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More Stringent water Vapor Intrusion Levels | The .03 Attenuation Factor | Water Intrusion

More Stringent Water Vapor Intrusion Levels To Come? | The .03 Attenuation Factor. | Water Intrusion

Vapor Intrusion

The Reynolds Group (TRG) is tracking developments by the California regulatory community to create and enforce more stringent Vapor Intrusion (VI) “rules” at environmental clean-up sites. If these “rules” are enacted, “closing” cases in reasonable time frames and costs may become impossible. Liabilities for real property owners will increase exponentially. TRG would like you to help us monitor and give us your opinion about the possible adoption of new attenuation factors that are being considered for VI indoor air calculations here in California.

For purposes of this blog post, we will call the new rule “0.03 Attenuation Factor” (0.03 AF).  Since the early 2000s, regulators have placed additional focus on VI from Volatile Organic Compounds (VOCs) into building spaces that humans occupy. VI “standards” have evolved from literally nothing in the early 2000s to levels now, that in some cases, may require engineering controls to mitigate vapor exceedances into breathing spaces.  In our professional practice, recently we have generally been working with the San Francisco Regional Water Quality Control Board’s (SFRWQCB) guidance documents and HERO Note 3 levels (HERO Note 3) that have also become more restrictive (click here to read more).  

California regulators are currently considering the 0.03 AF that is 30 times lower than existing HERO Note 3 standards.  In our engineering practice right now, there is an uneven application of this rule by the regulating community (DTSC, Boards, etc.)  on Responsible Parties (RP’s or “contaminators”. Some regulators are immediately adopting and enforcing the 0.03 AF, others are adhering to the HERO Note 3 guidelines until “something definitive” is handed down to them.  There may still be a chance, if the regulated community objects, to create more reasonable alternatives have no change.

Applying the 0.03 AF in cases that we see will cause site assessments to expand over much larger areas and make closure levels extremely difficult — if not impossible — to achieve.  In addition, the regulators risk having to apply the o.03 AF to closed sites likely re-evaluating them. Some will argue that environmental justice groups will clamor to re-open old closed sites in the interest of public health and fairness. While regulators justify the move to stricter standards as “avoiding cancer deaths” based on human health inhalation risks, the potential costs to the real estate markets and liabilities for owners could be in the billions of dollars. Is this additional protection worth the cost?  While the 0.03 AF will provide consultants and regulators with a never-ending supply of work, the havoc caused to owners and neighboring properties of VOC-impacted real estate could be tremendous.  As the “standards” are now, assessing and closing sites to the existing HERO Note 3 Standards is a challenge. 

Regulators who we ask about the status of the 0.03 AF don’t know the facts or about whether the 0.03 AF will be applied as a “guidance”, “standard”, or “regulation”.  Few know how it will be publicly vetted. Some say it may be canceled altogether. Adopting the 0.03 AF seems to be a scary proposition.

In TRG’s three decades of practice, we have seen the “environmental pendulum” swing back and forth. For example, the clean-up standard in LUST cases for benzene in groundwater was relaxed from the Maximum Contamination Level of 5 micrograms per liter (µg/l ) to 3,000 µg/l in some instances under the Low Threat Closure Procedure (LTCP). From a soil vapor standpoint, for a reference point, using the 0.03 AF for a benzene impacted site that is non-UST related would result in having to achieve a 6 µg/m3 in subsurface soils while the same benzene on a Leaking Underground Storage Tank case could be left in place at 280,000 µg/m3 (with a bio attenuation zone).  This is about a 40,000 times order of magnitude difference.

Fro a frame of reference, 0.03 AF concentrations result in indoor air concentrations that are lower than Proposition 65 notice requirements and orders of magnitude lower than Occupational Safety and Health (OSHA) exposure levels which govern exposure to workers.  Some attorneys we have spoken to believe that using “East Coast” data sets in our “West Coast” setting is a ridiculous way to create “rules”.

We have seen that Vapor Intrusion Public Workshops coordinated by the DTSC would be held in Sacramento but they have delayed and then deleted from their schedule. (https://video.calepa.ca.gov/).  We can update you if you like when we hear more.

TRG will keep you updated on developments as we monitor the situation.  If you wish to be added to our Subscription List please click this link. Do you know of any group or lobbying effort that is being assembled to address this matter? Please let us know.  To share with us please click this link.

More Stringent Vapor Intrusion Levels To Come? The .03 Attenuation Factor.


     Current list of DTSC Public Workshops:  https://video.calepa.ca.gov/

     The DTSC’s blog collects VI guidelines and rules: http://vapor-intrusion.blogspot.com/2013/04/california-department-of-toxic.html

     SFRWQCB Hero Note 3 Guidance 2019: