[CPEO-MEF] Twin Cities plant vapor intrusion

[Lenny Siegel <lsiegel@cpeo.org>]

[Please excuse the duplicate posting. - LS]

The Twin Cities Army Ammunition Plant, in Minnesota, is a non-BRAC 
closure and a Superfund (National Priorities List) site with extensive 
TCE pollution in groundwater. The Army plans to dispose of the property 
through the General Services Administration. The city of Arden Hills 
hopes to purchase 455 acres of the property for private development, 
primarily housing.

U.S. EPA and the Minnesota Pollution Control Agency believe that there 
is a potential for vapor intrusion if the property is redeveloped, but 
the Army refuses to address that pathway. From my distant vantage point, 
I believe the Army is doubly wrong. However, I would appreciate 
additional information, confirming or challenging my observations, from 
people who are closer to the situation.

1. The Army has said that it will not transfer the property to Arden 
Hills if it is required to clean the property to a standard that will 
support the city's proposed residential use. This flies in the face of 
federal policy, which for more than a decade has said that Superfund 
cleanups should support reasonably anticipated future land use. It also 
ignores promises, made at BRAC (base realignment and closure) sites, 
that the military would conduct remediation to support communities' 
reuse plans.

It is the obligation of polluters to remediate their property. 
Sometimes, they are permitted to conduct partial cleanups if, under 
expected land use, there is no exposure above established standards. In 
this case, however, the Army is attempting to restrict the land use, 
unless it can be assured that the city or private developer will assume 
responsibility for investigating and remedial potential vapor intrusion.

Under this scenario, the purchasers will not know anything about the 
vapor intrusion risks when they agree to take over responsibility. If 
the problem turns out to be bigger than they estimate, either the 
developer and city will take a financial loss or the new residents will 
be exposed to both health and financial risks. In theory, the developer 
or city can take out environmental insurance, but why would a reputable 
insurance company write a cost-effective policy in the absence of 
credible information?

2. The Army apparently contends that it doesn't need to conduct a vapor 
intrusion investigation because it anticipates continuing 
non-residential use. Though EPA's 2002 Vapor Intrusion Guidance may be 
interpreted this way, subsequent clarifications and investigations by 
EPA regions suggest otherwise. If vapor exposures result from historic 
contamination, not the continuing use of the hazardous substance in 
question, then the Occupational Safety and Health Administration - and 
its state counterparts - do not have jurisdiction.

Vapor intrusion investigations and responses are now taking place in 
non-residential settings, including within my own community of Mountain 
View. There are two major differences for residential responses. First, 
exposure standards are higher (less protective), but only by a factor of 
about three, to account for the fact that workers go home. Second, 
commercial structures can more easily use certain mitigation systems, 
such as positive air pressure from heating and cooling systems, to 
minimize vapor intrusion.


I believe all parties would benefit if the Army were to conduct a 
thorough vapor intrusion investigation prior to TCAAP property transfer. 
It might show that the risk from vapor intrusion is acceptably low, but 
it might also show that it is low in some areas and high in others. That 
information should shape plans for carving up the property, and 
particularly the placement of housing and other sensitive uses. It would 
also make it possible to update remediation strategies - possibly 
applying innovative technologies that speed up contaminant removal or 
destruction - before new construction takes place. And it would also 
help determine what mitigation should be built into new buildings.

Conceivably, the presence of residual contamination would also require 
the imposition of institutional controls, including long-term monitoring 
and contingency plans. While these could be added later in the process, 
most developers prefer to know such requirements in advance - so they 
can weigh the value of upfront investments in cleanup or mitigation.

It may be that the Army can negotiate a deal with Arden Hills or the 
property developers, in which the transferees take responsibility for 
cleanup or mitigation in exchange for a discounts on the sale price. 
That might be OK, but only if the extent of the problem is first identified.

Lenny Siegel

--
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
http://www.cpeo.org

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