No environmental professional ever wants to be in the uncomfortable position of having a past Phase I ESA report put under the glaring eye of scrutiny in a professional liability lawsuit. Drawing from years of expertise as an expert witness in these cases, Anthony Buonicore, P.E., BCEE, QEP and CEO of The Buonicore Group, delivered a highly-rated presentation at our Due Diligence at Dawn/Dusk series this year in which he guided hundreds of DDD attendees through five real-world case studies. Each case revolved around a particular element of the ASTM E 1527 standard, including a range of technical topics (e.g., non-scope issues, historical research, professional judgment, etc.). The discussion of each case study addressed these questions: Was the “standard of care” provided by the EP deficient? How did the EP’s performance compare with “customary practice”? Did the scope of work meet the requirements in ASTM E 1527? Our first case study, published last month, dealt with non-scope issues. The second case study in this EDR Insight Summer School series is below, and deals with vapor migration risk.




CASE STUDY: Vapor Migration


  • A property developer wanted to acquire a parcel of vacant land and build a development of single family homes.
  • A consultant was retained in 2006 to conduct a Phase I according to the ASTM E 1527-05 standard.
  • A former industrial site that used chlorinated solvents was identified adjacent and hydraulically cross-gradient from the target property made aircraft parts.
  • Review of the contaminated plume delineation study on this former industrial property indicated that the contaminated groundwater plume was not on the target property.
  • The consultant did not identify any recognized environmental conditions on the target property and the property was acquired.


  • After the first phase of residential development was completed and new houses sold, one of the homeowners complained of “unusual odors.”
  • An indoor air investigation was conducted and identified the presence of TCE and PERC in the homes.
  • An environmental consultant retained to investigate identified the source of the indoor air contaminants as vapors volatilizing from the contaminated groundwater plume at the adjacent former industrial site.
  • Subsequent indoor air investigations revealed a number of homes with levels of TCE and/or PERC.
  • The developer incurred the cost of installing vapor intrusion mitigation systems in all impacted homes.
  • Homeowners sued the developer for impact on health and property value diminution.
  • The developer sued the Phase I consultant for negligence in not identifying vapors migrating onto the property from the adjacent former industrial site as a REC, and sought damages.


  • The ASTM Phase I ESA is driven by CERCLA, and CERCLA does not differentiate by the form of the release (solid, liquid or vapor) to the environment; only that the release be a hazardous substance.
  • TCE and PERC are hazardous substances.
  • The CERCLA definition of “environment” includes the subsurface.
  • The CERCLA definition of “release” includes hazardous substances “emitting” and “escaping” into the subsurface environment.
  • Vapor migration is included as a consideration in a Phase I ESA.
  • The ASTM REC definition includes “releases into structures on the property.”
  • The state where the property was located has a draft vapor intrusion guidance document and the consultant should have been aware of this.
  • The consultant was negligent in the conduct of the Phase I ESA by not identifying the potential presence of hazardous vapors on the property.
  • Had the consultant identified the potential presence of hazardous vapors migrating onto the property, the developer would not have acquired the property without further investigation.
  • The consultant’s negligence caused harm to the property owner and damages were sought.


  • The ASTM E1527-05 standard does not include a vapor migration investigation in the Scope of Work.
  • The standard of care and customary practice for conducting a Phase I ESA does not include consideration of vapor migration.
  • There is no consensus methodology for evaluating vapor migration in a Phase I [non-intrusive type].
  • EPA does not include consideration of the vapor pathway in its Hazard Ranking System (HRS) for identifying Superfund sites.


  • The case was settled by the insurance company that provides the consultant’s E&O insurance.

“We didn’t have much of a defense because we didn’t know much about vapor at the time. And the plaintiff’s attorney was very up to speed on CERCLA. And the key here was that CERCLA doesn’t differentiate by the form of the release.” ~ Buonicore


  • If you conducted Phase I ESAs prior to November 2013 (when the ASTM E1527-13 standard was published) and did not consider vapor migration in those Phase Is, there is liability risk. It would be prudent to work with your legal counsel to develop a strategy to respond to a potential future lawsuit claiming that you were negligent.
  • Consider the following in developing a response strategy:
    • Industry consensus on a vapor migration screening methodology for Phase I ESAs was not developed and published until 2008 (ASTM E 2600-08 standard).
    • The ASTM E 2600-08 standard included vapor migration as a “non-scope consideration” that would be included only at the client’s request (under legal pressure that this exclusion was inconsistent with CERCLA, E2600 was revised in 2010 to delete vapor as non-scope).
    • The ASTM E 1527-13 Phase I standard published in November 2013–for the first time–specifically refers to vapor migration.
    • EPA first published a draft vapor intrusion guidance document in 2002, but only published its final version for public comment in April 2013. The final version was just released.
    • In 2008, only 14 states had vapor intrusion guidance (this increased to 23 states in 2010 and 35 states today).
    • For Phase Is conducted prior to 2002 (when EPA published its draft VI guidance), a reasonably strong case can be made for not having included vapor migration in your Phase I.
    • For Phase Is conducted between 2002 and 2005 (promulgation of the AAI Rule), a reasonable case might still be made, but this will likely be dependent in large part on whether the state where the property is located had published vapor intrusion guidance.
    • For Phase Is conducted post-2005 after EPA published its AAI Rule, it will be difficult to make a case for not assessing vapor migration since EPA in its December 30, 2013 AAI Amendment to the Rule clearly stated that the 2005 Rule included consideration of vapor migration. “EPA didn’t just say it, they had a long preamble and talked about vapor saying AAI always included it.”
    • For Phase Is conducted after 2010 (ASTM E2600-10 publication date), to make any kind of respectable case would be unlikely.


“Wherever you are, you should be keeping tabs on what your state agencies are doing on vapor. The courts will look to you as the expert.


“Talk to your attorneys about it. Otherwise, you’d better pray to St. Anthony or St. Jude to keep you from getting sued.” ~Buonicore


NOTE TO READERS: Case study 3 will address a specific case involving professional judgment. Anthony’s slides from the fall/spring DDD season are posted in their entirety here.