These 10,000-gallon holding tanks are the home for salvaged rainwater from the roof of the Leon County Sustainable Demonstration Center. Leon County, Fla.The Leon County, Fla., Sustainable Demonstration Center converted its rooftop into a rainwater collection system to reduce the need for potable water and the amount of storm water discharge into sewer system.
A water audit showed that the Center had been using about 570,000 gallons of water a year from the municipal water system for its extensive botanical garden and demonstration food crop garden.
Gutters and downspouts channel rooftop runoff into four salvaged 10,000-gallon holding tanks buried on the site, rather than discharging water onto the landscape or imperviousparking lots. A submersible well pump with an air-tight sealed motor pushes water from the tanks to the irrigation system. The single-wall fiberglass underground tanks, which were previously used for petroleum storage, were cleaned and retrofitted for their new purpose. Electronic valves enable the Center to use potable municipal water in dry periods if the storage tanks cannot meet the need for mist and drip irrigation.
One unique feature of the system is the use of HDPE “smart boxes” that filter debris from the rainwater and regulate outflow to the storage tanks, maintaining consistent water levels in the tanks and directing hydraulic overflows to roadside stormwater installations. Those smart boxes, developed by Leon County’s staff, helped the rainwater recovery system earn a patent. Other innovative elements of the rainwater recovery system include microcontouring of the existing roof.
Tom Brantley is chief of building engineering, Leon County, Fla. He helped design the rainwater runoff system. Will Sheftall works in Leon County as a University of Florida extension agent for natural resource management.
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