With a 15-billion gallon reservoir under construction, some neighbors worry and wonder, "What if it springs a leak?"
By JANET ZINK
Published March 26, 2004
LITHIA - It's something Rob Reutti is used to. Every time it rains, his back yard floods.
The problem will only get worse once the massive Tampa Bay Regional Reservoir is finished, he figures. The construction alone has exacerbated the situation.
"Drainage was already a problem and this reservoir is making it worse," said Reutti, who lives on Wendel Avenue fewer than 1,000 feet from the reservoir.
When full, the reservoir will be able to hold about 15-billion gallons of water, or about 33 times the volume of Raymond James Stadium. That, officials say, will be enough to supply 25 percent of the region's drinking water for more than six months.
But some residents worry about the reservoir's impact on their property and safety.
Experts estimate that the weight of the water will push up the surrounding water table by at least a foot. That's likely to cause not just an inconvenience, but problems with septic tanks and wells, and change the character of nearby wildlife habitats.
And what if all that water somehow breaks free?
Tampa Bay Water has created an emergency action plan for the reservoir in case of a break, which according to Hillsborough County consultants could impact thousands of people with homes and workplaces along the Alafia River. Experts say the likelihood of such a disaster are slim.
But some people living around the reservoir aren't convinced.
"What if it springs a leak? We don't stand a ghost of a chance of getting out of here," said Wilma Shiver, who has owned 40 acres on County Road 39 since 1962. Two of her children also live on the property. "If it bursts out here, they're going to have some kind of a bill if there is anyone here to collect it."
Wendel Avenue resident Charlayne Penrose said before construction of the reservoir began in May 2002, county officials visited nearby residents and told them that if there was a severe break in the earthen wall, everything in the water's path would be swept away, including grass.
"You cannot feel safe," she said.
In early 2001, Hillsborough County and the developers of FishHawk Ranch, a community located less than 3 miles north of the reservoir site, challenged Tampa Bay Water's Environmental Resource permit application because of concerns about safety.
FishHawk abandoned its challenge after selling the county some land near the reservoir, said Don Whyte, regional vice president of Newland Communities, FishHawk Ranch's developer.
The land is now an environmentally protected area.
The county continued its challenge, however.
In May 2001 an independent arbitration panel released a 96-page decision stating that Tampa Bay Water had provided reasonable assurance that the reservoir would be stable.
The decision required Tampa Bay Water to produce a study showing what areas would be affected by a breach and an emergency action plan in case of a failure.
The plan should be in place by May, said the reservoir's project manager, Amanda Rice.
It designates responsibilities in an emergency and outlines an early warning system and reservoir monitoring.
The worst case scenario - a break at the northwest corner of the reservoir that would send water to FishHawk Creek, the Alafia River and Tampa Bay - could impact 1,455 single-family homes, 216 mobile homes, 45 government buildings and 81 institutional properties. Those include Boyette Springs Elementary School, Riverview Elementary School, Lithia Springs Elementary School and several church-owned properties.
Notification methods include sirens audible one mile away, automatic telephone calls and special alert radios placed in homes.
"It's not something we ever expect to have to implement," Rice said.
Tampa Bay Water officials say the reservoir is state of the art. They and experts involved in construction of other reservoirs say the likelihood of problems are slim because of its design and safety features.
Tampa Bay Water began construction in May 2002 on Florida's only off-stream reservoir, which means it's not created by damming an existing body of water. Instead, it's meant to act as a giant rain cistern. The reservoir will be filled by pumping water into it from the Alafia and Hillsborough rivers during rainy seasons. Then during dry times, that water will be sent to the regional treatment plant and distributed to customers. "You're pumping into it so you have control over how much water is going in there," said Keith Banachowski, an Ohio State University civil engineer and dam safety expert.
That alone virtually eliminates the possibility of water overtopping the embankment, he said.
Tampa Bay Water officials say the reservoir will probably be filled to capacity only 15 percent of the time. It will be half-full only half the time.
In addition, Rice said, a 9-foot soil-cement stair-step that surrounds the reservoir from the top water level line to the edge of the embankment will break escaping waves if there's a storm.
The design should allow the reservoir to withstand a storm that brings 40 inches of rain in 24 hours and 110 mph sustained winds.
According to the National Hurricane Center, one of the strongest hurricanes to hit Florida was Andrew in 1992, which packed winds of more than 155 mph. Among the wettest storms was the tropical depression, Dennis, in 1981, which dumped more than 20 inches of rain.
"I don't recall any hurricane that has dumped 40 inches in 24 hours," said hurricane forecaster Lexion Avila.
The Department of the Interior, Rice said, advised that accommodating 57 mph sustained winds would be adequate.
"By choosing 110 mph we have been very conservative," Rice said.
Additional features minimize the amount of water that could leak out of the reservoir and weaken the earthen walls that contain the water.
One is a cut-off wall made of earth mixed with bentonite mined in Wyoming. Bentonite is a particularly strong clay capable of absorbing 7 to 10 times its own weight in water.
The bentonite clay fills a 3-foot-wide, 30- to 70-foot-deep trench dug around the perimeter of the reservoir just inside the embankment. The bentonite wall connects with a layer of clay that occurs naturally under the entire reservoir.
Plus, a layer of high-density plastic lining topped with compacted dirt and soil cement rests on top of the embankment to prevent leakage.
"The main thing is when you build a dam is you're trying to control seepage. You can never prevent it but you try to control it so that the safety of the dam remains intact," said David Carrier, a civil engineer at Argila Enterprises who evaluated the reservoir for the Department of Environmental Protection.
Well-designed and constructed earth dams have a 0.01 percent chance of failing in any given year, Carrier said, which translates into a 1 percent chance over 100 years.
Still, concerns about safety exist. Unlike some other states, Florida has no standards for guaranteeing the safety of dams, although the DEP permit states that the reservoir design is a solid one.
"Whatever criteria is being used is an awfully lax one," said County Commissioner Pat Frank.
She points to the 1997 breach at the Mulberry Phosphates reservoir in Polk County as an example of the damage a defect can cause. That break sent 53-million gallons of acidic water into surface waters of the state with impacts as far downstream as the mouth of the Alafia River. The spill killed a large number of aquatic plants and animals.
"They are now building this wall of dirt that's going to hover over the homes down there," Frank said. "I can't imagine the horror of living in that area."
Carrier countered that dams associated with mining operations fail 10 times more often than water supply dams.
"This dam is safer," Carrier said. "It's built to higher standards."
The makeup of the land the reservoir sits on was studied extensively before the first bit of earth was turned, he said. It took almost four years for Tampa Bay Water to get all the necessary permits for construction.
"There was far more done for this dam than was ever done for a phosphate dam or a phosphogypsum dam," he said.
This type of reservoir, he said, makes sense for Florida, where there aren't valleys near rivers that can be dammed to create a large body of water.
"As the need for additional water supply grows because of population growth, it's likely there will be other off-stream reservoirs constructed for the state," Carrier said. "It's a good thing to do."
Nonetheless, Penrose, who lives 1,000 feet from the reservoir, said she's putting her house on the market this year.
"I don't want to live here," she said. "We were happy out here. It's a quiet place, a nice neighborhood. We moved out here for the quiet to raise our kids and have our horses. But with that thing up there, we haven't felt safe since."
