Residents urged to
participate in testing to determine whether dangerous vapors have entered their
homes through basements
by Tesha M. Christensen
Southeast Como residents are being urged to have their homes
tested for a potentially harmful vapor.
“The most important thing right now is for residents and
property owners within the designated area to sign up to have the testing done
at their property,” noted Julie Kadrie of the Minnesota Department of Health.
The testing and any mitigation needed will be free for
residents.
Officials don’t yet know if chemicals vapors are getting into
people’s homes through their basements, and that’s why they are asking the 200
affected residents to cooperate and have their homes tested.
Over 160 people showed up at meetings in mid-November to
learn about the issues, and 68 access agreements were signed. According to
Kadrie, “In general, people seemed most concerned with past and current
exposures, history of site, property values, making sure that everyone knows
about it in the neighborhood, what is going to happen next, who will pay for
remediation, and how will information be distributed.”
THE
PROBLEM
The issue in the Como neighborhood of Minneapolis stems from
when General Mills conducted chemical research at property it owned at 2010
East Hennepin Ave. From 1947 until 1962, workers dumped volatile organic
compound (VOC) solvents, primarily trichloroethylene (TCE,) in a soil
absorption pit.
General Mills has been working to clean up the site since
1985. In 2010, TCE concentrations were low enough that the pump-out system was
shut down.
However, some of the groundwater in the area is still
contaminated with TCE, and could release TCE vapor that can rise through the
soil and seep through basement and foundation cracks into homes and other
buildings, where it could be inhaled by people. This is known as “vapor
intrusion.”
Testing in October within the right-of-way revealed TCE
levels soil gas samples, which prompted this recent alert.
HEALTH
CONCERNS
TCE is most dangerous for unborn children, infants, children,
and people with impaired immune systems.
Drinking water in the area has never been a health issue as
this area is served by city water and there were no wells that drew from the
contaminated plume.
Long-term exposure to TCE has been associated with liver,
kidney and blood cancers, as well as fetal heart abnormalities. Health
officials are also concerned about some of the short-term effects of inhaling
vapors from the solvent.
The birth defect registry does not indicate any current
problems. However, Kadrie cautioned that birth defects surveillance is in its
early stages of development in Minnesota, and data for the 55414 zip code only
dates from 2006-2010. “It takes many years to collect enough data to be able to
identify trends in the occurrence of birth defects,” Kadrie said. “MDH monitors
46 structural birth defects and 15 of those are congenital heart defects.
Hennepin and Ramsey counties are the counties where congenital heart defect
data has been collected the longest in Minnesota.”
Officials have not yet received data on cancer rates from the
Cancer Surveillance System, which goes back to the late 1980s.
THE
FIX
If TCE levels in the soil beneath any building or home are
above the safe level set by the MPCA and the MDH, General Mills will install
vapor ventilation systems, which work like radon mitigation systems.
Some people may be able to detect TCE at levels lower than
the reported odor threshold, while others may only detect it at higher
concentrations. Officials stress that just because you can’t smell TCE doesn’t
mean there is no exposure. Sampling and testing is the best way to know if TCE
is present.
Licensed contractors will test homes within a few block
radius of the Hennepin Ave. property. Vapor samples will be collected from
directly beneath the basement floor through a small hole drilled in the floor,
a process that takes about 45 minutes. Sub-slab samples are more accurate than
indoor air samples, which can be cross-contaminated by common household
products, such as cleaners and adhesives.
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