[CPEO-MEF] indoor air sampling

[CPEO Moderator <cpeo@cpeo.org>]

The following was posted by Anne Callison <Awbarbour@aol.com>
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Lenny,

Thanks so much for your comment on the new EPA model.  A couple of
questions - post to the listserve if beneficial.  The Colorado
Department of Public Health and Environment is going
along with the Air Force and our privatized contractor saying that the
levels of TCE are testing so low that further indoor air testing will
not be required. There are approximately 200 homes known to be over the
plume coming off Lowry AFB - 13 homes were tested.

Does anyone know how soil gas vapor concentrations relate to TCE levels
at bedrock or simply the source below for the vapors?  For instance, if
the measurement at the wellhead is 120 ppb are the soil gas vapors
greater or less than they would be if the measurement at the wellhead is
25 ppb?
What effect does time have on the soil gas vapor as it rises even if its
source is being diluted down below?

Call me unscientific, but these 200 homes have been over a plume which
began some 60 years ago, and this level of testing seems ridiculously
low. And we know from previous studies that monitored natural
attenuation (MNA) is not occurring.  I believe the plume's levels are
dropping through dilution and simple spread of the plume over a wider
area.

Your comments and those of others would be greatly appreciated.

Anne Callison
Lowry AFB RAB

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