Arizona researchers may have discovered a dirty, hungry little secret
that could save the state countless dollars in cleanup costs at a Tucson
Superfund site.
Researchers from the University of Arizona and Northern Arizona
University are sampling wells at a state Superfund site just west of
Park Avenue, where it turns into Euclid Avenue. They're not checking for
chlorinated solvents, including the infamous, cancer-causing TCE. State
regulators found those years ago.
Instead, the researchers are looking to see whether, amid the toxic
solvents and diesel fuel, resident helpful bacteria are already chewing
up the mess. If so, they could save the state millions of dollars - and
head off a plume of contamination seeping toward the UA's drinking water
wells.
"We see plenty of evidence that micro-organisms that can degrade TCE are
present at that site," said Maribeth Watwood, a biology professor and
researcher at NAU. Watwood is collaborating with UA researcher Mark
Brusseau to assess the viability of bacterial bioremediation.
The Park-Euclid site, south of the university, includes facilities where
three companies have conducted laundry and dry-cleaning operations since
the late 1930s, according to the Arizona Department of Environmental
Quality. The site also contains diesel products, presumably from past
railroad operations.
The state agency first detected the pollution in 1990, from a well
sample on the property of Mission Uniform & Linen Service. After that,
the company initiated its own testing. For a time, the federal
Environmental Protection Agency was in charge of the site - handing the
reins to the state in 1999 - but so far Mission Linen has conducted the
only cleanup operations.
Since 2000, Mission has been extracting toxic vapors from the soil and
is designing a system to treat the water directly underneath its
property.
Workers in Mission Linen's Tucson office declined to comment for this
article. The company's attorney, Joe Drazek of the Phoenix-based firm
Quarles & Brady Streich Lang, said Mission bought the property in March
1983 and continued to operate leaking, industrial-size machines until
June 1985.
"We're not saying we have no liability," Drazek said, but the machines
were operating - and leaking - for more than a decade before Mission
took over. Still, Drazek estimates the company has spent more than $2
million on studies, soil vapor extraction and designs for the next
cleanup phase, which will require a state environmental permit to
proceed.
State officials say they're within two years of completing their own
assessments of the pollution and possible cleanup methods. The
university researchers' work is part of those assessments.
The Park-Euclid site isn't unique. With the rise of industries such as
dry cleaning and airplane degreasing came billions of gallons of
chlorinated solvents, generally known by abbreviated names like TCE and
PCE. They were dumped in the ground at many industrial sites, including
the Park-Euclid location and a large area of land around Tucson
International Airport. Chlorinated solvents have been detected in
drinking water supplies across the country. And as awareness has dawned
that the chemicals are toxic and even cancer-causing, many local, state
and federal agencies have turned their attention toward cleanup.
But traditional pump-and-treat methods are time-consuming and costly.
Cortland Coleman, an ADEQ spokesman, said the price of pump-and-treat
efforts typically reaches into the millions of dollars, though no
estimate is available yet for the Park-Euclid site.
The state has spent more than $25 million since 1988 to clean up toxins
- mostly industrial solvents, toxic metals and diesel fuel - at seven
Superfund sites around Tucson. That doesn't include resources
contributed by the federal government, the city, the county and the
industries responsible for the pollution. The U.S. Department of Defense
is engineering its own remediation of fuel and toxic metals at
Davis-Monthan Air Force base.
Pollution-chewing bacteria have been found all over the world and are
especially prevalent where there are natural gas deposits or frequent
gas spills. They've evolved to feed off the natural gas by using enzymes
to chew through specific chemical bonds. The chlorinated solvents
contain the same bonds, so the bacteria chew through them, too.
The bacteria are wasting their time on chlorinated solvents because they
get no food - but in the process, they render them harmless to people.
Watwood has participated in previous successful efforts to bioremediate
chlorinated solvents at the Department of Energy's Idaho National Lab in
the eastern part of that state. "The bioremediation campaign up there
has saved millions of dollars," she said.
Sometimes, said the UA's Brusseau, there's so much contamination that
the bacteria are overwhelmed - and that's where chemical solutions can
help.
In another project at the Tucson International Airport Superfund site,
Brusseau and his students are injecting chemicals into the ground that
can break up the contaminants quickly, and can work alone or in concert
with the bacteria by helping them finish the job.
Brusseau also has a student working full time at the Park-Euclid site,
but the work is focused on the shallower of two aquifers that have been
contaminated. It's the deeper aquifer that hosts the plume creeping
toward the UA's south campus wells.
"We know the plume is still there," he said, "And I'm not sure anyone
knows how fast it's moving." The state has installed four test wells
over the years just south of the campus boundary - the northernmost one
is near the university recreation center - and those wells have shown
chlorinated solvent contamination for years.
Monthly samples of active drinking water wells on campus are so far
contamination-free.
For more Arizona news, visit
www.azstarnet.com or
www.azfamily.com.
©The Arizona Daily Star, 2005
Securitas