2001 CPEO Brownfields List Archive

From: Lenny Siegel <lsiegel@cpeo.org>
Date: 24 May 2001 19:40:31 -0000
Reply: cpeo-brownfields
Subject: [CPEO-BIF] Emissions Questioned at Redeveloped "MEW" Superfund Site
The other night, on invitation from some neighbors, I attended a
briefing on the ongoing cleanup of the "MEW" Study Area, located about a
mile from my house in Mountain View, California. This is the Superfund
cleanup on which I "cut my teeth," starting nearly two decades ago.

The briefing was organized with the assistance of U.S. EPA Region 9. It
took place at Locus Technologies, principal consultant for the
responsible parties. The presenters were from Locus as well.

MEW stands for three streets, Middlefield, Ellis, and Whisman, which
along with Bayshore Freeway (U.S. 101) form the general boundaries of
the study area. There are actually three National Priorities List (NPL)
sites in the study area, and most if not all of the responsible parties
were in some way involved in semiconductor manufacturing in the 1970s.
Indeed, many people regard this as the birthplace of Silicon Valley, the
site at which Fairchild Camera and Instrument, as well as the companies
it spawned, such as Intel, first built transistors and integrated circuits.

Several companies, at numerous sites within the study area, had released
trichloroethylene (TCE) and other contaminants into the soil and
groundwater. These contaminant streams combined to form a massive
underground plume, about two miles in length, extending through the
upper aquifers. At some locations in the uppermost aquifer,
concentrations reached 1000 parts per million. 

The plume spread north under Bayshore Freeway, combining with similar
contaminants from Moffett Naval Air Station, itself an NPL site, and
(apparently) from NASA's operations at Ames Research Center. (Ames,
historically contiguous to Moffett Field, now owns most of the former
Naval Air Station.)

Fortunately, the plume tended to move away from Mountain View's water
supply wells, the nearest of which is about one mile to the south, and
only at two locations - the sites of abandoned agricultural wells - was
contamination detected in the deep aquifer from which Mountain View
obtains about a tenth of its water supply. (The remainder is imported.)
Years ago Mountain View commissioned a study showing that during a
drought, its pumping could pull contamination toward the supply wells,
but the MEW consultants say that now the underground gradient is
upwards, with water from the deep aquifer actually pushing up toward the surface.

In general, the MEW cleanup is considered successful. The private
responsible parties have spent over $100 million. Source controls at
each source area include slurry walls, soil vapor extraction,
excavation, and pump-and-treat. IN 1998 the MEW responsible parties
started up two regional extraction systems, one south of Bayshore and
one north of Bayshore. 

They conducted a two-year remedial action evaluation in 2000, finding:
1) the plume is contained;
2) a large mass of volatile organic compounds have been removed;
3) that average contaminant concentrations are declining significantly
both north and south of the freeway. 
The consultants recommended a few changes in pumping based upon their
results. The review showed that TCE concentrations at one of the deep
aquifer sites had fallen below the unusually strict .8 parts per billion
action level, so the extraction pumps at that spot have been turned off.

Most of the old buildings have been torn down, and new dot-com offices,
including Netscape's headquarters campus, are located on the property.
In fact, U.S. EPA features the site on the cover of its new brochure,
"Reusing Superfund Sites" (EPA/540/K-00/004, October, 2000). It says,
"By 1999, all the available office space had been leased and most of the
remaining property was at some stage of development."

But the thriving reuse of the property and improvements and
redevelopment  of adjacent neighborhoods have brought new concerns. Some
of the workers in the industrial park and residential neighbors, on
average more affluent and educated that the people who worked and lived
there before contamination was discovered, are worried about the
contamination. It doesn't take long to reassure most people that they
are not drinking contaminated groundwater, but  the risk from off-gas
emissions from the treatment system is more difficult to dismiss.

Most of the extraction systems in the MEW study area use air strippers
to remove TCE from extracted groundwater. Those constructed after 1989
capture the resulting air emissions with carbon, which is incinerated
off site (in another state, I believe), or destroy them with ultraviolet
radiation. However, there are three 45-foot air stripping towers,
located on former Fairchild property, which have no off-gas treatment.
One, in fact, sits within a Netscape courtyard. The towers are highly
visible - they remind me of the old rocket-to-the-moon ride at
Disneyland - so they raise questions. 

At the briefing, the consultants described risk assessments which found
that air emissions from the site were not likely to cause the one excess
cancer in a population of a hundred thousand that the Bay Area Air
Quality Management District uses as a risk standard. They said that the
assumptions used in the risk assessment were very conservative, and they
said that the "hazard index" was used to assess other potential adverse
health impacts. They also pointed out that emissions from the air
strippers are far below those allowed by the applicable air permits.

Still, some of my neighbors are concerned. They question why one in a
hundred thousand, rather than one in a million, was the standard. They
note that the calculated risk is marginally below the standard. And they
believe - as I have suggested - that the cost of treating the off gas is
marginal, particularly when compared to overall project cost.

The air district is unlikely to impose a better technology, even as part
of its annual permit renewal process, because the initial permit for the
three towers was issued before it promulgated its current rule in  1989.
All that community members can do, for now, is try to pick apart the
risk assessment's assumptions. When, in 2003, the MEW remedy is
scheduled to come up for five-year review, there may be a forum for
insisting upon change.

During 1980s, the early years of Superfund cleanup in Silicon Valley,
local activists - organized by the Silicon Valley Toxics Coalition -
asked for off-gas treatment. We generally were not successful until the
Air District issued new rules in late 1989, and those rules were not retroactive.

The MEW case illustrates how the "success" of such cleanup may motivate
a new generation of activists to re-raise such issues. The redevelopment
of the MEW area and the movement into the area of educated, concerned
people who knew not of local Superfund sites when the bought their
homes, has once again made treatment, at a site where cleanup is
generally regarded as successful, a public controversy.


Lenny Siegel
Director, Center for Public Environmental Oversight
c/o PSC, 222B View St., Mountain View, CA 94041
Voice: 650/961-8918 or 650/969-1545
Fax: 650/961-8918

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