CPEO Comments on "MEW" Five-Year Review

[Lenny Siegel <lsiegel@cpeo.org>]

Below are my comments, on behalf of CPEO, on U.S. EPA's draft Five-Year
Review of the Superfund cleanup at the "MEW" Study Area in Mountain View.

That June 18 draft may be downloaded from
http://www.whisman.net/nmac/

Lenny

***

TO: Alana Lee, U.S. EPA
FROM: Lenny Siegel, CPEO
SUBJECT: MEW Study Area Five-Year Review
DATE: July 14, 2004

As the volunteer administrator for the Silicon Valley Toxics Coalition's
Technical Assistance Grant for the MEW (Middlefield-Ellis-Whisman) Study
Area, I support all of the general and specific comments submitted by
the Coalition. I am adding my own comments, as Executive Director of the
Center for Public Environmental Oversight, to highlight key issues that
I consider important to the Mountain View community.

First, the MEW Superfund response is in a number of ways an exemplary
cleanup. Though there are still allocation-of-responsibility issues
between the MEW responsible parties and the Navy, the MEW parties and
EPA (as well as the Navy, NASA, and state regulators) have acted
consistently, over the past two decades, to protect our drinking water
and other potential drinking water supplies. The local investigation of
vapor intrusion is a groundbreaking effort, and the responsible parties
deserve credit for taking some actions in the absence of orders to do
so. With the formation and support of the Northeast Mountain View
Advisory Council in 2003, EPA and the MEW parties have joined the Navy
in making Mountain View a national model in the public oversight of the
cleanup of contaminated properties.

However, the vapor intrusion investigation still falls short because it
fails to acknowledge the outdoor air pathway. There have been many
outdoor sampling results suggesting that trichloroethylene (TCE)
contamination, in the outdoor air in and around the MEW Study Area,
frequently exceeds an exposure level corresponding to one in 100,000
excess lifetime cancers. EPA says that such readings are acceptable,
because they are within the risk range between one in 10,000 and one in
a million excess lifetime cancers. I, and many people in the Mountain
View community, believe that one in a million should be the default
action threshold. That is, EPA and the MEW parties should consider
additional remediation or mitigation above the one-in-a-million level,
particularly because a much larger population may be exposed to
"ambient" TCE in that range.

It may turn out to be impractical to address fully the outdoor air
contamination, but the current investigation should be based upon a
conceptual site model that considers all sources, all receptors, and all
pathways. If outdoor air exceeds the one-in-a-million threshold only on
rare occasions, this may be acceptable. But if exceedances are common,
then venting subsurface and indoor contamination to the outdoor air may
not be a sufficient response. Additional or accelerated remediation may
be necessary. It appears that a large mass of volatile organic
compounds, including TCE, is continuously making its way to the surface.
That problem should be addressed in its entirety.

Furthermore, the recent discovery of indoor air contamination,
presumably from the MEW plume, in the residential area west of Whisman,
is troubling. Either EPA and the MEW parties failed to recognize the
risk posed by TCE in this area, or (less likely) the plume is expanding.
Members of the community have little confidence in the reported plume
boundary. Though we are pleased that action is finally being taken in
this neighborhood, we are concerned that residents may have suffered
exposures for three decades or more. It's imperative that EPA and the
responsible parties act quickly to define better the groundwater plume
and any vapor intrusion occurring in this area.

Finally, I am particularly concerned that EPA headquarters has deferred
finalization of its Draft Toxicity Assessment for TCE, in apparent
response to pressure from the Defense Department, other polluters, and
the White House. This Assessment was praised by EPA's Science Advisory
Board peer review committee, because it considered the impact of the
chemical on susceptible populations, such as young children. While the
final cleanup goals for TCE are under review, EPA and the responsible
parties should continue reasonable investigation, mitigation, and
remediation based on the provisional screening levels.

TCE is not a naturally occurring compound. To the degree that its
presence in our environment is a result of activities by the responsible
parties and their corporate predecessors, they should restore our water,
soil, and air to protect all the potentially affected residents and
workers in the Mountain View area.


--


Lenny Siegel
Director, Center for Public Environmental Oversight
c/o PSC, 278-A Hope St., Mountain View, CA 94041
Voice: 650/961-8918 or 650/969-1545
Fax: 650/961-8918
<lsiegel@cpeo.org>
http://www.cpeo.org