Florida Looks to Recycling, Desalination As it Faces Increasing Water Supply Crunch

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By Alan Kovski

Jan. 22 — Florida is bumping up against its limits on groundwater supply, the primary water resource for the state, officials from water management districts and water utilities have said.

Concerns about supply and environmental regulations have been pushing water utilities toward more recycling and greater use of desalination for brackish water, and water management districts have told several utilities they are maxed out on the rates of withdrawal from some aquifers.

Water stress is more commonly associated with the dry Southwest, not a state rich in wetlands where the summer rainy season routinely brings afternoon showers. But overall demand, augmented by an ever-growing population, has gradually increased the stress on aquifers even as per capita consumption has declined.

“I think really the future in Florida is indirect potable reuse,” said Dean Powell of the South Florida Water Management District, one of the state's five organizations for managing water resources. Powell is the bureau chief for water supply in his district, which serves the populous southern portion of the state, including Miami, Fort Lauderdale and Palm Beach.

Indirect potable reuse refers to the recycling of water by recharging drinking water sources, such as aquifers or rivers, with wastewater that has been highly treated, either through advanced technologies or natural processes. Many utilities in Florida have significantly increased their reuse of water with some counties recycling 100 percent of their wastewater.

Florida also is turning more to saline groundwater, which has a lower salt content than seawater and consequently is easier and more economical to filter, by reverse osmosis, for drinking water, Powell said.

Other water utility officials similarly cite indirect potable reuse and saline groundwater as growing sources of water in Florida.

‘There's Too Much Pumping.'

Florida continues to be a growth state. Its population was about 16 million in 2000 and is above 19 million now, and the Florida Office of Economic & Demographic Research has forecast a population exceeding 21 million in 2020.

“There's too much groundwater pumping, we know that, coming from the upper levels of the Floridan aquifer,” said Jason Mickel, manager of the water supply section in the Water Resources Bureau of the Southwest Florida Water Management District. The Floridan, underlying the whole state, is one of the most important aquifers.

Water withdrawals have contributed to saltwater intrusion in aquifers near the state's populous coasts, such as the Biscayne aquifer beneath Miami-Dade County.

Pumping also can threaten interconnected surface waters.

Harm Said Possible to Lakes, Rivers 

“We know if we pump too much, we will harm lakes and rivers,” Mickel said. “There has been evidence of some harm to water bodies.”

Concerns about environmental harm have limited water withdrawals that can adversely affect the Everglades and other areas, notably the Kissimmee River Basin covering a large area in central Florida.

Fortunately, the demand for more water hasn't been as great as expected, said Douglas Yoder, deputy director of the Miami-Dade Water and Sewer Department.

“The crunch that we thought was going to be progressively developing hasn't materialized,” Yoder said.

Yoder cited several factors ameliorating the demand:

• water conservation, helped by such strategies as rebates for efficient plumbing and retrofits for irrigation equipment;

• irrigation restrictions;

• growth occurring in multifamily housing rather than single-family houses;

• the recession that started in 2008 and

• a slower-than-anticipated growth rate in population.


Reduced Use Rates Holding 

“Reduction in water use in the economic downturn was about 20 percent, and it seems to be holding,” Powell said. He added that it was uncertain whether that reduction would hold as the economy improves.

Statistics on water use support the picture of reduced consumption on a per capita basis. In the Tampa Bay area, water use in 2012 was 97 gallons a day per person, down from a range of 140 gallons to 145 gallons in 1990, Mickel said.

There is still a lot of room for improvement, Mickel added.

The Southwest Florida Water Management District has funded about 300 utility projects since 1997 to increase the use of reclaimed water that has not been treated to the same extent as that intended for indirect potable reuse. For example, reclaimed water can be used to water lawns and golf courses. It is expensive to retrofit a neighborhood for such recycling, but the strategy works well when planned into new neighborhoods, Mickel said.

Some reclaimed water also goes to cooling water for power plants.

District Discharging Reclaimed Water to Aquifers 

Mickel said his district now has several projects funded to try discharging reclaimed water to areas where it percolates through the ground to aquifers. In addition, near the Hillsborough River there are “spray fields” where water is allowed to percolate through soil to the subsurface layers that can feed the river.

He estimated that about 40 percent of existing wastewater discharge in his district still could be captured for beneficial uses.

A reservoir for reclaimed water is being built in Pasco County, just north of Tampa, to hold 500 million gallons. It will store the treated wastewater in the summer rainy season for use in the dry season. Construction of the reservoir should be completed and the project brought online this year, Mickel said.

Not only the reservoir but the other forms of indirect reuse help to reduce the problem of Florida's seasonal water swings—too much rain in the summer, when flood control becomes an issue, and too little rain in the winter.

Ocean Discharge Limits Set 

One factor that will force more recycling is a state law limiting ocean discharges to protect the marine environment, notably fragile coral reefs. The law mandates that utilities using marine outfall pipes reuse 60 percent of that effluent in 20 years to the extent that it is technically and economically possible.

The Miami-Dade Water and Sewer Department tentatively plans to send some of the diverted outflow water to the Florida Power and Light Turkey Point power plant south of Miami for use as cooling water with most of the rest going to replenish the Floridan aquifer. A $150 million reverse osmosis plant would treat the water for injection into the aquifer.

The Floridan aquifer is brackish in South Florida, which means that less treatment is required—and at less cost—for Miami-Dade's wastewater before it is injected into the aquifer. Any water withdrawn from the aquifer for drinking supplies must be put through additional filtration anyway.

Miami-Dade to Address Reuse Issues 

Miami-Dade will have to send a report to the state Legislature by Feb. 15 on any issues connected with the reuse.

Desalination increasingly is seen as an option around the nation, with Florida leading the list of states with desalination plants.

Yoder said the estimated cost for Miami-Dade to address the limit on ocean discharges now is $3.6 billion to $4 billion. Extensive pipelines, treatment and pumping don't come cheap for a metropolitan area as big as Miami.

Desalination increasingly is seen as an option around the nation, with Florida leading the list of states with desalination plants.

Tampa Bay Water, a wholesale supplier of water to utilities in the Tampa Bay area, has been desalinating seawater since December 2007 to produce up to 25 million gallons a day of drinking water, though it averages much less than that. It is described as the largest desalination plant in North America.

Tampa Pulls Seawater From Cooling Outflow 

The Tampa Bay desalination plant pulls seawater from the cooling water outflow of the neighboring Tampa Electric Co. Big Bend power plant, which draws the water from Tampa Bay. One of several advantages to this arrangement is that Tampa Bay water is less saline than average seawater.

Desalination typically operates by reverse osmosis to filter the water, a technology that can also be used to treat wastewater. But the membranes for reverse osmosis can foul and clog, and the process is energy intensive and expensive.

To reduce costs, utilities look for water with lower saline content such as brackish groundwater. In some parts of the state, that can mean drawing water from a deeper aquifer or a deeper level of the same aquifer, such as the Floridan. Treatment plants using reverse osmosis are the big expense for such a strategy but nevertheless are being built in various places.

In turning to saline groundwater rather than seawater, Powell said, “it's much, much less difficult to treat it and serve it up.”

To contact the reporter on this story: Alan Kovski in Washington at akovski@bna.com

To contact the editor responsible for this story: Larry Pearl at lpearl@bna.com


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