St. Tammany Parish partners with Southeastern, Comite resources to test experimental floating marshland
Wednesday, September 28, 2016 
by: Tonya Lowentritt or Rene Abadie
FLOATING MARSHLAND – Southeastern Louisiana University biological sciences graduate student Zachary Leggett ties plants to a floating platform he constructed that will serve as a floating marshland to help clean stormwater contamination in the Del Sol subdivision in St. Tammany Parish.
A relatively low-tech method of imitating a natural marshland was implemented to help
clean freshwater ponds contaminated by stormwater runoff. This research is being funded
by St. Tammany Parish Government in cooperation with scientists at Southeastern Louisiana
University and the wetlands assimilation company Comite Resources, Inc.
The effort is intended to improve water quality throughout St. Tammany through
several water quality initiatives. Included is a project in the Del Sol subdivision
of Covington that utilizes an innovative, yet relatively low-tech method of imitating
a natural marshland that will help to clean freshwater ponds contaminated by stormwater
runoff.
The $222,000 pilot project is a component of the newly initiated St. Tammany Parish
stormwater management plan, a project that was launched to help the parish determine
the most efficient and effective methods to retrofit other stormwater retention ponds,
turning them into water quality enhancers, according to parish officials.
“Improving water quality and our environment in the parish are crucial,” said
St. Tammany Parish President Pat Brister. “As we continue to research and implement
the latest, most effective strategies to address pollution and stormwater runoff problems,
we will continue to make great strides in improving the overall quality of our water
throughout the entire community. Success will also make this pilot project replicable
throughout St. Tammany and mimicked throughout the country.”
The project is being funded by the parish and implemented by Southeastern Louisiana
University wetlands expert and Professor of Biological Sciences Gary Shaffer and graduate
student Zach Leggett, who are working with Racheal Hunter of Comite Resources, Inc.
based in Zachary, La.
Rainwater runoff enters the Del Sol pond from three directions, carrying with
it sediment, oils, tar, fertilizers and herbicides that accumulate in the subdivision’s
watershed and contaminate the pond.
Leggett and Shaffer are evaluating the cleaning effects of a man-made floating
marsh in the eight-acre pond. Leggett’s hands-on project is the focus of his master’s
thesis at Southeastern.
“The floating plants take out the excess nutrients and turbidity, or cloudiness,
in the water, including fertilizers, pesticides, herbicides and other materials that
can be harmful to water quality,” Leggett said.
In the fall, Leggett and his team constructed a star-shaped, eight-armed frame
of PVC piping with four-foot wide vinyl coated crab wire between the piping that acts
as a platform and serves as a supporting structure for marsh plants, such as maidencane,
arrowhead and spider lily. The plants attached to the netting, serve as a natural
filtering mechanisms for the pond water. The predominant water plant used in the structure
is maidencane, an inexpensive plant that is easily propagated in the university’s
greenhouses before being transplanted into the frame.
“The maidencane roots are full of gas, so the plants tend to float on top; this
makes it ideal for this kind of structure,” explained Shaffer. “Maidencane is a good
plant for this purpose; the roots grow about 20 inches deep and suck up the excess
nutrients in the water and help clean the pond. As an added benefit, the structure
also becomes a huge refuge for small fish and other species.”
While water quality tests are only in the early stages, Shaffer said the pond
has become much clearer with a huge reduction in turbidity, or cloudiness. In addition,
he said, the frames are full of minnows and juvenile fish, which greatly improves
the ecosystem function of the pond.
“We expect the turbidity and nutrient levels at the site will be significantly
reduced, which means we would be successful in our efforts to remove the contaminants
and clear the water,” said Leggett. “And it would tell us whether maidencane is the
ideal plant for this process.”
Hundreds of ponds in St. Tammany Parish are in need of water quality improvement,
according to Parish officials. The Parish’s floating marshlands project, if successful,
will play a significant and relatively inexpensive role in improving water quality.
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The research project and its final report are expected to be completed in 2017
after the plants have completely covered the platform.
Members of the Water Environment Federation, a not-for-profit technical and educational
organization representing water quality professionals around the world, toured the
natural marshland site in the Del Sol neighborhood on Tuesday (Sept. 27). The professionals
were in New Orleans for the Water Environment Federation Technical Exhibition and
Conference during the week of September 24-28, 2016, and visited the site to learn
about best management practices that are being applied to existing stormwater ponds.
Registrants who participated in the tour were from throughout the United States, as
well as Singapore and Mexico.
