Some of the Keys’ biggest water customers are leading the way in reducing the demand for the precious liquid that comes to us from the mainland via the Florida Keys Aqueduct Authority’s big conduit.
One leading-edge example is Marathon’s Sombrero Country Club, which built its own desalination plant to convert saltwater to nearly fresh water a few years ago.
Bob Daniel, Sombrero Country Club’s course superintendent, said the plant, located on the west end of the club’s property, is doing just fine.
“In addition to new sod and tropical vegetation, the club installed a new reverse osmosis plant, which increases our total capacity to over 250,000 gallons,” he said. “We take groundwater — which is essentially pure seawater — with salt content around 34,000 parts per million, and reduce it down to about 200 ppm. We run our sprinklers each night from 7 p.m. to 5 a.m., irrigating each zone for 10 minutes at a time. That’s about 150,000 gallons a day.”
Sombrero’s reverse osmosis separation technology removes salt through the use of a semi-permeable membrane. The flow through the membrane transforms a high salinity, or concentrated, solution to a high purity, or “permeate” stream on the opposite side of the membrane. Pressure is the driving force for the process. While the plant’s water output is not fit for drinking, it is just fine for the golf course. “A small amount of salt is left behind on the ground,” Daniel said, “but regular rains wash it away.”
At the Keys’ other 18-hole golf course, a different technology is used. Key West Golf Course is a customer of KW Resort Utilities, which completed a wastewater vacuum collection system installation for Stock Island in 2003. The system uses treated graywater to keep thirsty plants alive and irrigate landscapes. Graywater is recycled shower, bath, dishwasher, sink and laundry water, which is 50 percent to 80 percent of residential wastewater.
Water-stressed states like Florida, California and Arizona are the leaders in recycling graywater. Florida reuses 40 percent of its treated wastewater, with California not far behind. Current water restrictions do not apply to the use of 100 percent reclaimed water.
The golf course is only one of some 2,000 customers hooked up to the Stock Island utility, which handles 350,000 gallons a day, 110 million gallons a year, conserving a like amount of FKAA potable water.
General Manager Doug Carter says the utility’s wastewater collection system has a connection line available for each Stock Island home and business owner at the property line. At $2,700 for hookup and $39.20 per month, the wastewater system is the least expensive in Monroe County. To save taxpayers another $36,000 per year, 6.4 million gallons of reclaimed water are transferred to the Monroe County Detention Center for nonpotable use.
Another customer of Key West Utilities is the Tropical Forest and Botanical Garden, which uses additional water-saving techniques to reduce the demand.
Executive Administrator Misha McRae said the garden uses timers to irrigate sections of the property after 5:30 p.m. and before 8 a.m., when evaporation is reduced. “When the sun is down, the water goes where it is supposed to go,” he said.
Stock Island is not alone. The South Florida Water Management District has approved $3,000,000 in funding for four major projects in partnership with the FKAA. The projects include two reverse osmosis desalination plants in Florida City and North Key Largo, as well as two reclaimed water treatment systems on Duck Key and Big Coppitt Key. The reclaimed water projects are already under way and designed to take advantage of highly treated effluent from new advanced wastewater treatment facilities.
Key Colony Beach is also using recycled graywater.
“When the Florida Legislature ruled in 1997 that all of the Florida Keys must be AWT wastewater treatment compliant by July 2010, we borrowed $3 million from the Florida State Revolving Fund and renovated our old 1970 wastewater treatment plant to meet the 2010 mandate, said Mayor Clyde Burnett. “If we had waited to now, the cost would be probably $7 to $8 million.”
Sixty-thousand gallons of recycled water each day are used to water the Key Colony Beach golf course, two city parks and the grounds around city hall. In the future, the city may increase the size of the system in order to provide water to some condos and homeowners.
D’Asign Source specializes in using Keys native and other salt- and wind-tolerant plants and shrubs to create landscapes that save water. While new landscapes often require some daily irrigation to get them established, later on they can survive the Keys dry seasons. Water restrictions usually include an initial grace period, during which daily watering can be done.
Dean Stoddard, a vice president at D’Asign Source, has worked there as a landscape architect for 14 years. “We accommodate the different irrigation requirements of sod and shrub zones in our designs,” he said. “We believe in Florida-friendly landscaping, lush-looking yards requiring a minimum of watering.”
He said that rain shutoff devices, which sense rainfall and shut off irrigation pumps or valves, are an example of a low-cost addition that saves water and money. An irrigation system without one is a “pure waste of water,” he said. He also strongly believes in the use of mulch to reduce water evaporation.
Kim Gabel, environmental horticulture agent for the Monroe County Extension Service, is also a proponent of using mulch.
“Treegator bags are growing in popularity,” she said. “These water-holding bladders, placed around trees and shrubs, slowly drip water to the roots, helping them get established. The mulch holds the moisture. Most people tend to overwater.”
The bags are filled with water and then the water-release holes are opened allowing the water to slowly seep out. Refilling of the bags may not be necessary for several days.