2008 CPEO Brownfields List Archive

From: Lenny Siegel <lennysiegel@gmail.com>
Date: Sun, 13 Apr 2008 17:35:08 -0700 (PDT)
Reply: cpeo-brownfields
Subject: Re: [CPEO-BIF] EPA releases primer: Vapor Intrusion Considerations for Brownfields Redevelopment
A Brief Review of "Vapor Intrusion Considerations for Brownfields 

Lenny Siegel
April 2008

EPA's March 2008 Brownfields Technology Primer, "Vapor Intrusion 
Considerations for Brownfields Redevelopment," (see 
http://www.brownfieldstsc.org/newPublications.cfm?tabS=2) is indeed a 
good introduction to the technical issues surrounding the potential for 
vapor intrusion in new construction. But CPEO's recent work with vapor 
intrusion community stakeholders, as well as our reviews of new schools 
in New York City, demonstrates two important gaps in the document.

First, the primer summarizes what we consider robust guidance on HOW to 
build on property with vapor intrusion potential, but it does not ask 
which contaminated sites should be avoided, particularly when siting new 
homes, schools, or other sensitive uses. I remember hearing from a state 
regulator responsible for reviewing school-building plans. She told me 
that her agency's position is that with enough effort and resources, 
almost any site could be made safe for students. That may be 
theoretically true, but it doesn't really help the school boards and 
local governments that face this dilemma.

Perhaps the authors of the primer felt that the decision WHETHER to 
build was beyond the scope of their office, which is a Technology 
Support Center. Unfortunately, those responsible for making land use 
decisions usually lack the technical expertise to consider the challenge 
of vapor intrusion. Those with the technical expertise could construct a 
decision-tree or list of questions to help the local officials who 
usually end up making the call. As I have written before, I would start 
with objective of keeping sensitive uses off of properties likely to 
experience vapor intrusion unless there are no viable alternatives.

Second, there is a need for better guidance on long-term monitoring, 
both for structures that are being mitigated and those adjacent to 
mitigated buildings, but which are not yet being mitigated, or at least 
not yet being ACTIVELY mitigated.

All too often, mitigation measures, such as active sub-slab 
depressurization systems, are put into place, tested once, and then 
forgotten about. At the most basic level, there is a need to warn when 
such systems break down or are turned off - with contingency plans for 
restoring them to full operations.

But more is needed. Engineering data - showing that systems are creating 
pressure gradients - is not enough to show that the indoor air is safe.

The condition of vapor barriers should periodically be evaluated. In 
many parts of the country, ground movement due to freeze-thaw or seismic 
activity can create cracks and tears. And one hole drilled - for utility 
repair, for example - through a membrane may be enough to undermine its 
integrity. Mitigation systems can be run in reverse with tracer gases to 
determine whether vapor barriers remain intact.

Of course, indoor air testing is the best way to determine whether the 
systems are working. Ideally, the air should be tested twice in a 
season, once with active mitigation on and once with active mitigation 
turned off. That way both the potential for vapor intrusion, the 
viability of the remedy, and health risks can all be assessed. This 
applies to commercial buildings or schools that rely upon heating, 
ventilation, and air conditioning systems, as well as structures reliant 
upon subslab depressurization.

For buildings without mitigation: While community stakeholders advocate 
installing mitigation in structures that are literally or quantitatively 
borderline, there are many places where that isn't done - particularly 
when problems are discovered late in the development process. People 
need re-assurance that contaminant migration or other new conditions 
haven't made their buildings unsafe. Since in these cases there is no 
mitigation to confirm, indoor testing is the only viable monitoring 

In either case, I am not suggesting endless, frequent sampling, but 
based upon the nature of the structure, geological conditions, and the 
fate and transport of the contamination, there should be a reasonable 
monitoring schedule that lasts as long as the risk.

Finally, before long I expect volatile organic compound monitors, like 
smoke detectors or methane monitors, to become available within the next 
few years, to measure cost-effectively low concentrations of a small 
number of target chemicals. Integrated into long-term management or even 
routine building inspection, such devices would both reduce the costs of 
monitoring after construction and heighten the confidence of building 
occupants that their environment is indeed safe.

Sure, such alarms could be triggered by household chemicals or 
off-gassing from dry-cleaned clothes. But that's not much different that 
a shower setting off a smoke alarm. The resident or other occupant needs 
to figure out what set off the device. I believe it will lead people to 
reduce their exposure to hazardous chemicals from sources other than 
vapor intrusion, and that's a good thing.

In the long run, development policies and technologies that consider 
vapor intrusion before it happens will make building occupants safer, 
happier, and less litigious. And that will make it easier, not harder, 
for those who undertake brownfields projects.


Lenny Siegel
Executive Director, Center for Public Environmental Oversight
a project of the Pacific Studies Center
278-A Hope St., Mountain View, CA 94041
Voice: 650/961-8918 or 650/969-1545
Fax: 650/961-8918

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