U.S. Water News Online
LOS ALAMITOS, Calif. -- Certain trees, it seems, are heavy
Poplar trees planted at the Joint Forces Training Base by an
engineering firm are cleaning jet fuel out of the soil. Mature
poplars drink 20 gallons of water a day.
Through a process called phytoremediation, the trees are breaking
down and soaking up residual fuel that leaked from underground tanks
when the base was a Navy air station.
Experts said the trees' roots release oxygen, sugars and alcohols
that feed the bacteria in the soil that in turn break down the
contaminants. The bacteria or microbes in the soil would eventually
remove the contaminants, but that could take thousands of years.
Organic contaminants that get past the roots and into the tree are
either contained in the tree or metabolized and released as oxygen or
carbon dioxide into the air.
The jet fuel leaked when the base was a naval air station from
1942-1972. One of the three 210,000-gallon underground fuel tanks
leaked fuel, creating a contaminant plume up to 5 feet thick.
Cleanup started seven years ago with construction of a trench to
capture contaminated water. A pump-and-treat system was installed to
take out the contaminants. These efforts removed 36,000 gallons of
fuel in nine months.
A vacuum extraction system was then installed, reducing
contaminant levels to residual or nonmeasurable concentrations.
Scientists planted 160 Italian hybrid poplar trees two years ago
to help soak up any remaining pollutants. Poplars were chosen for
their deep roots and thirst.
"They're very enthusiastic water-seekers," said Troy Hardin,
environmental scientist at the base.
The mechanical pump system will continue to operate for two to
four years, then the trees will replace the pumps. The
phytoremediation program will save the military $900,000 over 10
years, officials said.
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