
  • Post-mitigation testing regime for a building

The United States Environmental Protection Agency (USEPA) stated they are still committed to November 2012 for final Vapor Intrusion (VI) guidance.  The guidance will address changes in toxicity values for PCE and TCE, mitigation methods, vapors related to petroleum hydrocarbons, and acceptable institutional controls.

Finally, a document that provides a conceptual model scenario for the VI Pathway is available for free download at  The model may provide a “visual” help in determining the source location for various site conditions.  For example, the model shows that the distribution of petroleum compounds in soil gas can be very different from that of chlorinated compounds. 

This is just a brief overview of the four-hour conference.  If you have specific questions about VI, contact our Vice President of Technical Operations, Jeffrey Bolin, M.S., CHMM ( or Khaled Chekiri, Ph.D., P.E. ( at 248-932-0228.

Please note: we continue to caution our clients to very carefully consider options before moving forward with any sampling related to assessing the potential impact of vapors.

For an overview of VI, see our March 2011 article in ESE “Vapour intrusion from soil and groundwater: A challenge for property owners”

Is There an Environmental Regulatory “Onslaught”?

Kathleen Hartnett White, writing for the Texas Public Policy Foundation says, “The U.S. economy, struggling to find a path back to sustained growth, stands in the cross-hairs of the Environmental Protection Agency’s heavy-handed regulatory onslaught. EPA, under the Obama administration, is churning out new rules unprecedented in speed, number, scope, stringency and costs.”

Ms White, a Distinguished Senior Fellow-in-Residence and Director for the Armstrong Center for Energy and the Environment also writes, “Never in its 40-year history has EPA simultaneously promulgated so many major environmental rules characterized by converging effective dates, massive compliance costs, and mandates exceeding existing technological controls. Nor has EPA before relied on such speculative, manipulated science to justify this most aggressive regulatory agenda to date.”

 The 20-page paper provides a critique of 10 EPA rules

 1. Cross-State Air Pollution Rule (CSAPR);

2. Electric Utility Maximum Available Control Technology

Standards for Hazardous Air Pollutants (Utility MACT);

3. Industrial Boiler MACT;

4. Portland Cement Kiln MACT;

5. Cooling Water Intake Structure Rule (CWIS);

6. Coal Combustion Residuals Rule (CCR);

7. Ozone National Ambient Air Quality Standard (NAAQS);

8. Particulate Matter (PM) NAAQS;

9. Greenhouse Gas (GHG) Regulation of Stationary Sources;

10. GHG Regulation of Mobile Sources

The document can be found here

Soil and Groundwater Remediation Seminar Returns to Toronto Area

Essential Information You MUST Have BEFORE You Begin Soil/Groundwater Remediation.

If you missed our seminars in April and October 2011, don’t miss this next opportunity!

 “I was pleasantly surprised by the seminar. I usually attend this sort of thing with some degree of trepidation because it is usually 90% biased sales pitch wrapped in 10% useful information. Your seminar was almost 100% useful or potentially relevant. I wish I had seen it seven years ago, before we started our remediation.”

-A CEO who attended our Soil/Groundwater Remediation seminar

What’s worse than realizing you have to spend time and money on soil or groundwater remediation?  Spending the time and money and getting no closer to the end point!

There is no doubt that there are many proven remediation methods and many contractors who can execute these remediation technologies…but…this should NOT be your starting point!  Before you focus on solutions, make sure you clearly understand the problem and how the myriad of potential solutions apply to your specific situation.  That is where our seminar will prove valuable to anyone who is now, or in the future, tasked with site remediation.

We will spend two hours helping you understand the fundamentals of site characterization and remedy selection.  We will also discuss how to avoid common mistakes in site assessments and subsequent costly remediation.


  • The basics of site characterization: What factors control what happens to releases?
  • The fate and transport of releases in the subsurface: What’s with LNAPLs, DNAPLs, sinkers, floaters, retardation, etc.?
  • Basics of site remediation: What is best for my site?
  • How to reduce groundwater remediation efforts and expense
  • Site remediation options
  • How changes in O.Reg 511 affect site activities
  • Mini-Case Studies

Senior Dragun associates, Dr. Michael Sklash, P.Eng. and Matthew Schroeder, M.S., will co-present.  Mike and Matt have worked on site assessment and remediation projects together for more than 15 years.

 Thursday, March 22, 2012

9:00 am to 11:00 am

(please arrive between 8:30 am and 9:00 am)

Best Western (Octaviens)

559 Bloor St. W.

Oshawa, ON L1J 5Y6

There is no cost to attend, but space is limited!

To reserve your space, contact Agnes

( at 519-979-7300

Correlation Does Not Equal Causation

Twisted logic:  You used chemical A.  Chemical A is found in the groundwater; therefore, you are responsible for the contaminated groundwater.

Correlation does not equal causation. Those involved in science and statistics are familiar with this phrase.  Correlation between two variables does not automatically imply that one causes the other. Correlation might provide us a clue, but all of the variables must be examined.

Examining all the potential causal factors is work, but it is where truth is found.

What Happens To Chemicals in Soil?

Dr. James Dragun will once again teach his soil chemistry class at the 22nd Annual International Conference on Soil, Water, Energy, and Air. This is the 11th year Dr. Dragun has been asked to teach at this conference.

The conference will be held March 19-22, 2012, at the Mission Valley Marriott in San Diego, California.

For more information about the conference, click here

For more information about the Dragun Corporation go to