Cracked reservoir is no danger, official says

LITHIA — When Yvonne Blevins looks out her kitchen window, she sees the tall, grassy berm of the C.W. Bill Young Reservoir. The reservoir has cracks and is only about 200 yards from her home.

Blevins, 65, fears that billions of gallons of water will burst through the cracks and race toward her home. She plans to tell her family, "Ya'll go on without me," because she's on an oxygen tank and can't run.

"What would I do?" she asks, and then she thinks of the others. "I hope you've got yourself right with the Lord because you won't have time."

But Tampa Bay Water officials say Blevins and other nearby Lithia residents shouldn't worry.

The cracks affect only about 5 percent of the soil-cement layer of the reservoir, which protects the deep soil layer underneath from erosion. Under the soil layer, there is an impermeable membrane.

"The wall of the bathtub, if you will," said Tampa Bay Water general manager Jerry Seeber. "There's no risk to the safety of the facility whatsoever."

The cracks, in two parts of the reservoir, first were noticed in December 2006. Temporary fixes were unsuccessful, and the utility has spent more than $1-million trying to remedy the problem, Seeber said.

The utility sued three companies it says are responsible about two weeks ago: HDR Engineering, which designed the reservoir; Barnard Construction Co., which built it; and Construction Dynamics Group, which oversaw construction.

"We don't expect the rate payers to bail out the contractors," Seeber said.

Engineers concluded that filling the reservoir and then draining it — the act of lowering the water level — caused the cracks.

The utility opened the reservoir in June 2005 as a place to store water skimmed from the Tampa Bypass Canal and the Alafia and Hillsborough rivers. It covers about 1,100 acres just west of County Road 39 in Lithia, near Alafia River State Park.

The $146-million reservoir can hold about 15-billion gallons but only has about 3-billion now because near-historic lows in the rivers' flows have forced cutbacks, Seeber said.

He hopes to get temporary patches completed by June, when the summer rains start. But until then, officials are encouraging residents to conserve water, especially when irrigating lawns.

The company will be able to provide water through the dry winter and spring seasons, but it may have to pull more groundwater, which isn't ideal, Seeber said.

Temporary patches didn't work in the past, when Tampa Bay Water used a grout mixture to fill in the cracks.

But this time, the utility plans to use an innovative technique, which will start in January.

Olson Engineering will use ground-penetrating radar to search for gaps under the soil-cement layer. The utility fears that water has seeped through the cracks and caused erosion underneath, which would need to be filled. This method would detect those spots.

The mapping will cost $191,500, Seeber said, and he said it will be cheaper and less invasive than the traditional method of digging into the wall with a backhoe.

After it's mapped, two other companies will fill the gaps and the cracks with a "nonweeping sanded grout," which is a grout that won't give off much water or expand once it's put in the gaps and hardens.

That will cost about $1-million, Seeber said.

He's much more confident with this fix because it will fill the gaps as well as the cracks. If this method is approved after a section is tested, it should be finished by June, he said.

The utility plans to seek a permanent fix, but those plans won't come until the summer. It has no estimate of how much that could cost.

Times researcher John Martin and Times staff writer Craig Pittman contributed to this report. Jessica Vander Velde can be reached at jvandervelde@sptimes.com or (813) 661-2443.

Fast facts

What is ground-penetrating radar?

It's a method of mapping below the surface of a structure using radar pulses. It can measure the thickness of slabs and locate voids under concrete. It doesn't destroy the structure, and it can map through a variety of mediums, including concrete, rock and soil.

Cracked reservoir is no danger, official says 12/25/08 [Last modified: Thursday, December 25, 2008 3:30am]

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