City Of Leesburg and Holloway Technology - A Glimpse Of The Future

TECHNOLOGY & PRACTICE
Florida utility tests stormwater retrieval


Vegetation is thriving around this water feature that doubles as an irrigation
storage and stormwater basin. No municipal water has been added to this test bed
planting in the six months since it was installed.


The city of Leesburg, Fla., just northwest of Orlando, is full of the kind of
developments that typically have at least one large common area and an intensely
landscaped entrance. When the economy recovers and new developments start going in,
the city government — which runs the water utility for the town of 20,000 and
another 20,000 people nearby — is testing a method of irrigation for those areas
that could eliminate the need for groundwater irrigation completely.
So far, the tests are proving successful.

"I was looking for a solution to let the entrances and boulevard areas look nicely
landscaped, but not be so much of a demand on our treated groundwater resources,"
says Ray Sharp, Leesburg's director of environmental services.
So, Sharp contacted a local tree grower who has three US patents and several
international patents for a method of irrigation for the trees on his farm that uses
essentially no groundwater.

The system used is strikingly simple. Before landscaping, large sheets of
polyethylene plastic are installed, creating an artificial impermeable basin. Any
stormwater that flows onto that basin is directed into a holding pool in a catchment
area.

That holding pool is designed to be a water feature within the landscaped common
area. To keep the water quality at levels needed for plant irrigation, the test has
been using catfish in the pond to eat algae. So far there have not been problems
with excessive levels of algae or Cyanobacteria in the water.

The system was first tested in the ornamental tree nursery run by a retired
physician, Rufus Holloway. The trees in pots were simply placed on top of the
polyethylene, and periodically flooded. The trees would get water from the roots up,
which is much better for the plant, ensuring that all the roots get wet. Drip and
sprinkler irrigation invariably miss some portion of the roots.

After the trees had all they could absorb, all of the additional water runs back
down into the basin. When dry, the plastic would reflect the sun, warming the plants
so they would grow faster and helping control aphids and other pests that colonize
on the underside of leaves.

Florida has been experiencing some drought-like conditions, at least by Florida
standards, over the last few years — although Florida drought levels of 30 inches
(75 centimeters) of precipitation per year would be luxurious in other parts of the
country.

Still, the test project results are indicating that with even about 20 inches (50
centimeters) of rain per year, the closed system will be recharged enough to operate
with no inputs of groundwater.

For the city of Leesburg, that would mean completely eliminating the biggest single
user of treated groundwater in any particular housing development.
"During the hot months, as much as 80 percent of our water is going to landscaping
uses, and that's all treated water coming out of the aquifer," Sharp says.
That's why he wanted to know if what worked on that closed system on a tree farm
would work in a landscaped area. Even though Holloway invented the method, he
initially didn't think it would work to put dirt on top of the basin, thinking it
would clog the pipes that return water to the holding pool.

"I'm amazed, frankly, that it works as well as it does," Holloway says. He said the
key is to use a very sandy mix of soil. "Luckily we have plenty of sand here.
Florida is really just one big sand bar."

The other surprise for Holloway has been the low turbidity of the water. He says in
one test project with a holding pool of 6 million gallons (22,700 cubic meters) used
for irrigation for more than five years, the water remained clear and well balanced
with no chemical treatments. When he drained the pool he found less than an
inch-deep layer of muck that needed to be cleaned out.

The test project with landscaping was built and planted in June of 2009, and Sharp
says that it is already exceeding his expectations. The plants were thriving within
days, which Sharp said is unusual given the heat that time of year.
"Most of the time when people around here plant in June they have the sprinklers on
24/7 just to make sure the plants survive. We had new growth in the roots in just a
few days. It was amazing," Sharp says. He added that the pond water is clear and
does not have any unpleasant smells.

The project is going so well that he's hoping when the economy turns around and
developers start looking at building again that they will use this method for
planting in common areas, either just by persuading them or perhaps by using
regulation.

"We don't just want to be in the regulation business; we want to be in the solutions
business," Sharp says. "That's why I'm so excited that this is working well."
It's not just working well to save water, the test project is working as its own
ecosystem.

"The catfish eat the algae, and the tilapia eat some of the waste, and we have birds
that eat the fish. Everyone seems to be pretty happy," Holloway says.
He says he's also happy that the tests have gone so well and that he's had such good
partners with his hometown officials from the city's water utility. "I'm
particularly pleased," Holloway says, "with how the folks from Leesburg have been so
positively involved with this project."

The tests have been funded or aided in some part by the city of Leesburg, along with
the Florida Department of Agriculture and Consumer Affairs, the Florida Department
of Environmental Protection, and the Saint Johns River Water Management District of
Florida. Holloway also worked with the University of Florida.
Additional AWWA Resources
*       
http://apps.awwa.org/ebusmain/OnlineStore/ProductDetail/tabid/55/Default.aspx?ProductID=20648
Groundwater Resources: Sustainability, Management, and Restoration
         http://apps.awwa.org/ebusmain/OnlineStore/ProductDetail/tabid/55/Default.aspx?ProductID=6740
Water Conservation Programs—A Planning Manual, First Edition (M52)
         http://apps.awwa.org/ebusmain/OnlineStore/ProductDetail/tabid/55/Default.aspx?ProductID=6471
Handbook of Water Use And Conservation
Scott Yates, Contributing Editor
Posted: 12/22/2009